Using Signed Distance Functions to Visualize Pulsed Field Ablation (PFA) Tags

Abstract

[0003] Systems and methods for visualization of pulsed field ablation tags are disclosed. In some implementations, the system includes a device including a processor in communication with one or more sensors and a catheter including a plurality of electrodes. In some implementations, the processor is configured to receive, via the one or more sensors, a position of each of the plurality of electrodes within a three-dimensional environment during a first ablation session, calculate, for the first ablation session, a first implicit function representing an energy field of the first ablation session from the received position of each of the plurality of electrodes, and present, via a display, a first volumetric representation of the calculated first implicit function.

Description

[Technical Field]

[0001] The present invention relates to a system and method for tracking and visualizing invasive medical procedures, and more particularly to a system and method for using signed distance functions to visualize pulsed field ablation (PFA) tags. [Background technology]

[0002] During pulsed field ablation (PFA), electrodes in a single-electrode catheter or a multi-electrode catheter, such as the VARIPULSE multi-electrode catheter manufactured by Biosense Webster, Inc. of Irvine, California, are activated to damage electrical pathways in tissue by creating non-conductive lesions. During a procedure, these electrodes may be activated multiple times, and each activation is sometimes referred to as an ablation session. Due to the number of activations, and for multi-electrode catheters, the number of electrodes, it can be difficult for physicians to understand the effects of an ablation session. Specifically, while the locations of activated electrodes on a catheter may be recorded during a procedure and displayed as a point cloud or multiple tags or markers in three-dimensional space, such a display does not show the ablation field energy received by the tissue. Additionally, energy from the electric field between the electrodes is not represented. This can be particularly noticeable over multiple ablation sessions, as energy is deposited in the tissue. Furthermore, the point cloud representation may not clearly distinguish between different ablation sessions or provide a clear indication that two points or tags were created from the same ablation session. Summary of the Invention [Means for solving the problem]

[0003] Implementations of the systems and methods described herein address these and other issues by representing each ablation session as a combination of adjacent implicit functions. In some implementations, the energy field between adjacent electrodes may be represented by a signed distance function. In many implementations, adjacent implicit functions are smoothly connected, improving the representability of the energy field received by a single catheter ablation session. In some implementations, the implicit functions may be rendered on a display in a three-dimensional environment via volumetric tracking. In some implementations, shading or color may be utilized to indicate the accumulated energy across multiple ablation sessions (e.g., darker areas indicate more accumulated energy and lighter areas indicate lower accumulated energy, or vice versa).

[0004] According to exemplary embodiments, a system for visualization of pulsed field ablation tags is provided. In some embodiments, the system includes a device including a processor in communication with one or more sensors and a catheter including a plurality of electrodes. In embodiments, the processor is configured to receive, via the one or more sensors, a position of each of the plurality of electrodes within a three-dimensional environment during a first ablation session, calculate, for the first ablation session, a first implicit function representing the energy field of the first ablation session from the received position of each of the plurality of electrodes, and present, via a display, a first volumetric representation of the calculated first implicit function.

[0005] In some embodiments, the processor is further configured to calculate a first implicit function via a signed distance function based on the positions of a pair of adjacent electrodes of the plurality of electrodes during the first ablation session. In further embodiments, the processor is further configured to calculate the implicit function via a plurality of signed distance functions, each of the plurality of signed distance functions corresponding to a different pair of adjacent electrodes. In some embodiments, the processor is further configured to calculate, for each of a plurality of voxels of the three-dimensional environment, a distance from the voxel to a position of one of the plurality of electrodes. In further embodiments, the processor is further configured to determine, for each of the plurality of voxels of the three-dimensional environment, whether the corresponding calculated distance is less than a threshold. In still further embodiments, the processor is further configured to modify a value associated with one or more of the plurality of voxels of the three-dimensional environment in response to the corresponding calculated distance being less than the threshold. In another yet further embodiment, the processor is further configured to modify a value associated with the first voxel in response to a distance from the first voxel to a location of one of the plurality of electrodes during the first ablation session being less than a threshold, and to modify a value associated with the first voxel in response to a distance from the first voxel to a location of one of the plurality of electrodes during the second ablation session being less than a threshold. In yet another yet further embodiment, the processor is further configured to present the first volumetric representation as one or more voxels in a three-dimensional environment, each voxel being shaded based on a value associated with the voxel. In yet a still further embodiment, the processor is further configured to receive, via one or more sensors, the location of each of the plurality of electrodes during the second ablation session, calculate, for the second ablation session, a second implicit function representing the energy field of the second ablation session, and present, via a display, the second volumetric representation of the calculated second implicit function together with the first volumetric representation of the calculated first implicit function.In some embodiments, the processor is further configured to classify the positions of each of the plurality of electrodes during the first ablation session into a plurality of clusters, and calculate a first implicit function for the first ablation session via a signed distance function between electrode pairs within each cluster.

[0006] In another aspect, a method for visualization of pulsed field ablation tags is provided, the method including receiving, by a processor of a device from one or more sensors, a position within a three-dimensional environment of each of a plurality of electrodes of a catheter during a first ablation session, calculating, by the processor, a first implicit function for the first ablation session from the received positions of each of the plurality of electrodes, the first implicit function representing the energy field of the first ablation session, and presenting, by the processor, via a display, a first volumetric representation of the calculated first implicit function.

[0007] In some embodiments, the method includes calculating a first implicit function via a signed distance function based on positions of a pair of adjacent electrodes of the plurality of electrodes during a first ablation session. In further embodiments, the method includes calculating the implicit function via a plurality of signed distance functions, each corresponding to a different pair of adjacent electrodes.

[0008] In some embodiments, the method includes calculating, for each of a plurality of voxels of the three-dimensional environment, a distance from the voxel to a location of one of the plurality of electrodes. In a further embodiment, the method includes determining, for each of the plurality of voxels of the three-dimensional environment, whether the corresponding calculated distance is less than a threshold. In a still further embodiment, the method includes modifying a value associated with one or more of the plurality of voxels of the three-dimensional environment in response to the corresponding calculated distance being less than a threshold. In another still further embodiment, the method includes modifying a value associated with a first voxel in response to a distance from the first voxel to a location of the one of the plurality of electrodes during a first ablation session being less than a threshold, and modifying a value associated with the first voxel in response to a distance from the first voxel to a location of the one of the plurality of electrodes during a second ablation session being less than a threshold. In yet another still further embodiment, the method includes presenting, by a processor, the first volumetric representation as one or more voxels in a three-dimensional environment, each voxel being shaded based on a value associated with the voxel. In yet a still further embodiment, the method includes receiving, via one or more sensors, a position of each of a plurality of electrodes during a second ablation session, calculating, for the second ablation session, a second implicit function representing the energy field of the second ablation session, and presenting, via a display, the second volumetric representation of the calculated second implicit function along with a first volumetric representation of the calculated first implicit function. In a further embodiment, the method includes classifying the position of each of the plurality of electrodes during the first ablation session into a plurality of clusters, and calculating, for the first ablation session, the first implicit function via a signed distance function between electrode pairs within each cluster.

[0009] According to one or more embodiments, the exemplary method embodiments described above may be implemented as an apparatus, a system, and / or a computer program product. [Brief explanation of the drawings]

[0010] This 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.

[0011] A more detailed understanding may be had from the following description, given by way of example in conjunction with the accompanying drawings, in which like reference numerals indicate similar elements and in which: [Figure 1] 1 depicts an exemplary catheter-based electrophysiological mapping and ablation system according to one or more embodiments. [Figure 2] FIG. 1 is a block diagram of an exemplary system for remotely monitoring and communicating patient biometric indicators, according to one or more embodiments. [Figure 3] FIG. 1 is a system diagram of an example computing environment in communication with a network, according to one or more embodiments. [Figure 4A] Illustrative examples of cardiomyopathy. [Figure 4B] Illustrative examples of cardiomyopathy. [Figure 4C] Illustrative examples of cardiomyopathy. [Figure 4D] Illustrative examples of cardiomyopathy. [Figure 5A] 1 illustrates an example of a linear catheter including multiple electrodes, according to one or more embodiments. [Figure 5B] 1 depicts an example of a balloon catheter with multiple electrodes, according to one or more embodiments. [Figure 5C] 1 depicts an example of a loop catheter with multiple electrodes, according to one or more embodiments. [Figure 6A] 10 is a screenshot of an example of a point cloud generated from multiple ablation sessions, according to one or more embodiments. [Figure 6B]10 is a screenshot of an example of volumetric tracing of multiple implicit functions generated from multiple ablation sessions, according to one or more embodiments. [Figure 6C] 1 is an illustration of an exemplary energy field around multiple electrodes during an ablation session, according to one or more embodiments. [Figure 6D] 6D is an illustration of an exemplary signed distance function representing the energy field around multiple electrodes during the ablation session of FIG. 6C, according to one or more embodiments. [Figure 6E] 6C is a screenshot of an example of volumetric tracking of the multiple implicit functions of FIG. 6B with a highlighted implicit function corresponding to one ablation session of the multiple ablation sessions, in accordance with one or more embodiments. [Figure 7] 1 is a flowchart of a method for visualization of pulsed field ablation tags, according to one or more embodiments. DETAILED DESCRIPTION OF THE INVENTION

[0012] During pulsed field ablation (PFA), electrodes in a single-electrode or multi-electrode catheter are activated to damage electrical pathways in tissue by creating non-conductive lesions. During a procedure, these electrodes may be activated multiple times, with each activation sometimes referred to as an ablation session. To provide visual feedback to the physician, some systems track the location of the electrodes during each ablation session and provide visualization of points or marks, sometimes referred to as tags or ablation tags, in a three-dimensional environment (e.g., representing the tissue, vessel, or other environment in which the catheter is placed).

