atrioventricular nodal stimulation

Abstract

Described herein are devices and methods for treating heart conditions using electrical stimulation, using one or more nerve electrodes positioned at a location within the region of the Koch triangle of the right atrium to deliver electrical stimulation to one or both of the AV node and the nerve tissue that innervates the AV node and sense neural activity thereof.

Description

[0001] This application claims the benefit of U.S. Provisional Patent Application No. 62 / 966,352, filed January 27, 2020, which is incorporated herein by reference in its entirety.

[0002] This disclosure relates to apparatus and methods for treating heart disease by delivering electrical stimulation to the atrioventricular node (AV node) or the nerves innervating the AV node.

[0003] Implantable medical devices (IMDs), such as implantable pacemakers, cardioverter-defibrillators, or pacemaker-cardioverter-defibrillators, deliver therapeutic electrical stimulation to the heart. IMDs can provide pacing to resolve bradycardia, or pacing or shock to terminate rapid arrhythmias such as tachycardia or fibrillation. In some cases, the device can sense the heart's inherent depolarization, detect arrhythmias based on (or the absence of) inherent depolarization, and, if an arrhythmia is detected based on inherent depolarization, control the delivery of electrical stimulation to the heart.

[0004] The use of neural stimulation (e.g., vagus nerve stimulation) to treat and manage a variety of medical, psychiatric, and neurological conditions has increased significantly in recent decades, including the treatment of heart disease. The vagus nerve consists of somatic and visceral afferent fibers (which, for example, transmit impulses to the brain) and efferent fibers (which, for example, transmit impulses to effectors to regulate activities such as muscle contraction or glandular secretion).

[0005] Heart rate may be partially limited by parasympathetic stimulation of the left and right vagus nerves. Low vagal activity may be associated with various arrhythmias, including tachycardia, ventricular tachycardia, and rapid atrial fibrillation. Summary of the Invention

[0006] Illustrative apparatus and methods involve atrioventricular node (AV node) stimulation using a device implanted in the right atrium. The device may include one or more neural electrodes configured to stimulate one or both of the AV node or the nerves innervating the AV node. For example, high-voltage stimulation delivered to the AV node can affect conduction through the AV node and influence the inflammatory state by vagal stimulation of the nerves innervating the AV node. Further, for example, low-voltage stimulation delivered to the AV node may affect the cardiac inflammatory state without affecting the ventricular rate or PQ interval. Electrical stimulation can block depolarization conduction via the AV node to the ventricle, but may generally include any stimulation that alters AV node conduction. Electrical stimulation can reduce the conduction velocity through the AV node (“slowing” conduction) to prolong the PR or PQ interval and the VV interval or heart rate. Vagal stimulation can be afferent or efferent. Due to central feedback mechanisms, afferent vagal stimulation can be assumed to affect vagal activity at a more central level. Additionally, inflammatory effects can target the heart, among other organs.

[0007] One or more illustrative devices and methods can be configured to use one or more electrodes to stimulate one or more specific locations to obtain AV node stimulation. These devices and methods may utilize or include two or more circular segmented electrodes to deliver electrical stimulation, for example, to two or more adjacent locations. Illustrative AV node stimulation can be used to delay the ventricular rate during rapidly conducting atrial fibrillation to, for example, prevent inappropriate defibrillation shocks. Further, illustrative AV node stimulation can also be used to reduce inflammatory markers, reduce arrhythmias, and reduce the worsening of heart failure compensatory disorders. Even further, illustrative AV node stimulation can be performed by targeting the parasympathetic nerve innervating the AV node at a distance of approximately 1 cm to approximately 2 cm from the coronary ostium within the Koch triangle. In one example, targeting this specific location within the Koch triangle can be achieved using 50 Hz pacing guided by prolonging the PQ interval during sinus rhythm or prolonging the VV interval during atrial fibrillation.

[0008] An illustrative implantable medical device may include a plurality of electrodes, including at least one neural electrode capable of being implanted in the Koch's triangle region of the right atrium to deliver therapy to or sense neural activity in one or both of the AV node of a patient's heart and the nerve innervating the AV node; a therapy delivery circuit operatively coupled to the plurality of electrodes to deliver therapy to the patient's heart; a sensing circuit operatively coupled to the plurality of electrodes to sense electrical activity in the patient's heart; and a computing device including processing circuitry operatively coupled to the therapy delivery circuitry and the sensing circuitry. The computing device may be configured to deliver electrical stimulation to one or both of the AV node and the nerve innervating the AV node using at least one neural electrode.

[0009] An illustrative method may include providing a plurality of electrodes, the plurality of electrodes including at least one neural electrode, the at least one neural electrode being implantable in the Koch triangle region of the right atrium to deliver therapy or sense neural activity to one or both of the AV node of the patient’s heart or the nerve innervating the AV node; and using at least one neural electrode to deliver electrical stimulation to one or both of the AV node or the nerve innervating the AV node.

[0010] The above overview is not intended to describe every embodiment or every implementation of this disclosure. A more complete understanding will become apparent and understood by taking into account the accompanying drawings and the following detailed description and claims. Attached Figure Description

[0011] Figure 1 This is a conceptual diagram of an illustrative cardiac therapy system that includes an intracardiac medical device implanted in the patient's heart and a separate medical device positioned outside the patient's heart.

[0012] Figure 2 yes Figure 1 An enlarged conceptual diagram of the anatomy of an intracardiac medical device and a patient's heart.

[0013] Figure 3 This is a conceptual diagram of a patient's heart in a standard 17-segment view showing various electrode implantation sites, intended for use with the illustrative systems and devices described herein.

[0014] Figure 4 This is a perspective view of an intracardiac medical device with a distal fixation and electrode assembly for use with the illustrative systems and apparatus described herein, the distal fixation and electrode assembly including a distal housing-based electrode implemented as a ring electrode.

[0015] Figure 5 This is a perspective view of another illustrative intracardiac medical device for use with the illustrative systems and apparatus described herein.

[0016] Figure 6 It is possible to enclose, for example Figure 1-2 Block diagrams of illustrative circuit systems within the housing of medical devices 4-5 to provide the functions and therapies described herein.

[0017] Figure 7 This is a flowchart illustrating a method for treating heart disease using AV node stimulation.

[0018] Figures 8A to 8B This is a timing diagram illustrating an exemplary method for synchronizing a sudden electrical stimulation with various parts of the electrical activity of a patient's heart. Detailed Implementation

[0019] In the following detailed description of illustrative embodiments, reference is made to the accompanying drawings, which form part of the specific embodiments and illustrate, by way of illustration, specific embodiments that can be practiced. It should be understood that other embodiments may be utilized and the scope of the structure may be changed without departing from (e.g., still falling within) the scope of this disclosure herein.

