Patent Application
20220248956
Various embodiments described and disclosed herein relate to the field of medicine generally, and more particularly to diagnosing, predicting and treating cardiac rhythm disorders such as atrial fibrillation in a patient's heart.
Persistent atrial fibrillation (AF) is assumed to be caused by structural changes in atrial tissue, which can manifest themselves as multiwavelet re-entry and/or stable rotor mechanisms (see, e.g., De Groot M S et al., “Electropathological Substrate of Longstanding Persistent Atrial Fibrillation in Patients with Structural Heart Disease Epicardial Breakthrough,” Circulation, 2010, 3: 1674-1682). Radio frequency (RF) ablation targeting such host drivers of AF is generally accepted as the best therapeutic approach. RF ablation success rates in treating AF cases are currently limited, however, by a lack of diagnostic tools that are capable of precisely determining the source (or type), and location, of such AF drivers. Better diagnostic tools would help reduce the frequency and extent of cardiac ablation procedures to the minimum amount required to treat AF, and would help balance the benefits of decreased fibrillatory burden against the morbidity of increased lesion load.
One method currently employed to localize AF drivers is the TOPERA® RhythmView® system, which employs a basket catheter having 64 electrodes arranged in an 8×8 pattern from which the system records unipolar electrograms or electrogram signals (EGMs). The RhythmView® algorithm creates a propagation map of the 64 electrodes through a phase analysis of EGM peaks after improving the signal to noise ratio through filtering and subtraction of a simulated compound ECG artifact. The RhythmView® algorithm detects where peak sequences between electrodes show a circular pattern candidate for a re-entry cycle and indicates those locations in a Focal Impulse and Rotor Map (FIRM) using A1 to H8 chess field coordinates for the electrodes. The resolution of the TOPERA system is limited by the spacing of the electrodes and consequently does not show the details of the AF drivers. In particular, the TOPERA system cannot show if a circular EGM wavefront is actively generated by a re-entry mechanism and is therefore is a driver of AF (i.e., an active rotor), or whether a circular EGM wavefront simply represents turbulence passively generated by an EGM wavefront hitting a barrier (i.e., a passive rotor). In addition, the TOPERA system does not show the direction of AF wavefront propagation, and does not provide the spatial or temporal resolution required to detect singularities associated with the generation of an active rotor.
A recent independent multicenter study (“OASIS, Impact of Rotor Ablation in Non-Paroxysmal AF Patients: Results from a Randomized Trial,” Sanghamitra Mohanty, et al. and Andrea Natale, J Am Coll Cardiol. 2016) reported that the results obtained using TOPERA FIRM technology were inferior to those provided by non-specific ablation of the posterior wall of the left atrium. Moreover, the results suggested that FIRM based ablation is not sufficient for therapeutic success without pulmonary vein isolation (PVI) being performed in parallel. Although there are some questions about the methodology of this trial, many experts are convinced that the resolution and interpretability of the TOPERA system need to be improved.
In another approach to the problem, Toronto scientists recently presented a strategy to analyze EGM wave propagation using “Omnipolar Mapping,” which seeks to measure beat-by-beat conduction velocity and direction (see, e.g., “Novel Strategy for Improved Substrate Mapping of the Atria: Omnipolar Catheter and Signal Processing Technology Assesses Electrogram Signals Along Physiologic and Anatomic Directions,” D. Curtis Deno et al. and Kumaraswamy Nanthakumar; Circulation. 2015; 132-A19778). This approach starts with the time derivative of a unipolar EGM as measured by a set of electrodes having known distances to one other. Assuming constant velocity, the velocity and direction representing the best fit for a spatial derivative of the measured EGM are calculated and used to represent an estimate of the E field. According to a communication by Dr. Nanthakumar at the 2016 CardioStim Convention in Nice, France, however, this method remains incapable of dealing successfully with complex data sets, such as those obtained during an episode of AF.
AF is the most common supraventricular tachyarrhythmia worldwide and is associated with a significant health burden. Catheter ablation of pulmonary veins (PV) has been established as a therapeutic option for patients with symptomatic drug-refractory paroxysmal AF and results in high clinical success. However, the treatment of persistent and long-standing persistent AF is still challenging. A large number of patients present with recurrence of atrial tachyarrhythmia during mid- and long-term follow up. To achieve higher success rates, different ablation strategies have been reported, such as targeting additional AF sources. The initial results of focal impulse and rotor (FIRM) mapping for guiding catheter ablation of AF seemed to be promising. However, currently available systems for AF driver identification still have significant limitations, such as limited spatial resolution and difficulties in discriminating between active and passive rotors.
What is needed are improved means and methods of acquiring and processing intracardiac electrogram signals that reliably and accurately yield the precise locations and sources of cardiac rhythm disorders in a patient's heart. Doing so would enable cardiac ablation procedures to be carried out with greater locational precision, and would result in higher rates of success in treating cardiac rhythm disorders such as AF.
In one embodiment, there is provided a system configured to classify, and to detect at least one location or type of at least one source of, at least one cardiac rhythm disorder in a patient's heart, the system comprising one or more body surface electrodes, the one or more electrodes being configured to be positioned in physical contact with the patient's body surface and to be operably connected to electrical and electronic circuitry configured to provide as outputs therefrom body surface electrogram data representative of cardiac signals acquired from the patient, the circuitry being operably connected wirelessly or though electrical conductors to provide the cardiac signals to a computing device, wherein the computing device comprises at least one non-transitory computer readable medium configured to store instructions executable by at least one processor to determine the at least one location and functional type of the at least one source of the at least one cardiac rhythm disorder in the patient's heart and then to classify same, the computing device being configured to: (i) receive the cardiac signal data; (ii) using at least one of an electrographic flow (EGF) method, video tracking analysis, motion capture analysis, motion estimation analysis, data association and segmentation tracking analysis, particle tracking analysis, and single-particle tracking analysis methods to determine the at least one location and type of the at least one source of the at least one cardiac rhythm disorder in the patient's heart; and (iii) use electrographic volatility index (EVI) methods to classify the at least one cardiac rhythm disorder.
The system may further comprise one or more of: (i) the one or more body surface electrodes being mounted on or attached to a body wearable patch, ECG lead, vest or clothing item configured to be worn by or attached to the patient; (ii) the at least one processor and the at least one non-transitory computer readable medium being configured to determine, using a trained atrial discriminative machine learning model, predictions or results concerning atrial fibrillation in the patient's heart; (iii) the trained atrial discriminative machine learning model having been trained at least partially using data obtained from a plurality of other previous patients, where body surface electrode cardiac signals for the other patients were processed using EVI methods and one or more of EGF, video tracking analysis, motion capture analysis, motion estimation analysis, data association and segmentation tracking analysis, particle tracking analysis, and single-particle tracking analysis methods; (iv) the computing device being configured to generate one or more of activity levels of sources of atrial fibrillation in the patient's heart, spatial variability levels of sources of atrial fibrillation in the patient's heart, flow angle stability levels of sources of atrial fibrillation in the patient's heart, and classification of patient's AF state as at least one of types A, B, C, D and E; (v) paired data sets of body surface electrogram cardiac signals and intracardiac EP mapping signals being acquired simultaneously from at least some of the plurality of other patients and the paired data sets being correlated to one another using the trained atrial discriminative machine model; (vi) a trained atrial discriminative machine learning model being further configured to generate one or more of the following predictions or results for the patient using the conditioned electrogram signals and positional data corresponding to the patient: (1) Does the patient have atrial fibrillation or not? (2) If the patient has atrial fibrillation, determining at least one of the spatial variability level, the activity level, and the flow angle stability level associated with one or more sources detected in the patient's heart; (3) If the patient has atrial fibrillation, determining the locations of one or more sources detected in the patient's heart; (4) If the patient has atrial fibrillation, whether one or more activation sources detected in the patient's heart are characterized by chaotic flow; and (5) classification of the patient as one or more of types A, B, C, D or E; (vii) the computing device being configured to: (1) process cardiac signal data and electrode position data in the trained machine learning model to generate the one or more predictions or results; and (2) display the one or more predictions or results on a display or monitor to a user; (viii) the EGF method being selected from the group consisting of a Horn-Schunck method, a Buxton-Buston method, a Black-Jepson method, a phase correlation method, a block-based method, a discrete optimization method, a Lucas-Kanade method, and a differential method of estimating optical flow; (ix) the body surface electrodes being incorporated into individual or interconnected cardiac monitoring patches, a wearable vest, a wearable band or strap, or a wearable item or clothing item; (x) incorporating the body surface electrodes into one or more of a 1-lead ECG monitoring lead, a 3-lead ECG monitoring lead, a 5-lead ECG monitoring lead, and a 12-lead ECG monitoring lead; (xi) incorporating the body surface electrodes into at least one patch, wearable item, or ECG lead comprising circuitry configured to telemeter or send data therefrom via BLUETOOTH or WiFi to the computing device; and (xii) the circuitry is configured to receive instructions, data, and programs from the computing device.
In another embodiment, there is provided a method for classifying and detecting at least one location or type of at least one source of, at least one cardiac rhythm disorder in a patient's heart, using a system, the system comprising one or more body surface electrodes, the one or more electrodes being configured to be positioned in physical contact with the patient's body surface and to be operably connected to electrical and electronic circuitry configured to provide as outputs therefrom body surface electrogram data representative of cardiac signals acquired from the patient, the circuitry being operably connected wirelessly or though electrical conductors to provide the cardiac signals to a computing device, wherein the computing device comprises at least one non-transitory computer readable medium configured to store instructions executable by at least one processor to determine the at least one location and type of the at least one source of the at least one cardiac rhythm disorder in the patient's heart and then to classify same, the computing device being configured to: (i) receive the cardiac signal data; (ii) using at least one of an electrographic flow (EGF) method, video tracking analysis, motion capture analysis, motion estimation analysis, data association and segmentation tracking analysis, particle tracking analysis, and single-particle tracking analysis methods to determine the at least one location and type of the at least one source of the at least one cardiac rhythm disorder in the patient's heart; and (iii) use electrographic volatility index (EVI) methods to classify the at least one cardiac rhythm disorder, the method comprising: (i) receiving the cardiac signal data; (ii) using at least one of the electrographic flow (EGF) method, video tracking analysis, motion capture analysis, motion estimation analysis, data association and segmentation tracking analysis, particle tracking analysis, and single-particle tracking analysis, determining the at least one location and type of the at least one source of the at least one cardiac rhythm disorder in the patient's heart; and (iii) using the electrographic volatility index (EVI) methods, classifying the at least one cardiac rhythm disorder.
The method may further comprise one or more of: (i) mounting or attaching the one or more body surface electrodes to a body wearable patch, ECG lead, vest or clothing item configured to be worn by or attached to the patient; (ii) generating in the computing device one or more of activity levels of sources of atrial fibrillation in the patient's heart, spatial variability levels of sources of atrial fibrillation in the patient's heart, flow angle stability levels of sources of atrial fibrillation in the patient's heart, and classification of patient's AF state as at least one of types A, B, C, D and E; (iii) the computing device being configured to determine, using a trained atrial discriminative machine learning model, predictions or results concerning atrial fibrillation in the patient's heart; (iv) training the atrial discriminative machine learning model at least partially using data obtained from a plurality of other previous patients, where body surface electrode cardiac signals for the other patients have been processed using EVI methods and one or more of EGF, video tracking analysis, motion capture analysis, motion estimation analysis, data association and segmentation tracking analysis, particle tracking analysis, and single-particle tracking analysis methods; (v) acquiring paired data sets of body surface electrogram data and intracardiac EP mapping signals simultaneously from at least some of the plurality of other patients and correlating the paired data sets to one another using the trained atrial discriminative machine model; (vi) the trained atrial discriminative machine learning model generating one or more of the following predictions or results for the patient using the body surface electrogram data: (1) Does the patient have atrial fibrillation or not? (2) If the patient has atrial fibrillation, determining at least one of the spatial variability level, the activity level, and the flow angle stability level associated with one or more sources detected in the patient's heart; (3) If the patient has atrial fibrillation, determining the locations of one or more sources detected in the patient's heart; (4) If the patient has atrial fibrillation, whether one or more activation sources detected in the patient's heart are characterized by chaotic flow; and (5) classification of the patient as one or more of types A, B, C, D or E; (vii) processing the body surface electrogram data in the trained machine learning model to generate the one or more predictions or results; and displaying the one or more predictions or results on a display or monitor to a user; (viii) selecting the EGF method from the group consisting of a Horn-Schunck method, a Buxton-Buston method, a Black-Jepson method, a phase correlation method, a block-based method, a discrete optimization method, a Lucas-Kanade method, and a differential method of estimating optical flow; (ix) incorporating the body surface electrodes into individual or interconnected cardiac monitoring patches, a wearable vest, a wearable band or strap, or a wearable item or clothing item; (x) incorporating the body surface electrodes into one or more of a 1-lead ECG monitoring lead, a 3-lead ECG monitoring lead, a 5-lead ECG monitoring lead, and a 12-lead ECG monitoring lead; (xi) incorporating the body surface electrodes into at least one patch, wearable item, or ECG lead comprising circuitry configured to telemeter or send data therefrom via BLUETOOTH or WiFi to the computing device; and (xii) the circuitry being configured to receive instructions, data, and programs from the computing device.
Further embodiments are disclosed herein or will become apparent to those skilled in the art after having read and understood the claims, specification and drawings hereof.
The patent or application file contains at least one drawing executed in color. Copies of this patent or patent application publication with color drawing(s) will be provided by the Office upon request and payment of the necessary fee.
Different aspects of the various embodiments will become apparent from the following specification, drawings and claims in which:
The drawings are not necessarily to scale. Like numbers refer to like parts or steps throughout the drawings.
Described herein are various embodiments of systems, devices, components and methods for diagnosing and treating cardiac rhythm disorders in a patient's heart using electrophysiological mapping or electrographic flow (EGF) techniques, as well as imaging, navigation, cardiac ablation and other types of medical systems, devices, components, and methods. Various embodiments described and disclosed herein also relate to systems, devices, components and methods for discovering with enhanced precision the location(s) of the source(s) of different types of cardiac rhythm disorders and irregularities. Such cardiac rhythm disorders and irregularities, include, but are not limited to, arrhythmias, atrial fibrillation (AF or A-fib), atrial tachycardia, atrial flutter, paroxysmal fibrillation, paroxysmal flutter, persistent fibrillation, ventricular fibrillation (V-fib), ventricular tachycardia, atrial tachycardia (A-tach), ventricular tachycardia (V-tach), supraventricular tachycardia (SVT), paroxysmal supraventricular tachycardia (PSVT), Wolff-Parkinson-White syndrome, bradycardia, sinus bradycardia, ectopic atrial bradycardia, junctional bradycardia, heart blocks, atrioventricular block, idioventricular rhythm, areas of fibrosis, breakthrough points, focus points, re-entry points, premature atrial contractions (PACs), premature ventricular contractions (PVCs), and other types of cardiac rhythm disorders and irregularities.
Various embodiments of EGF techniques, methods, systems, devices, and components are described and disclosed herein, which involve the acquisition of intra-cardiac and/or body surface electrograms, and the subsequent processing and analysis of such electrograms to reveal the locations of sources of cardiac rhythm disorders in a patient's heart, such as rotors and sources that cause or contribute to AF. That is, many of the various techniques, methods, systems, devices, and components described and disclosed herein may be referred to collectively as pertaining to “EGF.”
Systems and methods configured to detect in a patient's heart a location of a source of at least one cardiac rhythm disorder are disclosed herein. In the following description, for the purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of example embodiments or aspects. It will be evident, however, to one skilled in the art that an example embodiment may be practiced without necessarily using all of the disclosed specific details.
Referring now to
The embodiment of system 100 shown in
Instead of being operably connected (e.g., through Bluetooth signals, a LAN or WAN network, or through the cloud), or directly connected, to computing device 300, data acquisition device 140 may be configured to provide as outputs therefrom saved or stored body surface electrogram signals, which can be, by way of example, saved or stored on a hard drive, in a memory, on a USB stick, or other suitable storage device, and where the saved or stored body surface electrogram signals are later or subsequently provided as inputs to computing device 300 for processing and analysis.
Computer or computing device 300 may be configured to receive operator inputs from an input device 320 such as a keyboard, mouse and/or control panel. Outputs from computer 300 may be displayed on display or monitor 324 or other output devices (not shown in
During electrophysiological (EP) mapping procedures, multi-electrode catheter 110 is typically introduced percutaneously into the patient's heart 10. Catheter 110 is passed through a blood vessel (not shown), such as a femoral vein or the aorta, and thence into an endocardial site such as the atrium or ventricle of the heart 10.
It is contemplated that other catheters, including other types of mapping or EP catheters, lasso catheters, pulmonary vein isolation (PVI) ablation catheters (which can operate in conjunction with sensing lasso catheters), ablation catheters, navigation catheters, and other types of EP mapping catheters such as EP monitoring catheters and spiral catheters may also be introduced into the heart, and that additional surface electrodes may be attached to the skin of the patient to record electrocardiograms (ECGs).
When system 100 is operating in an EP mapping mode, multi-electrode catheter 110 functions as a detector of intra-electrocardiac signals, while optional surface electrodes may serve as detectors of surface ECGs. In one embodiment, the analog signals obtained from the intracardiac and/or surface electrodes are routed by multiplexer 146 to data acquisition device 140, which comprises an amplifier 142 and an A/D converter (ADC) 144. The amplified or conditioned electrogram signals may be displayed by electrocardiogram (ECG) monitor 148. The analog signals are also digitized via ADC 144 and input into computer 300 for data processing, analysis and graphical display.
In one embodiment, catheter 110 is configured to detect cardiac activation information in the patient's heart 10, and to transmit the detected cardiac activation information to data acquisition device 140, either via a wireless or wired connection. In one embodiment that is not intended to be limiting with respect to the number, arrangement, configuration, or types of electrodes, catheter 110 includes a plurality of 64 electrodes, probes and/or sensors A1 through H8 arranged in an 8×8 grid that are included in electrode mapping assembly 120, which is configured for insertion into the patient's heart through the patient's blood vessels and/or veins. Other numbers, arrangements, configurations and types of electrodes in catheter 110 are, however, also contemplated. In most of the various embodiments, at least some electrodes, probes and/or sensors included in catheter 110 are configured to detect cardiac activation or electrical signals, and to generate electrocardiograms or electrogram signals, which are then relayed by electrical conductors from or near the distal end 112 of catheter 110 to proximal end 116 of catheter 110 to data acquisition device 140.
