composite ablation instructions over an anatomical map

Abstract

A method includes receiving an anatomical mapping of the wall tissue of at least a portion of a heart chamber. During ablation, the positions of electrodes from a catheter within the heart chamber are received. At least some of the electrode positions are projected onto a surface of the mapping. The shortest path between pairs of projected positions of adjacent electrodes is found. When a path has a path length below a given threshold path length, some paths in the path are indicated using a first indication representing continuous ablation. Other paths in the path are indicated using a second indication representing an ablation gap based on catheter geometry. A grid ablation label is generated based on the first and second indications and an ablation model. The grid ablation label is overlaid on the anatomical mapping to generate an ablation mapping and is graphically encoded according to the first and second indications. The graphically encoded ablation mapping is presented to a user.

Description

Technical Field

[0001] This disclosure relates in general to cardiac ablation, and more specifically to systems and methods for real-time planning and monitoring of cardiac ablation using anatomical mapping. Background Technology

[0002] Previous patent documents have proposed providing indications of ablation points on anatomical mappings of the inner walls of the heart chambers. For example, U.S. Patent 10,588,692 describes how to find gaps between multiple ablation sites in the heart by projecting the positions of the sites in a three-dimensional coordinate system onto a simulated plane, identifying a set of the shortest three-dimensional paths connecting the pairs of projected positions of the sites, and reporting the gap as the longest path in that set.

[0003] This disclosure will be more fully understood in conjunction with the accompanying drawings and through the following detailed description of embodiments thereof, wherein: Attached Figure Description

[0004] Figure 1 This is a schematic diagram of a catheter-based electroanatomical (EA) mapping and ablation system according to an example of this disclosure; Figure 2 This is a schematic diagram of ablation indication on a mapping surface of a cardiac chamber after a chamber has been ablated by a loop catheter, according to an example of this disclosure; Figure 3 The ablation mapping of the cardiac chambers is derived using the disclosed composite ablation indication algorithm according to the examples of this disclosure; and Figure 4 This is a flowchart illustrating, schematically, an example of a method for generating ablation maps of cardiac chambers according to the present disclosure. Detailed Implementation

[0005] SUMMARY In cardiac ablation procedures, such as pulmonary vein isolation (PVI) for the treatment of atrial fibrillation, the physician ablates tissue in a specific anatomical region (e.g., the entire circumference of the pore of the PV). Ablation (such as ablation using pulsed field ablation (PFA) techniques) may require several iterations to completely cover the entire circumference of the pore. Each iteration requires moving the multi-electrode ablation catheter to an area that the physician deems insufficiently ablated or not ablated at all.

[0006] Ablation mapping, which includes anatomical 3D mapping, can assist physicians by displaying graphic-coded ablation tags to indicate the locations where ablation has been performed. The ablation tags are positioned on the surface of the anatomical 3D mapping and include ablation tags initially positioned close enough to the surface of the anatomical 3D mapping and projected onto the surface.

[0007] However, for various reasons, the projection of ablation data onto the anatomical mapping surface can lead to inaccurate representation of the position and continuity of ablation indicators on the anatomical structure surface: 1. Due to various factors (e.g., catheter movement due to respiration, limited number of anatomical data points collected during mapping, mapping errors, etc.), the surface of an anatomical mapping map may not always represent the actual anatomical structure. 2. Ablation catheters can be moved (e.g., pushed) from their normal position by applying force to the tissue before or during ablation. 3. Complex multi-electrode catheters (e.g., loop or multi-ridged, such as flower-shaped or basket-shaped catheters), especially those performing bipolar ablation, can produce ablation labels that are not correctly projected by the nearest neighbor projection, primarily due to the following reasons: 3.1. Bipolar ablation generates the flow of current (or electromagnetic field in PFA) between ablation electrodes, which is the opposite of unipolar focal zone ablation, for example, generating the flow of current (or electromagnetic field in PFA) between the ablation electrode and the nearest tissue, and is therefore more suitable for nearest neighbor projection. 3.2. Incorrect representation of projection indicators (e.g., graphically coded grid labels) on mapping of ablation gaps between certain electrodes (such as the proximal and distal electrodes of a loop catheter) that are not part of a bipolar ablation sequence. 3.3. Lack of continuity between projected ablation indicators (e.g., grid labels) of a pair of electrodes as part of a bipolar ablation sequence. Such a lack of continuity can give the physician the impression that the ablation gap is located in the region, primarily due to anatomical surface mapping artifacts as mentioned in paragraphs 3.1 and 3.2 above.

