The present disclosure relates generally to electrophysiological imaging for assisting or guiding treatment procedures, and, in particular, to electrophysiological systems and methods for imaging volumes of the body and assisting or guiding balloon ablation procedures.
Atrial fibrillation (AF) is an abnormal heart rhythm characterized by rapid and irregular beating of the atria, and may be associated with heart palpitations, fainting, lightheadedness, shortness of breath, or chest pain. The disease is associated with an increased risk of heart failure, dementia, and stroke. AF may be caused by electrical pulses generated by secondary pacers at the ostium of the pulmonary veins. Accordingly, one way of treating AF is by pulmonary vein isolation, which can include ablating the inner wall of the left atrium to form lesions that isolate the ostium of the pulmonary veins from the rest of the left atrium. Ablation can be performed in various ways, including radiofrequency (RF) ablation, ultrasonic ablation, and cryoablation. RF ablation is a conventional ablation procedure that involves powering an RF electrode to create contiguous, transmural lesions using heat energy. RF ablation suffers from some drawbacks, such as a longer procedure time and small gaps in the lesions that cause AF to return over time, and even immediately.
Balloon-based ablation procedures, such as cryoablation, are alternative AF treatment procedures that are advantageous in some respects, including a shorter procedure time and the ability to create a contiguous lesion around the pulmonary vein ostium in a single shot. In cryoablation, an inflatable cryoballoon is inflated and cooled to a temperature (e.g., below −65° C.) that causes an electrically-isolating lesion or firewall in the tissue. In conventional systems, the cryoballoon is guided to the ablation site, typically the ostium of a pulmonary vein, using fluoroscopy. As shown in
Some challenges with balloon ablation include guiding the ablation balloon (e.g., cryoballoon) to the ablation site, and ensuring that the balloon is placed and oriented to maintain contact with a full circumference of the ostium. If the balloon is misaligned during ablation, the resulting lesion can include one or more gaps which may result in reconduction and recurrence of the arrhythmia thereby requiring a re-do procedure when the AF symptoms return. Referring again to
There are some shortcomings to using X ray based angiography or venography. to guide balloon ablation procedures. For example, patients and physicians may prefer to avoid x-ray radiation emitted during such procedures. Furthermore, guiding the balloon to the ablation site and checking for leaks in the pulmonary vein-balloon interface may be an imprecise and difficult processes that requires special expertise. It may be contraindicated or unadvisable to use dye for some patients. For example, at least 20% of the population has some type of contraindication for usage of dye, including allergic reactions and kidney failure. Furthermore, due to inherent limitations of dye injection under 2D fluoroscopy, approximately 13% of residual leaks may not be apparent on venography.
There are two additional methods that can support and further assist in verifying PV occlusion and establishing optimal cryoballoon appositioning:
(i) Continuous pressure monitoring identifies PV occlusion during sinus rhythm by a loss of the A wave and a change in the amplitude (increase) and morphology of the V wave. During AF, PV occlusion is identified by an abrupt increase in the V wave amplitude with a loss of the small continuous atrial A waves;
(ii) Intra-Cardiac Echocardiography (ICE) visualizes the cryoballoon in 2D or 3D and identifies leaks by presence of “micro-bubbles” (agitated saline) as well as color Doppler flow jets.
WO 2013/022853 and US 2017/347896 each disclose balloon ablation systems and methods, in which impedance sensing is used to distinguish between conduction paths through tissue and conduction paths through blood, in order to determine if the balloon has provided the desired occlusion. WO2018/207128 discloses balloon ablation system using catheter electrodes to image the heart and also to provide leakage detection.
The invention is defined by the claims and they define devices, systems methods, computer program products and computer readable media comprising the computer program products all for assisting (for example guiding) a balloon ablation therapy procedure using an ablation balloon for occluding a cavity of a subject during the procedure.
All of these aspects relate to the use of data that represent one or more electrical signals measured using one or more of a plurality of electrodes disposed on an elongate tip member (122) of an electrophysiology catheter (120) when one or more of the plurality of electrodes are positioned distally of the ablation balloon (30) in the anatomical cavity wherein the electrical signals are responsive to local dielectric properties within the anatomical cavity and were measured responsive to injection of a dielectric medium into the anatomical cavity. The data may be processed to identify a change of at least one characteristic of the one or more electrical signals where the at least one change is responsive to the injection of the dielectric medium; to determine from the identified at least one change occlusion information relating to the occlusion of the anatomical cavity by the ablation balloon. Optionally the output data is generated comprising the occlusion information. The output data may be provided to a user such as a physician, surgeon, caregiver or even the subject such as for example a caregiver performing the procedure.
The occlusion information may assist the user in performing the procedure as the occlusion information may be of relevance to and/or of influence on for example the course and/or outcome of the procedure. For example, occlusion information indicating full occlusion during the procedure may prompt a user to start an ablation. Alternatively, occlusion information indicating incomplete occlusion may be used by the user to try and improve occlusion for example to achieve full occlusion. The occlusion information may guide the user in performing the procedure.
It was found that injection of a dielectric medium with dielectric properties different from those of blood may alter the local dielectric properties in the vicinity of the point of injection of such dielectric medium in a blood containing anatomical cavity. The electrodes of the EP catheter can be used to register changes of the local dielectric properties due to the injection by measuring electrical signals, such as for example voltages and/or currents, on the electrodes of the EP catheter before during and after injection of the medium when the electrodes are positioned in the blood pool of the anatomical cavity distally of the balloon used during the ablation procedure. By identifying the changes in the signals occlusion information can be deduced.