Note that in some embodiments of system 100, multiplexer 146 is not employed for various reasons, such as sufficient electrical conductors being provided in catheter 110 for all electrode channels, or other hardware design considerations. In other embodiments, multiplexer 146 is incorporated into catheter 110 or into data acquisition device 140. In still further embodiments, multiplexer 146 is optional or not provided at all, and data acquisition device 140, ablation module 150, and/or pacing module 160 are employed separately and/or operate independently from one another. In addition, in some embodiments computing device 300 may be combined or integrated with one or more of data acquisition device 140, ablation module 150, and/or pacing module 160.
In one embodiment, a medical practitioner or health care professional employs catheter 110 as a roving catheter to locate the site of the location of the source of a cardiac rhythm disorder or irregularity in the endocardium quickly and accurately, without the need for open-chest and open-heart surgery. In one embodiment, this is accomplished by using multi-electrode catheter 110 in combination with real-time or near-real-time data processing and interactive display by computer 300, and optionally in combination with imaging and/or navigation system 70. In one embodiment, multi-electrode catheter 110 deploys at least a two-dimensional array of electrodes against a site of the endocardium at a location that is to be mapped, such as through the use of a Biosense Webster® PENTARAY® EP mapping catheter. The intracardiac or electrogram signals detected by the catheter's electrodes provide data sampling of the electrical activity in the local site spanned by the array of electrodes.
In one embodiment, the electrogram signal data are processed by computer 300 to produce a display showing the locations(s) of the source(s) of cardiac rhythm disorders and/or irregularities in the patient's heart 10 in real-time or near-real-time, further details of which are provided below. That is, at and between the sampled locations of the patient's endocardium, computer 300 may be configured to compute and display in real-time or near-real-time an estimated, detected and/or determined location(s) of the site(s), source(s) or origin)s) of the cardiac rhythm disorder(s) and/or irregularity(s) within the patient's heart 10. This permits a medical practitioner to move interactively and quickly the electrodes of catheter 110 towards the location of the source of the cardiac rhythm disorder or irregularity.
In some embodiments of system 100, one or more electrodes, sensors or probes detect cardiac activation from the surface of the patient's body as surface ECGs, or remotely without contacting the patient's body (e.g., using magnetocardiograms). In another example, some electrodes, sensors or probes may derive cardiac activation information from echocardiograms. In various embodiments of system 100, external or surface electrodes, sensors and/or probes can be used separately or in different combinations, and further may also be used in combination with intracardiac electrodes, sensors and/or probes inserted within the patient's heart 10. Many different permutations and combinations of the various components of system 100 are contemplated having, for example, reduced, additional or different numbers of electrical sensing and other types of electrodes, sensors and/or transducers.
Continuing to refer to
As discussed above, in some embodiments, multiplexer 146 is separate from catheter 110 and data acquisition device 140, and in other embodiments multiplexer 146 is combined in catheter 110 or data acquisition device 140.
In some embodiments, the rate at which individual electrogram and/or ECG signals are sampled and acquired by system 100 can range between about 0.25 milliseconds and about 8 milliseconds, and may be about 0.5 milliseconds, about 1 millisecond, about 2 milliseconds or about 4 milliseconds. Other sample rates are also contemplated. While in some embodiments system 100 is configured to provide unipolar signals, in other embodiments system 100 is configured to provide bipolar signals.
In one embodiment, system 100 can include a BARD® LABSYSTEM™ PRO EP Recording System, which is a computer and software driven data acquisition and analysis tool designed to facilitate the gathering, display, analysis, pacing, mapping, and storage of intracardiac EP data. Also in one embodiment, data acquisition device 140 can include a BARD® CLEARSIGN™ amplifier, which is configured to amplify and condition electrocardiographic signals of biologic origin and pressure transducer input, and transmit such information to a host computer (e.g., computer 300 or another computer).
As shown in
When system 100 is operating in an optional ablation mode, multi-electrode catheter 110 fitted with ablation electrodes, or a separate ablation catheter, is energized by ablation module 150 under the control of computer 300, control interface 170, and/or another control device or module. For example, an operator may issue a command to ablation module 150 through input device 320 to computer 300. In one embodiment, computer 300 or another device controls ablation module 150 through control interface 170. Control of ablation module 150 can initiate the delivery of a programmed series of electrical energy pulses to the endocardium via catheter 110 (or a separate ablation catheter, not shown in
In an alternative embodiment, ablation module 150 is not controlled by computer 300, and is operated manually directly under operator control. Similarly, pacing module 160 may also be operated manually directly under operator control. The connections of the various components of system 100 to catheter 110, to auxiliary catheters, or to surface electrodes may also be switched manually or using multiplexer 146 or another device or module.
When system 100 is operating in an optional pacing mode, multi-electrode catheter 110 is energized by pacing module 160 operating under the control of computer 300 or another control device or module. For example, an operator may issue a command through input device 320 such that computer 300 controls pacing module 160 through control interface 170, and multiplexer 146 initiates the delivery of a programmed series of electrical simulating pulses to the endocardium via the catheter 110 or another auxiliary catheter (not shown in
Computing device or computer 300 is appropriately configured and programmed to receive or access the electrogram signals provided by data acquisition device 140. Computer 300 is further configured to analyze or process such electrogram signals in accordance with the methods, functions and logic disclosed and described herein so as to permit reconstruction of cardiac activation information from the electrogram signals. This, in turn, makes it possible to locate with at least some reasonable degree of precision the location of the source of a heart rhythm disorder or irregularity. Once such a location has been discovered, the source may be eliminated or treated by means that include, but are not limited to, cardiac ablation.
In one embodiment, and as shown in
In one embodiment, system 100 further comprises or operates in conjunction with catheter or electrode position transmitting and/or receiving coils or antennas located at or near the distal end of an EP mapping catheter 110, or that of an ablation or navigation catheter 110, which are configured to transmit electromagnetic signals for intra-body navigational and positional purposes.
In one embodiment, imaging or navigation system 70 is used to help identify and determine the precise two- or three-dimensional positions of the various electrodes included in catheter 110 within patient's heart 10, and is configured to provide electrode position data to computer 300. Electrodes, position markers, and/or radio-opaque markers can be located on various portions of catheter 110, mapping electrode assembly 120 and/or distal end 112, or can be configured to act as fiducial markers for imaging or navigation system 70.
Medical navigation systems suitable for use in the various embodiments described and disclosed herein include, but are not limited to, image-based navigation systems, model-based navigation systems, optical navigation systems, electromagnetic navigation systems (e.g., BIOSENSE® WEBSTER® CARTO® system), and impedance-based navigation systems (e.g., the St. Jude® ENSITE™ VELOCITY™ cardiac mapping system), and systems that combine attributes from different types of imaging AND navigation systems and devices to provide navigation within the human body (e.g., the MEDTRONIC® STEALTHSTATION® system).
In view of the structural and functional descriptions provided herein, those skilled in the art will appreciate that portions of the described devices and methods may be configured as processes, methods, data processing systems, and/or computer methods. Accordingly, these portions of the devices and methods described herein may take the form of a hardware embodiment, a software embodiment, or an embodiment combining software and hardware, such as shown and described with respect to computer system 300 illustrated in
Certain embodiments of portions of the devices and methods described herein are also described with reference to block diagrams of methods, processes, and systems. It will be understood that such block diagrams, and combinations of blocks diagrams in the Figures, can be implemented using computer-executable instructions. These computer-executable instructions may be provided to one or more processors of a general purpose computer, a special purpose computer, or any other suitable programmable data processing apparatus (or a combination of devices and circuits) to produce a machine, such that the instructions, which executed via the processor(s), implement the functions specified in the block or blocks of the block diagrams.
These computer-executable instructions may also be stored in a computer-readable memory that can direct computer 300 or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory result in an article of manufacture including instructions which implement the function specified in an individual block, plurality of blocks, or block diagram. The computer program instructions may also be loaded onto computer 300 or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on computer 300 or other programmable apparatus provide steps for implementing the functions specified in the an individual block, plurality of blocks, or block diagram.
In this regard,
Computer system 300 can be implemented on one or more general purpose computer systems or networked computer systems, embedded computer systems, routers, switches, server devices, client devices, various intermediate devices/nodes or standalone computer systems. Additionally, computer system 300 or portions thereof may be implemented on various mobile devices such as, for example, a personal digital assistant (PDA), a laptop computer and the like, provided the mobile device includes sufficient processing capabilities to perform the required functionality.
In one embodiment, computer system 300 includes processing unit 301 (which may comprise a CPU, controller, microcontroller, processor, microprocessor or any other suitable processing device), system memory 302, and system bus 303 that operably connects various system components, including the system memory, to processing unit 301. Multiple processors and other multi-processor architectures also can be used to form processing unit 301. System bus 303 can comprise any of several types of suitable bus architectures, including a memory bus or memory controller, a peripheral bus, or a local bus. System memory 302 can include read only memory (ROM) 304 and random access memory (RAM) 305. A basic input/output system (BIOS) 306 can be stored in ROM 304 and contain basic routines configured to transfer information and/or data among the various elements within computer system 300.
Computer system 300 can include a hard disk drive 303, a magnetic disk drive 308 (e.g., to read from or write to removable disk 309), or an optical disk drive 310 (e.g., for reading CD-ROM disk 311 or to read from or write to other optical media). Hard disk drive 303, magnetic disk drive 308, and optical disk drive 310 are connected to system bus 303 by a hard disk drive interface 312, a magnetic disk drive interface 313, and an optical drive interface 314, respectively. The drives and their associated computer-readable media are configured to provide nonvolatile storage of data, data structures, and computer-executable instructions for computer system 300. Although the description of computer-readable media above refers to a hard disk, a removable magnetic disk and a CD, other types of media that are readable by a computer, such as magnetic cassettes, flash memory cards, digital video disks and the like, in a variety of forms, may also be used in the operating environment; further, any such media may contain computer-executable instructions for implementing one or more parts of the devices and methods described and disclosed herein.
A number of program modules may be stored in drives and RAM 303, including operating system 315, one or more application programs 316, other program modules 313, and program data 318. The application programs and program data can include functions and methods programmed to acquire, process and display electrical data from one or more sensors, such as shown and described herein. The application programs and program data can include functions and methods programmed and configured to process data acquired from a patient for assessing heart function and/or for determining parameters for delivering a therapy and/or assessing heart function, such as shown and described herein with respect to
A health care provider or other user may enter commands and information into computer system 300 through one or more input devices 320, such as a pointing device (e.g., a mouse, a touch screen, etc.), a keyboard, a microphone, a joystick, a game pad, a scanner, and the like. For example, the user can employ input device 320 to edit or modify the data being input into a data processing method (e.g., only data corresponding to certain time intervals). These and other input devices 320 may be connected to processing unit 301 through a corresponding input device interface or port 322 that is operably coupled to the system bus, but may be connected by other interfaces or ports, such as a parallel port, a serial port, or a universal serial bus (USB). One or more output devices 324 (e.g., display, a monitor, a printer, a projector, or other type of display device) may also be operably connected to system bus 303 via interface 326, such as through a video adapter.
Computer system 300 may operate in a networked environment employing logical connections to one or more remote computers, such as remote computer 328. Remote computer 328 may be a workstation, a computer system, a router, or a network node, and may include connections to many or all the elements described relative to computer system 300. The logical connections, schematically indicated at 330, can include a local area network (LAN) and/or a wide area network (WAN).
When used in a LAN networking environment, computer system 300 can be connected to a local network through a network interface or adapter 332. When used in a WAN networking environment, computer system 300 may include a modem, or may be connected to a communications server on the LAN. The modem, which may be internal or external, can be connected to system bus 303 via an appropriate port interface. In a networked environment, application programs 316 or program data 318 depicted relative to computer system 300, or portions thereof, may be stored in a remote memory storage device 340.
Referring now to
Method 200 outlined in
As described above, in step 210 of
In one embodiment, electrogram signal data acquired from the patient's heart 10 are not equidistantly sampled. For example, in one such embodiment, electrogram signal data acquired from the patient's heart 10 are not equidistantly sampled by mapping electrode assembly 120, and instead are assigned their respective chessboard locations A1 through H8 as approximations of electrode locations in a cylindrical 2D projection of a grid representative of the interior surface of the patient's heart that is being mapped. In many applications, it has been discovered that such approximations of electrode locations yield perfectly useable and accurate results when steps 230 through 250 are carried out after steps 210 and 230.
In another embodiment, when superimposing the acquired electrogram signal data onto a 2D or 3D map or grid in step 230, the electrogram signal data may be associated with their actual or more accurately estimated positions in the 2D projection of the grid using positional data provided by, for example, imaging or navigation system 70. Resampling of electrogram signals on the grid may also be carried out. Gridding may also be carried out such as by convolution-type filtering, Kriging, and using splines. Most gridding techniques operate on an equidistant grid and solve the equations governing the gridding process with either finite difference or finite element implementations.
One approach that has been discovered to work particularly well with electrogram signal data is to determine the Green's function associated with each electrogram value assigned to a given chessboard location, and then construct the solution as a sum of contributions from each data point, weighted by the Green's function evaluated for each point of separation. Biharmonic spline interpolation, which as described above may be employed in conjunction with Green's function, has also been discovered to work especially well in the context of processing and analyzing electrogram signal data. In some embodiments, undesirable oscillations between data points are removed by interpolation with splines in tension, also using Green's function. A Green's function technique for interpolation and surface fitting and generation of electrogram signal data has been found to be superior to conventional finite-difference methods because, among other things, the model can be evaluated at arbitrary x,y locations rather than only on a rectangular grid. This is a very important advantage of using Green's function in step 240, because precise evenly-spaced-apart grid locations, resampling of electrogram signals, and finite-difference gridding calculations are not required to generate accurate representations of electrogram surfaces in step 240.
In one embodiment, Green's function G(x; x′) is employed in step 240 for a chosen spline and geometry to interpolate data at regular or arbitrary output locations. Mathematically, the solution is w(x)=sum {c(i) G(x′; x(i))}, for i=1, n, and a number of data points {x(i), w(i)}. Once the n coefficients c(i) have been calculated, the sum may be evaluated at any output point x. A selection is made between minimum curvature, regularized, or continuous curvature splines in tension for either 1-D, 2-D, or 3-D Cartesian coordinates or spherical surface coordinates. After removing a linear or planar trend (i.e., in Cartesian geometries) or mean values (i.e., spherical surfaces) and normalizing residuals, a least-squares matrix solution for spline coefficients c(i) may be determined by solving the n by n linear system w(j)=sum-over-i {(c(i) G(x(j); x(i))}, for j=1, n; this solution yields an exact interpolation of the supplied data points. For further details regarding the methods and mathematics underlying Green's function, see, for example: (1) “Moving Surface Spline Interpolation Based on Green's Function,” Xingsheng Deng and Zhong-an Tang, Math. Geosci (2011), 43:663-680 (“the Deng paper”), and (2) “Interpolation with Splines in Tension: A Green's Function Approach,” Paul Wessel and David Bercovici, Mathematical Geology, 77-93, Vol. 30, No. 1, 1998 (“the Wessel paper”). The respective entireties of the Deng and Wessel papers are hereby incorporated by reference herein.
Still further details regarding the use of Green's function in interpolating and generating surfaces may be found in: Interpolation by regularized spline with tension: 1. Theory and implementation, Mitasova, H., and L. Mitas, 1993, Math. Geol., 25, 641-655; Parker, R. L., 1994, Geophysical Inverse Theory, 386 pp., Princeton Univ. Press, Princeton, N.J.; Sandwell, D. T., 1987, Biharmonic spline interpolation of Geos-3 and Seasat altimeter data, Geophys. Res. Lett., 14, 139-142; Wessel, P., and J. M. Becker, 2008, Interpolation using a generalized Green's function for a spherical surface spline in tension, Geophys. J. Int, 174, 21-28, and Wessel, P., 2009, A general-purpose Green's function interpolator, Computers & Geosciences, 35, 1247-1254. Moving Surface Spline Interpolation Based on Green's Function, Xingsheng Deng, Zhong-an Tang, Mathematical Geosciences, August 2011, Volume 43, Issue 6, pp 663-680.
Note, however, that a number of different surface smoothing, surface fitting, surface estimation and/or surface/data interpolation processing techniques may be employed in step 240 of
As described above, in step 250 of
Two papers describe the Horn-Schunck method particularly well: (1) “SimpleFlow: A Non-Iterative, Sublinear Optical Flow Algorithm,” Michael Tao et al., Eurographics 2012, Vol. 31 (2012), No. 2 (“the Tao paper”), and (2) “Horn-Schunck Optical Flow with a Multi-Scale Strategy,” Enric Meinhardt-Llopis et al., Image Processing On Line, 3 (2013), pp. 151-172 (“the Meinhardt-Llopis paper”). The respective entireties of the Tao and Meinhardt-Llopis papers are hereby incorporated by reference herein.
In “Determining Optical Flow,” by B. K. P. Horn and B. G. Schunck, Artificial Intelligence, Vol. 17, pp. 185-204, 1981, the entirety of which is also hereby incorporated by reference herein, a method for finding an optical flow pattern is described which assumes that the apparent velocity of a brightness pattern varies smoothly throughout most of an image. The Horn-Schunck method assumes smoothness in flow over most or all of an image. Thus, the Horn-Schunck method attempts to minimize distortions in flow and prefers solutions which exhibit smoothness. The Horn-Schunck method of estimating optical flow is a global method which introduces a global constraint of smoothness to solve the aperture problem of optical flow.
