Systems, methods and devices for mapping local activation time

Abstract

The electroanatomical mapping system graphically represents local activation time (LAT) information contained in a data set including a plurality of electrophysiological (EP) data points. The system calculates spatial gradients on a spatial kernel centered at the EP data point and a plurality of temporal gradients of the set of EP data points. Using the gradients, the electroanatomical mapping system can detect spatial outlier EP data points and temporal outlier EP data points. These outlier EP data points can then be corrected before outputting a graphical representation of a LAT map on a cardiac surface model.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of U.S. Provisional Application No. 62 / 990,267, filed on March 16, 2020, the entire contents of which are incorporated herein by reference as if fully set forth herein. Technical Field

[0003] The present disclosure relates generally to electrophysiological visualization and mapping. More specifically, the present disclosure relates to systems, methods, and devices for generating visualizations of local activation times. Background Art

[0004] Electrophysiological mapping, and more particularly electrocardiogram mapping, is part of many cardiac diagnostic and therapeutic procedures. However, as the complexity of such procedures increases, the electrophysiological maps used must improve in quality, density, and the speed and ease with which they can be generated.

[0005] Electrophysiological studies may include creating a local activation time (LAT) map. For example, a LAT map may provide a practitioner with insight into how an arrhythmia is progressing in a cardiac chamber. In practice, one of ordinary skill in the art will be familiar with the graphical representation of a LAT map in an electroanatomical mapping system.

[0006] However, existing electroanatomical mapping systems sometimes exhibit abnormal LAT spikes in their graphical representations of LAT maps. These spikes are referred to herein as "outliers."

[0007] There are multiple reasons for outliers. For example, for highly complex convex anatomical geometries such as the left atrial appendage or ventricular apex, stacking electrophysiological data points in the middle of a convex surface may result in incorrect projections onto the surface.

[0008] As another example, in cases where electrophysiological data points are very close to each other and thus clustered into replicate sets, incorrect LAT selection for the replicate sets may result in outliers.

[0009] As yet another example, complex electrograms with low amplitude, long, and graded potentials, such as may be encountered in low voltage myocardium, may make correct determination of LAT challenging and result in outlier values.

[0010] Outliers may also be caused by cardiac and / or respiratory motion or mechanical artifacts (eg, catheter splines touching each other during collection of some but not all electrophysiological data points). Summary of the invention

[0011] The present invention discloses a method for graphically representing local activation time (LAT), comprising the following steps: receiving, at an electroanatomical mapping system, a LAT data set comprising a plurality of electrophysiological (EP) data points, wherein each of the plurality of EP data points comprises positioning information and an electrogram signal; the electroanatomical mapping system calculating a spatial gradient on a spatial kernel, the spatial kernel being centered on the EP data point in the plurality of EP data points of the LAT data set; the electroanatomical mapping system calculating a corresponding temporal gradient for each of the plurality of EP data points in the LAT data set, thereby calculating a plurality of temporal gradients; the electroanatomical mapping system detecting spatial outlier EP data points within the spatial kernel using the spatial gradient; the electroanatomical mapping system detecting temporal outlier EP data points using the plurality of temporal gradients; the electroanatomical mapping system correcting the spatial outlier EP data points and the temporal outlier EP data points, thereby creating a corrected LAT map; and the electroanatomical mapping system outputting a graphical representation of the corrected LAT map on a heart surface model.

[0012] In an embodiment of the present disclosure, receiving a LAT data set including multiple electrophysiological (EP) data points at an electroanatomical mapping system may include: projecting each EP data point onto a heart surface model using positioning information of the corresponding EP data point; and assigning LAT to each projected EP data point using an electrogram signal of the corresponding EP data point.

[0013] According to aspects of the present disclosure, the electroanatomical mapping system may define a spatial kernel for each EP data point in a plurality of EP data points and calculate a spatial gradient for each defined spatial kernel. Alternatively, the electroanatomical mapping system may accept user input selecting a subset of the plurality of EP data points, define a spatial kernel for each EP data point in the subset of the plurality of EP data points, and calculate a spatial gradient for each defined spatial kernel. In further embodiments, the electroanatomical mapping system may identify a high LAT gradient region in a LAT dataset, define a spatial kernel for each EP data point in the high LAT gradient region, and calculate a spatial gradient for each defined spatial kernel.

[0014] It is expected that the electroanatomical mapping system will detect spatial outlier EP data points by comparing the spatial gradient to a spatial gradient threshold. The spatial gradient threshold can be a user preset value or a calculated scaled mean absolute deviation value.

[0015] Similarly, the electroanatomical mapping system can detect temporal outlier EP data points by comparing multiple temporal gradients to a temporal gradient threshold value. The temporal gradient threshold value can be a user preset value or a calculated scaled mean absolute deviation value.

[0016] In an embodiment of the present disclosure, the electroanatomical mapping system corrects spatial outlier EP data points and temporal outlier EP data points to create a corrected LAT mapping map, including the electroanatomical mapping system applying at least one of a LAT value dispersion algorithm and a peak frequency dispersion algorithm to the spatial outlier EP data points and the temporal outlier EP data points.