The data processing allows the use of a dielectric medium and this may improve the detection of small leaks during occlusion with the procedure.
Being able to generate or having the occlusion information may obviate the use of X-ray based contrast agent dependent fluoroscopy, angiography or venography which currently are used to check for small leaks. The current aspects allow a dielectric medium (dielectric contrast agent) based detection of small leaks during an occlusion and such dielectric medium need not be X-ray absorbing or emitting. Note however, that in the current aspects an X-ray absorbing contrast agent (as for example known in the art) may still be used as long as it can serve as a dielectric medium in the context of the current disclosure.
In some embodiments or examples of the proposed aspects the at least one change of characteristic comprises one or more of: the amplitude of a signal spike; the time decay of a signal spike; and a comparison of the signal amplitude before and after a signal spike.
In some embodiments or examples of the proposed aspects the data represent a plurality of electrical signals each one measured using one of the plurality of electrodes and wherein the data processor is configured to identify the at least one change of the characteristic for each of the plurality of signals.
In some embodiments or examples of the proposed aspects, for example by configuring the processor circuit or data processor to this end, based on the change of the at least one characteristics, changes in local dielectric properties within the cavity are determined.
In some embodiments or examples of the proposed aspects the electrical signals further comprise baseline electrical signals measured when the anatomical cavity is not occluded by the ablation balloon. In such case, for example by configuring the processor circuit and/or the data processor to this end, a degree of occlusion is determined using a model based on a comparison of the baseline signal to a signal obtained after or during occlusion. In some of these embodiments or examples, for example by configuring the processor circuit and/or the data processor to this end, an amount of the identified change of the baseline signal before occlusion and after occlusion is compared to a threshold and when the amount of change exceeds the threshold a regional occlusion is determined to exist.
In some embodiments or examples of the proposed aspects, for example by configuring the processor circuit and/or the data processor to this end, shadow position indication of the electrophysiology catheter in the vicinity of the location at which the occlusion determination is to be obtained is used to determine therefrom one or more of: the distance from the elongate tip member to the mapping data; the distance from the elongate tip member to the ostium of a pulmonary vein of the region interest; and the current distance from the elongate tip member to the shadow position.
In some embodiments or examples of the proposed aspects, for example by configuring the processor circuit and/or the data processor to be able to communicate with the one or more of a plurality of electrodes disposed on the elongate tip member (122) of the electrophysiology catheter (120), the one or more of the plurality of electrodes are controlled measure the electrical signals. This may entail controlling these electrodes to provide electrical signals in order to invoke or cause the electrical signals to be measured.
In some embodiments or examples of the proposed aspects, for example by configuring the processor circuit and/or the data processor to this end, the occlusion information is generated to comprise a visualization of at least part to of the occlusion information indicating whether the ablation balloon at least partially occludes the anatomical cavity corresponding to, near, or at a location of each of the one or more of the plurality of electrodes.
In some embodiments or examples of the proposed aspects, for example by configuring the processor circuit and/or the data processor to this end, data representative of a map of at least part of the anatomical cavity relevant to the procedure is used to generate the map, a visualization of the occlusion information is generated and output data comprising the map and the visualization is generated. The visualization on the map may be generated as an overlay. The visualization can indicate a location of a gap between the ablation balloon and the anatomical cavity.
In some embodiments or examples of the proposed aspects, for example by configuring the processor circuit and/or the data processor to communicate with the one or more of the plurality of electrodes and with a plurality of external body patch electrodes for positioning on a subject to apply an electrical field to at least the anatomical cavity using body patch electrical signals, the external body patch electrodes are controlled to provide the electrical field; the one or more of the plurality of electrodes are controlled to detect distortions in the generated electrical field and the map data are generated to comprise the detected distortions; and, based on the detected distortions, a map of the anatomical cavity relevant to the procedure is generated.
In embodiments the processor circuit is configured to control each of the one or more electrodes of the plurality of electrodes to emit a respective electrical signal at a different frequency; and receive the respective electrical signals from other electrodes of the one or more of the plurality of electrodes.
In embodiments, the processor circuit is configured to: receive, via an input, lesion validation data of a region of a wall of the anatomical cavity; determine, based on the lesion validation data, whether any gaps exist in a lesion created by the ablation balloon.
In embodiments, the processor circuit is configured to communicate with the one or more of the plurality of electrodes and to control the plurality of electrodes to obtain lesion validation data of a region of the wall of the anatomical cavity; determine, based on the lesion validation data, whether any gaps exist in a lesion created by the ablation balloon.
In such embodiments output data may be generated that comprise an indication of whether the gaps exist in a lesion and such lesion output data may be provided to a user interface for providing the indication to a user.
According to an aspect there is proposed a system comprises a device as claimed in any of the previous claims wherein the processor circuit comprises an output, communicatively coupled to the data processor; and a user interface communicatively coupled to the processor circuit at least via the output and configured to provide an indication of the occlusion information to a user.
In some embodiments the system comprises a controller for communicatively coupling to the one or more of the plurality of electrodes and to the plurality of body patch electrodes, and communicatively coupled to the processing circuit, the controller being configured to supply any electrical signals for any electrodes upon control of any of the electrodes by the processing circuit;
In some embodiments the system comprises an injection system for injecting the medium, and optionally a vessel comprising the medium.
In some embodiments the system comprises the ablation balloon (30); and the electrophysiology catheter (120). The ablation balloon preferably is part of a balloon ablation catheter comprising the electrophysiology catheter.