A description of some aspects of conventional application of the Horn-Schunck method is set forth in U.S. Pat. No. 6,480,615 to Sun et al. entitled “Motion estimation within a sequence of data frames using optical flow with adaptive gradients,” the entirety of which is also hereby incorporated by reference herein. As described by Sun et al., the Horn-Schunck computation is based on the observation that flow velocity has two components, and that a rate of change of image brightness requires only one constraint. Smoothness of flow is introduced as a second constraint to solve for optical flow. The smoothness constraint presumes there are no spatial discontinuities. As a result, Horn and Schunck excluded situations where objects in an image occlude or block one another. This is because at object boundaries of an occlusion in an image, discontinuities in reflectance appear.
In conventional optical flow analysis, image brightness is considered at pixel (x,y) in an image plane at time t to be represented as a function l(x,y,t). Based on initial assumptions that the intensity structures of local time-varying image regions are approximately constant under motion for at least a short duration, the brightness of a particular point in the image is constant, so that dl/dt=0. Based on the chain rule of differentiation, an optical flow constraint equation (I) can be represented as follows:
lx(x,y,t)·u+l y(x,y,t)·v+l t(x,y,t)=0,
where
lx=∂l(x,y,t∂ax=horizontal spatial gradient of the image intensity;
ly=∂l(x,y,t)/∂y=vertical spatial gradient of the image intensity;
lt=∂l(x,y,t)/∂t=temporal image gradient of the image intensity;
u=dx/dt=horizontal image velocity (or displacement); and
v=dy/dt=vertical image velocity (or displacement).
The above optical flow equation is a linear equation having two unknowns, (i.e., u and v). The component of motion in the direction of the brightness gradient is known to be lt/(lx 2+ly 2)½. However, one cannot determine the component of movement in the direction of the iso-brightness contours at right angles to the brightness gradient. As a consequence, the optical flow velocity (u,v) cannot be computed locally without introducing additional constraints. Horn and Schunck therefore introduce a smoothness constraint. They argue that if every point of the brightness pattern can move independently, then there is little hope of recovering the velocities. However, if opaque objects of finite size are undergoing rigid motion or deformation, neighboring points on the objects should have similar velocities. Correspondingly, the velocity field of the brightness patterns in the image will vary smoothly almost everywhere.
Advantages of the Horn-Schunck method include that it yields a high density of flow vectors, i.e., the flow information missing in inner parts of homogeneous objects is filled in from the motion boundaries. On the negative side, the Horn-Schunck method can be sensitive to noise.
The foregoing discussion regarding how the Horn-Schunck optical flow technique typically focuses on conventional applications, where the brightness or intensity of an object changes over time (which is where the term “optical flow” is derived from). Here, the brightness or intensity of an object is not the issue at hand. Instead, the amplitudes of electrogram signals, and how they change shape and propagate in time and space over a patient's heart, are sought to be determined. One underlying objective of method 200 is to produce a vector velocity map, which is a representation of electrographical flow (and not optical flow) within a patient's heart. Instead of looking for differences or changes in optical brightness or intensity, changes in the velocity, direction and shape of electrical signals (i.e., changes in electrographical flow) across a patient's heart are determined. That is, method 200 does not process optical measurement data corresponding to intensity or brightness, but processes electrical measurement data corresponding to amplitude, potential shape, and/or voltage.
One reason why method 200 works so well in detecting the locations of the sources of cardiac rhythm disorders and irregularities is that ion channels in a patient's heart produce action potential voltages that are relatively constant (except in areas of fibrosis). As described above, the Horn-Schunck method assumes “brightness constancy” as one of its key constraints. The normalized/amplitude-adjusted electrogram signals provided by step 210 help satisfy this key constraint of the Horn-Schunck method so that this method may be applied successfully in step 250.
In addition, because of the stability imparted to electrographical flow solutions determined using the Horn-Schunck method, artifacts and noise are generally low in velocity vector maps generated in step 250. In fact, it is believed that the Horn-Schunck method may generally be applied with greater success to electrographical flow data than to optical data because of the unique nature of action potential signals in the human heart, and the manner in which electrogram signals are processed and conditioned before an optical flow analysis is performed on them as described and disclosed herein.
Method 200 described and disclosed herein also does not employ spatial derivatives of electrical potentials (as is done by Deno et al. and Kumaraswamy Nanthakumar using “omnipolar” signals) or time derivatives of electrogram signals (as is done in the TOPERA system). Time derivatives of signals are known to increase noise. Method 200 has as its key inputs the potentials of electrogram signals (not their derivatives). As a result, method 200 is notably free from the effects of spurious noise and artifacts introduced by time-derivative data processing techniques, including in step 250.
In another embodiment, the velocity vector map of step 250 is generated using the Lucas-Kanade optical flow method, which is a differential method for optical flow estimation developed by Bruce D. Lucas and Takeo Kanade. It assumes that the flow is essentially constant in a local neighbourhood of a pixel under consideration, and solves the basic optical flow equations for all the pixels in that neighborhood using least squares criteria. By combining information from several nearby pixels, the Lucas-Kanade method can often resolve the inherent ambiguity of the optical flow equation. It is also less sensitive to image noise than point-wise methods. On the other hand, since it is a purely local method, it cannot provide flow information in the interior of uniform regions of the image. See “An Iterative Image Registration Technique with an Application to Stereo Vision,” Bruce D. Lucase, Takeo Kanade, Proceedings of Imaging Understanding Workshop, pp. 121-130 (1981), the entirety of which is hereby incorporated by reference herein.
In yet another embodiment, various aspects of the Horn-Schunck and Lucas-Kanade methods are combined to yield an optical flow method that exhibits the local methods inherent in Lucas-Kanade techniques and the global methods inherent in the Horn-Schunck approach and its extensions. Often local methods are more robust under noise, while global techniques yield dense flow fields. See, for example, “Lucas/Kanade Meets Horn/Schunck: Combining Local and Global Optic Flow Methods,” Andrés Bruhn, Joachim Weickert, Christoph Schnörr, International Journal of Computer Vision, February 2005, Volume 61, Issue 3, pp 211-231, the entirety of which is hereby incorporated by reference herein.
Various embodiments of method 200 feature several advantages with respect to prior art systems and methods that generate intracardiac images and attempt to detect the locations of cardiac rhythm disorders or irregularities. A key underlying assumption of signal processing techniques that employ Hilbert Transform, Discrete Fourier Transforms (DFTs) or Fast Fourier Transforms (FFTs) is that the signal to be transformed is periodic. As is well known in the field of digital signal processing, this underlying basic assumption is frequently incorrect, and can lead to problems such as spectral leakage. Contrariwise, in some embodiments of method 200, an underlying assumption is that the electrical activity in a patient's heart is based upon ion channel activation, which is a stochastic and non-periodic process, and so strictly periodic behaviour is not assumed or required in subsequent data processing and manipulation steps.
Indeed, none of steps 210, 230, 240, or 250 of method 200 absolutely requires the use of Hilbert or Fourier transforms to process data. Instead, in some embodiments each of these steps can be carried out in the time domain without the need for frequency domain or quadrature conversion. For example, in step 210 the amplitudes of the various traces or electrograms can be normalized or adjusted in the time domain according to a selected standard deviation. In another example, rotors detected by method 200 are not assumed to be singularities in a phase map (as is assumed in techniques based upon frequency domain or Hilbert transform signal processing). This key difference also explains why the rotational direction of a rotor can be revealed or detected accurately by method 200 (and not at all, or very unsatisfactorily, using the frequency domain or Hilbert transforms of other methods employed to detect rotors). Note that in some embodiments, however, Hilbert, DFT and/or FFT signal processing components may be or are included in the data processing flow of method 200 (e.g., DSP filtering, deconvolution, etc.).
Referring now to
The data shown in
Described now is one embodiment and illustrative example of the first main step of the method 200 (normalization/adjustment/filtering of electrogram signals). Referring now to
Next, a sliding time window ranging between about 0.1 seconds and about to 1 second in length was applied to each filtered electrogram signal to generate individual amplitude-adjusted electrogram signals. (in some embodiments, the length of the sliding time window corresponds to, or is less than, the slowest repetition frequency expected to be present.) The resulting sliding-window amplitude-adjusted electrogram signals were then stored for later use to generate image backgrounds in velocity vector maps, where they could be used to show low amplitude areas indicative of valve defects/artifacts, loose electrode contact, and/or areas of fibrosis in the patient's myocardium. In the sliding-window amplitude-adjusted electrogram signals, the respective minima and maxima of each position of the sliding time window were used to normalize the amplitude values of all signals between zero and one (or 0 and 255 on an 8-bit integer numeric scale). Because the maximum and minimum values occurred at different time points for electrodes placed in different locations, this process yielded spatial information regarding action potential wave patterns for each sampled time point (more about which is said below).
Now I describe one embodiment and illustrative example of the second main step of the method 200 (generating three-dimensional electrogram surfaces for discrete times or time slices, or estimation of spatial wave shapes). The second step of method 200 takes the spatial distributions of all electrodes and their normalized voltage values at discrete times (e.g., the data represented by the box plots corresponding to selected discrete times within the selected time window over which electrogram signals were acquired and measured), and estimates or generates from such data or box plots corresponding to given discrete times respective continuous voltage surfaces (or action potential waveform estimates) in space. Because the electrode pattern density is limited, and depending on the method that is used to generate the estimated voltage surfaces, the estimated surfaces typically deviate to some extent from “true” surfaces. Such deviations are usually relatively small in magnitude, however, since the spatial size of the action potential wave given by its velocity (e.g., 0.5 to 1 m/sec.) times the action potential duration (e.g., 0.1 to 0.2 sec.) is much larger (e.g., 0.05 m) than the electrode spacing (e.g., about 1 mm to about 10 mm), and thus spatial aliasing generally does not occur. The electrode grid provided by catheter 110 thus permits relatively good estimates of action potential wave shapes or wavefronts in the form of smoothed electrogram surfaces to be obtained as they propagate across the myocardium. On the other hand, because of the fast sampling rate (which can, for example, range between about 0.25 milliseconds and about 8 milliseconds, and which in some embodiments is nominally about 1 millisecond), changes in the spatial shape or expression of the action potential wavefront from one sample to the next are typically relatively small (e.g., about 1 mm) compared to the electrode distances (which in some embodiments nominally range between about 2 mm and about 7 mm). Thus, method 200 is capable of detecting spatial changes in action potential wavefronts or wave shapes using time domain information (i.e., small amplitude changes between time samples) to estimate changes in the spatial domain (where relatively small shifts in action potentials occur at given electrode measurement locations).
One embodiment of a method for estimating action potential wavefronts or wave shapes employs an 8×8 rectangular electrode grid (e.g., TOPERA-like) model, which operates in two principal steps. First, each electrode/electrogram signal value at a discrete moment in time defines the height of its respective box in the “chess field” box plots shown in
Described now is one embodiment and illustrative example of the third main step of method 200 (generating a velocity vector map based on the electrogram surfaces). The third main step of method 200 uses the action potential wave shape estimates or electrogram surfaces generated at discrete times or time splices provided by the second main step to calculate a velocity vector map. For each sample interval a spatial wave shape or smoothed surface is calculated according to the second main step described above. Since the wave shapes differ only by a small delta between individual samples, and minimum and maximum values are normalized, shift vectors can be calculated at a spatial resolution that is higher than the spatial resolution of the electrodes (e.g., 30×30 samples). Since individual shifts between samples may differ according to random error, a velocity vector fit can be generated using 40 to 100 samples, where an average of observed shift vectors of the action potential wave shape care calculated. If the angle of a rotating wavefront is shifted by a few degrees per sample, the vector arrows will exhibit a circular pattern and in fact can resolve circles that are much smaller than inter-electrode distances. In one embodiment, the third main step of the method employs a vector pattern equation that best fits the observed movement of the evaluated spatial element or wavefront. In one embodiment that has been discovered to provide excellent results, and as described above, the velocity vector map is calculated using the Horn-Schunck optical flow method described above. That is, in one embodiment the Horn-Schunck optical flow method is used in the third main step of method 200 to estimate the velocity and direction of wavefronts or wave shapes between sampled times. Velocities of 40 to 100 samples are typically averaged to yield the most stable results.
Referring now to
At step 204, a high-pass filter is applied to the acquired EP data to remove DC offsets, as well as other undesirable low-frequency noise. In one embodiment, a 5 Hz high-pass filter is applied, although other filters, including band-pass filters, are contemplated, including, but not limited to, 10 Hz high-pass filters, 5-20 Hz band-pass filters, and 5-50 Hz band-pass filters. Notch- and low-pass filtering may also be applied in step 204. Hanning, trapezoidal and other digital filtering and/or Fast Fourier Transform (FFT) filtering techniques may also be applied.
At step 206, an average far-field electrogram signal is generated by stacking and averaging all electrogram traces. In the case of atrial EP recordings, the resulting estimate of a far-field ventricular depolarization is subtracted from each trace individually, thereby removing or at least reducing the far-field component therefrom.
At step 208, the amplitudes of individual filtered electrogram signals are normalized with respect to a given standard deviation occurring over a predetermined time window (e.g., a moving window of 200 samples around a time value “x”).
At step 212, a complete filtered sample array from the grid or basket catheter is provided as an output from first main step 210.
Referring now to
In
At step 244, Green's function, or another suitable surface generating method, is used to generate a surface of Z-values for each time slice or sampled time (more about which is said below). In one embodiment, the surface corresponding to the Z-values is smoothed.
At step 245, the calculated surface corresponding to each time slice or sampled time is provided as an output, with, for example, a 200×200 array of smoothed data points corresponding to the smoothed surface being provided for each time slice or sampled time. Note that in some embodiments the intervals at which time slices are selected, or the individual time slices themselves, may be predetermined, or may be selected automatically or by the user.
In
Referring now to
Discrimination between active and passive rotors is critical to making proper therapeutic decisions regarding the delivery of ablation therapy, which should only target structures underlying the drivers of atrial fibrillation (namely, active rotors only, and not passive rotors).
Next, the effects of typical artifact disturbances on the signals of the 64 channels of data shown In
Upon applying smoothed surface calculations and fitting (as shown in
The largest variation in results was seen at positions where the introduction of the artifacts and noise reduced relative amplitude values by the greatest amount, as indicated by the white areas shown in
In the white areas of
After confirming that method 200 was capable of detecting complex rotor structures accurately in a patient's myocardium—even in the presence of strong artifacts and noise—method 200 was applied to different time portions of the actual patient data shown in
As shown in
Differences between the results shown in
Thus, a health care professional can select differing time windows over which to apply method 200 to an EP mapping data set as a means of gaining a better understanding of the behavior of active and passive rotors, fibrotic regions, areas affected by valve defects or artifacts, breakthrough points and areas or defects that are at work in the patient's myocardium. The velocity vector maps generated by method 200 permit a health care professional to identify such cardiac rhythm disorders in a patient's myocardium with a degree of precision and accuracy that has heretofore not been possible using conventional EP mapping and intravascular basket or spline catheter devices and methods.
Referring now to
Referring now to
Data were acquired at a 1 millisecond rate over a time period of 60 seconds in all 64 channels.
The vector velocity map of
It will now be seen that method 200 provides not only rotational direction information, but also provides high-resolution spatial information regarding the presence and location of rotors despite the use of sparse electrode grid spacing. Rotors can also move over time in a patient's myocardium, even during the time interval over which EP mapping is being carried out. The increased spatial and temporal resolution of method 200 permits such shifts in rotor location to be detected.
In some embodiments, and as described above, multiple or different types of EP mapping and ablation catheters can be used sequentially or at the same time to diagnose and/or treat the patient. For example, a 64-electrode CONSTELLATION basket catheter can be used for EP mapping in conjunction with a PENTARAY16- or 20-electrode EP mapping catheter, where the PENTARAY EP mapping catheter is used to zero in on, and provide fine detail regarding, a particular region of the patient's myocardium that the basket catheter has revealed as the location of a source of a cardiac rhythm disorder or irregularity. In addition, catheter 110 or any other EP mapping catheter used in system 100 may be configured to provide ablation therapy (in addition to EP mapping functionality). The various catheters employed in system 100 may also include navigation elements, coils, markers and/or electrodes so that the precise positions of the sensing, pacing and/or ablation electrodes inside the patient's heart 10 are known. Navigational data can be employed by computer 300 in method 200 to provide enhanced estimates of the locations of the electrodes in the representations, maps or grids generated thereby, which in turn increases the accuracy and efficacy of the resulting velocity vector maps generated in method 200.
In another embodiment, computing device/system 300 is operably connected to a storage medium such as a hard drive or non-volatile memory located in, or operably connected to, data acquisition device 140, where computing device 300 is configured to trigger an external switch operably connected to data acquisition device 140 which permits the upload of conditioned electrogram signal data from data acquisition device 140 to computing device 300. According to such a configuration, computing device 300 and data acquisition device 140 can remain galvanically isolated from one another, and the need to physically swap USB memory sticks between data acquisition device 140 and computing device 300 is eliminated. This, in turn, permits system 100 to operate more efficiently and quickly, and to provide vector velocity maps to the health care professional in near-real-time while the EP mapping procedure is being carried out within the patient's heart 10.
In method 200, electrogram signals and processed data may be delivered or communicated to system 100, e.g., via a data carrier, after they have been acquired by the electrodes and stored for later processing. The various steps recited in the claims, and the sub-steps recited in each step, need not necessarily be carried out in the precise order in which they are recited.
The various systems, devices, components and methods described and disclosed herein may also be adapted and configured for use in electrophysiological mapping applications other than those involving the interior of a patient's heart, more about which is said below. These alternative applications can include internal or external EP mapping and diagnosis of a patient's epicardium or other portions of the patient's heart, a patient's spinal cord or other nerves, or a patient's brain or portions thereof.
Referring now to
Moreover, note that the various data processing steps described and disclosed above explicitly in connection with
There are now described in greater detail various embodiments of, and details concerning, electrographic flow (EGF) analysis, which broadly may employ some or many of the techniques and concepts described above. EGF analysis and mapping provides novel methods to identify Atrial Fibrillation (AF) drivers based on modeling electrical potential surfaces and subsequent flow analysis. Sources of excitation during AF can be characterized and monitored. Some of EGF embodiments described and disclosed below employ some of the data acquisition, processing and interpretation techniques described above, which are applied to the problem of efficiently and cost-effectively screening patients for atrial fibrillation without undertaking costly invasive medical procedures, such as EP mapping using intra-cardiac basket catheters.
