Discrimination of supraventricular tachycardia in combined CCM-ICD devices

Abstract

During cardiac arrhythmia, defibrillation shocks from an implanted cardioverter-defibrillator are inhibited based on sensing of electrical wavefront arrival times indicative of supraventricular tachycardia resulting from the cardiac arrhythmia. In some embodiments, the arrival times of the electrical wavefront at at least two ventricular locations in the heart are sensed, one relatively superior and one relatively inferior (e.g., relatively superior and inferior locations on the ventricular septum). In some embodiments, delivery of a defibrillation shock is inhibited if the arrival time at the more inferior location is within a predetermined interval after arrival at the more superior location. In some embodiments, additional sensing of electrical wavefront arrival at one or more non-septal ventricular locations is performed, and inhibition of defibrillation shocks is optionally itself inhibited if the additional sensing indicates that the wavefront initiated at a ventricular location.

Description

[Technical field]

[0001] Related Applications This application claims priority to U.S. Provisional Patent Application No. 62 / 795,612, filed Jan. 23, 2019, the contents of which are incorporated herein by reference.

[0002] The present invention, in some embodiments thereof, relates to the field of implanted cardiac devices, and more particularly to the control of cardiac pacing using implanted cardiac devices. [Background technology]

[0003] The use of implantable cardioverter defibrillators (ICDs) is common in patients with chronic heart failure (CHF). ICDs significantly reduce mortality among these patients, and ICD therapy is recommended for primary prevention to reduce all-cause mortality by reducing sudden cardiac death (SCD) in CHF patients with a left ventricular ejection fraction (LVEF) less than 35%.

[0004] Mika et al., in U.S. Patent No. 6,263,242, "Device and Method for Timing Delivery of Non-Excitatory ETC Signals to the Heart," describe a CCM signal that is delivered to cardiac tissue when an intrinsic depolarization wave sweeping through the ventricle is detected within a specific timing relationship between two electrode sites. Summary of the Invention [Means for solving the problem]

[0005] According to some embodiments of the present disclosure, a method is provided for controlling an input to an implanted cardiac device in response to a cardiac arrhythmia, the method including: sensing a direction of an electrical wavefront passing through a ventricular region of the heart during a cardiac arrhythmia in the heart; and providing an input to the implanted cardiac device based on the sensed direction of the electrical wavefront.

[0006] In some embodiments, the implanted cardiac device is configured to apply an anti-arrhythmic therapy, and the implanted cardiac device is configured to apply the anti-arrhythmic therapy using the provided input.

[0007] In some embodiments, the implanted cardiac device includes a defibrillator and configuring the defibrillator to generate a defibrillation shock using the provided input.

[0008] In some embodiments, the ventricular region of the heart includes the ventricular septum.

[0009] According to some embodiments of the present disclosure, the sensing includes determining a direction of the electrical wavefront passage using the calibration information.

[0010] In some embodiments, the sensing includes sensing a relative timing of passage of the electrical wavefront through multiple locations within the ventricular region.

[0011] In some embodiments, each of the multiple locations is defined by the location of an electrode pair used to perform the sensing.

[0012] In some embodiments, the controlling includes preventing generation of a defibrillation shock when the sensed direction of the electrical wavefront passage indicates that the electrical wavefront is traveling in a direction from the atrium toward the ventricle.

[0013] In some embodiments, sensing the direction includes sensing times of electrical wavefront arrival at at least two ventricular locations in the heart, and the provided input is instructions to the implanted cardiac device to configure application of anti-arrhythmia therapy based on the relative timing of sensing at the at least two locations.

[0014] In some embodiments, the at least two locations include two locations along the interventricular septum.

[0015] In some embodiments, the at least two locations along the ventricular septum are at least 1 cm apart.

[0016] In some embodiments, the two locations along the ventricular septum are located along a superior-inferior axis extending along the ventricular septum.

[0017] In some embodiments, each of the at least two positions is defined by the position of an electrode pair.

[0018] In some embodiments, each electrode pair is disposed on a separate lead.

[0019] In some embodiments, multiple electrode pairs are disposed on a single lead.

[0020] In some embodiments, at least one electrode is used as a member of a plurality of electrode pairs.

[0021] In some embodiments, the implanted cardiac device is at least a dual function device.

[0022] In some embodiments, the implanted cardiac device includes a cardiac contractility modulation (CCM) therapy device.

[0023] In some embodiments, electrodes on the leads used for cardiac sensing and / or therapy current delivery for CCM therapy by the CCM therapy device are also used to sense electrical wavefront arrival at at least two locations.

[0024] In some embodiments, the direction of the electrical wavefront is from the atrium to the ventricle and the input is used to inhibit the delivery of anti-arrhythmic therapy.

[0025] In some embodiments, the at least two locations are at different locations along a superior-inferior axis, and provision is made to suppress the input when the electrical wavefront is sensed to arrive at the more superior location before arriving at the more inferior location.

[0026] In some embodiments, if the electrical wavefront arrives at the inferior location before a predetermined delay has elapsed since arriving at the superior location, delivery of the anti-arrhythmia therapy is not inhibited.

[0027] In some embodiments, the at least two locations include non-septal locations within the ventricle.

[0028] In some embodiments, the provided input acts to inhibit delivery of anti-arrhythmia therapy when the electrical wavefront is sensed to reach a more superior location within the ventricular septum before it reaches a more inferior location within the ventricular septum, unless the time of the electrical wavefront reaching a non-septal location within the ventricle is within a predetermined interval before the electrical wavefront is sensed to reach within the ventricular septum.

[0029] According to some embodiments of the present disclosure, an implantable cardioverter defibrillator device (ICD) is provided that is configured to sense electrical wavefront arrival times at at least two ventricular locations in the heart during a cardiac arrhythmia in the heart and within an interval between heartbeats, and to inhibit generation of a defibrillator shock in response to the cardiac arrhythmia based on the relative timing of the sensing at the at least two locations.

[0030] In some embodiments, the device includes at least two bipolar sensing electrodes.

[0031] In some embodiments, the at least two bipolar sensing electrodes are configured to be attached at locations along the interventricular septum.

[0032] In some embodiments, the at least two bipolar sensing electrodes are on separate leads.

[0033] In some embodiments, the device is also configured to perform cardiac contractility modulation (CCM) therapy using electrodes on a separate lead.

[0034] In some embodiments, the at least two bipolar sensing electrodes are on a single lead of the ICD.

[0035] In some embodiments, the single lead of the ICD is configured to be implanted extending along the interventricular septum.

[0036] In some embodiments, the at least two bipolar sensing electrodes are configured to be positioned at different locations along the superior-inferior axis within the ventricular septum, and the ICD inhibits generation of a defibrillation shock when the electrical wavefront is sensed to arrive at a more superior location before arriving at a more inferior location.

[0037] In some embodiments, the device includes a sensing electrode configured to be placed in a non-septal location in the ventricle.

[0038] In some embodiments, the device is configured such that if a sensing electrode configured for placement at a non-septal location in the ventricle senses the arrival of an electrical wavefront within a predetermined interval before the ICD senses the electrical wavefront arriving at the ventricular septal location, delivery of a defibrillation shock is not inhibited.

[0039] In accordance with aspects of some embodiments of the present disclosure, there is provided a method of controlling an input to an implanted cardiac device in response to a cardiac arrhythmia, the method including receiving an input from first and second electrodes implanted in a ventricular region of the heart, determining a direction of an electrical wavefront traveling between the first and second electrodes using calibration information, and providing an input to the implanted cardiac device based on the sensed direction of the electrical wavefront.

[0040] Unless otherwise defined, all technical and / or scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the art to which this disclosure applies. Although methods and materials similar or equivalent to those described herein can be used in carrying out or testing the embodiments of this disclosure, exemplary methods and / or materials are described below. In case of conflict, the patent specification, including definitions, shall prevail. Moreover, the materials, methods, and examples are illustrative only and are not necessarily intended to be limiting.

