Medical devices and programs

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 of a region within the body. The apparatus further includes a display screen, a position-tracking system, and a processor. The processor is configured to acquire electrophysiological signals from the electrodes, to extract electrophysiological parameters from the signals, to compute a measure of consistency of the electrophysiological parameters at each of the locations with respect to a weighted median of the parameters extracted at neighboring locations, and to render to the display screen a map of the tissue while overlaying on the map a visual indication of the extracted electrophysiological parameters for which the measure of consistency has satisfied a predefined consistency criterion, and automatically omitting from the map the electrophysiological parameters for which the measure of consistency has not satisfied the 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 technology]

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

[0003] For example, U.S. Patent No. 9,949,657, whose disclosure is incorporated herein by reference, describes a method for displaying electroanatomical information. The method comprises identifying at least one plurality of excited regions on the surface of the heart, wherein the plurality of excited regions recorded at least two distinct focal excitations during a single cardiac cycle of the heart. The plurality of excited regions are displayed on an electroanatomical map of the surface of the heart in a manner that indicates the time difference between the respective times of the two focal excitations. [Overview of the Initiative] [Means for solving the problem]

[0004] Embodiments of the present invention described herein hereafter provide improved methods and apparatus for mapping EP parameters.

[0005] According to embodiments of the present invention, a medical device is provided comprising a probe configured to be inserted into a patient's body, wherein the probe comprises one or more electrodes configured to contact tissue in a region within the body. The device further comprises a display screen, a position tracking system configured to acquire the position coordinates of one or more electrodes within the body, and a processor. The processor is configured to acquire electrophysiological signals from one or more electrodes while the one or more electrodes are in contact with multiple locations within the region, to extract each electrophysiological parameter from the electrophysiological signals, and to calculate each measure of consistency of each electrophysiological parameter at each location with respect to the weighted median of the electrophysiological parameters extracted at adjacent locations.

[0006] The processor is further configured to render a map of the organization on the display screen according to its location coordinates, overlay visual indicators of extracted electrophysiological parameters on the map for which each consistency measure meets the default consistency criteria, and automatically omit electrophysiological parameters from the map for which each consistency measure does not meet the default consistency criteria.

[0007] In the disclosed embodiments, for any given position, adjacent positions are selected such that the distance from the given position to each adjacent position is within a predetermined radius.

[0008] In another embodiment, the processor is configured to calculate each measure of consistency for any given location by calculating the difference between the electrophysiological parameters extracted at the given location and the weighted median of the electrophysiological parameters extracted at adjacent locations.

[0009] In further embodiments, the default consistency criterion is met if the calculated difference does not exceed a default threshold.

[0010] In the disclosed embodiments, the processor is configured to calculate a weighted median by applying a weight value to electrophysiological parameters extracted at adjacent positions using a weighting function selected from a list of weighting functions consisting of a distance weighting function, a reliability weighting function, and a variance weighting function.

[0011] In a further embodiment, for any given position, the distance weighting function applies a weight value that decreases by increasing the distance between the given position and the adjacent positions. Additionally or alternatively, the reliability weighting function is calculated for each given adjacent position according to the number of times an electrophysiological signal was acquired at the given adjacent position. Further additionally or alternatively, the variance weighting function applies a weight value that decreases by increasing the variance of the electrophysiological parameters projected onto the adjacent positions.

[0012] In the disclosed embodiments, the processor is configured to calculate a spatially continuous distribution of electrophysiological parameters in a region by interpolating only electrophysiological parameters extracted at positions where each measure of consistency meets a predefined consistency criterion, and render it on a display screen.

[0013] In yet another embodiment, the electrophysiological parameters include local activation arrival time (LAT) within the patient's heart. Additionally or alternatively, the electrophysiological parameters include electrophysiological voltage within the patient's tissue.

[0014] According to an embodiment of the present invention, a method of electrophysiological mapping is also provided. The method includes obtaining respective electrophysiological signals from one or more electrodes while the one or more electrodes are in contact with tissue at a plurality of positions in a region within a patient's body, obtaining position coordinates of the one or more electrodes at each of the positions within the body, and calculating respective measures of consistency of each of the electrophysiological parameters at each of the positions with respect to a weighted median of electrophysiological parameters extracted at adjacent positions. The method further includes rendering a map of the tissue on a display screen according to the position coordinates, overlaying on the map visual indicators of the extracted electrophysiological parameters for which the respective measures of consistency meet a predetermined consistency criterion, and automatically omitting from the map electrophysiological parameters for which the respective measures of consistency do not meet the predetermined consistency criterion.