Recent work in the field of atrial fibrillation using EGF techniques, conducted to further validate and test the various inventions described and disclosed herein, has revealed highly useful results. Described below in detail are recent results obtained using raw intra-cardiac EP mapping data that were originally obtained using conventional EP mapping techniques and systems (i.e., the TOPERA® cardiac arrhythmia mapping system), but which were subsequently processed and analyzed using the novel EGF techniques disclosed and described herein (hereafter “the EGF studies”). The original intra-cardiac EP mapping data were acquired from 108 patients in three different studies in hospitals located in Hamburg, Germany, Berlin, Germany, and Rotterdam, The Netherlands, using a conventional basket catheter system; namely, the aforementioned TOPERA system utilizing FIRMap catheters and RhythmView workstations. In the original TOPERA-based studies, focal impulse and rotor-mapping (FIRM) were performed in addition to pulmonary vein isolation. In the studies, one-minute epochs of unipolar electrograms were recorded using a 64-pole FIRMap basket catheter in both atria.
The aim of the retrospective EGF-based studies described herein was to evaluate the correlation between EGF velocities around given sources and their corresponding spatial variabilities (SV) and stabilities (SST). SST was calculated as a percentage of time over which a source was detected. AF sources identified with EGF mapping showed a wide range of SV and SST. Less stable AF sources with high spatial variability showed reduced excitation propagation velocity, while very stable AF sources displayed a high average velocity in their vicinity. Catheter ablation was shown to reduce the stability of sources and velocities, suggesting a role of these parameters in guidance of ablation.
More about these retrospective EGF studies is said below. However, some details regarding recent EGF-based studies may be found in the following publications:
Each of the foregoing Bellmann I, Bellmann II, and Bellmann III publications is hereby incorporated by reference herein, each in its respective entirety.
The EGF studies described and disclosed herein show that EGF techniques and analysis can be used as a powerful tool to characterize AF sources, and to sort patients into different types; namely, A-type patients, B-type patients, and C-type patients. A- and B-type patients are characterized by well-defined and steady EGF patterns and sources in the atria, which in some embodiments, and as described above, can be presented as 2D or 3D EGF maps. Contrariwise, C-type patients exhibit chaotic EGF patterns that do not exhibit stationary or stable sources in the atria. In the EGF studies, FIRM data from 108 patients with known outcomes were processed and analyzed using EGF technology.
The best predictor for outcome (freedom from AF) turns out to be EGF Source Activity at the end of each procedure (Final Activity). Source Activity is defined as the percent of active time per minute (or other suitable unit of time) that a leading source has been detected. EGF steadiness, E/s (or electrodes/second), a parameter relevant for the characterization of flow, and therefore finds use in patient stratification or classification (e.g., into A, B, or C types). Flow angle stability (FAS) over time, or flow angle stability per suitable unit of time, is another parameter that can be used to evaluate outcome or freedom from AF, and has proved to be a more useful predictor of outcome (freedom from AF) than steadiness or E/s.
EGF Source Activity, and how it is computed, requires no further explication. Obviously, different time periods can be used to estimate EGF Activity. Source Activity is the percentage of time a source is detectable. Final activity is the activity that is measured after all intra-cardiac ablation and PVI procedures have been completed.
Steadiness (or E/s) is essentially a measure of velocity (or the rate at which a detected signal moves from one electrode to another), and the consistency or steadiness thereof. If E/s is low, then detected flow signals are low in amplitude or inconsistent. If E/s is high, then detected flow signals are strong. Examples of low E/s values range between about 0 and about 5. Examples of high E/s values are those greater than about 10 or 15.
Flow angle stability (FAS) is computed by determining, for a given pixel or point in a flow or vector field, the angular displacement that occurs between successive time samples for the same pixel or point, over a given recording period (e.g., one minute, with each pixel being sampled, e.g. at a rate of 1 msec.). The maximum angular displacement that can occur between successive time samples in a sequence of vector fields, given a reference direction, is equal to π radians (or 180 degrees). FAS can be computed for each pixel or point in a flow field to produce an FAS map. Some examples of FAS values produced using 1 minute recordings and 1 msec. sample rates are: (a) about 0 to about π/4 for a high FAS (i.e., a very stable source that does not move much), and (b) about π/4 to about π/2 for an unstable, chaotic, or highly variable source.
EGF Activity levels combined with, for example, one or more of the number detected sources, the activity of detected sources, the flow angle stability of detected sources, and the steadiness of detected sources permits a classification of patients into three types (A, B and C). A- and B-type patients (e.g., 56% of analyzed patient population) significantly benefited from source ablation in addition to PVI, and exhibited an increase in freedom from AF after 12 months, rising from 19% to 81% (p value=0.0000016). C-type patients (44% of analyzed patient population) showed no significant source ablation benefit after successful PVI. Moreover, in C-type patients, source ablation had no significant effect, and on average these patients exhibited 73% freedom from AF after 12 months. In other words, there is no need or benefit for most C-type patients to undergo either: (a) invasive intra-cardiac basket catheter EP mapping procedures, or (b) intra-cardiac ablation procedures (more about which is said below).
The EGF studies and the corresponding EGF technology employed therein are now described in further detail.
Tables 1 and 2 below set forth further data and statistics regarding the pilot study conducted in Hamburg.
In the validation studies conducted with 78 patients in Berlin and Rotterdam, patients were once again sorted and classified according to Final Activity, and the following results were obtained:
Final activity>25%:
Final activity 25% to 20%:
Final activity<20%:
Tables 3 and 4 show some data from the validation studies. From among the 78 patients in the validation study, 45 patients were classified as A- or B-type patients (58% of the validation study population). Table 3 data represent 29 patients where: (a) FIRM ablation was not effective (Final Activity>25% and Steadiness>10); (b) 14% of patients exhibited freedom from AF/AT after 3, 6 and 12 months, and 69% of patients suffered a recurrence of AF/AT after 12 months. Table 4 data represent 16 patients where: (a) FIRM ablation was effective (Final Activity<25% or Steadiness<10); (b) 75% of the 16 patients were free from AF/AT after 3, 6 and 12 months (p=0.00004); and (c) 0% of the 16 patents suffered a recurrence of AF/AT after 12 months (p=0.00015).
In the validation studies, patients were classified as A-, B- or C-type patients according to the following criteria:
Maximal Activity of leading source>25% and Steadiness>10 E/s
Maximal Activity of leading source<25% or
<Spatial Variability or Steadiness<10 E/s).
The data in Tables 3 and 4 indicate that source ablation of A- and B-type patients significantly improves outcomes. Moreover, the validation studies confirm the strong correlation discovered in the pilot study between outcome and Final Activity.
Additionally, and referring to
Referring now to
In
In
Some examples of current manufacturers of cardiac monitoring patches include: (a) iRhythm® and their Zio XT® and Zio AT® Patch product offerings; (b) the Bardy Dx® Camation Ambulatory Monitor (CAM™), and (c) the NUVANT® Mobile Cardiac Telemetry (MCT) Monitor, which communicates wirelessly with a cellular device. See, for example: (1) U.S. Pat. No. 10,123,703 entitled “Health monitoring apparatus with wireless capabilities for initiating a patient treatment with the aid of a digital computer” to Bardy et al. (“the '703 patent”); (2) U.S. patent No. 10,299,691 entitled “Wearable monitor with arrhythmia burden evaluation” to Hughes et al. (“the '691 patent”); (3) U.S. Pat. No. 10,772,522 entitled “Disposable biometric patch device” to Zadig, and (4) “Cardiac Ambulatory Monitoring: New Wireless Device Validated Against Conventional Holter Monitoring in a Case Series” to Murali et al., Front. Cardiovasc. Med., 30 Nov. 2020 (https://doi.org/10.3389/fcvm.2020.587945) describing the SmartCardia® wearable cardiac monitoring patch (“the Murali paper”). Those skilled in the art will realize that certain aspects and features disclosed and described in in the '703 patent, the '691 patent, the '522 patent, and the Murali paper can be employed in, or adapted and modified for use in, the systems, devices, components, and methods described and disclosed herein. The '703 patent, the '691 patent, the '522 patent, and the Murali paper incorporated by reference herein, each in its respective entirety. Apple iWatch®, FitBit®, Galaxy Watch3®, and Galaxy Watch Active2® are examples of watch or watch-like devices configured to acquire cardiac data from the wearer, such as ECGs, blood pressure, heart rate, etc. Such wearable devices likewise contain certain aspects and features that can be employed in, or adapted and modified for use in, the systems, devices, components, and methods described and disclosed herein.
In the example of
Continuing to refer to
It is further contemplated that body surface electrodes 430 may be mounted, attached or coupled to the patient's thorax by means other than a vest, such as by patches, electrode strips, individually, or by other means known in the art. For example, electrode strips manufactured by Goltec GmbH of Cremlingen, Germany can be used. Carbon and metal body surface electrode strips are available from Goltec GmbH. Carbon electrode strips have the advantage of being radio-translucent, i.e., being transparent or substantially transparent during X-ray imaging.
Electrodes may be provided only on the anterior portion of the patient's thorax, only on the posterior portion of the patient's thorax, on side or lateral portions of the patient's thorax, or on any suitable combination of anterior, posterior and/or lateral portions of the patient's thorax.
Continuing to refer to
Still referring to
In addition to sensing electrodes 430, other types of devices and/or transducers, such as ground electrodes, navigation patches, position markers, or other devices may be configured to operate in conjunction with, be incorporated into, or form a portion of vest 420, electrodes 430, and/or system 10. Electrodes 430 may be reusable or disposable, unipolar or bipolar, and may be configured for use with MRT/MRI, X-Ray, and/or CAT scanning imaging systems or other types of imaging systems 60.
Note that in some embodiments, system 100 of
The embodiment of system 100 shown in
Computer or computing device 300 may be configured to receive operator inputs from an input device 320 such as a keyboard, mouse and/or control panel. Outputs from computer 300 may be displayed on display or monitor 324 or other output devices (not shown in
During body surface EP mapping or EGF analysis procedures, and as described above, body surface electrodes 430 are positioned on the thorax of patient 5, and by way of example may be mounted on a vest 420 that is configured to place individual electrodes 430 in predetermined positions on the patient's body. These predetermined electrode positions can also be provided to imaging and/or navigation system 60 and/or to computer 300 as a data file so that the spatial positions of body surface electrodes 430 are known (at least approximately), and so that EGF analysis can be carried out accordingly as described above in connection with intra-cardiac EGF analysis (e.g., as described above in connection with
When system 100 of
Note that in some embodiments of system 100 shown in
Referring now to
By way of non-limiting example, body surface electrodes 430 may be clustered or more densely positioned on those portions of a patient's thorax that are expected to yield, or that are measured to yield, the best or optimum fidelity body surface electrogram signals corresponding to signals originating in a patient's atrium, the two atria, or any other target portion of the patient's heart 10 that is to be analyzed. For example, body surface electrodes 430 can be concentrated on the anterior portion of the patient's thorax in the region where quadrants I, II, III and IV intersect near the middle of the thorax, or at a location slightly upwards from, or slightly upwards and to the left from, such intersection. Note that electrodes 430 can be arranged on the patient's thorax in any suitable pattern or configuration, including, but not limited to, an array of rows and columns (as shown in
In one embodiment, body surface electrogram signal data are processed by computer 300 to produce a display showing the location(s) of the source(s) of cardiac rhythm disorders and/or irregularities in the patient's heart 10 in real-time or near-real-time, further details of which are provided below. That is, at and between the sampled locations of the patient's endocardium, computer 300 may be configured to compute and display in real-time or near-real-time an estimated, detected and/or determined location(s) of the site(s), source(s) or origin)s) of the cardiac rhythm disorder(s) and/or irregularity(s) within the patient's heart 10. This permits a medical practitioner to select interactively and quickly the electrodes 430 of vest 420 that are best detecting the location of the source(s) of the cardiac rhythm disorder or irregularity. Note that in some embodiments, EGF techniques are utilized to analyze body surface electrogram signal data without having to resort to complicated, lengthy and computationally-intensive tomographic or reverse modelling computations. In some applications, all that is required is to determine whether sources of AF and/or AT are present in a patient's atrium or atria, and whether those sources are stable or unstable. In other embodiments, and assuming sufficient computational power is available to process the acquired body surface electrogram signals, reverse modelling (e.g., “solving the reverse problem”), downward continuation, and/or employing tomographic techniques using a three-dimensional grid of voxels may be employed to yield higher fidelity and more accurate EGF results.
Referring once again to
In some embodiments, the rate at which individual body surface electrogram and/or ECG signals are sampled and acquired by system 100 can range between about 0.25 milliseconds and about 8 milliseconds, and may be about 0.5 milliseconds, about 1 millisecond, about 2 milliseconds or about 4 milliseconds. Other sample rates are also contemplated. While in some embodiments system 100 is configured to provide unipolar signals, in other embodiments system 100 is configured to provide bipolar signals.
In one embodiment, system 100 can include a BARD® LABSYSTEM™ PRO EP Recording System, which is a computer and software driven data acquisition and analysis tool designed to facilitate the gathering, display, analysis, pacing, mapping, and storage of intracardiac EP data. Also in one embodiment, data acquisition device 140 can include a BARD® CLEARSIGN™ amplifier, which is configured to amplify and condition electrocardiographic signals of biologic origin and pressure transducer input, and transmit such information to a host computer (e.g., computer 300 or another computer).
Computing device or computer 300 is suitably configured and programmed to receive or access the body surface electrogram signals provided by body surface electrodes 430. Computer 300 is further configured to analyze or process such electrogram signals in accordance with the methods, functions and logic disclosed and described herein so as to permit reconstruction of cardiac activation information from the electrogram signals using EGF techniques. This, in turn, makes it possible to locate with at least some reasonable degree of precision the location of the source of a heart rhythm disorder or irregularity. Once such a location has been discovered—or not discovered—the characteristics of the source(s) may be analyzed and the therapy, if any, that is to be delivered to the patient may be determined.
In one embodiment, and as shown in
Medical navigation systems suitable for use in the various embodiments described and disclosed herein include, but are not limited to, image-based navigation systems, model-based navigation systems, optical navigation systems, electromagnetic navigation systems (e.g., BIOSENSE® WEBSTER® CARTO® system), and impedance-based navigation systems (e.g., the St. Jude® ENSITE™ VELOCITY™ cardiac mapping system), and systems that combine attributes from different types of imaging AND navigation systems and devices to provide navigation within the human body (e.g., the MEDTRONIC® STEALTHSTATION® system).
Referring now to
With reference to the foregoing discussion and the Figures relating thereto (i.e.,
In one embodiment, there is provided a system configured to detect at least one location of at least one source of at least one cardiac rhythm disorder in a patient's heart, the system comprising: (a) at least one computing device; (b) at least one data acquisition device operably connected to the at least one computing device or configured to provide as outputs therefrom body surface electrogram signals; (c) a plurality of body surface electrodes configured to generate body surface electrogram signals and for placement on the patient's body surface, the plurality of body surface electrodes being operably connected to the at least one data acquisition device, and (d) a display or monitor operably connected to the at least one computing device and configured to visually display to the user one or more vector maps generated by the at least one computing device; wherein the computing device comprises at least one non-transitory computer readable medium configured to store instructions executable by at least one processor to determine the at least one location of the at least one source of the at least one cardiac rhythm disorder in the patient's heart, the computing device being configured to: (i) receive the body surface electrogram signals from the plurality of body surface electrodes located on the patient's body, where amplitudes of the body surface electrogram signals received by the at least one computing device have been at least one of conditioned, amplified, normalized, filtered, and adjusted by the data acquisition device before being provided to the computing device; (ii) assign or relate positional data corresponding to predetermined positions of the body surface electrodes on the patient's body to their respective corresponding body surface electrogram signals and body surface electrodes; (iii) generate at least one spatial map of the body surface electrode positions; (iv) for each or selected discrete times over which the body surface electrogram signals are being processed, process the amplitude-adjusted body surface electrogram signals to generate a plurality of electrogram surfaces or data grids, each such surface or data grid corresponding at least partially to the at least one spatial map, at least one surface or data grid being generated for each such time, and (v) process the plurality of electrogram surfaces or data grids through time to generate at least one vector map corresponding at least partially to the spatial map, the at least one vector map being configured to reveal the at least one location of the at least one source of the at least one cardiac rhythm disorder, the at least one vector map being shown to the user on the display or monitor.
