Impedance-based tracking of position of catheter relative to lumen wall

Abstract

A method of indicating movement of a receiving electrode of a distal end assembly relative to a tissue lumen wall, the method comprising: using a distal end assembly comprising a plurality of electrodes arranged in a configuration of the distal end assembly; transmitting AC signals between the one or more reference electrodes and a plurality of receiving electrodes attached to the plurality of 5 strips; calculating a plurality of impedance values over time based on a received signal at each of the receiving electrodes; calculating a gradient of the impedance value over time at the receiving electrode; dynamically presenting a virtual representation of the distal end assembly on a display, including a virtual representation of the plurality of receiving electrodes; and dynamically adjusting the displayed Figure 10-shaped feature of at least one of the receiving electrodes based on the calculated gradient of the impedance over time. Related apparatus and methods are also described.

Description

Technical Field

[0001] In some examples, the present disclosure relates to electroanatomical mapping using an intracardiac catheter and, more particularly, to displaying and / or providing guidance to a physician during mapping. Background Art

[0002] Internal organs include tissues and / or body fluids that can vary within different parts of an internal organ and can also vary within different regions of the chambers of an internal organ, such as the different chambers of the heart. Thus, tissue proximity as determined based on an electrical signal provided by one or more electrodes can be based on specific tissue characteristics at a given location within the internal organ, such as at different regions of the heart.

[0003] U.S. Patent No. 10,952,637 describes a method that includes receiving, from a probe that includes electrodes and is positioned inside a cavity of a patient's organ: (i) a proximity signal indicating the proximity of the electrodes to the wall of the cavity, and (ii) a position signal indicating the position of the electrodes within the cavity.

[0004] U.S. Patent Application Publication No. 2023 / 0112251 describes a system that includes a catheter and a processor. The catheter includes a distal end assembly coupled to a distal end of a shaft for insertion into a cavity of a patient's organ, the distal end assembly including (i) one or more functional electrodes configured to be placed in contact with the wall tissue of the cavity, and (ii) a reference electrode configured to be placed in the cavity but not in contact with the wall tissue. The processor is configured to (i) estimate one or more impedances between one or more of the functional electrodes and the reference electrode, and (ii) for at least one of the one or more functional electrodes, determine whether the functional electrode is in physical contact with the wall tissue based on the impedance.

[0005] Overview

[0006] Determining and / or indicating a direction towards or away from a tissue wall can assist a physician in guiding a medical device towards, away from, or substantially along the tissue wall that defines the perimeter of a cavity.

[0007] One of the intents of aspects of the present disclosure is to assist a physician in guiding a catheter and / or a catheter distal end assembly within a cardiac chamber without the use of X-ray fluoroscopy.

[0008] Potential beneficial effects can assist a physician in guiding a catheter and / or the distal end assembly of the catheter to a region of interest, such as a pulmonary vein.

[0009] Tissue impedance is generally greater than the impedance of blood, and it is expected that the impedance value measured at an electrode closer to the tissue will be greater than that measured at an electrode farther from the tissue.

[0010] Example solutions include measuring impedance at one or more electrodes in a body cavity and identifying a gradient of change in impedance over time for each of the one or more electrodes.

[0011] An increase in impedance measured at an electrode (e.g., a positive gradient) indicates that the electrode is moving towards the tissue wall. A decrease in impedance (e.g., a negative gradient measured at the electrode) indicates that the electrode is moving away from the tissue wall. For a basket or balloon catheter, when a physician manipulates the distal end assembly, some electrodes may advance towards the tissue wall while other electrodes opposite the direction of movement will move away from the tissue wall. It may be useful for the physician to receive an indication of which electrodes are approaching the tissue wall. Additionally, it may be useful for the physician to receive an indication of which electrodes are moving in the direction away from the tissue. Providing this information in real time can assist the physician in manipulating and orienting the distal end assembly in the desired orientation within the chamber, such as to reach the area of interest.

[0012] In some cases, for example, when circumferentially positioned electrodes indicate a sharp increase in impedance while electrodes at the distal end of the distal end assembly indicate a relatively low or no increase in impedance, an entryway can be identified.

