Visually distinguishing primary from secondary activation on electrophysiological maps

Abstract

The present invention is entitled "Visually Distinguishing Primary and Secondary Activations on an Electrophysiological Map." The present invention provides a method comprising receiving an anatomical map of at least a portion of a heart. For at least one region of the anatomical map, receiving a location and a corresponding bipolar intracardiac electrogram (EGM) signal measured at the location. Identifying primary and secondary activations in the bipolar intracardiac EGM signal. Deriving a surface representation of the bipolar intracardiac EGM signal over the region, including the identified primary and secondary activations. Presenting the surface representation superimposed on the anatomical map.

Description

Technical Field

[0001] The present invention relates generally to electrophysiological mapping, and in particular to visualization of cardiac electrophysiological maps. Background Art

[0002] Methods for visualizing mapped cardiac electrophysiological (EP) signals have been previously proposed in the patent literature. For example, U.S. Patent Application Publication No. 2010 / 0268059 describes a method that includes accessing cardiac information acquired via a catheter positioned at various locations in the venous network of a patient's heart. The cardiac information includes positional information, electrical information, and mechanical information. The method maps local electrical activation times to anatomical locations to generate an electrical activation time map. The method maps local mechanical activation times to anatomical locations to generate a mechanical activation time map. The method also generates an electromechanical delay map by subtracting the local electrical activation times from the corresponding local mechanical activation times, and plots at least the electromechanical delay map on a display.

[0003] As another example, U.S. Patent Application Publication No. 2012 / 0237093 describes a method comprising establishing a one-to-one correspondence between a location on a three-dimensional surface of a body cavity and a coordinate representing the location in a two-dimensional coordinate system. The method also includes recording a corresponding time-varying electric potential at the location. The method also includes displaying a map of the two-dimensional coordinate system and presenting a corresponding graphical representation of the time-varying electric potential at a location in the map corresponding to the coordinate of the location. In one embodiment, the graphical representation includes rectangular bars having a length selected in response to the electric potential. In another embodiment, the graphical representation includes bars having a color selected in response to the electric potential. Summary of the Invention

[0004] Embodiments of the present invention provide a method comprising receiving an anatomical map of at least a portion of a heart. For at least one region of the anatomical map, receiving a location and a corresponding bipolar intracardiac electrogram (EGM) signal measured at the location. Identifying primary and secondary activations in the bipolar intracardiac EGM signal. Derived a surface representation of the bipolar intracardiac EGM signal over the region, including the identified primary and secondary activations. Presented the surface representation superimposed on the anatomical map.

[0005] In some embodiments, presenting the surface representation includes presenting the primary activation using a first type of visual indicator and presenting the secondary activation using a second type of visual indicator.

[0006] In some embodiments, the first type of visual indicator and the second type of visual indicator include different first and second geometric shapes. In other embodiments, the first type of visual indicator and the second type of visual indicator have different first and second colors.

[0007] In one embodiment, the first type of visual indicator and the second type of visual indicator represent a local activation time (LAT).

[0008] In another embodiment, identifying primary activations and secondary activations in a bipolar intracardiac EGM signal includes (a) selecting a noise level of the bipolar intracardiac EGM signal, (b) marking local maxima of the bipolar intracardiac EGM signal above the selected noise level as activations, and (c) for a given cardiac cycle, marking the activation with the largest absolute value as the primary activation and marking other activations as secondary activations.

[0009] According to an embodiment of the present invention, there is further provided a system comprising a memory and a processor. The memory is configured to store an anatomical map of at least a portion of a heart. The processor is configured to (i) receive, for at least one region of the anatomical map, a location and a corresponding bipolar intracardiac electrogram (EGM) signal measured at the location, (ii) identify primary activation and secondary activation in the bipolar intracardiac EGM signal, (iii) derive a surface representation of the bipolar intracardiac EGM signal over the region, including the identified primary activation and secondary activation, and (iv) present the surface representation superimposed on the anatomical map.