[0017] Optionally, the method may include the electroanatomical mapping system spatially smoothing the LAT dataset.For example, the electroanatomical mapping system may apply a Gaussian distribution to the spatial kernel.

[0018] The present invention also discloses a method for graphically representing local activation time (LAT), comprising the following steps: receiving a LAT map at an electroanatomical mapping system, the LAT map comprising a plurality of electrophysiological (EP) data points; the electroanatomical mapping system identifying at least one of a spatial outlier EP data point and a temporal outlier EP data point within the plurality of EP data points; the electroanatomical mapping system correcting at least one of the identified spatial outlier EP data point and the temporal outlier EP data point to create a corrected LAT map; and the electroanatomical mapping system outputting a graphical representation of the corrected LAT map on a cardiac surface model.

[0019] In aspects of the present disclosure, an electroanatomical mapping system identifies at least one of a spatial outlier EP data point and a temporal outlier EP data point within a plurality of EP data points by: calculating a spatial gradient on a spatial kernel centered at an EP data point among the plurality of EP data points; calculating a temporal gradient on a temporal kernel for an EP data point among the plurality of EP data points; and identifying at least one of a spatial outlier EP data point and a temporal outlier EP data point using the calculated spatial gradient and the calculated temporal gradient.

[0020] The electroanatomical mapping system can correct at least one of the identified spatial outlier EP data points and temporal outlier EP data points to create a corrected LAT map, including the electroanatomical mapping system applying at least one of a LAT value dispersion algorithm and a peak frequency dispersion algorithm to at least one of the spatial outlier EP data points and the temporal outlier EP data points.

[0021] The present disclosure also provides a system for graphically representing local activation time (LAT). The system includes a visualization module, which is configured to: receive a LAT data set including a plurality of electrophysiological (EP) data points, wherein each of the plurality of EP data points includes positioning information and an electrogram signal; calculate a spatial gradient on a spatial kernel centered at an EP data point in the plurality of EP data points of the LAT data set; calculate a corresponding temporal gradient for each of the plurality of EP data points in the LAT data set, thereby calculating a plurality of temporal gradients; detect spatial outlier EP data points within the spatial kernel using the spatial gradient; detect temporal outlier EP data points using the plurality of temporal gradients; correct the spatial outlier EP data points and the temporal outlier EP data points, thereby creating a corrected LAT map; and output a graphical representation of the corrected LAT map on a heart surface model.

[0022] The visualization module may be configured to identify high LAT gradient regions within the LAT data set and compute a plurality of spatial gradients over a corresponding plurality of spatial kernels, each of the plurality of spatial kernels being centered at a corresponding EP data point within the high LAT gradient region.

[0023] The visualization module may also be configured to correct the spatial outlier EP data points and the temporal outlier EP data points by applying at least one of a LAT value dispersion algorithm and a peak frequency dispersion algorithm to the spatial outlier EP data points and the temporal outlier EP data points.

[0024] The foregoing and other aspects, features, details, utilities and advantages of the present invention will become apparent from reading the following description and claims, and from reviewing the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 is a schematic diagram of an exemplary electroanatomical mapping system.

[0026] Figure 2 An exemplary catheter that may be used in conjunction with aspects of the present disclosure is depicted.

[0027] Figure 3A and 3B An alphanumeric labeling convention for electrodes carried by a multi-electrode catheter and their associated dipoles is provided.

[0028] Figure 4 is a flow chart of representative steps that may be performed in generating a graphical representation of local activation times according to an exemplary embodiment disclosed herein.

[0029] Figure 5 is an exemplary graphical representation of local activation time data prior to application of the techniques and teachings disclosed herein.

[0030] Fig. 6A and 6B A spatial kernel according to aspects of the present disclosure is depicted.

[0031] Figure 7 Windowed electrograms of abnormal EP data points are shown.

[0032] Figure 8 An electrogram showing the application of a peak frequency dispersion algorithm to outlier EP data points.

[0033] Fig. 9A and 9B A corrected LAT map is shown, which may be generated by applying the teachings herein.

[0034] Although multiple embodiments are disclosed, other embodiments of the present disclosure will become apparent to those skilled in the art from the following detailed description, which shows and describes illustrative embodiments. Therefore, the drawings and detailed description are to be regarded as illustrative in nature and not restrictive. DETAILED DESCRIPTION

[0035] The present disclosure provides systems, methods, and apparatus for visualizing electrophysiological maps (e.g., electrocardiograms). For purposes of illustration, several exemplary embodiments will be described in detail herein with reference to cardiac electrophysiology procedures. More specifically, aspects of the present disclosure will be described in the context of visualization of local activation time (LAT) maps using a high density (HD) mesh catheter (such as the Advisor from Abbott Laboratories (Abbott Park, IL)). TM HD grid mapping catheter) combined with an electroanatomical mapping system (such as the EnSite Precision TM However, one of ordinary skill in the art will appreciate how to apply the teachings herein to other environments and / or to advantage with respect to other devices.