[0041] As will be appreciated by those skilled in the art, aspects of the present disclosure may be embodied as a system, a method, or a computer program product. Thus, aspects of the present disclosure may take the form of an entirely hardware embodiment, an entirely software embodiment (including firmware, resident software, microcode, etc.), or an embodiment combining software and hardware aspects, all of which may be generally referred to herein as a "circuit," "module," or "system" (e.g., a method may be implemented using "computer circuitry"). Furthermore, some embodiments of the present disclosure may take the form of a computer program product embodied in one or more computer readable mediums having computer readable program code embodied therein. Implementation of the methods and / or systems of some embodiments of the present disclosure may include performing and / or completing selected tasks manually, automatically, or a combination thereof. Furthermore, according to the actual instrumentation and equipment of some embodiments of the methods and / or systems of the present disclosure, some selected tasks may be implemented by hardware, software, or firmware, and / or a combination thereof, for example, using an operating system.

[0042] For example, hardware for performing selected tasks according to some embodiments of the present disclosure may be implemented as a chip or circuit. As software, selected tasks according to some embodiments of the present disclosure may be implemented as a number of software instructions executed by a computer using any suitable operating system. In some embodiments of the present disclosure, one or more tasks performed in the method and / or system are performed by a data processor (also referred to herein as a "digital processor" for data processors that operate using groups of digital bits), such as a computing platform for executing a number of instructions. Optionally, the data processor includes a volatile memory for storing instructions and / or data, and / or a non-volatile storage device, such as a magnetic hard disk and / or removable media, for storing instructions and / or data. Optionally, a network connection is provided as well. A display and / or user input devices, such as a keyboard and / or mouse, are also optionally provided. Any of these implementations are more generally referred to herein as an instance of a computer circuit.

[0043] In some embodiments of the present disclosure, any combination of one or more computer readable media may be utilized. The computer readable medium may be a computer readable signal medium or a computer readable storage medium. The computer readable storage medium may be, for example, but not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, device, or device, or any suitable combination of the foregoing. More specific examples (non-exhaustive list) of computer readable storage media include: electrical connections having one or more wires, portable computer diskettes, hard disks, random access memories, read only memories, erasable programmable read only memories, optical fibers, portable compact disk read only memories, optical storage devices, magnetic storage devices, or any suitable combination of the foregoing. In the context of this specification, a computer readable storage medium may be any tangible medium that contains or can store a program for use by or in connection with an instruction execution system, device, or device. A computer-readable storage medium may also contain or store information for use by such a program, such as, for example, data structured in a manner that is recorded by the computer-readable storage medium so that the computer program can access it, for example, as one or more tables, lists, arrays, data trees, and / or other data structures. Here, a computer-readable storage medium that records data in a retrievable form as groups of digital bits is also referred to as a digital memory. In the case of a computer-readable storage medium that is not inherently read-only and / or in a read-only state, it should be understood that the computer-readable storage medium is also optionally used as a computer-writeable storage medium in some embodiments.

[0044] Herein, a data processor is said to be "configured" to perform data processing operations as long as it is coupled to a computer-readable memory to receive instructions and / or data therefrom, process them, and / or store the processing results in the same or another computer-readable storage memory. The steps to be performed (optionally on the data) are specified by the instructions. The processing operations may additionally or alternatively be referred to by one or more other terms, such as comparing, estimating, determining, calculating, discriminating, associating, storing, analyzing, selecting, and / or transforming. For example, in an embodiment, a digital processor receives instructions and data from a digital memory, processes the data according to the instructions, and / or stores the processing results in the digital memory. In some embodiments, "providing" the processing results includes one or more of transmitting, storing, and / or presenting the processing results. Presenting optionally includes displaying on a display, sounding, printing on a printout, or otherwise providing the results in a form accessible to human sensory capabilities.

[0045] A computer-readable signal medium may include, for example, a propagated data signal in which computer-readable program code is embodied, either in baseband or as part of a carrier wave. Such a propagated signal may take any of a variety of forms, including, but not limited to, electromagnetic, optical, or any suitable combination thereof. A computer-readable signal medium is not a computer-readable storage medium, but may be any computer-readable medium that can communicate, propagate, or transport a program for use by or in connection with an instruction execution system, device, or device.

[0046] The program code embodied on the computer readable medium and / or data used thereby may be transmitted using any suitable medium, including but not limited to wireless, wired, fiber optic cable, RF, etc., or any suitable combination of the foregoing.

[0047] Computer program code for carrying out operations for some embodiments of the present disclosure can be written in any combination of one or more programming languages, including object-oriented programming languages ​​such as Java, Smalltalk, C++, and conventional procedural programming languages ​​such as the "C" programming language or similar programming languages. The program code may be executed on the user's computer, partially on the user's computer, as a standalone software package, partially on the user's computer, partially on a remote computer, or entirely on a remote computer or server. In the latter scenario, the remote computer may be connected to the user's computer via any type of network, including a local area network (LAN) or wide area network (WAN), or may be connected to an external computer (e.g., via the Internet using an Internet Service Provider).

[0048] Some embodiments of the present disclosure may be described below with reference to flowchart illustrations and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present disclosure. It should be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general purpose computer, special purpose computer, or other programmable data processing device to generate a machine such that the instructions executed by the processor of the computer or other programmable data processing device create means for implementing the functions / acts specified in one or more blocks of the flowchart illustrations and / or block diagrams.

[0049] These computer program instructions may also be stored on a computer-readable medium that can direct a computer, other programmable data processing device, or other device to function in a particular manner, such that the instructions stored on the computer-readable medium produce an article of manufacture that includes instructions that implement the functions / acts specified in one or more blocks of the flowcharts and / or block diagrams.

[0050] Computer program instructions may also be loaded into a computer, other programmable data processing device, or other device to generate a computer-implemented process such that a series of operational steps are executed on the computer, other programmable device, or other device such that the instructions executing on the computer or other programmable device provide a process for implementing the functions / operations specified in one or more blocks of the flowcharts and / or block diagrams. [Brief description of the drawings]

[0051] Some embodiments of the present disclosure are described herein, by way of example only, with reference to the accompanying drawings. Referring now specifically to the drawings in detail, it is emphasized that the particulars shown are by way of example and for purposes of illustrative discussion of the embodiments of the present disclosure. In this regard, the description made with the drawings will make apparent to those skilled in the art how the embodiments of the present disclosure may be practiced. [Figure 1A] 1 illustrates a schematic representation of a method for discriminating SVT-type arrhythmias that are clear candidates for defibrillation by an ICD device, according to some embodiments of the present disclosure. [Figure 1B] FIG. 1 is a block diagram that illustrates a schematic representation of an ICD device configured to discriminate SVT-type arrhythmias based on input from two ventricular electrode sets. [Figure 1C] 13A-13C are schematic diagrams illustrating a more specific method for discriminating SVT-type arrhythmias that are clear candidates for defibrillation by an ICD device, according to some embodiments of the present disclosure. [Figure 1D]FIG. 1 is a schematic diagram of an implantable pulse generator (IPG) connected to a heart via two bipolar leads fixed to the right ventricular septum, according to some embodiments of the present invention. [Diagram 2] 13A-13C are schematic representations of the operation of an IPG's "windowing" algorithm, in accordance with some embodiments of the present disclosure. [Figure 3A] 13A-13C are schematic diagrams illustrating discrimination between normally conducted beats and ventricular ectopic beats by a conduction velocity filter according to some embodiments of the present disclosure. [Figure 3B] 13A-13C are schematic diagrams illustrating discrimination between normally conducted beats and ventricular ectopic beats by a conduction velocity filter according to some embodiments of the present disclosure. [Figure 4] FIG. 1 is a block diagram that illustrates a schematic of an IPG configured to deliver both CCM and ICD therapy. [Figure 5A] 13A-13C are schematic diagrams illustrating discrimination of conduction patterns across the interventricular septum, according to some embodiments of the present disclosure. [Figure 5B] 13A-13C are schematic diagrams illustrating discrimination of conduction patterns across the interventricular septum, according to some embodiments of the present disclosure. [Figure 5C] 13A-13C are schematic diagrams illustrating discrimination of conduction patterns across the interventricular septum, according to some embodiments of the present disclosure. [Figure 5D] 13A-13C are schematic diagrams illustrating discrimination of conduction patterns across the interventricular septum, according to some embodiments of the present disclosure. [Figure 5E] 13A-13C are schematic diagrams illustrating three-sensor discrimination of conduction patterns across the interventricular septum, according to some embodiments of the present disclosure. [Figure 6] 1 is a flowchart depicting a method for selecting a discrimination window according to some embodiments of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0052] The present invention, in some embodiments thereof, relates to the field of implanted cardiac devices, and more particularly to the control of cardiac pacing using implanted cardiac devices.

