The present application is directed to detection of electrode wire noise.
Probes, such as catheters, are used in a wide range of applications, including situations in which it is important to understand the location of the probe. Probes can be used during surgical procedures, such as cardiac surgical procedures in which a surgeon tracks a position of the probe relative to the anatomy of the heart. A surgeon typically must deflect or flex a tip of the probe during a procedure by using some type of actuator, such as a knob or piston, integrated within a handle of the probe. Due to the sensitive nature of the electronics within the probe, this displacement of the distal tip of the probe causes interference or noise, which is undesirable and makes it difficult to obtain accurate readings from electrodes within the distal tip of the probe.
Accordingly, it would be desirable to provide a solution that addresses noise or interference related issues associated with deflection of the probe's distal tip.
In one aspect, a method is disclosed that detects electrode wire noise in a probe. The method includes arranging a sensor in a probe, and the probe includes a distal tip with a plurality of electrodes connected to a plurality of electrode wires and an actuator configured to displace the distal tip. The method includes detecting, via the sensor, at least one of: (i) a position of the actuator during displacement of the distal tip, or (ii) noise generated by the plurality of electrode wires during displacement of the distal tip.
In another aspect, a probe assembly is disclosed that includes a probe defining a distal tip with a plurality of electrodes connected to a plurality of electrode wires, and an actuator configured to displace the distal tip. The assembly includes a sensor configured to detect at least one of: (i) a position of the actuator during displacement of the distal tip, or (ii) noise generated by the plurality of electrode wires during displacement of the distal tip.
Information from the sensor in either (i) or (ii), in both the method and the system, is then used or further processed to identify intervals or episodes during which there is either an unacceptably high amount of displacement of the actuator, or an unacceptably high amount of noise in the electrode wires such that signals from the electrode wires will experience noise.
Multiple different aspects and components of the method and system are described herein.
A more detailed understanding can be had from the following description, given by way of example in conjunction with the accompanying drawings wherein:
As disclosed herein, systems, apparatuses and methods are provided that address issues related to static friction, noise, and other types of interference associated with engaging the actuator in a probe to displace a distal tip of the probe.
The term probe is used interchangeably with the term catheter herein, and one skilled in the art would understand that any type of sensing device could be implemented with the configurations disclosed herein.
As used herein, the term noise is generally used to refer to any unwanted disturbance of a signal. Noise can generally cause errors or undesired random disruptions in electrical signals.
In one aspect, the disclosed subject matter provides an arrangement in which deflection tracking is implemented within a probe assembly. Based on this tracking, any noise or interference can be identified and then filtered out of the signals generated by electrodes in the probe assembly.
In one aspect, at least one sensor 5 is attached directly to the patient's body. In one embodiment, the sensor 5 is a patch that is configured to detect magnetic and/or electrical signals. In one embodiment, the sensors 5 are configured to measure impedance among the sensors 5. In another aspect, at least one single-axis magnetic sensor mounted on the catheter tip is configured to work in conjunction with at least one external magnetic sensor in a patient pad (i.e. under the patient). In one embodiment, there are three magnetic sensors mounted on the catheter that are oriented in three different directions (i.e. spaced 120 degrees apart) and that are configured to work in conjunction with three external magnetic sensors. Details of such technique are provided in the following documents: U.S. Pat. Nos. 5,391,199, 5,443,489, 5,558,091, 6,172,499, 6,177,792, 6,690,963, 6,788,967, and 6,892,091, which are each incorporated by reference as if fully set forth herein. In another aspect, an impedance sensor on the catheter is provided that is configured to be used without any external sensors. Details of such technique are provided in the following documents: U.S. Pat. Nos. 5,944,022, 5,983,126, and 6,456,864, which are each incorporated by reference as if fully set forth herein. These sensors generally assist with modeling a patient's respiratory cycle, identifying when a patient's lungs are breathing in or out, and tracking a location of the probe.
One skilled in the art would understand based on the present disclosure that the embodiments disclosed herein are not limited to a heart and can be implemented to analyze any type of body part or organ. On a monitor 3, the surgeon views various data sets and models related to respiration, probe motion and location, and probe-heart motion and location. The monitor 3 can be configured to display data regarding signals detected by the probe and the sensor.