[0036] Figure 1 A schematic diagram of an exemplary electroanatomical mapping system 8 is shown for conducting cardiac electrophysiological studies by navigating a cardiac catheter and measuring electrical activity occurring in a heart 10 of a patient 11 and three-dimensionally mapping the electrical activity and / or information related to or representative of the electrical activity so measured. For example, the system 8 can be used to create an anatomical model of the patient's heart 10 using one or more electrodes. The system 8 can also be used to measure electrophysiological data at multiple points along the surface of the heart and store the measured data in association with positional information for each measurement point at which the electrophysiological data was measured, for example to create a diagnostic data map of the patient's heart 10.

[0037] As will be appreciated by those of ordinary skill in the art, system 8 determines the position and in some aspects the orientation of objects, typically within three-dimensional space, and expresses those positions as position information determined relative to at least one reference. This is referred to herein as "positioning."

[0038] To simplify the illustration, the patient 11 is schematically depicted as an ellipse. Figure 1 In the embodiment shown in , three sets of surface electrodes (e.g., patch electrodes) are shown applied to the surface of patient 11, defining three generally orthogonal axes, referred to herein as the x-axis, y-axis, and z-axis. In other embodiments, the electrodes may be positioned in other arrangements (e.g., multiple electrodes on a particular body surface). As a further alternative, the electrodes need not be on the body surface, but may be positioned inside the body.

[0039] exist Figure 1 , x-axis surface electrodes 12, 14 are applied to the patient along a first axis, such as on the lateral sides of the patient's thoracic region (e.g., applied to the skin under each of the patient's arms) and may be referred to as left and right electrodes. Y-axis electrodes 18, 19 are applied to the patient along a second axis generally orthogonal to the x-axis, such as along the patient's inner thigh and neck region, and may be referred to as left leg and neck electrodes. Z-axis electrodes 16, 22 are applied along a third axis generally orthogonal to both the x-axis and the y-axis, such as along the patient's sternum and spine in the thoracic region, and may be referred to as chest and back electrodes. The heart 10 is located between these surface electrode pairs 12 / 14, 18 / 19, and 16 / 22.

[0040] An additional surface reference electrode (e.g., a "belly patch") 21 provides a reference and / or ground electrode for system 8. The abdominal patch electrode 21 can be a replacement for the fixed intracardiac electrodes 31 described in more detail below. It should also be understood that, in addition, patient 11 can have most or all of the conventional electrocardiogram ("ECG" or "EKG") system leads in place. In some embodiments, for example, a standard set of 12 ECG leads can be used to sense the electrocardiogram on the patient's heart 10. This ECG information can be used by system 8 (e.g., it can be provided as input to computer system 20). Insofar as ECG leads are well understood, and for clarity in the figures, Figure 1 Only a single lead 6 and its connection to the computer 20 are shown.

[0041] Also shown is a representative catheter 13 having at least one electrode 17. This representative catheter electrode 17 is referred to throughout the specification as a "wandering electrode," "mobile electrode," or "measurement electrode." Typically, multiple electrodes 17 on the catheter 13 or on multiple such catheters will be used. For example, in one embodiment, the system 8 may include sixty-four electrodes on twelve catheters disposed within the patient's heart and / or vasculature. In other embodiments, the system 8 may utilize a single catheter that includes multiple (e.g., eight) splines, each of which in turn includes multiple (e.g., eight) electrodes.

[0042] However, the foregoing embodiments are merely exemplary, and any number of electrodes and / or catheters may be used. For example, for purposes of this disclosure, Figure 2 , and in particular, an HD grid catheter. The HD grid catheter 13 includes a catheter body 200 coupled to a paddle 202. The catheter body 200 may further include first and second body electrodes 204, 206, respectively. The paddle 202 may include a first spline 208, a second spline 210, a third spline 212, and a fourth spline 214, which are coupled to the catheter body 200 via a proximal coupler 216 and coupled to each other via a distal coupler 218. In one embodiment, the first spline 208 and the fourth spline 214 may be one continuous segment, while the second spline 210 and the third spline 212 may be another continuous segment. In other embodiments, the various splines 208, 210, 212, 214 may be separate segments coupled to each other (e.g., via proximal and distal couplers 216, 218, respectively). It should be understood that the HD catheter 13 may include any number of splines; Figure 2 The four-spline arrangement shown in is exemplary only.

[0043] As described above, the splines 208, 210, 212, 214 may include any number of electrodes 17; Figure 2 , sixteen electrodes 17 are shown arranged in a four by four array. It should also be understood that the electrodes 17 may be spaced uniformly and / or non-uniformly, as measured along and between the splines 208, 210, 212, 214. For ease of reference in this description, Figure 3A Alphanumeric labels for the electrodes 17 are provided.

[0044] As will be appreciated by one of ordinary skill in the art, any two adjacent electrodes 17 define a dipole. Thus, the 16 electrodes 17 on the catheter 13 define a total of 42 dipoles - 12 along the splines (e.g., between electrodes 17a and 17b, or between electrodes 17c and 17d), 12 across the splines (e.g., between electrodes 17a and 17c, or between electrodes 17b and 17d), and 18 along the diagonals between the splines (e.g., between electrodes 17a and 17d, or between electrodes 17b and 17c).

[0045] For ease of reference in this description, Figure 3B Alphanumeric labels are provided for along-spline and across-spline dipoles. Figure 3B Alphanumeric labels for the diagonal dipoles have been omitted, but this is only for clarity in the illustration. It is expressly contemplated that the teachings herein may also be applied to diagonal dipoles.

