Mapping of a heart chamber having regions exhibiting fragmented electrograms

Abstract

The invention is entitled "Propagation mapping of a heart chamber with regions exhibiting fragmented electrograms". The invention provides a method comprising storing an anatomical map of at least a portion of a surface of a heart. Storing respective electrogram (EGM) signal amplitudes measured at respective locations on the surface of the heart. Defining one or more first regions of the surface where the EGM signal amplitudes are fragmented and one or more second regions of the surface where the EGM signal amplitudes are non-fragmented based on the EGM signal amplitudes. Generating a first surface representation of the fragmented EGM signal amplitudes in the first regions. Extracting propagation times from the non-fragmented EGM signal amplitudes in the second regions and deriving a second surface representation of the propagation times. Presenting simultaneously the first and second surface representations of the respective first and second regions of the surface superimposed on the anatomical map.

Description

Technical Field

[0001] This invention relates generally to electrophysiological mapping, and more specifically to the visualization of cardiac electrophysiological mapping. Background Technology

[0002] Electrophysiological (EP) cardiac mapping can utilize visualization methods previously proposed in patent literature to simplify the interpretation of EP mapping maps. For example, U.S. Patent 8,838,216 describes a method for generating a model of the cardiac surface having multiple images representing electrogram voltages at multiple measurement points within the heart. The method includes: measuring electrogram voltages at multiple points within the heart; generating a first model of the cardiac surface; generating an image representing each electrogram voltage, each image having features representing the electrogram voltage; and generating another model of the cardiac surface. Points on the other model representing the electrogram voltages, corresponding to the points where the electrogram voltages are measured, protrude from the other model of the cardiac surface. An apparatus for generating a model of the cardiac surface is also disclosed.

[0003] For example, U.S. Patent Application Publication 2009 / 0192393 describes software and apparatus for automatically detecting and mapping neural plexuses within complex, fragmented atrial electrocardiogram (CFAE) regions present in the heart chambers during atrial fibrillation (AFib). The electrocardiogram signal is analyzed to count the number of complex waves whose amplitude and peak-to-peak intervals meet specific criteria. A functional mapping map is generated for display, indicating the spatial distribution of the neural plexuses and the relative number of complex, fragmented electrocardiograms.

[0004] U.S. Patent Application Publication 2014 / 0005563 describes a method for visualizing electrophysiological information, which may include electroanatomical data representing electrical activity over an anatomical region within a patient's body over a period of time. Intervals within this time period are selected in response to user selection. A visual representation of the physiological information for the user-selected intervals can be generated by applying at least one analytical method to the electroanatomical data. This visual representation can be spatially superimposed on a graphical representation of the anatomical region within the patient's body. In one embodiment of the invention, the degree of fragmentation can be spatially displayed as a 3D complex fragmentation electromigration map. The lowest to highest degree of fragmentation can be visually identified using a color mapping map. Summary of the Invention

[0005] Embodiments of the present invention provide a method comprising storing an anatomical mapping of at least a portion of the surface of the heart. The method includes storing corresponding electrogrammage (EGM) signal amplitudes measured at corresponding locations on the surface of the heart. The surface is defined based on the EGM signal amplitudes: one or more first regions of the surface where the EGM signal amplitudes are fragmented, and one or more second regions of the surface where the EGM signal amplitudes are non-fragmented. A first surface representation is generated in the first regions for the fragmented EGM signal amplitudes. In the second regions, a propagation time is extracted from the non-fragmented EGM signal amplitudes, and a second surface representation of the propagation time is derived. The first and second surface representations of the corresponding first and second regions of the surface are simultaneously superimposed on the anatomical mapping.

[0006] In some implementations, the method also includes generating a third surface representation for signals that are neither limited to fragmentation nor time-limited.

[0007] In one implementation, generating a first surface for fragmented EGM signal amplitudes means selecting a subset of fragmented EGM signal amplitudes and generating a surface for that subset.

[0008] In some embodiments, the first surface represents a geometry that protrudes from that surface. In some embodiments, the geometry of the protrusion includes one of corrugations and stripes.

[0009] In one implementation, the second surface may include a color scale.

[0010] In some implementations, the propagation time includes the Local Activation Time (LAT) value.

