Selective Graphical Display of Electrophysiological Parameters

Abstract

To provide a medical apparatus.SOLUTION: A medical apparatus includes a probe configured for insertion into a body of a patient. The probe includes electrodes configured to contact tissue within the body. The apparatus further includes a display screen, a position-tracking system configured to acquire position coordinates of the electrodes, and a processor. The processor is configured to acquire electrophysiological signals from a group of the electrodes in a sequence of time intervals, extract electrophysiological parameters from the signals, and compute, for each time interval, a measure of consistency of the parameters extracted from the signals. The processor is further configured to display on the display screen a three-dimensional map of the tissue while superimposing on the map a visual indication of the extracted parameters for which the measure of consistency satisfied a consistency criterion, and automatically discard from the map the parameters for which the measure of consistency did not satisfy the consistency criterion.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention generally relates to electrophysiological measurements, and more particularly to an apparatus and method for automatically mapping electrophysiological parameters.

Background Art

[0002] An electrophysiological (EP) map of a patient's tissue is generated by placing one or more electrodes on a region of the tissue, acquiring the EP signals of this region, and then repeating this process for different regions. EP parameters are extracted from the EP signals in each region of the measurement and then displayed on an image of the tissue.

Summary of the Invention

Means for Solving the Problems

[0003] Embodiments of the present invention described hereinafter provide an improved method and apparatus for mapping electrophysiological parameters.

[0004] Accordingly, embodiments of the present invention provide a medical device including a probe configured to be inserted into a patient's body. The probe includes a plurality of electrodes configured to contact tissue within the body at a series of time intervals. The device further includes a display screen, a position tracking system configured to acquire the position coordinates of the electrodes inside the body, and a processor.

[0005] The processor is configured to obtain individual electrophysiological signals from a group of electrodes at a series of time intervals while the electrodes are in contact with a site of tissue and at individual locations within the site, extract individual electrophysiological parameters from the individual electrophysiological signals obtained at each time interval by the electrodes within the group, and calculate individual coherence measures from among the individual electrophysiological parameters extracted from the electrophysiological signals obtained by the electrodes within the group during the time interval, at each time interval. The processor is further configured to display the map on a display screen while overlaying a visual representation of the extracted electrophysiological parameters at the individual positions of the electrodes of the time interval on a three-dimensional (3D) map of the tissue in response to the position coordinates, where the individual coherence measures meet a predetermined coherence criterion, and to automatically discard from the map the electrophysiological parameters extracted during the time interval where the individual coherence measures do not meet the predetermined coherence criterion.

[0006] In some embodiments, the electrophysiological parameter includes the local activation time (LAT) in the patient's heart, and the coherence measure indicates the variation of the LAT. In one embodiment, the coherence measure includes the peak-to-peak variation of the LAT at any given time interval, and this coherence criterion requires that the peak-to-peak variation of the LAT does not exceed a predetermined threshold value.

[0007] Alternatively or in addition, the electrophysiological parameter includes the electrophysiological voltage, and the coherence measure indicates the variation of the electrophysiological voltage. In one embodiment, the coherence measure includes the peak-to-peak variation of the electrophysiological voltage at any given time interval, and this coherence criterion requires that the peak-to-peak variation of the electrophysiological voltage does not exceed a predetermined threshold value.

[0008] In yet another embodiment, the 3D map is displayed in a background color, and the visual representation includes other colors overlaid on the background color at the individual positions to indicate the values of the extracted electrophysiological parameters.

[0009] According to an embodiment of the present invention, a method of electrophysiological mapping is also provided. The method includes obtaining individual electrophysiological signals from a group of electrodes on a probe during a series of time intervals while the electrodes are in contact with a tissue site within a patient's body, and obtaining position coordinates of the group of electrodes. Individual electrophysiological parameters are extracted from the individual electrophysiological signals obtained by the electrodes in the group for each of the series of time intervals, and individual coherence measures are calculated from among the individual electrophysiological parameters extracted from the electrophysiological signals obtained by the electrodes in the group during the time interval for each time interval. The method includes displaying a map while overlaying a visual representation of the extracted electrophysiological parameters at individual positions within the time interval, where the individual coherence measures meet a predetermined coherence criterion, onto a three-dimensional (3D) map of the tissue in response to the position coordinates, and further includes automatically discarding from the map the electrophysiological parameters extracted during the time interval where the individual coherence measures do not meet the predetermined coherence criterion.