[0013] Due to the number of activations, and for multi-electrode catheters, the number of electrodes, it can be difficult for a physician to understand the effects of an ablation session. In many implementations, the point cloud may not identify the ablation field energy received by the tissue. Additionally, in many implementations, the energy from the electric field between the electrodes is not represented. This can be particularly noticeable over multiple ablation sessions, as energy is deposited in the tissue. Furthermore, the point cloud representation may not clearly distinguish between different ablation sessions or provide a clear indication that two points or tags were created from the same ablation session.

[0014] Disclosed herein are systems and methods for visualization of pulsed field ablation tags or marks. More particularly, the present invention relates to the use of implicit functions to represent energy fields during an ablation session from multiple electrodes. The implicit function, in some embodiments, may include a combination or aggregation of signed distance functions between adjacent electrode pairs. In many embodiments, a smooth minimum function may be used to determine the energy field between adjacent electrodes during ablation. Determining the energy field may include calculating the field strength or amplitude at various points in some implementations, or may include estimating or approximating the field amplitude in other implementations. For example, in some implementations, visualization of the energy field may not require exact values; an approximation may be sufficient to use, while being faster to compute, consuming fewer resources, etc. The distance from a point in the environment (e.g., represented by a voxel) to one or more electrodes may be used to approximate the energy field in many implementations.

[0015] For example, in some implementations, an energy field may be determined based on electrode location, and an energy threshold may be assigned or determined at which ablation may be deemed sufficient. In some implementations, energy field values ​​may be converted to distances such that the distance at a provided threshold is zero. Distance values ​​may then be assigned to associated volumes such that energies below the threshold result in positive distances and energies above the threshold have negative distances. These distance values ​​may then be easily rendered as volumes or regions within a three-dimensional environment for viewing.

[0016] In other implementations that use approximations, a smooth function, such as a smooth minimum, that approximates the energy field at a given threshold may be determined. The function may be rendered as a surface, resulting in a similar visualization with significantly reduced processing requirements.

[0017] In many implementations, an ablation session may be rendered as a volumetric trace within a three-dimensional environment. The deposited energy over multiple ablation sessions may be calculated and displayed via shading or color of the volumetric trace. While many of the examples discussed herein relate to the heart, any anatomical structure, body part, organ, or portion thereof may be targeted for ablation and visualization.

[0018] Advantageously, because implicit functions use less three-dimensional data for the same or better visual fidelity, implicit functions require less processing resources and memory to render while still providing high-quality visualization. For example, each ablation session can be represented by a single aggregate implicit function with smooth boundaries, requiring fewer resources than storing a three-dimensional bitmap or array with explicit values ​​for each location or voxel in the environment.

[0019] Reference is made to FIG. 1 , which illustrates an exemplary system (e.g., medical device instrumentation and / or catheter-based electrophysiology mapping and ablation) designated as system 10, in which one or more features of the subject matter herein may be implemented according to one or more embodiments. System 10, as illustrated, includes recorder 11, heart 12, catheter 14, model or anatomical map 20, electrogram 21, spline 22, patient 23, physician 24 (or medical professional or clinician), location pad 25, electrodes 26, display device 27, distal tip 28, sensor 29, coil 32, patient interface unit (PIU) 30, electrode skin patch 38, ablation energy generator 50, and workstation 55. It should be further noted that each element and / or item in system 10 represents one or more of that element and / or item. The example system 10 illustrated in FIG. 1 can be modified to implement embodiments disclosed herein. Embodiments of the present disclosure may be applied using other system components and configurations as well. Additionally, system 10 may include additional components, such as elements for sensing electrical activity, wired or wireless connectors, a processing unit, and a display device.

[0020] The system 10 includes multiple catheters 14 that are percutaneously inserted by a physician 24 through a patient's vascular system into a chamber or vasculature of the heart 12. Typically, a delivery sheath catheter is inserted into the left or right atrium near a desired location within the heart 12. Multiple catheters can then be inserted into the delivery sheath catheter to reach the desired location. The multiple catheters 14 may include catheters dedicated to sensing intracardiac electrogram (IEGM) signals, catheters dedicated to ablation, and / or catheters dedicated to both sensing and ablation. An exemplary catheter 14 configured to sense IEGMs is illustrated herein. The physician 24 brings a distal tip 28 of the catheter 14 into contact with the heart wall to sense a target site within the heart 12. For ablation, the physician 24 similarly brings the distal end of an ablation catheter to the target site for ablation.

[0021] Catheter 14 is an exemplary catheter that includes one, and preferably multiple, electrodes 26 optionally distributed across multiple splines 22 at distal tip 28 and configured to sense IEGM signals. Catheter 14 may additionally include a sensor 29 embedded in or near distal tip 28 for tracking the position and orientation of distal tip 28. Optionally and preferably, position sensor 29 is a magnetic-based position sensor that includes three magnetic coils for sensing three-dimensional (3D) position and orientation.

[0022] The sensor 29 (e.g., a position-based or magnetic-based position sensor) may operate in conjunction with a location pad 25 that includes a plurality of magnetic coils 32 configured to generate a magnetic field within a predetermined working volume. The real-time position of the distal tip 28 of the catheter 14 may be tracked based on the magnetic fields generated by the location pad 25 and sensed by the sensor 29. Details of magnetic-based position sensing technology are described in U.S. Patent Nos. 5,5391,199; 5,443,489; 5,558,091; 6,172,499; 6,239,724; 6,332,089; 6,484,118; 6,618,612; 6,690,963; 6,788,967; and 6,892,091.

[0023] System 10 includes one or more electrode patches 38 positioned on patient 23 for skin contact to establish location references for location pads 25 and impedance-based tracking of electrodes 26. For impedance-based tracking, current is directed to electrodes 26 and sensed at patches 38, allowing the location of each electrode to be triangulated via patches 38. Details of impedance-based location tracking technology are described in U.S. Patent Nos. 7,536,218, 7,756,576, 7,848,787, 7,869,865, and 8,456,182, which are incorporated herein by reference.

[0024] Recorder 11 displays electrograms 21 captured by electrodes 18 (e.g., surface electrocardiogram (ECG) electrodes) and intracardiac electrograms (IEGMs) captured by electrodes 26 on catheter 14. Recorder 11 may include pacing capability for pacing the cardiac rhythm and / or may be electrically connected to a stand-alone pacer.

[0025] The system 10 may include an ablation energy generator 50 adapted to deliver ablation energy to one or more electrodes 26 at the distal tip 28 of the catheter 14 configured for ablation. The energy generated by the ablation energy generator 50 may include, but is not limited to, radiofrequency (RF) energy or pulsed-field ablation (PFA) energy, including monopolar or bipolar high-voltage DC pulses such as may be used to produce irreversible electroporation (IRE), or a combination thereof.

[0026] PIU 30 is an interface configured to establish electrical communication between catheters, electrophysiology equipment, a power source, and a workstation 55 that controls the operation of system 10. The electrophysiology equipment of system 10 may include, for example, multiple catheters 14, location pads 25, body surface ECG electrodes 18, electrode patches 38, ablation energy generators 50, and recorder 11. Optionally and preferably, PIU 30 additionally includes processing capability for implementing real-time calculations of catheter locations and performing ECG calculations.

[0027] The workstation 55 includes a processor unit having memory, memory or storage loaded with appropriate operating software, and user interface functionality. The workstation 55 may optionally provide multiple functions, including: (1) modeling the endocardial anatomical structure in three dimensions (3D) and rendering the model or anatomical map 20 for display on the display device 27; (2) displaying activation sequences (or other data) compiled from recorded electrograms 21 on the display device 27 with representative visual indicators or images superimposed on the rendered anatomical map 20; (3) displaying the real-time location and orientation of multiple catheters within the cardiac chambers; and (5) displaying sites of interest, such as locations where ablation energy has been applied, on the display device 27. One commercially available product embodying elements of the system 10 is available as the CARTO™ 3 system, available from Biosense Webster, Inc., 31A Technology Drive, Irvine, CA 92618.

[0028] For example, system 10 may be part of a surgical system (e.g., the CARTO® system sold by Biosense Webster) configured to acquire biometric data (e.g., anatomical and electrical measurements of a patient's organs as described herein, such as heart 12) and perform cardiac ablation procedures. More particularly, the treatment of cardiac conditions, such as cardiac arrhythmias, often requires obtaining detailed mapping of cardiac tissue, chambers, veins, arteries, and / or electrical pathways. For example, as a prerequisite for successfully performing catheter ablation (as described herein), the source of the cardiac arrhythmia is accurately localized in the chambers of heart 12. Such localization may be performed by an electrophysiological study, during which spatially resolved electrical potentials are detected with a mapping catheter (e.g., catheter 14) introduced into the chambers of heart 12. This electrophysiological study, or so-called electroanatomical mapping, provides 3D mapping data that can be displayed on display device 27. Often, the mapping and therapy functions (eg, ablation) are provided by a single catheter or group of catheters, with the mapping catheter also simultaneously acting as the therapy (eg, ablation) catheter.

[0029] 2 is a block diagram of an exemplary system 100 for remotely monitoring and communicating patient biometric indicators (i.e., patient data). In the example illustrated in FIG. 2, the system 100 includes a patient biometric monitoring and processing unit 102 associated with a patient 104, a local computing device 106, a remote computing system 108, a first network 110, a patient biometric sensor 112, a processor 114, a user input (UI) sensor 116, a memory 118, a second network 120, and a transmitter-receiver (i.e., transceiver) 122.

[0030] According to one embodiment, the patient biometric monitoring and processing device 102 may be a device internal to the patient's body (e.g., subcutaneously implantable), such as the catheter 14 of Figure 1. The patient biometric monitoring and processing device 102 may be inserted into the patient via any applicable method, including oral injection, surgical insertion via a vein or artery, an endoscopic procedure, or a laparoscopic procedure.

[0031] According to one embodiment, the patient biometric monitoring and processing device 102 may be a device external to the patient, such as the electrode patch 38 of Figure 1. For example, as described in more detail below, the patient biometric monitoring and processing device 102 may include an attachable patch (e.g., attached to the patient's skin). The monitoring and processing device 102 may also include a catheter with one or more electrodes, a probe, a blood pressure cuff, a weight scale, a bracelet or smartwatch biometric tracker, a glucose monitor, a continuous positive airway pressure (CPAP) machine, or virtually any device that can provide input regarding the patient's health or biometrics.

