Point of Interest (POI) Maps for Cardiac Arrhythmia Diagnosis

Abstract

The system includes a display and a processor configured to receive a cardiac anatomical surface, receive a plurality of electrophysiological (EP) data points, each of which includes (i) a respective location on the cardiac anatomical surface and (ii) a respective value of an EP parameter indicative of arrhythmia at the location, and apply respective criteria to the values ​​of the EP data points. For each EP data point whose value meets the respective criteria, the processor is configured to graphically encode the EP data point to generate a point of interest (POI), overlay the POIs of at least two types of EP parameters indicative of arrhythmia on the anatomical surface to generate a POI map reflecting surface locations that are likely to be arrhythmogenic, and visualize the POI map to a user on the display.

Description

[Technical Field]

[0001] FIELD OF THE DISCLOSURE The present disclosure relates generally to cardiac electrophysiological (EP) mapping, and more particularly to cardiac EP maps. [Background technology]

[0002] EP maps generated from catheter-acquired EP signals have been previously described in the patent literature. For example, U.S. Patent Application Publication No. 2022 / 0211314 describes a method that includes receiving (i) a modeled surface of at least a portion of a heart and (ii) a plurality of EP values ​​measured at a plurality of respective locations within the heart. A plurality of regions are defined on the modeled surface, and for each region, a confidence level for EP values ​​whose locations fall within the region is estimated. The modeled surface is presented to a user, including (i) the EP values ​​overlaid on the modeled surface and (ii) a graphically visualized confidence level within each region of the modeled surface.

[0003] As another example, U.S. Patent No. 11,160,485 describes a method including storing an anatomical map of at least a portion of a cardiac surface. Respective electrogram (EGM) signal amplitudes measured at respective locations on the cardiac surface are stored. Based on the EGM signal amplitudes, one or more first regions of the surface in which the EGM signal amplitudes are subdivided and one or more second regions of the surface in which the EGM signal amplitudes are not subdivided are defined. A first surface representation of the subdivided EGM signal amplitudes in the first regions is generated. Propagation times are extracted from the unsubdivided EGM signal amplitudes in the second regions, and a second surface representation of the propagation times is derived. The first and second surface representations of the respective first and second regions of the surface are simultaneously presented, superimposed on the anatomical map.

[0004] In their paper titled "Atrial Fibrillation (AF) Ablation Guided by Spatiotemporal Electrogram Dispersion Without Pulmonary Vein Isolation" (JACC, Vol. 69, No. 3, (2017)), Julien S. et al. describe a method for identifying AF drivers using EP mapping clustering of intracardiac electrograms that show spatiotemporal dispersion.

[0005] The present disclosure will be more fully understood from the following detailed description of the embodiments thereof, taken in conjunction with the drawings in which: [Brief explanation of the drawings]

[0006] [Figure 1] FIG. 1 is a schematic, pictorial illustration of a catheter-based system for electrophysiological (EP) mapping and ablation, according to one embodiment of the present disclosure. [Figure 2] FIG. 1 is a schematic diagram of a Point of Interest (POI) map according to one embodiment of the present disclosure. [Figure 3] FIG. 10 is a schematic diagram of a POI map according to another embodiment of the present disclosure. [Figure 4] 1 is a flowchart that schematically illustrates a method for generating, editing, and presenting a POI map, according to one embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0007] overview Probe-based (e.g., multi-electrode catheter-based) cardiac diagnostic and therapeutic systems can measure numerous intracardiac electrophysiological (EP) signals, such as electrograms (EGMs), during invasive procedures. Analysis of such vast amounts of EP information is typically facilitated by generating and presenting one or more EP maps to a user (e.g., a physician or clinical application specialist). Each such EP map can display typical EP parameters for the procedure. Examples of EP parameters that can be presented include EP parameters indicative of arrhythmias selected from a list including cycle length, local ripple percentage, local activation time (LAT), bipolar potential, excitation wave velocity, and complex fractionated atrial electrograms (CFAE).

[0008] Physicians diagnosing and / or planning treatment for cardiac arrhythmias typically view multiple different EP maps to examine various cardiac tissue characteristics. Thus, diagnosis and planning (e.g., selecting ablation locations to eliminate arrhythmias) are typically based on mentally assembling information from multiple EP maps, each displaying one or more of the aforementioned EP parameters. Physicians viewing multiple different EP maps can become lost in the details, confusing the display, and therefore failing to prioritize tissue locations for treatment.