In another aspect there is proposed a method for assisting a balloon ablation therapy procedure using an electrophysiology catheter and ablation balloon for occluding a cavity of a subject during the procedure during which procedure data are generated that represent one or more electrical signals measured using one or more of a plurality of electrodes disposed on an elongate tip member (122) of the electrophysiology catheter (120) when one or more of the plurality of electrodes are positioned distally of the ablation balloon (30) in the anatomical cavity and wherein the electrical signals are responsive to local dielectric properties within the anatomical cavity and were measured responsive to injection of a dielectric medium into the anatomical cavity, the method comprising: receiving, at an input of a processor circuit, the data; processing, by a data processor communicatively coupled to the input, the received data and identify a change of at least one characteristic of the one or more electrical signals where the at least one change is responsive to the injection of the dielectric medium; determining, by the data processor, from the identified at least one change occlusion information relating to the occlusion of the anatomical cavity by the ablation balloon; and optionally, provide, using a user interface communicatively coupled to an output of the processor circuit and communicatively coupled to the data processor, the occlusion information to a user.
There are proposed a computer program products comprising instructions for implementing any method as defined herein when the it is run on a processor circuit and/or data processor of the device as defined herein.
There are proposed computer readable media comprising the computer program products as defined herein.
Embodiments of the methods, computer program products and the computer readable media including the same have been described herein above. Thus any steps and features defined for the device and/or system may be used to define steps and features of the method, computer program product and media comprising such computer program product.
Other examples and embodiments may be defined as follows.
an ablation balloon;
an electrophysiology catheter comprising an elongate tip member configured to be positioned distally of the ablation balloon;
a plurality of electrodes positioned on the elongate tip member; and
an apparatus for guiding ablation within a cavity of a heart, comprising a processor circuit in communication with the electrophysiology catheter, wherein the processor circuit is configured to:
Aspects of the present disclosure thus provide systems, devices, and methods for guiding an ablation procedure. For example, in one embodiment, an apparatus includes a processor circuit configured to control an electrophysiology (EP) catheter to emit and detect electrical signals indicating blood flow near the electrodes. The EP catheter can be positioned near an ablation balloon during placement at the pulmonary vein (PV) ostium, and prior to ablation. Based on the blood flow (or lack thereof) detected by the EP catheter based on analysis of dielectric properties, the apparatus can determine whether any gaps are present at the interface between the balloon and the PV ostium. Further, in some embodiments, the apparatus can determine the location of the gaps to aid a physician in repositioning the balloon. Accordingly, the ablation procedure may be advantageously guided by the apparatus without the use of fluoroscopy, angiography, and/or contrast agent.
In some embodiments, the processor circuit is configured to determine a degree of occlusion of the balloon on the region of interest. In some embodiments, the processor circuit is configured to determine the degree of occlusion using a model based on a comparison of a pre-occlusion baseline signal to a signal obtained after occlusion of the region of interest. In some embodiments, the processor circuit is configured to compare an amount of change between the pre-occlusion baseline signal and the signal obtained after occlusion to a threshold, and the processor circuit is configured to determine regional occlusion when the amount of change exceeds the threshold. In some embodiments, the processor circuit is configured to control the plurality of electrodes to: obtain mapping data of the cavity of the heart; generate, based on the mapping data obtained by the electrode assembly, a map of the cavity of the heart, wherein the map includes a region of interest for ablation; and output, to a display in communication with the processor circuit, the map of the cavity of the heart and a second visualization of a position of the balloon within the cavity in the map.
In some embodiments, the processor circuit is in communication with a plurality of external body patch electrodes configured to be positioned on a body of a patient. In some embodiments, the processor circuit is configured to: control the external body patch electrodes to emit electrical fields into the cavity of the heart; control the plurality of electrodes to detect distortions in the electrical fields; and generate the mapping data based on the detected distortions in the electrical fields. In some embodiments, the processor circuit is configured to overlay the second visualization on the map of the cavity of the heart at the region of interest, wherein the second visualization indicates a location of a leak between the balloon and the region of interest. In some embodiments, the processor circuit is configured to: control the plurality of electrodes to obtain lesion validation data of the region of interest; determine, based on the lesion validation data, whether any gaps exist in a lesion created by the balloon; and output, to the display, a third visualization indicating whether gaps exist in the lesion. In some embodiments, the processor circuit is configured to overlay the third visualization on the map of the cavity of the heart at the region of interest, wherein the third visualization indicates a location of a gap in the lesion. In some embodiments, the processor circuit is configured to control each of the plurality of electrodes to: emit a respective electrical signal at a different frequency; and receive the respective electrical signals from other electrodes of the plurality of electrodes. In some embodiments, a system includes the processor circuit described herein and the electrophysiology catheter. The electrophysiology catheter may include an elongate tip member configured to be positioned distally of the balloon, wherein the plurality of electrodes is positioned on the elongate tip member.
The invention also provides a method for guiding ablation within a cavity of a heart, comprising:
controlling, by a processor circuit, a plurality of electrodes of an electrophysiology catheter to emit and detect a plurality of electrical signals, wherein the plurality of electrodes are formed on an elongate tip member of an electrophysiology catheter positioned distally of an ablation balloon;
detecting, based on the detected plurality of electrical signals, changes in local dielectric properties within the cavity of the heart distally of the ablation balloon;
determining, based on the changes in dielectric properties, information relating to the occlusion by the ablation balloon of a region of interest, based on the response of one or more of the detected plurality of electrical signals to injection of a medium; and
outputting, to a display in communication with the processor circuit, a first visualization indicating said information relating to the occlusion by the ablation of the region of interest.
