Local ECG annotation visualization

Abstract

The subject matter of the invention is "local ECG annotation visualization". Methods and systems for electrophysiological measurements involve obtaining a signal indicative of electrical activity of the heart by using electrodes in contact with body tissue of a living patient. The signals are then processed to identify local activation times at the electrodes. The identified local activation time is displayed on the display screen as a trajectory representing the change of these signals over time. The brightness of a particular trajectory segment within a specified time window may be increased relative to segments outside the specified time window encompassing the identified local activation time. The method provides flexibility of signal acquisition, allowing the use of intracardiac electrogram signals acquired within the heart or electrocardiogram signals acquired from the body surface. The method enhances visibility and enables efficient analysis of cardiac activity trajectories for diagnostic and monitoring purposes.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This patent application claims the benefit of U.S. Provisional Patent Application No. 63 / 448,415, filed February 27, 2023, the disclosure of which is incorporated herein by reference. Technical Field

[0003] The present disclosure relates to electrophysiological measurements, and in particular to displaying electrophysiological signals. Background Art

[0004] Electrophysiological measurements from human tissue can provide important diagnostic information about the state of the tissue. For example, signals indicating cardiac electrical activity in the human heart are typically recorded by measuring electrodes and analyzed to measure the local activation time (LAT) of the cardiac tissue at each electrode. The signal trace can be visually presented to the clinician as an electrogram. Annotation points representing LAT can be automatically marked by superimposing an icon on the visual presentation of the corresponding electrogram. Clinicians can use LAT and other characteristics of the electrogram to assess the state of the cardiac tissue.

[0005] The present disclosure will be more fully understood through the following detailed description of examples of the present disclosure in conjunction with the accompanying drawings, in which: Summary of the Invention

[0006] According to embodiments disclosed herein, methods, apparatus, and computer-readable media for electrophysiological measurements include acquiring signals indicative of cardiac electrical activity from electrodes in contact with bodily tissue of a living patient. These acquired signals are then processed to identify local activation times at one or more of these electrodes. Another aspect may involve displaying a trajectory representing the signal over time on a display screen. In some aspects, within a specified duration window encompassing the identified local activation times, the brightness of segments of the trajectory may be increased relative to portions of the trajectory outside the time window.

[0007] Additional aspects of the method include acquiring the signal by receiving an intracardiac electrogram signal acquired within the patient's heart or an electrocardiogram signal acquired from the patient's body surface. In certain aspects, the specified duration of the time window is in the range of 10 ms to 100 ms. Furthermore, in one aspect, the system and method can ensure that the displayed trace is presented without overlaying an icon representing the local activation time. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 An exemplary catheter-based electrophysiological mapping and ablation system according to examples of the present disclosure is shown;

[0009] Figure 2is a diagram schematically illustrating identification of annotation points in an electrophysiological signal according to an example of the present disclosure; and

[0010] Figure 3 is a schematic representation of a display including a highlighted segment of a recorded electrogram according to an example of the present disclosure. DETAILED DESCRIPTION

[0011] Overview

[0012] Measurement of local activation time (LAT) in cardiac tissue is useful, for example, in estimating electrical conduction velocity (CV) in cardiac tissue and in identifying arrhythmias and other pathologies. Local activation times can be automatically identified using digital signal processing techniques and can be graphically indicated by marking annotation points on the electrogram signal trace. Various algorithms can be used to select annotation points in unipolar, bipolar, or multipolar electrogram signals. For example, the annotation points can indicate the time points at which the time derivative of the signal reaches its lowest negative value.

[0013] In many systems, the signals received by the electrodes are presented on a display screen as multiple parallel tracks that change over time. Each annotation point is marked on the corresponding signal track by an icon (such as a large dot). These icons are useful in attracting the clinician's attention to the LAT differences between electrodes, but they tend to obscure the form and quality (morphology) of the signal around the annotation point. Therefore, the icons may make it difficult for the clinician to view and evaluate clinically meaningful details in the electrogram morphology.