[0053] [overview] An aspect of some embodiments of the present invention relates to distinguishing between types of arrhythmic heart rate patterns according to whether an implantable cardioverter defibrillator device (ICD) should or should not deliver a shock. In some embodiments, for example, ventricular tachycardia (VT) is preferably corrected by the action of the ICD, while supraventricular tachycardia (SVT) (or another pattern) is preferably not corrected.

[0054] Although ICDs are potentially life-saving, they can also be seriously intrusive to a patient's life when their shocks are administered in response to cardiac arrhythmias (arbitrary, or more specifically, tachyarrhythmias) that do not require immediate treatment; we refer to such shocks as "unnecessary shocks."

[0055] Clinical studies suggest that up to 13% of patients receiving ICDs may receive unnecessary shocks, potentially resulting in pain, anxiety, and other adverse effects on the patient's health and / or well-being. As shown in the table below, large-scale clinical trials with ICDs have shown that as many as 20-40% of total shocks are "unnecessary" because they are delivered to terminate symptomatic arrhythmias that are not life-threatening or severe. [Table 1]

[0056] It has been reported that nearly 80% of unnecessary shocks are caused by supraventricular tachycardia (SVT), a group of tachyarrhythmias that include atrial fibrillation (AF), atrial flutter, sinus tachycardia, atrial tachycardia, atrioventricular (AV) reentrant tachycardia, and AV nodal reentrant tachycardia (AVNRT). This is well documented, for example, in the results of the MADIT II study (Daubert et al., J Am Coll Cardiol,51(14),2008), in which shocks were found to be delivered unnecessarily by ICDs due to: [Table 2]

[0057] To reduce the incidence of unnecessary shocks, algorithms have been developed to facilitate discrimination and avoidance of unnecessary delivery of ICD shocks on SVT based on analysis of rhythm irregularities and other factors. However, some SVT types potentially occur with a 1:1 A-V relationship, thereby presenting potential diagnostic challenges when evaluated through rhythm-only analysis.

[0058] To improve discrimination between true ventricular tachycardia and supraventricular tachycardia based on rate stability criteria, some devices use signals sensed directly from the atrium, however this requires the implantation of an additional lead (an atrial pacing / sensing lead) or the use of a specialized "single-pass" lead with a floating atrial sensing electrode.

[0059] Single-chamber ICDs (ICDs connected to the heart via a single ventricular lead) have utilized morphological analysis of the intracardiac electrogram (IEGM) signal to help distinguish VT from SVT because the shape of the IEGM as it propagates through the normal ventricular conduction system and therefore originates at the AV node typically differs from the shape recorded when a ventricular beat originates within the ventricle.

[0060] However, morphological analysis increases the use of computational power that is potentially scarce in power-constrained implantable devices. Furthermore, morphology has typically been analyzed through near-field channels (bipolar sensing), which tend to show locally adequate conduction, which may mischaracterize conduction patterns that are abnormal for the ventricle as a whole.

[0061] The device can apply a morphology discriminator to channels with more widely spaced electrodes, which may overcome the near-field problem, but this has the drawback of noisy signals (e.g., disrupted by myoelectric potentials, movement, and electromagnetic interference), potentially limiting the ability to discriminate tachyarrhythmias by type, e.g., true VT vs. SVT.

[0062] A device configured to provide cardiac contractility modulation (CCM) therapy may provide multiple (e.g., two) leads that can be implanted in cardiac tissue (e.g., the septal wall) and configured to sense electrical signals propagating therethrough. In some embodiments, the leads are spaced apart (e.g., spaced apart by at least 1 cm, 2 cm, or another distance) along an axis substantially parallel to the direction of propagation of a cardiac conduction wavefront passing between the two leads.

[0063] In some embodiments of the present invention, the propagation time and / or propagation path of the depolarization wavefront is detected via multiple right ventricular septal leads commonly used in cardiac contractility modulation (CCM) therapy. In some embodiments, the leads are positioned along the superior-inferior axis (e.g., positioned at least 1 cm, 2 cm, or another distance apart). This axis, in some embodiments, corresponds to the axis along which supraventricularly initiated conduction normally travels as it passes through the septum.

[0064] Detection from multiple leads is analyzed to provide discrimination of tachyarrhythmia type, e.g., discriminating SVT from VT. Optionally, a device capable of providing CCM is also configured to act as an ICD to provide defibrillation therapy and / or to provide sensing and / or discrimination input to an ICD. In some embodiments, detection uses an event-triggered windowing algorithm that distinguishes whether wavefront events detected at different sensing locations during a tachyarrhythmia occur in an order and / or timing consistent with SVT or more likely to be indicative of ventricular tachycardia.

[0065] Potentially, this method prevents inappropriate and unnecessary shock therapy due to rapid SVT conduction by enabling discrimination and exclusion of SVT-type tachyarrhythmias as shock therapy triggers, and is optionally implemented with little increase in demand on the limited levels of power and / or computational resources typically available in devices capable of delivering CCM signals.

[0066] In some embodiments, detection of SVT is used to provide input that influences the application of therapy other than shock therapy appropriate for VT.

[0067] In this specification, the embodiments are described with respect to the example of controlling defibrillation shocks delivered by an ICD implantable cardiac device. However, it should be understood that wavefront directional electrode sensing may additionally or alternatively be used in configuring the application of antiarrhythmic therapy in other types of devices, such as atrial sensing atrial pacing (AA pacing), inhibitory conditioning, and / or cardioversion. Before describing at least one embodiment of the present disclosure in detail, it should be understood that the present disclosure is not necessarily limited to the details of the construction and arrangement of the components and / or methods described in the following description and / or illustrated in the drawings in its application. Features described in the present disclosure, including features of the present invention, are capable of other embodiments or can be practiced or carried out in various ways.

[0068] [How to distinguish SVT type arrhythmia] Reference is now made to FIG. 1A, which illustrates generally a method for discriminating between SVT-type arrhythmias among tachyarrhythmias that are clear candidates for defibrillation by an ICD device, according to some embodiments of the present disclosure.

[0069] The first block of the flow chart represents two, optionally sequential or parallel, sensing operations. In block 161, in some embodiments, ICD sensing is performed, which involves measuring signals from one or more cardiac-implanted leads to generate data potentially indicative of the occurrence of a cardiac arrhythmic event that is a potential candidate for triggering shock therapy.