The probe 1 is also referred to as a probe assembly herein. The probe 1 can include a handle 1a, a distal tip 1b, and a proximal portion 1c connected to a computing system 4. The handle 1a includes an actuator 10, which is shown more clearly in
The computing system 4 is configured to implement various processes and algorithms disclosed herein. The computing system 4 can include a control unit 4a, a processor 4b, and a memory unit 4c. The control unit 4a can be configured to analyze signals from the probe 1 and sensors to determine coordinates and positions of the probe 1 as well as various other information. The memory unit 4c can be of various types, and is generally configured to track position data, respiration data, time data, and other types of data regarding the probe 1 and sensors. The computing system 4 can be configured to implement any of the steps, processes, methods, configurations, features, etc., that are disclosed herein.
As shown in
As shown in
The sensor 30 can be connected directly to the computing system 4, or to a printed circuit board or electrical circuitry 15 provided in the probe 1 between the sensor 30 and the computing system 4, or can be configured to transmit signals wirelessly. One skilled in the art would understand that the specific configuration of the electrical components of the probe 1 can vary.
The actuator 10 is shown generically in
In one aspect, the sensor 30 is configured to detect at least one of: (i) a position of the actuator 10, or (ii) noise generated by at least one wire 21 connected to an electrode 20 in the distal tip 1b of the probe 1. In a general aspect, the sensor 30 is configured to detect interference or noise experienced by the wires 21 connected to the electrodes 20. This configuration can be implemented in a variety of ways, such as by tracking the position or movement of the actuator 10 or by tracking impulses, tension, displacement, noise, or electrostatic experienced directly by the wires 21 connected to the electrodes 20. One skilled in the art would recognize based on the present disclosure that other configurations can be implemented to identify the noise or interference experienced by the wires 21.
The sensor 30 disclosed herein can be implemented in a variety of ways. For example, the sensor 30 can be implemented as: a capacitive displacement sensor, a sliding resistor displacement sensor, an optical encoder, a Hall-effect sensor, piezoelectric sensor, or any other type of sensor. In one embodiment, the sensor 30 consists of electrical sensing wires, which are described in more detail herein.
The handle 1a of the probe 1 can include various chambers or cavities. As shown in
As shown in
In one embodiment, the sensor 30 is implemented as force sensing linear potentiometer. As the actuator 10 is displaced due to manual manipulation, the actuator 10 can engage a strip or pad configured to deflect or otherwise be manipulated by the actuator 10. As the actuator 10 moves, the sensor 30 can detect a position of the actuator 10, which is then transmitted to the computing system 4. In other words, the sensor 30 detects a relative position of the actuator 10 and then an output signal, such as a resistance value, is provided to indicate a position of the actuator 10.
In another embodiment, the sensor 30 is implemented as a conductive film sensor assembly. For example, a semi-conductive material layer can be applied to the actuator 10. The semi-conductive material layer can be shrink wrapped around the actuator 10, and a corresponding sensor 30 can be arranged to detect a position of the actuator 10.
As disclosed in the various embodiments, a sensor 30 is provided that generally detect a position of the actuator 10. Based on the position of the actuator 10, the computing system 4 is configured to determine a velocity of the actuator 10. In general, the greater the speed or velocity of the actuator 10, then the greater the resulting noise or interference experienced by the electrode wires 21.
In any one of the arrangements disclosed herein, the sensor 30 can consist of an accelerometer, or can include a secondary sensor in the form of an accelerometer. As shown in
In any one of the configurations disclosed herein, the sensor 30 provides information regarding displacement of the actuator 10 of the probe 1 that controls deflections or flexing of the electrodes 20 provided at the distal tip 1b of the probe 1. This information can then be used by the computing system 4 in order to determine a velocity of the actuator 10. Using this information, the computing system 4 can then identify time periods during which the actuator 10 is being displaced above a threshold velocity. If the actuator 10 is moving above a predetermined threshold velocity, then the computing system 4 can filter out signals or data obtained during those time intervals because the data or information obtained during those time intervals have a high likelihood of suffering from noise or interference. In one aspect, a relatively fast threshold velocity is 10 cm per second, and a relatively slow threshold velocity is 0.5-1.0 cm per second. Signals detected during the fast movement can be blanked out or further processed. One skilled in the art would understand that these values can vary depending on catheter design and translational movement, as well as tension. This noise or interference makes it difficult for surgeons to ascertain accurate electrophysiological signals being detected by electrodes 20 in the distal tip 1b of the probe 1. In other aspects, the sensor 30 is configured to detect acceleration of the actuator 10.