[0032] According to one embodiment, the patient biometric monitoring and processing device 102 may include both components internal to the patient and components external to the patient.

[0033] A single patient biometric monitoring and processing device 102 is shown in Figure 2. However, an exemplary system may include multiple patient biometric monitoring and processing devices. A patient biometric monitoring and processing device may be in communication with one or more other patient biometric monitoring and processing devices. Additionally or alternatively, a patient biometric monitoring and processing device may be in communication with a network 110.

[0034] One or more patient biometric monitoring and processing devices 102 may acquire patient biometric data (e.g., electrical signals, blood pressure, body temperature, blood glucose levels, or other biometric data) and may receive at least a portion of the patient biometric data representing the acquired patient biometric indicators, as well as additional information associated with the acquired patient biometric indicators from one or more other patient biometric monitoring and processing devices 102. The additional information may be, for example, diagnostic information and / or additional information obtained from additional devices, such as wearable devices. Each patient biometric monitoring and processing device 102 may process data including its own acquired patient biometric indicators and data received from one or more other patient biometric monitoring and processing devices 102.

[0035] The biometric data (e.g., patient biometrics, patient data, or patient biometric data) may include one or more of local activation time (LAT), electrical activity, topology, bipolar mapping, baseline activity, ventricular activity, dominant frequency, impedance, etc. LAT may be a time point of threshold activity corresponding to local activation calculated based on a normalized initial starting point. Electrical activity may be any applicable electrical signal that can be measured based on one or more thresholds and may be sensed and / or enhanced based on signal-to-noise ratio and / or other filters. Topology may correspond to the physical structure of a body part or portion of a body part, or may correspond to changes in the physical structure for different parts of the body part or for different body parts. The dominant frequency may be a frequency or range of frequencies commonly found in a portion of a body part and may differ in different parts of the same body part. For example, the dominant frequency of the PVs of a heart may differ from the dominant frequency of the right atrium of the same heart. Impedance may be a resistance measurement in a given region of a body part.

[0036] Examples of biometric data include, but are not limited to, patient identification data, intracardiac electrocardiogram (IC ECG) data, bipolar intracardiac reference signals, anatomical and electrical measurements, trajectory information, body surface (BS) ECG data, historical data, brain biomarkers, blood pressure data, ultrasound signals, radio signals, audio signals, two-dimensional or three-dimensional image data, blood glucose data, and temperature data. Biometric data may generally be used to monitor, diagnose, and treat any number of various diseases, such as cardiovascular diseases (e.g., arrhythmias, cardiomyopathies, and coronary artery disease) and autoimmune diseases (e.g., type I and type II diabetes). Note that BS ECG data may include data and signals collected from electrodes on the patient's surface, IC ECG data may include data and signals collected from electrodes inside the patient's body, and ablation data may include data and signals collected from ablated tissue. Additionally, the BS ECG data, IC ECG data, and ablation data, along with catheter electrode position data, may be derived from one or more treatment records.

[0037] 2, network 110 is an example of a short-range network (e.g., a local area network (LAN) or a personal area network (PAN)). Information may be transmitted between the patient biometric monitoring and processing device 102 and the local computing device 106 over network 110 using any one of a variety of short-range wireless communication protocols, such as Bluetooth, Wi-Fi, Zigbee, Z-Wave, near field communication (NFC), ultra-wideband, Zigbee, or infrared (IR).

[0038] Network 120 may be a wired network, a wireless network, or may include one or more wired and wireless networks. For example, network 120 may be a long-range network (e.g., a wide area network (WAN), the Internet, or a cellular network). Information may be transmitted over network 120 using any one of a variety of long-range wireless communication protocols (e.g., TCP / IP, HTTP, 3G, 4G / LTE, or 5G / New Radio).

[0039] The patient biometric monitoring and processing device 102 may include patient biometric sensors 112, a processor 114, UI sensors 116, memory 118, and a transceiver 122. The patient biometric monitoring and processing device 102 may continuously or periodically monitor, store, process, and communicate any number of various patient biometric indicators over the network 110. Examples of patient biometric indicators include electrical signals (e.g., ECG signals and brain biometrics), blood pressure data, blood glucose data, and temperature data. The patient biometric indicators may be monitored and communicated to treat any number of various diseases, such as cardiovascular diseases (e.g., arrhythmias, cardiomyopathies, and coronary artery disease), and autoimmune diseases (e.g., type 1 and type 2 diabetes).

[0040] The patient biometric sensors 112 may include, for example, one or more sensors configured to sense a type of biometric patient biometric indicator. For example, the patient biometric sensors 112 may include electrodes configured to acquire electrical signals (e.g., cardiac signals, brain signals, or other bioelectrical signals), a temperature sensor, a blood pressure sensor, a blood glucose sensor, a blood oxygen sensor, a pH sensor, an accelerometer, and a microphone.

[0041] As described in more detail below, the patient biometric monitoring and processing device 102 may be an ECG monitor for monitoring an ECG signal of a heart (e.g., heart 12). The patient biometric sensor 112 of the ECG monitor may include one or more electrodes for acquiring the ECG signal. The ECG signal may be used in the treatment of various cardiovascular diseases.

[0042] In another example, the patient biometric monitoring and processing device 102 may be a continuous glucose monitor (CGM) for continuously monitoring a patient's blood glucose levels on a continuous basis to treat various diseases, such as type 1 and type 2 diabetes. The CGM may include subcutaneously placed electrodes that may monitor blood glucose levels from the patient's interstitial fluid. The CGM may be a component of a closed-loop system in which blood glucose data is sent to an insulin pump, for example, for calculated insulin delivery without user intervention.

[0043] The transceiver 122 may include a separate transmitter and receiver, or alternatively, the transceiver 122 may include a transmitter and receiver integrated into a single device.

[0044] The processor 114 may be configured to store patient data, such as patient biometric data acquired by the patient biometric sensors 112, in the memory 118 and to communicate the patient data over the network 110 via the transmitter of the transceiver 122. Data from one or more other patient biometric monitoring and processing devices 102 may also be received by the receiver of the transceiver 122, as described in more detail below.

[0045] According to one embodiment, the patient biometric monitoring and processing device 102 includes a UI sensor 116, which may be a piezoelectric or capacitive sensor configured to receive user input, such as a tap or touch. For example, the UI sensor 116 may be controlled to perform capacitive coupling in response to the patient 104 tapping or touching the surface of the patient biometric monitoring and processing device 102. Gesture recognition may be implemented by any one of a variety of capacitive types, such as resistive capacitive, surface capacitive, projected capacitive, surface ultrasonic, piezoelectric, and infrared touch. The capacitive sensor may be positioned over a small area or length of the surface such that a tap or touch on the surface activates the monitoring device.

[0046] As described in more detail below, the processor 114 may be configured to selectively respond to different tapping patterns (e.g., single tap or double tap) of a capacitive sensor, which may be the UI sensor 116, so that different tasks of the patch (e.g., data acquisition, storage, or transmission) may be initiated based on the detected pattern. In some embodiments, when a gesture is detected, audible feedback may be provided to the user from the patient biometric monitoring and processing device 102.

[0047] The local computing device 106 of the system 100 may be configured to communicate with the patient biometric monitoring and processing device 102 and act as a gateway to the remote computing system 108 via a second network 120. The local computing device 106 may be, for example, a smartphone, smartwatch, tablet, or other portable smart device configured to communicate with other devices via the network 120. Alternatively, the local computing device 106 may be a fixed or stand-alone device, such as, for example, a fixed base station including modem and / or router capabilities, a desktop or laptop computer using an executable program to communicate information between the patient biometric monitoring and processing device 102 and the remote computing system 108 via a wireless module in the PC, or a USB dongle. Patient biometric indicators may be communicated between the local computing device 106 and the patient biometric monitoring and processing device 102 via a short-range wireless network 110, such as a local area network (LAN) (e.g., a personal area network (PAN)), using short-range wireless technology standards (e.g., Bluetooth, Wi-Fi, ZigBee, Z-wave, and other short-range wireless standards). In some embodiments, the local computing device 106 may also be configured to display the acquired patient electrical signals and information associated with the acquired patient electrical signals, as described in more detail below.

[0048] In some embodiments, remote computing system 108 may be configured to receive at least one of the monitored patient's biometric indicators and information associated with the monitored patient via network 120, which is a long-range network. For example, if local computing device 106 is a cellular phone, network 120 may be a wireless cellular network, and information may be communicated between local computing device 106 and remote computing system 108 via a wireless technology standard, such as any of the wireless technologies mentioned above. As described in more detail below, remote computing system 108 may be configured to provide (e.g., visually display and / or audibly provide) at least one of the patient's biometric indicators and associated information to a medical professional (e.g., a physician).

[0049] 3 is a system diagram of an example computing environment 200 in communication with network 120. In some examples, computing environment 200 is incorporated into a public cloud computing platform (such as Amazon Web Services or Microsoft Azure), a hybrid cloud computing platform (such as HP Enterprise OneSphere), or a private cloud computing platform.

[0050] As shown in FIG. 3, computing environment 200 includes a remote computing system 108 (hereinafter computer system), which is one example of a computing system in which embodiments described herein may be implemented.

[0051] The remote computing system 108 may perform various functions via the processor 220, which may include one or more processors. Functions may include analyzing monitored patient biometrics and associated information and providing alerts, additional information, or instructions (e.g., via the display 266) according to physician-determined or algorithm-driven thresholds and parameters. As described in more detail below, the remote computing system 108 may be used to provide a patient information dashboard (e.g., via the display 266) to a medical professional (e.g., a physician), which may enable the medical professional to identify and prioritize patients with more significant needs than others.