[0070] At block 162, in some embodiments, sensing is performed to detect the direction of wavefront propagation through the ventricular region. Optionally, the direction of wavefront propagation is determined from sensed relative timing of cardiac electrical activity waveforms arriving at multiple electrodes at different times, for example as described in connection with FIGS. 1C-1D, 2, and / or 5A-5D herein. Different relative timing of detection corresponds to potentially different directions. Directional analysis is optionally performed not to a precise direction, but rather sufficient to categorize the event at block 164. For example, the direction may simply be detected as including (such as an SVT event) or not including (such as a VT event) a clear superior-to-inferior component.

[0071] Furthermore, the direction determination itself is not necessarily performed as an explicit step and does not necessarily include providing a separate "directionality" output. For example, the timing difference indicated from the sensing in block 162 is optionally used to directly determine the categorization of SVT or VT in block 164. Nevertheless, the direction determination is implicit in this categorization since the basis for the timing difference indicating SVT or VT is because there are different directions of wavefront propagation for these two categories. Thus, part of the direction determination in block 162 is optionally performed as part of block 164, e.g., as part of the SVT / VT categorization itself.

[0072] In block 166, in some embodiments, categorization of the sensing in block 161 and / or the wavefront direction detection in block 164 occurs. The result of the categorization is an analysis of the wavefront directionality to determine the presence or absence of a cardiac arrhythmia and further infer whether the cardiac arrhythmia is of supraventricular origin or not, i.e., due to supraventricular tachycardia (SVT) or not.

[0073] In particular, the presence of a cardiac arrhythmia (cardiac arrhythmic event) may be detected as a severe tachycardia in the ventricle, which corresponds to a heart rate of, for example, 160 bpm, 170 bpm, 180 bpm, 190 bpm, and / or 200 bpm or more. Optionally, the heart rate window for shock therapy trigger is also below a higher heart rate, for example, a candidate ventricular arrhythmia is below 250 bpm. Ventricular arrhythmias at higher heart rates are optionally considered to be ventricular fibrillation and treated differently.

[0074] Optionally, if there are no current tachyarrhythmias that are candidate events for discriminating between SVT and VT arrhythmia types, the directional analysis is skipped in block 164. Optionally, block 162 is only performed to enable directional and / or timing analysis in the presence of current tachyarrhythmias.

[0075] In block 166, the flowchart branches depending on whether there is a detected arrhythmia that is not an SVT arrhythmia. If so, one or more defibrillation shocks are delivered in block 168. If not, no defibrillation shock occurs. In either case, the flowchart returns to sense / detect in blocks 161, 162.

[0076] 1C, which illustrates generally a more specific method for discriminating SVT-type arrhythmias that are clear candidates for defibrillation by an ICD device, according to some embodiments of the present disclosure. The method of FIG. 1C can be understood as illustrating a particular embodiment for implementing the method of FIG. 1A, and involves, for example, two corresponding operations, as described below.

[0077] The first block of the flowchart is presented with two parallel processing streams. Along one processing stream, at block 151, in some embodiments, ICD sensing is performed. This includes measuring signals from one or more leads implanted in the heart to generate data potentially indicative that a cardiac arrhythmia event is occurring. In some embodiments, block 151 corresponds to block 161 of FIG. 1A. At block 153, in some embodiments, the ICD sensing data is categorized as indicative of or not indicative of a cardiac arrhythmia (e.g., as described in connection with block 161), and at block 155, a determination is made as to whether the cardiac arrhythmia represents a candidate condition for defibrillation. In some embodiments, blocks 153, 155 may be understood to include some of the operations described in connection with block 164 of FIG. 1A.

[0078] Along another processing stream, in block 150, in some embodiments, a first event A is detected from a first ventricular electrode set (e.g., multiple electrodes arranged to perform near-field sensing). In block 154, in some embodiments, a second event B is detected from a second ventricular electrode set. As used herein, the term "near-field sensing" refers to sensing governed by an electric field gradient located at the electrodes of an electrode set and extending through a region between the electrodes of the electrode set. In some embodiments, the operations of blocks 150, 154 correspond to the operations of block 162 of FIG. 1A.

[0079] Detection of the relative timing of wavefront events at two different locations (e.g., by two different ventricular electrode sets) is used in some embodiments in estimating the direction of wavefront movement between the two locations. In a simple form, the estimated wavefront movement direction is "from" the earliest detection location "to" the later detection location. The wavefront can move at an oblique or perpendicular angle to the joint axis drawn between the two locations, in which case the wavefront movement direction can be optionally estimated by their relative timing. For example, if corresponding events are measured simultaneously at two locations, the wavefront is optionally estimated to be moving in a direction perpendicular to their joint axis. In some embodiments, the wavefront movement direction is constrained to a set of directions that are consistent with both physiologically plausible wavefront velocities and the relative timing of wavefront-related events measured at the two locations. Optionally, more than two sensing locations are used, which helps to further refine the estimate of the direction of wavefront propagation.

[0080] At least the first and second ventricular electrode sets are "ventricular" insofar as they are positioned within the ventricle to sense the electrical impulses (also referred to herein as "depolarization wavefronts") that control cardiac contraction where these electrical impulses propagate through the ventricular heart wall region. In some embodiments, the first and second ventricular electrode sets are more specifically implanted in the heart, e.g., in the septal wall of the heart, such that they perform sensing of localized signals within the ventricular septum at two respective distinct locations.

[0081] Optionally, the ventricular electrode sets overlap in their member electrodes, e.g., a central electrode is optionally shared between each of the two electrode sets. For purposes of illustration, the methods and systems herein are described with respect to two ventricular electrode sets, but it should be understood that three or more ventricular electrode sets are optionally used. Optionally, the ventricular electrode sets are on two different leads, or on three or more leads. A two-lead configuration is particularly relevant in some embodiments of the invention to providing SVT discrimination capabilities to certain devices jointly configured for both cardiac contractility modulation (CCM) therapy and operation as an ICD device. This is further described, for example, in connection with FIGS. 1D-4 herein. The sensing electrodes (of the electrode sets) optionally include electrodes that are also used for application of therapy, e.g., CCM therapy. In some embodiments, one or both of the ventricular electrode sets (or another electrode set using one or more electrodes from the first and second ventricular electrode sets) are also used in the ICD sensing of block 151.

[0082] Optionally, one lead (eg, a lead positioned to extend along the superior-inferior axis of the ventricular septum) comprises a ventricular electrode set.

[0083] Two electrodes can establish a bipolar configuration to provide near-field sensing, although optionally, more than two sensing electrodes are used in a near-field sensing configuration. As used herein, the term "bipolar" is used to denote an electrode set that includes at least two sensing electrodes.

[0084] As will be further described, for example, in connection with block 156, differences (e.g., timing differences) in electrical signals at multiple ventricular heart wall regions are analyzed to determine information regarding the nature of potential arrhythmias. In some embodiments, the ventricular locations are separated by approximately 1 cm, 1.5 cm, 2 cm, 2.5 cm, 3 cm, or another distance. Assuming an event detection order A then B (block 150, then block 154), the identity of the "first" and "second" bipolar configurations may differ depending on the direction of depolarization wavefront propagation (e.g., antegrade or retrograde propagation through the ventricular septum).

[0085] The decision of block 155 is made based on the ICD sensed data categorization in block 153. There are several different ways to perform this categorization, however these methods potentially include categorizing SVT arrhythmias as candidates for defibrillation, although these methods may be inappropriate.

[0086] If the detected cardiac arrhythmia (based on the ICD sensing data) is not a candidate condition for defibrillation, the flow chart returns to the start and ICD sensing and event detection 150, 154 at block 151 resumes.

[0087] If the detected cardiac arrhythmia is a candidate for defibrillation, the flowchart proceeds to block 156. In block 156, an analysis of events A and B is performed to determine whether the candidate arrhythmia is in fact suitable for defibrillation by categorizing it as a supraventricular tachycardia (SVT) arrhythmia or not.