The foregoing embodiment can further comprise: (1) the plurality of electrogram surfaces being a plurality of three-dimensional electrogram surfaces that includes a first three-dimensional electrogram surface corresponding to a first EGF recording of a first duration of time and a second three-dimensional electrogram surface corresponding to a second EGF recording of a second duration of time, the second duration of time being greater than the first duration of time; (2) the first and second three-dimensional electrogram surfaces facilitating a determination of whether the patient's AF revealed in the velocity vector or EGF map is characterized by one or more of: (a) atrial behavior exhibiting spatially and temporally stable rotors, drivers or sources (Type A); (b) atrial behavior where spatially stable rotors switch on and off (Type B), and (c) chaotic atrial behavior in which the rotors are spatially and temporally variable (Type C); (3) the first duration of time ranging between about 0.5 seconds and about 30 seconds, between about 1 second and about 5 seconds, or between about 1 second and about three seconds; (4) sources being detected over a duration of between about 0.5 seconds and about 30 seconds, or between about 1 second and about 15 seconds; (5) the second duration of time ranging between about 1 minute and about 3 minutes, between about 30 seconds and about 10 minutes, or between about 15 seconds and about 20 minutes; (6) the vector map being a velocity vector map; (7) at least one of an activity value, a flow angle stability value, and a steadiness value being generated by the computing device for one or more sources corresponding to the at least one cardiac rhythm disorder revealed in the vector map; (8) at least one of the activity value, the flow angle stability value, and the steadiness value being displayed on the display or monitor, (9) on the basis of at least one of the generated activity values, flow angle stability values, and steadiness values the computing device determining whether to classify the patient as an A-type patient, a B-type patient, or a C-type patient; (10) the computing device being configured to determine whether the at least one velocity vector map corresponds to an A-type patient, a B-type patient, or a C-type patient; (11) the electrogram surfaces or data grids comprising at least one three-dimensional surface; (12) the electrogram surfaces or data grids being generated by the computing device using Green's function; (13) the vector map generated by the computing device being configured to reveal a location in the patient's heart of one or more of: (a) an active rotor; (b) a passive rotor; (c) a breakthrough point, and (d) a focal point; (14) the velocity vector map being generated by the computing device using at least one optical flow analysis technique; (15) the at least one optical flow analysis technique being selected from the group consisting of a Horn-Schunck method, a Buxton-Buston method, a Black-Jepson method, a phase correlation method, a block-based method, a discrete optimization method, a Lucas-Kanade method, and a differential method of estimating optical flow; (16) the at least one processor and the at least one non-transitory computer readable medium being configured to determine, using a trained atrial discriminative machine learning model, predictions or results concerning atrial fibrillation in the patient's heart; (17) the trained atrial discriminative machine learning model having been trained at least partially using data obtained from a plurality of other previous patients, where intracardiac electrophysiological (EP) mapping signals for the other patients have been processed using electrographic flow (EGF) methods to detect at least one of: (I) the presence of sources of atrial fibrillation in the other patients' hearts; (II) the locations of sources of atrial fibrillation in the other patients' hearts; (III) the activity levels of sources of atrial fibrillation in the other patients' hearts; (IV) the spatial variability levels of sources of atrial fibrillation in the other patients' hearts; (V) the flow angle stability levels of sources of atrial fibrillation in the other patients' hearts; and (VI) the classification of patients as at least one of types A, B and C; (18) paired data sets of body surface electrogram signals and the intracardiac EP mapping signals having been acquired simultaneously from at least some of the plurality of other patients and the paired data sets have been correlated to one another using the trained atrial discriminative machine model; (19) the trained atrial discriminative machine learning model being further configured to generate one or more of the following predictions or results for the patient using the conditioned electrogram signals and positional data corresponding to the patient: (1) Does the patient have atrial fibrillation or not? (2) If the patient has atrial fibrillation, determining at least one of the spatial variability level, the activity level, and the flow angle stability level associated with one or more sources detected in the patient's heart; (3) If the patient has atrial fibrillation, determining the locations of one or more sources detected in the patient's heart; (4) If the patient has atrial fibrillation, whether one or more activation sources detected in the patient's heart are characterized by chaotic flow; and (5) classification of the patient as one of types A, B and C, and (20) the computing device being further configured to: (iv) process the conditioned electrogram data and positional data in the trained machine learning model to generate the one or more predictions or results; and (v) display the one or more predictions or results on the display or monitor to the user.
In another embodiment, there is provided a method of detecting at least one location of at least one source of at least one cardiac rhythm disorder in a patient's heart using a system comprising at least one computing device, the computing device comprising at least one non-transitory computer readable medium configured to store instructions executable by at least one processor to determine the at least one location of the at least one source of the at least one cardiac rhythm disorder in the patient's heart, the system further comprising a plurality of body surface electrodes operably connected to the computing device through a data acquisition device and a monitor or screen operably connected to the computing device, the method comprising: (a) acquiring body surface electrogram signals using the body surface electrodes located on one or more body surfaces of the patient; (b) using at least one of the computing device and the data acquisition device, at least one of conditioning, filtering, normalizing and adjusting the amplitudes of the acquired body surface electrogram signals; (c) using the computing device, assigning positions or identifiers for each of the body surface electrodes to corresponding individual body surface electrogram signals; (d) using the computing device and the assigned positions or identifiers, providing or generating a spatial map of the body surface electrode positions; (e) using the computing device, for each or selected discrete times over which the body surface electrogram signals are being processed, processing the amplitude-adjusted body surface electrogram signals to generate a plurality of electrogram surfaces or data grids corresponding at least partially to the spatial map, one surface or data grid being generated for each such time, and (f) using the computing device, processing the plurality of electrogram surfaces or data grids through time to generate a vector map corresponding at least partially to the spatial map, the vector map being configured to reveal on the monitor or display to a user the at least one location of the at least one source of the at least one cardiac rhythm disorder.
The foregoing embodiment can further comprise: (1) conditioning the electrogram signals further comprises one or more of amplifying the electrogram signals, notch filtering the electrogram signals, and bandpass, low-pass or high-pass filtering the body surface electrogram signals; (2) generating the electrogram surfaces or data grids using Green's function; (3) showing the at least one cardiac rhythm disorder as an active rotor, a passive rotor, a breakthrough point, or a focal point on the vector map; (4) generating the vector map using at least one optical flow analysis technique; (5) the at least one optical flow analysis technique being selected from the group consisting of a Horn-Schunck method, a Buxton-Buston method, a Black-Jepson method, a phase correlation method, a block-based method, a discrete optimization method, a Lucas-Kanade method, and a differential method of estimating optical flow, and (6) the method further comprising detecting at least one property or characteristic of the at least one source of at least one cardiac rhythm disorder in a patient's heart using the system, where the property or characteristic is, by way of for example, a location, an activity level, a steadiness level, a flow angle stability level, or other property or characteristic disclosed or described herein.
Referring now to
Now described are more specific examples of machine learning systems, methods applied to the problem of accurately predicting the presence or classification of cardiac rhythm disorders in a patient's heart based upon input surface body electrode data only (in combination with a trained atrial discriminative machine learning model).
With reference now to
In accordance with the teachings and disclosures set forth above and in the Figures, patients who are determined to be C-type patients using the body surface and intracardiac electrode machine learning system described and disclosed herein can be spared the trouble, risk, cost and expense associated with undergoing very likely unnecessary but expensive intra-cardiac EP mapping and/or ablation or PVI procedures that would be unlikely to do anything to improve their state of health. Further in accordance with the teachings and disclosures set forth above and in the Figures, and in contrast, patients who are determined to be A- or B-type patients using the body surface and intracardiac electrode machine learning system described and disclosed herein would be good candidates for intra-cardiac EP mapping and/or ablation or PVI procedures that are very likely to provide them with beneficial results.
Continuing to refer to
Still continuing to refer to
As shown in
The prediction of the machine learning model is then ŷ=fW(x) (or “f of x, parametrized by W′). This prediction should be as close as possible to y. During training, parameters W are optimized so as to minimize the error in estimating y. Such an error can be described as a loss function L(y, ŷ), for example the modulus of the difference L(y, ŷ)=∥y−ŷ∥. Which is carried out in block LM, as described above.
Since the target values y are derived from intracardiac electrodes located in only one atrium, but body surface electrodes pick up signals x from both atria, a mechanism is needed to compensate for this. The idea behind atrial discriminative training (ADT) is to ask the machine learning model to make two predictions: fW(x)=(ŷL, ŷR), one for each atrium. However, the ground truth y from the intracardiac recording is only known for one atrium (y=yL or y=yR). The cost function therefore separates the two predictions into L(y, ŷ)=a L(yL, ŷL)+βL(yR, ŷR) and the coefficients are set according to the locations of the intracardiac recordings: (α, β)=(1,0) ify=yL and (α, β)=(0, 1) if y=yR.
As a result, at training time, the machine learning model does not know which atrium it is supposed to predict, and predictions for the atrium that was not measured intracardially are not penalized. At test time, the machine learning model will be able to make predictions for both atria simultaneously. Consequently, the foregoing systems and methods can be used to localize and quantify drivers of AF.
It will now be seen that an ADT MLM can be trained to directly predict optical flow from two different input images, which correspond to: (a) optical flow images derived from intra-cardiac EP data: and (b) optical flow images derived from body surface EP data acquired at the same time and from the same patients. Training data need not be perfect or noise free.
After having read and understood the present specification, drawings and claims, those skilled in the art will now understand that configurations and architectures of MLMs other than those explicitly described and disclosed herein can also be used obtain similarly useful results. Moreover, and with reference to
With respect to the foregoing atrial discriminative machine learning models, and the systems, devices, components, and methods associated therewith, the following additional embodiments, features, and aspects are also contemplated.
In one embodiment, there is provided a system configured to determine and display to a user one or more predictions or results concerning atrial fibrillation in a patient's heart, the system comprising: (a) at least one computing device; (b) at least one data acquisition device operably connected to the at least one computing device or configured to provide as outputs therefrom body surface electrogram signals; (c) a plurality of body surface electrodes configured to generate body surface electrogram signals and for placement on the patient's body surface, the plurality of body surface electrodes being operably connected to the at least one data acquisition device, and (d) a display or monitor operably connected to the at least one computing device and configured to visually display to the user the predictions or results concerning the atrial fibrillation generated by the at least one computing device; wherein the computing device comprises at least one processor and at least one non-transitory computer readable medium configured to store instructions executable by the at least one processor to determine, using a trained atrial discriminative machine learning model, the predictions or results concerning atrial fibrillation in the patient's heart, the computing device being configured to: (i) receive the body surface electrogram signals from the plurality of body surface electrodes located on the patient's body, where the body surface electrogram signals received by the at least one computing device have been at least one of conditioned, amplified, normalized, filtered, and adjusted by the data acquisition device before being provided to the computing device as conditioned electrogram signals; (ii) assign or relate positional data corresponding to positions or estimated positions of the body surface electrodes on the patient's body to their respective corresponding body surface electrogram signals and body surface electrodes; (iii) input the conditioned electrogram signals and positional data into the trained atrial discriminative machine learning model, where the trained atrial discriminative machine learning model has been trained at least partially using data obtained from a plurality of other previous patients, where intracardiac electrophysiological (EP) mapping signals for the other patients have been processed using electrographic flow (EGF) methods to detect at least one of: (1) the presence of sources of atrial fibrillation in the other patients' hearts; (11) the locations of sources of atrial fibrillation in the other patients' hearts; (III) the activity levels of sources of atrial fibrillation in the other patients' hearts; (IV) the spatial variability levels of sources of atrial fibrillation in the other patients' hearts; (V) the flow angle stability levels of sources of atrial fibrillation in the other patients' hearts; and (VI) the classification of patients as at least one of types A. B and C; where paired data sets of body surface electrogram signals and the intracardiac EP mapping signals have been acquired simultaneously from at least some of the plurality of other patients and the paired data sets have been correlated to one another using the atrial discriminative trained machine model, and the trained atrial discriminative machine learning model is further configured to generate one or more of the following predictions or results for the patient using the conditioned electrogram signals and positional data corresponding to the patient: (1) Does the patient have atrial fibrillation or not? (2) If the patient has atrial fibrillation, determining at least one of the spatial variability level, the activity level, and the flow angle stability level associated with one or more sources detected in the patient's heart; (3) If the patient has atrial fibrillation, determining the locations of one or more sources detected in the patient's heart; (4) If the patient has atrial fibrillation, whether one or more activation sources detected in the patient's heart are characterized by chaotic flow; and (5) classification of the patient as one of types A, B and C; and further wherein the computing device is configured to: (iv) process the conditioned electrogram data and positional data in the trained machine learning model to generate the one or more predictions or results; and (v) display the one or more predictions or results on the display or monitor to the user.
The foregoing embodiment can further comprise: (1) a trained atrial discriminative machine learning model configured to provide the results or predictions therefrom to a loss function module; (2) a loss function module configured to provide outputs based on the results or predictions provided by the trained atrial discriminative machine learning model back to the trained atrial discriminative machine learning model to facilitate optimizing results or predictions subsequently provided thereby; (3) predictions or results generated by an atrial discriminative machine learning model comprising one or more of: (a) the patient has no detectable atrial fibrillation at the present time; (b) the patient has a type of atrial fibrillation having a substantial probability of being treated successfully with pulmonary vein isolation alone; (c) the patient has a type of atrial fibrillation that has a substantial probability of being treated successfully only with atrial ablation or with atrial ablation in combination with pulmonary vein isolation; and (d) providing an estimate of the probability of recurrence of atrial fibrillation in the patient; (4) predictions or results generated by the atrial discriminative machine learning model comprising one or more of: (a) the estimated locations of one or more sources or rotors in the patient's heart; (b) whether one or more sources or rotors in the patient's heart are located in a right atrium or a left atrium of the patient; (c) at least one type of source or rotor in the patient's heart, including active rotors or sources, passive rotors or sources, focal points, breakthrough points, and chaotic rotors or sources; (d) activity levels of one or more sources or rotors in the patient's heart; (d) spatial variability levels of one or more sources or rotors in the patient's heart, and (e) flow angle stabilities of one or more sources or rotors in the patient's heart; (5) a trained atrial discriminative machine learning model being updated at least partially using data obtained from a plurality of new patients, where paired data sets of body surface electrogram signals and intracardiac electrophysiological (EP) mapping signals have been acquired simultaneously from each of the plurality of new patients, and the paired data sets have been correlated to one another using machine learning; (6) a trained atrial discriminative machine learning model is updated or trained at least partially using MRI data obtained from a plurality of new patients, where areas or regions of fibrosis in the plurality of new patients have been identified in the MRI data and are correlated using machine learning to one or more of the body surface electrogram signals and the EP mapping signals; (7) a trained atrial discriminative machine learning model is updated or trained at least partially using one or more of body surface electrogram data and intracardiac EP mapping signals obtained from a plurality of new patients, where a first portion of the new patients have no atrial fibrillation and are identified in the data as being atrial-fibrillation-free, and a second portion of the new patients have atrial fibrillation and are identified in the data as having atrial fibrillation, and the paired data sets have been correlated to one another using machine learning; (8) a trained atrial discriminative machine learning model being updated or trained at least partially using body surface electrogram data and intracardiac EP mapping signals obtained from a plurality of new patients determined to have atrial fibrillation prior to being treated by intra-cardiac ablation, where body surface electrogram data and intracardiac EP mapping signals are obtained from the plurality of new patients before and after atrial ablation procedures are performed in at least one atrium of each such new patient, and the resulting body surface electrogram data and intracardiac EP mapping signals have been correlated to one another using machine learning; (9) a trained atrial discriminative machine learning model being updated or trained at least partially using body surface electrogram data and intracardiac EP mapping signals obtained from a plurality of new patients determined to have had atrial fibrillation previously, who were treated with a pulmonary vein isolation procedure previously, and who have been atrial-fibrillation-free for at least one year after being treated by the pulmonary vein isolation procedure, where body surface electrogram data and intracardiac EP mapping signals have been obtained from the plurality of new patients before and one year after the pulmonary vein isolation procedures, and the resulting body surface electrogram data and intracardiac EP mapping signals have been correlated to one another using machine learning; (10) a trained atrial discriminative machine learning model being updated or trained at least partially using simulated body surface electrograms generated using a heart and torso model having one or more known origins of rotors or sources in one or more atria thereof; (11) a trained atrial discriminative machine learning model being updated or trained at least partially using data from a plurality of patients, where the data from the patients relate to one or more of atrial volume, atrial dimensions, patient age, patient weight, patient height, and patient body mass index; (12) a trained atrial discriminative machine learning model comprising one or more of: (a) a neural network, (b) a generative neural network; (c) a recurrent neural network, and (d) a feed-forward neural network; (13) a trained atrial discriminative machine learning model comprising a recurrent neural network employing long short-term memory (LSTM); (14) a trained atrial discriminative machine learning model comprising one or more of: (a) a nearest neighbor model; (b) a naive Bayes model; (c) a decision tree model; (d) a linear regression model; (e) a support vector machine (SVM) model, and (f) a neural network; (15) a trained atrial discriminative machine learning model being generated at least partially using supervised learning or unsupervised learning; (16) a trained atrial discriminative machine learning model comprising convolutional layers; (17) conditioned electrogram signals being processed by the at least one computing device to remove or substantially remove at least portions of the QRS or QRST complex from at least some of the electrogram signals; (18) Green's function being employed in the EGF methods; and (19) EGF methods including at least one optical flow analysis technique selected from the group consisting of a Horn-Schunck method, a Buxton-Buston method, a Black-Jepson method, a phase correlation method, a block-based method, a discrete optimization method, a Lucas-Kanade method, and a differential method of estimating optical flow.
In another embodiment, there is provided a method of determining and displaying to a user one or more predictions or results concerning atrial fibrillation in a patient's heart using a system comprising at least one computing device, at least one data acquisition device operably connected to the at least one computing device or configured to provide as outputs therefrom body surface electrogram signals, a plurality of body surface electrodes configured to generate body surface electrogram signals and for placement on the patient's body surface, the plurality of body surface electrodes being operably connected to the at least one data acquisition device, and a display or monitor operably connected to the at least one computing device and configured to visually display to the user the predictions or results concerning the atrial fibrillation generated by the at least one computing device, the computing device comprising at least one processor and at least one non-transitory computer readable medium configured to store instructions executable by the at least one processor to determine, using a trained atrial discriminative machine learning model, the predictions or results concerning atrial fibrillation in the patient's heart, the method comprising: (a) acquiring body surface electrogram signals using the body surface electrodes located on one or more body surfaces of the patient; (b) using at least one of the computing device and the data acquisition device, at least one of conditioning, filtering, normalizing and adjusting the amplitudes of the acquired body surface electrogram signals; (c) using the computing device, assigning positions or identifiers for each of the body surface electrodes to corresponding individual body surface electrogram signals; (d) using the computing device and the assigned positions or identifiers, providing or generating a 2D or 3D spatial map of the body surface electrode positions; (e) using the computing device and the trained atrial discriminative machine learning model, inputting the conditioned electrogram signals and positional data into the trained atrial discriminative machine learning model, where the trained atrial discriminative machine learning model has been trained at least partially using data obtained from a plurality of other previous patients, intracardiac electrophysiological (EP) mapping signals for the other patients have been processed using electrographic flow (EGF) methods to detect at least one of the presence of sources of atrial fibrillation in the other patients' hearts, the locations of sources of atrial fibrillation in the other patients' hearts, the activity levels of sources of atrial fibrillation in the other patients' hearts, the spatial variability levels of sources of atrial fibrillation in the other patients' hearts, the flow angle stability levels of sources of atrial fibrillation in the other patients' hearts, and the classification of patients as at least one of types A, B and C, where paired data sets of body surface electrogram signals and intracardiac electrophysiological (EP) mapping signals have been acquired simultaneously from at least some of the plurality of other patients and the paired data sets have been correlated to one another using machine learning, and the trained atrial discriminative machine learning model is to generate one or more of the following predictions or results: (1) Does the patient have atrial fibrillation or not? (2) If the patient has atrial fibrillation, determining at least one of the spatial variability level, the flow angle stability level, and the activity level associated with one or more sources detected in the patient's heart, (3) If the patient has atrial fibrillation, determining the locations of one or more sources detected in the patient's heart; (4) If the patient has atrial fibrillation, whether one or more sources detected in the patient's heart are characterized by chaotic behavior; (f) processing the conditioned electrogram data and positional data in the trained machine learning model to generate the one or more predictions or results; and (g) displaying the one or more predictions or results on the display or monitor to the user.