[0052] 3, computer system 210 may include a communication mechanism, such as a bus 221, or other communication mechanism for communicating information within computer system 210. Computer system 210 further includes one or more processors 220 coupled with bus 221 for processing information. Processor 220 may include one or more CPUs, GPUs, or any other processors known in the art.

[0053] Computer system 210 also includes a system memory 230 coupled to bus 221 for storing information and instructions executed by processor 220. System memory 230 may include computer-readable storage media in the form of volatile and / or nonvolatile memory, such as read-only system memory (ROM) 231 and / or random access memory (RAM) 232. System memory RAM 232 may include other dynamic storage devices (e.g., dynamic RAM, static RAM, and synchronous DRAM). System memory ROM 231 may include other static storage devices (e.g., programmable ROM, erasable PROM, and electrically erasable PROM). Additionally, system memory 230 may be used to store temporary variables or other intermediate information during execution of instructions by processor 220. A basic input / output system (BIOS) 233 may include routines for transferring information, which may be stored in system memory ROM 231, between elements within computer system 210, such as during start-up. RAM 232 may contain data and / or program modules that are immediately accessible to and / or presently being operated on by processor 220. System memory 230 may additionally include, for example, an operating system 234, application programs 235, other program modules 236, and program data 237.

[0054] The illustrated computer system 210 also includes a disk controller 240 coupled to bus 221 for controlling one or more storage devices for storing information and instructions, such as a magnetic hard disk 241 and a removable media drive 242 (e.g., a floppy disk drive, a compact disk drive, a tape drive, and / or a solid state drive). Storage devices can be added to computer system 210 using an appropriate device interface (e.g., small computer system interface (SCSI), integrated device electronics (IDE), Universal Serial Bus (USB), or FireWire).

[0055] Computer system 210 may also include a display controller 265 coupled to bus 221 to control a monitor or display 266, such as a cathode ray tube (CRT) or liquid crystal display (LCD), for displaying information to a computer user. The illustrated computer system 210 includes a user input interface 260 and one or more input devices, such as a keyboard 262 and a pointing device 261, for interacting with a computer user and providing information to processor 220. Pointing device 261 may be, for example, a mouse, trackball, or pointing stick for communicating instructional information and command selections to processor 220 and for controlling cursor movement on display 266. Display 266 may provide a touchscreen interface that may enable input that supplements or replaces the communication of instructional information and command selections by pointing device 261 and / or keyboard 262.

[0056] Computer system 210 may perform some or each of the functions and methods described herein in response to processor 220 executing one or more sequences of one or more instructions contained in a memory, such as system memory 230. Such instructions may be read into system memory 230 from another computer-readable medium, such as hard disk 241 or removable media drive 242. Hard disk 241 may include one or more data stores and data files used by the embodiments described herein. Data store contents and data files may be encrypted for improved security. Processor 220 may also be employed in a multi-processing configuration to execute one or more sequences of instructions contained in system memory 230. In alternative embodiments, hardwired circuitry may be used in place of or in combination with software instructions. Thus, embodiments are not limited to any specific combination of hardware circuitry and software.

[0057] As mentioned above, computer system 210 may include at least one computer-readable medium or memory for retaining programmed instructions according to the embodiments described herein and for containing the data structures, tables, records, or other data described herein. As used herein, the term computer-readable medium refers to any non-transitory, tangible medium that participates in providing instructions to processor 220 for execution. Computer-readable media may take many forms, including, but not limited to, non-volatile media, volatile media, and transmission media. Non-limiting examples of non-volatile media include optical disks, solid-state drives, magnetic disks, and magneto-optical disks, such as hard disk 241 or removable media drive 242. Non-limiting examples of volatile media include dynamic memory, such as system memory 230. Non-limiting examples of transmission media include coaxial cables, copper wire, and fiber optics, including the wires that comprise bus 221. Transmission media may also take the form of acoustic or light waves, such as those generated during radio wave and infrared data communications.

[0058] The computing environment 200 may further include a computer system 210 operating in a networked environment using logical connections to the local computing device 106 and to one or more other devices, such as a personal computer (laptop or desktop), a mobile device (e.g., a patient mobile device), a server, a router, a network PC, a peer device, or other common network node, and typically includes many or all of the elements described above with respect to the computer system 210. When used in a networked environment, the computer system 210 may include a modem 272 for establishing communications over the network 120, such as the Internet. The modem 272 may be connected to the system bus 221 via a network interface 270 or another appropriate mechanism.

[0059] Network 120 as shown in FIGS. 2 and 3 may be any network or system commonly known in the art, including the Internet, an intranet, a local area network (LAN), a wide area network (WAN), a metropolitan area network (MAN), a direct connection or series of connections, a cellular telephone network, or any other network or medium capable of facilitating communication between computer system 210 and other computers (e.g., local computing device 106).

[0060] Cardiac arrhythmias, and atrial fibrillation in particular, remain common and dangerous conditions, particularly in the elderly population. In patients with normal sinus rhythm, the heart, comprised of atria, ventricles, and excitable conduction tissue, is electrically excited to beat in a synchronous, patterned manner. In patients with cardiac arrhythmias, abnormal regions of cardiac tissue do not follow the synchronous beating cycle associated with normal conduction tissue, as in patients with normal sinus rhythm. In contrast, abnormal regions of cardiac tissue conduct abnormally to adjacent tissue, disrupting the cardiac cycle and resulting in an asynchronous cardiac rhythm. Such abnormal conduction has previously been known to occur in various regions of the heart, such as the region of the sinoatrial (SA) node along the conduction pathways of the atrioventricular (AV) node and the bundle of His, or in the myocardial tissue forming the walls of the ventricles and atria.

[0061] Cardiac arrhythmias, including atrial arrhythmias, can be multiwavelet reentrant, characterized by multiple asynchronous loops of electrical impulses scattered around the atria, often self-propagating. Alternatively, or in addition to multiwavelet reentrant, cardiac arrhythmias can also have a local origin, such as when isolated regions of atrial tissue are autonomously excited in a rapid, repetitive manner. Ventricular tachycardia (V-tach or VT) is a tachycardia or fast cardiac rhythm originating from one of the ventricles. It is a potentially fatal arrhythmia because it can lead to ventricular fibrillation and sudden death.

[0062] Atrial fibrillation, a type of arrhythmia, occurs when the normal electrical impulses generated by the sinoatrial node are overwhelmed by disorganized electrical impulses originating in the atria and pulmonary veins, resulting in irregular impulses being conducted to the ventricles. This results in an irregular heartbeat that can persist for minutes to weeks, or even years. Atrial fibrillation (AF) is a chronic condition that often carries a small increased risk of death, often from stroke. Risk increases with age. Approximately 8% of people over the age of 80 have some degree of AF. While AF is often asymptomatic and generally not fatal in itself, it can lead to palpitations, weakness, fainting, chest pain, and congestive heart failure. The risk of stroke increases during AF because blood can pool in the inefficiently contracting atria and left atrial appendage, potentially forming clots. The primary treatment for AF is medication, which slows the heart rate or restores normal heart rhythm. Additionally, patients with AF are often given anticoagulants to protect them from the risk of stroke. The use of such anticoagulants carries its own risks: internal bleeding. In some patients, medication is insufficient, and their AF is deemed drug-refractory, i.e., untreatable with standard pharmacological interventions. Synchronized cardioversion can also be used to convert AF to a normal cardiac rhythm. Alternatively, AF patients are treated with catheter ablation.

[0063] Catheter ablation-based treatments can involve mapping the electrical properties of cardiac tissue, particularly the endocardium and cardiac volumes, and selectively ablating the cardiac tissue by application of energy. Cardiac mapping, for example, generating an electrical potential map (voltage map) of wave propagation along cardiac tissue, or a map of arrival times to various tissue location points (local time activation (LAT) map), can be used to detect local cardiac tissue dysfunction, and ablation, such as that based on cardiac mapping, can stop or modify the propagation of unwanted electrical signals from one part of the heart to another.

[0064] Ablation techniques disrupt unwanted electrical pathways by creating non-conducting lesions. Various energy delivery modalities have been previously disclosed for creating lesions, including the use of microwave, laser, and more commonly, radiofrequency energy to create conduction blocks along cardiac tissue walls. In a two-stage procedure, mapping followed by ablation, electrical activity at each point within the heart is typically sensed and measured by advancing a catheter containing one or more electrical sensors (or electrodes) into the heart and acquiring data at multiple points. These data are then used to select a target region of the endocardium where ablation will be performed.

[0065] Cardiac ablations and other cardiac electrophysiology procedures are becoming increasingly complex as physicians treat challenging conditions such as atrial fibrillation and ventricular tachycardia. Treatment of refractory arrhythmias currently relies on the use of three-dimensional (3D) mapping systems to reconstruct the anatomy of the cardiac chamber of interest.

[0066] For example, cardiologists rely on software such as the Complex Fractionated Atrial Electrograms (CFAE) module of the CARTO® 3 3D mapping system manufactured by Biosense Webster, Inc. (Diamond Bar, California) to analyze intracardiac EGM signals and determine ablation points for treating various cardiac disorders, including atypical atrial flutter and ventricular tachycardia.

[0067] 3D maps can provide multiple pieces of information about the electrophysiological properties of tissues, representing the anatomical and functional substrates of these challenging arrhythmias.

[0068] Cardiomyopathy of different etiologies (e.g., ischemic, dilated cardiomyopathy (DCM), hypertrophic cardiomyopathy (HCM), arrhythmogenic right ventricular dysplasia (ARVD), and left ventricular non-compaction (LVNC)) are characterized by areas of unhealthy tissue surrounded by areas of normally functioning cardiomyocytes with a distinct substrate.

