Identifying and indicating cardiac regions exhibiting gradually slowed activation (PSA)

Abstract

A method includes receiving a cardiac signal sensed by an electrode at a location in a heart of a patient, the cardiac signal including signal components induced by respective activations. Signal components in a cardiac signal are found and annotated. A respective time difference between the annotation and the corresponding activation is calculated. Based on the time difference, one or more cardiac tissue locations are identified that exhibit gradually slowed activation (PSA). An EP map of at least a portion of the heart is presented to the user, including providing a graphical indication of one or more tissue locations exhibiting the PSA.

Description

Technical Field

[0001] The present disclosure relates generally to electrophysiological (EP) signals, and in particular to the evaluation of electrical propagation in the heart. Background Art

[0002] The estimation of electrophysiological signals to determine local activation time (LAT) has been previously proposed in the patent literature. For example, U.S. Patent 5,954,661 describes cardiac tissue that is characterized by the use of pacing without inducing ventricular tachycardia (VT). By characterizing the tissue, the patient's risk of developing ventricular tachycardia can be determined, and slow conduction areas in the patient's heart can be identified. The characterization involves applying pacing signals with different pacing cycle intervals to the chambers of the patient's heart to pace the patient's heart. The response signal generated by the paced heart is received and used as a basis for characterizing the patient's cardiac tissue.

[0003] The present disclosure will be more fully understood through the following detailed description of the embodiments of the present disclosure in conjunction with the accompanying drawings, in which: BRIEF DESCRIPTION OF THE DRAWINGS

[0004] Figure 1 is a schematic illustration of a catheter-based electrophysiological (EP) mapping and ablation system according to one example of the present disclosure;

[0005] Figure 2 shows the use of an example according to the present invention Figure 1 Example of a bipolar electrogram acquired by a system with a gradually decreasing activation (PSA) potential annotated on the bipolar signal;

[0006] Figure 3 is a flow chart schematically illustrating a method and algorithm for finding the location of cardiac chamber tissue exhibiting PSA according to one example of the present disclosure; and

[0007] Figure 4 is a schematic graphical volume rendering of an EP map graphically indicating the found left atrial location exhibiting PSA according to one example of the present disclosure. DETAILED DESCRIPTION

[0008] Overview

[0009] To characterize cardiac chamber arrhythmias (eg, reentrant arrhythmias), physicians may use a multi-electrode mapping catheter to perform electrophysiological (EP) mapping of suspected tissue pathways and circuits within the chamber.

[0010] In EP mapping, EP properties of tissue, such as local activation time (LAT), are measured under sinus rhythm or rapid pacing and then correlated with the arrhythmogenicity of the local tissue. Dedicated pacing catheters can be used to pace the heart chambers, while EP mapping catheters acquire bipolar electrograms from various tissue locations. A processor can run an algorithm that identifies tissue with unhealthy electrophysiological properties, such as locations exhibiting low bipolar potentials and / or abnormal conduction times (relative to the timing of the pacing signal).

[0011] Once arrhythmogenic tissue is identified, specialized ablation catheters can be used to eliminate the potential for arrhythmia (eg, by ablating and blocking stray conduction pathways that lead to reentrant circuits).

[0012] However, in practice, it may be difficult to identify unique EP patterns (eg, temporal patterns) of arrhythmogenic sites or pathways due to, for example, inherent variability and signal noise.

[0013] The authors of the present disclosure have noted that during pacing, activation times measured at greater distances from the pacing site sometimes gradually increase over the pacing cycle. This gradual increase, hereinafter referred to as progressively slower activation (PSA), often indicates the presence of arrhythmogenic tissue (arrhythmogenicity may be localized or may manifest as an arrhythmogenic tissue pathway between the pacing site and the measurement site). The presence of abnormal tissue may be associated with the arrhythmogenicity of the tissue, which may be present as part of a reentrant arrhythmia.

[0014] Examples of the present disclosure described below provide PSA mapping methods and systems that automatically identify PSA activity without triggering actual arrhythmias. The methods and systems use visual, auditory, and / or tactile means to analyze, display, and notify a physician of PSA activity. In one example, a processor displays PSA activity by superimposing a graphical indication of PSA location clusters on a cardiac EP map.