[0010] The present invention will be more fully understood by considering the following modes for carrying out the invention in conjunction with the drawings.

Brief Description of the Drawings

[0011]

Figure 1

Figure 2

Figure 3

Modes for Carrying Out the Invention

[0012] General Outline Generating an electrophysiological (EP) map of a patient's tissue involves placing one or more electrodes on a tissue region, acquiring signals from this region, and then repeating this process for different regions. When a small number of electrodes are used, this process can generate an accurate map of EP parameters extracted from these signals because the physician can observe the acquired signals and approve only the "good" signals (as determined by the physician) for inclusion in the map. Good signals are typically generated only when the electrodes are in good contact with the tissue. However, using a small number of electrodes has the drawback of taking a long time for mapping.

[0013] In the case of a catheter with a large number of electrodes, the mapping time is reduced, but the accuracy decreases because it is impossible for the physician to properly scrutinize all the simultaneously occurring signals within the available time. The task of approving good signals (and rejecting others) can be facilitated by presenting the analysis results of the signals to the physician, that is, by displaying the values of the EP parameters across the entire measurement region. (For the sake of brevity, the "values of the EP parameters" will be simply referred to as "EP parameters" in the following description.) This task can be further facilitated by presenting these values in a graphical format such as a map of these values. However, it is still necessary for the physician to use their subjective judgment, which involves an inherent variability in approval due to subjectivity, in approving or rejecting the analysis results. Furthermore, asking the physician to determine the quality of these results will impose an additional burden on the physician in terms of time and attention, especially when a large number of electrodes are used during the mapping procedure.

[0014] Embodiments of the present invention described herein address these problems by providing a medical device comprising a probe, a display screen, a position tracking system, and a processor. The probe comprising a plurality of electrodes is inserted into a patient's body such that a group of electrodes contacts a site of tissue within the body. The group of electrodes may include all of the electrodes on the probe, or a particular subset of the electrodes. (For example, the group may include 20 electrodes that contact a particular site of myocardial tissue, typically a site about 1 - 10 cm 2 in extent, out of a total of 120 electrodes on a basket catheter.) While the electrodes are in contact with the tissue, the processor acquires EP signals from the electrodes at a series of time intervals, such as a series of heartbeats. Simultaneously, the position tracking system acquires the position coordinates of the electrodes.

[0015] At each time interval, the processor extracts individual EP parameters from the signals and calculates a measure of consistency of the values of the EP parameters across the electrodes in the group. For the sake of brevity, the EP parameters extracted at a given time interval from the group of electrodes in contact with the site of tissue are referred to as a "set of EP parameters". The processor displays the map on the display screen while overlaying a visual representation, such as a color representing the parameter value, of the set of EP parameters for each point in time for which the measure of consistency meets a predetermined consistency criterion, on a three-dimensional (3D) map of the tissue. The processor automatically discards EP parameters from the map for which the individual measure of consistency does not meet the predetermined criterion.

[0016] This approach facilitates the automatic display of a map of valid EP parameters without relying on a subjective and time-consuming evaluation of the EP signals or parameters by a physician.

[0017] In the disclosed embodiments, the processor displays a 3D map of the cardiac chamber to which the EP parameters are mapped. The 3D map is displayed in an intermediate color tone such as gray. The EP parameters can include, for example, local activation time (LAT) measured in the muscular layer, or bipolar maximum voltage or unipolar maximum voltage. LAT is, for example, the time interval between a reference time determined from an ECG on the body surface or an intracardiac electrogram and the time of a local depolarization event. Other useful scalar functions of physiological parameters can be calculated and displayed and overlaid on a display that combines LAT (as a pseudocolor) and / or propagation speed (as an arrow). One such useful scalar function is the range of voltages measured at each sampling point (displayed as a pseudocolor) (an abnormally low range indicates symptoms of scar tissue), on top of which the conduction speed can be displayed as an arrow. LAT can be determined manually or automatically by marking one or more of (a) the maximum negative gradient (-dV / dt) of the voltage of a unipolar recording, (b) the maximum absolute voltage of a bipolar recording, (c) the maximum absolute gradient dV / dt of a bipolar recording, or (d) the minimum voltage of a bipolar recording. (For example, methods for automatic calculation of LAT as implemented in the CARTO® system manufactured by Biosense Webster Inc. (Irvine, California) are known in the art.)