[0020] Reference Figure 1Sections 8 to 8 describe illustrative systems and methods. It will be apparent to those skilled in the art that elements or processes of one embodiment may be used in combination with elements or processes of other embodiments, and that possible embodiments of such apparatus and methods using combinations of features set forth herein are not limited to the specific embodiments shown in the figures and / or described herein. Furthermore, it will be appreciated that the embodiments described herein may include many elements that are not necessarily shown to scale. Still further, it will be appreciated that the timing of the processes and the size and shape of the various elements herein may be modified but still fall within the scope of this disclosure; however, certain timings, one or more shapes and / or sizes, or element types may be preferred over others.

[0021] Abnormal autonomic nervous system activity, such as increased sympathetic tone and decreased parasympathetic tone, can lead to the development of heart failure and trigger sudden cardiac death. Stimulation of the vagus nerve (e.g., efferent or afferent fibers) can reduce the progression of heart failure, prevent recurrent ventricular tachyarrhythmias, reduce infarct size, alleviate myocardial ischemia, help differentiate between atrial and ventricular tachyarrhythmias, and control ventricular rate during supraventricular tachyarrhythmias. Afferent vagal stimulation can affect vagal activity at a more central level due to central feedback mechanisms.

[0022] More specifically, stimulating intracardiac parasympathetic neurons in locations such as near the atrioventricular node (AV node) and the nerves innervating the AV node in the base of the right ventricle can increase parasympathetic tone of the vagus nerve, thereby improving cardiac function, inducing reversal remodeling, reducing myocardial ischemia, decreasing myocardial infarction area, protecting the heart from life-threatening arrhythmias, and providing preemptive treatment for more effective defibrillation shocks or other defibrillation therapies. Electrical stimulation can block depolarization conduction via the AV node to the ventricle, but can generally include any stimulation that alters the vagal activity innervating the AV node, thereby affecting vagal activity and / or conduction at the AV node. For example, vagal stimulation can modulate the cardiac autonomic nervous system by increasing parasympathetic activity to reduce the ventricular rate response to conduction-prone atrial tachyarrhythmias by blocking atrial signals from propagating through the AV node to the ventricle. Furthermore, the mechanisms for cardioprotection via intracardiac parasympathetic stimulation may involve inhibiting sympathetic activation, vagal anti-inflammatory effects, reducing cardiac workload, improving tissue perfusion, antiarrhythmic effects, inducing excessive cardiac innervation, and maintaining a normal ventricular rate during supraventricular tachyarrhythmias. Further, electrical stimulation can be used during episodes of atrial tachyarrhythmias with rapid ventricular conduction to differentiate ventricular tachyarrhythmias from supraventricular tachycardia and prevent the delivery of inappropriate therapy to the patient, such as administering a high-voltage shock due to a misdiagnosis of a ventricular tachyarrhythmia. Delivery of electrical stimulation to the AV node and / or the nerves innervating the AV node can be termed AV node stimulation. In at least one embodiment, in conjunction with conventional cardiac therapies such as cardiac resynchronization therapy, AV node stimulation can be delivered continuously, for example, every 3 or 4 heartbeats.

[0023] The methods described herein can be implemented using one or more different devices (e.g., implantable medical devices). Such devices may include electronic circuits, power supplies, sensors, electrodes, fluid delivery devices, etc. Figure 1 The document describes an illustrative intracardiac medical device that can be used to implement the methods described herein.

[0024] The intracardiac medical device 10 can be used at least to treat cardiac conditions by delivering electrical stimulation to the AV node or the nerve innervating the AV node. While it should be understood that this disclosure can utilize one or both of leadless and ledged implantable medical devices, Figure 1The illustrative cardiac treatment system includes a leadless intracardiac medical device 10 implanted in a patient's heart 8. While, as described herein, the device 10 is configured to deliver electrical stimulation to the AV node or the nerves innervating the AV node, in some embodiments, the device 10 may be configured for single-chamber pacing and may be switchable, for example, between single-chamber and multi-chamber pacing (e.g., dual-chamber or triple-chamber pacing). As used herein, "intracardiac" refers to a device configured to be completely implanted within a patient's heart, for example, to provide cardiac therapy.

[0025] A device 10 is shown implanted in a target implantation region 4 of the right atrium (RA) of a patient's heart 8. The device 10 may include one or more fixation members 20 anchoring the distal end of the device 10 to the atrial endocardium within the target implantation region 4, which is located within the Koch triangle region. The target implantation region 4 may be located between the His bundle 5 and the coronary sinus 3, and may be adjacent to or immediately adjacent to the tricuspid valve 6. Thus, the device 10 can be described as a right atrial implantation device because it is placed in the right atrium.

[0026] Device 10 can be configured to sense neural activity (e.g., parasympathetic activity) of one or both of the AV nodes or the nerves innervating the AV nodes (e.g., different bundles including the AV nodes) using one or more neural electrodes located near the endocardial tissue of the right atrium within the Koch triangle. As further described herein, the neural electrodes can be positioned within the endocardial tissue of the right atrium within the Koch triangle using fixation member 20. In at least one embodiment, the neural electrodes are positioned adjacent to the AV node fat pad in the right atrium.

[0027] The location or orientation of the neural electrodes delivering electrical stimulation to one or both of the AV node or the nerves innervating the AV node can be described more specifically with respect to the coronary ostium. For example, device 10 can be positioned to place or position the neural electrodes to deliver electrical stimulation to an area at 65 to 125 degrees relative to the vertical axis passing through the coronary ostium when viewed from a right anterior oblique angle of 30 degrees. For example, device 10 can be positioned to place or position the neural electrodes to deliver electrical stimulation to an area at 45 to 145 degrees relative to the vertical axis passing through the coronary ostium when viewed from a right anterior oblique angle of 30 degrees.

[0028] For example, device 10 can be positioned to place or position neural electrodes to deliver electrical stimulation to an area 8 to 16 millimeters from the coronary sinus ostium. Further, device 10 can be positioned to place or position neural electrodes to deliver electrical stimulation to an area 2 to 22 millimeters from the coronary sinus ostium. In at least one embodiment, the neural electrodes may be located on a lead extending from device 10 to be positioned to deliver electrical stimulation to one or both of the AV node or the nerve innervating the AV node.

[0029] Furthermore, the device 10 may include a tissue puncture electrode that can be implanted from the Koch's triangle region of the right atrium through the right atrial endocardium and central fibrous body into the base and / or septal region of the left ventricular myocardium of the patient's heart to sense the electrical activity of the left ventricle and / or deliver pacing to the left ventricle.

[0030] Device 10 can be described as a leadless implantable medical device. As used herein, "leadless" means a device without leads extending from the patient's heart 8. Further, although a leadless device may have leads, the leads do not extend from outside the patient's heart to inside the heart or from inside the heart to outside the heart. Some leadless devices can be introduced through a vein, but once implanted, the device has no or may not include any transvenous leads and can be configured to provide cardiac therapy without the use of any transvenous leads. Further, when the device housing is positioned in the atrium, specifically, the leadless device does not use leads to operatively connect to one or more electrodes. Additionally, leadless electrodes can be coupled to the housing of the medical device without the use of leads between the electrode and the housing.