[0008] Another problem leading to inaccurate representation of location and ablation continuity on mapping (such as incorrectly representing ablation gaps) is the limited number of ablation data points. This is due to the clinical motivation to achieve continuous blockage of arrhythmias while minimizing damage to cardiac tissue. Therefore, each erroneous ablation location on the mapping can be significant.

[0009] The aforementioned and other issues can cause ablation indicators (e.g., graphic coded labels) to fail to indicate an existing ablation gap or to incorrectly indicate an ablation gap when it does not exist. Such errors make it difficult for physicians to determine where to indicate further ablation or whether ablation is unnecessary.

[0010] The examples described herein provide ablation mapping techniques that consistently show ablation gaps and largely eliminate inaccuracies caused by the problems listed above.

[0011] In one example, the processor runs the publicly disclosed algorithm steps: 1. Only when the distance to the mapping surface is less than the threshold projection distance (e.g., less than 7 mm) should any suitable projection method be used to project the electrode positions of the multi-electrode catheter onto the anatomical mapping surface. 2. Use the shortest path algorithm (such as Dijkstra's geodesy) to connect the locations of projected electrodes on the anatomical mapping surface. 3. Visual indications of the connection paths between paired projected electrode locations are created by limiting the geodesic paths between the projected electrode locations to clinically acceptable limits (e.g., within a predefined threshold path length). This step provides greater certainty for the nearest electrode that has produced sequential ablation than would otherwise be indicated by the mapping location. 4. If the connection between the projected electrode positions cannot achieve effective ablation due to catheter geometry (for electrodes that are not part of a bipolar ablation sequence and cannot achieve effective ablation between them), a visual indication of the potential gap is created along the path. When this step is applied to a loop ablation catheter, the processor indicates the path between the projected proximal-distal electrode positions as the ablation gap for the proximal-distal electrodes as part of the ablation sequence. For example, a physician may open only 2 to 8 electrodes instead of 1 to 10, so the gap will be between electrodes 2 and 8. 5. For each ablation case, repeat steps 1-4 to indicate the connection path and overwrite previous indications of potential gaps along the same path. As more ablation cases are analyzed, this step removes possible false positive indications of ablation gaps from the mapping.

[0012] Although the disclosed technology is presented for annular catheters, it can be adapted to other catheter geometries, such as various strips, flowers, grids, or baskets, with necessary modifications.

[0013] The disclosed techniques can also be modified as necessary to improve diagnostic mapping accuracy or reduce diagnostic mapping time, because mapping procedures typically collect far more data points and use more flexible catheters, resulting in mapping label position errors still existing in these diagnostic mapping maps.

[0014] System Description Figure 1 This is a schematic diagram of a catheter-based electroanatomical (EA) mapping and ablation system 10 according to an example of this disclosure.

[0015] System 10 includes a loop ablation catheter 14, which is percutaneously inserted by physician 24 through the patient's vascular system into a chamber or vascular structure of the heart 12 (shown in illustration 45). Typically, a delivery sheath catheter is inserted into a heart chamber (such as the left or right atrium) near the desired location in the heart 12. Catheter 14 can then be inserted into the delivery sheath catheter to reach the desired location. These catheters may include catheters dedicated to pacing, catheters for sensing intracardiac electrogram signals, catheters dedicated to ablation, and / or catheters dedicated to both EA mapping and ablation. The loop catheter 14 shown herein is configured for sensing bipolar electrograms and applying PFA. Physician 24 may contact the distal end assembly 28 of catheter 14 with the heart wall to ablate the target site in the heart 12.

[0016] As shown in Illustration 65, the distal end assembly 28 includes a plurality of electrodes 26 distributed on a curved spline 22. The conduit 14 may include a position sensor 29 embedded in or near the distal end assembly 28 on the shaft 46 of the conduit 14 to track the position and orientation of its distal end assembly 28. Optionally and preferably, the position sensor 29 is a magnetically based position sensor having three magnetic coils for sensing three-dimensional (3D) position and orientation.