A cable sheath 1e is shown in
All of the wires 21, 38a, 38b are commonly connected to electrical circuitry 15, which is shown schematically in
The sensing wires 38a, 38b are not connected to any of the electrodes 20 defined by the distal tip 1b of the probe 1 and are isolated from the electrodes 20. Instead, the sensing wires 38a, 38b terminate at some area (such as area 1d in
For illustrative purposes and to simplify the drawing, only one electrode wire 21 is shown in
The sensor 30 formed by the sensing wires 38a, 38b is configured to track and identify noise caused by friction, and more specifically cause by electrostatic friction associated with the electrode wires 21. The sensing wires 38a, 38b can be provided in any region of the probe 1, including the handle 1a, distal tip 1b (short of the electrodes 20), or proximal portion 1c. Because the sensing wires 38a, 38b do not connect to electrodes, the sensing wires 38a, 38b do not generate any local signal measurements regarding a patient's tissue. Instead, the sensing wires 38a, 38b are specifically configured to be affected by noise generated by the electrode wires 21. As electrostatic is generated by movement of the electrode wires 21 during deflection, then a potential of the sensing wires 38a, 38b is modified, causing a voltage change that can be measured and used to detect the presence of electrostatic discharge. In this aspect, the sensing wires 38a, 38b therefore function and operate as a sensor.
In one aspect, the computing system 4 is configured to receive signals from the sensor 30 (regardless of how it is implemented or embodied, i.e. as a displacement sensor, sensing wires, or any other configuration), and to identify noise or interference due to the electrode wires 21 being under tension, moved, or otherwise impacted while the actuator 10 is engaged.
The computing system 4 can be configured to filter or blank out intervals of signals generated by the electrode wires 21 during periods when the noise is above a predetermined noise threshold. In other words, the computing system 4 is configured to identify specific episodes during which there is an unacceptable level of noise and can automatically filter out those episodes. The quantity of noise can vary based on circuit design, as one skilled in the art would understand based on the present application.
In one aspect, if a resistor having a relatively lower resistance (i.e. 1Ω) is used, then the resulting detected voltage would generally also be low. In another aspect, if a resistor having a relatively higher resistance (i.e. 10 M Ω) is used, then the resistor will detect much greater noise from the power outlet. Accordingly, a resistor having relatively moderate resistance (i.e. 5 KΩ−50 KΩ) is generally preferable in one aspect. A baseline level of noise can be established by using the probe 1 in a clinical setup or setting in order to essentially calibrate the sensing configuration. This process involves identifying events of noise by intentionally generating noise, either by manual manipulation or exceeding speed thresholds of movement. Then, the noise measured by the sensing wires 38a, 38b can be compared and specific noise events can be analyzed to establish a baseline or cutoff threshold during which particularly high noise episodes can be rejected or blanked out. The data associated with these sensing steps and post filtering are shown in
Further processing steps can be performed by algorithms, processes, or other functions programmed into the computing system 4. In one aspect, addressing the unwanted noise detected by the sensors can further include rectifying the detected signal using processing, such as via a root mean square (RMS) function. The detected signal can be filtered using high pass and low pass filters. High pass filtering can remove localized components. In other words, when the signal is “floating” (i.e. not on the zero line), the baseline can be removed. Low pass filtering smooths the signals by removing high frequency components, which is shown as the “deflection sensing” data in
A flow chart is illustrated in
As shown in
Step 1020 includes a filtering step. In one aspect, the filtering step includes filtering power line noise. The filter can be a comb filter type that is configured to attenuate energy at 50 Hz and/or 60 Hz and the associated harmonics. This step is configured and calibrated to be sensitive to deflection. Step 1030 applies an absolute filter to the signals from step 1020. Step 1040 includes applying additional filters, such as a high pass (i.e. 0.5 Hz) and/or a localization filter which subtracts a local mean signal or removes the baseline. After steps 1020, 1030, and 1040,
Step 1050 includes applying a low pass filter having a predetermined setting, such as a one-second running average. This process essentially smooths out small spikes and presents an average energy value, as shown by the signals in FIG. 10D. The sensor signal (shown with dashed lines) is low in the intermediate periods when there is no energy in the ECG signal (solid line).