[0031] Device 10 can be configured to monitor one or more physiological parameters of a patient (e.g., the electrical activity of the patient's heart, the chemical activity of the patient's heart, the hemodynamic activity of the patient's heart, and the electroneural activity of the AV node and / or the nerves innervating the AV node). The monitored physiological parameters can then be used by the IMD to detect various cardiac conditions, such as ventricular tachycardia (VT), ventricular fibrillation (VF), supraventricular ventricular tachycardia (SVT), atrial fibrillation (AF), atrial tachycardia (AT), myocardial ischemia / infarction, etc., and to treat these cardiac conditions through therapy. Such therapy may include delivering electrical stimulation to the AV node or the nerves innervating the AV node (e.g., nerve tissue) within the Koch's triangle region of the right atrium, the electrical stimulation being used to pace the patient's heart (e.g., bradycardia pacing, cardiac resynchronization therapy, antitachycardia pacing (ATP), and / or other pacing therapies), etc. Furthermore, in at least one embodiment, the device 10 may be able to deliver high-energy electrical shock pulses for cardioversion / defibrillation therapy delivered in response to, for example, tachycardia detection.

[0032] Device 10 may include multiple electrodes. One or more electrodes may be configured to deliver AV node stimulation and sense neural activity, and such electrodes may be referred to as “neural electrodes.” While neural electrodes may focus primarily on AV node stimulation and sensing, they may also be able to sense electrical activity of the patient’s heart in addition to neural activity, such as depolarization of cardiac tissue, to deliver pacing therapy to the cardiac tissue to induce depolarization, and / or to deliver cardioversion shocks to the cardiac tissue. Illustrative neural electrodes may include a distal shell-based electrode 22 and a non-tissue puncture electrode 322, as further described herein.

[0033] Device 10 may also include a dart electrode assembly 12 defining or having a straight axis extending from a distal region of device 10. The dart electrode assembly 12 may be primarily used to provide ventricular pacing and sensing, and may be positioned or at least configured to pass through the atrial myocardium and central fibrous tissue and enter the ventricular myocardium 14 or along the interventricular septum without completely penetrating the ventricular endocardium or epicardial surface. The dart electrode assembly 12 may carry or include an electrode at the distal region of the axis, such that the electrode can be positioned within the ventricular myocardium for sensing ventricular signals and delivering ventricular pacing pulses (e.g., depolarizing the left and / or right ventricles to induce contraction of the left and / or right ventricles). In some instances, the electrode at the distal region of the axis is a cathode electrode provided for use in a bipolar electrode pair for pacing and sensing. While the implantation region 4 shown allows one or more electrodes of the dart electrode assembly 12 to be positioned in the ventricular myocardium, it should be recognized that devices having the aspects disclosed herein can be implanted in other locations where appropriate for multi-chamber pacing (e.g., dual-chamber or triple-chamber pacing), single-chamber pacing with multi-chamber sensing, single-chamber pacing and / or sensing, or other clinical therapies and applications.

[0034] It should be understood that although the device 10 is described herein as comprising a single dart electrode assembly, the device 10 may include more than one dart electrode assembly placed or configured to pass through the atrial myocardium and central fibrous body and into the ventricular myocardium 14 or along the interventricular septum, without passing entirely through the ventricular endocardium or epicardial surface. Additionally, each dart electrode assembly may carry or include more than a single electrode in a distal region of the axis or in other regions along the axis (e.g., proximal or central regions). In other words, each dart electrode assembly may include one or more electrodes located in a distal region of the axis, which may be used for, for example, bipolar sensing, bipolar pacing, or additional sensing for pacing capture.

[0035] The cardiac therapy system 2 may also include a separate medical device 50 (in Figure 1(Illustrated schematically) A standalone medical device 50 may be positioned outside (e.g., subcutaneously) the patient's heart 8 and may be operatively coupled to the patient's heart 8 to deliver cardiac therapy thereto. In one instance, the standalone medical device 50 may be an extravascular ICD. In some embodiments, the extravascular ICD may include a defibrillation lead that includes or carries a defibrillation electrode. A therapy carrier may be present between the defibrillation electrode on the defibrillation lead and the housing electrode of the ICD. Further, one or more electrodes of the ICD may also be used to sense electrical signals relating to the patient's heart 8. The ICD may be configured to deliver electrical shock therapy including one or more defibrillation or cardioversion shocks. For example, if an arrhythmia is sensed, the ICD may transmit pulses via the lead to shock the heart and restore its normal rhythm. In some instances, the ICD may deliver electrical shock therapy without placing the lead inside the heart or attaching the wire directly to the heart (subcutaneous ICD). Examples of vascular perivascular subcutaneous ICDs that can be used with System 2 described herein can be described in U.S. Patent No. 9,278,229 (Reinke et al.), published March 8, 2016, which is incorporated herein by reference in its entirety.

[0036] In the case of electrical shock therapy (e.g., defibrillation shock delivered by defibrillation electrodes via defibrillation leads), the standalone medical device 50 (e.g., an extravascular ICD) may include control circuitry that uses a therapy delivery circuit to generate a defibrillation shock with any of a variety of waveform characteristics, including leading-edge voltage, slope, delivered energy, pulse phase, etc. The therapy delivery circuitry may, for example, generate monophasic, biphasic, or multiphasic waveforms. Additionally, the therapy delivery circuitry may generate defibrillation waveforms with varying amounts of energy. For example, the therapy delivery circuitry may generate a defibrillation waveform delivering a total of approximately 60-80 joules (J) of energy for subcutaneous defibrillation.

[0037] The individual medical device 50 may further include sensing circuitry. The sensing circuitry may be configured to acquire electrical signals sensed by one or more combinations of electrodes and to process the acquired signals. Components of the sensing circuitry may include analog components, digital components, or combinations thereof. The sensing circuitry may, for example, include one or more sense amplifiers, filters, rectifiers, threshold detectors, analog-to-digital converters (ADCs), etc. The sensing circuitry may convert the sensed signals into digital form and provide the digital signals to control circuitry for processing and / or analysis. For example, the sensing circuitry may amplify the signal from the sensing electrodes and convert the amplified signal into a multi-bit digital signal via an ADC, and then provide the digital signal to the control circuitry. In one or more embodiments, the sensing circuitry may also compare the processed signal with a threshold to detect the presence of atrial or ventricular depolarization (e.g., P wave or R wave) and indicate the presence of atrial depolarization (e.g., P wave) or ventricular depolarization (e.g., R wave) to the control circuitry.