[0046] In turn, any of the dipoles can be used to generate a dipole electrogram according to techniques familiar to those of ordinary skill in the art. Furthermore, these dipole electrograms can be combined (e.g., linearly combined) to generate an electrogram in any direction in the plane of the catheter 13 by calculating the electric field loop for the electrode group, again including activation timing information. U.S. Application No. 15 / 953,155 (which is incorporated herein by reference as if fully set forth herein) discloses details of calculating the electric field loop for the electrode group on the HD mesh catheter.

[0047] In any case, the catheter 13 can be used to simultaneously collect multiple electrophysiological data points of various dipoles defined by the electrodes 17 thereon, each such electrophysiological data point including positioning information (e.g., the position and orientation of the selected dipole) and the electrogram signal of the selected dipole. For purposes of illustration, methods according to the present disclosure will be described with reference to individual electrophysiological data points collected by the catheter 13. However, it should be understood that the teachings herein can be applied serially and / or in parallel to multiple electrophysiological data points collected by the catheter 13.

[0048] The catheter 13 (or a plurality of such catheters) is typically introduced into the patient's heart and / or vascular system via one or more introducers and using familiar procedures. In fact, various methods of introducing the catheter 13 into the patient's heart, such as a transseptal approach, are familiar to those of ordinary skill in the art and therefore do not need to be further described herein.

[0049] Because each electrode 17 is located within the patient's body, the system 8 can collect position data for each electrode 17 simultaneously. Similarly, each electrode 17 can be used to collect electrophysiological data (e.g., surface electrograms) from the surface of the heart. Ordinary technicians will be familiar with various modes for acquiring and processing electrophysiological data points (including, for example, both contact and non-contact electrophysiological mapping), so that further discussion of them is not necessary for an understanding of the technology disclosed herein. Similarly, various techniques familiar in the art can be used to generate graphical representations of cardiac geometry and / or cardiac electrical activity from multiple electrophysiological data points. In addition, to the extent that ordinary technicians will understand how to create electrophysiological maps from electrophysiological data points, aspects thereof will be described herein only to the extent necessary for an understanding of the present disclosure.

[0050] Return now Figure 1 In some embodiments, an optional fixed reference electrode 31 (e.g., attached to the wall of the heart 10) is displayed on the second catheter 29. For calibration purposes, this electrode 31 can be fixed (e.g., attached to or near the heart wall) or arranged in a fixed spatial relationship with a wandering electrode (e.g., electrode 17), and thus can be referred to as a "navigation reference" or "local reference". The fixed reference electrode 31 can be used in addition to or in place of the surface reference electrode 21 described above. In many cases, the coronary sinus electrode or other fixed electrode in the heart 10 can be used as a reference for measuring voltage and displacement; that is, as described below, the fixed reference electrode 31 can define the origin of the coordinate system.

[0051] Each surface electrode is coupled to a multiplexing switch 24, which couples the surface electrodes to a signal generator 25, and the surface electrode pairs are selected by software running on the computer 20. Alternatively, the switch 24 may be eliminated and multiple (e.g., three) instances of the signal generator 25 may be provided, one for each measurement axis (that is, each surface electrode pair).

[0052] The computer 20 may include, for example, a conventional general purpose computer, a special purpose computer, a distributed computer, or any other type of computer. The computer 20 may include one or more processors 28, such as a single central processing unit ("CPU") or multiple processing units, commonly referred to as a parallel processing environment, which may execute instructions to practice various aspects described herein.

[0053] Typically, three nominal orthogonal electric fields are generated by a series of driven and sensed electric dipoles (e.g., surface electrode pairs 12 / 14, 18 / 19, and 16 / 22) to achieve catheter navigation in a bioconductor. Alternatively, these orthogonal fields can be decomposed, and any surface electrode pair can be driven as a dipole to provide effective electrode triangulation. Similarly, electrodes 12, 14, 18, 19, 16, and 22 (or any number of electrodes) can be positioned in any other effective arrangement to drive current to the electrodes in the heart or sense the current from the electrodes in the heart. For example, multiple electrodes can be placed on the back, side, and / or abdomen of the patient 11. In addition, such non-orthogonal methods increase the flexibility of the system. For any desired axis, the potential measured across the wandering electrodes generated by a set of predetermined drive (source-sink) configurations can be combined algebraically to produce the same effective potential as obtained by simply driving a uniform current along the orthogonal axis.

[0054] Thus, any two of the surface electrodes 12, 14, 16, 18, 19, 22 may be selected as the source and drain of a dipole with respect to a ground reference (such as an abdominal patch 21), while the unexcited electrodes measure a voltage with respect to the ground reference. A wandering electrode 17 placed in the heart 10 is exposed to the field from the current pulses and measures with respect to the ground (such as the abdominal patch 21). In practice, the catheter within the heart 10 may contain more or fewer electrodes than the sixteen shown, and the potential of each electrode may be measured. As previously described, at least one electrode may be fixed to the inner surface of the heart to form a fixed reference electrode 31, which is also measured with respect to the ground (such as the abdominal patch 21) and may be defined as the origin of a coordinate system relative to which the system 8 measures position. Data sets from each of the surface electrodes, internal electrodes, and virtual electrodes may be used to determine the position of the wandering electrode 17 within the heart 10.

