System and method for evaluating conduction blockages within tissues

Abstract

To provide systems, apparatuses and methods for automated assessment of a conduction block in tissue.SOLUTION: A conduction block across a lesion in tissue can be assessed by applying a pacing signal to the tissue on one side of the lesion and sensing electrophysiological activity in the tissue on the opposite side of the lesion. A signal processor, such as may be incorporated into an electroanatomical mapping system, analyzes the sensed electrophysiological activity for a response evoked by the pacing signal, and outputs an indicator of conduction block status. More specifically, when a preset number of consecutive pacing pulses do not yield an evoked response, an indicator of a block can be output; conversely, when a preset number of consecutive pacing pulses do yield an evoked response, an indicator of no block can be output.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] This application claims the benefit of U.S. Provisional Application No. 63 / 490,887, filed Mar. 17, 2023, which is hereby incorporated herein by reference in its entirety.

Background Art

[0002] The present disclosure generally relates to electrophysiological procedures and treatments for cardiac rhythm disorders, including but not limited to atrial fibrillation. In particular, the present disclosure relates to systems, devices, and methods for evaluating the effectiveness of ablation lesions formed to block abnormal conduction pathways.

[0003] Various cardiac rhythm disorders are known. Similarly, it is known that certain cardiac rhythm disorders can be treated by forming ablation lesions in the heart to block abnormal conduction pathways that may cause or contribute to arrhythmias.

[0004] For example, atrial fibrillation is understood to result from chaotic electrical activity in the myocardium. One well-known treatment for atrial fibrillation is to form lesions that isolate one or more pulmonary veins from the left atrium, a so-called pulmonary vein isolation, or PVI procedure.

[0005] Those skilled in the art will be familiar with the various techniques that can be used to form PVI lesions. These include, but are not limited to, radiofrequency (RF) ablation, cryoablation, microwave ablation, laser ablation, high-intensity focused ultrasound (HIFU) ablation, pulsed-field ablation (PFA), also known as irreversible electroporation (IRE).

[0006] Regardless of the technique used to create the PVI injury, practitioners often want to confirm whether the injury has produced the desired effect of blocking electrical conduction between the pulmonary veins and the left atrium. "Outlet block" is confirming that the injury has blocked conduction from the pulmonary veins to the left atrium, which could maintain atrial fibrillation. "Inlet block" is the opposite, blocking conduction from the left atrium to the pulmonary veins. Achieving both an outlet block and an inlet block is known as a "complete block" or "bidirectional block."

[0007] Exit block can be tested by pacing the tissue upstream (pulmonary veins) of the PVI injury and sensing the electrophysiological activity downstream (left atrium) of the PVI injury. If the upstream pacing signal elicits a response downstream of the PVI injury, exit block has not been achieved.

[0008] However, known approaches to testing for exit blocks are manual and labor-intensive. The practitioner must properly pace the upstream tissue and interpret the electrophysiological signals sensed downstream of the injury. As a result, it can take several minutes for the practitioner to determine whether a block has been achieved. [Overview of the project] [Problems that the invention aims to solve]

[0009] This specification discloses a method for evaluating conduction block across tissue damage. The method includes the steps of: applying a pacing signal to tissue on a first side of the injury, wherein the pacing signal comprises a plurality of pacing pulses; sensing electrophysiological activity in tissue on a second side of the injury, wherein the second side of the injury is opposite to the first side of the injury; analyzing the sensed electrophysiological activity in a signal processing device for an evoked response to the pacing signal; and outputting an indicator of conduction block status via the signal processing device. The indicator of conduction block status may be an indicator of conduction block if a preset number of consecutive pacing pulses do not elicit an evoked response, an indicator of the absence of conduction block if a preset number of consecutive pacing pulses elicit an evoked response, and an indicator of uncertain block status otherwise. The indicator of conduction block status may include a visual indicator of conduction block status, an audible indicator of conduction block status, and / or a tactile indicator of conduction block status.

[0010] In embodiments of the present disclosure, the step of applying a pacing signal to tissue on a first side of injury includes the step of applying a pacing signal to the tissue using a first plurality of electrodes located on the first side of injury, and the step of sensing electrophysiological activity in tissue on a second side of injury includes the step of sensing electrophysiological activity using a second plurality of electrodes located on the second side of injury. The first plurality of electrodes and the second plurality of electrodes may be attached to a common catheter. For example, the common catheter may comprise a proximal shaft and a plurality of distal expandable splines, with the first plurality of electrodes attached to the distal expandable splines and the second plurality of electrodes attached to the proximal shaft.

[0011] A first increment of ablation therapy can be applied to the tissue before the step of applying a pacing signal to the tissue using a first plurality of electrodes located on the first side of the injury. In some embodiments of the present disclosure, the first increment of ablation therapy is applied to the tissue using a subset of the first plurality of electrodes.

[0012] According to certain embodiments disclosed herein, a second set of electrodes can be attached to a set of catheters. Electrophysiological activity in the tissue on the second side of the injury can also be sensed with surface electrocardiogram leads.

[0013] The pacing signal can be applied to the tissue using all of the first set of electrodes simultaneously. Alternatively, the pacing signal can be applied to the tissue using pairs of electrodes selected from the first set of electrodes sequentially. When the pacing signal is applied using pairs of electrodes selected from the first set of electrodes sequentially, the indicator of the absence of conduction block may further include an indicator of the location of the injury gap.