[0038] Device 10 and a separate medical device 50 can cooperate to provide cardiac therapy to a patient's heart 8. For example, device 10 and the separate medical device 50 can be used to detect tachycardia, monitor tachycardia, and / or provide tachycardia-related therapy. For example, device 10 can wirelessly communicate with the separate medical device 50 to trigger an electric shock therapy using the separate medical device 50. As used herein, "wireless" means an operational connection or link between device 10 and the separate medical device 50 that does not use a metallic conductor. In one example, wireless communication can use a unique, signal-conducting, or triggered electrical pulse provided by device 10 that travels through the patient's tissue and can be detected by the separate medical device 50. In another example, wireless communication can use the communication interface (e.g., an antenna) of device 10 to provide electromagnetic radiation that propagates through the patient's tissue and can be detected, for example, using the communication interface (e.g., an antenna) of the separate medical device 50.

[0039] Figure 2 yes Figure 1 An enlarged conceptual diagram of the anatomy of an intracardiac medical device 10 and a patient's heart 8. Specifically, the device 10 is configured to sense electrical activity and / or deliver pacing therapy. The intracardiac device 10 may include a housing 30. The housing 30 may define internal components of the device 10 (such as those used in conjunction with...). Figure 6The generally described sensing circuitry, therapy delivery circuitry, control circuitry, memory, telemetry circuitry, other optional sensors, and power supply reside in a hermetically sealed internal cavity. The housing 30 may include (e.g., formed therefrom or derived therefrom) conductive materials such as titanium or titanium alloys, stainless steel, MP35N (a non-magnetic nickel-cobalt-chromium-molybdenum alloy), platinum alloys, or other biocompatible metals or metal alloys. In other instances, the housing 30 may include (e.g., formed therefrom or derived therefrom) non-conductive materials, including ceramics, glass, sapphire, silicone, polyurethane, epoxy resins, acetyl copolymer plastics, polyetheretherketone (PEEK), liquid crystal polymers, or other biocompatible polymers.

[0040] In at least one embodiment, the housing 30 may be described as extending between the distal region 32 and the proximal region 34 and as defining a generally cylindrical shape, for example, to facilitate catheter delivery. In other embodiments, the housing 30 may be prismatic or any other shape to perform the functions and utilities described herein. The housing 30 may include, for example, a delivery tool interface member 26 defined or positioned at the proximal region 34 for engagement with a delivery tool during implantation of the device 10.

[0041] All or part of the housing 30 may serve as a sensing and / or pacing electrode during cardiac therapy. In the example shown, the housing 30 includes a proximal housing-based electrode 24 external to a proximal portion of the housing 30 (e.g., closer to the proximal region 34 than the distal region 32). When the housing 30 (e.g., defined by or formed of a conductive material such as titanium alloy or other examples listed above) is partially electrically insulated from a non-conductive material (e.g., a coating of parylene, polyurethane, silicone, epoxy resin, or other biocompatible polymers), one or more discrete regions of the conductive material are exposed to form or define a proximal housing-based electrode 24. When the housing 30 (e.g., defined by or formed of a non-conductive material such as ceramic, glass, or polymeric material) is present, a conductive coating or layer, such as titanium, platinum, stainless steel, or alloys thereof, can be applied to one or more discrete regions of the housing 30 to form or define a proximal housing-based electrode 24. In other instances, the proximal housing-based electrode 24 may be a component mounted or assembled onto the housing 30, such as a ring electrode. The proximal housing-based electrode 24 may be electrically coupled to the internal circuitry of the device 10, for example, through a conductive housing 30 or, when the housing 30 is a non-conductive material.

[0042] In the illustrated example, the proximal housing-based electrode 24 is positioned closer to the proximal housing region 34 than the distal housing region 32, and thus can be referred to as the proximal housing-based electrode 24. However, in other examples, the proximal housing-based electrode 24 may be positioned at other locations along the housing 30, for example, further away from the illustrated location.

[0043] At the distal region 32, the device 10 may include a distal fixation and electrode assembly 36, which may include one or more fixation members 20 and one or more dart electrode assemblies 12 of equal or unequal length. In one such example as shown, a single dart electrode assembly 12 includes a shaft 40 extending distally away from the distal region 32 of the housing, and one or more electrode elements, such as a tip electrode 42, at or near the free distal region of the shaft 40. The tip electrode 42 may have a conical or hemispherical distal tip with a relatively narrow tip diameter (e.g., less than about 1 mm) for penetration and through tissue layers without the need for sharp or beveled tips or needle-like tips.

[0044] The dart electrode assembly 12 can be configured to pierce one or more tissue layers to position the tip electrode 42 within a desired tissue layer (e.g., ventricular myocardium). Thus, the height 47 or length of the shaft 40 can correspond to the intended pacing site depth, and the shaft 40 can have relatively high compressive strength along its longitudinal axis to resist bending in the lateral or radial direction when pressed and inserted into the implantation region 4. If a second dart electrode assembly 12 is used, its length may not be equal to the intended pacing site depth and can be configured to act as an independent electrode for delivering pacing energy to and / or sensing signals from said tissue. In one embodiment, a longitudinal axial force can be applied to the tip electrode 42, for example, by applying a longitudinal thrust to the proximal region 34 of the housing 30, to advance the dart electrode assembly 12 into the tissue within the target implantation region. In at least one embodiment, the height 47 or length of the shaft 40 can be adjusted relative to the housing 10 (e.g., it can be adjusted during implantation to deliver stimulation at an appropriate depth).

[0045] Shaft 40 can be described as longitudinally non-compressible and / or elastically deformable in the transverse or radial direction when subjected to transverse or radial forces, allowing for temporary bending, for example, with tissue movement, but returning to its normal straight positioning when the transverse force decreases. Therefore, the dart electrode assembly 12 including shaft 40 can be described as elastic. When shaft 40 is not exposed to any external force or is only exposed to a force along its longitudinal central axis, shaft 40 can maintain a straight, linear positioning as shown.

[0046] In other words, the shaft 40 of the dart electrode assembly 12 can normally be a straight member and can be rigid. In other embodiments, the shaft 40 can be described as relatively rigid, but still possessing limited flexibility in the lateral direction. Further, the shaft 40 can be non-rigid to allow some lateral bending with heart movement. However, in a relaxed state, when not subjected to any external force, the shaft 40 can maintain a straight positioning as shown to space the tip electrode 42 from the distal region 32 of the housing by at least the height or length 47 of the shaft 40.

[0047] The one or more fixation members 20 may be described as one or more “teeth” having a normal bending positioning. The teeth may be held in a distally extending positioning within the delivery tool. The distal tip of the teeth may penetrate cardiac tissue to a limited depth before being resiliently or elastically bent back to the normal bending positioning (as shown) proximally upon release from the delivery tool. Further, the fixation member 20 may include one or more aspects described, for example, in U.S. Patent No. 9,675,579, issued June 13, 2017 (Grubac et al.) and U.S. Patent No. 9,119,959, issued September 1, 2015 (Rys et al.), each of which is incorporated herein by reference in its entirety.