[0055] The system 8 can use the measured voltages to determine the position of an electrode inside the heart (such as the wandering electrode 17) relative to a reference position (such as the reference electrode 31) in three-dimensional space. That is, the voltage measured at the reference electrode 31 can be used to define the origin of the coordinate system, and the voltage measured at the wandering electrode 17 can be used to express the position of the wandering electrode 17 relative to the origin. In some embodiments, the coordinate system is a three-dimensional (x, y, z) Cartesian coordinate system, but other coordinate systems are also contemplated, such as polar coordinate systems, spherical coordinate systems, and cylindrical coordinate systems.

[0056] As should be clear from the foregoing discussion, when the surface electrode pair applies an electric field on the heart, data for determining the position of the electrode within the heart is measured. The electrode data can also be used to create breathing compensation values ​​for improving the raw position data of the electrode position, as described, for example, in U.S. Pat. No. 7,263,397, which is incorporated herein by reference in its entirety. The electrode data can also be used to compensate for changes in the patient's body impedance, as described, for example, in U.S. Pat. No. 7,885,707, which is also incorporated herein by reference in its entirety.

[0057] Thus, in a representative embodiment, the system 8 first selects a set of surface electrodes and then drives them with current pulses. While the current pulses are being delivered, electrical activity, such as voltage measured with at least one of the remaining surface electrodes and the in vivo electrodes, is measured and stored. Compensation for artifacts such as respiration and / or impedance shifts may be performed as described above.

[0058] In aspects of the present disclosure, system 8 may be a hybrid system that combines both impedance-based (e.g., as described above) and magnetic-based positioning capabilities. Thus, for example, system 8 may also include a magnetic source 30 coupled to one or more magnetic field generators. For clarity, Figure 1 Only two magnetic field generators 32 and 33 are depicted, but it should be understood that additional magnetic field generators (e.g., a total of six magnetic field generators, defining three generally orthogonal axes, similar to the axes defined by patch electrodes 12, 14, 16, 18, 19, and 22) may be used without departing from the scope of the present teachings. Likewise, one of ordinary skill in the art will understand that one or more magnetic positioning sensors (e.g., coils) may be included in order to locate catheter 13 within the magnetic field so generated.

[0059] In some embodiments, system 8 is Abbott Laboratories' EnSite TM Velocity TM or EnSitePrecision TM Cardiac Mapping and Visualization System. However, other localization systems may be used in conjunction with the present teachings, including, for example, the RHYTHMIA HDX TM mapping systems, CARTO navigation and positioning systems from Biosense Webster, Inc. (Irvine, California), and the ADAMS system from Northern Digital Inc. (Waterloo, Ontario). Systems, Sterotaxis, Inc. (St. Louis, Missouri) Magnetic navigation system and MediGuide from Abbott Laboratories TM technology.

[0060] The positioning and mapping systems described in the following patents (all of which are incorporated herein by reference in their entirety) may also be used with the present invention: U.S. Patent Nos. 6,990,370; 6,978,168; 6,947,785; 6,939,309; 6,728,562; 6,640,119; 5,983,126; and 5,697,377.

[0061] Aspects of the present disclosure relate to electrophysiological mapping, and in particular to generating a visualization (i.e., a graphical representation) of a LAT map. Such a visualization may be output, for example, on a display 23. The system 8 may therefore include a visualization module 58 that may be used to generate a LAT map and output the LAT map (e.g., on a display 23).

[0062] Reference will be made to Figure 4 400 of representative steps is shown to explain an exemplary method according to the present teachings. For example, in some embodiments, the flowchart 400 may represent a method that can be performed by Figure 1 Several exemplary steps are performed by the electroanatomical mapping system 8 (e.g., by the processor 28 and / or the visualization module 58). It should be understood that the representative steps described below can be implemented in hardware or software. For the sake of explanation, the term "signal processor" may be used herein to describe both hardware-based and software-based implementations of the teachings herein.

[0063] In block 402, the system 8 receives a LAT data set (also referred to as a "LAT map"). As will be appreciated by one of ordinary skill in the art, the LAT data set includes a plurality of electrophysiological (EP) data points, each of which includes positioning information and an electrogram signal. For example, in an embodiment of the present disclosure, the positioning information corresponds to a mid-position of the catheter 13 during the collection of the corresponding electrogram signal.

[0064] A person of ordinary skill will also understand that the LAT data set can be graphically represented on a model of the heart surface (e.g., on the display 23). For example, U.S. Patent Application Publication No. 2007 / 0073179 (which is incorporated herein by reference as if fully set forth herein) describes the projection of electrophysiological information (including, but not limited to, LAT information) from EP data points to a heart surface model. Similarly, it is known to project electrophysiological information only from EP data points having positioning information within a preset threshold distance of the heart surface model, and discard all other EP data points, to reduce redundancy and mapping variability. Once the EP data points are projected onto the heart surface model, they can be annotated with LAT information, for example, according to U.S. Patent Application Publication No. 2019 / 0038165, which is incorporated herein by reference as if fully set forth herein.