Brief Description of the Drawings

[0015] The present invention will be more fully understood by considering the following "Modes for Carrying Out the Invention" in conjunction with the drawings. [Figure 1] FIG. 1 is a schematic depiction of a medical device for mapping EP parameters in a patient's heart according to an exemplary embodiment of the present invention. [Figure 2] FIG. 2 is a flowchart schematically illustrating an automated process for identifying and removing outliers from an EP map according to an exemplary embodiment of the present invention. [Figure 3] FIG. 3 is a flowchart schematically illustrating an automated process for identifying and removing outliers from an EP map according to an exemplary embodiment of the present invention. [Figure 4A] FIG. 4 is a schematic diagram of an EP map showing two stages of an outlier removal process according to an exemplary embodiment of the present invention. [Figure 4B] FIG. 5 is a schematic diagram of an EP map showing two stages of an outlier removal process according to an exemplary embodiment of the present invention.

Modes for Carrying Out the Invention

[0016] Overview To generate an electrophysiological (EP) map (electroanatomical mapping) of a patient's tissue, the physician positions the probe so that one or more electrodes on the probe are in contact with a region of tissue. The probe acquires an EP signal from one region and then repeats the process on other regions. From each location within the region where a signal is acquired, the processor analyzes the signal to extract the EP parameters of that location, such as the time to arrival (LAT) of local excitation within the cardiac chamber, or the EP voltage within the tissue. The EP parameter values ​​are then superimposed on a visual three-dimensional (3D) map of the region, for example as a color code, to form an EP parameter map that can be viewed by the physician. The mapping may be performed in real time.

[0017] At some locations within a region, the extracted values ​​of EP parameters may not match those at adjacent locations. These values ​​are called "outliers" or "outlying values." Such outliers may result, for example, from noisy EP signals at specific locations within the region. Outliers can distort the EP parameter map, and therefore, the information provided to physicians regarding the distribution of EP parameters across the region may be inaccurate. Even if EP signal acquisition is repeated, the visual map may still be distorted if there is no function to remove these problematic EP parameter values.

[0018] Embodiments of the present invention described herein address these problems by providing medical devices, methods, and software for automatically detecting and omitting outliers from an EP map. Specifically, EP parameters at a given location that do not meet consistency criteria when compared to the median of EP parameters at adjacent locations are omitted from the map.

[0019] In the disclosed embodiments, the apparatus comprises a probe, a display screen, a position tracking system, and a processor. A probe, having one or more electrodes, is inserted into the patient's body so that the electrodes contact the tissue of a region within the body, for example, a cardiac chamber. The position tracking system obtains the position coordinates of the electrodes within the body. The processor obtains EP signals from the electrodes while the electrodes are in contact with multiple locations within the region and extracts EP parameters from the signals. The processor calculates a consistency measure of the EP parameters extracted at each location with respect to the weighted median of the EP parameters extracted at adjacent locations. The processor renders a 3D map of the tissue on the display screen using an overlaid visual representation of the extracted EP parameters according to the position coordinates of those locations for which the consistency measure meets a predetermined consistency criterion, while automatically omitting EP parameters for which the respective consistency measure does not meet the consistency criterion.

[0020] For the purpose of calculating a measure of consistency at a selected location, adjacent locations may be defined, for example, as locations within a default radius of the selected location. In some embodiments, the processor calculates the measure of consistency as the difference between the EP parameter extracted at the selected location and the weighted median of the EP parameters extracted at adjacent locations. Alternatively, other measures of consistency, such as a normalized difference to the weighted median, may be used. If the measure of consistency does not exceed a default threshold, the EP parameter extracted at the selected location is considered to meet the consistency criteria, i.e., is not an outlier.

[0021] Typically, the processor calculates the weighted median using one or a combination of the following weighting functions (distance weighting function, reliability weighting function, and variance weighting function), but alternatively, other weighting functions may be used. Alternatively, the weights may be pre-set to specific preferred values, including applying equal weights to all adjacent positions involved in the weighted median.

[0022] For the purpose of rendering an EP map, the processor typically computes a spatially continuous distribution of EP parameters within a region by interpolating EP parameters extracted at locations where the consistency measure satisfies a predetermined consistency criterion (i.e., where the EP parameter is not an outlier). This spatially continuous distribution is superimposed onto the 3D map, effectively replacing outliers in the map with interpolated values, thereby avoiding errors in the map that would otherwise occur.

[0023] System Description Figure 1 is a schematic diagram 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. The embodiments shown in the present and subsequent figures refer to examples of acquiring EP signals from the cardiac chambers 26. In alternative embodiments, the values ​​of EP parameters may be acquired not only from the heart but also from other organs and tissues using other types of mapping devices, as will be obvious to those skilled in the art after reading this description.

[0024] The physician 30 guides the catheter 40 to a target position (inset 25) within the patient's heart 28 by manipulating the shaft 22 using deflection from the manipulator 32 and / or sheath 23 near the proximal end of the catheter. In the illustrated embodiment, the catheter 40 has a basket assembly at its distal end, as shown inset 45, but other types of catheters may be used, as is well known in the art. In the embodiment shown inset 25, the physician 30 uses the catheter 40 to perform electroanatomical mapping of the cardiac chambers 26. EP signals are acquired from the tissue by bringing electrodes 48 on the catheter 40 into contact with the tissue within the heart, as will be further detailed below.