[0017] The magnetic-based position sensor 29 operates in conjunction with a position pad 25, which includes a plurality of magnetic coils 32 configured to generate a magnetic field in a predefined workspace. Real-time positioning of the distal end assembly 28 of the conduit 14 can be tracked based on the magnetic field generated by the position pad 25 and sensed by the magnetic-based position sensor 29. Details of the magnetic-based position sensing technology are described in U.S. Patents 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.

[0018] System 10 includes one or more electrode patches 38 positioned to contact the skin of patient 23 to establish a position reference for impedance-based tracking of positioning pad 25 and electrodes 26. For impedance-based tracking, current is directed toward electrodes 26 and sensed at the electrode skin patch 38, allowing triangulation of the position of each electrode via the electrode patch 38. Details of the impedance-based position tracking technique are described in U.S. Patents 7,536,218, 7,756,576, 7,848,787, 7,869,865, and 8,456,182.

[0019] Recorder 11 displays cardiac signals 21 acquired using surface ECG electrodes 18 (e.g., electrograms acquired at separately tracked cardiac tissue locations) and intracardiac electrograms acquired using electrodes 26 of catheter 14. Recorder 11 may include pacing capabilities for pacing rhythms and / or may be electrically connected to a separate pacemaker.

[0020] System 10 includes an ablation energy generator 50 adapted to conduct ablation energy to one or more electrodes 26 configured for ablation. The energy generated by the ablation energy generator 50 may include, but is not limited to, radio frequency (RF) energy or pulsed field (PF) energy, which includes unipolar or bipolar high-voltage DC pulses (i.e., PFA).

[0021] The patient interface unit (PIU) 30 is configured to establish electrical communication between the catheter, electrophysiology equipment, power supply, and workstation 55 to control the operation of system 10 and receive EA signals from the catheter. The electrophysiology equipment of system 10 may include, for example, multiple catheters, positioning pads 25, surface ECG electrodes 18, electrode patches 38, ablation energy generator 50, and recorder 11. Optionally and preferably, the PIU 30 also has processing capabilities for real-time calculation of catheter position and for performing ECG calculations.

[0022] Workstation 55 includes memory 57, a processor 56 unit with a memory or storage device in which appropriate operating software is loaded, and user interaction capabilities. Workstation 55 may provide multiple functions, optionally including: (i) three-dimensional (3D) modeling of endocardial anatomy and rendering the model or anatomical mapping 20 for display on display device 27; (ii) displaying, on display device 27, activation sequences (or other data) compiled from recorded cardiac signals 21, on representative visual markers or images superimposed on the rendered anatomical mapping 20; (iii) displaying the real-time position and orientation of multiple catheters within the cardiac chambers; and (iv) displaying, on display device 27, sites of interest (such as where ablation energy has been applied). A commercial product embodying the elements of system 10 could be CARTO. ™ The 3 System was purchased from Biosense Webster, Inc., 31A Technology Drive, Irvine, CA 92618.

[0023] In the disclosed example, processor 56 runs an algorithm to generate an ablation map that shows the ablation gap with increased confidence, such as... Figure 2 and Figure 3 As shown.

[0024] In some examples, processor 56 typically includes a general-purpose computer programmed in software to perform the functions described herein. This software may be downloaded to the computer electronically, for example, via a network, or alternatively or additionally disposed and / or stored on a non-transitory tangible medium, such as magnetic storage, optical storage, or electronic storage.

[0025] This configuration of system 10 is illustrated by way of example to illustrate certain problems solved by the examples of this disclosure and to demonstrate the application of these examples in enhancing the performance of such systems. However, the examples of this disclosure are by no means limited to this particular example system, and the principles described herein can be similarly applied to other medical systems. For example, other types of multipolar catheters, such as basket catheters, can be used.

[0026] Composite ablation indication As described above, the disclosed technique provides an algorithm for generating ablation maps that show the ablation gap at an increased confidence level, as determined by retrospective studies. Figure 2 Some algorithmic steps are described in the text. Figure 2 The following is an analysis of an ablation instance based on an example of this disclosure, showing a schematic diagram of ablation indications (250, 252, 254) on a mapping surface 202 of the cardiac chamber following chamber ablation performed by the loop catheter 28.