[0013] In some examples, when electrodes are distributed in three dimensions (3D) within a body cavity, data collected from more than one electrode may be used to calculate a 3D gradient of increasing impedance over time corresponding to the direction towards the surface of the tissue in 3D.

[0014] In some examples, a medical device, such as Figure 2 the basket-shaped distal end assembly 28, is displayed to the physician. When the physician is manipulating the catheter within a heart chamber, the display shows a virtual representation of the distal end assembly in its current orientation and position. This virtual representation can be shown in conjunction with the mapping of the chamber that has been modeled. Figure 1 shown together.

[0015] In some examples, the display can optionally display the increasing impedance over time by coloring or otherwise marking (e.g., brightness) the display of the electrodes corresponding to their impedance gradients over time. The physician can see which electrodes are approaching the tissue wall based on the color / brightness / other marking of the electrodes and manipulate the distal end accordingly.

[0016] In such examples, the display can also optionally display the direction of the maximum gradient, e.g., the direction in which the distal end assembly is approaching the tissue wall at the fastest rate, e.g., as an arrow pointing towards the tissue surface.

[0017] In some examples, the direction or arrow can be displayed in the direction away from the tissue surface, or perpendicular to the tissue surface, or approximately parallel to the tissue surface.

[0018] It should also be noted that impedance gradients can also be calculated and / or displayed by considering measurements of the position in space of receiving electrodes attached to a medical device (such as Figure 2 the distal end assembly 28) using one or more position sensors.

[0019] It should also be noted that one or more position sensors (such as magnetically based single axis sensors (SAS)) can be used to calculate and / or display impedance gradients while measuring the position of a medical device (such as Figure 2 the basket electrode assembly 28). BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Some examples of the present disclosure will now be described in conjunction with the accompanying drawings by way of example only. Referring now to the details of the drawings, it should be emphasized that the details shown are by way of example and for purposes of illustrative discussion of examples of the present disclosure. In this regard, the description in conjunction with the drawings enables those skilled in the art to understand how to practice examples of the present disclosure.

[0021] In the drawings:

[0022] Figure 1 is a simplified illustration of a catheter-based electrophysiological mapping and ablation system for an example in accordance with the presently disclosed subject matter;

[0023] Figure 2 is Figure 1 a more detailed isometric view of the expandable end assembly on the distal tip of the catheter of

[0024] Figure 3 is a simplified qualitative illustration showing impedance as a function of distance from the cavity wall tissue measured by electrodes in a body cavity in accordance with one aspect of the present disclosure;

[0025] Figure 4 is a simplified flowchart illustration of a method for indicating movement of receiving electrodes of a distal end assembly relative to a tissue cavity wall in accordance with one aspect of the present disclosure; and

[0026] Figure 5A and Figure 5B is a view of the end assembly of the catheter as displayed on a display and showing direction based on a spatial gradient superimposed on the display of the expandable catheter in accordance with one aspect of the present disclosure. Figure 2 DETAILED DESCRIPTION

[0027] Some examples of the present disclosure relate to intracardiac catheter-based electroanatomical mapping and, more particularly, to displaying and / or providing guidance to a physician during mapping.

[0028] To better understand some examples of the present disclosure, as in the accompanying drawings of Figure 3 、​Figure 4 and Figures 5A to 5B As shown in Figures 5A to 5B , the construction and operation of a catheter-based position tracking system including an expandable end assembly will first be referenced.

[0029] Referring to Figure 1 , which is a simplified illustration of an exemplary catheter-based electrophysiological mapping and ablation system in accordance with an example of the presently disclosed subject matter, showing an exemplary catheter-based electrophysiological mapping and ablation system 10. System 10 includes a plurality of catheters that are inserted by a physician 24 through the patient's vascular system via the skin into a chamber or vascular structure of the heart 12. Generally, a delivery sheath catheter is inserted into the left atrium or right atrium near a desired location in the heart 12. Then, one or more catheters can be inserted into the delivery sheath catheter 5 to reach a desired location in the heart 12. The plurality of catheters can include a catheter dedicated to sensing intracardiac electrogram (IEGM) signals, a catheter dedicated to ablation, and / or a catheter dedicated to both sensing and ablation. An example catheter 14 configured for sensing IEGM is illustrated herein. The physician 24 can place the distal tip 28 of the catheter 14 in contact with the heart wall for sensing a target site in the heart 12. For ablation, the physician 24 can similarly place the distal end of the ablation catheter in contact with the target site 10 for ablating tissue.

