Dual-choice graphical presentation of electrophysiological parameters

Abstract

The present invention is entitled "Dual-selection graphical presentation of electrophysiological parameters". The present invention provides a medical device, which includes a probe configured to be inserted into a patient's body. The probe includes electrodes configured to contact tissue within the body. The device also includes a display screen, a position tracking system configured to collect position coordinates of the electrodes, and a processor. The processor is configured to collect electrophysiological signals from the electrode group in a sequence of time intervals, extract electrophysiological parameters from the signals, and for each time interval, calculate a consistency measure of the parameters extracted from the signals. The processor is further configured to render a three-dimensional map of the tissue to the display screen, while superimposing on the map a visual indication of the extracted parameters whose consistency measures meet the consistency criteria, and automatically discarding from the map parameters whose consistency measures do not meet the criteria.

Description

Technical Field

[0001] The present invention relates generally to electrophysiological measurements, and in particular to apparatus and methods for automatic mapping of electrophysiological parameters. Background Art

[0002] An electrophysiological (EP) map of a patient's tissue is generated by positioning one or more electrodes over an area of ​​tissue; acquiring the EP signal in that area; and then repeating the process for different areas. EP parameters are extracted from the EP signal in each measured area and then displayed on an image of the tissue. Summary of the invention

[0003] Embodiments of the present invention described below provide improved methods and apparatus for mapping electrophysiological parameters.

[0004] Therefore, according to an embodiment of the present invention, a medical device is provided, which includes a probe configured to be inserted into a patient's body. The probe includes a plurality of electrodes configured to contact tissue in the body in a time interval sequence. The device also includes a display screen, a position tracking system configured to collect the position coordinates of the electrodes in the body, and a processor.

[0005] The processor is configured to acquire corresponding electrophysiological signals from the electrode group at each time interval in the sequence when the electrodes contact the area at corresponding positions within the area of ​​tissue, to extract corresponding electrophysiological parameters from the corresponding electrophysiological signals acquired by the electrodes in the group at each time interval, and for each time interval, to calculate a corresponding consistency measure between the corresponding electrophysiological parameters extracted from the electrophysiological signals acquired by the electrodes in the group during the time interval. The processor is further configured to render a three-dimensional (3D) map of the tissue to a display screen, while superimposing on the map a visual indication of the extracted electrophysiological parameters at the corresponding positions of the electrodes at the time intervals where the corresponding consistency measures meet a predefined consistency criterion in response to the position coordinates, and automatically discard from the map the electrophysiological parameters extracted at the time intervals where the corresponding consistency measures do not meet the predefined consistency criterion.

[0006] In some embodiments, the electrophysiological parameter includes a local activation time (LAT) in the patient's heart, and the consistency metric indicates a change in the LAT. In one embodiment, the consistency metric includes a peak-to-peak change in the LAT at any given time interval, and the consistency criterion requires that the peak-to-peak change in the LAT does not exceed a predefined limit.

[0007] Alternatively or in addition, the electrophysiological parameter comprises an electrophysiological voltage, and the consistency measure indicates a change in the electrophysiological voltage. In one embodiment, the consistency measure comprises a peak-to-peak change in the electrophysiological voltage at any given time interval, and the consistency criterion requires that the peak-to-peak change in the electrophysiological voltage does not exceed a predefined limit.

[0008] In another embodiment, the 3D map is rendered in a background color, and the visual indication includes other colors superimposed on the background color at corresponding locations to indicate the values ​​of the extracted electrophysiological parameters.