In some embodiments, the method further comprises controlling, by the processor circuit, the plurality of electrodes to: obtain mapping data of the cavity of the heart; and generate, based on the mapping data obtained by the electrode assembly, a map of the cavity of the heart, wherein the map includes a region of interest for ablation. The method may further comprise outputting, to a display in communication with the processor circuit, the map of the cavity of the heart and a second visualization of a position of the balloon within the cavity in the map. In some embodiments, the method further includes controlling, by the processor circuit, a plurality of external body patch electrodes positioned on a body of the patient to emit electrical fields into the cavity of the heart; controlling the plurality of electrodes to detect distortions in the electrical fields; and generating the mapping data based on the detected distortions in the electrical fields.
In some embodiments, the method further includes overlaying the second visualization on the map of the cavity of the heart at the region of interest, wherein the second visualization indicates, on the map, a location of a leak between the balloon and the region of interest. In some embodiments, the method further comprises: controlling the plurality of electrodes to obtain lesion validation data of the region of interest; determining, based on the lesion validation data, whether any gaps exist in a lesion created by the balloon; and outputting, to the display, a third visualization indicating whether gaps exist in the lesion.
In some embodiments, the method further comprises overlaying the third visualization on the map of the cavity of the heart at the region of interest, wherein the third visualization indicates a location of a gap in the lesion. In some embodiments, the method further comprises controlling each of the plurality of electrodes to: emit a respective electrical signal at a different frequency; and receive the respective electrical signals from other electrodes of the plurality of electrodes.
According to another embodiment of the present disclosure, a computer program product includes a non-transitory computer-readable medium having program code recorded thereon. The program code includes: code for causing a processor circuit to control a plurality of electrodes of an electrophysiology catheter to emit and detect a plurality of electrical signals; code for causing the processor circuit to detect, based on the detected plurality of electrical signals, blood flow within the cavity of the heart; code for causing the processor circuit to determine, based on the detected blood flow, whether a balloon at least partially occludes a region of interest; and code for causing the processor circuit to output, to a display in communication with the processor circuit, a visualization indicating whether the balloon at least partially occludes the region of interest.
Additional aspects, features, and advantages of the present disclosure will become apparent from the following detailed description.
Illustrative embodiments of the present disclosure will be described with reference to the accompanying drawings, of which:
For the purposes of promoting an understanding of the principles of the present disclosure, reference will now be made to the embodiments illustrated in the drawings, and specific language will be used to describe the same. It is nevertheless understood that no limitation to the scope of the disclosure is intended. Any alterations and further modifications to the described devices, systems, and methods, and any further application of the principles of the present disclosure are fully contemplated and included within the present disclosure as would normally occur to one skilled in the art to which the disclosure relates. For example, although the following disclosure may refer to embodiments that include cryoablation procedures, cryoballoons, cryocatheters, RF balloon ablation, or RF balloons, it will be understood that such embodiments are exemplary, and are not intended to limit the scope of the disclosure to those applications. For example, it will be understood that the devices, systems, and methods described herein are applicable to a variety of treatment procedures in which a balloon is used to occlude a body lumen or body cavity. In particular, it is fully contemplated that the features, components, and/or steps described with respect to one embodiment may be combined with the features, components, and/or steps described with respect to other embodiments of the present disclosure. For the sake of brevity, however, the numerous iterations of these combinations will not be described separately.
As mentioned above, fluoroscopy-based approaches used in guiding balloon ablation procedures, including navigation and deployment of the balloon at the PV ostium and detecting leaks between the PV ostium and the ablation balloon suffer from various drawbacks. It may be desirable to provide an approach for guiding a full ablation procedure without using fluoroscopy and/or contrast agent. The present disclosure provides systems, methods, and devices for guiding a balloon ablation procedure using EP imaging and EP-based leak detection techniques. As will be further described below, an electrophysiology system can be used to provide for image-guided delivery of a balloon ablation device, such as a cryoballoon or RF balloon, into a body cavity, such as the left atrium, and to facilitate a fully-occluding placement of the cryoballoon at an ablation site.
A region of interest of a subject can comprise an anatomical cavity of the subject such as a chamber of a heart and or a part of a vessel (artery or vein) connected to such chamber.
The distal portion 122 of the EP catheter may comprise a plurality of electrodes positioned on the elongate tip member. In some embodiments, the EP catheter comprises between 8 and 10 electrodes. However, the EP catheter can include other numbers of electrodes, including 2, 4, 6, 14, 20, 30, 60, or any other suitable number of electrodes, both larger and smaller. The elongate tip member may be configured to be positioned distally of the cryoballoon, and may be biased, shaped, or otherwise structurally configured to assume a shape, such as a circular shape, in which the electrodes are spaced from one another about one or more planes. For example, the EP catheter can be a spiral mapping catheter (SMC) in which electrodes are distributed along an elongate tip member in a spiral configuration, e.g. with a 15 mm, 20 mm or 25 mm loop diameter. In some embodiments, commercially-available EP catheters can be used with the system 100, including the Achieve™ and Achieve Advance™ Mapping catheters manufactured by Medtronic™. The EP catheter can be designed for use with the Arctic Front™ Family of Cardiac Cryoablation Catheters and/or the FlexCath™ Advance Steerable Sheath, manufactured by Medtronic™. In some embodiments, the cryoballoon 132 comprises a plurality of electrodes positioned on an exterior surface of the cryoballoon 132 and configured to obtain data used to determine occlusion at an ablation site. Further details regarding EP catheters and assemblies can be found in, for example, U.S. Pat. No. 6,002,955, titled “Stabilized Electrophysiology Catheter and Method for Use,” the entirety of which is hereby incorporated by reference.