[0065] Figure 5 A graphical representation 500 of a LAT map created using techniques familiar to those of ordinary skill in the art is shown. Figure 5 Outlier regions 502 are also depicted.

[0066] Return now Figure 4 In the flowchart 400 in FIG. 4 , in block 404, the system 8 defines one or more spatial kernels (SK). According to aspects of the present disclosure, each spatial kernel (denoted as i) is defined as a given EP data point (denoted as DxL i,0 ) is a sphere with radius r centered at . Each spatial kernel i is further defined as the kernel contained in DxL i,0 N additional EP data points within a radius r (each denoted as DxL i,j , where j is between 1 and N) (e.g., using DxL i,0 and DxL i,j The radius r may be preset by the user; in some embodiments of the present disclosure, r is approximately 5 mm.

[0067] In block 406, the system 8 calculates the spatial gradient for each defined spatial kernel. In certain embodiments of the present disclosure, a spatial kernel may be defined for each EP data point, thereby calculating the spatial kernel. For example, this Fig. 6A Shown in FIG. 6 is a spatial kernel 600.

[0068] In other embodiments of the present disclosure, the spatial kernel is defined only for a subset of EP data points, and only the spatial gradient is calculated.For example, the system 8 may accept user input to select a subset of EP data points for spatial kernel definition and spatial gradient calculation.

[0069] Alternatively, the system 8 may analytically determine a subset of EP data points for spatial kernel definition and spatial gradient calculation. For example, the system 8 may apply a filter such as vtkGradientFilter( https: / / vtk.org / doc / nightly / html / classvtkGradientFilter.html ) to identify one or more regions of high LAT gradient. Of course, computational efficiency can be improved by defining a spatial kernel and computing the spatial gradient only within these identified regions of high LAT gradient. Figure 6B , shown as spatial kernel 602, which also depicts areas of high LAT gradient as dark black patches on the heart surface model.

[0070] Regardless of the method used to define the spatial kernel (e.g., all EP data points, a user-selected subset of EP data points, an analytically determined subset of EP data points, or any other suitable method), the spatial gradient of the spatial kernel i can be calculated as SK_Grad i={LAT at DxL i,0}-median(A), where median(A) is the set A = {LAT at DxL i,j , j = 1 to N}. Note that the mean and / or standard deviation of set A can also be calculated.

[0071] In block 408, the system 8 calculates the temporal gradient (denoted as DxL) of each EP data point. l,0 ). The temporal gradient is calculated over a few ticks, e.g. about 20 seconds. Therefore, DxL l,0 The temporal kernel can be defined as including the DxL l,0 NT additional beats (each denoted as DxL) having similar electrogram signal morphology (eg, with respect to ECG and / or electrogram signals) l,m , where m is between 1 and NT). One of ordinary skill in the art will be familiar with various methods of calculating morphological similarity between signals (e.g., by using cross-correlation). However, it is also possible to consider using the peak frequency function of the signals, which will be discussed in more detail below, as a measure of morphological similarity.

[0072] When defining the temporal kernel, it is also possible to use the proximity criterion (e.g., in DxL l,0 The beat is measured at a position within about 5 mm of the

[0073] For each temporal kernel (and therefore for each EP data point), the temporal gradient can be calculated as TK_Grad l ={LAT at DxL 1,0}-median(B), where median(B) is the set B = {LAT at DxL l,m , m = 1 to NT}. Note that the mean and / or standard deviation of set B can also be calculated.

[0074] The system 8 detects outliers in block 410. More specifically, the system 8 detects spatial outliers using the spatial gradients calculated in block 406 and detects temporal outliers using the temporal gradients calculated in block 408. In either case, the system 8 can detect outliers by applying the calculated spatial gradients (e.g., SK_Grad i ) or time gradient (e.g., TK_Grad l ) is compared with the corresponding spatial gradient threshold or temporal gradient threshold, and the anchor spatial kernel (e.g., DxL i,0 ) or temporal kernels (e.g., DxL l ,0 ) is an outlier; an anchor EP data point can be identified as an outlier if the calculated spatial or temporal gradient exceeds the corresponding threshold.

[0075] In some aspects of the present disclosure, the spatial gradient threshold and / or the temporal gradient threshold are user preset values, such as approximately 50 ms. In other aspects of the present disclosure, the spatial gradient threshold and / or the temporal gradient threshold are calculated as the scaled median absolute deviation (MAD) of set A and set B, respectively. In a specific embodiment of the present disclosure, MAD(A)=c*median(|LAT atDxL i,j -median(A)|), for j=1 to N; and MAD(B)=c*median(|LAT at DxL l,m -median(B)|), for m=1 to NT, where c=1.4826.

[0076] The system 8 corrects the outliers in block 412. In some embodiments, the system 8 applies a LAT value dispersion algorithm to correct the outliers. Spatial outlier EP data point DxL i,0 The electrogram signal is windowed using mean(A)±std_dev(A), and the temporal outlier EP data point DxL l,0 The electrogram signals were windowed using mean(B)±std_dev(B). Figure 7 An electrogram signal 700 is shown with outlier EP data points windowed 702 as described above.