[0009] According to an embodiment of the present invention, a method for electrophysiological mapping is also provided. The method includes: when the electrode group on the probe contacts the area of ​​tissue in the patient's body, collecting corresponding electrophysiological signals from the electrode group on the probe in a time interval sequence, and collecting the position coordinates of the electrode group. Extracting corresponding electrophysiological parameters from the corresponding electrophysiological signals collected by the electrodes in the group at each time interval in the sequence, and for each time interval, calculating the corresponding consistency measure between the corresponding electrophysiological parameters extracted from the electrophysiological signals collected by the electrodes in the group during the time interval. The method also includes: displaying a three-dimensional (3D) mapping map of the tissue, while superimposing on the mapping map in response to the position coordinates a visual indication of the extracted electrophysiological parameters at the corresponding position of the time interval where the corresponding consistency measure meets the predefined consistency standard, and automatically discarding from the mapping the electrophysiological parameters extracted at the time interval where the corresponding consistency measure does not meet the predefined consistency standard.

[0010] The present invention will be more fully understood through the following detailed description of embodiments of the present invention in conjunction with the accompanying drawings, in which: BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 is a schematic illustration of a medical device for mapping EP parameters in a patient's heart according to an embodiment of the present invention;

[0012] Figure 2 is a flow chart schematically illustrating a method for automatic EP mapping according to an embodiment of the present invention; and

[0013] Figure 3 is a schematic diagram of an electroanatomical map according to an embodiment of the present invention. DETAILED DESCRIPTION

[0014] Overview

[0015] Generating an electrophysiological (EP) map of a patient's tissue involves positioning one or more electrodes over an area of ​​the tissue, acquiring signals from that area, and then repeating the process for different areas. When a small number of electrodes is used, the process generates an accurate map of EP parameters extracted from those signals because the physician can observe the acquired signals and only accept "good" signals (as judged by the physician) for the map. Good signals are generally generated only when the electrodes are in good contact with the tissue. However, using a small number of electrodes has the disadvantage of taking a long time to map.

[0016] For catheters with a large number of electrodes, mapping time is reduced, but accuracy is reduced because the physician cannot correctly detect all of the signals generated simultaneously in the available time. The task of accepting good signals (and rejecting other signals) can be facilitated by presenting the physician with the results of the analysis of the signals, i.e., the values ​​of the EP parameters across the measurement area. (For the sake of brevity, the "values ​​of the EP parameters" will be referred to simply as "EP parameters" in the following description.) The task can be further facilitated by presenting these values ​​in graphical form, such as a map of the values. However, the physician still needs to use his / her subjective judgment to accept or reject the analyzed results, and there is inherent variability in acceptance due to subjectivity. In addition, requiring the physician to judge the quality of these results will further consume his / her time and attention in the mapping procedure, especially when a large number of electrodes are used.

[0017] Embodiments of the invention described herein address these problems by providing a medical device comprising a probe, a display screen, a position tracking system, and a processor. A probe comprising a plurality of electrodes is inserted into the patient's body such that the electrode set contacts an area of ​​tissue within the body. The electrode set may include all electrodes on the probe or a specific subset of electrodes. (For example, the set may include a specific area of ​​myocardial tissue, typically about 1 cm, of a total of 120 electrodes on a basket catheter.) 2 Up to 10cm 2 ) When the electrodes contact the tissue, the processor collects EP signals from the electrodes in a time interval sequence such as a heartbeat sequence. At the same time, the position tracking system collects the position coordinates of the electrodes.

[0018] For each time interval, the processor extracts the corresponding EP parameter from the signal and calculates a consistency measure of the values ​​of the EP parameter on the electrodes in the group. For simplicity, the EP parameters extracted from the electrode group of the area contacting the tissue at a given time interval will be referred to as an "EP parameter set". The processor renders a three-dimensional (3D) map of the tissue to a display screen, while superimposing on the map a visual indication of the EP parameter set at the time point at which the consistency measure meets the predefined consistency criteria, such as a color representing the parameter value. The processor automatically discards from the map EP parameters whose corresponding consistency measures do not meet the predefined criteria.

[0019] The method facilitates automatic presentation of a map of valid EP parameters without having to rely on a physician's subjective and time-consuming assessment of EP signals or parameters.