[0014] This method may include a step of delaying by a preset blanking interval between the steps of applying a pacing signal to the tissue on the first side of the injury and analyzing the electrophysiological activity sensed in the signal processing device for the induced response by the pacing signal.

[0015] Optionally, the signal processing unit can also output a confidence value for the indicator of the conduction block state.

[0016] In a signal processing device, the step of analyzing the perceived electrophysiological activity for an induced response by a pacing signal may include the step of the signal processing device analyzing the perceived electrophysiological activity for signal amplitudes exceeding a preset noise level threshold. The signal processing device may use a pre-set noise level threshold, or it may determine the preset noise level threshold based on the amplitude of electrophysiological activity perceived during the rest interval.

[0017] This disclosure also provides a system for evaluating conduction block across injury within tissue. The system comprises a pacing system configured to apply a pacing signal to tissue on a first side of injury, wherein the pacing signal comprises a plurality of pacing pulses; a sensing system configured to sense electrophysiological activity in tissue on a second side of injury, wherein the second side of injury is opposite to the first side of injury; and a conduction block signal processing unit. The conduction block signal processing unit is configured to analyze the sensed electrophysiological activity for evoked responses by the pacing signal and to output an indicator indicating the state of conduction block. The indicator of conduction block may be an indicator of conduction block if a preset number of consecutive pacing pulses do not induce an evoked response, an indicator of no conduction block if a preset number of consecutive pacing pulses do induce an evoked response, and an indicator of uncertain block state otherwise.

[0018] Two or more of the pacing system, sensing system, and conduction block signal processing system may be integrated into the electroanatomical mapping system.

[0019] The system can also further include a multi - electrode catheter operably coupled to both the pacing system and the sensing system. The multi - electrode catheter includes a first plurality of electrodes operably coupled to the pacing system to apply a pacing signal to the tissue on the first side of the injury, and a second plurality of electrodes operably coupled to the sensing system to sense electrophysiological activity in the tissue on the second side of the injury. The first plurality of electrodes are located on the distal side of the second plurality of electrodes on the multi - electrode catheter.

[0020] The pacing system can be configured to apply a pacing signal to the tissue using each of the first plurality of electrodes simultaneously.

[0021] The conduction block signal processor can be further configured to determine a preset number of consecutive pacing pulses as a function of at least one of the intrinsic heart rate and the rate of the pacing signal.

[0022] The foregoing and other aspects, features, details, utilities, and advantages of the present invention will become apparent by reading the following description and claims and by examining the accompanying drawings.

Brief Description of the Drawings

[0023] [Figure 1A] It is a block diagram of a system for evaluating a conduction block according to an aspect of the present disclosure. [Figure 1B] It is a block diagram of a system for evaluating a conduction block according to an aspect of the present disclosure. [Figure 2] It shows an exemplary catheter that can be used in connection with an aspect of the present disclosure. [Figure 3] It is a flowchart of representative steps that can be implemented according to an aspect of the present disclosure. [Figure 4A] It is an exemplary pacing signal. [Figure 4B] It is an exemplary electrophysiological activity signal sensed in response to the pacing signal shown in Figure 4A. [Figure 5A]Shows the block state indicator according to the embodiments disclosed in this specification. [Figure 5B] Shows the block state indicator according to the embodiments disclosed in this specification. **Embodiments for Carrying Out the Invention**

[0024] Although multiple embodiments are disclosed, further embodiments of the present disclosure will be apparent to those skilled in the art from the following detailed description, which illustrates and describes exemplary embodiments. Accordingly, the drawings and the detailed description are to be regarded as being essentially exemplary and not restrictive.

[0025] The present disclosure provides a system, apparatus, and method for automatically evaluating conduction blocks in tissue. For illustrative purposes, aspects of the present disclosure will be described with reference to evaluating conduction blocks resulting from pulmonary vein isolation (PVI) procedures. However, those skilled in the art will understand how to apply the teachings herein to evaluate other injuries, scars, and conduction blocks across low voltage regions, anatomical boundaries, functional blocks, or delays.

[0026] Figures 1A and 1B are block diagrams of an exemplary system 10 (shown as 10a and 10b, respectively) for evaluating conduction blocks in tissue (e.g., tissue within heart 12) according to various aspects of the present disclosure. More specifically, Figure 1A shows an embodiment of the present disclosure interconnecting various individual hardware components and software components, and Figure 1B shows an embodiment of the present disclosure integrating multiple aspects described herein into a single hardware component referred to as an ablation and test device.

[0027] As shown in Figure 1A, system 10a comprises an ablation generator 14. Although the ablation generator 14 is illustrated as a pulsed-field ablation (PFA) generator, it should be understood that other ablation modes (e.g., radio frequency (RF) ablation, cryoablation, microwave ablation, etc.) are within the spirit and scope of this disclosure, insofar as it may be desirable to evaluate the block achieved by the ablation damage, regardless of how the damage was formed.

[0028] System 10a further comprises an electroanatomical mapping system 16, such as Abbott Laboratories' (Abbott Park, Illinois) EnSite®X, EnSite®Velocity®, or EnSite Precision® electrophysiological mapping and visualization systems, and a pacing / sensing system 18, such as the WorkMate Claris® system, which can be used in combination with Abbott Laboratories' EP-4® cardiac stimulator. The functions and operations of the ablation generator 14, the mapping system 16, and the pacing / sensing system 18 will be well known to those skilled in the art, and will therefore be described herein only to the extent necessary to understand this disclosure.

[0029] The user interface 20 allows the practitioner to interact with system 10a and view the output from system 10a. Further details of the user interface 20 are provided below.