[0069] 4A-4D show examples of cardiomyopathies with different etiologies. As a first example, FIGS. 4A and 4B show an exemplary rendering of a heart 400 with post-ischemic ventricular tachycardia (VT) characterized by an endocardial-epicardial low- or mid-voltage region 402 where signal conduction is slowed. This illustrates that measuring any late potentials within or around dense scar regions can help identify isthmuses that may sustain VT. The post-ischemic VT shown in FIG. 4A is characterized by an endocardial-epicardial low- or mid-voltage region where signal conduction is slowed. This illustrates that measuring any late potentials within or around dense scar regions can help identify isthmuses that may sustain VT. FIG. 4A illustrates the distribution of bipolar signal amplitude (Bi) in various sectors of the heart 400. FIG. 4A shows a Bi range of 0.5 mV to 1.5 mV. Figure 4B illustrates the distribution of Shortex Complex Intervals (SCI) in various sectors of the heart. As an example, the SCI ranges from 15.0 ms to 171.00 ms, with the SCI range of interest being 80 ms to 170 ms.

[0070] 4C and 4D show exemplary renderings of a heart 410 suffering from left ventricular non-compaction cardiomyopathy. More specifically, FIG. 4C shows an epicardial voltage map, and FIG. 4D shows a potential duration map (PDM). The three black circles in 412 in FIGS. 4C and 4D are marked as abnormal late potentials (e.g., potentials longer than 200 ms).

[0071] Abnormal tissue is generally characterized by low-voltage EGMs. However, early clinical experience with endocardial-epicardial mapping has shown that low-voltage regions are not always the sole arrhythmogenic mechanism in these patients. Indeed, low- or intermediate-voltage regions may exhibit EGM fragmentation and prolonged activity during sinus rhythm, corresponding to the isthmus at risk identified during sustained and coherent ventricular arrhythmias, e.g., only in intolerant ventricular tachycardia. Furthermore, EGM fragmentation and prolonged activity are often observed in regions exhibiting normal or near-normal voltage amplitudes (>1–1.5 mV). These latter regions can be evaluated according to voltage amplitude but are not considered normal according to the intracardiac signal and therefore represent true arrhythmogenic substrates. 3D mapping may be capable of localizing arrhythmogenic substrates on the endocardial and / or epicardial layers of the right and / or left ventricles, the distribution of which may vary depending on the primary disease progression.

[0072] Substrates related to these cardiac diseases are associated with the presence of segmented delayed EGMs in the endocardial and / or epicardial layers of the ventricular chambers (right and left). 3D mapping systems such as the CARTO® 3 are capable of localizing potential arrhythmogenic substrates of cardiomyopathies with respect to abnormal EGM detection.

[0073] Electrode catheters have been commonly used in medicine for many years. They are used to stimulate and map electrical activity in the heart and to ablate sites of abnormal electrical activity. In use, an electrode catheter is inserted into a major vein or artery, such as the femoral artery, and then guided into a chamber of the subject's heart. A typical ablation procedure involves inserting a catheter with at least one electrode at its distal end into a heart chamber. A reference electrode is typically provided by a second catheter taped to the patient's skin or positioned in or near the heart. When RF (radio frequency) current is applied to the tip electrode of the ablation catheter, the current flows toward the reference electrode and through the medium surrounding the tip electrode (i.e., blood and tissue). The current distribution is determined by the amount of electrode surface in contact with the tissue compared to blood, which has a higher conductivity than tissue. Heating of the tissue occurs due to its electrical resistance. Sufficient tissue heating induces cell destruction in the cardiac tissue, resulting in the formation of electrically non-conductive lesions within the cardiac tissue. During this process, the electrode also heats due to conduction from the heated tissue to the electrode itself. When the electrode temperature becomes high enough, possibly exceeding 60°C, a thin, transparent film of dehydrated blood proteins can form on the electrode's surface. As the temperature continues to rise, this dehydrated layer can gradually thicken, causing blood to coagulate on the electrode surface. Because dehydrated biological materials have a higher electrical resistance than endocardial tissue, the impedance to the flow of electrical energy into the tissue also increases. If the impedance becomes high enough, an impedance rise occurs, requiring the catheter to be removed from the body and the tip electrode to be cleaned.

[0074] Treatment of cardiac disorders, such as cardiac arrhythmias, often requires obtaining detailed mapping of cardiac tissue, chambers, veins, arteries, and / or electrical pathways. For example, a prerequisite for successful catheter ablation is accurate localization of the source of the cardiac arrhythmia within a cardiac chamber. Such localization can be performed by electrophysiological studies, during which spatially resolved electrical potentials are detected by a mapping catheter introduced into the cardiac chamber. This electrophysiological study, also known as electroanatomical mapping, therefore provides 3D mapping data that can be displayed on a monitor. Often, mapping and therapeutic functions (e.g., ablation) are provided by a single catheter or group of catheters; thus, the mapping catheter also simultaneously functions as a therapeutic (e.g., ablation) catheter.

[0075] Mapping cardiac regions, such as cardiac sites, tissues, veins, arteries, and / or cardiac electrical pathways, can lead to identifying problem areas, such as scar tissue, arrhythmia sources (e.g., electrical rotors), healthy regions, etc. Cardiac regions may be mapped such that a visual rendering of the mapped cardiac region is provided using a display, as further disclosed herein. Additionally, cardiac mapping may include mapping based on one or more modalities, such as, but not limited to, local activation time (LAT), electrical activity, topology, bipolar mapping, dominant frequency, or impedance. Data corresponding to multiple modalities may be captured using catheters inserted within the patient's body and provided for rendering simultaneously or at different times based on corresponding settings and / or central expert preferences.

[0076] Cardiac mapping can be performed using one or more techniques. As an example of a first technique, cardiac mapping can be performed by sensing electrical properties of cardiac tissue, such as regional activation time, as a function of precise location within the heart. The corresponding data can be acquired using one or more catheters advanced into the heart using catheters having electrical and location sensors at their distal tips. As a specific example, location and electrical activity can be initially measured at about 10 to about 20 points on the inner surface of the heart. These data points can generally be sufficient to generate a preliminary reconstruction or map of the cardiac surface with satisfactory quality. This preliminary map can be combined with data acquired at additional points to generate a more comprehensive map of the cardiac electrical activity. In clinical settings, it is not uncommon to collect data at 100 or more sites to generate a detailed and comprehensive map of the cardiac chamber's electrical activity. The detailed map can then serve as a basis for making decisions regarding therapeutic actions, such as tissue ablation, to alter the propagation of cardiac electrical activity and restore normal cardiac rhythm.

[0077] A catheter containing a position sensor can be used to determine the trajectory of each point on the heart's surface. These trajectories can be used to infer motion properties, such as the contractile force of the tissue. A map depicting such motion properties can be constructed when trajectory information is sampled at a sufficient number of points within the heart.

[0078] Electrical activity at a point within the heart can typically be measured by advancing a catheter containing an electrical sensor at or near its distal tip to the point within the heart, contacting tissue with the sensor, and acquiring data at the point. One drawback associated with mapping the chambers of the heart using a catheter containing only a single distal tip electrode is the long time required to collect data from each point relative to the necessary number of points required for a detailed map of the heart chamber as a whole. Therefore, multi-electrode catheters have been developed to simultaneously measure electrical activity at multiple points within the heart chambers.

[0079] A multi-electrode catheter may be implemented using any applicable shape, such as a linear catheter with multiple electrodes, a balloon catheter including electrodes disposed on multiple bones forming a balloon, a lasso or loop catheter with multiple electrodes, or any other applicable shape. Figure 5A shows an example of a linear catheter 502 including multiple electrodes 504, 505, and 506 that may be used to map a cardiac area. The linear catheter 502 may be fully or partially elastic so that it can twist, bend, and / or otherwise change its shape based on received signals and / or based on the application of an external force (e.g., cardiac tissue) to the linear catheter 502.

[0080] FIG. 5B shows an example of a balloon catheter 512 including multiple splines (e.g., 12 splines in the example of FIG. 5B ), including splines 514, 516, and 517, and multiple electrodes on each spline, including electrodes 521, 522, 523, 524, 525, and 526 as shown. The balloon catheter 512 can be designed so that its electrodes can be held in close contact with the endocardial surface when deployed within a patient's body. By way of example, the balloon catheter can be inserted into a lumen such as a pulmonary vein (PV). The balloon catheter can be inserted into the PV in a deflated state so that the balloon catheter does not occupy the full volume of the PV while inserted within the PV. The balloon catheter can be expanded while inside the PV, such that the electrodes on the balloon catheter contact the entire circular portion of the PV. Such contact with the entire circular portion of the PV, or any other lumen, can enable efficient mapping and / or ablation.

[0081] 5C shows an example of a loop catheter 530 (also referred to as a lasso catheter) that includes multiple electrodes 532, 534, and 536 that can be used to map a cardiac region. The loop catheter 530 can be fully or partially elastic so that it can twist, bend, and / or otherwise change its shape based on received signals and / or based on the application of an external force (e.g., cardiac tissue) on the loop catheter 530.

[0082] According to one example, a multi-electrode catheter can be advanced into a cardiac chamber. Anteroposterior (AP) and lateral fluorograms can be obtained to establish the position and orientation of each of the electrodes. Electrograms can be recorded from each of the electrodes in contact with the cardiac surface relative to a time reference, such as the onset of the P wave in sinus rhythm from a surface ECG. The system further disclosed herein can distinguish between electrodes that record electrical activity and those that do not record electrical activity due to their lack of proximity to the endocardial wall. After an initial electrogram is recorded, the catheter can be repositioned, and fluorograms and electrograms can be recorded again. An electrical map can then be constructed from a repetition of the above process.

[0083] According to one example, cardiac mapping can be generated based on the detection of intracardiac electrical fields. Non-contact methods can be implemented to simultaneously acquire large amounts of cardiac electrical information. For example, a catheter having a distal end portion can include a series of sensor electrodes distributed over its entire surface and connected to insulated conductors for connection to signal sensing and processing means. The size and shape of the end portion can be such that the electrodes are substantially spaced from the walls of the cardiac chamber. The intracardiac electrical fields can be detected during one heartbeat. According to one example, the sensor electrodes can be distributed on a series of circumferentially spaced apart planes. These planes can be perpendicular to the longitudinal axis of the catheter end. At least two additional electrodes can be provided adjacent each end of the longitudinal axis of the end. As a more specific example, the catheter can include four circumferentially spaced apart eight electrodes on each circumference. Thus, in this specific implementation, the catheter can include at least 34 electrodes (32 circumferential electrodes and two end electrodes).