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

[0011] Figure 1 is a schematic diagram of a cardiac three-dimensional (3D) navigation and electrophysiological (EP) signal analysis system according to an embodiment of the present invention;

[0012] Figure 2 is a volume-rendered segment showing a point mapping visualization of bipolar intracardiac electrogram (EGM) activation patterns at two consecutive times superimposed on a portion of a cardiac chamber anatomy in accordance with an embodiment of the present invention; and

[0013] Figure 3 is a schematic diagram showing a method for Figure 2 Flowchart of the method and algorithm for point mapping visualization of bipolar intracardiac electrogram (EGM) amplitude is shown. DETAILED DESCRIPTION

[0014] Overview

[0015] To characterize cardiac electrophysiological (EP) abnormalities in a patient, a catheter-based EP mapping system can be used to generate an EP map of at least a portion of the patient's heart, such as a cardiac chamber. In a typical catheter-based EP mapping procedure, the distal end of a catheter, including sensing electrodes, is inserted into the heart to sense EP signals. As a physician operating the system moves the distal end within the heart, the EP mapping system acquires EP signals at various cardiac locations and corresponding locations at the distal end. Based on these acquired signals, a processor of the mapping system generates the desired EP map.

[0016] In some cases, a processor of an EP mapping system presents a measured EP map superimposed on cardiac anatomy visualized by, for example, a volumetric (3D) rendering of at least a portion of the heart. Such an EP superimposed rendering may be very useful in diagnosing cardiac irregularities. For example, a bipolar intracardiac electrogram (EGM) amplitude in the form of a sail or bar superimposed on the anatomical map may be used, where the height of the sail or bar gives a measure of the bipolar intracardiac EGM signal amplitude at that visualized location.

[0017] A method for ripple-mapping visualization of bipolar intracardiac EGM amplitude in the form of a translucent sail is described in U.S. patent application 16 / 228,426, entitled “Electrophysiological ripple-mapping visualization method,” filed on December 20, 2018, which is assigned to the assignee of the present patent application and the disclosure of which is incorporated herein by reference.

[0018] However, if multiple abnormal EP activations (eg, bipotentials, late potentials, fragmented signals) are present during a single cardiac cycle, clear visualization by ripple mapping (eg, in the form of sails or strips) is very difficult.

[0019] The embodiments of the present invention described below analyze each cardiac cycle to identify a primary activation and one or more secondary activations (which may or may not be present) in a bipolar intracardiac EGM signal. The activation with the largest bipolar intracardiac EGM absolute value (peak-to-peak) is assumed to be the primary activation; all one or more other activations are secondary activations. Depending on whether the activation is primary or secondary, the processor shows a first type of visual indicator or a second type of visual indicator on the 3D rendering, respectively. The visual indicator types may include, for example, small geometric shapes (e.g., dots, small squares), and these shapes may have different colors. As another example, the visual indicator may have other unique appearances, such as a flashing pattern, depending on whether a primary activation bipolar intracardiac EGM value or a secondary activation bipolar intracardiac EGM value is detected. For clarity, the physician may choose to present only one activation on the map at any given time.

[0020] By way of example, in one embodiment, the disclosed method uses a small dot that turns blue whenever a minor activation is present and turns white (or any other color selected by the physician) whenever a major activation is present.

[0021] Typically, the processor is programmed with software containing specific algorithms that enable the processor to perform each of the processor-related steps and functions listed above.

[0022] The disclosed visualization technique of superimposing bipolar intracardiac EGM activation data onto 3D cardiac anatomy using visual indicators (such as dots) having different visual forms depending on the activation type enables physicians to easily see the location of tissue exhibiting abnormal behavior (such as fragmented EP signals, double EP potentials, and late EP potentials).

[0023] Easier visualization of abnormal tissue locations in the heart that require the physician's particular attention may therefore improve the diagnostic value of catheter-based EP mapping procedures.

[0024] System Description

[0025] Figure 1 is a schematic illustration of a cardiac three-dimensional (3D) navigation and electrophysiological (EP) signal analysis system 20 according to an embodiment of the present invention. The system 20 can be configured to analyze essentially any physiological parameter or combination of such parameters. In the description herein, by way of example, it is assumed that the signals analyzed are bipolar intracardiac EGM and / or extracardiac (surface) electrocardiogram (ECG) potential-time relationships. In order to fully characterize such relationships, the processor 40 uses the bipolar intracardiac EGM signal to generate an EP map, such as a local activation time (LAT) map. A method for generating a LAT map is described in U.S. Patent 9,050,011, the disclosure of which is incorporated herein by reference in its entirety.