[0088] In general, the relative timing of sensing of events A and B may be interpreted as indicating the direction and velocity of depolarization wavefront passage between the locations of the first and second electrode sets. The wavefront (or rather, at least the directional component of the wavefront) passes in a direction between the earlier and later sensing electrode locations at a velocity indicated by the ratio of their distance and their relative delay. Based on this indicated direction and velocity, ejection may be interpreted as initiating from the atrium (i.e., indicative of SVT) or from the ventricle. Examples of algorithms for performing the categorization are described, for example, in connection with Figures 5A-5E herein.

[0089] In some embodiments, the decisions at blocks 155, 156 are part of the actions of blocks 164 and / or 166 of FIG. 1A.

[0090] It should be understood that the categorization of the direction and rate of events A and B in block 156 does not necessarily follow a determination in block 155 of the arrhythmia as a candidate for defibrillation. The order shown in FIG. 1A is for purposes of illustration. It should also be understood that the two processing streams are optionally interconnected in other ways than as shown in FIG. 1A but lead to the same results. For example, the determination of block 156 is optionally used to inhibit ICD sensing and / or categorization, effectively leading to inhibition of defibrillation shock delivery before any ICD candidates (block 155) can be determined.

[0091] If the determination at block 156 does not indicate that events A, B are indicative of SVT as a category of arrhythmia, then at least one defibrillation shock is delivered to the heart at block 158 (which in some embodiments corresponds to block 168 of FIG. 1A). If so, defibrillation is discontinued. In either case, the flow chart returns to the beginning again.

[0092] [SVT type arrhythmia discrimination device] Reference is now made to FIG. 1B, which is a block diagram that generally illustrates an ICD device configured to discriminate SVT-type arrhythmias based on input from two ventricular electrode sets 103, 105.

[0093] Block 174 represents a detector configured to detect arrhythmias (e.g., corresponding to the operations of blocks 151, 153, 155 of FIG. 1C) that are candidates for correction by administration of a defibrillation shock by defibrillation circuitry 176. The sensed data used to perform this detection optionally comes from one or both of ventricular electrode sets 103, 105. Block 172 represents an SVT discriminator configured to perform the operations of blocks 150, 154, and 156 of FIG. 1C.

[0094] In some embodiments, the ICD device 170 is a dual or multi-function device, such as a device that combines ICD and CCM therapy; a device that combines ICD and cardiac resynchronization therapy (CRT); an ICD device combined with another device, such as a vagus nerve, baroreceptor, or other neurostimulator; or another implantable cardiac device. In some embodiments, three or more functions (e.g., selected from the listed functions) are combined. A combined ICD / CCM therapy device is described in relation to FIG. 4.

[0095] [Implantable pulse generator] Reference is now made to Figure 1D, which illustrates generally an implantable pulse generator (IPG) 100 connected to the heart via two bipolar leads 102, 104 fixed to the right ventricular septum, in accordance with some embodiments of the present invention. The principles of operation of this device serve as background for explaining features (presented in connection with Figure 4) that provide a modified version of the IPG 100 with an SVT discriminating ICD.

[0096] The IPG 100 is an example of a device configured for non-ICD functions, such as delivery of CCM therapy. The illustrated IPG 100 optionally represents, for example, an Impulse Dynamics OPTIMIZER SMART Implantable Pulse Generator (IPG) for delivery of CCM therapy. The OPTIMIZER SMART IPG continuously monitors the heart's intrinsic activity and generates CCM signals in synchronization with sensed local electrical activity, such that their delivery occurs during the ventricular absolute refractory period.

[0097] The OPTIMIZER SMART IPG incorporates two ventricular sense amplifiers 102A, 104A that detect ventricular activation from the IEGM picked up by ventricular leads 102, 104 attached to the right ventricular septum 50 of the heart (at locations 103 and 105, respectively). Optionally, the leads 102, 104 are separated by at least 1 cm, 2 cm, 3 cm, 4 cm, or another distance. The sensed and amplified ventricular activation signals are transmitted to a controller 112. Optionally, one or more additional leads 120 are connected to other locations on the heart 50, for example, at an atrial location.

[0098] Optionally, amplifier 120A transmits the sensed and amplified excitation signal to controller 112. Controller 112 is configured to operate CCM generator 110 to generate a return signal via leads 102, 104 to affect cardiac contraction, for example, as described herein in connection with Figures 2-3B.

[0099] Also shown is battery recharging and power conditioning circuitry 116 , including a rechargeable cell 117 (optionally a lithium-ion cell) and a receiver coil 118 ; and inductive communication and telemetry circuitry 114 .

[0100] Reference is now made to FIG. 2, which illustrates generally the operation of the IPG 100 "windowing" algorithm, in accordance with some embodiments of the present disclosure.

[0101] In some embodiments, a control algorithm of the IPG 100 implemented by the controller 116 enables delivery of a CCM signal to the heart at a certain heart beat via the CCM generator 110 if proper intraventricular activation sequence and timing is detected between the ventricular-septal IEGM signals sensed via the leads 102, 104.

[0102] The trace 200 represents events corresponding to cardiac cycles that are not categorized as abnormal (e.g., not subject to excessive noise or ventricular tachycardia). Upon sensing a ventricular event V (e.g., the onset of a Q wave and / or an R wave as measured by the lead 102), the controller 116 opens a local sensing alarm window 204 after an optional initial delay 202.

[0103] The warning window can be inside the AV interval (between P and R), inside the VA interval (outside the AV interval), or partially inside the AV and partially inside the VA interval. For example, the location in time 204 of the warning window, in some embodiments, is determined by two programmable parameters: Alarm onset: Begins with a right ventricular event V (e.g., detected by lead 102) Length of delay 202 Alert Width: Duration of the alert window 204

[0104] In some embodiments, the first local sensed event detected within the warning window 204 acts as a trigger for a potential CCM signaling (e.g., with LS representing the time of the local sensed event sensed by the lead 104). Once an event is detected, the warning window 204 is immediately ended.

[0105] From this moment on in the cardiac cycle, valid locally sensed events detected by the lead 104 but outside the alarm window are considered to be premature ventricular contractions (PVCs). These optionally inhibit CCM signaling, for example, for a programmable number of cycles.

[0106] If not inhibited, CCM transmission occurs during a period 208, optionally after a post-sensing delay 206.

[0107] A "windowing" algorithm using the two bipolar leads 102, 104 effectively performs a conduction velocity filter, whereby only beats whose depolarization wavefront propagates in a certain direction and at a certain velocity qualify such beats as being suitable for delivery of a CCM signal.

[0108] 3A-3B, which diagrammatically illustrate discrimination by a conduction velocity filter between normally conducted beats and ventricular ectopic beats according to some embodiments of the present disclosure. In some embodiments, discrimination is used to deliver a CCM signal only on normally conducted beats. FIG. 3A illustrates the state of a normally conducted beat in a heart 50. The beat initiates at the sinoatrial (SA) node 53, travels via an atrial conduction pathway 54 to the atrioventricular (AV) node 51, and then propagates from the AV node 51 along a ventricular conduction pathway 52. ​​A trace 300 illustrates landmark electrical events during a cardiac cycle, with an initial delay 200, an alarm window 204, a post-sense delay 206, and a CCM delivery period 208 shown as described in connection with FIG. 2.

[0109] 3B illustrates one type of potential arrhythmia, involving ectopic ventricular pulse initiation from region 56 along ventricular conduction pathway 57, and disorganized atrial conduction along arterial conduction pathway 59. This type of arrhythmia is a potential candidate for correction by administration of a defibrillation shock, for example, using a dual CCM / ICD device as described herein in connection with FIG.

[0110]

[0023] Referring now to Figure 4, Figure 4 generally illustrates a block diagram of an IPG 400 configured to deliver both CCM and ICD therapy. The IPG 400 further performs SVT vs. VT discrimination based on an analysis of the propagation time and propagation path of the depolarization wavefront, according to some embodiments of the present disclosure. Potentially, SVT vs. VT discrimination helps reduce the incidence of unnecessary shocks.