[0018] During the measurement process in the heart, the processor extracts a set of EP parameters for each of several (e.g., 3 to 7) heartbeats from all electrodes in contact with the tissue. (Alternatively, the time interval for measurement may be independent of the heartbeat.) Since the site where the electrode contacts the tissue is small compared to the heart chamber, the EP parameters within the set are expected to differ from each other only slightly. Thus, a large variation between the EP parameters of the set indicates inappropriate acquisition of the EP signal. The reason for inappropriate EP signal acquisition can be, for example, insufficient contact between one or more electrodes and the tissue. To identify and reject inappropriately acquired EP signals, the processor calculates a measure of consistency within each set of EP parameters. The measure of consistency may be, for example, the variation between peaks within a set of EP parameters across a group of electrodes.

[0019] The processor rejects sets of EP parameters for which the measure of consistency does not meet a predetermined consistency criterion, while approving EP parameters that meet the consistency criterion. The processor updates the 3D map by overlaying an overlay on the map to show the values of the approved sets of EP parameters. This display can be, for example, color-coded, in which case the lowest value of the EP parameter is blue, the highest value is red, and the intermediate values are represented by colors in the visible spectrum between blue and red. When several sets of EP parameters are approved at a given site, the processor may overlay the 3D map, for example, with the average value of the approved sets. Alternatively, the processor may alternately overlay the approved sets on the map or overlay it with only one of the approved sets.

[0020] Description of the System FIG. 1 is a schematic depiction of a medical device 20 for mapping EP parameters in the heart 26 of a patient 28, according to an embodiment of the present invention.

[0021] Physician 30 navigates the basket catheter 40, as seen in detail in insertion view 45, to a target position in the patient 28's heart 26 by operating the shaft 22 using deflection from the remote manipulator 32 and / or the sheath 23 near the proximal end of the catheter. In the embodiment seen in insertion view 25, physician 30 uses the catheter 40 to perform electroanatomical mapping of the heart chamber. EP signals are obtained from the tissue using a group of electrodes 48 on the basket catheter 40 in contact with the tissue at site 46, as described in further detail below. When a basket catheter is used, the group of electrodes is generally a smaller subset of the total number of electrodes 48, e.g., 20 out of a total of 120 electrodes.

[0022] The catheter 40 is inserted in a folded configuration from the sheath 23 as shown in insertion view 45, and the catheter expands to its intended functional shape only after it exits the sheath 23. The sheath 23 also serves to minimize vascular trauma during the journey to the target position by constraining the catheter 40 to a folded configuration.

[0023] The basket catheter 40 incorporates a magnetic sensor 50A, as seen in insertion view 45, at the distal edge of the shaft 22 (i.e., the proximal edge of the basket catheter 40). Usually, but not necessarily, the sensor 50A is a triple-axis sensor (TAS) and includes three small coils oriented in different directions. In the illustrated embodiment, a second magnetic sensor 50B is incorporated at the distal edge of the basket catheter. The sensor 50B may be, for example, a single-axis sensor (SAS) or a triple-axis sensor (TAS). Alternatively, the catheter 40 may include other types of magnetic sensors at these or other locations.

[0024] Catheter 40 further includes a plurality of expandable spines 55 that can be mechanically flexible, and a plurality of electrodes 48, such as a total of 120 electrodes, are coupled to each of these spines. The electrodes 48 are configured to contact the tissue of patient 28 in order to detect EP signals. The magnetic sensors 50A and 50B and the electrodes 48 are connected by wires that are drawn along the shaft 22 to various processing circuits in the console 24.

[0025] Alternatively, the device 20 may comprise other types of catheters, including other types of electrode arrays, such as an expandable balloon catheter having electrodes 48 on its outer surface.