[0020] In an embodiment disclosed herein, the processor displays a 3D map of the chamber of the heart for which EP parameters are being mapped. The 3D map is presented in a neutral tone, such as gray. EP parameters may include, for example, local activation time (LAT) measured in the myocardium or bipolar or unipolar maximum voltage. LAT is the time interval between a reference time determined, for example, from a surface ECG or intracardiac electrogram and the time of a local depolarization event. Other available scalar functions of physiological parameters may be calculated and displayed, and then superimposed on a combined display of LAT (such as pseudocolor) and / or propagation velocity (such as arrows). One such available scalar function is the voltage range measured at each sampling point (displayed as pseudocolor): an abnormally low range is diagnostic of scar tissue, and conduction velocity on scar tissue may be displayed as an arrow. For example, LAT can be determined manually or automatically by marking one or more of the following: (a) the maximum negative slope (-dV / dt) of the voltage recorded unipolarly; (b) the maximum absolute voltage recorded bipolarly; (c) the maximum absolute slope dV / dt recorded bipolarly; or (d) the minimum voltage recorded bipolarly. (Methods for automatically calculating LAT are known in the art, for example, in the method produced by Biosense Webster Inc., Irvine, California.) system.)

[0021] During the measurement process in the heart, the processor extracts a set of EP parameters in each of several (e.g., 3 to 7) heartbeats from all electrodes in contact with the tissue. (Alternatively, the time intervals measured may be independent of the heartbeat.) Since the area over which the electrodes contact the tissue is small compared to the chambers of the heart, it is expected that the EP parameters within a set will differ from each other by only a small amount. Therefore, large fluctuations between EP parameters in a set are an indication of improper EP signal acquisition. The cause of improper EP signal acquisition may be, for example, poor contact between one or more electrodes and the tissue. In order to identify and reject improperly acquired EP signals, the processor calculates a consistency measure within each EP parameter set. The consistency measure may be, for example, the peak-to-peak variation within the EP parameter set across the electrode group.

[0022] The processor rejects EP parameter sets whose consistency measures do not meet the predefined consistency criteria, while it accepts EP parameters that meet the consistency criteria. The processor updates the 3D map by superimposing an overlay on the map to indicate the values ​​of the accepted EP parameter sets. The indication may be, for example, a color code, where the lowest value of the EP parameter is represented by blue, the highest value by red, and intermediate values ​​by colors of the visible spectrum between blue and red. When several EP parameter sets are accepted in a given area, the processor may superimpose the 3D map with, for example, an average value of the accepted sets. Alternatively, the processor may superimpose the accepted sets on the map one by one, or superimpose it with only one of the accepted sets.

[0023] System Description

[0024] Figure 1 is a schematic diagram of a medical device 20 for mapping EP parameters in a heart 26 of a patient 28, in accordance with an embodiment of the present invention.

[0025] A physician 30 navigates a basket catheter 40, shown in detail in inset 45, to a target location in the heart 26 of a patient 28 by manipulating the shaft 22 and / or deflection of the slave sheath 23 using a manipulator 32 near the proximal end of the catheter. In the embodiment seen in inset 25, the physician 30 uses the catheter 40 to perform electroanatomical mapping of a cardiac chamber. EP signals are acquired from tissue using a group of electrodes 48 on the basket catheter 40 that contact the tissue in a region 46, as described in further detail below. When a basket catheter is used, the electrode group is typically a smaller subset of the total number of electrodes 48, such as 20 electrodes out of a total of 120 electrodes.

[0026] Catheter 40 is inserted into sheath 23 in a collapsed configuration, and only after the catheter exits sheath 23 does the catheter expand to its intended functional shape, as shown in inset 45. By containing catheter 40 in a collapsed configuration, sheath 23 also serves to minimize vascular trauma on its way to the target site.