The system 100 further comprises a plurality of body patch electrodes 140 and a reference patch electrode 142 communicatively coupled to a patch electrode interface 116, which is in communication with the mapping and guidance system 114. For example, the patch electrodes 140 and the reference electrode 142 may be coupled to the patch electrode interface 116 via electrical cables. In the embodiment shown in
A more detailed explanation of the use of body patch electrodes and catheter electrodes to map body volumes and visualize the locations of EP catheters within the map can be found in, for example, U.S. Pat. No. 10,278,616, titled “Systems and Methods for Tracking an Intrabody Catheter,” and U.S. Pat. No. 5,983,126, titled “Catheter Location System and Method,” the entireties of which are hereby incorporated by reference as well as in publications WO2018130974 and WO2019034944 of the corresponding international patent applications the entireties of which are herein incorporated by reference.
For completeness, an outline will be presented of the imaging function. The electrodes of the EP catheter may be labelled “internal electrodes” and the patch electrodes may be labelled “external electrodes”. A distance between each of the internal electrodes (inter-electrode spacing) and their corresponding electrical weight lengths are predetermined and hence known.
The mapping guidance system 114 is configured to provide and receive signals from the electrodes to perform a cardiac dielectric imaging process. It provides 3D electro-anatomical visualization for guiding catheter-based treatment of cardiac arrhythmias. It utilizes wide-band dielectric sensing and a technology based on the bending of electric fields to generate high-resolution ‘CT-like’ full 3D images as well as flattened 3D panoramic views of the cardiac anatomy. Sensor-less diagnostic and ablation EP catheters are prequalified to operate with the system.
The system generates a global low intra-body electrical field by the set of external sensors, which are differentially excited, together with a local electrical field via the internal electrodes on the indwelling catheter. The internal and external electrodes are all both emitters and receivers in the frequency range of 20 kHz-100 kHz. A right leg sensor serves as an electric reference for all voltage measurements (creating a V-space).
The distribution of the induced electric field is inherently inhomogeneous due to the different dielectric properties and absorption rates (related to conductivity) of the interrogated tissues. The external electrodes measure the global general effects and distorted electric field whereas the internal electrodes measure the local effect and tissue response.
Throughout the imaging process, the imaged volume continuously grows at the sampling rate of 100 Hz. An optimal transfer function is used to transform the voltages to Euclidian coordinates (creating an R-space) while maintaining the known pre-qualified catheter characteristics (electrode spacing and electrical weight length, functioning as an internal ruler) as well as a set of other constraints. This transfer function is repeatedly defined and applied globally.
Using the updated R-space cloud of points a reconstruction algorithm generates a 3D image. Regions with inherently marked steep gradients in the electric field (i.e. drainage of vessels into or out of a cardiac chamber as well as the A-V and V-A valves) are picked up uniquely by the system and imaged even without physically visiting them with the catheter. The system thus can image at locations beyond the catheter.
The continuous combined global and local field measurements enable sophisticated continuous detection and effective handling of inconsistencies and outliers, level of electrode coverage (by measuring inter-correlations), pacing (saturation), as well as physiological drift.
Drift is detected by applying a moving window over time and applying continuous correction whereby the catheter location remains accurate throughout the whole procedure making the system resilient to drift. Cardiac and respiratory motion are also compensated.
For imaging, at least two electrodes on a catheter/wire/pacing lead are necessary, whereas even a single electrode can be spatially localized after the initial obligatory computation of the R-field The system has been proposed for guiding CryoBalloon (CB) Pulmonary Vein Isolation (PVI) procedures while potentially minimizing exposure to fluoroscopy and obviating dye injection.
In the diagram shown in
The mapping and guidance system 114 is coupled to a display device 118, which may be configured to provide visualizations of a cryoablation procedure to a physician. For example, the mapping and guidance system 114 may be configured to generate EP images of the body cavity, visualizations of the propagation of EP waves across the tissue of the body cavity, indications of occlusion by the cryoballoon at an ablation site, or any other suitable visualization. These visualizations may then be output by the mapping and guidance system 114 to the display device 118.
The processor 160 may include a central processing unit (CPU), a digital signal processor (DSP), an ASIC, a controller, an FPGA, another hardware device, a firmware device, or any combination thereof configured to perform the operations described herein. The processor 160 may also be implemented as a combination of computing devices, e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration.
The memory 164 may include a cache memory (e.g., a cache memory of the processor 160), random access memory (RAM), magnetoresistive RAM (MRAM), read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read only memory (EPROM), electrically erasable programmable read only memory (EEPROM), flash memory, solid state memory device, hard disk drives, other forms of volatile and non-volatile memory, or a combination of different types of memory. In an embodiment, the memory 164 includes computer-readable medium, which may be a non-transitory computer-readable medium. The computer-readable medium may store instructions. For example, the memory 164, or computer-readable medium may have program code recorded thereon, the program code including instructions for causing the processor circuit 150, or one or more components of the processor circuit 150, to perform the operations described herein. For example, the processor circuit 150 can execute operations described with reference to
The communication module 168 can include any electronic circuitry and/or logic circuitry to facilitate direct or indirect communication of data between the processor circuit 150, the mapping and guidance system 114, the EP catheter 120, the cryoballoon catheter 130, and/or the display 118. In that regard, the communication module 168 can be an input/output (I/O) device. In some instances, the communication module 168 facilitates direct or indirect communication between various elements of the processor circuit 150 and/or the system 100 (
In one embodiment, the device as defined herein comprises or is a computing device or a computer whether mobile or stationary. Such computing device may take the form of a workstation.