[0015] The disclosed method of automatic PSA mapping includes receiving a pacing signal applied to the patient's heart. The pacing signal includes a series of regular pacing stimuli having the same cycle length (CL) between them, which is shorter than the naturally occurring sinus rhythm. (CL can range between close to normal sinus CL and much shorter than CL). In the context of this specification, the wording "regular pacing stimuli" covers pulses that are equidistant within a predefined variation range. Typically, the predefined variation is limited to approximately 1% of the specified equidistant intervals, although larger deviations, such as 5%, can be tolerated in some cases. Pacing is typically applied by a dedicated pacing catheter that contacts the heart tissue at a fixed position.

[0016] A response signal of a propagating cardiac activation wave is received, which is sensed by electrodes of a multi-electrode mapping catheter in contact with a tissue location in the heart. For each intracardiac bipolar channel of the multi-electrode mapping catheter, the processor finds and annotates activation after each pacing. The time difference (e.g., LAT value) between each evoked potential and a fixed timing reference in the pacing pulse (e.g., the timing of the previous pacing spike) is calculated. This measurement of bipolar potential LAT is performed in multiple locations in the cardiac chambers. Tissue locations that exhibit an increase in the time difference for at least two consecutive beats (i.e., within three consecutive pacing cycles) are identified as possible PSA locations.

[0017] The processor constructs an EP map of at least a portion of the heart and presents it to the user, graphically indicating where PSA activity is found. Optionally, a boundary around a cluster of PSA sites is indicated. The physician can choose to ablate a location within the indicated boundary or a specific PSA site.

[0018] The spatial stability of the catheter may also be monitored to ensure that there is no significant catheter movement that could cause variations in LAT between pacing cycles.

[0019] Finally, naturally occurring sinus rhythm activation can also be used (although less accurately) to identify PSA without pacing.

[0020] Therefore, in one example, a system is provided that includes an interface and a processor. The interface receives a cardiac signal sensed by electrodes at locations in a patient's heart, the cardiac signal including a signal component induced by a corresponding activation. The processor analyzes the induced signal component to locate and annotate the signal component in the cardiac signal. The processor then calculates a corresponding time difference between the annotation and the corresponding activation. Based on the time difference, the processor identifies one or more cardiac tissue locations exhibiting PSA. The processor presents an EP map of at least a portion of the heart to a user, including providing a graphical indication of the one or more tissue locations exhibiting PSA.

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

[0022] The disclosed PSA mapping technology introduces a new and unique EP mapping tool to the arsenal of existing EP mapping tools, which may increase the sensitivity and specificity of EP mapping.

[0023] System Description

[0024] Figure 1 is a schematic illustration of a catheter-based electrophysiological (EP) mapping and ablation system 10 according to one example of the present disclosure.

[0025] The system 10 includes a plurality of catheters that are inserted percutaneously through the patient's vascular system into a chamber or vascular structure of the heart 12 by a physician 24. Typically, a delivery sheath catheter is inserted into a cardiac chamber (such as the left atrium or right atrium) near a desired location in the heart 12. Multiple catheters can then be inserted into the delivery sheath catheter to reach the desired location. The multiple catheters may include catheters dedicated to pacing, catheters for sensing intracardiac electrogram signals, and catheters dedicated to ablation and / or catheters dedicated to both EP mapping and ablation. An example catheter 14 configured for sensing bipolar electrograms is illustrated herein. The physician 24 brings the distal tip 28 of the catheter 14 (hereinafter also referred to as the "distal tip assembly 28") into contact with the heart wall for sensing a target site in the heart 12. For ablation, the physician 24 similarly brings the distal tip of the ablation catheter to the target site for ablation.

[0026] The catheter 14 is an exemplary catheter that includes one (and preferably multiple) electrodes 26, optionally distributed over a plurality of splines 22 at a distal tip 28, and configured to sense IEGM signals. The catheter 14 may further include a position sensor 29 embedded in or near the distal tip 28 for tracking the position and orientation of the distal tip 28. Optionally and preferably, the position sensor 29 is a magnetic-based position sensor that includes three magnetic coils for sensing three-dimensional (3D) position and orientation.