[0030] The ablation generator 14, mapping system 16, and / or pacing / sensing system 18 can be operably connected to the catheter 22. A typical catheter 22 is described in more detail below.

[0031] Those skilled in the art will further understand that, although only a single catheter 22 is shown and described for illustrative purposes from the following disclosure, the teachings herein can be applied using multiple catheters. For example, system 10a may incorporate a first catheter operably connected to an ablation generator 14 to deliver ablation energy to tissues within the heart 12, and an additional catheter operably connected to a pacing / sensing system 18 to test for conduction block. In another example, system 10a may utilize two (or more) catheters operably connected to the pacing / sensing system 18, some of which may be dedicated to pacing and others to sensing electrophysiological activity. Indeed, in certain embodiments of this disclosure, it may be particularly desirable to use multiple catheters to sense the electrophysiological activity of the heart 12.

[0032] Figure 1B shows a system 10b similar to system 10a shown in Figure 1A. However, in Figure 1B, the ablation generator, pacing / sensing function, signal processing function, and user interface are integrated into a single ablation and test device 24, which is operably connected to the catheter 22.

[0033] As shown by the dashed line, system 10b may optionally be equipped with an electroanatomical mapping system 16 and / or a dedicated pacing / sensing system 18.

[0034] Figure 2 depicts a catheter 22 positioned within the heart 12 to assess conduction block over PVI injury in the pulmonary veins 26. As shown in Figure 2, the catheter 22 includes multiple electrodes 28. To bring electrodes 28a–28d into contact with the walls of the pulmonary veins 26, a first set of electrodes 28 (designated 28a–28d as seen in Figure 2, but it will be understood by those skilled in the art that additional such electrodes 28 may be positioned on the side of the catheter 22 not seen in Figure 2) are attached distally to an expandable member 30, such as a basket incorporating multiple splines as shown. A second set of electrodes 28, designated 28e and 28f, are attached proximal to the shaft 32 of the catheter 22.

[0035] It should be understood that the number and arrangement of electrodes 28 shown in Figure 2 are merely illustrative. In fact, variations in the number and arrangement of electrodes 28 will be evident from the following disclosures, including variations in which electrodes 28 are arranged across two or more catheters. For example, electrodes 28a–28d may be attached to a first catheter used for pacing, and electrodes 28e and 28f may be attached to a second catheter used for sensing.

[0036] Similarly, please understand that the specific catheter configuration shown in Figure 2 is merely an example. Other suitable catheter designs, but not limited to these, include balloon catheters, grid catheters, linear catheters, lattice catheters, circular catheters, and spiral catheters.

[0037] An exemplary method for evaluating conduction blocks according to aspects of this disclosure will be described with reference to a flowchart 300 of typical steps shown in Figure 3. The flowchart 300 is first described in general terms, and further details of the typical steps therein are given following that general description.

[0038] In general, flowchart 300 depicts several exemplary steps, which can be performed by system 10, or more specifically, by one or more signal processing devices within system 10. As used herein, the term “signal processing device” includes hardware-based and software-based processing of both analog and digital signals. Accordingly, the typical steps described below can be implemented in hardware, in software, or as a combination of hardware and software. Furthermore, signal processing may be performed in a single device (for example, via a signal processing device incorporated into the ablation and test device 24 of system 10b) or distributed across multiple devices (for example, via dedicated signal processing devices incorporated into the ablation generator 14 and pacing / sensing system 18 of system 10a).

[0039] In block 302, an increment of ablation is applied to form a PVI injury in the pulmonary vein 26. In embodiments of this disclosure, the ablation energy can be applied using a subset of the first set of electrodes 28a-28d to simultaneously form the entire PVI injury (referred to as a "one-shot" PVI injury). However, as described above, ablation may be performed using a dedicated ablation catheter before inserting the catheter 20 equipped with electrodes 28 for conduction block evaluation.

[0040] Steps 302–312 of flowchart 300 generally relate to evaluating the effectiveness of the PVI injury formed in block 302 in achieving conduction block. For ease of explanation, steps 302–310 are described with reference to the evaluation of exit block (i.e., evaluation of whether the PVI injury has blocked the natural conduction of cardiac excitation from the pulmonary veins 26 to the left atrium). However, those skilled in the art with ordinary art will understand how the teachings herein can be adapted to evaluate inlet block and / or complete block.

[0041] In block 304, a pacing signal is applied to the tissue on the first side of the injury (for example, via the pacing / sensing system 18 or via the pacing function of the ablation and test apparatus 24). When evaluating the exit block, the upstream (distal) side of the injury is the first side.

[0042] In block 306, electrophysiological activity on the second side of the injury is sensed (for example, via the pacing / sensing system 18 or via the sensing function of the ablation and test apparatus 24). When evaluating the exit block, the downstream (proximal) side of the injury becomes the second side.

[0043] In block 308, the signal processing unit analyzes the electrophysiological activity sensed in block 306 and evaluates conduction block by detecting any evoked response (if any) caused by the pacing signal applied in block 304. As will be explained in more detail below, if an evoked response is detected, conduction block is likely not achieved, and conversely, if no evoked response is detected, conduction block is likely achieved.

[0044] In block 310, the signal processing device outputs the results of the conduction block analysis to the user (for example, via the user interface 20) as an indicator of the conduction block. The indicator of the conduction block typically reflects a BLOCK state, a NO BLOCK state, or an UNKNOWN (or UNCERTAIN) state.