Step 1060 includes setting a threshold value for noise. One skilled in the art would understand that step 1060 can be performed prior to any one or more of the steps described herein. Step 1070 includes checking whether the detected signals are above the threshold. If it is determined that the detected signals are above the threshold in step 1070, then step 1080 includes detecting deflection. In one embodiment, an alert can be triggered when the threshold signal detected by the sensor is exceeded for a predetermined period (i.e. 100 ms). One skilled in the art would understand that differing alerting systems or monitoring systems can be implemented using the concepts disclosed herein.
In one aspect, the disclosed subject matter does not merely apply a filter to raw signals from the electrode wires 21 and instead uses additional information or signals collected by the sensor 30 to analyze the electrode wire signals to account for the noise caused by the actuator 10 and its deflection of the electrode wires 21.
In one aspect, when the sensor 30 is configured to detect displacement and velocity of the actuator 10, the computing system 4 can be configured to specifically blank out or filter out signals generated during intervals when the actuator 10 is moving above a predetermined velocity threshold. The computing system 4 can also be configured to apply high or low pass filters or smoothing filters or functions to the signals received by the electrodes 20 and the sensor 30. In one aspect, the signals detected by the sensor 30 can be provided to a surgeon or physician via the monitor 3 or other display means and no filtering or blanking is required.
The subject matter disclosed herein addresses issues caused by deflecting or flexing the distal tip 1b of the probe 1, which inherently causes the electrode wires 21 to be affected. By monitoring the actuator 10 or the electrode wires 21, it is possible to pinpoint moments and signals that are impacted by the deflection or flexing of the distal tip 1b of the probe 1 according to the disclosed subject matter.
The subject matter disclosed herein can be implemented using any one or more of the following Biosense Webster, Inc. components or interfaces: CARTO® 3 System Qmode+Software, Qdot Catheter, nMARQ™ RF Generator and Coolfow Pump, VISITAG® module, and Pentaray Nav Catheter. One skilled in the art would understand that the disclosed subject matter could be implemented with various other components and interfaces.
The disclosed subject matter is not limited to being used in connection with a human patient, or a patient's heart. The disclosed subject matter can be used in a variety of applications to analyze features of any type of object, such as a chamber. Additionally, the sensing configuration can be used in non-medical applications.
Any of the functions and methods described herein can be implemented in a general-purpose computer, a processor, or a processor core. Suitable processors include, for example, a general-purpose processor, a special purpose processor, a conventional processor, a digital signal processor (DSP), a plurality of microprocessors, one or more microprocessors in association with a DSP core, a controller, a microcontroller, Application Specific Integrated Circuits (ASICs), Field Programmable Gate Arrays (FPGAs) circuits, any other type of integrated circuit (IC), and/or a state machine.
Such processors can be manufactured by configuring a manufacturing process using the results of processed hardware description language (HDL) instructions and other intermediary data including netlists (such instructions capable of being stored on a computer readable media). The results of such processing can be maskworks that are then used in a semiconductor manufacturing process to manufacture a processor which implements features of the disclosure.
Any of the functions and methods described herein can be implemented in a computer program, software, or firmware incorporated in a non-transitory computer-readable storage medium for execution by a general-purpose computer or a processor.
Examples of non-transitory computer-readable storage mediums include a read only memory (ROM), a random-access memory (RAM), a register, cache memory, semiconductor memory devices, magnetic media such as internal hard disks and removable disks, magneto-optical media, and optical media such as CD-ROM disks, and digital versatile disks (DVDs).
It should be understood that many variations are possible based on the disclosure herein. Although features and elements are described above in particular combinations, each feature or element can be used alone without the other features and elements or in various combinations with or without other features and elements.