[0030] Catheter 14 is an exemplary catheter that includes one (preferably a plurality) of electrodes 66 that are optionally distributed above a plurality of strips 62 at the distal tip 28 and are configured to sense IEGM signals. Catheter 14 can additionally include a position sensor (not shown) embedded in or near the distal tip 28 for tracking the position and orientation of the distal tip 28. Optionally and preferably, the position sensor is a magnetic-based position sensor that includes three magnetic coils for sensing three-dimensional (3D) position and orientation.

[0031] The magnetic-based position sensor can operate in conjunction with a positioning pad 25 that includes a plurality of magnetic coils 32 configured to generate a magnetic field in a predefined workspace. The real-time position of the distal tip 28 of the catheter 14 can be tracked based on the magnetic field generated by the positioning pad 25 and sensed by the magnetic-based position sensor. Details of magnetic-based position sensing techniques are described in U.S. Patents Nos. 5,539,199; 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.

[0032] System 10 may include 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 66. For impedance-based tracking, current is directed toward electrodes 66 and sensed at the electrode skin patches 38 such that the position of each electrode can be triangulated via the electrode patches 38. Details of impedance-based positioning 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.

[0033] Recorder 11 may record and display electrocardiogram 21 captured using body surface ECG electrodes 18 and intracardiac electrogram (IEGM) captured using electrodes 66 of catheter 14. Recorder 11 may include pacing capabilities for pacing the heart rhythm and / or may be electrically connected to an independent pacemaker.

[0034] System 10 may include an ablation energy generator 50 adapted to conduct ablation energy to one or more electrodes at the distal tip of a catheter configured for ablation. The energy generated by 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 that can be used to effect irreversible electroporation (IRE)), or combinations thereof.

[0035] Patient interface unit (PIU) 30 is an interface configured to establish electrical communication between a catheter, other electrophysiological equipment, a power source, and a workstation 55 for controlling the operation of system 10. The electrophysiological equipment of system 10 may include, for example, multiple catheters, positioning pad 25, body surface ECG electrodes 18, electrode patches 38, ablation energy generator 50, and recorder 11. Optionally and preferably, PIU 30 further includes processing capabilities for performing real-time calculations of the position of the catheter and for performing ECG calculations.

[0036] Workstation 55 includes a memory, a processor unit having a memory or storage device with appropriate operating software stored therein, and user interface capabilities. Workstation 55 may provide a variety of functions, optionally including:

[0037] (1) Model the endocardial anatomy in three dimensions (3D) and present a 3D graphical representation of the model or anatomical map 20 for display on display device 27;

[0038] (2) Display on display device 27 an activation sequence (or other data) compiled from the recorded electrocardiogram 21 as representative visual markers or images superimposed on the presented anatomical map 20;

[0039] (3)Model the catheter inserted into the body in three dimensions (3D) and present a 3D graphical representation of the model for display on the display device 27;

[0040] (4)Display the real-time positions and orientations of multiple catheters within the heart chambers; and

[0041] (5)Display on the display device 27 the sites of interest where, for example, ablation energy is applied.

[0042] A commercial product embodying the elements of the system 10 may be CARTO TM 3 system is purchased from Biosense Webster, Inc., 31A Technology Drive, Irvine, CA 92618.

[0043] Various methods for measuring impedance

[0044] It should be noted that the technique for tracking the position of a catheter relative to tissue based on impedance can be used in various methods for measuring the impedance between electrodes.

[0045] In some examples, the impedance measurement can be performed between one or more reference electrodes on the catheter and several electrodes also in the patient's body cavity.

[0046] In some examples, the reference electrodes are located in or on the end assembly in a manner that prevents the reference electrodes from contacting the tissue.

[0047] In some examples, the impedance measurement can be performed between one or more reference electrodes that transmit an AC signal and several receiving electrodes also in the patient's body cavity. The AC signal is, by way of non-limiting example, an AC signal at a frequency in the kilohertz range such as 6.4 kHz on the end assembly of the catheter within the patient's body cavity.