[0077] In other embodiments, system 8 applies a peak frequency dispersion algorithm to correct outliers. Figure 8 The peak frequency dispersion algorithm is shown. First, a one-dimensional energy function L(t) 800 of the electrogram 802 of the spatial and / or temporal kernel of the outlier EP data points is calculated, for example, as disclosed in U.S. Patent Application Publication No. 2019 / 0038165. Each energy function 800 is then converted to a step function 804 Once all step functions L are calculated for a particular kernel Pulse (t), then the overlap function 806L is calculated Pulse (t)_overlap.

[0078] Next, we use Boolean operations to combine the step functions L Pulse (t) and the overlap function L Pulse (t)_overlap, to identify the function L Pulse (t)_common (e.g., 808) common subset. Pulse (t)_common 808 is applied to the electrogram signal 810 for the anomalous EP data points that are in the window 812 of interest.

[0079] Under either approach, a corrected LAT for outlier EP data points may be calculated on the windowed electrogram signal, for example using the teachings of U.S. Patent Application Publication No. 2019 / 0038165.

[0080] If neither the LAT value dispersion nor the peak frequency dispersion can produce a valid corrected LAT, median(A) can be used as the corrected LAT for spatial outlier EP data points, while median(B) can be used as the corrected LAT for temporal outlier EP data points.

[0081] The spatial outlier EP data point LAT may also be smoothed in block 414. According to embodiments disclosed herein, the LAT at the spatial outlier EP data point is smoothed by applying a Gaussian distribution to the corresponding spatial kernel. i,0 The smoothed LAT at can be calculated as in exp is an exponent, μ and σ are user preset parameters for controlling the shape of the Gaussian distribution. In the embodiment of the present disclosure, μ and σ are approximately 1.0 and approximately 2.0, respectively.

[0082] like Fig. 9A and 9B As shown, the system 8 outputs a graphical representation of the corrected LAT map in box 416. In particular, Fig. 9A A graphical representation 900 of a corrected LAT map is shown, and Fig. 9B A graphical representation 902 of a corrected and smoothed LAT map is shown.

[0083] Although several embodiments have been described above with a certain degree of particularity, those skilled in the art could make numerous alterations to the disclosed embodiments without departing from the spirit or scope of the invention.

[0084] For example, the teachings herein may be applied in real-time (eg, during an electrophysiological study) or during post-processing (eg, to electrophysiological data points collected during an electrophysiological study performed at an earlier time).

[0085] All directional references (e.g., up, down, upward, downward, left, right, leftward, rightward, top, bottom, above, below, vertical, horizontal, clockwise, and counterclockwise) are used for identification purposes only to aid the reader's understanding of the present invention, and are not intended to limit the position, orientation, or use of the present invention in particular. References to conjunction (e.g., attached, coupled, connected, etc.) should be interpreted broadly and may include intermediate members between the connection of elements and relative movement between elements. Thus, references to conjunction do not necessarily infer that two elements are directly connected and in fixed relation to each other.

[0086] It is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative only and not limiting. Changes in detail or structure may be made without departing from the spirit of the invention as defined in the appended claims.

Claims

1. A method for graphically representing a local activation time LAT, the method comprising: receiving, at an electroanatomical mapping system, a LAT data set comprising a plurality of electrophysiological EP data points, wherein each EP data point of the plurality of EP data points comprises localization information and an electrogram signal; the electroanatomical mapping system calculating a spatial gradient on a spatial kernel, the spatial kernel being defined as a sphere of radius r centered at an EP data point of the plurality of EP data points of the LAT data set and being defined as including additional EP data points within radius r; the electroanatomical mapping system calculating a plurality of time gradients by calculating a corresponding time gradient for each of a plurality of time kernels over a plurality of beats, wherein each of the plurality of time kernels is defined to include an electrogram signal of the EP data point of the plurality of EP data points and is defined to include an additional beat, wherein the additional beat has a similar morphology to the electrogram signal of the EP data point of the plurality of EP data points; The electroanatomical mapping system detects spatial outlier EP data points within the spatial kernel using the spatial gradient; The electroanatomical mapping system detects temporal outlier EP data points using the plurality of temporal gradients; The electroanatomical mapping system corrects the spatial outlier EP data points and the temporal outlier EP data points to create a corrected LAT map; and The electroanatomical mapping system outputs a graphical representation of the corrected LAT map on a heart surface model.

2. The method according to claim 1, wherein: Receiving a LAT data set including a plurality of electrophysiological EP data points at an electroanatomical mapping system includes: projecting each EP data point onto the heart surface model using the positioning information of the corresponding EP data point; and A LAT is assigned to each projected EP data point using the electrogram signal of the corresponding EP data point.

3. The method according to claim 1, wherein: The electroanatomical mapping system calculates a spatial gradient on a spatial kernel centered at an EP data point among the plurality of EP data points of the LAT data set, comprising: defining a spatial kernel for each EP data point in the plurality of EP data points; and The spatial gradient is calculated for each defined spatial kernel.

4. The method according to claim 1, wherein: The electroanatomical mapping system calculates a spatial gradient on a spatial kernel centered at an EP data point among the plurality of EP data points of the LAT data set, comprising: The electroanatomical mapping system accepts user input selecting a subset of the plurality of EP data points; defining a spatial kernel for each EP data point of a subset of the plurality of EP data points; and The spatial gradient is calculated for each defined spatial kernel.