The foregoing embodiment can further comprise: (1) a trained machine learning model having been trained at least partially using data obtained from the plurality of other previous patients, where intracardiac electrophysiological (EP) mapping signals for the other patients have been processed using electrographic flow (EGF) methods to detect at least one of the presence of sources of atrial fibrillation in the other patients' hearts, the locations of sources of atrial fibrillation in the other patients' hearts, the activity levels of sources of atrial fibrillation in the other patients' hearts, the spatial variability levels of sources of atrial fibrillation in the other patients' hearts, and the flow angle stability levels of sources of atrial fibrillation in the other patients' hearts (2) generating predictions or results using the machine learning model that comprise one or more of: (a) the patient has no detectable atrial fibrillation at the present time; (b) the patient has a type of atrial fibrillation having a substantial probability of being treated successfully with pulmonary vein isolation alone; (c) the patient has a type of atrial fibrillation that has a substantial probability of being treated successfully only with atrial ablation or with atrial ablation in combination with pulmonary vein isolation; (d) providing an estimate of the probability of recurrence of atrial fibrillation in the patient; (3) generating predictions or results using the machine learning model that comprise one or more of: (a) the estimated locations of one or more sources or rotors in the patient's heart; (b) whether one or more sources or rotors in the patient's heart are located in a right atrium or a left atrium of the patient; (c) at least one type of source or rotor in the patient's heart, including active rotors or sources, passive rotors or sources, focal points, breakthrough points, and chaotic rotors or sources; (d) activity levels of one or more sources or rotors in the patient's heart; (e) spatial variability levels of one or more sources or rotors in the patient's heart, and (f) flow angle stability levels of one or more sources or rotors in the patient's heart; (4) updating or training the trained machine learning model at least partially using MRI data obtained from a plurality of new patients, where areas or regions of fibrosis in the plurality of new patients have been identified in the MRI data and have been correlated using machine learning to one or more of body surface electrogram signals and EP mapping signals acquired from the plurality of new patients; (5) updating or training the trained machine learning model at least partially using one or more of body surface electrogram data and intracardiac EP mapping signals obtained from a plurality of new patients, where a first portion of the new patients have no atrial fibrillation and are identified in the data as being atrial-fibrillation-free, and a second portion of the new patients have atrial fibrillation and are identified in the data as having atrial fibrillation, and the paired data sets have been correlated to one another using machine learning; (6) updating or training the trained machine learning model at least partially using MRI data obtained from at least some of the plurality of new patients, and areas or regions of atrial fibrosis have been identified in the MRI data for such new patients, and the MRI data concerning areas or regions of fibrosis have been correlated to one or more of the body surface electrogram signals and the EP mapping signals using machine learning; (7) updating or training the trained machine learning model at least partially using body surface electrogram data and intracardiac EP mapping signals obtained from a plurality of new patients determined to have atrial fibrillation prior to being treated by intra-cardiac ablation, where body surface electrogram data and intracardiac EP mapping signals are obtained from the plurality of new patients before and after atrial ablation procedures are performed in at least one atrium of each such new patient, and the resulting body surface electrogram data and intracardiac EP mapping signals have been correlated to one another using machine learning; (8) updating or training the trained machine learning model at least partially using body surface electrogram data and intracardiac EP mapping signals obtained from a plurality of new patients determined to have atrial fibrillation prior to being treated by intra-cardiac ablation, where body surface electrogram data and intracardiac EP mapping signals are obtained from the plurality of new patients before and after atrial ablation procedures are performed in at least one atrium of each such new patient, and the resulting body surface electrogram data and intracardiac EP mapping signals have been correlated to one another using machine learning; (9) updating or training the trained machine learning model at least partially using body surface electrogram data and intracardiac EP mapping signals obtained from a plurality of new patients determined to have had atrial fibrillation previously, who were treated with a pulmonary vein isolation procedure previously, and who have been atrial-fibrillation-free for at least one year after being treated by the pulmonary vein isolation procedure, where body surface electrogram data and intracardiac EP mapping signals have been obtained from the plurality of new patients before and one year after the pulmonary vein isolation procedures, and the resulting body surface electrogram data and intracardiac EP mapping signals have been correlated to one another using machine learning; (10) updating or training the trained machine learning model at least partially using simulated body surface electrograms generated using a heart and torso model having one or more known origins of rotors or sources in one or more atria thereof; (11) updating or training the trained machine learning model at least partially using data from a plurality of patients, where the data from the patients relate to one or more of atrial volume, atrial dimensions, patient age, patient weight, patient height, and patient body mass index; (12) a trained machine learning model comprising one or more of: (a) a neural network, (b) a generative neural network; (c) a recurrent neural network, and (d) a feed-forward neural network; (13) a trained machine learning model comprising a recurrent neural network employing long short-term memory (LSTM); (14) a trained machine learning model comprising one or more of: (a) a nearest neighbor model; (b) a naive Bayes model; (c) a decision tree model; (d) a linear regression model; (e) a support vector machine (SVM) model, and (f) a neural network; (15) at least partially generating the trained machine learning model using supervised or unsupervised learning; (16) a trained machine learning model comprising convolutional layers; (17) removing or substantially removing at least portions of the QRS or QRST complex from at least some of the conditioned electrogram signals; (18) processing the EP mapping signals for at least some of the other patients using electrographic flow (EGF) methods to detect at least one of the presence of sources of atrial fibrillation in the other patients' hearts, the locations of sources of atrial fibrillation in the other patients' hearts, the activity levels of sources of atrial fibrillation in the other patients' hearts, the steadiness levels of sources of atrial fibrillation in the other patients' hearts, the flow angle stability levels of sources of atrial fibrillation in the other patients' hearts, and a classification of the other patients as A-type patients, B-type patients, or C-type patients, at least one of which sources, source locations, source activity levels. source steadiness levels, flow angle stability levels, and patient classifications have then been correlated with their corresponding body surface electrogram signals in the trained machine learning model; (19) employing Green's function in processing the EP mapping signals; and (20) EGF methods including at least one optical flow analysis technique selected from the group consisting of a Horn-Schunck method, a Buxton-Buston method, a Black-Jepson method, a phase correlation method, a block-based method, a discrete optimization method, a Lucas-Kanade method, and a differential method of estimating optical flow.
There are now described and disclosed various aspects, factors and details relating to a new metric we have developed called the “Electrographic Volatility Index” (or EVI). According to one embodiment, which is not intended to be limiting as to the number of parameters or mechanisms EVI may take into account in generating an EVI score or metric, or whether or not classification “types” of the kind disclosed and described herein (i.e., A, B, C, D and E types) are employed in generating EVI metrics or scores, and with reference to
A, B and C types are described in detail above. Types D and E are described in detail below. Note that such “types,” when employed to segregate data when generating EVI are merely derived from metrics such as activity. EVI is thus a formula that takes activity and other metrics into account, and from such metrics EVI directly computes something useful. It should therefore be understood that in some embodiments the use of “types” in how the generation of EVI scores and metrics are computed is merely a means of providing to users a simple-to-understand mechanism of how EVI operates, but also that the use of such “types” is not required or necessary to generate EVI scores or metrics.
The “Electrographic Volatility Index” or EVI is a metric or score that can be calculated, which, according to one embodiment that is not intended to be limiting, may be represented as:
EVI=(1−p(source activity))α·p(flow angle variability)β·(1−p(active fractionation))γ,
where the symbol “·” denotes convolution, and where α, β and γ are weighting or scaling numbers. In general, the concept of EVI is to create a statistical model that computes a score from the abovementioned (or additional) metrics. A statistical model can be this formula, which is parameterized by alpha, beta and gamma. These so-called hyper parameters can be tuned to achieve optimal significance of the statistical model. A neural network or any other machine learning model can beneficially be used to compute EVI scores. See, for example,
The EVI metric or score may be used to predict the probability of freedom from AF for a given patient, more about which is said below. In one embodiment, we mechanistically discriminate three different probabilities based on the three mechanisms described above: (i) source activity—sources that trigger the transition into AF; (ii) EGF flow variability (Flow Angle Variability or FAV) which breaks AF stability, and terminates AF; and (iii) Fractionation dependent flow origins, which represent independent triggers of so-called Active Fractionation (AFR) areas that are typically not detected as sources, but which exist in in sick atria.
There are multiple mechanisms that can be the cause of atrial fibrillation. While sources are one of them (e.g., A and B types), not all patient conditions can be explained by sources. According to one embodiment, the EVI aims at unifying multiple causes into a score ranging from 0% to 100% where 100% correlates strongly with freedom of AF as an outcome and 0% with recurrences.
As described in detail above, EGF mapping is a novel method of visualizing in vivo, near real-time cardiac action potential flow, providing actionable information for targeting and eliminating active sources that drive AF. Using EGF mapping algorithms, we can calculate the different probabilities of achieving freedom from AF based on the contributions of three distinct electrographically determined mechanisms of AF and combine them into an AF risk prediction score, called the EVI.
EVI goes beyond the identification of AF sources, and is capable of identifying the underlying mechanistic patterns of AF disease. During a procedure, a patient's future outcome is not pre-determined, but rather can be optimized by using real-time actionable information about mechanistic AF disease patterns to customize a targeted ablation strategy for an individual patient. Using electrographic flow (EGF) mapping algorithms, we can mechanistically discriminate three different probabilities based on the three distinct mechanisms described above.
To validate the ability of EVI to predict the likelihood of freedom from AF based on invasively measured electrophysiologic and substrate data from both atria, we analyzed a cohort of many patients that underwent FIRM mapping and ablation. We retrospectively derived the EVI on a corresponding development cohort of many patients who underwent FIRM-guided ablation and from whom a final 1-minute recording of unipolar electrograms from a 64-electrode basket catheter was obtained after the last ablation lesion. Those patients were then prospectively validated in a test cohort of many patients who underwent FIRM-guided ablation and had a final 1-minute recording of unipolar electrograms from a 64-electrode basket catheter after the last ablation lesion.
The demographics of the development and validation cohorts were similar. Using EGF mapping to quantify source activity (SAC), flow angle stability (FAV), and active fractionation (FRC), which each correspond to different AF mechanisms as described above, we found that by combining the different probabilities of freedom from AF 12 months post-ablation associated with each electrographic flow parameter for the patients in the development cohort, we could calculate the EVI, which strongly correlated with an individual patient's likelihood of freedom from AF at 12 months post-procedure (R2=0.998). We then prospectively applied the EVI to a corresponding validation cohort of many patients and found an equally strong correlation (R2=99.46).
Based on multi-electrode catheter recordings of unipolar electrograms analyzed using EGF mapping, a multivariate composite scoring system accounting for electrophysiologic properties of the atria as well as the underlying atrial substrate was derived retrospectively and applied prospectively. EVI predicted freedom from AF after ablation in both development and validation cohorts. EVI was discovered to provide a real-world picture of an individual patient's atrial fibrillatory status both prior to and after ablation.
In one embodiment, an EVI matrix may be configured as follows:
1. Leading Source Activity/p(Source)
p(source)=1−(Activity−BaseAct)/(1−BaseAct)
2. Flow Angle Variability/p(Variability)
p(variability)=FAV/FAVmax
3. Active Fractionation/p(Active_Fractionation)
p(active_fractionation)=1−Active Fractionation/FracMax
According to one example embodiment not intended to be limiting, a method for the computation of patient classification may be represented by pseudo-code as follows:
According to one example embodiment not intended to be limiting, a method for the computation of EVI may be represented by pseudo-code as follows:
Areas where the EGF is consistently going in the same direction over the course of a recording can be useful ablation targets. Flow angle variability measures the amount by which flow vectors change their direction at a given location. Low values correspond to stable flow, high values correspond to more chaotic, variable flow directions.
In one embodiment, for each (time-wise) subsequent pair of frames, we estimate a flow field. For each subsequent pair of flow fields, we compute the difference in degrees by which the vectors change their direction, typically taking the shortest angular distance. In one embodiment, therefore, one such flow angle variability map has the same dimensions as a single flow map, and has values between 0° and 180°.
In one embodiment, we now average all these flow angle variability maps over the entire recording, time-wise. The result is a map with the same dimensions as a single flow map, again with values between 0° and 180°, representing the average number of degrees that vectors at a given location change from frame to frame. Since in one embodiment the time delta between frames after subsampling is 19 ms, we report values for the mean flow angle variability in the following units: °/(19 ms). The metric shown in the right column in the recording view of
These metrics are computed after EGF estimation. If the EGF estimate is wrong, the resulting metrics will consequently be inaccurate. The main reason for inconsistent flow is bad electrode contact, which can be indicated to a user with an Electrode Score (see
It is known that complex fractionated atrial electrograms (CFAEs) may represent important sites for AF perpetuation: See, for example, Konings et al., “Configuration of unipolar atrial electrograms during electrically induced atrial fibrillation in humans,” Circulation 1997; 95:1231-41. Also, Kalifa et al. performed a computational study that showed that fractionation resulted from wave collisions from focal high frequency AF drivers in proximity to such fractionated potentials. See Kalifa et al., “Mechanisms of wave fractionation at boundaries of high frequency excitation in the posterior left atrium of the isolated sheep heart during atrial fibrillation,” Circulation 2006; 113:626-33. See also, for example, Sohal et al., “Is Mapping of Complex Fractionated Electrograms Obsolete,” Arrhythm. Electrophysiol. Rev. 2015 August; 4(2): 109-115; Atienza et al., “Mechanisms of Fractionated Electrograms Formation in the Posterior Left Atrium During Paroxysmal Atrial Fibrillation in Humans,” J Am Coll Cardiol. 2011 Mar. 1; 57(9): 1081-1092; and Correa de Sa et al., “Electrogram Fractionation—The Relationship between Spatiotemporal Variation of Tissue Excitation and Electrode Spatial Resolution,” Circ. Arrhythm. Electrophysiol. 2011 December; 4(6): 909-16. The foregoing Kalifa et al., Sohal et al., Atienza et al., and Correa de Sa et al. publications are hereby incorporated by reference herein, each in its respective entirety, such publications having been previously submitted in an IDS filed in conjunction with the '576 patent application.
It has been discovered that deriving the amount of fractionation in a signal from the ratio of the signal that is not attributed to flow conduction or far field is important. See the following mathematical descriptions. Here, and according to one non-limiting embodiment, we define fractionation as follows:
In one embodiment, the instantaneous component between signals picked up by two neighbouring electrodes is computed as correlation between those signals:
E
instantaneous(s1,s2)=Σt=1#sampless1[t]s2[t]
In one embodiment, the instantaneous component of an electrode is an average of Einstantaneous between the signals picked up by the electrode and its neighbours respectively.
In one embodiment, the conduction component between two signals is determined by the biggest peak in cross-correlation between these two signals (see
In one embodiment, the conduction component is undefined if:
E
conduction
=E
signal(s1)Econduction(s1,s2),
where s2 are neighbors of s1 such that Econduction(s1, s2) is defined as shown above.
Referring to the example of
In some patients' atria, it is believed that there exist areas with a high degree of fractionation which emanate action potentials. These might not be detected as sources due to the inherently asymmetrical nature of such sources of action potential flow. The active fractionation (AFR) metric aims at quantifying the amount of action potential flow originating from areas of high fractionation. This metric may be computed from two components: fractionation (described above) and streamline origin density (SOD). The SOD is derived by tracing back the flow field until convergence to identify origins of EGF.
For each flow field (e.g., 29 in a 60 second recording), we follow all arrows against their directions. When this tracing converges, we record this as a streamline origin point. Finally, we report the average fractionation value at the location of these streamline origins. If the streamline origins are mostly at sources without fractionation, this value will be close to 0. In the other case, the result will be up to 100%. Generally, the AFR metric is not used for ablation guidance at this point. The fractionation amount can always be verified in the ECG view. In addition, to analyze the flow of action potentials in the atria, it is preferred to separate atrial action potentials (or p waves) from the QRS complex far field.
Referring now to
In
In
1. EGF-Identified AF Source Activity (Act): Active Sources Trigger the Transition into AF
Leading Source Activity/p(Source):
p(source)=1−(Activity−BaseAct)/(1−BaseAct)
2. EGF Variability (Flow Angle Variability, FAV): Destabilizes and Terminates AF
Flow Angle Variability/p(Variability):
p(variability)=FAV/FAVmax
3. Active Fractionation (AFR); Action Potential Flow in Areas of High Fractionation
Active Fractionation/p(Active_Fractionation):
Referring now to
Using the EGF and EVI techniques described above, an arrhythmia mapping system can be provided that provides in-vivo, real-time visualization of cardiac action potential flow (EGF Mapping), and that is capable of providing actionable information that a physician can use to target and eliminate active AF sources that matter. Diagnostic and prognostic mapping tools can be provided that generate real-time panoramic electrographic data and analytics specific to individual patients, and that are actionable during a patient's procedure. This minimizes empirical and/or unnecessary ablations, thereby reducing potential complications, improving individual patients' outcomes post-ablation, and providing a quantitative and reasonably accurate “picture” of patients' responses to ablation therapy. In addition, the EGF and EVI techniques described and disclosed herein can be used to provide a “picture” of an individual's baseline or chronic disease state, and iterative “pictures” of disease after each intervention in step-wise fashion for longitudinal management of the chronic disease. Data aggregation can be leveraged over time to assess and even compare previous strategies to provide tailored and timely recommendations to inform treatment strategy. Pharmaceutical therapy data for individual patients can also be added to the statistical analyses that are carried out. Speed and efficacy can be improved, costs of procedures can be reduced, and expert decision-making intelligence can be employed to inform complex ablation strategies. EGF and EVI, used in combination, can hamess the power of longitudinally-collected, and unifying/comparative real-world procedural, data across operators, hospitals, centers, ablation techniques, energy modalities and lesion sets into a single cloud-based database, which may then be employed to inform clinical decision-making, patient management, and population-based research.