[0026] The medical device 20 includes a magnetic detection subsystem for determining the position and orientation of the basket catheter 40 and the position of the electrodes 48 thereby. The patient 28 is placed in a magnetic field generated by a pad including a magnetic field generating coil 42 driven by a tracking module 43 in the console 24. An electrical signal is generated in the sensors 50A and 50B by the magnetic field generated by the coil 42. These 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, and this module converts this signal into a digital input value corresponding to the processor 41. The processor 41 uses these input values to calculate the position and orientation of the basket catheter 40, and thus finds the individual position of each of the electrodes 48.

[0027] Methods for detecting the position and / or orientation of an external magnetic field and magnetic sensors such as sensors 50A and 50B are performed in various medical applications, for example, in the CARTO® system available from Biosense Webster, Inc. (Irvine, California). Such methods are described in detail in U.S. Patent Nos. 5,391,199, 6,690,963, 6,484,118, 6,239,724, 6,618,612, and 6,332,089, International Publication No. 96 / 05768, and U.S. Patent Application Publication Nos. 2002 / 0065455(A1), 2003 / 0120150(A1), and 2004 / 0068178(A1), the disclosures of which are hereby incorporated by reference in their entirety, together with the copies provided in the appendix.

[0028] Alternatively or in addition, the device 20 can use other methods of position detection to find the position of the electrode 48. For example, the processor 41 can map the position of the electrode 48 by measuring the impedance between the electrode 48 and the body surface electrode 49, which is placed on the patient 28's chest and connected to the console 24 by the lead 39.

[0029] The processor 41 additionally receives electrophysiological signals via the electrical interface 44 and utilizes the information contained in these signals together with the coordinates provided by the magnetic sensors 50A and 50B to construct an electroanatomical map 31 of the cardiac chamber 26 in which the catheter 40 is disposed. During and / or after the procedure, the processor 41 can display the electroanatomical map 31 on the display screen 27 (described in further detail in FIG. 3).

[0030] Processor 41 is typically programmed in software to perform the functions described herein. The software may be downloaded to the computer in electronic form, for example, via a network, or alternatively or additionally, provided and / or stored on a non-transitory tangible medium such as magnetic memory, optical memory, or electronic memory. In particular, processor 41 runs a dedicated algorithm that enables the processor to execute the disclosed steps as described below.

[0031] The illustration shown in FIG. 1 is selected merely for the purpose of making the concepts easier to understand. For simplicity and clarity, FIG. 1 shows only elements related to the disclosed techniques. Medical device 20 typically includes additional modules and elements not directly related to the disclosed techniques, and are thus intentionally omitted from FIG. 1 and the corresponding description. The elements of medical device 20 and the methods described herein may be further applied, for example, to control ablation of tissue in heart 26.

[0032] Measurement and Display of EP Parameters FIG. 2 is a flowchart 200 schematically illustrating an automated process for EP mapping according to an embodiment of the present invention. In this method, EP parameters from site 46 are incorporated into the map only when certain consistency criteria are met. The embodiment shown in flowchart 200 refers to an example of acquiring an EP signal from heart chamber 26 (see FIG. 1). In alternative embodiments, the values of the EP parameters will be apparent to those skilled in the art after a cursory reading of this description, but may be acquired from other organs and tissues as well as from the heart, using other types of mapping devices.

[0033] The process illustrated by flowchart 200 begins at start step 202. In map generation step 204, a uniform gray (or other suitable background color) 3D map of the heart cavity is generated by processor 41 and displayed 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 obtained by a catheter. Alternatively, the 3D map may be generated simultaneously with the display of the EP parameters. In catheter placement step 206, physician 30 places catheter 40 within heart 26 such that a group of electrodes 48 contacts myocardial tissue within site 46 of the heart cavity. In acquisition step 208, processor 41 receives signals from a group of electrodes 48 over a single time interval (such as a single heartbeat). In tracking step 209, processor 41 receives a signal from tracking module 43 and calculates the individual position coordinates of electrodes 48. In extraction step 210, processor 41 extracts a set of EP parameters from the signals received in acquisition step 208.