[0084] According to another example, electrophysiological cardiac mapping systems and techniques based on non-contact and non-expandable multi-electrode catheters may be implemented. Electrograms may be acquired using a catheter with multiple electrodes (e.g., 42-122 electrodes). According to this implementation, knowledge of the relative geometry of the probe and endocardium may be obtained, for example, through an independent imaging modality such as transesophageal echocardiography. After independent imaging, non-contact electrodes may be used to measure cardiac surface potentials and construct a map therefrom. This technique may include (after the independent imaging step): (a) measuring potentials with multiple electrodes placed on a probe positioned within the heart; (b) determining the geometric relationship between the probe surface and the endocardium surface; (c) generating a matrix of coefficients representing the geometric relationship between the probe surface and the endocardium surface; and (d) determining the endocardium potentials based on the electrode potentials and the matrix of coefficients.

[0085] According to another example, a technique and apparatus for mapping the electrical potential distribution of a cardiac chamber may be implemented. An intracardiac multi-electrode mapping catheter assembly may be inserted into a patient's heart. The mapping catheter assembly may include a multi-electrode array with an integrated reference electrode, or preferably, a companion reference catheter. These electrodes may be deployed in the form of a substantially spherical array. The electrode array may be spatially referenced to a point on the endocardial surface by the reference electrode or by a reference catheter in contact with the endocardial surface. A preferred electrode array catheter may have a large number of individual electrode sites (e.g., at least 24). Additionally, this exemplary technique may be implemented with knowledge of the location of each of the electrode sites on the array, as well as knowledge of the cardiac geometry. These locations are preferably determined by impedance plethysmography.

[0086] According to another example, a cardiac mapping catheter assembly may include an electrode array defining multiple electrode sites. The mapping catheter assembly may also include a lumen for receiving a reference catheter having a distal tip electrode assembly that can be used to probe the heart wall. The mapping catheter may include a braid of insulated wires (e.g., having 24 to 64 wires within the braid), each of which may be used to form an electrode site. The catheter may be easily positionable within the heart for use in collecting electrical activity information from a first set of non-contact electrode sites and / or a second set of contact electrode sites.

[0087] According to another example, another catheter for mapping electrophysiological activity within the heart may be implemented. The catheter body may include a distal tip adapted to deliver stimulation pulses for pacing the heart or an ablation electrode for ablating tissue in contact with the tip. The catheter may further include at least a pair of orthogonal electrodes that generate a difference signal indicative of local cardiac electrical activity adjacent the orthogonal electrodes.

[0088] According to another embodiment, a process for measuring electrophysiological data within a heart chamber may be implemented. The method may include, in part, positioning a set of active and passive electrodes on the heart, applying a current to the active electrodes thereby generating an electric field within the heart chamber, and measuring the electric field at the passive electrode sites. The passive electrodes are included in an array positioned on an inflatable balloon of a balloon catheter. In a preferred embodiment, the array is said to have 60 to 64 electrodes.

[0089] According to another example, cardiac mapping may be performed using one or more ultrasound transducers. The ultrasound transducers may be inserted into a patient's heart and may acquire multiple ultrasound slices (e.g., two-dimensional or three-dimensional slices) at various locations and orientations within the heart. The location and orientation of a given ultrasound transducer may be known, and the acquired ultrasound slices may be stored for later display. One or more ultrasound slices corresponding to the position of a probe (e.g., a treatment catheter) may be later displayed, and the probe may be overlaid on the one or more ultrasound slices.

[0090] According to another example, a body patch and / or body surface electrodes may be positioned on or adjacent to a patient's body. A catheter having one or more electrodes may be positioned within the patient's body (e.g., within the patient's heart), and the position of the catheter may be determined by the system based on signals transmitted and received between one or more electrodes of the catheter and the body patch and / or body surface electrodes. Additionally, the catheter electrodes may sense biometric data (e.g., LAT values) from within the patient's body (e.g., within the heart). The biometric data may be associated with the determined catheter position, such that a rendering of the patient's body part (e.g., heart) may be displayed showing the biometric data as measured for each catheter position superimposed on the shape of the body part.

[0091] As discussed above, some systems may illustrate or display the results of an ablation session via a point cloud of marks or tags representing the location of each electrode during ablation across multiple sessions. FIG. 6A is an example screenshot 600 of such a point cloud generated from multiple ablation sessions, according to one or more embodiments. Each tag 602 may be variously referred to as a point, location, electrode location, mark, ablation tag, or any other similar term, and is represented in the screenshot of FIG. 6A by a red sphere or dot. In implementations using point clouds such as those shown in the example, it may be difficult for a physician to understand the effectiveness of an ablation session. For example, there is no clear indication of the ablation field energy received by the tissue. Energy from the electric field between the electrodes is not represented. There is no indication of the accumulated energy on the tissue due to repeated ablation. Additionally, there is no indication of which tags were created during the same ablation session.

[0092] In contrast, FIG. 6B is a screenshot 610 of an example volumetric trace 612 of multiple implicit functions generated from multiple ablation sessions, according to one or more embodiments. The implicit functions may include a signed distance function or other smoothing function based on the positions of adjacent electrodes during the ablation sessions, resulting in a multi-lobed region or tubular shape. In many implementations, the surface of the region may represent the area that received the same or similar amounts of energy during the ablation sessions. In some implementations, this may be determined via a signed distance function or any other similar smoothing function.

[0093] For example, referring briefly to FIG. 6C , an example of an energy field 622 around multiple electrodes 620 during an ablation session is illustrated, according to one or more embodiments. The energy field 622 is shown as concentric circles, representing an energy gradient, or equal or nearly equal amounts of energy provided during ablation at a given distance. The energy at any particular distance from the electrodes may be based on an inverse square law, which is illustrated in FIG. 6C with thinner lines the further away from each electrode 620. It may be understood that the illustration is for example purposes only, and the thickness of the lines is not to scale or proportionally represent any particular energy level; similarly, while only a few concentric circles are shown, it may be understood that the ablation energy may extend further than shown.

[0094] FIG. 6D illustrates an exemplary signed distance function 624 representing the energy field around the multiple electrodes 620 during the ablation session of FIG. 6C , according to one or more embodiments. For example, the boundaries illustrated by function 624 represent threshold distances from the left and center electrodes, and the boundaries illustrated by function 624′ represent threshold distances from the center and right electrodes, with the boundaries corresponding to the energy levels received at those distances from the electrodes. Thus, in many implementations, the boundaries may also represent points around the electrodes that recover similar or identical amounts of energy. Thus, these functions may be combined into an aggregate implicit function to represent areas that deposit the same energy during each ablation session. While shown as two-dimensional representations in FIGS. 6C and 6D , in many implementations, a three-dimensional environment may be utilized, and three-dimensional surfaces may be identified based on the implicit functions. 6C and 6D, all three electrodes are shown as "active," but in some implementations, the electrodes may be inactive (e.g., disabled, not in contact with tissue, etc.) during an ablation session. In some implementations, such inactive electrodes may be skipped during the calculation of the implicit function.

[0095] The distance to the boundary 624, 624′ (e.g., the threshold distance) may be dynamically configurable, set by a manufacturer or administrator, or otherwise changed. For example, a higher threshold would result in a thicker section between adjacent electrodes, while a lower threshold may result in a narrower section or more discontinuities. Varying this threshold may be useful to indicate different deposited energy levels in one or more ablation sessions.

[0096] As discussed above, each ablation session of the plurality of ablation sessions may be represented by an implicit function. Thus, the volumetric rendering of these sessions may be distinguished from the other sessions in many implementations. For example, FIG. 6E is a screenshot 630 of an example of volumetric tracking of the plurality of implicit functions of FIG. 6B with a highlighted implicit function 632 (indicated by a highlighted boundary) corresponding to one ablation session of the plurality of ablation sessions, according to one or more embodiments.

[0097] In some implementations, to render the volume represented by each implicit function, the system may subdivide the three-dimensional environment region into multiple voxels. In some implementations, each voxel may be associated with the nearest electrode position or the active electrode position during the ablation session. The system may calculate the implicit function and, for each voxel, determine whether the voxel is on (or, in some embodiments, within) the boundary of the volumetric surface. For example, in some implementations, the system may determine whether the distance from the voxel to the nearest neighboring electrode is within a threshold. If so, the voxel's value, which represents a unit of accumulated energy, may be incremented, modified, or adjusted according to the aggregation function. When rendering the volumetric surface for a subsequent ablation session, the voxel-related value may be similarly incremented or adjusted. The accumulation of energy over the session may, in various implementations, be used by any arbitrary function, such as the square or square root of the sum of the sessions over the voxel. For example, the aggregation function may include increasing the value representing the voxel's accumulated energy based on the distance to the electrode (or electrodes). In some implementations, the aggregation function may be based on the time of ablation during an ablation session. Thus, a higher value of a voxel is associated with a location that has accumulated energy over multiple ablation sessions, or a location that has accumulated more total energy. As shown in the example screenshot of FIG. 6E , such voxels may be shaded or colored differently (e.g., darker in the illustrated embodiment, but other shading or coloring is possible in other embodiments). In some implementations, transparency (alone or in addition to texture and / or color) may be used to represent accumulated energy, such that voxels with higher received energy may be less transparent than voxels where lower energy was received. These various implementations provide an intuitive and efficient visualization of accumulated energy over multiple ablation sessions. Combinations of the functions discussed above and / or other functions may be utilized in various implementations to provide smooth variations in surface color and / or texture.Thus, as used herein, shading may be used to refer to any distinctive visual effect, including striping, stippling, hatching, cross-hatching, transparency, specularity, reflectivity, color, or any other type of visual modifier that may provide an indication of energy deposition. Referring now to FIG. 7 , a method 700 of visualization of pulsed field ablation tags (e.g., implemented by one or more processors of a computing device) is illustrated in accordance with one or more exemplary embodiments. Method 700 addresses the need for physicians to understand the effects of one or more ablation sessions in an easy and intuitive visual manner, providing high-quality, highly efficient visualization with reduced processing resources required for high-density arrays or bitmaps.