In step 206, using the images or maps acquired during step 204, the EP catheter is introduced into the left atrium using a transseptal procedure. In some embodiments, the transseptal procedure may involve the use of a transseptal needle or RF needle to penetrate the transseptal wall to introduce the catheter or sheath into the left atrium. In step 208, the features of the left atrium are imaged. For example, the atrial wall, pulmonary vein (PV) ostia, left atrial appendage (LAA), LAA ridge, mitral valve, or other features of the left atrium may be imaged using the EP catheter 120. Anatomical variations can be detected without the use of contrast media. Accordingly, all the necessary anatomical landmarks to perform the ablation procedure can be mapped using the EP catheter and output to a display to guide preplanning of the ablation process and deployment of the balloon. In that regard,
In step 212, the balloon is positioned at the ablation site (e.g., PV ostium). In some embodiments, positioning the balloon includes inflating or deploying the balloon. In some embodiments, the balloon is positioned at the ablation site using EP imaging to guide the placement. In some embodiments, the processor circuit is configured to output an image of the left atrium and a visualization of the position balloon within the left atrium. For example, in some embodiments, the processor outputs a three-dimensional visual depiction of the balloon and/or the distal portion of the EP catheter that indicates the position and orientation of the balloon within the left atrium. Using these visual depictions, the physician may position and orient the inflated balloon to achieve a full occlusion between the pulmonary vein and the cavity of the left atrium.
An inflated, electrically non-conducting, large cryoballoon naturally represents a substantial spatial interference in the distribution of the electrical fields thereby a baseline recording from the catheter electrodes may be performed with the balloon already inflated but not occluding the pulmonary vein, PV. Advancing the balloon and occlusion of the PV further changes the distribution of the local dielectric properties and when compared to the baseline recording, as long as the catheter remains approximately in the same proximal PV location, optimal balloon apposition in the PV ostia can then be determined.
In that regard,
Referring to
In some aspects, it may be difficult to ensure, using EP images alone, that full occlusion by the balloon is achieved. For example small leaks may be difficult to detect. Accordingly, in step 214, the EP catheter 120 is used to detect the presence of leaks or gaps in the interface between the balloon 132 and the ostium. As explained above, the EP catheter 120 includes a plurality of internal electrodes 124 at a distal end configured to generate and detect electrical signals used to detect or identify blood flow associated with leakage of blood from the pulmonary vein into the left atrium. Normally, blood flows from the pulmonary vein into the left atrium. Accordingly, a full occlusion of the pulmonary vein should block all blood flow from the pulmonary vein 10 into the left atrium 20. In the method 200, the EP catheter 120 is configured to detect blood flow from the pulmonary vein 10 into the left atrium 20 that should have been blocked by the balloon 132. If an amount of blood flow is detected based on the electrical signals, the system may determine that the placement of the balloon 132 is suboptimal, as it is not fully-occluding. In embodiments, the processor circuit may receive the electrode signals in a data format such that it is capable of processing such data to determine based on the signals indications of an occlusion status of the balloon. Further, in some embodiments, the system may output a visualization indicating such occlusion status which may include for example a location of the gap or leak.
The way the electrical signals from the internal electrodes may be used to detect blood flow is discussed below. The processing of data indicative of such signals to determine occlusion status is also described herein below. The signal processing may be used as such.
However, alternatively or additionally, it is possible to provide further information on occlusion status, such as for example confirmation that there is no leakage, by using an injection of a dielectrically modifying fluid during the occlusions measurements. This can be used to further increase the sensitivity of the PV occlusion test by increasing the signal to noise ratio. Embodiments therefore relate in particular to this monitoring of occlusion status and processing of EP electrode data obtained based on injection of a medium during occlusion.
Advantageously, the medium does not need to be an X-ray contrast agent (Fluoroscopic dye), but may be a less harmful and less viscous saline or dextrose-in-water (D5W) fluid. This shortens the required test time and enables a zero-fluoroscopy (zero-F) and zero-dye (zero-D) procedure. The medium used in embodiments will herein after be referred to as dielectric medium in the sense that it is a medium that has dielectric properties different from that of normal blood. An example of such property may be electrical conductivity which for normal blood is ˜6.6 mS/cm. The dielectric medium may thus have an electrical conductivity different form that of normal blood.
Referring to
Even though the balloon may be determined to be fully occluding before or during the ablation procedure, in some instances, the resulting lesion does not fully isolate the pulmonary vein from the left atrium. For example, in some instances, the balloon may move during the ablation procedure. In some instances, even though the balloon fully occludes the pulmonary vein, other aspects may cause the lesion to have gaps around the ablation site such that the lesion does not fully isolate the pulmonary vein, including insufficient ablation time, insufficient contact or pressure of the balloon on the tissue, etc. Accordingly, in some aspects, it may be beneficial to perform a post-ablation verification procedure to test or measure the effectiveness of the ablation procedure. In that regard, in step 218, the system determines or measures lesion viability using the EP catheter. If a cryoballoon is used, the cryoballoon is reheated to detach the cryoballoon from the ablated tissue to determine lesion viability. The determination of lesion viability may include a lesion visualization procedure in which the electrodes 124 of the EP catheter 120 are used to compute transmurality and/or permanency of the lesion, which may be assessed immediately after ablation.