[0034] In consistency calculation step 212, processor 41 calculates a measure of consistency for the set of EP parameters extracted in extraction step 210. The measure of consistency, and the consistency criteria, are defined in this embodiment with respect to the variation between peaks of the EP parameters over a given set. For example, if the EP parameter calculated in step 210 is the local activation time (LAT), the consistency criteria may be adopted as a range of ±10 ms, that is, if the LATs within the set are within 20 ms of each other, they are considered to meet the consistency criteria. In another example, if the EP parameter is the bipolar or unipolar maximum voltage in the signal detected by electrodes 48, the consistency criteria may be adopted as a range of 20 mV, such that the maximum voltage measured within this range is considered to meet the consistency criteria. Alternatively, a larger or smaller range of the parameter may be adopted as the consistency criteria.

[0035] Alternatively, other types of consistency criteria may be applied. For example, the processor 41 can calculate the average value of the EP parameters in question and the variance value of the parameters over a series of heartbeats, and define a consistency criterion regarding the maximum acceptable variance value.

[0036] In the first determination step 214, the processor 41 compares the consistency measure calculated in step 212 with a predetermined consistency criterion. If the consistency measure meets the consistency criterion, the processor 41 includes the set of EP parameters within the approved set in the inclusion step 216. If the consistency measure does not meet the criterion, the processor 41 discards the set of EP parameters in the discard step 218.

[0037] From both the inclusion step 216 and the discard step 218, the process proceeds to a second determination step 220, where the processor 41 determines whether more sets of EP parameters are to be obtained from the current site 46 based on a preset criterion. For example, if the consistency measure did not meet any of the consistency criteria for the sets of EP parameters obtained from the current site 46, additional acquisitions may be required. Alternatively or in addition, further acquisitions may be desirable for averaging over a number of approved sets. If more acquisitions are required, the process returns to step 208.

[0038] If more acquisitions are not required, the set of EP parameters collected in step 216 may optionally be averaged in averaging step 222. Alternatively, averaging step 222 may be bypassed and only one of the approved sets of EP parameters may be selected for output. The resulting (averaged or non-averaged) representation of the EP parameters is overlaid on the 3D map in display step 224. In display step 224, processor 41 displays the EP parameters, for example, by applying corresponding color codes to the appropriate region of the 3D map generated in step 204 based on the position coordinates received in tracking step 209. The color coding can include, for example, showing the lowest value of the EP parameters as blue, the highest value as red, and the intermediate values between the lowest and highest values in the same order as colors in the visible spectrum. However, other color coding schemes, and other types of shading or symbols, such as those known in the art, may be used instead.

[0039] After display step 224, the process proceeds to a third decision step 226 where physician 30 determines whether additional sites are to be included in the mapping. If the determination is affirmative, physician 30 moves catheter 40 to the new site 46 in step 206 and the process continues as described above from there. When physician 30 determines that the mapping is complete, the process ends at end step 228.

[0040] FIG. 3 is a schematic diagram of an electroanatomical map 31 according to an embodiment of the present invention. After step 204 (FIG. 2), the 3D map 300 is initially colored achromatically, such as gray, on display screen 27. If the EP parameters acquired by basket catheter 40 meet the applicable consistency criteria, the colored overlay 302 is overlaid on 3D map 300 according to the method of FIG. 2.

[0041] The above-described embodiments relate to the measurement of EP parameters of the heart 26. In alternative embodiments, the methods described for the automatic approval or rejection of EP parameters may be applied to other tissues of the patient 28's body. Further, in alternative embodiments, more than one type of EP parameter may be measured and displayed simultaneously.

[0042] Accordingly, the embodiments described above are cited by way of example, and it will be understood that the present invention is not limited to those specifically illustrated and described above. Rather, the scope of the present invention includes both the various combinations and sub-combinations of the features described in the above specification, as well as those variations and modifications thereof that would occur to one of ordinary skill in the art upon reading the foregoing description and that are not disclosed in the prior art.