[0111] In some embodiments, two electrogram signals are sensed from a bipolar electrode pair in a CCM lead 102 (optionally equivalent to lead 102 in FIG. 1D) and an ICD lead 104 (optionally equivalent to lead 104 in FIG. 1D). These signals are amplified and detected by sense amplifiers 102A, 104A. These amplifiers have sufficient timing resolution to measure the different wavefront arrival times at the bipolar electrode locations 103, 105. Optionally, this is achieved by using a relatively high frequency band (e.g., 70-200 Hz). The measurement rate and inter-channel timing and sequence are used by a CCM controller 112 to control a CCM generator 110 to deliver CCM signals (e.g., to the right ventricular septum) via the same electrodes of the leads, for example, as described in FIGS. 2-3B.

[0112] In some embodiments, a separate ICD sense amplifier 402A, optionally having a bandpass similar to that of conventional ICD devices (e.g., in the range of 8-40 Hz), detects intracardiac events that are used by prior art ICD algorithms executed within ICD controller 405 to detect tachyarrhythmias. However, prior to defibrillation, the method of FIG. 1A is used to evaluate whether the tachyarrhythmia is the result of rapid supraventricular activity (non-shockable) or a reentrant loop within the ventricle (which should be treated with a shock).

[0113] To perform the discrimination, the wavefront conduction velocity (the direction and speed of the propagating depolarization wavefront) measured from the IEGMs picked up by the two bipolar pairs and analyzed by the CCM controller 112 is communicated to the ICD controller 405, for example, on a beat-by-beat basis.

[0114] 4 also shows an optional pacing pulse generator 409 and a defibrillation pulse generator 407 with a defibrillation capacitor 408 configured to charge with energy (e.g., about 36 J of energy) prior to delivery of a defibrillation shock. Other circuitry of the IPG 400, in some embodiments, includes a defibrillation battery 410 and battery management circuitry 411, rechargeable cell 117, charging / power conditioning circuitry 116, and receiver / communication coil 118, and high voltage isolation circuitry 403. Housekeeping circuitry 420 manages functions such as an inductive charger / communication circuitry 422, a magnetic sensor 424, and / or a temperature sensor 426.

[0115] [Distinguishing conductive patterns] Reference is now made to FIGS. 5A-5D, which diagrammatically illustrate discrimination of conduction patterns across the interventricular septum, in accordance with some embodiments of the present disclosure.

[0116] 5A-5D each show leads 102, 104 and sensing (electrode) locations 511A, 512A positioned in the septum of heart 50. Also shown are different estimates of the intraseptal conduction vector 515, which varies in direction and length depending on the apparent direction and velocity of wavefront conduction between sensing locations 511A and 512A.

[0117] 5A-5D, marks 511, 512 represent the times when the conducted wavefront reaches sensing locations 511A and 512A, respectively. In some embodiments, time range 513 represents a discrimination window used to distinguish a particular supraventricular tachycardia from a true ventricular tachycardia.

[0118] In some embodiments of the invention, the first division of normal and abnormal sinus rhythm may involve orthogonal conduction (eg, Figures 5A, 5C) and retrograde conduction (eg, Figures 5B, 5D) through the interventricular septum.

[0119] In particular, normal sinus rhythm through the septum as shown in FIG. 5A, as well as following SVT, are conducted through the normal conduction devices (the His and Purkinje bundles) in the interventricular septum to the ventricles in the normal direction (i.e., conduction vector 515 from wavefront location 510A to wavefront location 510B). Atrial tachycardia atrial flutter Atrial fibrillation Atrioventricular Nodal Reentrant Tachycardia (AVNRT) Orthodromic Wolf-Parkinson-White Atrioventricular Reentrant Tachycardia (Orthodromic WPW-AVRT)

[0120] True ventricular tachycardias, on the other hand, are conducted through the conduction system in a retrograde direction and / or result in disorders within the conduction system itself. For example, in FIG. 5B, conduction is retrograde from wavefront location 510C to wavefront location 510D. In FIG. 5D, conduction includes a retrograde component as the wavefront travels between wavefront location 510H and wavefront location 510G. Conduction in FIG. 5C is forward, but travels from wavefront location 510E to wavefront location 510F and does not originate supraventricularly.

[0121] In some embodiments, shock delivery for rhythms categorized as tachycardias by conventional ICD algorithms is inhibited (or at least delayed) whenever the intraseptal conduction velocity and / or conduction direction reported by the CCM controller 112 demonstrates that orthogonal conduction direction and velocity fall within a predetermined range. This potentially reduces the incidence of unnecessary shocks delivered to patients for the majority of SVTs.

[0122] The timelines of Figures 5A-5D represent examples of how this may be implemented in some embodiments of the invention. In each of Figures 5A-5D, the mark 511 falls either within the discrimination window 513 (Figure 5A) or outside the discrimination window 513 (Figures 5B-5D). In some embodiments, the discrimination window 513 has a predetermined duration and a predetermined start delay from detection of the mark 512. Optionally, the start and / or duration parameters of the discrimination window 513 are controlled by a predetermined constant. Optionally, the start and / or duration parameters of the discrimination window 513 are determined as described in connection with Figure 6. In some embodiments, the discrimination window 513 starts after wavefront detection at the sensing location 512A, for example, between about 0-100 ms. In some embodiments, the start is between about 0-50 ms. In some embodiments, the discrimination window 513 closes between about 1-75 ms after start. In some embodiments, the discrimination window 513 closes between about 1-40 ms after start. It should be appreciated that the periods before and / or after the discrimination window 513 are themselves optionally distinguished from one another and optionally subdivided to allow for discriminating between different wavefront origins, e.g., as shown and / or described in connection with Figures 5A-5D. Optionally, input is provided to a therapy device in addition to and / or instead of a shock defibrillator, e.g., to regulate the delivery of pacing and / or inhibitory electrical pulses.

[0123] Optionally, these parameters are adjusted depending on, for example, the recent heart rate, the duration of the tachycardia, or another parameter. For example, a condition for successful ICD delivery may be that the cardiac rhythm frequency is within a particular range. Additionally, SVT detection parameters may be adjusted for different ranges of cardiac rhythm frequency. For example, in the normal sinus rhythm rate zone (e.g., about 60-160 bpm), the device is optionally disabled from delivering ICD therapy. In the range associated with potential ventricular tachycardia (e.g., about 160-240 bpm), a windowing algorithm may be optionally activated with a window wide enough that the device errs more on the side of preventing therapy (possibly delivering a shock after anti-tachycardia pacing attempts) than in the case of fast ventricular tachycardia. In the range associated with fast ventricular tachycardia (e.g., 240-300 bpm), the inhibition window is optionally programmed to be narrower (shorter in milliseconds and as a percentage of cardiac cycle length). Above 300 bpm, the windowed discrimination algorithm is optionally not used to determine if an ICD should be delivered.

[0124] If mark 511 falls within discrimination window 513, in some embodiments this is considered an indication that the tachycardia is supraventricular in origin and ventricular defibrillation is inhibited.

[0125] The in-window / out-of-window results determining the SVT origin of the arrhythmia are optionally applied to inhibit defibrillation in various ways. In some embodiments, operation of the ICD algorithm is prevented by the discrimination of SVT. In some embodiments, the ICD algorithm operates independently, but any decision by the algorithm to initiate defibrillation is ignored in the case of SVT. Optionally, the ICD algorithm itself is modified to perform the SVT decision and modify its output accordingly. Optionally, the SVT decision is triggered only when it is determined that the arrhythmia has already begun, e.g., when triggered by the results of the ICD algorithm and / or when triggered by an earlier pattern of sensed data that matches the initiation and / or progression pattern of the arrhythmia. Optionally, detection of SVT is used to trigger a non-defibrillation therapy. Optionally, inhibition of defibrillation following determination of the SVT origin of the arrhythmia is itself inhibited by further inputs, e.g., time- and / or heart rate-dependent inputs.