5. The method according to claim 1, wherein: The electroanatomical mapping system calculates a spatial gradient on a spatial kernel centered at an EP data point among the plurality of EP data points of the LAT data set, comprising: The electroanatomical mapping system identifies regions of high LAT gradient in the LAT dataset; defining a spatial kernel for each EP data point within the region of high LAT gradient; and The spatial gradient is calculated for each defined spatial kernel.

6. The method according to claim 1, wherein: Detecting, by the electroanatomical mapping system, spatial outlier EP data points within the spatial kernel using the spatial gradient includes the electroanatomical mapping system detecting the spatial outlier EP data points by comparing the spatial gradient to a spatial gradient threshold.

7. The method according to claim 6, wherein: The spatial gradient threshold includes a user preset value.

8. The method according to claim 6, wherein: The spatial gradient threshold comprises a calculated scaled mean absolute deviation value.

9. The method according to claim 1, wherein: Detecting, by the electroanatomical mapping system, a temporal outlier EP data point using the plurality of temporal gradients includes the electroanatomical mapping system detecting the temporal outlier EP data point by comparing the plurality of temporal gradients to a temporal gradient threshold.

10. The method according to claim 9, wherein: The time gradient threshold includes a user preset value.

11. The method according to claim 9, wherein: The temporal gradient threshold comprises a calculated scaled mean absolute deviation value.

12. The method according to claim 1, wherein: The electroanatomical mapping system correcting the spatial outlier EP data points and the temporal outlier EP data points to create a corrected LAT map includes the electroanatomical mapping system applying at least one of a LAT value dispersion algorithm and a peak frequency dispersion algorithm to the spatial outlier EP data points and the temporal outlier EP data points.

13. The method of claim 1, further comprising the electroanatomical mapping system spatially smoothing the LAT dataset.

14. The method according to claim 13, wherein: The electroanatomical mapping system spatially smoothing the LAT dataset includes applying a Gaussian distribution to the spatial kernel.

15. A method for graphically representing a local activation time LAT, comprising: receiving, at an electroanatomical mapping system, a LAT map comprising a plurality of electrophysiological EP data points; the electroanatomical mapping system calculating a spatial gradient over a spatial kernel, the spatial kernel being defined as a sphere of radius r centered at an EP data point of the plurality of EP data points of the LAT map and being defined as including additional EP data points within radius r; the electroanatomical mapping system calculating a corresponding temporal gradient for each of a plurality of temporal kernels over a plurality of beats, wherein each of the plurality of temporal kernels is defined to include an electrogram signal of the EP data point of the plurality of EP data points and is defined to include an additional beat, wherein the additional beat has a similar morphology to the electrogram signal of the EP data point of the plurality of EP data points; as well as the electroanatomical mapping system identifying at least one of a spatial outlier EP data point and a temporal outlier EP data point within the plurality of EP data points using the calculated spatial gradient and the calculated temporal gradient; The electroanatomical mapping system corrects at least one of the identified spatial outlier EP data points and the temporal outlier EP data points to create a corrected LAT map; and The electroanatomical mapping system outputs a graphical representation of the corrected LAT map on a heart surface model.

16. The method according to claim 15, wherein: The electroanatomical mapping system corrects at least one of the identified spatial outlier EP data points and the temporal outlier EP data points to create a corrected LAT map, including the electroanatomical mapping system applying at least one of a LAT value dispersion algorithm and a peak frequency dispersion algorithm to at least one of the spatial outlier EP data points and the temporal outlier EP data points.

17. A system for graphically representing a local activation time (LAT), comprising: The visualization module is configured to: receiving a LAT data set including a plurality of electrophysiological EP data points, wherein each EP data point of the plurality of EP data points includes positioning information and an electrogram signal; calculating a spatial gradient on a spatial kernel, the spatial kernel being defined as a sphere of radius r centered at an EP data point of the plurality of EP data points of the LAT data set and being defined as including additional EP data points within radius r; calculating a plurality of time gradients by calculating a corresponding time gradient for each of a plurality of time kernels over a plurality of beats, wherein each of the plurality of time kernels is defined to include an electrogram signal of the EP data point of the plurality of EP data points and is defined to include an additional beat, wherein the additional beat has a similar morphology to the electrogram signal of the EP data point of the plurality of EP data points; Detecting spatial outlier EP data points within the spatial kernel using the spatial gradient; detecting temporal outlier EP data points using the plurality of temporal gradients; correcting the spatial outlier EP data points and the temporal outlier EP data points to create a corrected LAT map; and A graphical representation of the corrected LAT map is output on a heart surface model.

18. The system of claim 17, wherein: The visualization module is configured to: identifying regions of high LAT gradient within the LAT dataset; and A plurality of spatial gradients are calculated over a corresponding plurality of spatial kernels, each of the plurality of spatial kernels being centered at a corresponding EP data point within the region of high LAT gradient.

19. The system of claim 17, wherein: The visualization module is configured to correct the spatial outlier EP data points and the temporal outlier EP data points by applying at least one of a LAT value dispersion algorithm and a peak frequency dispersion algorithm to the spatial outlier EP data points and the temporal outlier EP data points.

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