[0048] In some examples, the impedance measurement can be performed between one or more electrodes on a patch on the patient's body and several electrodes in the patient's body cavity.

[0049] In some examples, the impedance measurement can be performed between one or more electrodes and several receiving electrodes. The one or more electrodes transmit an AC electrical signal on the expandable end assembly of the catheter within the patient's body cavity, and the several receiving electrodes are located on the outer surface or strips of the expandable end assembly. In some examples, the transmitting electrodes are positioned on the catheter in a manner that avoids contact with the cavity wall.

[0050] In some examples, the impedance measurement can be performed between one or more adjacent electrodes on the distal end assembly.

[0051] Calculation of impedance variation over time

[0052] It should be noted that techniques for tracking the position of an impedance-based catheter relative to tissue can be performed on the heart while the heart is beating. When the electrodes measure impedance values to calculate the change in impedance over time, the heart wall is moving.

[0053] In some cases, impedance is measured at the same time point relative to the cardiac cycle so that the movement of the distal end assembly can be measured at the same location relative to the heart wall.

[0054] In some cases, impedance is measured at different time points relative to the cardiac cycle, and the change in impedance due to the movement of the catheter end assembly is calculated. For example, a change in the maximum value of impedance during the heartbeat cycle can indicate movement towards or away from the heart wall. Another example, a change in the minimum value of impedance during the heartbeat cycle can indicate movement towards or away from the heart wall. Another example, a change in the average value of impedance during the heartbeat cycle can indicate movement towards or away from the heart wall.

[0055] Calculation of the direction relative to the tissue

[0056] It should be noted that tissue impedance is generally greater than blood impedance, and it is desirable to measure a greater impedance value at electrodes closer to the tissue than at electrodes immersed in blood away from the tissue wall.

[0057] In some examples, the normalized tissue proximity indication is normalized based on the patient-specific minimum and maximum impedance values of the patient.

[0058] In some examples, a gradient is calculated based on a number of impedance values.

[0059] The direction of the increasing value determined by the gradient is considered to be the direction towards the tissue wall. The direction of the decreasing value determined by the gradient is considered to be the direction away from the tissue wall. The direction perpendicular to the gradient direction is considered to be substantially parallel to the tissue wall.

[0060] Display

[0061] In some examples, after calculating the direction relative to the tissue (i.e., towards the tissue, away from the tissue, parallel to the tissue wall), the direction is optionally displayed by a display.

[0062] In some examples, the direction can optionally be displayed together with a virtual representation of the distal end assembly, indicating its real-time position and orientation in the rendered display in the 3D workspace.

[0063] In some examples, the color of the distal device or the electrodes on the distal device can be used to indicate whether the movement is towards the tissue wall, away from the tissue wall, or there is no impedance change (possibly equivalent to movement parallel to the tissue wall). Optionally, the intensity, shade, or hue of the displayed color can be changed based on the magnitude and direction of the gradient.

[0064] In some examples, additional graphical features may also indicate the proximity of each electrode to the tissue. As a non-limiting example, the electrode closest to the tissue may be framed by one color, and the electrode farthest from the tissue may be framed by another color.

[0065] In some examples, the intensity of the coloring of the distal device or the intensity of the coloring of the electrodes on the distal device may be used to indicate relative proximity.

[0066] In some examples, arrows corresponding to the direction of the tissue wall are shown.

[0067] Now refer to Figure 2 , which is Figure 1 a more detailed isometric view of the expandable end assembly on the distal tip of the catheter of

[0068] The expandable end assembly 28 includes a coupler 26 that connects to the shaft of the distal end of the catheter 14 and a push rod 58 that includes a distal portion 60. The push rod 58 is configured to be advanced and retracted through the catheter 14, for example, using a manipulator or a handle (not shown). The expandable end assembly 28 may include a plurality of strips 64. Each strip 64 may include a plurality of electrodes 66 disposed thereon (only some are labeled for simplicity). Optionally, the expandable end assembly 28 may include a nose connector 70 that connects to the distal portion 60 of the push rod 58.