[0126] The windowing algorithm is described herein for illustrative purposes. It has the potential advantage of being computable with minimal computational resources and / or implemented by analog timing circuitry. The same defibrillation inhibition results can be obtained in other ways. For example, in some embodiments, the apparent velocity and direction of the conduction vector 515 is explicitly determined, and a conduction vector that falls within certain parameters of its velocity and direction is considered to be indicative of any current arrhythmia being due to SVT.

[0127] Reference is now made to FIG. 5E, which illustrates generally three-sensor discrimination of conduction patterns across the interventricular septum, in accordance with some embodiments of the present disclosure.

[0128] The remaining two forms of arrhythmia, namely retrograde Wolf-Parkinson-White atrioventricular reentrant tachycardia (retrograde WPW-AVRT) and Wolf-Parkinson-White atrial fibrillation (WPW-AF), comprise SVT that is potentially indistinguishable from true ventricular tachycardia through analysis of the conduction velocity and direction of the depolarization wavefront that sweeps only the interventricular septum.

[0129] In addition to the leads 102, 104 located in the septum of the heart 50, FIG. 5E shows a third lead 103 located in another ventricular region. The lead 103 is shown entering the heart 50 through the same vessel (e.g., the superior vena cava) as the leads 104, 102, but optionally from another direction. The sensing (electrode) locations 511A, 512A are thereby supplemented with a third sensing location 514A corresponding to the location of the electrode on the lead 103. In some embodiments, the lead 103 is an LV lead, such as those used in cardiac resynchronization therapy (RCT), e.g., a lead that runs along the coronary sinus. In some embodiments, the lead 103 is a lead located at the apex of the left atrium.

[0130] In this case, the estimate of the intraseptal conduction vector 515 appears indistinguishable from normal forward conduction, and in fact, the mark 511 on the timeline of FIG. 5E falls within the discrimination window 513. This could potentially result in a determination that any simultaneous tachycardia is of supraventricular origin.

[0131] However, in some embodiments, detection of a conducted wavefront passing through sensing location 514A results in activation of a predetermined inhibition window 513B that inhibits the defibrillation discrimination function of discrimination window 513, such that defibrillation is not inhibited even if mark 511 falls within a time period that would result in prevention of delivery of a defibrillation shock.

[0132] Inhibition window 513B, in some embodiments, is long enough to cover the time it takes for conduction to make a circuitous pass between wavefront location 510J and wavefront location 510K, but not so long (e.g., about 100-250 ms, or another suitable duration) to potentially inhibit discrimination of SVT. Optionally, inhibition window 513B begins after delay 513A (e.g., about 1-50 ms). In some embodiments, delay 513A is set long enough so that a wavefront of atrial origin, e.g., arriving first at sensing location 514A and then several milliseconds later at, e.g., sensing location 512A, is not confused with a ventricular origin of wavefront initiation. In some embodiments, inhibition window 513B may itself be inhibited, e.g., if there is detection of a conduction wavefront passing sensing location 512A immediately before or within a sufficiently short period of time after the wavefront passes location 515A.

[0133] Reference is now made to Figure 6, which is a flow chart depicting a method for selecting a discrimination window 513 according to some embodiments of the present disclosure. For example, as described in connection with Figures 5A-5E, a relative delay between a first electrode and a second electrode that falls within the discrimination window 513 is optionally classified as indicative of a supraventricular (e.g., atrial) origin of the impulse that triggers the heartbeat. If the heartbeat occurs during a period of tachyarrhythmia, this indication is optionally used to distinguish between SVT and VT.

[0134] At block 610, in some embodiments, multiple electrodes are placed on the cardiac septal wall, for example, as illustrated and / or discussed in connection with FIG. 1D and / or FIG. 5A-5E. The exact placement of the electrodes, optionally including their relative placement (superior or inferior to one another), need not necessarily be completely known prior to their implantation. Furthermore, the electrical conductivity of the electrical activity wavefront between the locations of the electrodes need not necessarily be completely known prior to their implantation. Thus, in some embodiments, the optimal positioning of the discrimination window 513 is determined based on measurements made to be indicative of the actual electrode configuration after implantation.

[0135] In block 612, in some embodiments, the relative delay of the cardiac electrical activity wavefront arriving at the multiple electrodes is measured. This can be performed in different ways. Optionally, the relative time of arrival of the R-wave component of the cardiac ECG is measured at each of the multiple electrodes. The R-wave component has potential advantages in this use insofar as it is relatively large in amplitude and relatively fast, but any other component of the ongoing circulating cardiac electrical activity waveform is used in addition to or instead of the R-wave. The relative delay is measured for electrical impulses having an atrial origin, e.g., origin from normal AV node activation, atrial paced activation, or another atrial origin. The relative wavefront delay of the normal heart rate is optionally considered to represent the relative wavefront delay that will also occur during a presumed future episode of SVT. Additionally or alternatively, the atrial paced activation is repeated at a rate that simulates SVT.

[0136] The relative arrival times can be measured any suitable number of times, for example, to allow for the calculation of a statistical representation of the normal relative times of waveform arrival at the electrode implantation site. Optionally, the statistical representation includes the average delay and the standard deviation of that delay. Optionally, the relative delay measurements are performed at multiple heart rates. The information obtained from these measurements is also referred to herein as calibration information. For example, the calibration information indicates the direction of the electrical wavefront from the atrium to the ventricle when the electrical wavefront arrives at the second electrode after arriving at the first electrode, which delay is also characteristic of the delay from the first electrode to the second electrode of the wavefront known from the measurements of block 612 to be operated on the atrium.

[0137] At block 614, in some embodiments, a discrimination window is selected based on the wavefront delay measurements (calibration information) of block 612. In some embodiments (e.g., for a typical Gaussian distribution of relative delays), the window is selected as a range of delays within ±2, ±3, ±4, or another number of standard deviations of the mean delay. Optionally, the window size and offset are selected to include all measurements of relative arrival times, or at least a majority of the measurements, e.g., at least 99% of the measurements, or at least 99.9% of the measurements. Optionally, the selected discrimination window is dynamic and heart rate dependent and / or selected according to the current heart rate, e.g., to account for potential differences in wavefront velocity as a function of heart rate. Heart rate adjustment of the window is optionally performed based on measurements of delays at different heart rates (e.g., as described in connection with block 612). Optionally, heart rate adjustment of the window is performed based on a norm derived from observations of a patient population.

[0138] Thus, delays measured after falling within this range are likely to be indicative of an electrical wavefront originating from the atrium. In some embodiments, this delay range is used to set a discrimination window 513, for example, as described in connection with Figures 5A-5E. In some embodiments, whether a delay falls within the discrimination window 513 is used to set an input to an implanted cardiac device, for example, an input to inhibit the delivery of a defibrillation shock therapy.

[0139] [General] When used herein in reference to an amount or numerical value, the term "about" means "within ±10%."

[0140] The terms "comprises," "comprising," "includes," "including," "having" and conjugations thereof mean "including but not limited to."

[0141] The term "consisting of" means "including and limited to."

[0142] The term "consisting essentially of" means that a composition, method, or structure may include additional ingredients, steps, and / or moieties, provided that the additional ingredients, steps, and / or moieties do not materially alter the basic and novel characteristics of the claimed composition, method, or structure.

[0143] As used herein, the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise. For example, the term "a compound" or "at least one compound" can include a plurality of compounds, including mixtures thereof.

[0144] The words "example" and "exemplary" are used herein to mean "serving as an example, instance, or illustration," and any embodiment described as "example" or "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments and / or to exclude the incorporation of features from other embodiments.