[0045] In any block 312, system 10 can calculate and output a confidence value that reflects the probability that the analysis results obtained in block 308 are correct. Details of block 312 will be described later.

[0046] Pacing details (Block 304) In embodiments of the present disclosure, the pacing signal for block 304 is applied using a plurality of first electrodes 28a-28d located upstream of or directly above the injury L, as shown in Figure 2. In embodiments of the present disclosure, the pacing signal for block 304 can be applied simultaneously using all of the first plurality of electrodes within a predetermined number of pulses (referred to herein as “simultaneous pacing”). This can advantageously accelerate the process of evaluating conduction blocks compared to a conventional (manual) approach (referred herein as “pairwise continuous pacing”) in which each pair of electrodes is used separately and sequentially for pacing over multiple pulses.

[0047] However, in certain embodiments of this disclosure, the pacing signal for block 304 may utilize pairwise continuous pacing (over multiple pulsations, e.g., electrodes 28a and 28b, then electrodes 28b and 28c). While the determination of the block state may be slower than with simultaneous pacing, the pairwise continuous pacing approach may enhance the ability to identify where conduction block is not present on the periphery of the pulmonary veins 26, whereas simultaneous pacing may only provide a binary BLOCK or NO BLOCK indicator result.

[0048] In fact, it is explicitly intended that simultaneous pacing be used first, and if NO BLOCK is detected using simultaneous pacing, it will automatically switch to pairwise sequential pacing for further analysis to identify areas where no blocks exist.

[0049] In either case, Figure 4A depicts a typical pacing signal 400 that includes multiple pacing pulses 402 and has a period length 404 (i.e., the interval between pacing pulses 402). In sensing step 306, in order to minimize the possibility of natural tissue excitation being mistaken for an evoked response, the period length 404 of the pacing signal 400 is set to minimize the possibility of N-of-M pacing (i.e., pacing at or multiples of the natural period length). Thus, the pacing signal 400 can have a preset period length 404 that is slightly shorter than a typical natural period length, such as between approximately 500 ms and approximately 600 ms.

[0050] The system 10 may be programmed to warn the user if the preset period length 404 needs to be adjusted. In fact, in certain embodiments of the present disclosure, if the preset period length 404 is not properly set, the system 10 may suspend the analysis block 308 and / or the instruction block 310 until the user adjusts it to an appropriate value.

[0051] The period length 404 of the pacing signal 400 may also be determined from patient-specific electrophysiological data. For example, a patient's intrinsic period length can be measured using surface electrocardiography (ECG) and / or intracardiac electroencephalography (EGM) (e.g., during sinus rhythm or threshold pacing) according to methods well known to those skilled in the art. Once the intrinsic period length is measured, the period length 404 of the pacing signal 400 can be set to a value slightly different from the intrinsic period length, such as about 60% to about 90% of the intrinsic period length, or about 100 ms to about 400 ms smaller than the intrinsic period length.

[0052] Furthermore, in addition to considering the intrinsic period length when determining the period length 404 of the pacing signal 400, the system 10 can also consider the length of the atrioventricular interval.

[0053] Those skilled in the art will also understand the relationship between the appropriate period length 404 of the pacing signal 400 and the length of the preset analysis interval (which will be described in more detail below).

[0054] Those skilled in the art will also understand that the amplitude and duration (width) of each pulse 402 within the pacing signal 400 should be sufficient to capture the pacing tissue while avoiding long-range capture. As just one example, embodiments of the present disclosure use a preset amplitude of about 5 mA and a preset width of about 2 ms.

[0055] In other embodiments of this disclosure, the amplitude and width of each pulse 402 can be determined from patient-specific electrophysiological data, such as ECG and / or EGM signals, acquired during the procedure. For example, before the formation of PVI damage (e.g., before step 302), the conduction block assessment process described herein (e.g., steps 304-310) is expected to result in NO BLOCK. If, instead, it results in BLOCK before ablation, it is likely that the amplitude and / or width of pulse 402 is too small to capture the tissue. This suggests that the amplitude and / or width of pulse 402 should be increased for conduction block assessment after ablation (e.g., after step 302).

[0056] As another example, if there is suspicion that remote capture after ablation may cause a (false) NO BLOCK result, it may be desirable to reduce the amplitude of pulse 402, thereby minimizing the possibility that block 304 pacing will cause remote capture and lead to a false NO BLOCK result.

[0057] Detection details (block 306) In embodiments of this disclosure, electrodes 28e and 28f located downstream of the damaged area, as shown in Figure 2, are used to sense the bipolar electrograph. Figure 4B shows a typical bipolar electrograph 406 sensed at block 306 by electrodes 28e and 28f. Within this electrograph 406, to help the reader understand this disclosure, the pacing pulse 402 is annotated with "P" in Figure 4B, and the evoked response (a vertical line extending downward to approximately -0.5mV) is annotated with "ER".

[0058] However, other approaches to sensing electrophysiological activity within tissues are also possible. For example, an omnipolar electrogram can be sensed from within the left atrium using an additional catheter (e.g., a high-density (HD) grid catheter such as Abbott Laboratories' Advisor® HD grid mapping catheter or Sensor Enabled®). U.S. Patent Application Publication 2018 / 0296111 describes the calculation of an omnipolar electrogram and is incorporated herein by reference as being fully described herein.

[0059] In other embodiments of the present disclosure, electrophysiological activity can be sensed using a catheter located in the coronary sinus. Surface ECG signals may also be advantageously employed in the sensing block 306.