Accordingly, the procedures described in the method 200 allow for a complete balloon ablation procedure to be performed without the use of fluoroscopy, contrast agent, or ultrasound to guide the procedure, and allow for reliable post-ablation validation to reduce the need for re-do procedures to address incomplete lesions.
In step 220, the imaging is carried out, for example generating 3D and panoramic images.
In step 221, the images are analyzed and the cryoballoon procedure is planned.
In step 222, the pulmonary vein is chosen for isolation.
In step 223, the catheter is deployed proximal to the PV position. The PV location is marked on the image, creating a shadow.
In step 224, the balloon is inflated and is then advanced to the occluding position.
In step 225, the occlusion is confirmed by injecting a dielectric modifying fluid such as saline solution or dextrose solution.
In step 226, freezing is commenced if the PV is fully occluded.
In step 227, if there is a small residual leak, the balloon is repositioned and occlusion is reconfirmed with the assistance of a dielectric modifying injection.
Steps 220 to 223 are the same as in
In step 220, the imaging is carried out, for example generating 3D and panoramic images.
In step 221, the images are analyzed and the cryoballoon procedure is planned.
In step 222, the pulmonary vein is chosen for isolation.
In step 223, the catheter is deployed proximal to the PV position. The location is marked on the image, creating a shadow.
In step 230, the balloon is inflated in a non-occluding position.
In step 231, a baseline reading with the inflated balloon near the shadow mark.
In step 232, it is verified that the catheter is near the shadow mark and the occlusion is tested. This occlusion testing relies on the baseline acquisition and is without use of a contrast medium. It for example uses detection of a change in the native catheter signals and other features (such as a pulse pattern and respiration signal, and the catheter location within the imaging coordinate system).
In step 233, the occlusion is confirmed by injecting a dielectric modifying fluid such as saline solution or dextrose solution.
Steps 226 and 227 are the same as in
In step 226, freezing is commenced if the PV is fully occluded.
In step 227, if there is a small residual leak, the balloon is repositioned and occlusion is reconfirmed with the assistance of a dielectric modifying injection.
Another possible method is to start with a baseline acquisition and gradually approach the occlusion position. The contrast injection is then used to confirm the position.
In step 408, based on the detected electrical signals, the system detects blood flow (or the lack of blood flow) in the pulmonary vein. In that regard, referring to
For example, in some aspects, blood flow may add noise to one or more electrical signals, change the average amplitude of the electrical signals, or otherwise affect the electrical signals in a way that can be detected by the system.
This detection may be performed without any injection of a dielectric medium. Additionally or alternatively, the detection makes use of the response of the the electrical signals to the injection of the dielectric medium. Before such embodiments are described, the way occlusion can be detected without the need for a dielectric medium injection to improve signal to noise ratio will be explained with reference to
By contrast,
It has been found that for situations where there is a leak, the electrode signal at which the leak is detected has a high amplitude peak with a rapid decay back to the pre-injection level. When there is occlusion, there is a less marked peak, and also slower decay. Furthermore, the value remains above the pre-injection level at the end of the measurement window.
By analyzing the signals from multiple of all of the full set of electrodes, e.g. following a spiral or circular (lasso) shape, a leakage level can be graded and can also be spatially located by comprehensively assessing all electrodes in 2D or even 3D. The detection may thus resolve between multiple small leaks at different angular positions or a single larger leak, for example.
Thus, the leak detection in particular or occlusion status in general is based on one or more electrical signals measured with one or more electrodes of an EP catheter located within a pulmonary vein during an injection of a dielectric medium in the pulmonary vein distal to the balloon during an occlusion event of for example an ablation procedure. The signal analysis is based on the response of the one or more detected electrical signals to the injection of the medium. In this way the response, e.g. the temporal response (i.e. the way that medium flows through the circulatory system) to the injection of the medium is monitored. Thus once the systems are obtained by the system and converted to appropriate data format, the processing circuit may perform the necessary processing to derive the occlusion status form the data indicative of the response.
In embodiments, the response of one or more of the detected plurality of electrical signals in response to injection of said medium comprises one or more of:
the amplitude of a signal spike;
the time decay of a signal spike; and
a comparison of the signal amplitude before and after a signal spike.
The signal amplitude before the signal spike is for example based on a measurement window before the injection and the amplitude after the signal spike is at the end of a measurement window, where the end of the measurement window may be chosen by the user, or may be preset or may be determined automatically. For example, the end of the window may correspond to decay of the spike to half maximum or some other chosen amplitude value. The end of the window may also correspond to a time stamp where the amplitude of the signal has become substantially stable over time or even have returned to a level substantially equal to the level before injection. The end of the window can correspond to e.g. of maximum duration.
The electrical signals are all gathered distally of the ablation balloon in the proximal PV position, i.e. in the cavity that is to be or is occluded by the balloon during the procedure. There are no comparison electrodes at the proximal side of the balloon, so the electrode signal analysis is based solely on the dynamic changes in dielectric properties distally beyond the balloon, i.e. within the PV 10, PV 10 being an example of such cavity.
The occlusion analysis may also provide additional clinically relevant warnings, such as based on the following measurements and warnings:
(i) Distance To Ostium (DTO)—the catheter is too distal in the vein;
(ii) Distance To Shadow (DTS)—the catheter is too far from the shadow;
(iii) Distance To Mesh (DTM)—the catheter is outside the imaged mesh.