[0098] The method begins at block 702, where one or more processors of the device may receive the positions of one or more electrodes of a catheter during an ablation session from one or more sensors. The positions may be represented in any suitable format, such as x, y, and z coordinates, spherical coordinates, an index to a voxel in an array, or any other such format. The catheter may be of any type and form, such as a linear, balloon, or loop catheter as discussed above, and may include one electrode or two or more electrodes. In various implementations, the sensors may include RF sensors, magnetic sensors, inductive sensors, or any other type and form of sensor or combination of sensors. Receiving the electrode positions may include filtering noise or other motion (e.g., due to patient inhalation), identifying periods when the electrode or catheter tip is not moving or has zero velocity, etc.

[0099] In block 703, in some implementations, one or more processors may subdivide the electrodes and / or regions into multiple clusters, and in block 704, a cluster may be selected for processing. This may be done to reduce processing requirements for each cluster, for example, because more distant electrodes may have minimal effect. In some implementations, each cluster may include a subset of multiple electrodes. In some implementations, each cluster may include a subset of voxels of the three-dimensional environment. Because the clusters are independent, they may be processed in parallel in many implementations; therefore, in some implementations, block 704 may be performed in parallel for different clusters by different processors, services, appliances, or other computing devices. In other implementations, blocks 703 and 704 may be skipped.

[0100] At block 705, in some implementations, an ablation session may be selected from multiple sessions, and at block 706, in some implementations, one or more processors may select a pair of electrodes from the multiple electrodes or select a pair of received locations (such as a pair of adjacent locations). In some implementations, the electrodes (or locations) may be selected in response to their associated locations being in the same cluster. In other implementations, the electrodes (or locations) may be selected in response to their associated locations being received from the same ablation session. In some implementations, each electrode may be associated with a semi-unique identifier or a unique identifier. Points within a region or voxel may be associated with the identifiers of electrodes that provided energy to the point or voxel during an ablation session having an amplitude or energy level above a threshold.

[0101] At block 708, in some implementations, the one or more processors may calculate an implicit function based on the positions of the selected electrode pairs. In some implementations, the implicit function may include a smoothing function. In some implementations, the implicit function may include a signed distance function. In some implementations, the function may be further based on a predetermined threshold.

[0102] In some implementations, blocks 706-708 may be repeated iteratively if additional electrodes are present. For example, in some implementations, the system may calculate a function for the first and second electrodes or locations, then select a third electrode location and calculate a function for a combination of the first and second electrodes or locations (e.g., the previously calculated function) and the newly selected electrode or location, thus iteratively constructing an aggregate function for all three electrodes or locations. In other implementations, blocks 706-708 may be repeated successively with pairs of electrodes or locations (e.g., calculate a distance function for the first and second electrodes or locations, then calculate a distance function for the second electrode or location and the third electrode or location, etc.). In such implementations, the system may avoid calculating the energy contributed by the second electrode to any particular voxel twice. For example, as discussed above, in some implementations, a value associated with each voxel in a cluster may be incremented in response to the voxel's location being within or on the boundary of the signed distance function for the first and second electrodes or locations. In some such implementations, when determining the effects of a second electrode or location and a newly selected third electrode or location, any voxel whose associated value has been incremented may not have its value incremented again. Stated another way, in such implementations, during calculation of the effect of any ablation session, the value associated with a voxel may be incremented only once, regardless of whether the effects of many neighboring electrodes are applied. In other implementations, such as when constructing aggregated functions as discussed above, the value associated with a voxel may be incremented multiple times.

[0103] In many implementations, blocks 705-708 may be repeated for additional ablation sessions. While shown repeating before block 710, in some implementations, blocks 705-710 may be repeated (e.g., a loop may occur after the first instance of block 710, and block 710 may be repeated for each additional session). Similarly, in many implementations, blocks 704-708 may be repeated for additional clusters of electrode locations in the environment. In many implementations, blocks 704-708 may be performed in parallel for different clusters by separate processors, services, or devices.

[0104] In block 710, a volumetric representation of the computed implicit function (or functions of multiple ablation sessions) may be rendered. As discussed above, in many implementations, the system may determine a value associated with each voxel in the cluster or three-dimensional environment, which is incremented in response to the voxel being within (or, in various implementations, on the boundary of) a pair of adjacent electrodes or corresponding locations. In some implementations, a unique or semi-unique identifier of the electrode associated with the corresponding boundary may be stored with or associated with the voxel, which, in various implementations, may be in addition to or instead of an energy value or other counter. For example, in response to determining that a voxel is within (or on) a boundary according to a signed distance function or other smooth function, an identifier of the associated electrode may be stored in association with the voxel such that the voxel includes or is associated with a set of identifiers of electrodes and their locations during the ablation session. This allows the system to calculate the distance to the boundary at runtime with high visual fidelity without having to store additional data regarding the boundary surface. In some implementations, the system may shade, color, visualize, or otherwise highlight or indicate each voxel with the incremented value to display the volumetric representation. In other implementations, the representation may be rendered via ray tracing using the boundary of the implicit function as a reflective surface. Other implementations of rendering may be utilized as needed. The volumetric representation may be rendered to a display such as a monitor, a stereoscopic display (e.g., a virtual reality or augmented reality display or glasses), a volumetric display, a holographic display, a pseudo-3D display (e.g., a 2D display with head tracking and rendering of a pseudo-3D environment), or any other suitable display.

[0105] Thus, embodiments of the systems and methods discussed herein provide an intuitive and easily understandable visualization of the effects of one or more ablation sessions on tissue with reduced processing or resource consumption relative to array-based implementations through the use of implicit functions, particularly signed distance functions calculated based on the positions of adjacent electrodes of the catheter during ablation.

[0106] While features and elements have been described above in particular combinations, those skilled in the art will understand that each feature or element can be used alone or in combination with other features and elements. In addition, the methods described herein may be implemented in a computer program, software, or firmware embodied in a computer-readable medium for execution on a computer or processor. Examples of computer-readable media include electronic signals (transmitted via wired or wireless connections) and computer-readable storage media. Examples of computer-readable storage media include, but are not limited to, read-only memory (ROM), random-access memory (RAM), registers, 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). A processor in association with software may be used to implement a radio frequency transceiver for use in a WTRU, UE, terminal, base station, RNC, or any host computer.

[0107] The flowcharts and block diagrams in the figures illustrate the structure, functionality, and operation of possible implementations of systems, methods, and computer program products according to various embodiments of the present invention. In this regard, each block in a flowchart or block diagram may represent a module, segment, or portion of instructions, including one or more executable instructions for implementing the depicted logical function(s). In some alternative implementations, the functions shown in the blocks may occur out of the order shown in the figures. For example, two blocks shown in succession may, in fact, be executed substantially concurrently, or the blocks may sometimes be executed in the reverse order, depending on the functionality involved. It should also be noted that each block of the block diagrams and / or flowchart illustrations, and combinations of blocks in the block diagrams and / or flowchart illustrations, may be implemented by a dedicated hardware-based system that performs the specified functions or operations, or may operate or be executed by a combination of dedicated hardware and computer instructions.

[0108] While features and elements have been described above in particular combinations, those skilled in the art will understand that each feature or element can be used alone or in combination with other features and elements. Additionally, the methods described herein can be implemented in a computer program, software, or firmware embodied in a computer-readable medium for execution on a computer or processor. As used herein, computer-readable medium should not be construed as a signal that is itself ephemeral, such as an electric wave or other freely propagating electromagnetic wave, an electromagnetic wave propagating through a waveguide or other transmission medium (e.g., a light pulse passing through a fiber optic cable), or an electrical signal transmitted through a current line.

[0109] Examples of computer-readable media include electrical signals (transmitted via wired or wireless connections) and computer-readable storage media. Examples of computer-readable storage media include, but are not limited to, registers, cache memory, semiconductor memory devices, magnetic media such as internal hard disks and removable disks, magneto-optical media, optical media such as compact disks (CDs) and digital versatile disks (DVDs), random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), static random access memory (SRAM), and memory sticks. A processor may be used with software to implement a radio frequency transceiver for use in a terminal, a base station, or any host computer.

[0110] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting. As used herein, the singular forms "a," "an," and "the" are intended to include the plural unless the context clearly dictates otherwise. It is further understood that the terms "comprise" and / or "comprising," when used herein, indicate the presence of stated features, integers, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or other features, integers, steps, operations, elements, components, and / or groups thereof.

[0111] The descriptions of different embodiments herein are presented for illustrative purposes, but are not intended to be exhaustive or limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terms used herein are selected to best explain the principles, practical applications, or technical improvements of the embodiments compared to technologies found on the market, or to enable those skilled in the art to understand the embodiments disclosed herein.

[0112] [Embodiment] (1) A system for visualization of pulsed field ablation tags, comprising: a device comprising: a processor in communication with one or more sensors; and a catheter comprising a plurality of electrodes; the processor: receiving, via the one or more sensors, a position of each of the plurality of electrodes within a three-dimensional environment during a first ablation session; calculating, for the first ablation session, a first implicit function representing an energy field of the first ablation session from the received positions of each of the plurality of electrodes; and presenting, via a display, a first volumetric representation of the calculated first implicit function. (2) The system of embodiment 1, wherein the processor is further configured to calculate the first implicit function via a signed distance function based on positions of a pair of adjacent electrodes among the plurality of electrodes during the first ablation session. (3) The system of embodiment 2, wherein the processor is further configured to calculate the implicit function via a plurality of signed distance functions, each of the plurality of signed distance functions corresponding to a different pair of adjacent electrodes. (4) The system of embodiment 1, wherein each electrode of the plurality of electrodes is associated with a unique identifier, and the processor is further configured to determine, for each voxel of the plurality of voxels of the three-dimensional environment, one or more identifiers of electrodes that provided energy to a position corresponding to the voxel during the first ablation session. (5) The system of embodiment 1, wherein the processor is further configured to calculate, for each of a plurality of voxels of the three-dimensional environment, a distance from the voxel to the position of one of the plurality of electrodes.