[0011] In one embodiment, the method further includes assigning a local activation time (LAT) value to the EGM signal even if the EGM signal is fragmented, and generating a third surface representation for the fragmented EGM signal to visualize the third surface representation.

[0012] In another implementation, the propagation time includes a period length value.

[0013] According to another embodiment of the invention, a system including a memory and a processor is also provided. The memory is configured to store an anatomical mapping of at least a portion of the surface of the heart, and to store corresponding electrogrammage (EGM) signal amplitudes measured at corresponding locations on the surface of the heart. The processor is configured to: (i) define one or more first regions of the surface where the EGM signal amplitude is fragmented and one or more second regions of the surface where the EGM signal amplitude is non-fragmented, based on the EGM signal amplitudes; (ii) generate a first surface representation for the fragmented EGM signal amplitudes in the first regions; (iii) extract the propagation time from the non-fragmented EGM signal amplitudes in the second regions and derive a second surface representation of the propagation time; and (iv) simultaneously present the first and second surface representations of the corresponding first and second regions of the surface superimposed on the anatomical mapping. Attached Figure Description

[0014] The invention will be more fully understood through the following detailed description of embodiments thereof, taken in conjunction with the accompanying drawings, wherein:

[0015] Figure 1 This is a schematic diagram of a catheter-based cardiac navigation and electrophysiological (EP) signal analysis system according to an exemplary embodiment of the present invention;

[0016] Figure 2 A graph illustrating a well-defined electrogram (EGM) signal relative to a fragmented electrogram (EGM) signal according to an exemplary embodiment of the present invention is provided.

[0017] Figure 3 This is a schematic diagram of a hybrid representation of an EP mapping superimposed on cardiac anatomy, according to an exemplary embodiment of the present invention; and

[0018] Figure 4 To illustrate, an exemplary embodiment of the invention is used for generating... Figure 3 The flowchart shows the method and algorithm for hybrid representation of EP mapping. Detailed Implementation

[0019] Overview

[0020] Cardiac arrhythmias are a group of clinical conditions characterized by irregular heartbeats. These arrhythmias include important types such as ventricular tachycardia, atrial tachycardia, and fibrillation.

[0021] To characterize a patient's cardiac arrhythmias, catheter-based electrophysiological (EP) mapping systems can be used to generate EP maps of at least a portion of the patient's heart, such as EP maps of the heart chambers. In a typical catheter-based EP mapping procedure, the distal end of a catheter, including one or more sensing electrodes, is inserted into the heart chamber to sense EP signals. As the physician operating the system moves the distal end within the heart chamber, the EP mapping system acquires EP signals at various locations on the inner surface of the heart chamber and corresponding locations at the distal end. Based on these acquired signals, the mapping system's processor generates the desired EP map, such as a map including local activation time (LAT) superimposed on an anatomical map of the heart chamber.

[0022] LAT mapping typically includes areas showing normal cyclic electrical activity (e.g., sinus rhythm), areas showing abnormally rapid cyclic electrical activity (e.g., trochanteric), and areas showing complex fragmented electrograms in pathological tissue. However, in areas primarily exhibiting sinus rhythm and tachycardia, the periodicity of normal electrograms, episodes of rapid cyclic electrograms, and the presence of complex fragmented electrograms can be observed temporally.

[0023] LAT mapping can therefore indicate the presence of abnormal but well-defined propagation characteristics of the EP signal. For example, LAT mapping can indicate reentrant tachycardia (RT) by showing the region in which the EP activation wave propagates in the closed loop with a well-defined but pathological period length (e.g., the time between consecutive peaks on an electrocardiogram).

[0024] However, in some cases, EP anomalies can be manifested by outbreaks in which the electrogram is fragmented (e.g., composed of bursts of irregular patterns such as highly rapid deflections of the signal), making the time the EP wave passes under the acquisition electrode unpredictable (or practically non-occurring). In the context of this invention, the term "fragmented electrogram" refers to a non-periodic electrogram that does not have a characteristic periodic time and, in some cases, does not even have a definable peak for deriving LAT values.