[0027] The magnetic-based position sensor 29 can operate in conjunction with the positioning mat 25, which includes a plurality of magnetic coils 32 configured to generate a magnetic field in a predefined working space. The real-time position of the distal tip 28 of the catheter 14 can be tracked based on the magnetic field generated by the positioning mat 25 and sensed by the magnetic-based position sensor 29. Details of magnetic-based position sensing technology are described in U.S. Patents Nos. 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.

[0028] System 10 includes one or more electrode patches 38 positioned in contact with the skin of patient 23 to establish a position reference for impedance-based tracking of positioning pad 25 and electrodes 26. For impedance-based tracking, current is directed toward electrodes 26 and sensed at electrode skin patches 38, so that the position of each electrode can be triangulated via electrode patches 38. Details of impedance-based position tracking technology are described in U.S. Patents Nos. 7,536,218, 7,756,576, 7,848,787, 7,869,865, and 8,456,182.

[0029] Recorder 11 displays electrograms 21 captured using surface ECG electrodes 18 and intracardiac electrograms captured using electrodes 26 of catheter 14. Recorder 11 may include pacing capabilities for pacing the cardiac rhythm and / or may be electrically connected to a separate pacemaker.

[0030] The system 10 may include an ablation energy generator 50 adapted to conduct ablation energy to one or more electrodes at the distal tip of a catheter configured for ablation. The energy generated by the ablation energy generator 50 may include, but is not limited to, radiofrequency (RF) energy or pulsed field ablation (PFA) energy (including monopolar or bipolar high voltage DC pulses that can be used to achieve irreversible electroporation (IRE)), or a combination thereof.

[0031] The patient interface unit (PIU) 30 is an interface configured to establish electrical communication between catheters, electrophysiology equipment, a power source, and a workstation 55 for controlling the operation of the system 10. The electrophysiology equipment of the system 10 may include, for example, a plurality of catheters, a positioning pad 25, surface ECG electrodes 18, electrode patches 38, an ablation energy generator 50, and a recorder 11. Optionally and preferably, the PIU 30 further includes processing capabilities for enabling real-time calculation of catheter position and for performing ECG calculations.

[0032] The workstation 55 includes a memory 57, a processor 56 unit with memory or storage loaded with appropriate operating software, and user interface capabilities. The workstation 55 can provide a variety of functions, optionally including: (1) three-dimensional (3D) modeling of the endocardial anatomy and rendering the model or anatomical map 20 for display on the display device 27; (2) displaying on the display device 27 the activation sequence (or other data) compiled from the recorded electrograms 21 as representative visual markers or images superimposed on the rendered anatomical map 20; (3) displaying the real-time position and orientation of multiple catheters within the heart chamber; and (5) displaying on the display device 27 a site of interest (such as where ablation energy has been applied). A commercial product embodying elements of the system 10 can be CARTO TMThe 3 system was purchased from Biosense Webster, Inc., 31A Technology Drive, Irvine, CA 92618.

[0033] In some examples, processor 56 typically comprises a general-purpose computer that is programmed in software to perform the functions described herein. The software may be downloaded to the computer in electronic form over a network, for example, or it may alternatively or additionally be provided and / or stored on a non-transitory tangible medium such as magnetic, optical, or electronic memory.

[0034] This particular configuration of system 10 is shown by way of example in order to illustrate certain problems solved by the examples of the present disclosure and to demonstrate the application of these examples in enhancing the performance of such systems. However, the examples of the present disclosure are by no means limited to this particular class of example systems, and the principles described herein may be similarly applied to other classes of medical systems. For example, other types of multi-electrode catheters, such as OCTARAY TM catheter or basket catheter.

[0035] Identify locations expressing PSA

[0036] Figure 2 shows the use of an example according to the present disclosure Figure 1 10 system 10, wherein the PSA potential is annotated (204) on the bipolar signal. The dashed line 202 indicates the timing of the equidistant (203) pacing stimulation (eg, the aforementioned corresponding activation).

[0037] As shown, the processor's annotation 204 of the evoked signal component appears as five consecutive PSA time differences 206 of 387 milliseconds, 396 milliseconds, 410 milliseconds, 418 milliseconds, and 424 milliseconds over five pacing cycles. The processor then calculates the corresponding sequence of changes in the time differences. Figure 2 In the electrogram in FIG, this corresponds to a sequence of four increments caused by PSA, with values ​​of +9 milliseconds, +14 milliseconds, +8 milliseconds, and +6 milliseconds. As the authors found, this consistent PSA behavior is highly predictive, i.e., the location where the electrogram 200 was acquired is an arrhythmogenic region.