[0025] The catheter 40 is inserted in a folded configuration via the sheath 23, as shown in insert diagram 45, and only after the catheter exits the sheath 23 does it expand to its intended functional shape. The sheath 23 also serves to minimize vascular trauma on its way to the target location by constraining the catheter 40 in its folded configuration.

[0026] For position tracking purposes, the catheter 40 incorporates a magnetic sensor 50A, as shown in inset 45, at the distal end of the shaft 22 (i.e., the proximal end of the basket-type assembly). While not typically required, sensor 50A is a triple-axis sensor (TAS) comprising three small coils oriented in different directions. In the illustrated embodiment, a second magnetic sensor 50B is incorporated at the distal end of the basket-type assembly. Sensor 50B may be, for example, a single-axis sensor (SAS) or a triple-axis sensor (TAS). Alternatively, the catheter 40 may be equipped with other types of magnetic sensors at these or other locations. Alternatively or additionally, the catheter may be equipped with other types of position sensors, such as impedance-based position sensors or ultrasonic position sensors, as are well known in the art.

[0027] The basket-shaped assembly at the distal end of the catheter 40 comprises multiple mechanically flexible, expandable dorsal columns 55. Multiple electrodes 48 are fixed to each dorsal column, for example, a total of 120 electrodes. The electrodes 48 are configured to contact the tissue of the patient 28 in order to detect EP signals. The magnetic sensors 50A and 50B and the electrodes 48 are connected to various processing circuits in the console 24 by wires (not shown) laid along the shaft 22.

[0028] Alternatively, the device 20 may include other types of catheters, such as an expandable balloon catheter with electrodes 48 on its outer surface, or a catheter having one or more flexible arms at its distal end, or other types of electrode arrays.

[0029] The medical device 20 includes a magnetic position tracking subsystem 43 of the console 24 for determining the position and orientation of the distal end of the catheter 40 and, consequently, 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 the position tracking subsystem 43. The magnetic field generated by the coil 42 produces electrical signals at sensors 50A and 50B, which indicate the position and orientation of the sensors. The signals from sensors 50A and 50B are transmitted back to the position tracking subsystem 43, which converts these signals into corresponding digital input values ​​for the processor 41. The processor 41 uses these input values ​​to calculate the position and orientation of the distal end of the catheter 40 and, therefore, find the respective positions of the electrodes 48.

[0030] Methods for detecting position and / or orientation using an external magnetic field and magnetic sensors such as sensors 50A and 50B are used 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. Patents 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 Publications 2002 / 0065455(A1), 2003 / 0120150(A1) and 2004 / 0068178(A1), all of which are incorporated herein by reference.

[0031] Alternatively or additionally, as described above, the device 20 may determine the position of the electrode 48 using other methods of position detection. For example, the processor 41 may map the position of the electrode 48 by measuring the impedance between the electrode 48, which is placed on the chest of the patient 28 and connected to the console 24 by leads 39, and the electrode 49 on the body surface.

[0032] The processor 41 receives additional EP signals from electrodes 48 on the catheter 40 via the electrical interface 44, and utilizes 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 cardiac chamber 26 in which the catheter 40 is located. During and / or after the procedure, the processor 41 may render the electroanatomical map 31 on the display screen 27.

[0033] The processor 41 is typically programmed to perform the functions described herein in software. The software can be downloaded electronically to a computer, for example, over a network, or alternatively or additionally, it can be provided and / or stored on a non-temporary physical medium such as magnetic memory, optical memory, or electronic memory. In particular, the processor 41 operates a dedicated algorithm that enables the processor to perform the disclosed steps as described below.

[0034] The examples shown in Figure 1 are selected solely for the purpose of illustrating the concepts. For simplicity and clarity, Figure 1 shows only the elements relevant to the disclosed technology. The medical device 20 typically includes additional modules and elements not directly related to the disclosed technology, which are intentionally omitted from Figure 1 and the corresponding description. The elements of the medical device 20 and the methods described herein may be further applied, for example, to control the ablation of cardiac tissue 26.

[0035] Outlier detection and display of EP parameters Figures 2 and 3 are flowcharts 200 and 300, respectively, illustrating an automated process for identifying and removing outliers from an EP map according to a representative embodiment of the present invention. Flowchart 200 shows the overall process for acquiring and extracting EP parameters and identifying and removing outliers from an EP parameter map, while flowchart 300 shows the calculation of the consistency measure used when identifying outliers. For specificity and clarity, this process is described below with respect to the elements of the apparatus 20 (Figure 1). Alternatively, the principle of this method may be applied with modifications to other system configurations, including a configuration in which EP signals are processed by a remote server and communicate with a mapping device over a network.