[0009] The examples of the present disclosure described herein provide algorithms and visualizations for high-level and fully automated acquisition and / or selection of EP data points for display.

[0010] In some examples, a user or processor sets acquisition criteria and acquires only data points that meet these criteria for use in analysis, such as stability of acquisition for a minimum predetermined duration (e.g., 2.5 seconds) for a minimum predetermined number of electrodes of a multi-electrode catheter (e.g., a group of electrodes that covers a minimum contiguous tissue area at a time).

[0011] The disclosed technology uses a GUI to select several types of EP parameters and their respective criteria to be applied to acquired data points. Using the EP selection, a processor analyzes and displays point-of-interest (POI) maps, as described below. Using one or more of the disclosed POI maps, a physician may overcome, for example, the aforementioned difficulties in prioritizing tissue locations for ablation.

[0012] In some examples, the processor displays an anatomical map overlaid with graphically encoded (e.g., flagged) POIs. To this end, the processor receives a plurality of EP data points, each including a respective location on a cardiac anatomical surface and a respective value of an EP parameter indicative of an arrhythmia at that location.

[0013] The processor applies each criterion to the values ​​of the EP data points, and for each EP data point whose value meets the respective criterion, the processor graphically encodes the EP data point to generate a point of interest (POI).

[0014] The processor overlays POIs of at least two types of EP parameters indicative of arrhythmia onto an anatomical surface to generate a POI map reflecting surface locations that are likely to be arrhythmogenic, and visualizes the POI map to a user on a display.

[0015] In one example, to reflect surface locations that are likely to be arrhythmogenic, the processor divides the cardiac anatomical surface into unit areas of a predetermined size and shape, determines the count of differently coded POIs within each unit area or a given portion of a unit area, and graphically displays the count in the unit area.

[0016] The graphical display (e.g., flags) may be shaped and / or color-coded to indicate the EP parameter they represent. The disclosed POI maps do not show the values ​​of each EP parameter, but only the locations within the anatomical map where the EP parameter values ​​meet the criteria. Using the disclosed POI maps, tissues exhibiting arrhythmogenic behavior may be flagged with multiple flags or with a special flag indicating multiple flags.

[0017] The flags may be pins or color mosaics on the anatomical map. The graphical representation may be embedded in the surface itself, e.g., a wavefront displayed using a continuous color code, as is done in coherent EP maps and spatiotemporal dispersion maps. The anatomical map may be a modeled map (Fast Anatomical Map, FAM) or a 3D image of a portion of the heart.

[0018] In this way, the physician can obtain an overview of the POIs on the anatomical map. As described above, the processor may divide the anatomical map into unit areas of a predetermined size and shape, and in each unit area, generate a composite flag representing multiple flags therein from different flags of different EP parameters. For example, if the flags are stripes of different colors, the processor may generate a complex stripe pattern representing the different colors.

[0019] In one example of a POI map, the processor displays an EP map, such as a spatiotemporal dispersion map (over 85% (70-90%) of consecutive bipolar sequential activations of a multi-electrode catheter have a maximum derivative above a defined threshold of atrial fibrillation cycle length), in which the processor adds color-coded pins that protrude to indicate additional parameters of interest for arrhythmia. Specifically, the processor may in this manner generate a POI map of atrial fibrillation (AFib) that assists physicians in determining where to ablate tissue. The user can modify the height and / or width of the pins depending on the criteria selected for the pins to represent.

[0020] An exemplary scheme for color-coding the protruding pins is as follows: For example, a red pin for a position with a regularity of the period length defined as a point within the range of [minimum period length, minimum period length + 10ms] For example, blue pins for locations with regularity of STD period length defined as points with STD within the range of [minimum STD period length, minimum STD period length + 5 ms] Brown pins for locations with points that have CFAE (indicating subdivision signals) Purple pin for location with local ripple percentage 0.75 * Purple pins appear at points exceeding the maximum local ripple percentage

[0021] In another example, a POI map is provided to the physician along with a color scale that classifies regions within it according to the number of parameters that indicate arrhythmia. The physician can select from a list of parameters to be used to construct the map. For example, the physician can select five parameters. A scale on the map indicates the number of these selected parameters, ranging from 0 to 5, that affect a given region of the map. The physician can consider regions that show a 5 to be candidates for ablation.