[0038] Figure 2 This is given by way of example and the method can be applied to different types of electrograms. Specifically, the method can annotate PSA on unipolar or multipolar electrograms.

[0039] Methods for identifying and indicating areas expressing PSA

[0040] Figure 3is a flow chart schematically illustrating a method and algorithm for locating cardiac chamber tissue exhibiting PSA according to one example of the present disclosure. According to the presented example, at a pacing step 302, the algorithm execution begins with the system 10 applying a pacing signal in the form of a train of equidistant (203) pacing pulses.

[0041] At an EP data reception step 304 , processor 56 receives pacing signals from catheter 14 , bipolar signals (eg, waveforms), and corresponding ECG signals from body surface (BS) electrodes.

[0042] Next, the processor 56 annotates 204 the evoked potentials at an EP response extraction step 306. The processor may use an annotation algorithm produced by Biosense Webster to identify late potentials.

[0043] At a time difference calculation step 308 , using the pacing stimulus timing 202 and the annotations 204 made by the processor, the processor 56 calculates the time difference 206 .

[0044] At the PSA analysis step 310 , the processor 56 calculates the corresponding variation sequence of the time difference 206 , such as Figure 2

[0014] As done in , criteria are used to identify chamber locations exhibiting PSA. One example of a criterion is that a tissue location exhibits an increasing time difference of at least two consecutive beats (i.e., within three consecutive pacing cycles) to be identified as a possible PSA location.

[0045] Finally, at a PSA location overlay step 312, processor 28 indicates the PSA location on the EP map as follows Figure 4 shown.

[0046] Figure 3 The example flow chart shown in FIGURE 1 is selected solely for conceptual clarity. This example may also include additional steps in the algorithm, such as simultaneously receiving multiple bipolar signals and ECG signals, and receiving an indication of the degree of physical contact of the electrodes with the tissue being diagnosed from a contact force sensor. This step and other possible steps have been intentionally omitted from the disclosure herein to provide a more simplified flow chart.

[0047] PSA mapping

[0048] Figure 4 is a schematic graphical volume rendering of an EP map 400 that graphically indicates a left atrial region 404 found to exhibit PSA according to one example of the present disclosure. The EP map 400 shows an anatomical surface superimposed with graphically encoded EP parameters 402, such as bipolar potential amplitude or LAT. Alternatively, Figure 4Only the anatomical surface can be shown. Figure 4 , dark regions 404 are coded to indicate one or more locations (e.g., clusters of locations) identified by the disclosed technology as exhibiting PSA. As shown, processor 56 delineates a boundary 405 around each region 404 that includes a cluster of locations exhibiting PSA. A physician can use the delineation 405 to plan ablation to eliminate the arrhythmia in that region.

[0049] If the PSA indication is superimposed on another EP layer (such as the EP layer of bipolar potentials), the physician can evaluate the correlation between the areas of proarrhythmogenic indication to refine the ablation plan. For example, an area showing both PSA and low bipolar potentials can be considered a scar area that needs to be homogenized to eliminate slow conduction pathways therein.

[0050] Example

[0051] Example 1

[0052] A method includes receiving a cardiac signal (21) sensed by an electrode (26) at a location in a patient's heart (12), the cardiac signal (21) including signal components induced by corresponding activations. Finding and annotating (204) the signal components in the cardiac signal (21). Calculating (206) corresponding time differences between the annotations and the corresponding activations. Based on the time differences (206), identifying one or more cardiac tissue locations that exhibit progressively slower activations (PSAs). Presenting an EP map (400) of at least a portion of the heart (12) to a user includes providing a graphical indication (405) of the one or more tissue locations that exhibit the PSAs.

[0053] Example 2

[0054] The method of embodiment 1, wherein the activation comprises applying a pacing stimulus to the heart (12).

[0055] Example 3

[0056] A method according to any one of Examples 1 and 2, wherein the activation comprises naturally occurring sinus rhythm activation of the heart (12).

[0057] Example 4

[0058] The method of any one of Examples 1 to 3, wherein identifying the tissue locations exhibiting the PSA comprises identifying one or more tissue locations that exhibit a monotonically increasing time difference (206) over at least three consecutive cardiac cycles.