[0025] For locations exhibiting fragmented electrograms, EP propagation mapping based on LAT values ​​or cycle times is practically useless because it is difficult to calculate meaningful LAT values ​​from such electrogram signals. Furthermore, the presence of fragmented electrograms has been found to be clinically significant, and therefore their presentation on EP mapping is considered important for accurately assessing underlying EP pathology.

[0026] One possible way to integrate fragmented signals into an EP mapping is to use a time-dependent “ripple” mapping, where the instantaneous EP amplitude is shown as a function of time, for example, by being presented as time-varying bars protruding from the surface of the heart chamber. In such a representation, the length (height) of each bar indicates the voltage measured at the corresponding location on the surface of the heart chamber at a given time. However, applying ripple mapping to the entire heart chamber is generally computationally intensive and visually too complex to interpret, and may also impair the clarity of other important EP information (e.g., LAT information), as this information may be omitted or obscured in such mappings.

[0027] To overcome the aforementioned challenges, exemplary embodiments of the invention described below divide the cardiac chamber mapping into fragmented and non-fragmented regions, and simultaneously integrate two different types of displays into the mapping. In some exemplary embodiments, a hybrid representation of the EP mapping is provided, wherein well-defined EP propagation characteristics (e.g., LAT values) and fragmented EP signal amplitudes are superimposed on the cardiac anatomy using different graphical representations, without obscuring the other. This process generally follows the steps in which the processor performs the following operations:

[0028] 1. Generate an EP mapping map comprising an anatomical mapping map encoding one or more first regions of fragmented EP activity and one or more second regions of well-defined EP activity, and use data analysis methods such as deep learning or clustering to depict different regions on the anatomical structure. A processor is used to define one or more first regions and one or more second regions of the surface based on the amplitude of an electrogrammation (EGM) signal, as described below. The processor then generates a first surface representation for the fragmented EGM signal amplitude in the first region, extracts the propagation time from the non-fragmented EGM signal amplitude in the second region, and derives a second surface representation of that propagation time. Finally, the processor simultaneously presents the first and second surface representations of the corresponding first and second regions of the surface superimposed on the anatomical mapping map.

[0029] 2. When a user requests a propagation mapping, the processor displays a conventional propagation mapping (e.g., derived from LAT values) on non-fragmented areas and simultaneously displays a ripple mapping on fragmented areas.

[0030] Traditional propagation mapping consists of moving highlights, hues, colors, or other visual indicators propagating based on the LAT values ​​of points. Generally, each point has one LAT value; however, some points can have multiple LAT values, for example, a two-potential point can have two LAT values. If the system is designed to have at most one LAT value at each point, a traditional propagation mapping highlights each point at most once. If the system is designed to assign multiple LAT values ​​to some points, a traditional propagation mapping can highlight some points multiple times.

[0031] In another exemplary embodiment, the processor generates a third surface representation, such as presenting a dual potential, for a signal that is neither limited to fragmentation nor limited by propagation time.

[0032] In yet another exemplary implementation, the processor selects only a subset of signals that it considers fragmented to be represented by the first surface.

[0033] In some cases, even if an EGM signal is fragmented, it can still be approximated or otherwise assigned a LAT value. In an exemplary embodiment, the processor is also configured to generate different surface representations of such fragmented EGM signals. In this exemplary embodiment, the fragmented signal can be represented by ripples and / or LAT-value-based mapping representations.

[0034] The hybrid representation of the EP mapping disclosed in this invention is substantially dynamic and can, for example, display regions exhibiting time-dependent fragmented and non-fragmented electrogram (EGM) characteristics in a video mode of the hybrid mapping.

[0035] By displaying fragmented and non-fragmented EGM feature maps using different graphical methods (e.g., ripples and color scales) on cardiac anatomy, the hybrid representation EP mapping technique disclosed in this invention can improve the diagnostic value of catheter-based EP mapping procedures.