[0048] The distal fixation and electrode assembly 36 includes a distal housing-based electrode 22. The distal housing-based electrode 22 may be a neural electrode configured to deliver electrical stimulation to one or both of the AV node and the nerve innervating the AV node, and to sense neural activity in one or both of the AV node and the nerve innervating the AV node. In one or more embodiments, the distal housing-based electrode 22 may be positioned to contact or be adjacent to the nerve innervating the AV node for stimulation of the AV node. Thus, in this embodiment, although the AV node can be stimulated by the distal housing-based electrode 22, the distal housing-based electrode 22 can directly deliver electrical stimulation to the nerve innervating the AV node, thereby stimulating the AV node.

[0049] When using device 10 as a pacemaker for multi-chamber pacing (e.g., dual-chamber or triple-chamber pacing) and sensing, the tip electrode 42 can serve as a cathode electrode paired with the proximal housing-based electrode 24, which acts as a return anode electrode. Alternatively, the distal housing-based electrode 22 can serve as a return anode electrode paired with the tip electrode 42 for sensing ventricular signals and delivering ventricular pacing pulses. In other instances, the distal housing-based electrode 22 can be a cathode electrode for sensing atrial signals and delivering pacing pulses to the atrial myocardium in the target implantation region 4. When the distal housing-based electrode 22 acts as an atrial cathode electrode, the proximal housing-based electrode 24 can serve as a return anode paired with the tip electrode 42 for ventricular pacing and sensing, and can also serve as a return anode paired with the distal housing-based electrode 22 for atrial pacing and sensing.

[0050] As illustrated in the diagram, in some pacing applications, the target implantation region 4 is along the atrial endocardium 18, typically below the AV node 15 and His bundle 5. The dart electrode assembly 12 may at least partially define the height 47 or length of the shaft 40 to penetrate the atrial endocardium 18 in the target implantation region 4, through the central fibrous body 16, and into the ventricular myocardium 14 without penetrating the ventricular endocardial surface 17. When the height 47 or length of the dart electrode assembly 12 is fully advanced into the target implantation region 4, the tip electrode 42 may be positioned within the ventricular myocardium 14, and the distal housing-based electrode 22 may be positioned in close contact with or very close to the atrial endocardium 18. In various examples, the dart electrode assembly 12 may have a total combined height 47 or length of the tip electrode 42 and shaft 40 of approximately 3 mm to approximately 8 mm. The diameter of the shaft 40 may be less than approximately 2 mm and may be approximately 1 mm or less, or even approximately 0.6 mm or less.

[0051] Device 10 may include acoustic and / or motion detectors 11 within housing 30. The acoustic or motion detectors 11 may be operatively coupled to one or more of control circuitry 80, sensing circuitry 86, or therapy delivery circuitry 84, as per [reference needed]. Figure 6 As described. The acoustic and / or motion detector 11 can be used to monitor mechanical activity, such as atrial mechanical activity (e.g., atrial contraction) and / or ventricular mechanical activity (e.g., ventricular contraction). In some embodiments, the acoustic and / or motion detector 11 can be used to detect right atrial mechanical activity. Non-limiting examples of the acoustic and / or motion detector 11 include one or both of an accelerometer and a microphone. In some embodiments, the mechanical activity detected by the acoustic and / or motion detector 11 can be used to supplement or replace electrical activity detected by one or more electrodes of the device 10. For example, the acoustic and / or motion detector 11 can be used in addition to or as an alternative to the proximal housing-based electrode 24.

[0052] The acoustic and / or motion detector 11 can also be used for rate response detection or to provide a rate-responsive IMD. Various techniques related to rate response can be described in U.S. Patent No. 5,154,170, entitled "Optimization for a rate-responsive cardiac pacemaker," issued October 13, 1992 (Bennett et al.), and U.S. Patent No. 5,562,711, entitled "Method and apparatus for rate-responsive cardiac pacing," issued October 8, 1996 (Yerich et al.), each of which is incorporated herein by reference in its entirety.

[0053] In various embodiments, the acoustic and / or motion detector 11 can be used as a heart sound (HS) sensor and can be implemented as a microphone and / or a one-axis, two-axis, or three-axis accelerometer. In one embodiment, the acoustic and / or motion sensor 11 is implemented as a piezoelectric crystal mounted within a housing 30, the piezoelectric crystal responding to mechanical motion associated with heart sounds. Examples of other embodiments of acoustic sensors that can be adapted to be implemented with the techniques of this disclosure are generally described in U.S. Patent Nos. 4,546,777 (Groch et al.), 6,869,404 (Schulhauser et al.), 5,554,177 (Kieval et al.), and 7,035,684 (Lee et al.), each of which is incorporated herein by reference in its entirety.

[0054] In other words, various types of acoustic and / or motion sensors 11 can be used. For example, the acoustic and / or motion sensor 11 can be described as any implantable or external sensor that responds to one or more heart sounds and thereby is capable of generating or producing analog electrical signals that are time- and amplitude-dependent on the heart sounds. The analog signals can then be processed by the HS sensing module (which may include digital conversion) to obtain HS parameters, such as amplitude or relative time intervals, derived by the HS sensing module or control circuitry 80. The acoustic and / or motion sensor 11 and the HS sensing module can be incorporated into an IMD (e.g., device 10) capable of delivering CRT or another cardiac therapy being optimized, or can be implemented in a separate device with wired or wireless communication to another IMD or in an external programmer or computer used during pacing parameter optimization procedures as described herein.

[0055] Figure 3 Figure 100 is a two-dimensional (2D) ventricular diagram 100 of a patient's heart (e.g., a top-down view), showing the left ventricle 120 and right ventricle 122 in a standard 17-segment view. Figure 100 defines or includes multiple regions 126 corresponding to different areas of the human heart. As illustrated, regions 126 are numbered 1 to 17 (e.g., corresponding to 17 segments of a standard 17-segment human heart model, corresponding to 17 segments of the left ventricle of the human heart). Regions 126 of Figure 100 may include the anterior basal region 1, the anterior basal septum region 2, the subbasal septum region 3, the subbasal region 4, the subbasal lateral region 5, the anterior basal lateral region 6, the mid-anterior region 7, the mid-anterior septum region 8, the mid-inferior septum region 9, the mid-inferior region 10, the mid-inferior lateral region 11, the mid-anterior lateral region 12, the anterior vertex region 13, the vertex septum region 14, the vertex lateral region 15, the vertex lateral region 16, and the apex region 17. The inferior and anterior septal regions of the right ventricle 122, as well as the right bundle branch (RBB) 25 and the left bundle branch (LBB) 27, are also depicted.