[0059] Example 5

[0060] The method of any one of embodiments 1 to 4, wherein providing the graphical indication (405) comprises drawing a boundary around the cluster of tissue locations exhibiting the PSA.

[0061] Example 6

[0062] The method according to any one of embodiments 1 to 5, wherein receiving the cardiac signal (21) includes receiving a unipolar electrogram and a bipolar electrogram acquired using a catheter (14).

[0063] Example 7

[0064] A method according to any one of embodiments 1 to 6, wherein annotating (204) the signal (21) component includes annotating a bipolar electrogram, a unipolar electrogram or a multipolar electrogram.

[0065] Example 8

[0066] A system includes an interface (30) and a processor (56). The interface (30) is configured to receive a cardiac signal (21) sensed by an electrode (26) at a location in a patient's heart (12), the cardiac signal (21) including a signal component induced by a corresponding activation. The processor (56) is configured to (i) find and annotate (204) the signal component in the cardiac signal (21), (ii) calculate a corresponding time difference (206) between the annotation (204) and the corresponding activation, (iii) identify one or more cardiac tissue locations exhibiting a progressively slowing activation (PSA) based on the time difference (206), and (iv) present an EP map (400) of at least a portion of the heart (12) to a user, including providing a graphical indication (405) of the one or more tissue locations exhibiting the PSA.

[0067] It should be understood that the above embodiments are cited by way of example, and the present disclosure is not limited to what is 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 comprising: receiving a cardiac signal sensed by an electrode at a location in a heart of a patient, the cardiac signal including a signal component induced by a corresponding activation; finding and annotating the signal components in the cardiac signal; Calculate the corresponding time difference between the annotation and the corresponding activation; identifying one or more cardiac tissue locations that exhibit progressively slower activation (PSA) based on the time difference; as well as An EP map of at least a portion of the heart is presented to a user, including providing a graphical indication of the one or more tissue locations exhibiting the PSA.

2. The method according to claim 1, wherein The activation includes applying a pacing stimulus to the heart.

3. The method according to claim 1, wherein The activation comprises naturally occurring sinus rhythm activation of the heart.

4. The method according to claim 1, wherein Identifying the tissue locations exhibiting the PSA includes identifying one or more tissue locations that exhibit a monotonically increasing time difference over at least three consecutive cardiac cycles.

5. The method according to claim 1, wherein Providing the graphical indication includes drawing a boundary around the cluster of tissue locations exhibiting the PSA.

6. The method according to claim 1, wherein Receiving the cardiac signal includes receiving a unipolar electrogram and a bipolar electrogram acquired using a catheter.

7. The method according to claim 1, wherein Annotating the signal component includes annotating a bipolar electrogram, a unipolar electrogram, or a multipolar electrogram.

8. A system comprising: an interface configured to receive a cardiac signal sensed by an electrode at a location in a patient's heart, the cardiac signal including a signal component induced by a corresponding activation; as well as A processor configured to: finding and annotating the signal components in the cardiac signal; Calculate the corresponding time difference between the annotation and the corresponding activation; identifying one or more cardiac tissue locations that exhibit progressively slower activation (PSA) based on the time difference; as well as An EP map of at least a portion of the heart is presented to a user, including providing a graphical indication of the one or more tissue locations exhibiting the PSA.

9. The system according to claim 8, wherein: The activation includes applying a pacing stimulus to the heart.

10. The system according to claim 8, wherein: The activation comprises naturally occurring sinus rhythm activation of the heart.

11. The system according to claim 1, wherein: The processor is configured to identify the tissue locations exhibiting the PSA by identifying one or more tissue locations that exhibit a monotonically increasing time difference over at least three consecutive cardiac cycles.

12. The system according to claim 8, wherein: The processor is configured to provide the graphical indication by drawing a boundary around a cluster of tissue locations exhibiting the PSA.

13. The system according to claim 8, wherein: The interface is configured to receive the cardiac signal by receiving a unipolar electrogram and a bipolar electrogram acquired using a catheter.

14. The system according to claim 8, wherein: The processor is configured to annotate the signal component by annotating a bipolar electrogram, a unipolar electrogram, or a multipolar electrogram.

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