[0022] The physician can select different EP parameters from a list that will be counted in the EP parameter scale. Additionally, the physician can assign weights to the parameters.

[0023] Finally, the processor is used in training a machine learning model with a sufficient number of POI maps to build an expert application capable of generating one or more optimized POI maps.

[0024] System Description FIG. 1 is a schematic, pictorial illustration of a catheter-based electrophysiological (EP) mapping and ablation system 10, according to one embodiment of the present disclosure.

[0025] The system 10 may include multiple catheters that are percutaneously inserted by a physician 24 through the patient's vascular system and into the cavities or vascular structures of the heart 12. In the illustrated example, a delivery sheath catheter is inserted into the left or right atrium near a desired location within the heart 12. Multiple catheters may then be inserted into the delivery sheath catheter to reach the desired location. The multiple catheters 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 EP mapping catheter 14 configured to sense IEGMs is illustrated herein. The physician 24 contacts a distal tip 28 (hereinafter also referred to herein as a “distal end assembly 28”) of the catheter 14 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.

[0026] 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 position 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.

[0027] The magnetic-based position sensor 29 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 magnetic-based position 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.

[0028] System 10 includes one or more electrode patches 38 positioned for skin contact with patient 23 to establish a position reference for location pads 25, as well as impedance-based tracking of electrodes 26. For impedance-based tracking, current is directed to electrodes 26 and sensed at electrode skin patches 38, allowing the position of each electrode to be triangulated via electrode patches 38. Details of impedance-based position tracking techniques are described in U.S. Patent Nos. 7,536,218, 7,756,576, 7,848,787, 7,869,865, and 8,456,182.

[0029] Recorder 11 displays electrograms 21 captured by body surface ECG electrodes 18 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.

[0030] The system 10 may include an ablation energy generator 50 adapted to deliver ablation energy to one or more electrodes at the distal tip of a catheter 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 unipolar or bipolar high-voltage DC pulses, such as may be used to effect irreversible electroporation (IRE), or a combination thereof.

[0031] The Patient Interface Unit (PIU) 30 is an interface configured to establish electrical communication between the catheters, electrophysiology equipment, a power source, and a workstation 55 that controls the operation of the system 10. The electrophysiology equipment of the system 10 may include, for example, multiple catheters, location pads 25, body surface ECG electrodes 18, electrode patches 38, an ablation energy generator 50, and a recorder 11. Optionally and preferably, the PIU 30 additionally includes processing capabilities for performing real-time catheter position calculations and ECG calculations.

[0032] The workstation 55 includes a processor unit 56 having a memory 57, a memory or storage device having appropriate operating software loaded therein, and user interface functionality. The workstation 55 may optionally provide multiple functions, including: (1) modeling the endocardial anatomy in three dimensions (3D) and rendering the model or POI map 20 for display on the display device 27; (2) displaying activation sequences (or other data) compiled from recorded electrograms 21 with representative visual indicia or images included in the rendered POI map 20 on the display device 27; (3) displaying the real-time positions and orientations of multiple catheters within the cardiac chambers; and (4) 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, California 92618.

[0033] Point of Interest (POI) Cardiac Map 2 is a schematic diagram of a POI map 200 according to one embodiment of the present disclosure. The POI map 200 may be the POI map 20 shown displayed in FIG.

[0034] The POI map 200 includes an anatomical map 202, in this case of the left atrium. The POI map 200 further includes graphically coded (e.g., flagged) EP data points. The data POIs are for a given unit area on the map overlaid with at least two EP parameters. The flags may be graphically shaped and / or color-coded to indicate the parameters they represent. The disclosed POI map does not indicate the values ​​of each of the EP parameters, but only the locations in the anatomical map where the EP parameter values ​​exceed a threshold value.

[0035] In the illustrated example of POI map 200, the processor displays a raised color-coded pin indicating an additional parameter of interest for arrhythmias, such as atrial fibrillation (AFib).