[0036] Referring to Figure 2, the process of acquiring and extracting EP parameters and identifying and removing outliers from the EP parameter map begins in step 202. In step 203, the parameters used in the consistency measurement step 214 and the determination step 216 are set. These parameters are described in detail below in Figure 3.

[0037] In acquisition step 204, the EP signal is acquired by the processor 41 via the electrodes 48 of the catheter 40 from the heart 26, referring to Figure 1.

[0038] In the tracking process 206, the processor 41 receives signals from the tracking module 43 and calculates the position coordinates of each electrode 48.

[0039] In extraction step 208, the processor 41 extracts the respective EP parameters from the acquired signals. For example, the processor 41 may calculate the local excitation time to arrival (LAT) at each location by finding the time (relative to a reference time) at which the signal measured at the location exhibits a peak or the highest slope. Alternatively or additionally, the processor 41 may calculate the peak amplitude of the signal and / or any other signal parameters of the subject at each location.

[0040] In the position assignment step 210, the processor 41 assigns the EP parameters (separate EP parameters) extracted at a given position within the heart to the corresponding positions on a 3D map of the cardiac chambers 26 based on the position coordinates received in the tracking step 206. The 3D map is generated, for example, from images of the heart previously stored in the processor and / or from position measurements acquired in the tracking step 206.

[0041] Sometimes, one (or more) of the electrodes 48 may not be in contact with the surface of the heart 26 while acquiring the EP signal. In this case, the position coordinates of the particular electrode 48 received in the tracking step 206 do not coincide with the surface of the heart 26, and the mapped position is “separated” from the surface. For brevity, the term “mapped position” in the following description refers to the position within the heart from which the EP parameters are extracted. To assign such a mapped position to a 3D map of the heart 26, the position within the heart is projected onto the nearest position on the surface of the heart, and this position within the heart is assigned a mapped position and displayed on the EP parameter map. When the catheter 40 with multiple electrodes 48 moves across the surface of the tissue of the heart 26, possibly several times, multiple “separated” mapped positions may be projected onto the same position on the surface. In such cases, the median of the EP parameters projected onto the same position is used for that position.

[0042] In the selection step 212, the processor 41 selects mapped locations to determine whether the EP parameter extracted at that location is an outlier, i.e., whether the consistency measure satisfies the consistency criterion. The mapped locations are selected from those locations, including projected locations that have not yet been processed in the consistency measurement step 214. In step 214, the processor 41 calculates the consistency measure for the EP parameter extracted at the mapped locations selected in the selection step 212. For example, the consistency measure may be proportional to the difference between the EP parameter at a given location and the weighted median of each EP parameter in a set of adjacent locations, as detailed in Figure 3. In this case, a large consistency measure indicates that the EP parameter at a given location does not match its adjacent system, and vice versa. Alternatively, the consistency measure may be defined such that a large value indicates that the EP parameter at a given location matches its adjacent system, and a small value indicates that the EP parameter is not consistent.

[0043] In the decision step 216, the processor 41 evaluates the consistency measure from step 214 against a predetermined consistency criterion. For example, the consistency measure may be compared against a threshold defined in the parameter setting step 203. Assuming the consistency measure is defined to increase with the difference between a given location and its neighboring systems, if the consistency measure exceeds the threshold, the EP parameter extracted at the selected location does not satisfy the consistency criterion. In this case, the EP parameter is considered an outlier, and the automated process is directed to the outlier marking step 218. In the decision step 216, the difference between the consistency measure and the threshold is used as the consistency criterion, but as mentioned earlier, other criteria may be used instead.

[0044] In the outlier marking step 218, the processor 41 marks the EP parameters extracted at the selected mapped locations as outliers, and the process proceeds to an additional positioning step 220. Marking may include, for example, the processor 41 adding an indicator flag to the list of mapped locations in its memory.

[0045] If the EP parameters extracted at the selected mapped location are not considered outliers in the determination step 216, the automated process proceeds directly to an additional positioning step 220.

[0046] In the additional positioning step 220, the processor 41 determines whether there are still positions between mapped positions that have not been processed through the consistency measurement step 214. If so, the process returns to the selection step 212. If there are no more such positions, the process proceeds to the continuous display correction step 222.

[0047] In the map generation step 222, the processor 41 generates an EP parameter map of the cardiac chambers 26. The 3D map of the cardiac chambers (from step 210) is overlaid with either or both of the EP parameters extracted at a given location and the interpolated map of the EP parameters, as further described below. At this stage of the process, all mapped locations are displayed, including those that may have out-of-range EP parameters. However, only non-outlier mapped locations are used in the interpolated map.

[0048] The processor 41 displays the EP parameters extracted at a given position (separate EP parameters) on the EP parameter map as small colored circles (or some other preferred shapes), for example, based on step 210. The coloring may include, for example, using blue for the lowest value of the EP parameter, red for the highest value, and in the same order, using a color in the visible spectrum for the intermediate values ​​between the lowest and highest values. However, other coloring schemes, such as those well known in the art, as well as shading or symbols, may be used instead.