[0056] In some embodiments, any tissue-piercing electrode of this disclosure may be implanted in the base and / or septal region of the left ventricular myocardium of a patient's heart. Specifically, the tissue-piercing electrode may be implanted through the right atrial endocardium and central fibrous body from the Koch's triangle region of the right atrium. Once implanted, the tissue-piercing electrode can be positioned in a target implantation area such as the base and / or septal region of the left ventricular myocardium. Figure 1-2 Referring to Figure 100, the basal region includes one or more of the following: anterior basal region 1, anterior basal septal region 2, subbasal septal region 3, subbasal region 4, mid-anterior region 7, mid-anterior septal region 8, mid-inferior septal region 9, and mid-inferior region 10. Referring to Figure 100, the septal region includes one or more of the following: anterior basal septal region 2, anterior basal septal region 3, mid-anterior septal region 8, mid-inferior septal region 9, and apical septal region 14.

[0057] In some embodiments, when implanted, the tissue-puncturing electrode may be positioned in the basal-septal region of the left ventricular myocardium. The basal septal region may include one or more of the following: anterior basal septal region 2, subbasal septal region 3, anterior mid-septal region 8, and inferior mid-septal region 9.

[0058] In some embodiments, when implanted, the tissue-puncturing electrode may be positioned in the superior / posterior basal septal region of the left ventricular myocardium. The superior / posterior basal septal region of the left ventricular myocardium may include a portion of one or more of the subbasal septal region 3 and the mid-inferior septal region 9 (e.g., only the subbasal septal region, only the mid-inferior septal region, or both). For example, the superior / posterior basal septal region may include a region 124 generally illustrated as a dashed boundary. As shown, the dashed boundary indicates the approximate location of the superior / posterior basal septal region, and its shape or size may vary slightly depending on the specific application.

[0059] Figure 4 This is a three-dimensional perspective view of the device 10 capable of delivering pacing therapy and / or delivering sensed cardiac signals. As shown, the distal fixation and electrode assembly 36 includes a distal housing-based electrode 22, which can be used as a neural electrode to sense neural signals and / or deliver electrical stimulation to one or both of the AV node or the nerve innervating the AV node, implemented as a ring electrode. As described herein, the distal housing-based electrode 22 can be configured to be located or positioned in contact with the nerve innervating the AV node and can deliver electrical stimulation to the nerve innervating the AV node, thereby delivering electrical stimulation to the AV node. The distal housing-based electrode 22 can be positioned to closely contact or operatively approach the atrial tissue near the AV node when the fixation member teeth 20a, 20b, and 20c of the fixation member 20 engage with atrial tissue. The elastically deformable teeth 20a, 20b, and 20c can extend distally during delivery of the device 10 to the implantation site. For example, when device 10 is ejected from the delivery tool, the teeth 20a, 20b, and 20c can pierce the atrial endocardial surface and bend back to their normal bending position when the teeth are no longer constrained within the delivery tool (as shown). As the teeth 20a, 20b, and 20c bend back to their normal position, the fixation member 20 can pull the distal fixation member and electrode assembly 36 toward the atrial endocardial surface. When the distal fixation member and electrode assembly 36 are “pulled” toward the atrial endocardium, the tip electrode 42 can be advanced through the atrial myocardium and central fibrous body and into the ventricular myocardium. The distal shell-based electrode 22 can then be positioned close to or adjacent to the atrial endocardial surface near the AV node. In at least one embodiment, at least one neural electrode, such as the tip electrode 42 or the shell-based electrode 22, can be positioned to deliver electrical stimulation to an area (e.g., the AV node region) at 65 to 125 degrees relative to the vertical axis passing through the coronary sinus ostium when viewed from a right anterior oblique 30-degree angle.

[0060] The distal shell-based electrode 22 can be a neural electrode, which may include (e.g., formed therefrom) a conductive material (such as titanium, platinum, iridium, or alloys thereof). In one embodiment, the distal shell-based electrode 22 may be a single continuous ring electrode. In another embodiment, the distal shell-based electrode 22 may include two or more electrode portions defining a segmented ring. Each of these two or more electrode portions of the segmented ring can be used separately from each other or in conjunction with other electrode portions. Thus, once the device 10 is implanted into the target region 4, two or more electrode portions can be used independently to sense neural signals or to deliver electrical stimulation to slightly different locations.

[0061] In other examples, portions of the distal housing-based electrode 22 may be coated with an electrically insulating coating, such as parylene, polyurethane, silicone, epoxy, or other insulating coatings, to reduce the conductive surface area of ​​the electrode. For example, one or more sectors of the distal housing-based electrode 22 may be coated to separate two or more conductive exposed surface areas of the distal housing-based electrode 22. Reducing the conductive surface area of ​​the distal housing-based electrode 22 by covering portions of the conductive area with an insulating coating can increase the impedance of the distal housing-based electrode 22 and thereby reduce the current delivered during pacing pulses to capture myocardium (e.g., atrial myocardial tissue). Lower current consumption can save power to the device 10, such as one or more rechargeable or non-rechargeable batteries.

[0062] As described above, the distal shell-based electrode 22 can be configured as a neural electrode for delivering AV node stimulation and sensing neural signals. However, alternatively, the distal shell-based electrode 22 can be configured as an atrial cathode electrode for delivering pacing pulses to the atrial tissue at the implantation site 4 in conjunction with the proximal shell-based electrode 24, which serves as the return anode. Electrodes 22 and 24 can also be used to sense cardiac depolarization activities, such as atrial activity (e.g., P wave), ventricular activity (e.g., QRS complex and T wave), etc., for controlling neural stimulation using electrode 22, for example, delivering neural stimulation during the refractory period following the P wave, QRS complex, etc. Additionally, electrodes 22 and 24 can be used to sense cardiac depolarization activities, such as the P wave used in atrial pacing pulses (delivered even when no P wave is sensed), and to control atrial-synchronized ventricular pacing pulses delivered using the tip electrode 42 as the cathode and the proximal shell-based electrode 24 as the return anode. In other instances, the distal housing-based electrode 22 may be combined with the cathode tip electrode 42 for ventricular pacing and sensing as a return anode. It should be understood that the distal housing-based electrode 22 performs more than the therapeutic and sensing functions described herein. For example, the distal housing-based electrode 22 may deliver AV junction stimulation, deliver conventional atrial pacing, and sense atrial activity (e.g., during different parts of the cardiac cycle, during multiple heartbeats, etc.).

[0063] Figure 5This is a three-dimensional perspective view of another leadless intracardiac medical device 310, which can be configured to treat heart conditions by AV junction stimulation and / or delivery of pacing therapy for single-chamber or multi-chamber cardiac therapies (e.g., dual-chamber or triple-chamber cardiac therapies). Device 310 may include a housing 330 having an outer wall 335, shown as a cylindrical outer wall, extending from a distal region 332 of the housing to a proximal region 334. The housing 330 may enclose an electronic circuitry system configured to perform single-chamber or multi-chamber cardiac therapies, including atrial and ventricular cardiac electrical signal sensing and pacing of the atrial and ventricular chambers. A delivery tool interface component 326 is shown on the proximal region 334 of the housing.