[0069] In some examples, a reference electrode 59 may be attached to the push rod 59, as Figure 2 shown, or adjacent to the coupler 26, or adjacent to the nose connector 70. In some examples, more than one reference electrode 59 may be used, for example, one reference electrode adjacent to the coupler 26 and one reference electrode adjacent to the nose connector 70. The reference electrode 59 is optionally used to provide an AC signal for measuring the impedance between the electrode 66 and the reference electrode 59.

[0070] Figure 2 It is intended to show the electrodes 66 on the strips 64 that are disposed in a three-dimensional (3D) dispersion in space.

[0071] In some examples, the electrodes 66 disposed along the strip 64 may be disposed in a two-dimensional (2D) dispersion in space (i.e., in a plane).

[0072] Figure 2 Some expandable end assemblies 28 in physical contact with the cavity wall tissue 80 are shown.

[0073] In some examples, the catheter and / or the expandable end assembly 28 may include one or more position sensors (not shown) embedded in one or more locations at the distal end of the shaft 26, e.g., a position sensor (e.g., a multi-axis sensor); a position sensor disposed in the distal receptacle of the nose connector 70; and / or a position sensor (e.g., a single-axis sensor) disposed on one or more struts 54.

[0074] Before detailing at least one example of the present disclosure, it should be understood that the present disclosure is not necessarily limited in its application to the details of the construction and arrangement of the components and / or methods set forth in the following description and / or illustrated in the drawings and / or examples. The present disclosure is capable of having other examples, or of being practiced or carried out in various ways.

[0075] Now refer to Figure 3 , which is a simplified qualitative illustration showing impedance measured by an electrode in a body cavity as a function of distance from the cavity wall tissue.

[0076] Figure 3 A graph is shown having an X-axis 302 of qualitative proximity values to the cavity wall tissue and a Y-axis 304 of qualitative impedance values. Figure 3 The graph of includes a line 306, which shows the qualitative value of the impedance value of the electrode in the body cavity as a function of proximity to the cavity wall, and also includes the continuation of line 306 in the region where the electrode contacts the cavity wall with various amounts of pressure.

[0077] Figure 3 The graph of shows the expected impedance behavior in the body cavity as a function of proximity. It should be noted that as the distance from the cavity wall decreases, the proximity to the cavity wall increases.

[0078] Figure 3 The graph of shows the expected shape of the impedance-proximity relationship.

[0079] In some embodiments, in vivo measurements may determine impedance values, minimum and maximum values, at the endpoints. Such minimum and maximum values may be determined for each patient, optionally by real-time accumulation of data, and determining the minimum and maximum values of the real-time data.

[0080] It should be noted that the minimum impedance value and the maximum impedance value of each electrode are specifically a function of the distance of the electrode to the reference electrode.

[0081] In some examples, the minimum impedance value and the maximum impedance value of each electrode are adjusted to determine the normalized minimum impedance value and maximum impedance value of all electrodes.

[0082] In some examples, the data points used to construct line 306 are optionally measured in vivo by measuring impedance with electrodes that move within a body cavity. All or at least some of the measurement results are used to generate line 306.

[0083] In some examples, by in vivo measurement, optionally for each patient, only the maximum impedance value and the minimum impedance value are optionally found.

[0084] In some examples, the data points used to construct line 306 are optionally measured in vivo by a plurality of electrodes that move within a body cavity, electrodes that measure impedance, and a position measurement system that optionally measures the electrode positions.

[0085] In some examples, the data points used to construct line 306 are optionally obtained from a database that includes data measured for a specific patient at a certain historical time.

[0086] In some examples, the data points used to construct line 306 are optionally obtained from a database that includes data measured for a group of patients at a certain historical time (optionally averaged).

[0087] Figure 3 Two specific levels of impedance along the Y-axis 304 are also shown.

[0088] The first specific impedance level 308 shows the impedance at which the electrode starts to contact the cavity wall and the distance to the cavity wall is close to zero. The line 306 to the left of the contact impedance is in the "no contact" impedance zone 312. In some examples, the value of the first specific impedance level 308 is determined to be a specific percentage below the maximum value of line 306.