[0049] Additionally or alternatively, the processor 41 computes and displays a spatially continuous map of EP parameters by interpolating non-outlier EP parameters extracted at a given position. The continuous map typically uses the same color coding as that used when displaying individual EP parameters.

[0050] The display of the EP parameter map on the display screen 27 may be controlled by the physician 30.

[0051] In the outlier removal step 224, outliers marked in the outlier marking step 218 (also referred to as "individual outliers") are removed from the EP parameter map, so that the map displays only the non-outlier EP parameters at their respective locations. As a result of steps 222 and 224, the modified EP parameter map of the cardiac chamber surface includes only the extracted non-outlier EP parameters and only the interpolated map calculated from these EP parameters. In other words, the processor 41 calculates a spatially continuous distribution of electrophysiological parameters within the cardiac chambers by interpolating only the electrophysiological parameters extracted at locations where each measure of consistency satisfies the consistency criteria. The display of the modified EP parameter map (without individual outliers) on the display screen 27 may again be controlled by the physician 30.

[0052] The automated process ends in termination step 226.

[0053] Referring here to Figure 3, flowchart 300 shows the details of calculating the consistency measure of EP parameters extracted at the selected mapped location. In flowchart 200 of Figure 2, this process is represented as consistency measurement step 214. When calculating the consistency measure of EP parameters extracted at the selected mapped location, the influence of EP parameters extracted at adjacent locations is considered both by defining the adjacent locations as detailed below in radius acquisition step 304, and by weighting their influences as detailed below in weighting function acquisition step 306 and predict EP parameter step 308.

[0054] The process begins in start step 302, where the mapped location selected from step 212 in Figure 2 is received. In radius acquisition step 304, the inclusion radius R is used to define adjacent locations. incl However, this is obtained from parameter step 203 in Figure 2. For example, a sphere has a mapped position selected as its center and R as its radius. incl It is defined as follows. All positions within this sphere are defined as "adjacent positions" and are included in determining whether a selected position is an outlier.

[0055] In the weighting function acquisition step 306, the processor 41 acquires the weighting function (described in further detail below) from step 203. In the weighted median calculation step 308, the processor 41 calculates the adjacent position (radius R) by applying an appropriate weight value to each of the EP parameter values, as shown by the weighting function. incl The weighted median of the EP parameters extracted (at the specified location) is calculated. The term “weighted median” is used herein and in the claims in its conventional sense in the statistical art. Specifically, the values ​​are processed in ascending order, and each weighted value {w1, w2, ..., w} is calculated. n Each adjacent position L has} i ,{x1(L1),x2(L2),...,x n (L n )} EP parameter x i Given a set of values, this allows us to:

[0056] [Number] becomes, and the weighted median is

[0057] [Number] a value x that satisfies k can become. When all the weighting values are equal, the weighted median is equal to the simple median of {x1(L1), x2(L2),..., x n (L n )}.

[0058] The processor 41 uses the weighted median in the consistency measurement step 310 to calculate a measure of consistency as the difference between the EP parameter extracted at the selected mapped position and the weighted median of the EP parameters extracted at adjacent positions. The process of flowchart 300 ends in an end step 312 that passes the measure of consistency to step 216 of FIG. 2.

[0059] Weighting function Any suitable weighting function or combination of functions may be selected in the acquisition step 306. The embodiment shown in FIG. 3 includes a distance weighting function f dist , a reliability weighting function f conf , and a variance weighting function f var .

[0060] Using the distance weighting function f dist , the processor 41 calculates the weighting values to take into account the influence of the distance to adjacent positions from the selected position on the weighted median. In one embodiment, the weighting value of the EP parameter extracted at a given adjacent position i is f dist = (1 - r i / R incl ) / A dist defined as, where r i is the distance between position i and the selected position, and A dist is f distThe sum of the weighted values ​​defined by the formula is normalized to 1. Therefore, EP parameters extracted at adjacent positions close to the selected position have higher weighted values ​​than EP parameters extracted at positions further adjacent to the selected position.

[0061] Reliability weighting function f conf Using this, the processor 41 calculates a weighted value based on the reliability level of the EP parameters extracted at the adjacent position. The reliability level at the adjacent position is influenced, in particular, by the number of times the EP signal is acquired at a given position by repeated measurements by the electrode 48. In one embodiment, the reliability weighting function f for the EP parameters extracted at the adjacent position i conf is, f conf =n i Defined as / N, where n i n refers to the number of times the signal was sampled at position i, and n refers to the total number of sampled signals. Therefore, for example, an EP parameter extracted at an adjacent position from a signal sampled four times has four times the reliability level of an EP parameter extracted at another adjacent position from a signal sampled only once. Alternatively or additionally, other measures of reliability, such as positional stability, pressure, or impedance, measured during signal acquisition at each of the neighboring positions may be used.