[0026] In the context of this disclosure, the term "anatomical map" refers to a map that models the 3D shape of at least a portion of the heart and may have one or more parameters superimposed thereon. An EP map is a special case of an anatomical map in which one or more electrophysiological parameters are superimposed. A LAT map is an example of an EP map and is therefore also considered a type of anatomical map.

[0027] Figure 1A study protocol is shown in which the system 20 uses a probe 24 to measure the actual electrical activity of a heart 34. Typically, the probe 24 comprises a catheter that is inserted into a patient 26 during a mapping procedure performed by a physician 28 using the system 20. The distal end 32 of the probe 24 is assumed to have an electrode 22. During this procedure, the patient 26 is assumed to be attached to a ground electrode 23. In addition, it is assumed that an electrode 29 is attached to the skin of the patient 26 in the region of the heart 34. In one embodiment, the probe 24 acquires local bipolar intracardiac EGMs as the probe 24 is moved over a portion of the cardiac chamber. In these cases, the position of the probe 24 is also recorded. As described above and in other uses, the measured signals are used to create a LAT map of at least a portion of the wall tissue of the heart 34 of the patient 26.

[0028] The system 20 is controlled by a system processor 40, which includes a processing unit 42 in communication with a memory 44. In some embodiments, the memory 44 included in the system processor 40 stores a LAT and / or bipolar intracardiac EGM map 62 of at least a portion of the wall tissue of the heart 34 of the patient 26. The processor 40 is typically mounted in a console 46, which includes operating controls 38, which typically include a pointing device 39, such as a mouse or trackball, that the physician 28 uses to interact with the processor.

[0029] The processor 40 (particularly the processing unit 42) runs software that includes the probe tracker module 30, the ECG module 36, and the ECG activation type visualization module 35 for visualizing bipolar intracardiac EGM activation (i.e., in the form of dots having varying colors, depending on whether the activation is primary or abnormal) on a 3D rendering of a portion of the anatomy of the heart 26, as described above and described in further detail below. The ECG module 36 is coupled to receive actual electrical signals from the electrodes 22 and 29. The module is configured to analyze the actual signals and can present the results of the analysis on the display 48 in a standard ECG format (typically a graphical representation moving over time).

[0030] The probe tracker module 30 generally tracks the position of the distal end 32 of the probe 24 within the heart of the patient 26. The tracker module may use any method known in the art for position tracking of a probe. For example, the module 30 may operate a magnetic field-based position tracking subsystem. (For simplicity, the components of such a subsystem are not shown.) Figure 1 ) 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 40 is able to measure the position of the distal end, as well as the LAT of the actual electrical signals detected at these particular positions.

[0031] Alternatively or in addition, tracker module 30 can track 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 may provide both bipolar intracardiac EGM and position tracking signals.) The system uses both magnetic field position tracking and impedance measurements for position tracking.

[0032] The results of the operations and visualizations performed by the processor 40 are presented to the physician 28 on a display 48, which typically presents the physician with a graphical user interface, a visual representation of the bipolar intracardiac EGM signals sensed by the electrodes 22, and / or an image or map of the heart 34 being studied. In one embodiment, the EP activation type visualization module 35 presents the physician with a LAT map superimposed with bipolar intracardiac EGM activation represented as dots of various colors depending on the type of activation (e.g., primary or abnormal).

[0033] The processor 40 typically comprises a general purpose computer having software programmed to perform the functions described herein. Specifically, the processor 40 executes the software disclosed herein including Figure 3 The software executed by the processor 40 may be downloaded to the processor 40 in electronic form over a network, or, alternatively or in addition, may be provided and / or stored on a non-transitory tangible medium such as magnetic, optical or electronic memory.

[0034] Visually distinguishing primary from secondary activation on electrophysiological maps

[0035] Figure 2 is a volume-rendered segment showing a point mapping visualization of bipolar intracardiac electrogram (EGM) activation patterns at two consecutive times superimposed on a portion of a cardiac chamber anatomy 50, in accordance with an embodiment of the present invention.