The conductivity of the injected dielectric medium may be higher or lower compared to the blood conductivity of around 6.6 mS/cm. Preferably the conductivity of the dielectric medium is lower than that of blood. It has been observed that signal to noise ratios of the measurements are then increased with respect to measurements that do not use a contrast agent. The dielectric medium for example has a conductivity of below 1 mS/cm, for example below 0.1 mS/cm and preferably below 0.05 mS/cm. Whether higher or lower, the larger the difference between the conductivity of blood and the medium, the higher the effect (for example the higher the amplitude spike) and the higher the improvement of signal to noise ratio may be. The dye, such as for example the Omnipaque™) has a conductivity of blood and the medium, the higher the The dye, such as for example the Omnipaque™) has a conductivity lower than blood of ˜0.01 mS/cm. The data of
Referring again to
In step 412, the system is configured to output, to a display, a first visualization indicating whether the balloon occludes the region of interest. In some embodiments, the first visualization includes an indicia of full occlusion or no occlusion. For example, text, check marks, colored boxes, or other visual indicators can be used to inform the physician whether full occlusion has occurred. In some embodiments, the first visualization indicates which parts of the interface between the balloon and the ablation site are occluded, and which parts are not. For example, in some embodiments, the first visualization may be overlaid on a map of the body cavity to identify the locations of any leaks on corresponding locations in the map. In some embodiments, the first visualization may appear similar to the indicator 312 shown in
In that regard,
Referring again to
Based on the lesion validation data, the processor may determine whether the lesion likely electrically isolates the pulmonary vein from the left atrium, of if gaps exist in the lesion that allow for AF to return. In step 416, a second visualization is output the display to indicate whether the lesion is isolating. As shown in the user interface 800 of
It will be understood that one or more of the steps of the methods 200 and 400, such as generating the map of a body cavity, detecting blood flow within a body cavity or lumen using electrical signals acquired by an EP catheter, and outputting visualizations to a display indicating whether the balloon fully occludes an ablation site, can be performed by one or more components of an EP-guided ablation system, such as a processor circuit of a mapping and guidance system, an EP catheter, a cryoballoon catheter, an RF ablation balloon catheter, external body patch electrodes, or any other suitable component of the system. For example, the described ablation procedures may be carried out by the system 100 described with respect to
It will also be understood that the embodiments described above are exemplary and are not intended to limit the scope of the disclosure to a given clinical application. For example, as mentioned above, the devices, systems, and techniques described above can be used in a variety of balloon ablation applications that involve occlusion of a body cavity or body lumen. For example, in some embodiments, the techniques described above can be used to guide a cryoablation procedure using a cryocatheter comprising a cryoballoon as described above. In other aspects, the techniques described above can be used to guide an RF ablation procedure in which a plurality of RF ablation electrodes positioned on the surface of an inflatable balloon are used to create an electrically-isolating lesion in cardiac tissue. For example, the HELIOSTAR RF balloon catheter, manufactured by Biosense Webster, Inc., includes 10 ablation electrodes positioned on an external surface of the inflatable balloon, and 10 electrodes on a circular mapping catheter positioned distally of the balloon and configured to be positioned inside the pulmonary vein. Alternatively, or additionally, the electrodes positioned on the RF ablation balloon can be used to determine the contact force or tissue pressure of the balloon on the tissue to detect online potential inadvertent balloon dislodgement during the ablation process. Techniques for using electrodes to determine contact force against tissue are described in U.S. Patent Application Publication No. 2018/0116751, titled “Contact Quality Assessment by Dielectric Property Analysis,” the entirety of which is hereby incorporated by reference. Further, while the ablation procedures are described with respect to the heart and associated anatomy, it will be understood that the same methods and systems can be used to guide ablation procedures in other body volumes, including other regions of interest in the heart, or other body cavities and/or lumens. For example, in some embodiments, the EP guided ablation procedures described herein can be used to guide treatment procedures in any number of anatomical locations and tissue types, including without limitation, organs including the liver, heart, kidneys, gall bladder, pancreas, lungs; ducts; intestines; nervous system structures including the brain, dural sac, spinal cord and peripheral nerves; the urinary tract; as well as valves within the blood, chambers or other parts of the heart, and/or other systems of the body. The anatomy may be a blood vessel, as an artery or a vein of a patient's vascular system, including cardiac vasculature, peripheral vasculature, neural vasculature, renal vasculature, and/or any other suitable lumen inside the body. In addition to natural structures, the approaches described herein may be used to examine man-made structures such as, but without limitation, heart valves, stents, shunts, filters and other devices. in the kidneys, lungs, or any other suitable body volume. Further, the occlusion and flow detection features described above can be employed in various applications to determine flow occlusion. For example, the flow occlusion detection procedures described above can be used in the diagnosis and/or treatment of aneurisms, stent deployment, and any other suitable application.
Persons skilled in the art will recognize that the apparatus, systems, and methods described above can be modified in various ways. Accordingly, persons of ordinary skill in the art will appreciate that the embodiments encompassed by the present disclosure are not limited to the particular exemplary embodiments described above. In that regard, although illustrative embodiments have been shown and described, a wide range of modification, change, and substitution is contemplated in the foregoing disclosure. It is understood that such variations may be made to the foregoing without departing from the scope of the present disclosure. Accordingly, it is appropriate that the appended claims be construed broadly and in a manner consistent with the present disclosure.
Number | Date | Country | Kind |
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19184189.9 | Jul 2019 | EP | regional |
20179587.9 | Jun 2020 | EP | regional |
Filing Document | Filing Date | Country | Kind |
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PCT/EP2020/068334 | 6/30/2020 | WO |