[0027] As shown in the figure, the position of ablation electrode 26 is projected (240) onto position 230 on the mapping surface 202. The projection 240 of electrode 1 is not considered because its calculated projection distance (241) is higher than the threshold projection distance 242 (e.g., greater than 7 mm).

[0028] The edge electrode (such as proximal electrode 1) may have two protrusions, one protrusion relative to the protrusion of electrode 2 and the other protrusion relative to the protrusion of electrode 10. Both projections are considered in this disclosure.

[0029] The disclosed algorithm divides the ablation indications on the mapping surface 202 into three groups: Group 1: Indication 250 between adjacent electrode projection positions (e.g., 230A and 230B) on the mapping surface 202, indicating a continuous ablation path 260.

[0030] Group 2: An indication 252 between adjacent electrode projection locations (e.g., 230C and 230D) on the mapping surface 202, which also indicates a sequential ablation path 260, albeit a longer path. For this purpose, a predefined path length threshold 255 is set sufficiently high. This crucial step provides greater certainty for the nearest electrodes (such as (6, 7)), resulting in sequential ablation that can be accounted for by the length between the projection locations (e.g., 230C and 230D).

[0031] Instructions 250 and 252 are collectively referred to as "Instructions 1".

[0032] Group 3: A second indicator 254 between the projected positions of adjacent electrodes (e.g., 230E and 230F) on the mapping surface 202, indicating the path of the ablation gap caused by ineffective PFA between certain adjacent electrodes. Figure 2 In the case of the annular catheter 28, the gap indicator 254 is located between the projected positions of the proximal electrode 1 and the distal electrode 10 of the catheter.

[0033] Ablation surgery includes Figure 2 Many examples of the types shown. Figure 3 Ablation mappings based on the above analysis applied to multiple ablation cases are depicted.

[0034] Ablation map based on composite ablation indication Figure 3 The ablation mapping 300 of the cardiac chamber is derived using the disclosed composite ablation indication algorithm according to the examples of this disclosure. Ablation mapping 300 is defined herein as an anatomical mapping 302 superimposed / overlapped with grid ablation labels 304.

[0035] In the context of this disclosure, ablation tags 304 are associated with ablation points in their displayed mesh, defined by a 3D mapping coordinate system. The ablation point mesh densely divides the 3D space (e.g., in sub-millimeter units). The density of the ablation tags is based on a dipole model of PFA energy deposition around each electrode.

[0036] Map 300 is also based on Figure 2 Indications 250, 252, and 254 are used to indicate the area of ​​ablation label 304, which is graphically encoded 306 to indicate continuous ablation and graphically encoded 308 to indicate ablation gaps.

[0037] Ablation mapping 300 shows ablation grid labels 308, which are graphically encoded to indicate possible ablation gaps. Figure 2 Instruction 254 is an example of the export of Graphics Encoding 308.

[0038] As mentioned above, the mapping map 300 is also based on Figure 2Instruction 252 is used to minimize erroneous gap identification. Mapping map 300 helps physicians complete PFA treatment and minimize additional ablation.

[0039] Map 300 can be generated offline using stored data, or generated during clinical ablation procedures and updated in real time as the ablation procedure progresses.

[0040] Method of indicating ablation on an anatomical map Figure 4 This is a flowchart illustrating, schematically, a method for generating an ablation mapping of a heart chamber according to an example of the present disclosure. According to the presented example, the algorithm execution process begins at mapping receiving step 402, where processor 56 receives an anatomical mapping 302 of the wall tissue of at least a portion of the heart chamber.

[0041] At step 404, the processor also receives the position of the intracardiac catheter electrode 26 during the ablation instance.

[0042] Next, in projection step 406, the processor projects the electrode positions onto surface 202 of the anatomical mapping map 302.

[0043] At inspection step 408, the processor checks the distance (241) of each projection (i.e., the distance between the electrode position and the projection position). If this distance exceeds a predefined distance threshold, the processor discards the projection from consideration at projection discard step 410. This step is intended to increase the confidence of the disclosed method, as accepting excessively long projections may cause the algorithm to overestimate ablation continuity, thereby ignoring ablation gaps.

[0044] For a valid projection, i.e., when the projection distance (241) is lower than the predefined threshold projection distance 242, the processor finds the shortest path between the projection positions of adjacent electrodes on the mapping map 302 in the pathfinding step 412, such as... Figure 2 As shown.