[0060] Combinations of the aforementioned methods are also possible. For example, electrophysiological activity can be sensed using both electrodes 28e, 28f and a surface ECG, or using both electrodes 28e, 28f and an HD grid catheter in the left atrium.

[0061] Analysis details (Block 308) In block 308, system 10 analyzes the electrophysiological activity (e.g., signal 406) sensed in block 306 to detect the evoked response from the pacing signal 400. To minimize the possibility of detecting upstream pacing artifacts rather than the evoked response, a preset blanking interval (e.g., approximately 20 ms) of signal 406 following each pacing pulse 402 is not analyzed for the evoked response; rather, only a preset analysis interval (e.g., approximately 80 ms) of signal 406 following the preset blanking interval is analyzed for the evoked response.

[0062] System 10 can detect an evoked response by searching for amplitude peaks of signal 406 that exceed a noise level threshold. In embodiments of this disclosure, the noise threshold is preset between approximately 0.03 mV and approximately 0.04 mV.

[0063] In other embodiments of the present disclosure, the noise level threshold can be determined from treatment-specific electrophysiological data, such as ECG and / or EGM signals, obtained during the treatment. For example, a baseline noise signal can be identified within the EGM signal obtained during the treatment (e.g., during the rest interval between pulses), and the amplitude of the baseline noise signal can be used as the noise level threshold (or, alternatively, the noise level threshold can be determined by setting the noise threshold slightly above the amplitude of the baseline noise signal).

[0064] Other approaches to detecting evoked responses in block 308 are possible. For example, instead of detecting evoked responses based on the amplitude of signal 406, system 10 may employ other signal characteristics, including but not limited to the absolute value of signal 406, the square of signal 406, the root mean square of signal 406, the peak frequency of signal 406, the first derivative of signal 406 with respect to time, and various energy-based methods. It may also be desirable to filter signal 406 before analysis (e.g., using a bandpass filter that allows frequencies between approximately 30 Hz and 300 Hz).

[0065] As described above, the system 10 evaluates the state of conduction block by evaluating the signal 406 for the evoked response by the pacing pool 402, and determines the state of conduction block when it detects at least a preset number of identical consecutive results. In certain embodiments of this disclosure, the preset number is 2. However, this is merely illustrative, and it should be understood that the more identical and consecutive results there are, the more reliable the determination of the state of conduction block reached in block 308, but similarly, the longer the time required to reach such a determination. For example, in some embodiments of this disclosure, the preset number of identical and consecutive results can be user-adjustable. As another example, in additional embodiments of this disclosure, the system 10 can analytically determine the preset number of identical and consecutive results as a function of intrinsic heart rate and / or pacing rate.

[0066] If system 10 does not detect an evoked response in signal 406 over a preset number of consecutive pacing pulses 402, system 10 can determine that a conducted block has been achieved. On the other hand, if system 10 detects an evoked response in signal 406 over a preset number of consecutive pacing pulses 402, system 10 can determine that a conducted block has not been achieved. Otherwise (for example, until the required number of consecutive pacing pulses 402 produce the same result), system 10 remains in an uncertain blocked state.

[0067] As an example, let's re-examine Figures 4A and 4B. System 10 starts in the UNKNOWN state. No evoked response is observed in signal 406 after pulse 402a (immediately after 32 seconds), but system 10 always remains in the UNKNOWN state even after the first pulse 402a. Pulse 402b (immediately before 33 seconds) elicits response 408b, but since this is an evoked response following a no evoked response, system 10 remains in the UNKNOWN state. Pulse 402c (immediately after 33 seconds) again does not elicit a response in signal 406, and since there are no two consecutive identical results, system 10 remains in the UNKNOWN state again.

[0068] The next two pulses, 402d and 402e (approximately 34 seconds and 34.5 seconds, respectively), induce responses 408d and 408e in signal 406, respectively. Since the induced response 408d is followed by no induced response, system 10 remains in the UNKNOWN state after pulse 402d. On the other hand, since the induced response 408e is the second consecutive induced response, system 10 transitions to the NO BLOCK state after pulse 402e and can stop the analysis.

[0069] System 10 may incorporate additional analysis to minimize the chances of it mistaking intrinsic atrial depolarization and distant R waves for evoked responses. In particular, evoked responses should occur at relatively consistent timings after the pacing pulse 402. False evoked responses, such as intrinsic depolarization, distant signals, or excessively low-power pacing, do not exhibit the same degree of consistency, especially for pacing period lengths 404 that are similar to the intrinsic period length.

[0070] Accordingly, in embodiments of the present disclosure, the system 10 also checks the timing of the apparent evoked response ER relative to the timing of the pacing pulse P and verifies that it occurs within a preset expected time window (for example, that the apparent evoked response ER does not occur after the preset duration of the pacing pulse P) before concluding that it is actually an evoked response.

[0071] Detailed indicator output (block 310) In block 310, system 10 outputs a BLOCK, NO BLOCK, or UNKNOWN indicator (e.g., via user interface 20) to warn the user of the analysis results in block 308. The indicator can be visual (e.g., output to a display in system 10, which may be part of the electroanatomical mapping system 16, ablation and testing apparatus 24, or user interface 20), audible (e.g., a tone may be emitted when BLOCK is achieved), and / or tactile (e.g., the handle of catheter 22 may vibrate when BLOCK is achieved).