[0036] System Description

[0037] Figure 1This is a schematic illustration of a catheter-based cardiac navigation and electrophysiological (EP) signal analysis system 20 according to an exemplary embodiment of the present invention. System 20 can be configured to analyze substantially any physiological parameter or combination of such parameters. In the description herein, by way of example, it is assumed that the signals being analyzed are intracardiac electrograms (EGM) and / or extracardiac (surface) electrocardiograms (ECG) potential-time relationships. To adequately characterize such relationships, signals at various locations need to be temporally referenced to each other, such as during the generation of a Local Activation Time (LAT) mapping. Temporal reference is accomplished by measuring relative to a reference time (e.g., a moment) (such as the start of each QRS complex of an ECG reference signal (i.e., the start of each heartbeat)). In an exemplary embodiment, the reference signal is received from a catheter placed in the coronary sinus. A method for generating a LAT mapping is described in U.S. Patent 9,050,011, the entire disclosure of which is incorporated herein by reference.

[0038] For the sake of brevity and clarity, unless otherwise specified, the following description assumes that system 20 uses probe 24 to measure the actual electrical activity of the heart 34 as part of a research procedure. It is assumed that the distal end 32 of the probe has an electrode 22. In other uses, the measured signals are used to create a LAT mapping of at least a portion of the wall tissue of the heart 34 of the patient 26.

[0039] Typically, probe 24 includes a catheter that is inserted into patient 26 during a mapping procedure performed by physician 28 using system 20. During this procedure, it is assumed that ground electrode 23 is attached to patient 26. Additionally, it is assumed that electrode 29 is attached to the skin of patient 26 in the region of heart 34.

[0040] In an exemplary embodiment, probe 24 acquires the EGM as it moves over a portion of the heart chamber. Some features in the measured EGM trace are marked when an anomalous EP activation wave passes beneath the catheter electrode. In these cases, the position of probe 24 is also recorded.

[0041] System 20 may be controlled by system processor 40, which includes processing unit 42 in communication with memory 44. In some embodiments, memory 44, included in system processor 40, stores LAT and / or voltage mapping maps 62 of at least a portion of the wall tissue of patient 26's heart 34. Processor 40 is typically mounted in console 46, which includes operating controls 38, which typically include pointing devices 39, such as a mouse or trackball, for physician 28 to interact with the processor.

[0042] Processor 40 (specifically, processing unit 42) runs software including probe tracker module 30, ECG module 36, and EP activation analysis module 35 to operate system 20 and / or cause EP activation analysis module 35 to run at least a portion of the disclosed analysis (using, for example, LAT or adjusted LAT mapping 62 stored in memory 44) in order to model arrhythmias.

[0043] ECG module 36 is coupled to receive actual electrical signals from electrodes 22 and 29. The module is configured to analyze the actual signals and can present the results of the analysis on display 48 in a standard ECG format (typically a time-shifted graphical representation).

[0044] The probe tracker module 30 typically tracks the position of the distal end 32 of the probe 24 within the heart 34 of the patient 26. The tracker module 30 can use any method known in the art for position tracking of probes. For example, the module 30 can operate a magnetic field-based position tracking subsystem. For simplicity, components of such a subsystem are not described in the text. Figure 1 As shown in the image.

[0045] Alternatively or otherwise, the tracker module 30 can track the probe 24 by measuring the impedance between electrodes 23, 29, and 22, as well as the impedance to other electrodes that may be located on the probe. In this case, electrodes 22 and / or 29 can provide both ECG and position tracking signals. Manufactured by Biosense-Webster (Irvine, California) The system uses both magnetic field position tracking and impedance measurement for position tracking.

[0046] Using tracker module 30, processor 40 is able to measure the position of distal end 32. Furthermore, using both tracker module 30 and ECG module 36, processor is able to measure the position of distal end and the LAT of the actual electrical signals detected at these specific locations. As described above, the electrical tracking signal from a single electrode 22 can be integrated with the magnetic tracking signal, such that the position of each electrode is recorded. This type of combined (i.e., magnetic / electrical) tracking system and method is suitable for various medical applications (e.g., in CARTO manufactured by Biosense-Webster Inc.). TM The Advanced Current Positioning (ACL) system implemented in the system is described in detail in U.S. Patent 8,456,182, the disclosure of which is incorporated herein by reference.

[0047] The results of the operations performed by the processor 40 are presented to the physician 28 on the display 48, which typically presents the physician with a graphical user interface, a visual representation of the ECG signals sensed by the electrodes 22, and / or an image or mapping of the heart 34 being studied.