[0036] Figure 2 Two screen captures of a surface representation of a bipolar intracardiac EGM signal (according to the type of bipolar intracardiac EGM activation superimposed on an anatomical map) taken from a display video (e.g., a video displayed on the display 48 of the system 20) at times T0 and T0+ΔT are shown. Figure 2 As shown, the captured main and anomalous patterns vary within a time step ΔT, which is typically on the order of a fraction of a second.

[0037] exist Figure 2In FIG, the analyzed activations visualized by points 60 and 66 are superimposed by processor 40 on a grayscale anatomical map, where the colors of points 60 and 66 give an indication of the type of bipolar intracardiac EGM activation at the circled locations. Figure 2 In FIG, white dots 60 indicate primary activations, while black dots 66 indicate secondary abnormal activations.

[0038] In some embodiments, to visualize the bipolar intracardiac EGM signal as disclosed, the processor 40 analyzes the bipolar intracardiac EGM signal by applying the following steps:

[0039] (i) selecting the noise level of the bipolar intracardiac EGM signal after the bipolar intracardiac EGM signal is pre-filtered and a stable baseline is acquired,

[0040] (ii) marking a local maximum in the absolute value of the bipolar intracardiac EGM signal as active whenever the peak is above a chosen noise level,

[0041] (iii) at each heartbeat, the activation with the largest absolute value of the bipolar intracardiac EGM is marked as the primary activation at a given visualization window scale, and the other activations are marked as secondary activations,

[0042] (iv) placing an initial visual indicator (e.g., a black dot) on the cardiac map and changing the initial visual indicator to a first visual indicator (e.g., a white dot) for a location showing a primary activation, or to a second visual indicator (e.g., a blue dot) for a location showing a secondary activation (or to any color or shape selected by the physician).

[0043] In some embodiments, the noise level can be dynamically set by the processor 40 based on a specific percentile of the signal (e.g., the noise level can be set to the 10th percentile of the absolute values ​​of the bipolar intracardiac EGM in a sliding window of the last 10 seconds of the bipolar intracardiac EGM signal). The noise level can be dynamically set based on the standard deviation of the absolute values ​​of the bipolar intracardiac EGM signal over the sliding window multiplied by a constant (e.g., twice the standard deviation over the sliding window of the last 10 seconds). At least up to a specific percentage of activations that are primary activations (e.g., 90% of the primary activations) can be considered primary activations. A secondary activation can be considered primary (i.e., a feature in the waveform of a primary activation) if the primary and secondary activations occur at very similar times, i.e., coincide within a given number of milliseconds (e.g., 25 milliseconds).

[0044] In one embodiment, instead of the absolute value of the bipolar intracardiac EGM signal, the processor may examine the first derivative of the signal. The processor then looks for the maximum absolute value of the derivative to distinguish between primary and secondary activations.

[0045] In some embodiments, if a primary or secondary activation coincides with a QRS complex of a bipolar intracardiac EGM waveform, it may be colored differently. The definition of "coincident with a QRS" may be within a pre-specified range in milliseconds from the corresponding R peak. Alternatively, a QRS complex may be detected and the entire QRS time interval may be considered. Optionally, the user may specify some range in milliseconds around the QRS complex. For example, the processor may color an activation that coincides with an interval starting five milliseconds before the QRS until five milliseconds after the QRS complex as a yellow dot.

[0046] In one embodiment, a primary activation or a secondary activation may be colored differently if the primary activation or secondary activation coincides with a pacing peak. The definition of "coincident with a pacing peak" may be given as a primary activation or a secondary activation occurring within a given number of milliseconds of the timing of the pacing peak.

[0047] Figure 2 The exemplary point mapping visualization shown is chosen solely for conceptual clarity. Various additional visualization tools may be applied, such as using another shape (eg, a diamond) to present activation, using a magnifying glass effect to view points 60 and 66 in detail, and so forth.

[0048] Figure 3 is a schematic diagram showing a method for Figure 2 Flowchart of a method for point mapping visualization of bipolar intracardiac electrogram (EGM) activity types is shown. According to the presented embodiment, the algorithm performs the following process, which begins at a bipolar intracardiac EGM activation type assignment step 70, where the processor 40 assigns the bipolar intracardiac EGM activation types analyzed using steps (i)-(iv) above to corresponding locations on an anatomical map of the cardiac chamber (such as, for example, the LAT mapping surface of the cardiac chamber 50).