[0014] There is a need for an electrophysiological signal processing and display mode in which annotations can be automatically identified and visually presented to the clinician without compromising the visibility of the morphology of the signal trajectory. The present disclosure addresses this need by displaying the signal so that segments of the trajectory within a time window of a specified duration containing the corresponding annotation point are displayed with increased brightness relative to the portions of the trajectory outside the time window. Thus, the signal segments within the time window can be displayed without overlaying the icons marking the annotation points on the trajectory. The brightened trajectory highlights the local activation times without cluttering the signal segments around the corresponding annotation point, thereby drawing the clinician's attention to these segments while enhancing the clinician's understanding of the signal morphology.

[0015] The examples described below relate particularly to the processing and display of intracardiac electrograms. Alternatively, the principles of the present disclosure may be applied to other electrophysiological signals, and in particular signals generated by the heart, such as electrocardiogram signals acquired from the body surface.

[0016] System Description

[0017] Figure 1 An exemplary catheter-based electrophysiological mapping and ablation system 20 according to an example of the present disclosure is shown. The system 20 may include a plurality of catheters that are inserted percutaneously through the vascular system of a patient 23 into a chamber or vascular structure of a heart 24 by a physician 22. Typically, a delivery sheath (not shown) is inserted into the left atrium or the right atrium near a desired location in the heart 24. One or more catheters 26 are then inserted through the delivery sheath to reach the desired location in the heart 24. The plurality of catheters may include catheters dedicated to sensing intracardiac electrogram (IEGM) signals, catheters dedicated to ablation, and / or catheters dedicated to both sensing and ablation. In the illustrated example, a distal portion of the catheter 26 includes a basket assembly 28. The physician 22 can manipulate the catheter 26 to place the basket assembly 28 in contact with the heart wall for sensing a target site in the heart 24 and / or for ablating tissue at the target site.

[0018] Catheter 26 is an exemplary catheter that includes a plurality of electrodes 30 distributed over a plurality of spines 32 in a basket assembly 28 and configured to sense IEGM signals and / or ablate myocardial tissue. Catheter 26 also includes one or more position sensors 34 embedded in a distal portion of the catheter for tracking the position and orientation of basket assembly 28, as further described below. For example, position sensor 34 may include a magnetic position sensor including three magnetic coils for sensing three-dimensional (3D) position and orientation.

[0019] The magnetic position sensor 34 can operate in conjunction with a positioning mat 36 including a plurality of magnetic coils 38 configured to generate a magnetic field in a predefined working volume containing the heart 24. The position of the basket assembly 28 of the catheter 26 can be tracked based on the magnetic field generated by the positioning mat 36 and sensed by the magnetic position sensor 34 (which can include three orthogonal coils). Details of magnetic position sensing technology that can be used for this purpose are described, for example, in U.S. Patents 5,5391,199, 5,443,489, 5,558,091, 6,172,499, 6,239,724, 6,332,089, 6,484,118, 6,618,612, 6,690,963, 6,788,967, and 6,892,091.

[0020] The plurality of catheters may also include a reference catheter 39, which is percutaneously inserted by physician 22 through the vascular system of patient 23. Physician 23 brings an electrode at the distal end (not shown) of reference catheter 39 into contact with the coronary sinus of heart 24 of patient 23. Reference catheter 39 typically remains in place for the duration of the procedure and provides a reference timing signal to which LAT measurements made by catheter 26 are referenced.

[0021] The system 20 optionally includes one or more electrode patches 40 that contact the skin of the patient 23 to establish a position reference for impedance-based tracking of the positioning pad 36 and the electrodes 30. For impedance-based tracking, current is directed to the electrodes 30 and sensed at the electrode patches 40, so that the position of each electrode 30 can be triangulated via the electrode patches 40. Details of such impedance-based position tracking techniques are described in U.S. Patents 7,536,218, 7,756,576, 7,848,787, 7,869,865, and 8,456,182.