[0072] There are various approaches to visual indicators of block status that practitioners may find useful or desirable in connection with this instruction. For example, in some embodiments of this disclosure, easily understandable text-based annotations (e.g., the term “BLOCK” or the phrase “NO BLOCK”) and / or color codes (e.g., coloring the sensed signal 406 or another signal trace, coloring the graphic representation of the catheter 20, or displaying “signal lights” where yellow indicates UNKNOWN, green indicates BLOCK, and red indicates NO BLOCK) may be output to the user interface 20.

[0073] Figure 5A depicts a visual indicator of block status, which may be particularly advantageous in relation to pairwise continuous pacing. In particular, a three-dimensional representation 500 of the catheter 20 is shown together with a surrounding sectoral indicator 502. The indicator 502 is generally divided into sectors 504a to 504d, which correspond to consecutive pairs of electrodes 28a to 28d used for pacing. These sectors 504a to 504d can be selectively illuminated, shaded, or otherwise highlighted to indicate that they correspond to areas of NO BLOCK.

[0074] Indicator 502 can also be used for simultaneous pacing. In this case, rather than selectively illuminating, shading, or otherwise highlighting individual sectors 504a to 504d, the entire indicator 502 can be illuminating, shading, or otherwise highlighting in the NO BLOCK state.

[0075] As an alternative to a separate fan-shaped indicator 502, a three-dimensional display 500 of the catheter 20 (or part thereof) may be selectively illuminated, shaded, or otherwise highlighted to indicate the NO BLOCK status and / or orientation. Similarly, a three-dimensional model of the heart 12 may be selectively illuminated, shaded, or otherwise highlighted to indicate the NO BLOCK status and / or location.

[0076] In yet another alternative, the three-dimensional display 500 and / or indicator 502 in Figure 5A can be replaced with a more compact two-dimensional indicator 506, for example, as shown in Figure 5B. Of course, the indicator 506 can also be divided into sectors to provide region-specific NO BLOCK indicators.

[0077] Confidence value As described above, in an optional block 312, the system 10 can calculate and output a confidence value that reflects the probability that the analysis result reached in block 308 is correct (for example, that the BLOCK judgment is not a false positive because the pacing signal 400 was insufficient to capture the tissue, or that the NO BLOCK judgment is not a false negative because the detection in signal 406 is a distant activity rather than an elicited response).

[0078] Various factors influence confidence levels. For example, confidence levels increase with each successive, consistent result (e.g., consecutive BLOCK or NO BLOCK results) and decrease if the successive results are inconsistent.

[0079] As another example, the confidence value for the NO BLOCK result may increase as the amplitude of the response of signal 406 after pacing further exceeds the noise threshold. That is, the closer the amplitude of the response of signal 406 after pacing is to the noise threshold, the more likely it is to be noise, and therefore the lower the confidence value should be.

[0080] As another example, the confidence value may decrease as the post-pacing response of signal 406 approaches the edge of the analysis interval. That is, the closer the post-pacing response of signal 406 is to the edge of the analysis interval, the more likely it is to be an artifact rather than an evoked response, and therefore the lower the confidence value should be.

[0081] In this regard, as with the above discussion regarding approaches that can be used to avoid mistaking endogenous atrial depolarization, distant R waves, and other signals for evoked responses, the consistency of timing between the pacing pulse and the evoked response can contribute to the confidence level.

[0082] In yet another example, the suitability or appropriateness of the preset period length 404 of the pacing signal 400 can contribute to the confidence value.

[0083] System 10 can also output a graphical representation of the confidence level. For example, the brightness or intensity of the "signal light" indicator can increase as the confidence level increases. Conversely, if the confidence level falls below a preset threshold, the display may remain in the UNKNOWN state, even if it otherwise determines the limit.

[0084] Although several embodiments have been described in some detail above, those skilled in the art can make numerous modifications to the disclosed embodiments without departing from the spirit or scope of the present invention.

[0085] For example, the teachings herein can be applied in real time (e.g., during an electrophysiological study) or during post-processing (e.g., for data collected during an earlier electrophysiological study).

[0086] As another example, before initiating pacing in block 304, techniques can be employed to evaluate the contact between the electrode 28 and the tissue, such as impedance sensing techniques, to ensure proper contact.

[0087] As yet another example, while exemplary embodiments have been described above with reference to a first set of electrodes for applying a pacing signal on the first side of the injury and a second set of electrodes for sensing electrophysiological activity on the second side of the injury, it is also possible to replace one or both of the first and second sets of electrodes with a single electrode (e.g., a single pacing electrode on the first side of the injury and / or a single sensing electrode on the second side of the injury).

[0088] References to all directions (e.g., up, down, upward, downward, left, right, leftward, rightward, up, down, higher, lower, vertical, horizontal, clockwise, and counterclockwise) are used solely for identification purposes to aid the reader's understanding of the present invention and do not create any particular limitation on the position, direction, or use of the present invention. References to connections (e.g., mounting, joining, connection, etc.) should be interpreted broadly and may include intermediate members between elements and relative movement between elements. Thus, references to connections do not necessarily imply that the two elements are directly connected and in a fixed relationship with one another.