[0089] The second specific impedance level 310 shows the impedance of the electrode that contacts and pushes against the cavity wall with a force level considered sufficient to perform ablation (if needed) using the electrode. The corresponding "contact"

[0090] zone 314 is shown, where the cavity wall is slightly pushed from the contact point due to the greater force applied to the cavity wall to create good enough contact. Outside the "contact" zone 318, the impedance flattens out to its maximum value, and this is shown by the "saturation" zone 316 and the high impedance above the level represented by 310.

[0091] Now refer to Figure 4 , which is a simplified flowchart illustration of a method according to one aspect of the present disclosure that indicates the movement of the receiving electrode of the distal end assembly relative to the tissue cavity wall.

[0092] Figure 4 The method of includes: using a distal end assembly that includes being arranged in a three-dimensional (3D) configuration

[0093] Multiple electrodes (402) on the distal end assembly, in some examples, track the position of the distal end assembly in a 3D workspace. Tracking can include tracking a position sensor at one or more of the following: a coupler, a pusher, a nose connector, a reference electrode, a strip,

[0094] an object, and a receiving electrode of the distal end assembly. Tracking potentially enables a graphical representation of the distal end assembly to be presented on a display in real time based on the tracking. The presentation can optionally include displaying the electrodes mounted on the distal end assembly;

[0095] Transmit an alternating current (AC) signal (404) between one or more reference electrodes and a plurality of receiving electrodes attached to a plurality of strips;

[0096] Calculate a plurality of impedance values (406) that vary over time based on the received signal at each of the receiving electrodes. In some examples, the impedance values can be normalized based on the different distances of the different receiving electrodes from the reference electrode.

[0097] Calculate the gradient (408) of the impedance value varying over time at each of the receiving electrodes;

[0098] Dynamically present a virtual representation of the distal end assembly within a three-dimensional workspace on a display, where the virtual representation includes a virtual representation of each of the plurality of receiving electrodes on the distal end assembly (410); and

[0099] Dynamically adjust the graphical characteristics of at least one of the plurality of receiving electrodes displayed based on the calculated gradient of the impedance varying over time (412).

[0100] In some examples, the dynamic adjustment includes presenting the receiving electrodes differently based on different values of the gradient of the impedance measured over time at the receiving electrodes. (408);

[0102] The different presentations or graphical characteristics corresponding to different values of the gradient can be achieved by different graphical characteristics, such as color coding, and / or shading, and / or blinking, and / or highlighting the display of the electrodes.

[0103] ; and

[0104] Based on the calculated gradient of the impedance varying over time to dynamically adjust the graphical characteristics of at least one of the plurality of receiving electrodes displayed (412).

[0105] In some examples, the dynamic adjustment includes presenting the receiving electrodes differently based on different values of the gradient of the impedance measured over time at the receiving electrodes.

[0106] The different presentations or graphical characteristics corresponding to different values of the gradient can be achieved by different graphical characteristics, such as color coding, and / or shading, and / or blinking, and / or highlighting the display of the electrodes.

[0107] In some cases, only two different types of graphical features are used to present the receiving electrodes: a first graphical feature when the gradient value changing over time is greater than a first positive threshold, and a different second graphical feature when the impedance gradient value changing over time is less than a second negative threshold.

[0108] The first positive threshold can be used to distinguish electrodes with greater impedance gradient values, which indicates that they are closer to the tissue cavity wall and moving towards the tissue cavity wall, and to display the closer electrodes differently from other electrodes with smaller impedance gradient values.

[0109] The second negative threshold can be used to distinguish electrodes with a negative impedance gradient value, which indicates that they are moving away from the tissue cavity wall.

[0110] In some cases, only three different types of graphical features are used to label the receiving electrodes: a first graphical feature when the gradient value changing over time is greater than a first positive threshold, a different second graphical feature when the gradient value changing over time is less than a second negative threshold, and a third graphical feature when the gradient value changing over time is between the negative threshold and the positive threshold.

[0111] In some examples, calculating multiple impedance values can include normalizing the impedance values, and calculating the spatial gradient includes using the normalized impedance values.

[0112] In some examples, the normalization can include normalizing using the previously measured maximum value and the previously measured minimum value of the impedance at each of the receiving electrodes.