[0027] The basket catheter 40 incorporates a magnetic sensor 50A (see inset 45) at the distal edge of the shaft 22 (i.e., at the proximal edge of the basket catheter 40). Typically, although not necessarily, the sensor 50A is a three-axis sensor (TAS) including three microcoils oriented in different directions. In the illustrated embodiment, a second magnetic sensor 50B is incorporated into the distal edge of the basket catheter. The sensor 50B can be, for example, a single-axis sensor (SAS) or a three-axis sensor (TAS). Alternatively, the catheter 40 can include other types of magnetic sensors at these locations or other locations.

[0028] The catheter 40 also includes a plurality of expandable spines 55, which may be mechanically flexible, and a plurality of electrodes 48 (e.g., 120 electrodes in total) coupled to each expandable spine. The electrodes 48 are configured to contact the tissue of the patient 28 to sense EP signals. The magnetic sensors 50A and 50B and the electrodes 48 are connected to various processing circuits in the console 24 via wires passing through the shaft 22.

[0029] Alternatively, device 20 may include other types of catheters, as well as other types of electrode arrays, such as an inflatable balloon catheter having electrodes 48 on an outer surface.

[0030] The medical device 20 includes a magnetic sensing subsystem for determining the position and orientation of the basket catheter 40, and thereby the position of the electrodes 48. The patient 28 is placed in a magnetic field generated by a pad containing a magnetic field generator coil 42, which is driven by a tracking module 43 in the console 24. The magnetic field generated by the coil 42 induces electrical signals in the sensors 50A and 50B that indicate the position and / or orientation of the sensors. The signals from the sensors 50A and 50B are transmitted back to the tracking module 43, which converts the signals into corresponding digital inputs to the processor 41. The processor 41 uses these inputs to calculate the position and orientation of the basket catheter 40, and thereby finds the corresponding position of each of the electrodes 48.

[0031] Methods of position and / or orientation sensing using external magnetic fields and magnetic sensors such as sensor 50A and sensor 50B are implemented in various medical applications, such as in the Magnetic Sensors available from Biosense Webster, Inc. (Irvine, California). Such methods are described in detail in U.S. Patents 5,391,199, 6,690,963, 6,484,118, 6,239,724, 6,618,612, and 6,332,089, PCT Patent Publication WO 96 / 05768, and U.S. Patent Application Publications 2002 / 0065455A1, 2003 / 0120150A1, and 2004 / 0068178A1, the disclosures of which are incorporated herein by reference in their entirety and copies are provided in the Appendix.

[0032] Alternatively or in addition, device 20 may use other position sensing methods to find the position of electrode 48. For example, processor 41 may map the position of electrode 48 by measuring the impedance between electrode 48 and body surface electrode 49, which is placed on the chest of patient 28 and connected to console 24 by lead 39.

[0033] Processor 41 additionally receives electrophysiological signals via electrical interface 44 and uses the information contained in these signals along with the coordinates provided by magnetic sensors 50A and 50B to construct an electroanatomical map 31 of the chamber of heart 26 in which catheter 40 is located. During and / or after the procedure, processor 41 may render electroanatomical map 31 to display screen 27 (on a Figure 3 Detailed description in ).

[0034] The processor 41 is typically programmed in software to perform the functions described herein. The software may be downloaded to the computer in electronic form over a network, for example, or it may alternatively or additionally be provided and / or stored on a non-transitory tangible medium (such as magnetic storage, optical storage, or electronic storage). Specifically, the processor 41 runs a dedicated algorithm that enables the processor to perform the steps disclosed in the present invention, as described below.

[0035] Figure 1 The exemplary illustrations shown are chosen purely for the sake of conceptual clarity. Figure 1 Only the elements related to the technology disclosed in the present invention are shown. The medical device 20 generally includes additional modules and elements that are not directly related to the technology disclosed in the present invention and are therefore not directly related to the technology disclosed in the present invention. Figure 1 The elements of medical device 20 and the methods described herein may further be applied to, for example, control ablation of tissue of heart 26 .