[0113] (6) The system of embodiment 5, wherein the processor is further configured to determine, for each of the plurality of voxels of the three-dimensional environment, whether the corresponding calculated distance is less than a threshold. (7) The system of embodiment 6, wherein the processor is further configured to modify a value associated with one or more of the plurality of voxels of the three-dimensional environment in response to the corresponding calculated distance being less than the threshold. (8) The system of embodiment 6, wherein the processor is further configured to modify a value associated with a first voxel in response to the distance from the first voxel to a position of one of the plurality of electrodes during the first ablation session being less than the threshold, and to modify the value associated with the first voxel in response to the distance from the first voxel to a position of one of the plurality of electrodes during a second ablation session being less than the threshold. (9) The system of embodiment 6, wherein the processor is further configured to present the first volumetric representation as one or more voxels within the three-dimensional environment, each voxel being shaded based on the value associated with the voxel. (10) The processor: receiving, via the one or more sensors, a position of each of the plurality of electrodes during a second ablation session; For the second ablation session, calculate a second implicit function representing the energy field of the second ablation session; 10. The system of claim 9, further configured to present, via the display, a second volumetric representation of the calculated second implicit function together with the first volumetric representation of the calculated first implicit function.

[0114] (11) The processor: classifying the positions of each of the plurality of electrodes during the first ablation session into a plurality of clusters; 2. The system of claim 1, further configured to calculate the first implicit function for the first ablation session via a signed distance function between electrode pairs in each cluster. (12) A method for visualization of pulsed field ablation tags, comprising: receiving, by a processor of the device, from one or more sensors, a position within the three-dimensional environment of each of a plurality of electrodes of the catheter during a first ablation session; calculating, by the processor, for the first ablation session, a first implicit function representing an energy field of the first ablation session from the received positions of each of the plurality of electrodes; and presenting, by the processor via a display, a first volumetric representation of the calculated first implicit function. (13) The method of embodiment 12, further comprising calculating the first implicit function via a signed distance function based on positions of a pair of adjacent electrodes of the plurality of electrodes during the first ablation session. (14) The method of embodiment 13, further comprising calculating the implicit function via a plurality of signed distance functions, each of the plurality of signed distance functions corresponding to a different pair of adjacent electrodes. (15) The method of embodiment 12, wherein each electrode of the plurality of electrodes is associated with a unique identifier, and further comprising, for each voxel of a plurality of voxels of the three-dimensional environment, determining one or more identifiers of electrodes that provided energy to a position corresponding to the voxel during the first ablation session.

[0115] (16) The method of embodiment 12, further comprising calculating, for each of a plurality of voxels of the three-dimensional environment, a distance from the voxel to a position of one of the plurality of electrodes. (17) The method of embodiment 16, further comprising determining, for each of the plurality of voxels of the three-dimensional environment, whether the corresponding calculated distance is less than a threshold. (18) The method of embodiment 17, further comprising, for one or more voxels of the plurality of voxels of the three-dimensional environment, modifying a value associated with the voxel in response to the corresponding calculated distance being less than the threshold. (19) The method of embodiment 17, further comprising: modifying a value associated with a first voxel in response to the distance from the first voxel to a location of one of the plurality of electrodes during the first ablation session being less than the threshold; and modifying the value associated with the first voxel in response to the distance from the first voxel to a location of one of the plurality of electrodes during a second ablation session being less than the threshold. (20) The method of embodiment 17, further comprising presenting the first volumetric representation as one or more voxels within the three-dimensional environment by the processor, each voxel being shaded based on the value associated with the voxel.

[0116] (21) receiving, via the one or more sensors, a position of each of the plurality of electrodes during a second ablation session; and calculating, for the second ablation session, a second implicit function representing an energy field of the second ablation session; 21. The method of claim 20, further comprising: presenting, via the display, a second volumetric representation of the calculated second implicit function together with the first volumetric representation of the calculated first implicit function. (22) classifying the positions of each of the plurality of electrodes during the first ablation session into a plurality of clusters; 13. The method of embodiment 12, further comprising: calculating the first implicit function for the first ablation session via a signed distance function between electrode pairs in each cluster.

Claims

1. 1. A system for visualization of pulsed field ablation tags, comprising: a device comprising: a processor in communication with one or more sensors; and a catheter comprising a plurality of electrodes; the processor: receiving, via the one or more sensors, a position of each of the plurality of electrodes within a three-dimensional environment during a first ablation session; calculating, for the first ablation session, a first implicit function representing an energy field of the first ablation session from the received positions of each of the plurality of electrodes; and presenting, via a display, a first volumetric representation of the calculated first implicit function.

2. 2. The system of claim 1, wherein the processor is further configured to calculate the first implicit function based on positions of a pair of adjacent electrodes of the plurality of electrodes during the first ablation session via a signed distance function.

3. 3. The system of claim 2, wherein the processor is further configured to calculate the implicit function via a plurality of signed distance functions, each of the plurality of signed distance functions corresponding to a different pair of adjacent electrodes.

4. 2. The system of claim 1, wherein each electrode of the plurality of electrodes is associated with a unique identifier, and the processor is further configured to determine, for each voxel of a plurality of voxels of the three-dimensional environment, one or more identifiers of electrodes that provided energy to a position corresponding to the voxel during the first ablation session.

5. The system of claim 1 , wherein the processor is further configured to calculate, for each of a plurality of voxels of the three-dimensional environment, a distance from the voxel to a location of one of the plurality of electrodes.

6. The system of claim 5 , wherein the processor is further configured to determine, for each of the plurality of voxels of the three-dimensional environment, whether the corresponding calculated distance is less than a threshold value.

7. 7. The system of claim 6, wherein the processor is further configured to modify a value associated with one or more of the plurality of voxels of the three-dimensional environment in response to the corresponding calculated distance being less than the threshold.

8. 7. The system of claim 6, wherein the processor is further configured to modify a value associated with a first voxel in response to the distance from the first voxel to a location of one of the plurality of electrodes during the first ablation session being less than the threshold, and to modify the value associated with the first voxel in response to the distance from the first voxel to a location of one of the plurality of electrodes during a second ablation session being less than the threshold.

9. 7. The system of claim 6, wherein the processor is further configured to present the first volumetric representation as one or more voxels within the three-dimensional environment, each voxel being shaded based on the value associated with the voxel.

10. the processor: receiving, via the one or more sensors, a position of each of the plurality of electrodes during a second ablation session; for the second ablation session, calculating a second implicit function representing the energy field of the second ablation session; 10. The system of claim 9, further configured to present via the display a second volumetric representation of the calculated second implicit function along with the first volumetric representation of the calculated first implicit function.

11. the processor: classifying the positions of each of the plurality of electrodes during the first ablation session into a plurality of clusters; 10. The system of claim 1, further configured to calculate the first implicit function for the first ablation session via a signed distance function between electrode pairs within each cluster.

12. 1. A method for visualization of pulsed field ablation tags, comprising: receiving, by a processor of the device, from one or more sensors, a position within the three-dimensional environment of each of a plurality of electrodes of the catheter during a first ablation session; calculating, by the processor, for the first ablation session from the received positions of each of the plurality of electrodes, a first implicit function representing an energy field of the first ablation session; presenting, by the processor via a display, a first volumetric representation of the calculated first implicit function.

13. 13. The method of claim 12, further comprising calculating the first implicit function based on positions of a pair of adjacent electrodes of the plurality of electrodes during the first ablation session via a signed distance function.

14. The method of claim 13 , further comprising calculating the implicit function via a plurality of signed distance functions, each of the plurality of signed distance functions corresponding to a different pair of adjacent electrodes.

15. 13. The method of claim 12, wherein each electrode of the plurality of electrodes is associated with a unique identifier, and further comprising, for each voxel of a plurality of voxels of the three-dimensional environment, determining one or more identifiers of electrodes that provided energy to a location corresponding to the voxel during the first ablation session.

16. The method of claim 12 , further comprising: for each of a plurality of voxels of the three-dimensional environment, calculating a distance from the voxel to a location of one of the plurality of electrodes.

17. The method of claim 16 , further comprising: for each of the plurality of voxels of the three-dimensional environment, determining whether the corresponding calculated distance is less than a threshold value.

18. 18. The method of claim 17, further comprising, for one or more voxels of the plurality of voxels of the three-dimensional environment, modifying a value associated with the voxel in response to the corresponding calculated distance being less than the threshold.

19. 18. The method of claim 17, further comprising: modifying a value associated with a first voxel in response to the distance from the first voxel to a location of one of the plurality of electrodes during the first ablation session being less than the threshold; and modifying the value associated with the first voxel in response to the distance from the first voxel to a location of one of the plurality of electrodes during a second ablation session being less than the threshold.

20. 18. The method of claim 17, further comprising presenting, by the processor, the first volumetric representation as one or more voxels within the three-dimensional environment, each voxel shaded based on the value associated with the voxel.

21. receiving, via the one or more sensors, a position of each of the plurality of electrodes during a second ablation session; calculating, for the second ablation session, a second implicit function representing an energy field of the second ablation session; 21. The method of claim 20, further comprising presenting via the display a second volumetric representation of the calculated second implicit function along with the first volumetric representation of the calculated first implicit function.

22. classifying the positions of each of the plurality of electrodes during the first ablation session into a plurality of clusters; 13. The method of claim 12, further comprising: calculating the first implicit function for the first ablation session via a signed distance function between electrode pairs within each cluster.

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