It will now also be seen that EVI can be employed to predict the probability of freedom from AF after a catheter ablation procedure has been carried out. Currently, patients with a variety of clinical presentations undergo a wide range of ablation procedures with varying ablation techniques, ablation energy sources, and combinations of lesion sets. Using electrographic flow (EGF) mapping algorithms, we can mechanistically discriminate three different probabilities based on three mechanisms (1) source activity as sources trigger the transition into AF; (2) EGF flow variability or flow angle variability, which reduces AF stability and terminates AF; and (3) fractionation-dependent flow origins, which represent independent triggers not detected as sources, but influencing the nature of action potential flow in the atria. As shown above, we have validated the ability to predict the likelihood of freedom from AF using a clinical scoring system, where EP mapping data were collected using unipolar basket catheter electrodes. Based on multielectrode catheter recordings of unipolar electrograms analyzed using EGF mapping, a multivariate composite scoring system accounting for electrophysiologic properties of the atria as well as the underlying atrial substrate was derived retrospectively and applied prospectively. EVI predicted freedom from AF after ablation in both a development cohort and a validation cohort of patients undergoing ablation for AF. EVI is shown to provide a real-world picture of an individual patient's atrial fibrillatory status both prior to and after ablation.
In some embodiments, there are provided systems configured to generate an estimate or probability of a patient being free from atrial fibrillation (AF), the systems comprising at least one computing device comprising at least one non-transitory computer readable medium configured to store instructions executable by at least one processor to determine the source and location of the atrial fibrillation in the patient's heart, the computing device being operably connected to a display or monitor, the computing device being configured to: (a) receive electrogram signals from one or more of intracardiac electrodes, body surface electrodes, ECG monitoring leads, and cardiac monitoring patches; (b) assign positions of the electrodes on a mapping electrode assembly employed to acquire the electrogram signals to their corresponding electrogram signals; (c) provide or generate a map, representation, or data set of the electrode positions; (d) process the electrogram signals to generate a plurality of electrogram surfaces corresponding at least partially to the map, representation, or data set; (e) process the plurality of electrogram surfaces through time to generate at least one electrographical flow (EGF) map, representation, pattern, or data set; (f) process the at least one EGF map, representation, pattern, or data set to determine at least two of source activity levels, flow angle variability (FAV) levels, and active fractionation (AFR) levels corresponding thereto; (g) determine and generate, on the basis of a combination of the determined at least two of source activity levels, FAV levels, and AFR levels, an electrographical volatility index (EVI) representative of the estimate or probability of the patient being free from AF, wherein at least one of the EVI and the estimate or probability of the patient being free from AF is presented on a display, monitor, or printer to a user.
In some embodiments, the foregoing systems can further comprise any one or more of: (a) the computing device being configured to convolve at least two of the determined source activity levels, the determined flow angle variability levels, and the determined active fractionation levels with one another to provide the estimate or probability of the patient being free from AF; (b) the determined source activity levels corresponding to at least one of Type A atrial behavior exhibiting stable rotors and drivers and Type B atrial behavior where rotors switch on and off; (c) the determined flow angle variability levels corresponding to Type D atrial behavior exhibiting stable reentry patterns with low FAV; (d) the determined active fractionation levels corresponding to Type E atrial behavior exhibiting a combination of active fractionation and action potential flow origins; (e) the activity level corresponding to a percentage of time a detected source is determined to be on or active; (f) when the percentage of time the detected source is on or active is greater than about 25% the activity level is deemed to be high, and the probability the patient is free from AF is lower; (f) when the percentage of time the detected source is on or active is greater than between about 26% and about 30% the activity level is deemed to be high; (g) when the percentage of time the detected source is on or active is less than about 30% the activity level is deemed to be low, and the probability the patient is free from AF is deemed to be higher; (h) when the percentage of time the detected source is on or active is less than between about 26% and about 30% the activity level is deemed to be low, and the probability the patient is free from AF is deemed to be higher; (i) the flow angle variability level corresponding to one or more EGF flow angles computed over a predetermined period of time; (j) a flow angle level exceeding a range between about 4 and 5 degrees measured over about 20 milliseconds is deemed to be high, and the probability the patient is free from AF is deemed to be higher; (k) a flow angle level less than a range between about 4 and 5 degrees measured over about 20 milliseconds is deemed to be low, and the probability the patient is free from AF is deemed to be lower; (l) the active fractionation level corresponds to a combination of measuring divergence in EGF flow patterns indicative of action potential origins and measuring a percentage of a surface area of the patient's atrium determined to be fractionated on the basis of divergent EGF flow patterns; (l) when the active fractionation level exceeds a level between about 27 percent and about 31 percent of a surface area of an analyzed portion of the patient's atrium exhibiting divergence in EGF flow patterns over a predetermined period of time, the probability the patient is free from AF is lower; (m) when the active fractionation level falls below a level between about 27 percent and about 31 percent of a surface area of an analyzed portion of the patient's atrium exhibiting divergence in EGF flow patterns over a predetermined period of time, the probability the patient is free from AF is higher; (n) the EVI is generated in accordance with the formula: EVI=(1−p(source activity))α·p(flow angle variability)β·(1−p(active fractionation))γ, where the symbol “·” denotes convolution.
In further embodiments, there are provided methods of generating an estimate or probability of a patient being free from atrial fibrillation (AF), the method employing at least one computing device comprising at least one non-transitory computer readable medium configured to store instructions executable by at least one processor to determine the source and location of the atrial fibrillation in the patient's heart, the computing device being operably connected to a display or monitor, the methods comprising: (a) receiving electrogram signals acquired from electrodes located inside the patient's heart; (b) using the computing device, assigning positions of the electrodes on a mapping electrode assembly employed to acquire the electrogram signals to their corresponding electrogram signals; (c) using the computing device, providing or generating a map, representation, or data set of the electrode positions; (d) using the computing device, processing the electrogram signals to generate a plurality of electrogram surfaces corresponding at least partially to the map, representation, or data set; (e) using the computing device, processing the plurality of electrogram surfaces through time to generate at least one electrographical flow (EGF) map, representation, pattern, or data set; (f) using the computing device, processing the at least one EGF map, representation, pattern, or data set to determine at least two of source activity levels, flow angle variability (FAV) levels, and active fractionation (AFR) levels corresponding thereto; (g) using the computing device, determining and generating, on the basis of a combination of the determined at least two of source activity levels, FAV levels, and AFR levels, an electrographical volatility index (EVI) representative of the estimate or probability of the patient being free from AF, and (h) presenting at least one of the EVI and the estimate or probability of the patient being free from AF on a display, monitor, or printer to a user.
In some embodiments, such foregoing methods can further comprise any one or more of: (a) the computing device convolving at least two of the determined source activity levels, the determined flow angle variability levels, and the determined active fractionation levels with one another to provide the estimate or probability of the patient being free from AF; (b) the determined source activity levels corresponding to at least one of Type A atrial behavior exhibiting stable rotors and drivers and Type B atrial behavior where rotors switch on and off; (c) the determined flow angle variability levels corresponding to Type D atrial behavior exhibiting stable reentry patterns with low FAV; (d) the determined active fractionation levels corresponding to Type E atrial behavior exhibiting a combination of active fractionation and action potential flow origins; (e) the activity level corresponding to a percentage of time a detected source is determined to be on or active; (f) when the percentage of time the detected source is on or active is greater than about 25% the activity level is deemed to be high, and the probability the patient is free from AF is lower; (g) when the percentage of time the detected source is on or active is greater than between about 26% and about 30% the activity level is deemed to be high; (h) when the percentage of time the detected source is on or active is less than about 30% the activity level is deemed to be low, and the probability the patient is free from AF is deemed to be higher; (i) when the percentage of time the detected source is on or active is less than between about 26% and about 30% the activity level is deemed to be low, and the probability the patient is free from AF is deemed to be higher; (j) the flow angle variability level corresponds to one or more EGF flow angles computed over a predetermined period of time; (k) a flow angle level exceeding a range between about 4 and 5 degrees measured over about 20 milliseconds is deemed to be high, and the probability the patient is free from AF is deemed to be higher; (l) a flow angle level less than a range between about 4 and 5 degrees measured over about 20 milliseconds is deemed to be low, and the probability the patient is free from AF is deemed to be lower; (m) the active fractionation level corresponds to a combination of measuring divergence in EGF flow patterns indicative of action potential origins and measuring a percentage of a surface area of the patient's atrium determined to be fractionated on the basis of divergent EGF flow patterns; (n) when the active fractionation level exceeds a level between about 27 percent and about 31 percent of a surface area of an analyzed portion of the patient's atrium exhibiting divergence in EGF flow patterns over a predetermined period of time, the probability the patient is free from AF is lower; (o) when the active fractionation level falls below a level between about 27 percent and about 31 percent of a surface area of an analyzed portion of the patient's atrium exhibiting divergence in EGF flow patterns over a predetermined period of time, the probability the patient is free from AF is higher; and (p) generating the EVI is determined in accordance with the formula: EVI=(1−p(source activity))+·p(flow angle variability)β·(1−p(active fractionation))γ, where the symbol “·” denotes convolution.
Referring now to
Continuing to refer to
Problems with the current AF treatment paradigm include AF core drivers or functional AF mechanisms being inadequately understood, procedural complexity and cost, and data siloes and a resulting inefficient patient journey. We now examine each of these problems in further detail.
AF Core Drivers and Mechanisms are Inadequately Understood
Catheter ablation success rates for persistent AF are low (˜50-60%). Outdated clinical classification causes heterogenous disease to be treated as a single phenotype, and a lack of understanding of underlying AF pathophysiology increases the risk of harmful over-ablation.
At the present time, AF mechanisms are not fully understood. How AF is perpetuated is still debated. Proposed AF mechanisms include multiple propagated wavelets, localized focal sources, and reentrant activity with fibrillatory conduction. See Calkins H et al, Heart Rhythm 2017; 14(10); 275-444.
Better understanding of an individual patient's underlying AF mechanisms is needed to improve patient management and optimize ablation outcomes by tailoring therapeutic strategies to an individual patient's pathophysiology. A serious and rather common consequences of inadequate understanding of core AF drivers includes ablation outcomes being inadequate. Ablation success rates have been shown to be ˜46-59% for patients with persistent AF; see Verma A et al, N Engl J Med 2015; 372:1812-22.
Pulmonary vein isolation (PVI) remains a cornerstone of AF ablation. See Calkins H et al, Europace 2012; 14:528-606. ⅔rds of surveyed EU centers perform PVI alone as a first-line therapy for persistent AF. See Dagres N et al, Europace 2015; 17:1596-1600. Although PVI alone has a higher success rate (59%) than ablation, there seems to be a ceiling of success.
Adjunctive ablation strategies have been explored, but no consensus or standard has been achieved.
Outdated clinical classifications for AF are widely employed. AF is a heterogenous disease typically treated as a single phenotype. Abnormalities arise, however, from diverse pathophysiological mechanisms. Indeed, AF represents a final common phenotype for multiple disease pathways and mechanisms that are incompletely understood. See January C T et al, Circulation 2014; 130:2071-2104.
Patients classified in identical clinical categories may be inherently heterogenous in terms of AF temporal persistence. See Charitos E et al, J Am Coll Cardiol. 2014; 63:2840-8.
The risk of over-ablation in an AF procedure can be quite significant. An inadequate understanding of core drivers creates a bias toward over-ablation. The extent of ablation has increased over time in an effort to eliminate diseased atrial substrates associated with the origin and persistence of AF. See Masuda M et al, PACE 2012; 35; 327-34. Extensive ablation can result in atrial injury and scarring, and can increase iatrogenic proarrhythmic effects. Moreover, increases in procedure time and complexity have been shown not to improve freedom from AF. See Sau A et al Europace 2019; 21:1176-84.
AF ablation procedures are long and complex, which limits the number of centers capable of performing the procedure. Catheter ablation for AF can take on average 2-4 hours (and up to 6 hours), depending on the complexity of the procedure and ablation technique.
Except as outlined above, AF ablation procedural metrics do not exist, providing no method for confirming procedural success or assessing impact. There is also no method for confirming successful elimination of AF sources. Intra-procedural and inter-procedural quantitative assessment of atrial health, propensity to AF, AF complexity, etc., simply do not exist in the prior art. Based on meta-analysis of 58 studies, intraprocedural AF terminations had no significant impact on freedom from AF. See Sau A et al, Europace 2019; 21:1176-84.
In addition, AF ablation tools and equipment are costly. PVI is considered the cornerstone of catheter ablation and represents the simplest, fastest version of AF ablation. Integration of adjunctive ablation increases procedural complexity and time, and also requires increased operator skill and experience.
AF ablation requires 3D electroanatomic navigation systems, multi-electrode mapping catheters, ablation catheters, intracardiac echocardiography, sheaths, and transseptal needles. Reimbursement for such procedures is generally fixed. Physicians have a wide range of choices available to them when it comes to performing AF ablation, and their selection of tools determines the cost of the procedure. See Winkle et al, J Interv Card Eletrophysiol 2013; 36:157-65.
One consequence of procedural complexity and high cost is that ablation, the only potentially curative therapy for AF, is largely restricted to highly trained Tier I users due to a high skill set barrier to entry. There therefore exists a high market demand for solutions that simplify and shorten ablation procedures.
Data siloes and an inefficient patient journey present formidable obstacles to efficacious and efficient AF treatment. A lack of inter-procedural continuity prevents direct comparisons of available data (e.g., electroanatomic maps and ablation lesions). Large AF clinical research networks do not exist, creating additional clinical and research inefficiencies. Noninvasive assessments of AF disease and complexity do not currently exist. Consequently, an inherent lack of information exists concerning AF, particularly as regards individual patients' AF disease states. There is no centralized dataset of mapping tied to patient outcomes, which is necessary to create a better understanding of AF driving mechanisms. Data is siloed and fragmented, causing clinical inertia and research inefficiencies.
An NHLBI White Paper published in February, 2020 (Al-Khatib S M et al, Circulation 2020; 141:482-92) outlined 3 key research priorities:
Continuity between AF procedures generally does not exist. Persistent AF patients require on average 2.1±1.1 ablation procedures over 5 years to achieve 55.9% freedom from recurrence. See Schreiber D et al, Circ Arrythm Electrophysiol 2015; 8(2):308-17. Signal and mapping data are often stored on local hard drives, making it difficult to retrieve relevant data between procedures. Direct comparisons of electroanatomic maps and ablation lesions between procedures is generally not possible, and longitudinal comparisons of inter-procedural AF metrics are non-existent.
Noninvasive assessment of the need for PVI+ also does not exist currently. There is no way to know whether a patient will require more than just PVI prior to general anesthesia and advancing sheaths and catheters into the heart. Moreover, it is difficult to noninvasively phenotype AF in a way that reflects clinical endpoints. See Rodrigo M et al, Circ Arrythm Electrophysiol 2020; 13(3):e007700.
Persistent AF ablation cases are fraught with unknowns in terms of ablation strategy planning, creating procedural scheduling inefficiencies, cost inefficiency due to uninformed tool selection, and unmet patient expectations.
Some of the consequences of data siloes and the inefficient patient journey include the lack of longitudinal patient data preventing efficacious long-term AF disease management, inefficiencies in the current paradigm adding unnecessary cost and complexity to the system, the lack of real-world outcome data being tied to particular ablation strategies prevents comparative effectiveness analyses and the development of refined predictive capabilities.
Referring now to
Step 2 (508): Current classification based on temporal persistence: paroxysmal or persistent?
Step 3 (510): Personalized diagnostics (single-lead biomarker added to conventional monitoring patch analysis): Presence of time-dependent patterns correlated with AF complexity or not? Example: Use wearable or in-office body surface electrodes to acquire body surface electrograms.
Step 4 (510): More personalized diagnostics (multi-patch v. multi-lead patch biomarker): Predicts likely complexity of patient's AF disease. Example: ≥2 simultaneous cardiac monitoring patches or a multi-lead cardiac monitoring patch (“ML patch”) with 2-8 leads.
Step 5 (510): Personalized risk stratification (e.g., 64-electrode body surface mapping): Estimates noninvasive EVI for individual AF risk stratification and strategic pre-operative planning. Use cardiac monitoring patches with EGF-powered analytics provided if enough analyzable AF is recorded.
Step 6 (506): Precision intervention (e.g., AblaMap®: biatrial 64-electrode intracardiac mapping): Provides real-time diagnostic, prognostic, and therapeutic guidance and dynamic calculated EVI Step 7 (506): Longitudinal patient monitoring (steps 2-6): Cloud-based database of bioinformatics that can be used iteratively to benchmark disease status and response to treatments.
In accordance with the foregoing problems concerning AF diagnosis and treatment, we have developed a comprehensive arrhythmia management solution that enhances the current level of understanding of cardiac arrhythmias and creates a new paradigm in the treatment of AF. Ablamap, which employs the EGF techniques and systems described above, offers a truly differentiated mapping technology, and is the only technology that provides real-time or near-real-time visualization of cardiac action potential flows (electrographic flow or EGF). Distinct AF phenotypes have been observed using EGF techniques and systems, enabling real-time or near-real-time optimization and customization of ablation strategy. EGF and EVI techniques and systems described herein have been discovered to provide valuable insights into a patient's AF state.
AblaMap®: The first and only platform that detects and displays functional AF mechanisms via electrographic flow (EGF) in real time or near-real time.