[0064] The distal fixation and electrode assembly 336 can be coupled to the distal region 332 of the housing. The distal fixation and electrode assembly 336 may include an electrically insulating distal member 372 coupled to the distal region 332 of the housing. A tissue-piercing electrode assembly 312 may extend remotely from the distal region 332 of the housing, and a plurality of non-tissue-piercing electrodes 722 may be directly coupled to the insulating distal member 372. As shown, the tissue-piercing electrode assembly 312 extends in a longitudinal direction remote from the distal region 332 of the housing and may be coaxial with the longitudinal central axis 331 of the housing 330.

[0065] The distal tissue puncture electrode assembly 312 may include an electrically insulating shaft 340 and a tip electrode 342 (e.g., a tissue puncture electrode). As described herein, embodiments may include multiple electrodes positioned along the insulating shaft 340. In some instances, the tissue puncture electrode assembly 312 may be described as a movable, fixed member including a helical shaft 340 and a distal cathode tip electrode 342. The helical shaft 340 may extend from a distal region 343 to a proximal region 341, which may be directly coupled to the insulating distal member 372. The helical shaft 340 may be coated with an electrically insulating material, such as parylene or other examples listed herein, to avoid sensing or stimulating cardiac tissue along the shaft length.

[0066] As described herein, the tip electrode 342 is located or positioned at the distal axial region 343 and can serve as a cathode electrode for delivering ventricular pacing pulses and sensing ventricular electrical signals using the proximal housing-based electrode 324 as a return anode when the tip electrode 342 is advanced toward or into ventricular tissue. The proximal housing-based electrode 324 can be an annular electrode of the outer housing 330 and can be defined by an uninsulated portion of the longitudinal sidewall 335. Other portions of the housing 330 that do not function as electrodes can be used in conjunction with the above description. Figure 4 The device 10 is coated with a similar electrically insulating material.

[0067] Using two or more tissue-puncture electrodes that penetrate into the LV myocardium (e.g., any type of tissue-puncture electrode) can be used for more localized pacing capture and can reduce ventricular pacing spikes, thereby affecting the capture of atrial tissue. In some embodiments, multiple tissue-puncture electrodes may comprise two or more dart-shaped electrode assemblies (e.g., Figure 4 Electrode assemblies 12), helical electrodes. Non-limiting examples of multiple tissue-piercing electrodes include two dart-shaped electrode assemblies, a helical electrode having a dart electrode assembly extending therethrough (e.g., through the center), or a double-wound helix. Multiple tissue-piercing electrodes can also be used for bipolar or multipolar pacing.

[0068] In some embodiments, one or more tissue puncture electrodes (e.g., any type of tissue puncture electrode) penetrating into the LV myocardium can be multipolar tissue puncture electrodes. Multipolar tissue puncture electrodes may include one or more electroactive elements and electrodissociation elements, enabling bipolar or multipolar pacing from one or more tissue puncture electrodes. In other words, each tissue puncture electrode may include one or more separate electrodes or electroactive segments or regions independent of each other.

[0069] Multiple non-tissue puncture electrodes 322 may be provided along the outer periphery of the insulating distal member 372, located on the outer periphery of the tissue puncture electrode assembly 312. The non-tissue puncture electrodes 322 may serve as neural electrodes to sense neural activity and / or deliver electrical stimulation to one or both of the AV node or the nerve innervating the AV node. The insulating distal member 372 may define a distally facing surface 338 of the device 310 and a circumferential surface 339 of the device 310 adjacent to the longitudinal sidewall 335 of the housing. The non-tissue puncture electrodes 322 may be formed of a conductive material such as titanium, platinum, iridium, or alloys thereof. In the illustrated embodiment, six non-tissue puncture electrodes 322 are radially spaced at equal distances along the outer periphery of the insulating distal member 372; however, two or more non-tissue puncture electrodes 322 may be provided.

[0070] The non-tissue puncture electrode 322 may be a discrete component, each held within a corresponding recess 374 in the insulating member 372, the size and shape of which are designed to match the non-tissue puncture electrode 322. In other examples, the non-tissue puncture electrode 322 may each be an uninsulated exposed portion of a monolithic member mounted within or above the insulating distal member 372. Intermediate portions of the monolithic member that do not function as electrodes may be insulated by the insulating distal member 372, or, if exposed to the surrounding environment, may be coated with an electrically insulating coating, such as parylene, polyurethane, silicone, epoxy, or other insulating coatings.

[0071] When the tissue-piercing electrode assembly 312 is advanced into the cardiac tissue, at least one non-tissue-piercing electrode 322 may be positioned against, in close contact with, or operatively close to the surface of the cardiac tissue for delivering AV node stimulation and / or sensing neural activity from or innervating the AV node. For example, the non-tissue-piercing electrode 322 may be positioned in contact with the right atrial endocardial tissue for AV node stimulation and neural activity sensing as the tissue-piercing electrode assembly 312 is advanced into the atrial tissue and through the central fibrous body, until the distal tip electrode 342 is positioned in direct contact with ventricular tissue, such as ventricular myocardium and / or a portion of the ventricular conduction system.

[0072] The non-tissue puncture electrode 322 can be coupled to the therapy delivery circuitry and sensing circuitry, as will be referenced herein. Figure 6 Described, the therapy delivery circuitry and sensing circuitry are encapsulated in a housing 330. When delivering AV junction stimulation, the non-tissue puncture electrode 322 can operate in combination as a cathode electrode with a proximal housing-based electrode 324 acting as a return anode to deliver neural electrical impulses and to sense neural activity, such as parasympathetic activity. When delivering conventional pacing therapy, the non-tissue puncture electrode 322 can operate in combination as a cathode electrode with a proximal housing-based electrode 324 acting as a return anode to deliver atrial pacing impulses and to sense atrial electrical signals, such as P waves. A switching circuitry system included in the sensing circuitry can be activated under the control of a control circuitry to connect one or more non-tissue puncture electrodes to an atrial sensing channel. The distal non-tissue puncture electrodes 322 can be electrically isolated from each other, allowing each individual electrode in the electrodes 322 to be individually selected, either alone or in combination of two or more electrodes in the electrodes 322, to act as an atrial cathode electrode via the switching circuitry system included in the therapy delivery circuitry. The switching circuit system included in the therapy delivery circuit can be activated under the control of the control circuit to couple one or more of the non-tissue puncture electrodes 322 to the atrial pacing circuit. Two or more of the non-tissue puncture electrodes can be selected at once to be used as multiple atrial cathode electrodes.