[0089] All matters included in the above description or shown in the accompanying drawings are intended to be illustrative only and not limiting. Modifications to details or structures may be made without departing from the spirit of the invention as defined in the accompanying claims. The following items are elements described in the claims at the time of the international application. (Item 1) A method for evaluating conduction block across tissue damage, A step of applying a pacing signal to the tissue on the first side of the injury, wherein the pacing signal includes a plurality of pacing pulses, A step of sensing electrophysiological activity within the tissue on a second side of the injury, wherein the second side of the injury is opposite to the first side of the injury, In a signal processing device, the steps include analyzing the detected electrophysiological activity in relation to the induced response by the pacing signal, The step of outputting an indicator of the state of the conduction block via the signal processing device, The indicator of the state of the aforementioned conduction block is, If a preset number of consecutive pacing pulses does not induce the aforementioned evoked response, the indicator of the conduction block and, When the aforementioned preset number of consecutive pacing pulses induce the aforementioned evoked response, this serves as an indicator that there is no conduction block. Otherwise, including an indicator of the uncertain block state, method. (Item 2) The step of applying the pacing signal to the tissue on the first side of the injury includes the step of applying the pacing signal to the tissue using a first plurality of electrodes located on the first side of the injury, The step of sensing the electrophysiological activity in the tissue on the second side of the injury includes the step of sensing the electrophysiological activity using a second plurality of electrodes located on the second side of the injury. The method described in item 1. (Item 3) The method according to item 2, wherein the first plurality of electrodes and the second plurality of electrodes are attached to a common catheter. (Item 4) The aforementioned common catheter comprises a proximal shaft and a plurality of distal expandable splines, The first plurality of electrodes are attached to the distal plurality of expandable splines, The method according to item 3, wherein the second plurality of electrodes are attached to the proximal shaft. (Item 5) The method according to item 3, further comprising the step of applying a first increment of ablation treatment to the tissue before the step of applying the pacing signal to the tissue using the first plurality of electrodes located on the first side of the injury. (Item 6) The method of item 5, wherein the step of applying the first increment of the ablation treatment to the tissue includes applying the first increment of the ablation treatment to the tissue using a subset of the first plurality of electrodes. (Item 7) The method described in item 2, wherein the additional 2 electrodes are attached to the additional catheters. (Item 8) The method of item 2, wherein the step of applying the pacing signal to the tissue using the first plurality of electrodes located on the first side of the injury includes the step of applying the pacing signal to the tissue using all of the first plurality of electrodes simultaneously. (Item 9) The method of item 2, wherein the step of applying the pacing signal to the tissue using the first plurality of electrodes located on the first side of the injury includes the step of applying the pacing signal to the tissue using a pair of electrodes selected from the first plurality of electrodes in sequence. (Item 10) The method according to item 9, wherein the indicator of the absence of the conduction block further includes an indicator of the location of the damaged gap. (Item 11) The method of item 2, wherein the step of sensing the electrophysiological activity in the tissue on the second side of the injury further includes the step of sensing the electrophysiological activity using surface electrocardiogram leads. (Item 12) The steps include applying the pacing signal to the tissue on the first side of the injury, The signal processing device includes the steps of analyzing the detected electrophysiological activity in relation to the induced response caused by the pacing signal, The method according to item 1, further comprising a step of delaying by a preset blanking interval. (Item 13) The method according to item 1, wherein the indicator for the state of conduction block includes one or more of a visual indicator for the state of conduction block, an audible indicator for the state of conduction block, and a tactile indicator for the state of conduction block. (Item 14) The method according to item 1, further comprising the step of outputting a confidence value of an indicator of the state of the conduction block via the signal processing device. (Item 15) The method according to item 1, wherein the step of analyzing the sensed electrophysiological activity for the induced response by the pacing signal in the signal processing device includes the step of the signal processing device analyzing the sensed electrophysiological activity for signal amplitudes exceeding a preset noise level threshold. (Item 16) The method according to item 15, wherein the signal processing device determines the preset noise level threshold according to the amplitude of the electrophysiological activity sensed during the rest interval. (Item 17) A system for evaluating conduction block across tissue damage, A pacing system configured to apply a pacing signal to the tissue on the first side of the injury, wherein the pacing signal includes a plurality of pacing pulses, A sensing system configured to sense electrophysiological activity within the tissue on the second side of the injury, wherein the second side of the injury is opposite to the first side of the injury, and the sensing system Conduction block signal processing device, Equipped with, The conduction block signal processing device is configured to analyze the electrophysiological activity detected by the pacing signal and output an indicator of the conduction block state. The indicator of the state of the aforementioned conduction block is, If a preset number of consecutive pacing pulses does not induce the aforementioned evoked response, the indicator of the conduction block and, When the aforementioned preset number of consecutive pacing pulses induce the aforementioned evoked response, this serves as an indicator that there is no conduction block. Otherwise, including an indicator of the uncertain block state, system. (Item 18) The system according to item 17, wherein the pacing system, the sensing system, and the conduction block signal processing device are integrated into an electroanatomical mapping system. (Item 19) The system further comprises a multi-electrode catheter operably coupled to both the pacing system and the sensing system, The aforementioned multi-electrode catheter is A plurality of first electrodes operably coupled to the pacing system to apply the pacing signal to the tissue on the first side of the injury, The sensing system comprises a plurality of second electrodes operably coupled to the sensing system for sensing the electrophysiological activity in the tissue on the second side of the injury, The system according to item 17, wherein the first plurality of electrodes are located distal to the second plurality of electrodes on the multi-electrode catheter. (Item 20) The pacing system according to item 19, wherein the pacing system is configured to apply the pacing signal to the tissue using each electrode of the first plurality of electrodes simultaneously. (Item 21) The conduction block signal processing device is further configured to determine the preset number of consecutive pacing pulses as a function of at least one of the intrinsic heart rate and the rate of the pacing signal, according to item 17.