[0062] Variance weighting function f var Using this, the processor 41 calculates weights based on the variance between multiple EP parameters extracted at adjacent locations, as shown in step 210 of Figure 2, when these locations are projected onto the same locations on the surface of the heart 26. The smaller the variance between these EP parameters, the greater the influence of these EP parameters on the calculation of the consistency measure. In one embodiment, the variance weighting function f at location i on the surface of the heart 26 var is, f var =1-(σ i 2 / A var ) is defined as, σ i 2 This refers to the variance of the EP parameter extracted at the position projected onto position i, and Avar This is the coefficient that normalizes the sum of the weighted values ​​to 1. Variance weighting function f var This could be further modified to take into account the number of mapped locations projected onto the same location. For example, two locations that exhibit the same variance but contribute a similar number of projected locations, but a location with more projected locations will have a higher weight in the calculation of the weighted median.

[0063] In alternative embodiments, other forms of the weighting function, whether continuous or distinct, may be used.

[0064] When setting the weighting function in the parameterization process 203 in Figure 2, one may choose the relative influence of three weighting functions: distance, reliability, and variance. For example, three weighting functions f dist ,f conf , and f var The compound weighted function f composite By appropriately combining them, only one of the weighting functions, or any combination of weighting functions, may be included in the calculation of outliers. In either case, the weighting functions are normalized so that the composite weight value across each set of adjacent positions is 1.

[0065] Render the map Figures 4A and 4B are schematic diagrams of EP parameter maps 402A and 402B, respectively, illustrating two stages of the outlier removal process according to a representative embodiment of the present invention. Both maps 402A and 402B are based on a 3D map 408 of the same region of the cardiac chamber 26 and accompanied by the same sequential map of EP parameter values, so as to be interpolated from non-outlier EP parameters. The difference between the two maps is that map 402A displays all distinct mapped locations, including outliers, whereas map 402B displays only the distinct mapped locations of non-outliers.

[0066] Figure 4A shows an EP parameter map 402A with multiple mapped locations 404 of an EP parameter, such as LAT, superimposed on a 3D map 408. The mapped locations 404 are represented as small circles with the values ​​of their respective EP parameters, indicated by color coding, as described in the map generation process 222 of Figure 2. Figure 4A also shows a region 406A on map 402A that displays a continuous map of EP parameter values, which are interpolated from non-outlier EP parameters extracted at the mapped locations 404. Region 406A is color-coded with the same sign as the EP parameters extracted at the mapped locations 404. Region 409 on map 402A is represented as a uniform neutral color, such as gray, and does not represent either the mapped locations 404 or region 406A (interpolated map), extending to this portion of the 3D map 408, meaning that this region does not display any arbitrary values ​​of the EP parameters.

[0067] The EP parameters extracted at mapped locations 410 and 412 are marked as outliers by an automated process (step 218 in Figure 2), but are left in Figure 4A if the physician 30 wishes to explore them further. These mapped locations can also be visually identified as outliers at this stage by their differences from the EP parameters extracted at their respective adjacent mapped locations. The EP parameters extracted at mapped location 414 are very similar to those at mapped location 412, but are not outliers because some of their immediate adjacent systems have the same values ​​as the EP parameter values. Map 402A corresponds to the stage immediately following step 222 of the map generation process in flowchart 200 in Figure 2, and its display on the display screen 27 may be controlled by the physician 30.

[0068] Figure 4B shows the same regions and locations as Figure 4A, except that outliers have been removed (at mapped locations 410 and 412). Region 406B, which displays the continuously interpolated EP parameters, is identical to region 406A in Figure 4A. Map 402B corresponds to a later stage in the flowchart 200, after the outlier removal process 224. As described above, its display on the display screen 27 may be controlled by the physician 30.

[0069] The embodiments described above are illustrative, and it will be understood that the present invention is not limited to those specifically illustrated and described herein. Rather, the scope of the present invention includes both combinations and partial combinations of the various features described above herein, as well as variations and modifications thereof not disclosed in the prior art, which will be conceived by those skilled in the art upon reading the foregoing description.