[0113] Figure 4 The method provides a visual indication to guide a physician on how to manipulate a catheter along the tissue wall of a heart chamber to map the heart chamber and / or indicate how to manipulate the catheter to reach a location of interest.

[0114] Now refer to Figure 5A and Figure 5B which are views of the distal end assembly of the catheter as shown on a display, and based on a spatial gradient superimposed on the display of the expandable catheter, a direction is displayed according to one aspect of the present disclosure. Figure 2 shows all the components of the expandable basket-shaped distal end assembly 28 as shown in

[0115] Figures 5A to 5B as shown on a display 500, and in the case where these components are shown with reference numerals, they are denoted by the same reference numerals as in Figure 2 shown in Figure 2 and when these components are shown with reference numerals, they are denoted by the same reference numerals as in Figure 2 and are represented by the same reference numerals as in

[0116] Figure 5AAn arrow 502 is shown in the direction of movement of the distal end assembly 28. The arrow 502 points to the tissue wall 80.

[0117] The electrode labeled 66a moves toward the tissue wall 80 and measures an increase in impedance, such as a positive gradient over time, that is greater than a certain positive threshold. The electrode 66a faces the tissue wall and moves toward the tissue and is marked by a graphical feature, such as by a first specific color indicating an increase in impedance, or by a first specific brightness, or by some other indicatory marking.

[0118] In some examples, the physician may manipulate the catheter within the cavity before or at the start of anatomical mapping and may thus not know the depiction of the tissue wall. The displayed indication provided on the electrode 66a may assist the physician in manipulating the distal end assembly 28 toward the area of interest and / or along the tissue wall.

[0119] Figure 5B An arrow 504 is shown in the direction of movement of the distal end assembly 28. The arrow 504 points in a direction away from the cavity wall tissue 80.

[0120] The electrode labeled 66a is moving away from the cavity wall tissue 80 and is measuring a decrease in impedance, such as a negative gradient over time, that becomes more negative or less than a certain negative threshold. The electrode is shown as moving away from the tissue in a direction away from the tissue, such as by a certain specific color indicating a decrease in impedance, or by a specific brightness, or by some other indicatory marking.

[0121] Overview of the present disclosure

[0122] Example 1 :

[0123] A method of indicating movement of a receiving electrode of a distal end assembly relative to a tissue cavity wall, the method comprising:

[0124] Using a distal end assembly that includes a plurality of electrodes arranged in a three-dimensional (3D) configuration on the distal end assembly;

[0125] Transmitting an alternating current (AC) signal between one or more reference electrodes and a plurality of receiving electrodes attached to a plurality of strips;

[0126] Calculating a plurality of impedance values that vary over time based on the received signals at each of the receiving electrodes;

[0127] Calculating the gradient of the impedance values over time at each of the receiving electrodes;

[0128] Dynamically presenting a virtual representation of the distal end assembly within a three-dimensional workspace on a display, wherein the virtual representation includes a virtual representation of each of the plurality of receiving electrodes on the distal end assembly; and

[0129] Dynamically adjusting a graphical feature of at least one of the plurality of receiving electrodes displayed based on the calculated gradient of the impedance over time.

[0130] Example 2 :

[0131] The method according to embodiment 1, wherein a first graphical feature is defined for a calculated positive gradient that is higher than a defined positive threshold, and a second graphical feature is defined for a calculated negative gradient that is lower than a defined negative threshold.

[0132] Example 3 :

[0133] 3. The method according to any one of embodiments 1 to 2, wherein a third graphical feature is defined for a calculated gradient between the negative threshold and the positive threshold.

[0134] Example 4 :

[0135] The method according to any one of embodiments 1 to 3, wherein calculating the plurality of impedance values at each of the receiving electrodes includes normalizing the impedance values at each of the receiving electrodes, and calculating the impedance gradient over time includes using the normalized impedance values.

[0136] Example 5 :

[0137] The method according to embodiment 4, wherein the normalization includes normalizing using a previously measured maximum value and a previously measured minimum value of the impedance at each of the receiving electrodes.

[0138] Example 6 :

[0139] The method according to any one of embodiments 1 to 5, wherein the one or more reference electrodes include reference electrodes located on a shaft of a basket catheter.