[0043] [Embodiments] (1) A medical device, a probe configured to be inserted into a patient's body and including a plurality of electrodes configured to contact tissue within the body at a series of time intervals, a display screen, a position tracking system configured to acquire position coordinates of the electrodes within the body, and a processor, wherein the processor is configured to acquire individual electrophysiological signals from a group of the electrodes at each of the series of time intervals while the electrodes are in contact with a site of the tissue and at individual positions within the site, extract individual electrophysiological parameters from the individual electrophysiological signals acquired at each time interval by the electrodes within the group, calculate individual coherence measures from among the individual electrophysiological parameters extracted from the electrophysiological signals acquired by the electrodes within the group during each time interval at each time interval, While visually displaying the extracted electrophysiological parameters at the individual positions of the electrodes within the time interval, where the individual coherence measures meet a predetermined coherence criterion, overlaying the display on a three-dimensional (3D) map of the tissue in response to the position coordinates, and automatically discarding from the map the electrophysiological parameters extracted during the time interval where the individual coherence measures do not meet the predetermined coherence criterion, a medical device configured to perform the above. (2) The medical device according to embodiment 1, wherein the electrophysiological parameter includes a local activation time (LAT) in the patient's heart, and the coherence measure indicates a variation in the LAT. (3) The medical device according to embodiment 2, wherein the coherence measure includes a peak-to-peak variation of the LAT in any given time interval, and the coherence criterion requires that the peak-to-peak variation of the LAT does not exceed a predetermined limit value. (4) The medical device according to embodiment 1, wherein the electrophysiological parameter includes an electrophysiological voltage, and the coherence measure indicates a variation in the electrophysiological voltage. (5) The medical device according to embodiment 4, wherein the coherence measure includes a peak-to-peak variation of the electrophysiological voltage in any given time interval, and the coherence criterion requires that the peak-to-peak variation of the electrophysiological voltage does not exceed a predetermined limit value.

[0044] (6) The medical device according to embodiment 1, wherein the 3D map is displayed in a background color, and the visual display includes another color overlaid on the background color at the individual positions to indicate the value of the extracted electrophysiological parameter. (7) A method for electrophysiological mapping, the method comprising: acquiring individual electrophysiological signals from a group of electrodes on a probe during a series of time intervals while the electrodes are in contact with a site of tissue within a patient's body; acquiring the position coordinates of the group of electrodes; extracting individual electrophysiological parameters from the individual electrophysiological signals acquired for each of the series of time intervals by the electrodes within the group; calculating individual coherence measures from among the individual electrophysiological parameters extracted from the electrophysiological signals acquired by the electrodes within the group during the time interval, for each time interval; displaying the map while superimposing a visual representation of the extracted electrophysiological parameters at the individual positions within the time interval, where the individual coherence measures meet a predetermined coherence criterion, onto the three-dimensional (3D) map of the tissue in response to the position coordinates, and automatically discarding from the map the electrophysiological parameters extracted during the time interval where the individual coherence measures do not meet the predetermined coherence criterion, the method comprising. (8) The method according to embodiment 7, wherein extracting the electrophysiological parameters includes extracting a local activation time (LAT) in the heart of the patient, and calculating the coherence measure includes calculating a measure indicative of variation of the LAT. (9) The method according to embodiment 8, wherein calculating the measure includes calculating the peak-to-peak variation of the LAT at any given time interval, and the coherence criterion requires that the peak-to-peak variation of the LAT during that time interval does not exceed a predetermined limit value. (10) The method according to embodiment 7, wherein extracting the electrophysiological parameters includes extracting an electrophysiological voltage in the heart of the patient, and calculating the individual coherence measure includes calculating a measure indicative of variation of the electrophysiological voltage.

[0045] (11) The method according to embodiment 10, wherein calculating the measure includes calculating the peak-to-peak variation of the electrophysiological voltage at any given time interval, and the coherence criterion requires that the peak-to-peak variation of the electrophysiological voltage during that time interval does not exceed a predetermined limit value. (12) Displaying the 3D map includes displaying the 3D map in a background color, and superimposing the visual display includes superimposing another color over the background color at the respective positions to indicate the respective values of the extracted electrophysiological parameters, the method according to embodiment 7.