[0070] [Implementation Method] (1) A medical device, A probe comprising one or more electrodes configured to be inserted into a patient's body and to come into contact with the tissue of a region within the body, Display screen and, A position tracking system configured to acquire the position coordinates of one or more electrodes within the body, It is a processor, While one or more electrodes are in contact with multiple positions within the region, electrophysiological signals are acquired from each of the one or more electrodes. Each electrophysiological parameter is extracted from the aforementioned electrophysiological signals. With respect to the weighted median of the electrophysiological parameters extracted at adjacent locations, the respective measure of consistency of each electrophysiological parameter is calculated for each of the locations. A medical device comprising: a processor configured to render a map of the tissue on a display screen according to the position coordinates, overlay visual indicators of the extracted electrophysiological parameters on the map for which each of the consistency measures satisfies a predetermined consistency criterion, and automatically omit from the map any electrophysiological parameters for which each of the consistency measures did not satisfy the predetermined consistency criterion. (2) The medical device according to Embodiment 1, wherein, for any given position, the adjacent positions are selected such that the distance from the given position to each adjacent position is within a predetermined radius. (3) The medical device according to Embodiment 1, wherein the processor is configured to calculate each measure of consistency for any given location by calculating the difference between the electrophysiological parameter extracted at the given location and the weighted median of the electrophysiological parameter extracted at an adjacent location. (4) The medical device according to Embodiment 3, wherein the predetermined consistency criterion is satisfied when the calculated difference does not exceed a predetermined threshold. (5) The medical device according to Embodiment 1, wherein the processor is configured to calculate the weighted median by applying weighted values ​​to the electrophysiological parameters extracted at the adjacent positions using a weighting function selected from a list of weighting functions consisting of a distance weighting function, a reliability weighting function, and a variance weighting function.

[0071] (6) The medical device according to Embodiment 5, wherein for any given position, the distance weighting function is applied with a weight that decreases as the distance between the given position and the adjacent position increases. (7) The medical device according to Embodiment 5, wherein the reliability weighting function is calculated for each given adjacent position according to the number of times an electrophysiological signal has been acquired at the given adjacent position. (8) The medical device according to Embodiment 5, wherein the variance weighting function applies weights that decrease by increasing the variance of the electrophysiological parameters projected onto the adjacent positions. (9) The medical device according to Embodiment 1, wherein the processor is configured to compute a spatially continuous distribution of the electrophysiological parameters in the region and render it on the display screen by interpolating only the electrophysiological parameters extracted at the locations where each measure of consistency satisfies the predetermined consistency criterion. (10) The medical device according to Embodiment 1, wherein the electrophysiological parameters include the time to local excitation (LAT) in the patient's heart.

[0072] (11) The medical device according to Embodiment 1, wherein the electrophysiological parameters include an electrophysiological voltage within the patient's tissue. (12) A method for electrophysiological mapping, wherein the method is The process involves acquiring electrophysiological signals from one or more electrodes while they are in contact with tissue at multiple locations within a region of the patient's body, To obtain the position coordinates of one or more electrodes at each of the aforementioned locations within the body, At each of the aforementioned locations, the respective electrophysiological parameters are extracted from the electrophysiological signals, With respect to the weighted median of the electrophysiological parameters extracted at adjacent locations, the respective measures of consistency of each electrophysiological parameter are calculated for each of the locations, A method comprising rendering a map of the organization on the display screen according to the position coordinates, overlaying visual indicators of the extracted electrophysiological parameters on the map for which each of the consistency measures satisfies a predetermined consistency criterion, and automatically omitting from the map the electrophysiological parameters for which each of the consistency measures did not satisfy the predetermined consistency criterion. (13) The method of Embodiment 12, wherein calculating each of the measures includes selecting the adjacent positions such that, for any given position, the respective distance from the given position to the adjacent position is within a predetermined radius. (14) The method of Embodiment 12, wherein calculating each measure of consistency includes, for any given position, calculating the difference between the electrophysiological parameter extracted at the given position and the weighted median of the electrophysiological parameter extracted at an adjacent position. (15) The method according to Embodiment 14, wherein the default consistency criterion is satisfied if the calculated difference does not exceed a default threshold.

[0073] (16) The method of Embodiment 12, wherein calculating each measure of consistency includes calculating the weighted median by applying weighted values ​​to the electrophysiological parameters extracted at the adjacent positions using a weighting function selected from a list of weighting functions consisting of a distance weighting function, a reliability weighting function, and a variance weighting function. (17) The method of embodiment 16, wherein for any given position, the distance weighting function is applied with a weight that decreases as the distance between the given position and the adjacent position increases. (18) The method according to Embodiment 16, wherein the reliability weighting function is calculated for each given adjacent position according to the number of times an electrophysiological signal has been acquired at the given adjacent position. (19) The method according to embodiment 16, wherein the variance weighting function applies weights that decrease by increasing the variance of the electrophysiological parameters projected onto the adjacent positions. (20) The method of Embodiment 12, wherein rendering the map involves interpolating only the electrophysiological parameters extracted at the locations where each measure of consistency satisfies the predetermined consistency criterion, thereby calculating a spatially continuous distribution of the electrophysiological parameters in the region and rendering it on the display screen.

[0074] (21) The method according to Embodiment 12, wherein the electrophysiological parameters include the time to local excitation (LAT) in the patient's heart. (22) The method according to Embodiment 12, wherein the electrophysiological parameters include an electrophysiological voltage within the patient's tissue.