Claims

1. A method by which a computer evaluates conduction blockage across damage within tissue, The steps include: when a pacing signal including a plurality of pacing pulses is applied to the tissue on the first side of the injury, the computer senses electrophysiological activity in the tissue on the second side of the injury, wherein the second side of the injury is opposite to the first side of the injury; The computer analyzes the detected electrophysiological activity in relation to the induced response by the pacing signal, The computer includes the step of outputting an indicator of the state of the conduction block, The indicator of the state of the aforementioned conduction block is, If a preset number of consecutive pacing pulses do not induce the aforementioned evoked response, this serves as an indicator that conduction block has been achieved. When the aforementioned preset number of consecutive pacing pulses induce the aforementioned evoked response, this serves as an indicator that there is no conduction block. Otherwise, including an indicator of the uncertain block state, method.

2. The step of sensing the electrophysiological activity in the tissue on the second side of the injury includes the step of the computer sensing the electrophysiological activity using a second plurality of electrodes located on the second side of the injury when the pacing signal is applied to the tissue using a first plurality of electrodes located on the first side of the injury, The method according to claim 1.

3. The method according to claim 2, wherein the first plurality of electrodes and the second plurality of electrodes are attached to a common catheter.

4. The aforementioned common catheter comprises a proximal shaft and a plurality of distal expandable splines, The first plurality of electrodes are attached to the distal plurality of expandable splines, The method according to claim 3, wherein the second plurality of electrodes are attached to the proximal shaft.

5. The method according to claim 3, wherein the computer senses the electrophysiological activity in the tissue on the second side of the injury when a first increment of ablation treatment is applied to the tissue before the pacing signal is applied to the tissue, using the first plurality of electrodes located on the first side of the injury.

6. The method of claim 5, wherein the computer senses the electrophysiological activity in the tissue on the second side of the injury when a first increment of the ablation treatment is applied to the tissue using a subset of the first plurality of electrodes.

7. The method according to claim 2, wherein the second plurality of electrodes are attached to a plurality of catheters.

8. The method according to claim 2, wherein the computer senses the electrophysiological activity in the tissue on the second side of the injury when the pacing signal is applied to the tissue using all of the first plurality of electrodes simultaneously.

9. The method according to claim 2, wherein the computer senses the electrophysiological activity in the tissue on the second side of the injury when the pacing signal is applied to the tissue using sequential pairs of electrodes selected from the first plurality of electrodes.

10. The method according to claim 9, wherein the indicator of the absence of the conduction block further includes an indicator of the location of the damaged gap.

11. The method according to claim 2, wherein the step of sensing electrophysiological activity in the tissue on the second side of the injury further includes the step of the computer sensing the electrophysiological activity using surface electrocardiogram leads.

12. The method according to claim 1, further comprising the step of the computer delaying the induced response by the pacing signal by a preset blanking interval, after the pacing signal has been applied to the tissue on the first side of the injury, and before the step of analyzing the sensed electrophysiological activity.

13. The method according to claim 1, wherein the indicator for the state of the conduction block includes one or more of a visual indicator for the state of the conduction block, an audible indicator for the state of the conduction block, and a tactile indicator for the state of the conduction block.

14. The method according to claim 1, further comprising the step of the computer outputting a confidence value of an indicator of the state of the conduction block.

15. The method according to claim 1, wherein the step of analyzing the sensed electrophysiological activity with respect to the induced response by the pacing signal includes the step of the computer analyzing the sensed electrophysiological activity with respect to signal amplitudes that exceed a preset noise level threshold.

16. The method according to claim 15, wherein the computer determines the preset noise level threshold in accordance with the amplitude of the electrophysiological activity sensed during the rest interval.

17. A system for evaluating conduction block across tissue damage, A pacing system configured to apply a pacing signal to the tissue on the first side of the injury, wherein the pacing signal includes a plurality of pacing pulses, A sensing system configured to sense electrophysiological activity within the tissue on the second side of the injury, wherein the second side of the injury is opposite to the first side of the injury, Conduction block signal processing device, Equipped with, The conduction block signal processing device is configured to analyze the electrophysiological activity detected by the pacing signal and output an indicator of the conduction block state. The indicator of the state of the aforementioned conduction block is, If a preset number of consecutive pacing pulses do not induce the aforementioned evoked response, this serves as an indicator that conduction block has been achieved. When the aforementioned preset number of consecutive pacing pulses induce the aforementioned evoked response, this serves as an indicator that there is no conduction block. Otherwise, including an indicator of the uncertain block state, system.

18. The system according to claim 17, wherein the pacing system, the sensing system, and the conduction block signal processing device are integrated into an electroanatomical mapping system.

19. The system further comprises a multi-electrode catheter operably coupled to both the pacing system and the sensing system, The aforementioned multi-electrode catheter is A plurality of first electrodes operably coupled to the pacing system to apply the pacing signal to the tissue on the first side of the injury, The sensing system comprises a plurality of second electrodes operably coupled to the second side of the injury, which sense the electrophysiological activity in the tissue. The system according to claim 17, wherein the first plurality of electrodes are located distal to the second plurality of electrodes on the multi-electrode catheter.

20. The pacing system according to claim 19, wherein the pacing system is configured to apply the pacing signal to the tissue using each electrode of the first plurality of electrodes simultaneously.

21. The system according to claim 17, wherein the conduction block signal processing device is further configured to determine the preset number of consecutive pacing pulses as a function of at least one of the intrinsic heart rate and the rate of the pacing signal.

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