[0049] Next, at a shape and color selection step 72, the processor 40 selects a geometric shape and a shape color according to the type of activation (e.g., white for primary activation and blue for secondary activation). Next, at an overlay bipolar intracardiac EGM activation data points step 74, the processor 40 overlays the color-coded shapes on the anatomical map according to the type of activation at each analysis location. Finally, at a map display step 76, the processor 40 displays the resulting visualization (e.g., including overlay points colored according to activation type (e.g., blue for secondary activation)). Figure 2 The LAT map of points 60 and 66) is presented to the physician 28 on the display 48.

[0050] Figure 3The exemplary flow chart shown in FIG is selected solely for conceptual clarity. This embodiment also includes additional steps of the algorithm. The example includes additional visualizations, such as a conductive arrow between points 60 and 66. In order to provide a more simplified flow chart, such additional steps are intentionally omitted from the disclosure herein.

[0051] Although the embodiments described herein primarily relate to cardiac mapping, the methods and systems described herein may also be used in other applications, such as EP mapping of brain tissue.

[0052] It should be understood that the above embodiments are cited by way of example, and the present invention is not limited to what is specifically shown and described above. On the contrary, the scope of the present invention includes combinations and subcombinations 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. The documents incorporated by reference into this patent application are considered to be an integral part of this application, except that if any term defined in these incorporated documents conflicts with a definition explicitly or implicitly given in this specification, only the definition in this specification should be considered.

Claims

1. A method for visually distinguishing primary activation from secondary activation on an electrophysiological map, comprising: receiving an anatomical map of at least a portion of the heart; for at least one region of the anatomical map, receiving a location and a corresponding bipolar intracardiac electrogram (EGM) signal measured at the location; identifying primary activation and secondary activation in the bipolar intracardiac EGM signal; deriving a surface representation of the bipolar intracardiac EGM signal over the region, including the identified primary and secondary activations; and presenting the surface representation superimposed on the anatomical map, Wherein identifying the primary activation and the secondary activation in the bipolar intracardiac EGM signal among the bipolar intracardiac EGM signal comprises: selecting a noise level for the bipolar intracardiac EGM signal; marking local maxima of the bipolar intracardiac EGM signal above a selected noise level as activation; and For a given cardiac cycle, the activation with the largest absolute value is labeled as the primary activation, and the other activations are labeled as secondary activations. 2 . The method of claim 1 , wherein presenting the surface representation comprises presenting the primary activation using a first type of visual indicator and presenting the secondary activation using a second type of visual indicator. 3 . The method of claim 2 , wherein the visual indicator of the first type and the visual indicator of the second type comprise different first and second geometric shapes. The method of claim 2 , wherein the visual indicator of the first type and the visual indicator of the second type have different first and second colors.

5. A system for visually distinguishing primary activation from secondary activation on an electrophysiological map, comprising: a memory configured to store an anatomical map of at least a portion of the heart; as well as a processor configured to: for at least one region of the anatomical map, receiving a location and a corresponding bipolar intracardiac electrogram (EGM) signal measured at the location; identifying primary activation and secondary activation in the bipolar intracardiac EGM signal; deriving a surface representation of the bipolar intracardiac EGM signal over the region, including the identified primary and secondary activations; and presenting the surface representation superimposed on the anatomical map, wherein the processor is configured to identify, among the bipolar intracardiac EGM signals, the primary activation and the secondary activation in the bipolar intracardiac EGM signal by: selecting a noise level for the bipolar intracardiac EGM signal; marking local maxima of the bipolar intracardiac EGM signal above a selected noise level as activation; as well as For a given cardiac cycle, the activation with the largest absolute value is labeled as the primary activation, and the other activations are labeled as secondary activations. 6 . The system of claim 5 , wherein the processor is configured to present the surface representation by presenting the primary activation using a first type of visual indicator and presenting the secondary activation using a second type of visual indicator. 7 . The system of claim 6 , wherein the visual indicator type of the first type and the visual indicator type of the second type comprise different first and second geometric shapes.

8. The system of claim 6, wherein the visual indicator type of the first type and the visual indicator type of the second type have different first and second colors.

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