[0140] Example 7 :

[0141] The method according to any one of embodiments 1 to 6, wherein at least one of the plurality of receiving electrodes attached to the plurality of strips includes an ablation electrode.

[0142] Example 8 :

[0143] The method according to any one of Embodiments 1 to 7, wherein the spatial position of the strip is measured by a position sensor.

[0144] Example 9 :

[0145] The method according to any one of Embodiments 1 to 8, wherein the spatial position of the receiving electrode is measured by a position sensor.

[0146] Those skilled in the art to which the present disclosure pertains will understand that although the present invention has been described in accordance with the preferred embodiments, the concepts on which the present disclosure is based can be readily used as a basis for designing other structures, systems, and processes for achieving several objects of the present disclosure.

[0147] Furthermore, it should be understood that the language and terminology used herein are for illustrative purposes and should not be considered restrictive. It should be noted that the words "comprising", "including", and "having" used throughout the appended claims should be construed to mean "including but not limited to". Unless explicitly stated to the contrary, the indefinite articles "a" and "an" as used herein in the specification and claims should be understood to mean "at least one". The phrase "and / or" as used herein in the specification and claims should be understood to mean "either or both" of the elements so combined, i.e., elements that exist combinatorially in some cases and separately in other cases. The term "each" may not be construed exclusively to refer to every and each one, and may also refer to "at least some" when technically relevant.

[0148] All patents and patent applications mentioned in this specification are hereby incorporated by reference in their entirety into this specification to the same extent as if each individual patent or patent application was specifically and independently indicated to be incorporated by reference herein. Additionally, the citation or identification of any reference in this patent application should not be construed as an admission that such reference is available as prior art to the present disclosure.

[0149] Therefore, it is important that the scope of the present disclosure should not be construed as being limited by the exemplary embodiments set forth herein. Other variations are possible within the scope of the present disclosure as defined by the appended claims. Other combinations and sub - combinations of features, functions, elements, and / or characteristics may be claimed by amending the present claims or by filing new claims in this application or related applications. Whether for different combinations or for the same combination, these amendments or new claims, whether different, broader, narrower, or the same in scope as the original claims, are considered to be included within the subject matter of this specification.

Claims

1. A method for indicating movement of a receiving electrode of a distal end assembly relative to a tissue cavity wall, the method comprising: using a distal end assembly including a plurality of electrodes arranged in a three-dimensional (3D) configuration on the distal end assembly; transmitting an alternating current (AC) signal between one or more reference electrodes and a plurality of receiving electrodes attached to a plurality of strips; calculating a plurality of impedance values that vary over time based on received signals at each of the receiving electrodes; calculating a gradient of the impedance values that vary over time at each of the receiving electrodes; dynamically presenting a virtual representation of the distal end assembly within a three-dimensional workspace on a display, wherein the virtual representation includes a virtual representation of each of the plurality of receiving electrodes on the distal end assembly; and dynamically adjusting a graphical feature of at least one of the plurality of receiving electrodes displayed based on the calculated gradient of the impedance over time.

2. The method according to claim 1, wherein Defining a first graphical feature for a calculated positive gradient that is above a defined positive threshold and a second graphical feature for a calculated negative gradient that is below a defined negative threshold.

3. The method according to any one of claims 1 to 2, wherein, Defining a third graphical feature for a calculated gradient between the negative threshold and the positive threshold.

4. The method according to any one of claims 1 to 3, wherein Calculating the plurality of impedance values at each of the receiving electrodes includes normalizing the impedance values at each of the receiving electrodes, and calculating the gradient of the impedance that varies over time includes using the normalized impedance values.

5. The method according to claim 4, wherein The normalization includes normalizing using a previously measured maximum value and a previously measured minimum value of the impedance at each of the receiving electrodes.

6. The method according to any one of claims 1 to 5, wherein The one or more reference electrodes include reference electrodes located on a guide rod of a basket catheter.

7. The method according to any one of claims 1 to 6, wherein At least one of the plurality of receiving electrodes attached to the plurality of strips includes an ablation electrode.

8. The method according to any one of claims 1 to 7, wherein The spatial position of the strips is measured by a position sensor.

9. The method according to any one of claims 1 to 8, wherein, The spatial position of the receiving electrodes is measured by a position sensor.

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