[0145] The term "optional" is used herein to mean "provided in some embodiments and not provided in other embodiments," and any particular embodiment of the present disclosure may include multiple "optional" features, except to the extent such features are inconsistent.

[0146] The term "method" as used herein refers to methods, means, techniques, and procedures for accomplishing a given task, including, but not limited to, methods, means, techniques, and procedures known or readily developed from known methods, means, techniques, and procedures by practitioners in the fields of chemistry, pharmacology, biology, biochemistry, and medicine.

[0147] As used herein, the term "treating" includes eliminating, substantially inhibiting, slowing, or reversing the progression of a condition, substantially ameliorating the clinical or cosmetic symptoms of a condition, or substantially preventing the appearance of clinical or cosmetic symptoms of a condition.

[0148] Throughout this application, various embodiments of the invention may be presented in a range format. It should be understood that the description in range format is merely for convenience and brevity, and is not an inflexible limitation of the scope of the invention. Thus, the description of a range should be considered to specifically disclose all of the possible subranges, as well as each individual numerical value within that range. For example, the description of a range such as 1 to 6 is intended to specifically disclose not only the subranges 1 to 3, 1 to 4, 1 to 5, 2 to 4, 2 to 6, 3 to 6, etc., but also each individual numerical value within that range, e.g., 1, 2, 3, 4, 5, and 6. This applies regardless of the magnitude of the range.

[0149] Whenever a numerical range is given herein (e.g., "10-15," "10to15," or any pair of numbers joined by these or another such range designations), it is meant to include any number (fractional or integer) within the indicated range limit, including the range limit, unless the context clearly indicates otherwise. The terms "range / ranging / ranging between" a first indicated number and a second indicated number, "range / ranging from" a first indicated number, "to," "up to," "until," or "through" (or other "range-indicating"-like terminology) a second indicated number, are used interchangeably herein and are meant to include the first and second indicated numbers, and all decimals and integers therebetween.

[0150] While the present invention has been described in conjunction with specific embodiments thereof, many alternatives, modifications, and variations will be apparent to those skilled in the art. Accordingly, it is intended to embrace all such alternatives, modifications, and variations that fall within the spirit and broad scope of the appended claims.

[0151] All publications, patents, and patent applications mentioned in this specification are incorporated herein by reference in their entirety to the same extent as if each individual publication, patent, and patent application was specifically and individually incorporated herein by reference. In addition, citation or identification of any reference in this application should not be construed as an admission that such reference is available as prior art to the present invention. Nor should it be necessarily construed as limiting, to the extent that section headings are used.

[0152] It will be understood that, for clarity, certain features that are described in this disclosure in the context of separate embodiments may also be provided in combination in a single embodiment. Conversely, for brevity, various features that are described in the context of a single embodiment may also be provided separately or in any suitable subcombination, or as appropriate, in any other described embodiment of the disclosure. Certain features described in the context of various embodiments are not to be considered essential features of those embodiments, unless the embodiments are inoperable without those elements.

[0153] Additionally, the priority document(s) of this application are incorporated herein by reference in their entireties.

Claims

1. 1. An implantable cardioverter defibrillator device (ICD) including at least two bipolar sensing electrodes, sensing times of arrival of electrical wavefronts at at least two ventricular locations of the heart during cardiac arrhythmias and within heartbeat intervals of the heart; discriminating between atrium-initiated delivery of the wavefront or ventricle-initiated delivery of the wavefront based on a direction of the wavefront passing between the earlier and later sensing electrode locations; discriminate between supraventricular tachycardia or ventricular tachycardia based on the emission of a wavefront initiated from the atrium or the ventricle, and inhibit delivery of a defibrillator shock in response to the cardiac arrhythmia if the supraventricular tachycardia is identified based on a direction of wavefront movement as indicated by the relative timing of the sensing at the at least two locations and calculated with respect to a known direction of a joint axis between the at least two locations in the heart; The at least two bipolar sensing electrodes are configured to be positioned by separate leads at different locations within the right ventricle.

2. The device of claim 1 , wherein the at least two bipolar sensing electrodes are configured to be attached at locations along the ventricular septum.

3. The device of claim 2 , wherein the at least two locations along the ventricular septum are at least 1 cm apart.

4. The device of claim 2 or 3, wherein the two locations along the ventricular septum are disposed along a superior-inferior axis extending along the ventricular septum.

5. The device of claim 1 , wherein the at least two bipolar sensing electrodes are on separate leads.

6. The device of claim 5 , further configured to deliver cardiac contractility modulation (CCM) therapy using the electrodes on the separate lead.

7. The device of claim 6 , wherein the electrodes are used for delivery of CCM therapy and for sensing arrival of an electrical wavefront at the at least two locations.

8. 1. An implantable cardioverter defibrillator device (ICD) including at least two bipolar sensing electrodes, sensing times of arrival of electrical wavefronts at at least two ventricular locations of the heart during cardiac arrhythmias and within heartbeat intervals of the heart; discriminating between atrium-initiated delivery of the wavefront or ventricle-initiated delivery of the wavefront based on a direction of the wavefront passing between the earlier and later sensing electrode locations; discriminate between supraventricular tachycardia or ventricular tachycardia based on the emission of a wavefront initiated from the atrium or the ventricle, and inhibit delivery of a defibrillator shock in response to the cardiac arrhythmia if the supraventricular tachycardia is identified based on a direction of wavefront movement as indicated by the relative timing of the sensing at the at least two locations and calculated with respect to a known direction of a joint axis between the at least two locations in the heart; An implantable cardioverter defibrillator device (ICD), wherein the at least two bipolar sensing electrodes are configured to be positioned on a single lead of the ICD in a right ventricle.

9. The device of claim 8 , wherein the single lead of the ICD is configured for implantation extending along the ventricular septum.

10. 8. The device of claim 1, wherein the at least two bipolar sensing electrodes are configured to be positioned at different locations along a superior-inferior axis within the ventricular septum, and the ICD inhibits delivery of a defibrillation shock when the electrical wavefront is sensed to arrive at a more superior location before arriving at a more inferior location based on an indicated direction of wavefront travel.

11. The device of claim 10 , comprising a sensing electrode configured for placement in a non-septal location in the ventricle.

12. 12. The device of claim 11, wherein the sensing electrode configured for placement at a non-septal location in a ventricle is configured such that delivery of a defibrillation shock is not inhibited if the sensing electrode senses the arrival of an electrical wavefront within a predetermined interval before the ICD senses the electrical wavefront arriving at a ventricular septal location.

13. 13. The device of claim 10, wherein delivery of anti-arrhythmia therapy is not inhibited if the electrical wavefront reaches a lower location before a predetermined delay from reaching a higher location.

14. 1. A method of controlling operation of an implantable cardiac device configured to provide anti-arrhythmic therapy in response to a cardiac arrhythmia, comprising: the implantable cardiac device is connected to at least two bipolar sensing electrodes and to a circuit, the at least two bipolar sensing electrodes being positioned at at least two ventricular locations within the same ventricle; the circuitry sensing a time of arrival of an electrical wavefront at at least two ventricular locations of the heart during a cardiac arrhythmia and within an interval between heartbeats of the heart using the at least two bipolar sensing electrodes; the circuitry discriminating between delivery of the wavefront initiated from the atrium or the ventricle based on a direction of the wavefront passing between an earlier and a later sensing electrode location; the circuit discriminating between supraventricular tachycardia and ventricular tachycardia based on emission of a wavefront initiated from the atrium or the ventricle; and the circuitry providing an input to the implantable cardiac device to inhibit delivery of one or more defibrillation shocks by the implantable cardiac device if the determination is an arrhythmia that is supraventricular tachycardia based on the sensed direction of the electrical wavefront.

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