[0036] Examples of color-coding schemes for projecting pins include: For example, a red pin 204 for a position having a regularity of a period length defined as a point within the range of [minimum period length, minimum period length + 10 ms] For example, blue pin 206 for a position with regularity of STD period length defined as a point with STD within the range of [minimum STD period length, minimum STD period length + 5 ms] Brown pin 208 for locations with points having CFAE (indicating subdivision signals) Purple pin 210, the location with the local ripple percentage, is 0.75 * Appears at points exceeding the maximum local ripple percentage

[0037] As can further be seen, pin 212 includes a different colored ring to mark the location where the indicia of pins 204, 206, and 208 overlap one another.

[0038] The EP wavefront may be color-coded on the map (214), for example, as is done in coherent EP maps.

[0039] One or more regions on the EP map can be graphically encoded if analysis indicates that the region exhibits spatiotemporal variance above a given gradient. (215) If a sufficient number of electrodes are under test for a sufficient duration, such variance can be determined.

[0040] Finally, additional indicators may be included, such as balls 216 to indicate point potential durations (PM) that exceed a defined threshold.

[0041] 3 is a schematic diagram of a POI map 300 according to another embodiment of the present disclosure. The POI map 300 may be the POI map 20 shown displayed in FIG. 1. The POI map 300 includes an anatomical map 302, which in the illustrated case is of the left atrium.

[0042] The POI map 300 is provided to the physician along with a color scale that classifies regions according to the number of EP parameters indicative of arrhythmia. The physician can select from a list 304 of EP parameters to be used to construct the POI map 300. For example, the physician can select five EP parameters from the list of EP parameters indicative of arrhythmia, such as the aforementioned cycle length, regional ripple percentage, regional activation time (LAT), bipolar potential, excitation wave velocity, spatiotemporal dispersion gradient, and complex fractional atrial potential (CFAE). A scale 306 on the map indicates the number of these selected EP parameters, ranging from 0 to 5, affecting a given region of the map. The physician can consider a region 308 showing a 5 to be a candidate for ablation.

[0043] The physician can select different EP parameters from a list 304 to be counted in the EP parameter scale 306. Additionally, the physician can assign weights to the EP parameters.

[0044] 4 is a flow chart that schematically illustrates a method for generating, editing, and presenting POI maps, such as maps 200 and 300, according to one embodiment of the present disclosure. The algorithm executes a process that, according to the presented example, begins with processor 28 receiving (e.g., uploading) cardiac anatomical surfaces, such as anatomical maps 202 and 302, in anatomical surface upload step 402.

[0045] Next, the processor receives a plurality of EP data points on the anatomical surface, each of which corresponds to (belongs to) one of several EP parameters, in an EP data point receiving step 404 .

[0046] In a criteria application step 406, the processor applies respective EP criteria (i.e., for each EP parameter) to the EP data points. These may include EP values ​​that exceed or fall within a threshold range. The EP parameters may be obtained from the aforementioned arrhythmia-indicative EP parameters: cycle length, local ripple percentage, local activation time (LAT), bipolar potential, excitation wave velocity, spatiotemporal dispersion gradient, and complex fractionated atrial potential (CFAE).

[0047] In a graphics step 408, the processor graphically encodes each EP data that meets the criteria to generate an interest point.

[0048] In a POI map generation step 410, the processor graphically depicts POIs at locations where at least two or more of the EP parameters meet their respective predetermined criteria (e.g., as seen at pins 212 in FIG. 2), and / or according to a scale that determines a count of differentially coded POIs therein (e.g., up to 5 as seen at scale 306 in FIG. 3), and graphically depicts the count in a unit area. In this manner, the processor has a POI map that provides an indication of surface locations that are likely to be arrhythmogenic.

[0049] Finally, the processor displays the POI map to the user, such as by displaying map 20 on display device 27, in a POI map display step 412. [Example]

[0050] Example 1 The system (10) includes a display (27) and a processor (56). The processor is configured to receive a cardiac anatomical surface (202, 302), receive a plurality of electrophysiological (EP) data points including (i) respective locations on the cardiac anatomical surface and (ii) respective values ​​of EP parameters indicative of arrhythmia at the locations, and apply respective criteria to the values ​​of the EP data points. For each EP data point whose value meets the respective criteria, the processor is configured to graphically encode (204, 206, 208, 210, 212) the EP data point to generate points of interest (POIs), overlay the POIs of at least two types of EP parameters indicative of arrhythmia on the anatomical surface to generate a POI map reflecting surface locations that are likely to be arrhythmogenic, and visualize the POI map to a user on the display (27).