[0048] For example, the software running on processor 40 may be downloaded to processor 40 electronically via a network, or alternatively or otherwise, it may be provided and / or stored on a non-transitory tangible medium such as magnetic storage, optical storage, or electronic storage. Specifically, processor 40 runs a dedicated algorithm that enables processor 40 to perform the steps disclosed in this invention, as described below.

[0049] Fragmented electrogram (EGM) signal

[0050] Figure 2 The diagram illustrates (i) a well-defined electrogrammage (EGM) signal 50 relative to (ii) a fragmented electrogrammage (EGM) signal 55 according to an exemplary embodiment of the invention. As shown, the well-defined EGM signal defines a time period length 52, whereas at the cardiac location showing an episode of fragmentation with an EGM signal, the time period length is not defined. The cardiac location showing such an interrupted EGM signal can be a source of arrhythmic activity requiring ablation to treat the resulting arrhythmia. However, it is complicated by the fact that both the cardiac location showing a well-defined time period length and the cardiac location showing an episode of fragmentation with an EGM signal have significant clinical value in diagnosing arrhythmias.

[0051] To address this challenge, exemplary embodiments of the disclosed invention provide graphical techniques to present two types of EP information on the same EP mapping, making it easier for physicians to analyze and diagnose complex abnormal cardiac activity.

[0052] Propagation mapping of cardiac chambers showing areas exhibiting fragmented electrorecordination.

[0053] Figure 3 This is a schematic breakdown rendering of a hybrid representation EP mapping map 60 superimposed on cardiac anatomy according to an exemplary embodiment of the present invention. As shown, the hybrid representation EP mapping map 60 includes a first surface representation 61 of fragmented regions and a second surface representation 62 of non-fragmented (i.e., well-defined) regions.

[0054] In regions such as region 61 (where time analysis is not possible due to EGM signals acquired at the location of the fractured surface), the mixed representation EP mapping 60 provides a visualization of the amplitude of the fracture superimposed on the anatomical structure in the form of bars 63 protruding from the surface, where the height of the bar represents the magnitude of the EGM amplitude at that location at a given time.

[0055] The second surface representation 62 encodes propagation time values ​​(e.g., LAT values) in the form of a color-coded rendering map 64 (shown in grayscale) on a region of the anatomical mapping (such as region 62), where the color of the surface location gives the LAT value of that location at a given time.

[0056] The hybrid representation EP mapping map 60 should be understood as a "snapshot" of time-dependent EP activity, and is typically displayed using video mode.

[0057] Figure 4 To illustrate, an exemplary embodiment of the invention is used for generating... Figure 3 A flowchart of a method and algorithm for a hybrid representation of EP mapping map 60 is provided. According to the provided exemplary embodiment, the algorithm performs the following process, which begins at the step 70 where processor 40 uploads anatomical mapping maps of the cardiac chambers and EP mapping data (e.g., EGM sets from surface locations on the mapped anatomical structures) from memory 44.

[0058] Next, at EGM analysis step 72, processor 40 determines which EGMs among the uploaded EGMs are fragmented and which EGMs are well-defined (e.g., non-fragmented).

[0059] At step 74 of the EP mapping generation, the processor 40 generates an EP mapping that includes an anatomical mapping encoded using one or more first regions of fragmented EP activity and one or more second regions of well-defined EP activity, and depicts different regions on the anatomical structure.

[0060] At step 76 of the EP mapping presentation, processor 40 presents the EP mapping depicted in step 74 to the user (e.g., physician 28) on display 48. At this time, physician 28 may require more information, such as displaying a propagation mapping including LAT values ​​or cycle lengths at the propagation mapping request step 78.

[0061] In order to preserve fragmented EP activity information without obscuring the propagated information, processor 40 derives the aforementioned hybrid representation of EP mapping map 60.

[0062] At step 80 of the EP data analysis, processor 40 extracts the signal amplitude from the fragmented EGM signal and the amplitude propagation time, such as the LAT value or period length, from the non-fragmented EGM signal. Finally, at step 82, processor 40 constructs a hybrid representation of the EP mapping map 60, in which certain parts of the anatomy are superimposed with discrete representations (e.g., raised bars 68) to show fragmented EP activity, while other parts of the anatomy are superimposed with well-defined continuous-time information of the EP activity (e.g., color-coded regions 64).