Claims

1. A medical device, comprising a probe configured to be inserted into a patient's body and including a plurality of electrodes configured to contact tissue within the body at a series of time intervals, a display screen, a position tracking system configured to acquire position coordinates of the electrodes within the body, and a processor, wherein the processor is configured to acquire individual electrophysiological signals from the group of electrodes at each of the series of time intervals while the electrodes are in contact with a site of the tissue and at individual positions within the site, extract individual electrophysiological parameters from the individual electrophysiological signals acquired at each time interval by the electrodes within the group, calculate individual coherence measures from among the individual electrophysiological parameters extracted from the electrophysiological signals acquired by the electrodes within the group during each time interval, automatically discard the electrophysiological parameters extracted during the time interval if the individual coherence measures do not meet a predetermined coherence criterion, and display the 3D map on the display screen while superimposing a visual representation of the electrophysiological parameters extracted at the individual positions of the electrodes within the time interval, where the individual coherence measures meet the predetermined coherence criterion, onto a three-dimensional (3D) map of the tissue in response to the position coordinates. A medical device configured to perform the above.

2. The medical device according to claim 1, wherein the electrophysiological parameter includes a local activation time (LAT) in the patient's heart, and the coherence measure indicates a variation in the LAT.

3. The medical device according to claim 2, wherein the consistency measure includes the variation between peaks of the LAT at any given time interval, and the consistency criterion requires that the variation between peaks of the LAT does not exceed a predetermined limit value.

4. The medical device according to claim 1, wherein the electrophysiological parameter includes an electrophysiological voltage, and the consistency measure indicates the variation of the electrophysiological voltage.

5. The medical device according to claim 4, wherein the consistency measure includes the variation between peaks of the electrophysiological voltage at any given time interval, and the consistency criterion requires that the variation between peaks of the electrophysiological voltage does not exceed a predetermined limit value.

6. The medical device according to claim 1, wherein the 3D map is displayed in a background color, and the visual display includes other colors superimposed on the background color at the individual positions so as to indicate the values of the extracted electrophysiological parameters.

7. A method of operating a system for electrophysiological mapping, comprising: acquiring individual electrophysiological signals from a group of electrodes on a probe at a series of time intervals; acquiring the position coordinates of the group of electrodes; extracting individual electrophysiological parameters from the individual electrophysiological signals acquired for each of the series of time intervals by the electrodes within the group; calculating individual consistency measures from among the individual electrophysiological parameters extracted from the electrophysiological signals acquired by the electrodes within the group during the time interval, for each time interval; automatically discarding the electrophysiological parameters extracted during the time interval if the individual consistency measures do not meet a predetermined consistency criterion; The method of operating the system includes visually displaying the extracted electrophysiological parameters at the individual positions within the time interval where the individual consistency measures meet the predetermined consistency criteria, while superimposing the visual display on a three-dimensional (3D) map of tissue within the patient's body in response to the position coordinates, and displaying the 3D map. **Claim 8**: The system extracting the electrophysiological parameters includes the system extracting a local activation time (LAT), and the system calculating the consistency measure includes the system calculating a measure indicating the variation of the LAT. The method of operating the system according to claim 7. **Claim 9**: The system calculating the measure includes the system calculating the variation between peaks of the LAT at any given time interval, and the consistency criterion requires that the variation between peaks of the LAT during that time interval does not exceed a predetermined limit value. The method of operating the system according to claim 8. **Claim 10**: The system extracting the electrophysiological parameters includes the system extracting an electrophysiological voltage, and the system calculating the individual consistency measure includes the system calculating a measure indicating the variation of the electrophysiological voltage. The method of operating the system according to claim 7. **Claim 11**: The system calculating the measure includes the system calculating the variation between peaks of the electrophysiological voltage at any given time interval, and the consistency criterion requires that the variation between peaks of the electrophysiological voltage during that time interval does not exceed a predetermined limit value. The method of operating the system according to claim 10. **Claim 12**: The system displaying the 3D map includes the system displaying the 3D map in a background color, and the system superimposing the visual display includes the system superimposing another color on the background color at the individual positions to indicate the individual values of the extracted electrophysiological parameters. The method of operating the system according to claim 7.

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