[0045] In step 414, the processor checks the catheter geometry for any projected paths that do not indicate effective ablation, as identified in step 412. For the example of the annular catheter 28, the path connecting the proximal (1) electrode position 230E and the distal (10) electrode position 230F of the projected path indicates (254) an ablation gap. The gap between the proximal and distal electrodes is inherent to many catheter types, and therefore, regardless of the protrusion characteristics, there is no ablation between these electrodes.

[0046] In instruction step 420, the processor indicates invalid paths (254) as possible ablation gaps.

[0047] After considering any invalid electrode pairs in step 414, the processor checks whether the shortest path between any other projected locations of adjacent electrodes exceeds a predefined threshold path length (255).

[0048] If the answer is "yes", then at step 418, the processor avoids indicating that path. This step is designed to increase the confidence of the disclosed model, as indicating an overly long path can cause the algorithm to miss ablation gaps.

[0049] If the answer to step 414 is "no", the processor indicates the examined path as a continuous ablation path at path indication step 422.

[0050] At ablation tag generation step 424, the processor generates mesh ablation tags 304 based on the instructions from steps 420 and 422. The tags are distributed according to a model (e.g., a dipole model) of the PFA energy density in the tissue.

[0051] At the overlay step 426, the processor overlays (i.e., superimposes) the mesh ablation tag 304 onto the anatomical mapping 302 to generate the ablation mapping 300.

[0052] At the graphic encoding step 428, the processor graphicly encodes the grid ablation tags 304 (306, 308) to indicate ablation gaps. Graphically encoding the tag ablation map may include coloring the ablation tags on continuous areas with one color and coloring the ablation tags on ablation gaps with another color.

[0053] Finally, at the ablation mapping presentation step 430, the processor can present the graphically encoded ablation mapping 300 to the user on the display device 27.

[0054] Figure 4 The flowchart is simplified to describe a single instance of ablation; however, in actual procedures, many ablation instances may occur, causing the processor to update the ablation mapping 300 multiple times during the procedure. As more ablation instances are considered, the region encoded (308) as having gaps can become encoded (306) as a continuous region. If the ablation procedure is performed completely, the final ablation mapping 300 will not show gaps.

[0055] Map 300 can be generated using offline data, or generated during clinical ablation procedures and updated in real time as the ablation procedure progresses. Example

[0056] Example 1 A method includes: receiving an anatomical mapping (302) of the wall tissue of at least a portion of a cardiac chamber; receiving the positions of electrodes (26) of a catheter (14) within the cardiac chamber during ablation application; projecting (240) at least some of the positions of the electrodes (26) onto a surface (202) of the mapping; identifying the shortest path (260) between paired projection positions (230) of adjacent electrodes (26); indicating some paths in the path using a first indication (250, 252) of sequential ablation when the path (260) has a path length below a given threshold path length (255); indicating other paths in the path using a second indication (254) of the ablation gap based on the catheter geometry; and generating a grid ablation label (304) based on the first indication (250, 252) and the second indication (254) and the ablation model. A grid ablation label is overlaid on the anatomical mapping (302) to generate an ablation mapping (300), and the label (304) is graphically encoded (306, 308) according to a first instruction (250, 252) and a second instruction (254), respectively. The graphically encoded ablation mapping (300) is then presented to the user.

[0057] Example 2 According to the method described in Embodiment 1, the projection (240) of the location includes: checking the distance (241) between the location and the corresponding projection location (230), and discarding one or more projection locations (240) whose distance (241) exceeds a threshold projection distance (242).

[0058] Example 3 According to the method of any one of Embodiments 1 and 2, finding the shortest path (260) includes finding a geodesic on the surface (202) of the anatomical mapping.

[0059] Example 4 According to any one of Embodiments 1 to 3, wherein indicating (254) the path using the second indication of the ablation gap based on the geometry of the catheter (14) includes: for annular (28) catheters, indicating the path generated by the projection of the nearest side electrode (26) and the farthest side electrode (26) of the catheter as the ablation gap.

[0060] Example 5 According to any one of Examples 1 to 4, generating the mesh ablation label (304) includes using a dipole model.