[0036] Measurement and display of EP parameters

[0037] Figure 2 2 is a flow chart 200 schematically illustrating an automated process for EP mapping according to an embodiment of the present invention. In this method, EP parameters from regions 46 are included in the map only if they meet certain consistency criteria. The embodiment shown in flow chart 200 refers to an example of acquiring EP signals from a chamber of heart 26 (see Figure 1 ). In alternative embodiments, EP parameter values ​​may be acquired using other types of mapping devices, not only from the heart, but also from other organs and tissues, which will be apparent to those skilled in the art after reading this specification.

[0038] The process shown in flowchart 200 begins at start step 202. In a map generation step 204, a uniform gray (or other suitable background color) 3D map of the ventricle is generated by processor 41 and rendered on display screen 27. The 3D map is generated, for example, from an image of heart 26 previously stored in the processor, or based on position measurements acquired by a catheter. Alternatively, the 3D map may be generated while displaying EP parameters. In a catheter positioning step 206, physician 30 positions catheter 40 in heart 26 so that the group of electrodes 48 is in contact with myocardial tissue in region 46 of the heart chamber. In an acquisition step 208, processor 41 receives signals from the group of electrodes 48 during a single time interval (such as a single heartbeat). In a tracking step 209, processor 41 receives signals from tracking module 43 and calculates corresponding position coordinates of electrodes 48. In an extraction step 210, processor 41 extracts a set of EP parameters from the signals received in acquisition step 208.

[0039] In a consistency calculation step 212, the processor 41 calculates a consistency measure for the set of EP parameters extracted in the extraction step 210. The consistency measure, as well as the consistency criterion, is defined in this embodiment based on the peak-to-peak variation of the EP parameter in a given set. For example, when the EP parameter calculated in step 210 is the local activation time (LAT), the consistency criterion may adopt a range of ±10ms, that is, if the LATs in the set are within 20ms of each other, they are considered to meet the consistency criterion. For another example, when the EP parameter is a bipolar or unipolar maximum voltage in the signal sensed by the electrode 48, the consistency criterion may adopt a range of 20mV, so that the measured maximum voltage within this range is considered to meet the consistency criterion. Alternatively, a larger or smaller range of the parameter may be considered as the consistency criterion.

[0040] Alternatively, other kinds of consistency criteria may be applied. For example, the processor 41 may calculate the mean values ​​of the considered EP parameters and the variance of the parameters of the heartbeat sequence and may define the consistency criterion according to the maximum acceptable variance.

[0041] In a first decision step 214, processor 41 compares the consistency measure calculated in step 212 with a predefined consistency criterion. If the consistency measure meets the consistency criterion, processor 41 includes the EP parameter set in the accepted set in an inclusion step 216. If the consistency measure does not meet the criterion, processor 41 discards the EP parameter set in a discard step 218.

[0042] From both the included step 216 and the discarding step 218, the process continues to a second decision step 220, where the processor 41 determines whether to acquire more EP parameter sets from the current region 46 based on preset criteria. Additional acquisitions may be required if, for example, the consistency metric does not meet the consistency criteria for any of the EP parameter sets acquired from the current region 46. Alternatively or in addition, additional acquisitions may be required in order to average a large number of accepted sets. When more acquisitions are required, the process returns to step 208.

[0043] When no more acquisitions are needed, the EP parameter sets collected in step 216 may optionally be averaged in an averaging step 222. Alternatively, the averaging step 222 may be bypassed and only one of the accepted EP parameter sets may be selected for output. In a display step 224, the resulting representation of the EP parameters (averaged or not) is superimposed on the 3D map. In the display step 224, based on the position coordinates received in the tracking step 209, the processor 41 displays the EP parameters, for example, by applying corresponding color codes to appropriate areas of the 3D map generated in step 204. The color coding may include, for example, displaying the lowest value of the EP parameter as blue, the highest value as red, and displaying intermediate values ​​between the lowest and highest values ​​in the same order as the order of colors in the visible light spectrum. However, other color coding schemes such as those known in the art and other types of shading or symbols may alternatively be used.