[0022] Recorder 42 records and displays electrograms 44 captured by surface ECG electrodes 46 and intracardiac electrograms (IEGMs) captured by electrodes 30 of catheter 26. Recorder 42 may include pacing capabilities for pacing the cardiac rhythm and / or may be electrically connected to a separate pacemaker.

[0023] The system 20 may include an ablation energy generator 48 for providing ablation energy to one or more of the electrodes 30. The energy generated by the ablation energy generator 48 may include, but is not limited to, radio frequency (RF) energy or pulsed field ablation (PFA) energy (including monopolar or bipolar high voltage DC pulses that may be used to achieve irreversible electroporation (IRE)), or a combination thereof.

[0024] A patient interface unit (PIU) 50 includes an interface for electrical communication between the catheter 26, other electrophysiology equipment, a power source, and a workstation 52 for controlling the operation of the system 20. The electrophysiology equipment in the system 20 may include, for example, multiple catheters 26 (including catheters with distal assemblies and electrode arrays other than basket-style catheters), positioning pads 36, surface ECG electrodes 46, electrode patches 40, an ablation energy generator 48, and a recorder 42. Optionally, the PIU 50 also includes processing capabilities for enabling real-time calculation of the position of the catheter and for processing ECG signals.

[0025] The workstation 52 includes a memory and a processor having stored therein appropriate operating software and user interface capabilities. The workstation 52 may provide a plurality of functions, which may optionally include: (1) three-dimensional (3D) modeling of the endocardial anatomy and rendering of the model or anatomical map 54 for display on a display screen 56; (2) displaying on the display screen 56 an activation sequence (or other data) compiled from the recorded electrograms 44 as representative visual markers or images superimposed on the rendered anatomical map 54; (3) displaying the real-time position and orientation of one or more catheters within the heart 24; and (4) displaying on the display screen 56 a region of interest (such as where ablation energy has been applied). A commercial product embodying elements of the system 20 is 3 system, which was purchased from Biosense Webster, Inc., 31A Technology Drive, Irvine, CA 92618.

[0026] In an example of the present disclosure, the workstation 52 processes the electrogram signal output by the catheter 26 to find corresponding annotation points corresponding to the local activation time, and highlights the annotation points on the display screen 56 by increasing the brightness of the trace within the time window containing the local activation time. Figure 3 This display mode is further described.

[0027] Display of local activation time

[0028] Figure 2 1 is a diagram schematically illustrating identification of annotation points 100 in an exemplary electrophysiological signal 102 according to an example of the present disclosure. View 104 shows the electrophysiological signal 102 within a window 106. For clarity, view 104 is stretched along the time axis (horizontal axis) to view 108. Workstation 52 ( Figure 1 ) calculates the position of the annotation point 100 on the signal 102 as the position between the positive peak 110 and the negative peak 112 where the slope 114 (time derivative) of the signal reaches an extreme negative value. This position corresponds to the inflection point of the electrophysiological signal 102.

[0029] In more complex electrophysiological signals, the processor may use alternative algorithms to calculate the positions of their corresponding annotation points.

[0030] Figure 3 is a display screen 56 ( Figure 1), showing a highlighted segment of a recorded electrogram 44. The electrogram 44 is represented by a corresponding trace on the display screen 56 and is labeled along the left edge of the display by alphanumeric labels A1-A8, B1-B8, C1-C8, D1-D8, E1-E8, and F1-F8. A window of interest (WOI) 200 encompassing the local activation times of the electrogram 44 is marked on the electrogram 44 by two vertical lines 202 and 204. The WOI 200 can be selected by an operator of the electrophysiology system (such as the physician 22), or it can be automatically selected by the system.