[0051] Example 2 2. The system (10) of Example 1, wherein the EP parameter indicative of arrhythmia is of a type selected from a list including at least two of cycle length, local ripple percentage, local activation time (LAT), bipolar potential, excitation wave velocity, spatiotemporal dispersion gradient, and complex fractionated atrial potential (CFAE).

[0052] Example 3 The system (10) of any of Examples 1 and 2, wherein the processor (56) is configured to visualize the POI map by dividing the cardiac anatomical surface (202, 302) into unit areas of a predetermined size and shape, determine a count of the differentially coded POIs (204, 206, 208, 210) therein for each unit area, and graphically display the count (306) in the unit area.

[0053] Example 4 The system of any of Examples 1 to 3, wherein for a given unit area, the processor is configured to graphically indicate (204, 206, 208, 210) the count (306) by generating a new graphical display that reflects the count of differently graphically encoded POIs therein.

[0054] Example 5 The system of any of Examples 1 to 3, wherein for a given unit area, the processor is configured to reflect the count (306) by combining the differently graphically encoded POIs (204, 206, 208, 210) into a single POI (212) that is graphically encoded to represent each of the differently graphically encoded POIs therein.

[0055] Example 6 The method includes receiving (202, 302) a cardiac anatomical surface. A plurality of electrophysiological (EP) data points are received, each including (i) a respective location on the cardiac anatomical surface and (ii) a respective value of an EP parameter indicative of arrhythmia at that location. Respective criteria are applied to the value of the EP data point. For each EP data point whose value meets the respective criteria, the EP data point is graphically encoded to generate a point of interest (POI) (204, 206, 208, 210, 212). POIs for at least two types of EP parameters indicative of arrhythmia are overlaid on the anatomical surface to generate a POI map reflecting surface locations that are likely to be arrhythmogenic. The POI map is visualized to a user.

[0056] It will be understood that the above-described embodiments are given by way of example, and that the present disclosure is not limited to what is particularly shown and described hereinabove. Rather, the scope of the present disclosure includes both combinations and subcombinations of the various features described above, as well as variations and modifications thereof that would occur to one skilled in the art upon reading the foregoing description and that are not disclosed in the prior art. Documents incorporated by reference into this patent application are to be considered an integral part of this application, provided that, to the extent that any term in these incorporated documents is defined in a manner that contradicts a definition expressly or implicitly made herein, only the definition herein shall be considered.

[0057] [Embodiment] (1) a display; 1. A processor, comprising: Receive the cardiac anatomical surface, receiving a plurality of electrophysiological (EP) data points, the EP data points including (i) respective locations on the cardiac anatomical surface and (ii) respective values ​​of EP parameters indicative of arrhythmia at the locations; applying each criterion to the values ​​of the EP data points; For each EP data point whose value meets a respective criterion, graphically encoding said EP data point to generate a point of interest (POI); overlaying POIs of at least two types of EP parameters indicative of arrhythmia onto the anatomical surface to generate a POI map reflecting surface locations that are likely to be arrhythmogenic; a processor configured to visualize the POI map to a user on the display. (2) The system described in embodiment 1, wherein the EP parameter indicating the arrhythmia is of a type selected from a list including at least two of cycle length, local ripple percentage, local activation time (LAT), bipolar potential, excitation wave velocity, spatiotemporal dispersion gradient, and complex fractionated atrial potential (CFAE). (3) The system of embodiment 1, wherein the processor is configured to visualize the POI map by dividing the cardiac anatomical surface into unit areas of a predetermined size and shape, determine a count of differentially coded POIs therein for each unit area, and graphically display the count in the unit area. (4) The system of embodiment 3, wherein for a given unit area, the processor is configured to graphically show the count by generating a new graphical display that reflects the count of the differently graphically encoded POIs therein. (5) The system of embodiment 3, wherein for a given unit area, the processor is configured to reflect the count by combining the differently graphically encoded POIs into a single POI that is graphically encoded to represent each of the differently graphically encoded POIs therein.