[0061] Example 6 According to any one of Examples 1 to 5, the graphic encoding (306, 308) of the label (304) of the ablation mapping (300) includes: coloring the ablation label (304) on a continuous area with one color, and coloring the ablation label on the ablation gap with another color.

[0062] Example 7 According to any one of Examples 1 to 6, the anatomical mapping (302) is an electroanatomical (EA) mapping.

[0063] Example 8 A system (10) includes a display device (27) and a processor (56). The processor is configured to: (i) receive an anatomical mapping (302) of the wall tissue of at least a portion of a cardiac chamber; (ii) receive the positions of electrodes (26) of a catheter (14) within the cardiac chamber during the application of ablation; (iii) project (240) at least some of the positions of the electrodes onto a surface (202) of the mapping; (iv) find the shortest path (260) between paired projection positions (230) of adjacent electrodes (26); and (v) when the path has a path (260) length below a given threshold path length (255), utilize a first indication (250, ) of sequential ablation. (vi) Indicate some paths in the path; (vii) Indicate other paths in the path using a second indication (254) of the ablation gap based on the catheter geometry; (vii) Generate a grid ablation label (304) according to the first indication and the second indication and the ablation model; (viii) Overlay the grid ablation label (304) onto the anatomical mapping (302) to generate an ablation mapping (300); (ix) Graphically encode the ablation mapping (306, 308) according to the first indication and the second indication of the path; and (x) Present the graphically encoded (306, 308) ablation mapping (300) to the user on the display device (27).

[0064] It should be understood that the above embodiments are cited by way of example, and this disclosure is not limited to what has been shown and described above. Rather, the scope of this disclosure includes combinations and sub-combinations of the various features described above, as well as variations and modifications thereof, which will occur to those skilled in the art upon reading the above description and which are not disclosed in the prior art.

Claims

1. A method comprising: Anatomical mapping of at least a portion of the wall tissue of the heart chamber; The position of the electrodes of the catheter received within the cardiac chamber during the application of ablation; At least some of the locations of the electrodes are projected onto the surface of the mapping map; Find the shortest path between the paired projection positions of adjacent electrodes; When the path has a path length below a given threshold path length, a first indication of continuous ablation is used to indicate some of the paths in the path; Based on the catheter geometry, a second indicator of the ablation gap is used to indicate other paths within the pathway; Generate grid ablation labels based on the first and second instructions and the ablation model; The ablation tags are superimposed on the anatomical mapping to generate an ablation mapping; The ablation mapping is graphically encoded according to the first and second indications of the path; as well as Present users with graphically encoded ablation maps.

2. The method according to claim 1, wherein, Projecting the location includes: checking the distance between the location and the corresponding projection location, and discarding one or more projection locations whose distance exceeds a threshold projection distance.

3. The method according to any one of claims 1 to 2, wherein, Finding the shortest path includes locating geodesics on the surface of the anatomical mapping.

4. The method according to any one of claims 1 to 2, wherein, Indicating the path based on the catheter geometry using the second indication of the ablation gap includes, for annular catheters, indicating the path generated by the projections of the nearest side electrode and the farthest side electrode of the catheter as the ablation gap.

5. The method according to any one of claims 1 to 2, wherein, Generating the mesh ablation labels includes using a dipole model.

6. The method according to any one of claims 1 to 2, wherein, Graphical encoding of the ablation map includes: coloring the ablation tag above a continuous region with one color, and coloring the ablation tag above the ablation gap with another color.

7. The method according to any one of claims 1 to 2, wherein, The anatomical mapping is an electroanatomical (EA) mapping.

8. A system comprising: Display device; and Processor, the processor being configured to: Anatomical mapping of at least a portion of the wall tissue of the heart chamber; The position of the electrodes of the catheter received within the cardiac chamber during the application of ablation; At least some of the locations of the electrodes are projected onto the surface of the mapping map; Find the shortest path between the paired projection positions of adjacent electrodes; When the path has a path length below a given threshold path length, a first indication of continuous ablation is used to indicate some of the paths in the path; Based on the catheter geometry, a second indicator of the ablation gap is used to indicate other paths within the pathway; Generate grid ablation labels based on the first and second instructions and the ablation model; The ablation tags are superimposed on the anatomical mapping to generate an ablation mapping; The ablation mapping is graphically encoded according to the first and second indications of the path; as well as The display device presents the user with a graphically encoded ablation map.

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