Claims

1. It is a medical device, A probe comprising one or more electrodes configured to be inserted into the patient's body and to come into contact with tissue in the region of the heart within the body, Display screen and, A position tracking system configured to acquire the position coordinates of one or more electrodes within the body, It is a processor, While one or more electrodes are in contact with multiple positions within the region, electrophysiological signals are acquired from each of the one or more electrodes. Each electrophysiological parameter is extracted from the aforementioned electrophysiological signals. With respect to the weighted median of the electrophysiological parameters extracted at adjacent locations, the respective measure of consistency of each of the electrophysiological parameters is calculated for each of the plurality of locations. The display screen is configured to render a map of the tissue according to the position coordinates of one or more electrodes, to overlay visual indicators of the electrophysiological parameters for which each consistency measure satisfies a predetermined consistency criterion onto the map, and to automatically omit from the map the electrophysiological parameters for which each consistency measure did not satisfy the predetermined consistency criterion. For any given position, the adjacent positions are selected such that the distance from the given position to each adjacent position is within a predetermined radius. The processor is configured to calculate each measure of consistency for any given location by calculating the difference between the electrophysiological parameter extracted at the given location and the weighted median of the electrophysiological parameter extracted at an adjacent location. The aforementioned default consistency criterion is satisfied if the calculated difference does not exceed a predetermined threshold. A medical device comprising: a processor configured to calculate the weighted median by applying weighted values ​​to the electrophysiological parameters extracted at the adjacent positions using a weighting function selected from a list of weighting functions consisting of a distance-weighted function, a reliability-weighted function, and a variance-weighted function.

2. The medical device according to claim 1, wherein for any given position, the distance weighting function is applied with a weight that decreases as the distance between the given position and the adjacent position increases.

3. The medical device according to claim 1, wherein the reliability weighting function is calculated for each given adjacent position according to the number of times an electrophysiological signal has been acquired at the given adjacent position.

4. The medical device according to claim 1, wherein the variance weighting function applies weights that decrease by increasing the variance of the electrophysiological parameters projected onto the adjacent positions.

5. The medical device according to claim 1, wherein the processor is configured to compute a spatially continuous distribution of the electrophysiological parameters in the region and render it on the display screen by interpolating only the electrophysiological parameters extracted at the plurality of locations where each measure of consistency satisfies the predetermined consistency criterion.

6. The medical device according to claim 1, wherein the electrophysiological parameters include the time to local excitation (LAT) in the patient's heart.

7. The medical device according to claim 1, wherein the electrophysiological parameters include electrophysiological voltages within the patient's tissue.

8. A program for electrophysiological mapping, wherein when the program is loaded into the processor of a medical device, the processor: The process involves acquiring electrophysiological signals from one or more electrodes while they are in contact with tissue at multiple locations in the cardiac region of the patient's body, To obtain the position coordinates of one or more electrodes at each of the multiple locations within the body, At each of the aforementioned multiple locations, the respective electrophysiological parameters are extracted from the electrophysiological signals. With respect to the weighted median of the electrophysiological parameters extracted at adjacent locations, the respective measures of consistency of each of the electrophysiological parameters are calculated for each of the multiple locations, The medical device's display screen renders a map of the tissue according to the position coordinates of one or more electrodes, overlays visual indicators of the electrophysiological parameters whose respective consistency measures meet a predetermined consistency criterion onto the map, and automatically omits the electrophysiological parameters whose respective consistency measures do not meet the predetermined consistency criterion from the map. Calculating each of the aforementioned scales includes selecting the adjacent positions such that, for any given position, the distance from the given position to each adjacent position is within a predetermined radius. Calculating each of the aforementioned consistency measures involves, for any given position, calculating the difference between the electrophysiological parameter extracted at the given position and the weighted median of the electrophysiological parameter extracted at adjacent positions. The aforementioned default consistency criterion is met if the calculated difference does not exceed a default threshold. A program for calculating each measure of consistency, wherein the processor calculates the weighted median by applying weighted values ​​to the electrophysiological parameters extracted at adjacent locations within a predetermined radius from the arbitrary given location, using a weighting function selected from a list of weighting functions consisting of distance-weighted functions, reliability-weighted functions, and variance-weighted functions.

9. The program according to claim 8, wherein for any given position, the distance weighting function applies a weight that decreases as the distance between the given position and the adjacent position increases.

10. The program according to claim 8, wherein the reliability weighting function is calculated for each given adjacent position according to the number of times an electrophysiological signal has been acquired at the given adjacent position.

11. The program according to claim 8, wherein the variance weighting function applies weights that decrease by increasing the variance of the electrophysiological parameters projected onto the adjacent positions.

12. The program according to claim 8, wherein rendering the map includes calculating a spatially continuous distribution of the electrophysiological parameters in the region and rendering it on the display screen by interpolating only the electrophysiological parameters extracted at the plurality of locations where each measure of consistency satisfies the predetermined consistency criterion.

13. The program according to claim 8, wherein the electrophysiological parameters include the time to local excitation (LAT) in the patient's heart.

14. The program according to claim 8, wherein the electrophysiological parameters include electrophysiological voltages within the patient's tissue.

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