[0031] The processor of workstation 52 has calculated the positions of the corresponding annotation points corresponding to the local activation times in electrograms A1-A8, B1-B8, and D1-D8. The processor increases the brightness of the electrogram segments within the time window relative to the portions of the trace outside the time window of the specified duration that contains the identified local activation times. As an example, this type of bright segment is shown in box 206 around electrogram A3, while the remainder of the trace within WOI 200 is dimmed. Portions of the trace outside WOI 200 can also be dimmed, or they can be displayed at full brightness. Some of the other electrograms show more complex signal forms, in which the positions of the corresponding annotation points have been calculated by the processor.

[0032] The temporal width of each bright segment around the annotation point is typically between about 10ms and 100ms. Figure 3 In the example shown, the brightened time window in each track has a duration of 15 ms. Even without overlaying the icons representing the local activation times on the tracks, the LAT in each track and the changes in LAT between tracks can be easily visualized.

[0033] It should be understood that the above examples are cited by way of example only, and the present disclosure is not limited to what has been specifically shown and described above. On the contrary, the scope of the present disclosure 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.

Claims

1. A method for electrophysiological measurement, comprising: acquiring signals indicative of cardiac electrical activity from electrodes contacting tissue of the living patient's body; processing the signal to identify local activation times at one or more of the electrodes; as well as A trace representing the signal over time is displayed on a display screen while increasing the brightness of segments of the trace within the time window relative to portions of the trace outside the time window of a specified duration containing the identified local activation times.

2. The method according to claim 1, wherein Acquiring the signal includes receiving an intracardiac electrogram signal acquired within the heart of the living patient.

3. The method according to claim 1, wherein Acquiring the signal includes receiving an electrocardiogram signal acquired from a body surface of the living patient.

4. The method according to claim 1, wherein The specified duration is between 10 ms and 100 ms.

5. The method according to claim 1, wherein Displaying the trajectory includes presenting the trajectory on the display screen without covering an icon representing the local activation time on the trajectory.

6. A medical device comprising: Display screen; and A processor configured to: acquiring signals indicative of cardiac electrical activity from electrodes contacting tissue of the living patient's body; processing the signal to identify local activation times at one or more of the electrodes; as well as A trace representing the signal over time is displayed on a display screen while increasing the brightness of segments of the trace within the time window relative to portions of the trace outside the time window of a specified duration containing the identified local activation times.

7. The device according to claim 6, wherein The signal includes an intracardiac electrogram signal acquired within the heart of the living patient.

8. The device according to claim 6, wherein The signal includes an electrocardiogram signal collected from the body surface of the living patient.

9. The device according to claim 6, wherein The specified duration is between 10 ms and 100 ms.

10. The device according to claim 6, wherein The processor is configured to present the trajectory on the display screen without overlaying an icon on the trajectory representing the local activation time.

11. A computer-readable medium comprising instructions for electrophysiological measurement, the instructions, when executed by a processor, causing the processor to perform the following steps: acquiring signals indicative of cardiac electrical activity from electrodes contacting tissue of the living patient's body; processing the signal to identify local activation times at one or more of the electrodes; and A trace representing the signal over time is displayed on a display screen while increasing the brightness of segments of the trace within the time window relative to portions of the trace outside the time window of a specified duration containing the identified local activation times.

12. The computer-readable medium of claim 11, wherein: The instructions for acquiring the signals include instructions for receiving intracardiac electrogram signals acquired within the heart of the living patient.

13. The computer-readable medium of claim 11, wherein: The instructions for acquiring the signal include instructions for receiving an electrocardiogram signal acquired from a body surface of the living patient.

14. The computer-readable medium of claim 11, wherein: The instruction for the specified duration is set in a range between 10 ms and 100 ms.

15. The computer-readable medium of claim 11, wherein: The instructions for displaying the trajectory include instructions for presenting the trajectory on the display screen without overlaying an icon on the trajectory representing the local activation time.

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