[0044] After the display step 224, the process continues to a third decision step 226, where the physician 30 decides whether to include an additional zone in the mapping. If the decision is positive, the physician 30 moves the catheter 40 to the new zone 46 in step 206, and the process continues from there, as described above. When the physician 30 determines that the mapping is complete, the process ends in an end step 228.

[0045] Figure 3 is a schematic diagram of an electroanatomical map 31 according to an embodiment of the present invention. Figure 2 ), the 3D map 300 is initially displayed in a neutral color, such as gray, on the display screen 27. When the EP parameters acquired by the basket catheter 40 meet the applicable consistency criteria, the 3D map 300 is displayed in a neutral color, such as gray. Figure 2 The colored overlay 302 is superimposed on the 3D map 300 by the method.

[0046] Although the above-described embodiments relate to the measurement of EP parameters in heart 26, in alternative embodiments, the described methods of automatically accepting or rejecting EP parameters may be applied to other tissues of the body of patient 28. Furthermore, in alternative embodiments, more than one type of EP parameter may be measured and displayed simultaneously.

[0047] It should therefore be understood that the embodiments described above are cited by way of example, and that the present invention is not limited to what is specifically shown and described above. On the contrary, the scope of the present invention includes combinations and sub-combinations of the various features described above, as well as variations and modifications thereof, which should occur to those skilled in the art upon reading the above description, and which are not disclosed in the prior art.

Claims

1. A medical device, comprising: a probe configured for insertion into a patient's body and comprising a plurality of electrodes configured to contact tissue within the body in a time-spaced sequence; Display screen; a position tracking system configured to collect position coordinates of the electrodes within the body; as well as A processor, the processor being configured to: acquiring corresponding electrophysiological signals from the set of electrodes at each time interval in the sequence while the electrodes contact the region of tissue at corresponding locations within the region; extracting corresponding electrophysiological parameters from the corresponding electrophysiological signals collected by the electrodes in the group at each time interval; For each time interval, calculating a corresponding consistency measure between the corresponding electrophysiological parameters extracted from the electrophysiological signals acquired by the electrodes in the group during the time interval, wherein if the variation range of the corresponding electrophysiological parameters is within the range of a predefined consistency standard, then the corresponding consistency measure is considered to satisfy the predefined consistency standard, otherwise, then the corresponding consistency measure is considered to not satisfy the predefined consistency standard; and A three-dimensional 3D map of the tissue is rendered to the display screen, and a visual indication of the electrophysiological parameters extracted at the corresponding positions of the electrodes at the time intervals at which the corresponding consistency measures satisfy the predefined consistency criteria is superimposed on the 3D map in response to the position coordinates, and the electrophysiological parameters extracted at the time intervals at which the corresponding consistency measures do not satisfy the predefined consistency criteria are automatically discarded from the 3D map.

2. The medical device of claim 1, wherein the electrophysiological parameter comprises a local activation time (LAT) in the patient's heart, and the consistency measure indicates a change in the LAT.

3. The medical device of claim 2, wherein the consistency metric comprises a peak-to-peak variation of the LAT at any given time interval, and the consistency criterion requires that the peak-to-peak variation of the LAT does not exceed a predefined limit. 4 . The medical device of claim 1 , wherein the electrophysiological parameter comprises an electrophysiological voltage, and the consistency measure indicates a variation in the electrophysiological voltage.

5. The medical device of claim 4, wherein the consistency metric comprises a peak-to-peak variation of the electrophysiological voltage at any given time interval, and the consistency criterion requires that the peak-to-peak variation of the electrophysiological voltage does not exceed a predefined limit. 6 . The medical device of claim 1 , wherein the 3D map is rendered in a background color, and the visual indication comprises other colors superimposed on the background color at the corresponding locations to indicate the values ​​of the extracted electrophysiological parameters.

Images