Electrographic Volatility Index (EVI): A unified metric for assessing the expected likelihood of (e.g.) 12-month freedom from AF calculated pre- and post-ablation, derived from real-time electrophysiologic parameters as described above.
AblaCath®: A state-of-the-art global basket catheter configured to provide high fidelity electrograms to the AblaMap system.
AblaSurface®: A non-invasive body surface diagnostic technology configured to provide EVI estimates and to stratify or classify patients for appropriate intervention.
AblaCloud®: A platform configured for the aggregation of longitudinal patient data and analytics to facilitate long-term AF disease management.
AblaMap is the first and only platform that detects and displays action potential flows of EGF, which enables the visualization of distinct and dynamic functional AF mechanisms in real time or near-real time during the mapping/ablation procedure. As a result, EGF is redefining AF phenotypes based on the presence or absence of functional AF mechanisms. This, in turn, optimizes diagnostic and other procedures from the start, minimizes unnecessary and/or empiric ablations, decreases the risk of over-ablation and its ensuing complications, democratizes expert intelligence and knowledge, and enables less skilled physicians to perform more complex and more efficacious ablations.
Type 0=no functional AF mechanisms;
Type 1=1 functional AF mechanism;
Type 2=2 functional AF mechanisms
Type 3=source-activity dependent AF
The detection and visualization of such functional AF mechanisms facilitates personalization and customization of interventional ablation strategies to individual patients based on their underlying AF pathophysiology. We have discovered that these mechanistically-based phenotypes correlate with clinical outcomes and can be used to predict ablation treatment response.
Step 1: Patient is symptomatic or wearables (e.g., body surface electrodes in a vest, other type of clothing or patch, ECG lead, patch, watch or other wearable device or system) detect potential arrhythmias and direct patient to see a doctor. The system recognizes that there may be a problem.
Step 2: Physician orders a cardiac monitor (e.g., body surface electrode patch) to diagnose AF. Following diagnosis, the patient may be an ablation candidate. The system tells “what” is wrong but not “why.”
Step 3: EP performs non-invasive body surface mapping to obtain personalized diagnostic and prognostic information. This permits individual risk stratification.
Step 4: EPs assess lesions and direct treatment decisions based on EGF and EVI technology. The system tells “why” and the best way to treat the patient.
Step 5: Traditional medtech strategics offer varying suites of ablation technologies to treat AF (treatment).
Step 6: EVI recalculated post-ablation to determine outcome, prognosis and to permit a monitoring and/or treatment plan to be formulated. The system provides an endpoint and prognosis.
Step 7: Longitudinal, iterative AF disease monitoring with estimated EVI for progression and response to treatment. The system reveals how healthy a patient's atria are.
Step 8: Short- and medium-term post-procedure cardiac monitoring. The system reveals whether the patient is free from AF.
Step 9: Long-term monitoring with wearables (e.g., body surface electrodes in a vest, other type of clothing or patch, ECG lead, patch, watch or other wearable device or system) to track outcomes and facilitate re-entry into a treatment continuum if AF returns. The system continues to reveal whether the patient remains free from AF.
Thus, an end-to-end AF data ecosystem that follows the patient can be provided using the tools and techniques described and disclosed herein. This end-to-end data ecosystem can be configured to own and capture data from every or selected clinical interactions—from diagnosis, through treatment, to post-procedure monitoring, and outcomes. Pre- and post-procedure data can be linked with best-in-class intra-procedural data, enabling a complete, unparalleled data continuum to exist for the AF patient. We have discovered that integrating EVI techniques, methods, systems and devices into body surface electrode data processing systems and algorithms meaningfully increases diagnostic and/or prognostic power, introducing a measurable and significant advantage over existing conventional cardiac patch monitoring technologies.
A comprehensive non-invasive body surface mapping solution that provides biomarkers of AF disease complexity based on validated EGF parameters and EVI offers a first and best-in-class non-invasive biosignaling technology for personalized, precision AF medicine. Personalized risk stratification based on non-invasively derived electrographic volatility index (EVI) informs pre-operative planning. Powered by advanced neural networking as described herein, the more data input, the better the predictive power of the system becomes. Thus, this solution and system targets a clear unmet need. Inter-procedural quantitative assessments of atrial health and complexity of AF disease, i.e., AF “biomarkers” do not exist in the prior art. There is no way to know whether an individual patient will require more than a PVI prior to advancing sheaths and catheters into the heart. It is also difficult using existing techniques and methods to non-invasively phenotype AF with correlations to procedural endpoints and clinical outcomes.
These problems are solved using the body surface electrode-based system and techniques described herein, which provide first- and best-in-class non-invasive metrics for assessing AF disease, providing risk stratification, and predicting prognosis using a cloud-based data analytics platform. As more and more data is uploaded to the cloud-based data analytics platform, the better the prognostications and diagnoses the system can provide as the system shown in
The comprehensive non-invasive body surface mapping solution described and disclosed herein provides biomarkers of AF disease complexity based on validated EGF parameters and EVI. As described above, the system is configured to utilize one or more patches, leads or wearables fitted with unipolar or bipolar electrodes or sets of electrodes that are configured to acquire cardiac signals from the body surface of a patient. In some embodiments, the one or more patches, leads or wearables are configured for placement over or near a patient's heart, either on or both of the front and rear of the patient's torso, or over or near the patient's heart. Other locations for patches, leads or wearables are also contemplated. Each patch, lead or wearable can include 1, 2, 3, 4, or up to 256 or even more unipolar or bipolar electrodes or sets of electrodes
The patches, leads, or wearables are configured to acquire and/or store data corresponding to the patient's cardiac signals, and to relay the acquired and/or stored data to an external computing device for further EGF data processing and analysis using, for example, known medical data telemetry communication protocols and methods, hard-wiring, Bluetooth, WiFi, and/or any other suitable wired or wireless communication methods.
Some non-limiting examples of conventional cardiac monitoring patch technology that may be modified and/or adapted for use in accordance with the various inventions described and disclosed herein include the systems, devices, components, and methods disclosed in the following U.S. Pat. Nos. 8,150,502; 8,160,682; 8,244,335; 8,538,503; 8,560,046; 9,173,670; 9,241,649; 9,451,975; 9,597,004; 9,955,887; 10,098,559; 10,271,754; 10,299,691; D852965; D854167; 10,405,799; 10,517,500, all of which are hereby incorporated by reference herein, each in its respective entirety. Those skilled in the art will realize that certain aspects and features disclosed and described in in the foregoing patents can be employed in, or adapted and modified for use in, the systems, devices, components, and methods described and disclosed herein.
Some examples of Electrographic Flow (EGF), EVI, patient classification, machine learning, body surface electrode, and other technologies that may be modified and/or adapted for use in accordance with the various inventions described and disclosed herein include, but are not limited to, the systems, devices, components, and methods disclosed in the following U.S. patents and patent applications: U.S. Pat. No. 10,201,277 to Ruppersberg; U.S. Pat. No. 10,143,374 to Ruppersberg; U.S. patent application Ser. No. 16/387,873 to Ruppersberg; U.S. patent application Ser. No. 15/923,286 to Ruppersberg; U.S. Provisional Patent Application Ser. No. 62/659,513 to Ruppersberg; U.S. Provisional Patent Application Ser. No. 62/784,605 to Ruppersberg et al.: U.S. patent application Ser. No. 16/724,254 to Ruppersberg et al.; U.S. Provisional Patent Application Ser. No. 62/875,452 to Ruppersberg et al.; U.S. patent application Ser. No. 16/931,844 to Ruppersberg et al.; and U.S. Provisional Patent Application Ser. No. 63/032,238 to Ruppersberg et al., all of which are hereby incorporated by reference herein, each in its respective entirety. Those skilled in the art will also realize that certain aspects and features disclosed and described in the foregoing patents can be employed in, or adapted and modified for use in, the systems, devices, components, and methods described and disclosed herein.
Machine learning (ML) risk predictions associated with EGF parameters and EVI will continuously improve as more and more data is added to the system and are anticipated to likely outperform existing clinical risk scores.
Note that the body surface electrode-based methods and systems described above can be adapted and configured to include intracardiac data. In one embodiment, such intracardiac data can be acquired simultaneously with the body surface electrode-based data. Intra-cardiac and body surface data can then be combined during data processing to provide enhanced EGF estimates and EVI predictions.
Further embodiments will become apparent to those skilled in the art after having read and understood the claims, specification and drawings hereof.
The various systems, devices, components and methods described and disclosed herein may also be adapted and configured for use in electrophysiological mapping applications other than those involving the interior of a patient's heart. These alternative applications include EP mapping and diagnosis of a patient's epicardium, nerves, including nerves in the renal arteries, a patient's spinal cord or other nerves, or a patient's brain or portions thereof.
It will now be seen that the various systems, devices, components and methods disclosed and described herein are capable of detecting with considerable accuracy and precision the locations and types of sources of cardiac rhythm disorders in a patient's heart, diagnosing same, and making better informed and more accurate and likely-to-succeed treatment decisions for patients.
In view of the structural and functional descriptions provided herein, those skilled in the art will appreciate that portions of the described devices and methods may be configured as methods, data processing systems, or computer methods. Accordingly, these portions of the devices and methods described herein may take the form of a hardware embodiment, a software embodiment, or an embodiment combining software and hardware, such as shown and described with respect to computer system 300 illustrated in
Certain embodiments of portions of the devices and methods described herein are also described with reference to block diagrams of methods, systems, and computer methods. It will be understood that such block diagrams, and combinations of blocks diagrams in the Figures, can be implemented using computer-executable instructions. These computer-executable instructions may be provided to one or more processors of a general purpose computer, a special purpose computer, or any other suitable programmable data processing apparatus (or a combination of devices and circuits) to produce a machine, such that the instructions, which executed via the processor(s), implement the functions specified in the block or blocks of the block diagrams.
These computer-executable instructions may also be stored in a computer-readable memory that can direct computer 300 or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory result in an article of manufacture including instructions which implement the function specified in an individual block, plurality of blocks, or block diagram. The computer program instructions may also be loaded onto computer 300 or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on computer 300 or other programmable apparatus provide steps for implementing the functions specified in the an individual block, plurality of blocks, or block diagram.
In this regard,
It will now be seen that the various systems, devices, components and methods disclosed and described herein are capable of detecting with considerable accuracy and precision the locations of sources of cardiac rhythm disorders in a patient's heart.
What have been described above are examples and embodiments of the devices and methods described and disclosed herein. It is, of course, not possible to describe every conceivable combination of components or methodologies for purposes of describing the invention, but one of ordinary skill in the art will recognize that many further combinations and permutations of the devices and methods described and disclosed herein are possible. Accordingly, the devices and methods described and disclosed herein are intended to embrace all such alterations, modifications and variations that fall within the scope of the appended claims. In the claims, unless otherwise indicated, the article “a” is to refer to “one or more than one.”
The foregoing outlines features of several embodiments so that those skilled in the art may better understand the detailed description set forth herein. Those skilled in the art will now understand that many different permutations, combinations and variations of the systems, devices, components and methods described and disclosed herein fall within the scope of the various embodiments. Those skilled in the art should appreciate that they may readily use the present disclosure as a basis for designing or modifying other processes and structures for carrying out the same purposes and/or achieving the same advantages of the embodiments introduced herein. Those skilled in the art should also realize that such equivalent constructions do not depart from the spirit and scope of the present disclosure, and that they may make various changes, substitutions and alterations herein without departing from the spirit and scope of the present disclosure.
After having read and understood the present specification, those skilled in the art will now understand and appreciate that the various embodiments described herein provide solutions to long-standing problems, both in the use of electrophysiological mapping systems and in the use of cardiac ablation systems.
| Number | Date | Country | Kind |
|---|---|---|---|
| PCT/EP2015/001801 | Sep 2015 | EP | regional |
| PCT/EP2015/001803 | Sep 2015 | EP | regional |
This application is related to, and claims priority and other benefits from: (a) U.S. Provisional Patent Application Ser. No. 63/092,485 entitled “Systems, Devices, Components and Methods for Classifying, or Detecting the Locations of Sources of, Cardiac Rhythm Disorders in a Patient's Heart Using Body Surface Electrodes and/or Cardiac Monitoring Patches” to Ruppersberg et al. filed Oct. 15, 2020 (hereafter “the '485 patent application”);(b) U.S. Provisional Patent Application Ser. No. 63/196,605 entitled “Methods, Systems, Devices, and Components for Extracting Atrial Signals from QRS and QRST Complexes” to Tenbrink et al. filed Jun. 3, 2021 (hereafter “the '605 patent application”);(c) U.S. Provisional Patent Application Ser. No. 63/221,291 entitled “Biosignal-Based Intracardiac Navigation Systems, Devices, Components and Methods” to Denner et al. filed Jul. 13, 2021 (hereafter “the '291 patent application”), and(d) U.S. Provisional Patent Application Ser. No. 63/222,346 entitled “Biosignal-Based Intracardiac Navigation Systems, Devices, Components and Methods” to Denner et al. filed Jul. 15, 2021 (hereafter “the '346 patent application”). This application is also a continuation-in-part of, and claims priority and other benefits from: (e) U.S. patent application Ser. No. 16/387,873 to Ruppersberg filed on Apr. 18, 2019, which is entitled “Systems, Devices, Components and Methods for Detecting the Locations of Sources of Cardiac Rhythm Disorders in a Patient's Heart and Classifying Same” (hereafter “the '873 patent application”);(f) U.S. patent application Ser. No. 16/724,254 to Haeusser et al. filed on Dec. 21, 2019, which is entitled “Systems, Devices, Components and Methods for Detecting the Locations of Sources of Cardiac Rhythm Disorders in a Patient's Heart” (hereafter “the '254 patent application”);(g) U.S. patent application Ser. No. 17/212,789 to Ruppersberg et al. filed on Mar. 25, 2021, which is entitled “Systems, Devices, Components and Methods for Detecting the Locations of Sources of Cardiac Rhythm Disorders in a Patient's Heart” (hereafter “the '789 patent application”), and(h) U.S. patent application Ser. No. 17/331,576 to Ruppersberg et al. filed on May 26, 2021, which is entitled “Systems, Devices, Components and Methods for Detecting the Locations of Sources of Cardiac Rhythm Disorders in a Patient's Heart and Generating an Estimate or Probability of the Patient Being Free from Atrial Fibrillation” (hereafter “the '576 patent application”). The '873 patent application is a continuation-in-part of: (a) U.S. patent application Ser. No. 16/231,883 entitled “Systems, Devices, Components and Methods for Detecting the Locations of Sources of Cardiac Rhythm Disorders in a Patient's Heart” to Ruppersberg filed Dec. 24, 2018 (hereafter “the '883 patent application”), now U.S. Pat. No. 10,980,418; (b) U.S. patent application Ser. No. 16/168,235 entitled “Systems, Devices, Components and Methods for Detecting the Locations of Sources of Cardiac Rhythm Disorders in a Patient's Heart” to Ruppersberg filed Oct. 23, 2018 (hereafter “the '235 patent application”), now U.S. Pat. No. 10,806,343, and (c) U.S. patent application Ser. No. 15/293,286 entitled “Systems, Devices, Components and Methods for Detecting the Locations of Sources of Cardiac Rhythm Disorders in a Patient's Heart” to Ruppersberg filed Oct. 14, 2016 (hereafter “the '286 patent application”), now U.S. Pat. No. 10,820,800. The '254 patent application claims the benefit of U.S. Provisional Patent Application 62/784,605 filed Dec. 24, 2018 (hereafter “the '605 patent application”), and U.S. Provisional Patent Application 62/875,452 filed December Jul. 17, 2019 (hereafter “the '452 patent application”). The '254 patent application also a continuation-in-part of: (a) the '235 patent application, and (b) the '286 patent application. The '789 patent application is a continuation of the '883 patent application. The '883 patent application is a continuation of U.S. patent application Ser. No. 15/548,671 entitled “Systems, Devices, Components and Methods for Detecting the Locations of Sources of Cardiac Rhythm Disorders in a Patient's Heart” to Ruppersberg filed Aug. 3, 2017 (hereafter “the '671 patent application”), now U.S. Pat. No. 10,201,277. The '671 patent application is a 371 of International Patent Application PCT/IB2016/001273 to Ruppersberg filed Sep. 7, 2016 (hereafter “the '001273 patent application”). The '789, '883, and '671 patent applications all claim priority and other benefits from: (a) International Patent Application PCT/EP2015/001801 to Ruppersberg filed on Sep. 7, 2015, which is entitled “Elongated Medical Device Suitable for Intravascular Insertion and Method of Making an Elongated Medical Device Suitable for Intravascular Insertion” (hereafter “the '001801 patent application”), and (b) International Patent Application PCT/EP2015/001803 to Ruppersberg filed on Sep. 7, 2015, which is entitled “Elongated Medical Device Suitable for Intravascular Insertion and Method of Making an Elongated Medical Device Suitable for Intravascular Insertion” (hereafter “the '001803 patent application”). Thus, through the '789 and '873 patent applications, this application claims priority and other benefits to the '001273 patent application, the '001801 patent application, and the '001803 patent application, as well as to the intervening '883, '671, '235 and '286 patent applications. The '576 patent application claims the benefit of U.S. Provisional Patent Application 63/032,238 filed May 29, 2020 (hereafter “the '238 patent application”), and is a continuation-in-part of the '873 patent application. The respective entireties of each of the '485, '605, '291, '346, '873, '254, '789, '576, '883, '235, 286, '605, '452, '286, and '671 patent applications are hereby incorporated by reference herein. This patent application therefore claims priority and other benefits from each of the '485, '605, '291, '346, '873, '254, '789, and '576 patent applications, and through one or more of the preceding patent applications, claims priority to the '883, '235, '286, '671 patent applications, as well as to the '001273 international patent application, the '001801 international patent application, and the '001803 international patent application.
| Number | Date | Country | |
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| 63092485 | Oct 2020 | US | |
| 63196605 | Jun 2021 | US | |
| 63221291 | Jul 2021 | US | |
| 63222346 | Jul 2021 | US | |
| 63032238 | May 2020 | US |
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