[0063] It should be understood that the above embodiments are cited by way of example, and the invention is not limited to what has been specifically shown and described above. Rather, the scope of the invention includes combinations and sub-combinations of the various features described above, as well as variations and modifications thereof, which will occur to those skilled in the art upon reading the above description and which are not disclosed in the prior art. Documents incorporated herein by reference are considered an integral part of this application, except that if any terminology defined in such incorporated documents conflicts with the definitions expressly or implicitly given in this specification, only the definitions in this specification shall be considered.

Claims

1. A method for characterizing cardiac arrhythmias, the method comprising: Store anatomical mappings of at least a portion of the surface of the heart; The amplitude of the corresponding electrogram (EGM) signal, measured at the corresponding location on the surface of the heart; The surface is defined based on the EGM signal amplitude, wherein the EGM signal amplitude is one or more first regions of the surface that are fragmented and wherein the EGM signal amplitude is one or more second regions of the surface that are not fragmented. A first surface representation is generated for the fragmented EGM signal amplitude in the first region; The propagation time is extracted from the non-fragmented EGM signal amplitude in the second region, and a second surface representation of the propagation time is derived. as well as Simultaneously, the first surface representation and the second surface representation of the corresponding first and second regions of the surface are presented superimposed on the anatomical mapping.

2. The method of claim 1, further comprising generating a third surface representation for signals that are neither defined as fragmented nor limited by propagation time.

3. The method of claim 1, wherein generating the first surface for the fragmented EGM signal amplitudes represents selecting a subset of the fragmented EGM signal amplitudes and generating the surface for the subset.

4. The method of claim 1, wherein the first surface represents a geometry including protrusions from the surface.

5. The method of claim 2, wherein the geometry of the protrusion includes one of corrugations and stripes.

6. The method of claim 1, wherein the second surface represents a color mark.

7. The method of claim 1, wherein the propagation time includes a Local Activation Time (LAT) value.

8. The method of claim 1, further comprising assigning a Local Activation Time (LAT) value to the EGM signal even if the EGM signal is fragmented, and generating a third surface representation for the fragmented EGM signal to visualize the third surface representation.

9. The method according to claim 1, wherein the propagation time includes a period length value.

10. A system for characterizing cardiac arrhythmias, the system comprising: The memory is configured to: Store anatomical mappings of at least a portion of the surface of the heart; as well as The amplitude of the corresponding electrogram (EGM) signal, measured at the corresponding location on the surface of the heart; and Processor, the processor being configured to: The surface is defined based on the EGM signal amplitude, wherein the EGM signal amplitude is one or more first regions of the surface that are fragmented and wherein the EGM signal amplitude is one or more second regions of the surface that are not fragmented. A first surface representation is generated for the fragmented EGM signal amplitude in the first region; The propagation time is extracted from the non-fragmented EGM signal amplitude in the second region, and a second surface representation of the propagation time is derived. as well as Simultaneously, the first surface representation and the second surface representation of the corresponding first and second regions of the surface are presented superimposed on the anatomical mapping.

11. The system of claim 10, wherein the processor is further configured to generate a third surface representation for a signal that is neither limited to fragmentation nor limited by propagation time.

12. The system of claim 10, wherein the processor is configured to generate the first surface representation for the fragmented EGM signal amplitudes by selecting a subset of the fragmented EGM signal amplitudes and generating the surface for the subset.

13. The system of claim 10, wherein the first surface represents a geometry including protrusions from the surface.

14. The system of claim 11, wherein the geometry of the protrusion includes one of corrugations and stripes.

15. The system of claim 10, wherein the second surface represents a color mark.

16. The system of claim 10, wherein the propagation time includes a Local Activation Time (LAT) value.

17. The system of claim 10, wherein the processor is configured to assign a Local Activation Time (LAT) value to the EGM signal even if the EGM signal is fragmented, and to generate a third surface representation for the fragmented EGM signal to visualize the third surface representation.

18. The system of claim 10, wherein the propagation time includes a period length value.

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