[0058] (6) receiving a cardiac anatomical surface; and receiving a plurality of electrophysiological (EP) data points including (i) respective locations on the cardiac anatomical surface and (ii) respective values ​​of EP parameters indicative of arrhythmia at the locations; applying respective criteria to the values ​​of the EP data points; For each EP data point whose value meets a respective criterion, graphically encoding said EP data point to generate a point of interest (POI); overlaying POIs of at least two types of EP parameters indicative of arrhythmia onto the anatomical surface to generate a POI map reflecting surface locations that are likely to be arrhythmogenic; and visualizing the POI map to a user. (7) The method described in embodiment 6, wherein the EP parameter indicative of the arrhythmia is of a type selected from a list including at least two of cycle length, local ripple percentage, local activation time (LAT), bipolar potential, excitation wave velocity, and complex fission atrial potential (CFAE). (8) The method of embodiment 6, wherein visualizing the POI map includes dividing the cardiac anatomical surface into unit areas of a predetermined size and shape, determining for each unit area a count of differentially coded POIs therein, and graphically displaying the count in the unit area. (9) The method of embodiment 8, wherein for a given unit area, graphically indicating the count includes generating a new graphical display reflecting the count of the differently graphically encoded POIs therein. (10) The method of embodiment 8, wherein for a given unit area, reflecting the count includes combining the differently graphically encoded POIs into a single POI that is graphically encoded to represent each of the differently graphically encoded POIs therein.

Claims

1. The display and 1. A processor, comprising: Receive the cardiac anatomical surface, receiving a plurality of electrophysiological (EP) data points including (i) respective locations on the cardiac anatomical surface and (ii) respective values ​​of EP parameters indicative of arrhythmia at the locations; applying respective criteria to the values ​​of the EP data points; For each EP data point whose value meets a respective criterion, graphically encoding said EP data point to generate a point of interest (POI); overlaying POIs of at least two types of EP parameters indicative of arrhythmia onto the anatomical surface to generate a POI map reflecting surface locations that are likely to be arrhythmogenic; a processor configured to visualize the POI map to a user on the display.

2. 2. The system of claim 1, wherein the EP parameter indicative of the arrhythmia is of a type selected from a list including at least two of cycle length, local ripple percentage, local activation time (LAT), bipolar potential, excitation wave velocity, spatiotemporal dispersion gradient, and complex fragmented atrial potential (CFAE).

3. 2. The system of claim 1, wherein the processor is configured to visualize the POI map by dividing the cardiac anatomical surface into unit areas of a predetermined size and shape, determine for each unit area a count of differentially coded POIs therein, and graphically display the count in the unit area.

4. 4. The system of claim 3, wherein for a given unit area, the processor is configured to graphically indicate the count by generating a new graphical display that reflects the count of the differently graphically encoded POIs therein.

5. 4. The system of claim 3, wherein for a given unit area, the processor is configured to reflect the count by combining the differently graphically encoded POIs into a single POI that is graphically encoded to show each of the differently graphically encoded POIs therein.

6. Receiving a cardiac anatomical surface; receiving a plurality of electrophysiological (EP) data points including (i) respective locations on the cardiac anatomical surface and (ii) respective values ​​of EP parameters indicative of arrhythmia at the locations; applying respective criteria to the values ​​of the EP data points; For each EP data point whose value meets a respective criterion, graphically encoding said EP data point to generate a point of interest (POI); overlaying POIs of at least two types of EP parameters indicative of arrhythmia onto the anatomical surface to generate a POI map reflecting surface locations that are likely to be arrhythmogenic; and visualizing the POI map to a user.

7. 7. The method of claim 6, wherein the EP parameter indicative of the arrhythmia is of a type selected from a list including at least two of cycle length, local ripple percentage, local activation time (LAT), bipolar potential, excitation wave velocity, and complex fragmented atrial potential (CFAE).

8. 7. The method of claim 6, wherein visualizing the POI map comprises dividing the cardiac anatomical surface into unit areas of a predetermined size and shape, determining for each unit area a count of differentially coded POIs therein, and graphically showing the count in the unit area.

9. 9. The method of claim 8, wherein for a given unit area, graphically indicating the count comprises generating a new graphical display reflecting the count of the differently graphically encoded POIs therein.

10. 9. The method of claim 8, wherein, for a given unit area, reflecting the count includes combining the differently graphically encoded POIs into a single POI that is graphically encoded to show each of the differently graphically encoded POIs therein.

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