[0073] Certain (e.g., one or more) non-tissue puncture electrodes 322 selected for AV node stimulation, nerve sensing, atrial pacing, and / or atrial sensing can be chosen based on AV node capture testing, atrial capture testing, electrode impedance, and / or other factors. For example, a single non-tissue puncture electrode 322 or any combination of two or more of the aforementioned non-tissue puncture electrodes can be selected as the optimal combination of a cathode electrode providing a low pacing capture threshold amplitude and relatively high electrode impedance to achieve reliable atrial pacing using minimal current consumption from the power source.

[0074] In some cases, when the tissue-piercing electrode assembly 312 anchors the housing 330 at the implantation site 4, the distally facing surface 338 can uniformly contact the atrial endocardial surface. In this case, all electrodes 322 can be selected together to form an atrial cathode. Alternatively, every other electrode of the electrodes 322 can be selected together to form a multi-center atrial cathode with higher impedance, the atrial cathodes still being uniformly distributed along the distally facing surface 338. Alternatively, a subset of one or more electrodes 322 can be selected along one side of the insulating distal member 372 to provide pacing at a desired site that achieves the lowest pacing capture threshold due to the relative position of the electrodes 322 to the paced atrial tissue.

[0075] In other cases, depending on the positioning and orientation of the tissue-piercing electrode assembly 312 into the cardiac tissue, the distally facing surface 338 may be oriented at an angle relative to the adjacent endocardial surface. In this case, one or more of the non-tissue-piercing electrodes 322 may be positioned to make closer contact with the adjacent endocardial tissue than other non-tissue-piercing electrodes 322, which may be oriented at an angle away from the endocardial surface. By providing a plurality of non-tissue-piercing electrodes along the periphery of the insulating distal member 372, the angles of the tissue-piercing electrode assembly 312 and the distal housing region 332 relative to the cardiac surface (e.g., the right atrial endocardial surface) need not be substantially parallel. Anatomical and positioning differences may cause the distally facing surface 338 to be angled or tilted relative to the endocardial surface; however, the plurality of non-tissue-piercing electrodes 322 distributed along the periphery of the insulating distal member 372 increases the likelihood of good contact between one or more electrodes 322 and the adjacent cardiac tissue, thereby facilitating acceptable pacing thresholds and reliable cardiac event sensing using at least a subset of the plurality of electrodes 322. It may not be necessary to make circumferential contact or fixation along the entire outer periphery of the insulating distal member 372.

[0076] The non-tissue puncture electrodes 322 are shown each comprising a first portion 322a extending along a distally facing surface 338 and a second portion 322b extending along a circumferential surface 339. The first portion 322a and the second portion 322b may be continuous exposed surfaces such that the active electrode surface wraps around an outer peripheral edge 376 of the insulating distal member 372, the outer peripheral edge joining the distally facing surface 338 and the circumferential surface 339. The non-tissue puncture electrodes 322 may include one or more electrodes 322 along the distally facing surface 338, one or more electrodes along the circumferential surface 339, one or more electrodes each extending along both the distally facing surface 338 and the circumferential surface 339, or any combination thereof. The exposed surface of each non-tissue puncture electrode in the non-tissue puncture electrodes 322 may be flush with the corresponding distally facing surface 338 and / or circumferential surface. In other embodiments, each non-tissue puncture electrode in the non-tissue puncture electrodes 322 may have a raised surface protruding from the insulating distal member 372. However, any raised surface of electrode 322 can define a smooth or round non-tissue puncture surface.

[0077] The distal fixation and electrode assembly 336 can seal the distal region of the housing 330 and can provide a base for mounting the electrode 322 thereon. The electrode 322 may be referred to as a housing-based electrode. The electrode 322 may not be carried by an active electrode portion (such as a distal tip electrode 342 located at the distal tip of a helical shaft 340 extending away from the housing 330) extending away from the housing 330 via a shaft or other extension. Other examples of non-tissue-piercing electrodes coupled to the distally facing surface and / or circumferential surface of an insulating distal member, as presented herein, include those described herein. Figure 4 The distal housing-based electrode 22 described in the device 10, as per this document... Figure 4 The device 10 describes a distal housing-based electrode, button electrode, other housing-based electrode, and other circumferential annular electrode extending circumferentially around the assembly 36. Any non-tissue puncture electrode located peripheral to the central tissue puncture electrode and directly coupled to the distal insulating member can be provided as a cathode electrode, individually, jointly, or in any combination, for delivering pacing pulses to adjacent cardiac tissue. When annular electrodes, such as the distal housing-based electrode 22 and / or circumferential annular electrodes, are provided, portions of the annular electrode may be electrically insulated by a coating to provide a plurality of distributed non-tissue puncture electrodes along the distally facing surface and / or circumferential surface of the insulating distal member.

[0078] Compared to the tissue-piercing electrode provided by the distal fixation and electrode assembly 336, the non-tissue-piercing electrode 322 and other examples listed above are expected to provide more reliable and effective AV node stimulation, neural activity sensing, atrial pacing, and atrial depolarization sensing. The atrial cavity wall is relatively thin compared to the ventricular cavity wall. A tissue-piercing atrial cathode electrode may extend too deeply within the atrial tissue, resulting in unintentional continuous or intermittent capture of the ventricular tissue. Because the ventricular signal has a greater signal intensity in the cardiac electrical signals received by the tissue-piercing atrial cathode electrode, which is physically closer to the ventricular tissue, the tissue-piercing atrial cathode electrode may interfere with the sensing of atrial signals. The tissue-piercing electrode assembly 312 can be securely anchored in the ventricular tissue to stabilize the implantation location of the device 310 and reasonably ensure that the tip electrode 342 performs sensing and pacing in the ventricular tissue, while the non-tissue-piercing electrode 322 reliably provides electrical stimulation and sensing of one or both of the AV node or the nerve innervating the AV node and / or pacing and sensing of the atrial tissue. As described herein, the non-tissue puncture electrode 322 can be positioned to contact or be adjacent to the nerve innervating the AV node and deliver electrical stimulation thereto, thereby delivering electrical stimulation to the AV node, or sense electrical activity from the nerve innervating the AV node, thereby sensing electrical activity of the AV node. When the device 310 is implanted in the target implantation area 4, for example, as Figures 1 to 2 As shown in the device 10, the tip electrode 342 can reach the left ventricular tissue for pacing of the left ventricle, while the non-tissue-piercing electrode 322 electrically stimulates and senses one or both of the AV node or the nerve innervating the AV node and / or paces and senses the atrial tissue. The length of the tissue-piercing electrode assembly 312 from the distally facing surface 338 can be in the range of about 4 mm to about 8 mm to reach the left ventricular tissue. In some cases, the device 310 can achieve bi-atrial (right and left atrium) capture by delivering atrial pacing pulses from the therapy delivery circuit 84 via the non-tissue-piercing electrode 322 in the target implantation area 4, and bi-ventricular (right and left ventricle) capture by delivering ventricular pacing pulses from the ventricular pacing circuit via the tip electrode 342 advanced from the target implantation area 4 into the ventricular tissue, thereby achieving four-chamber pacing.

[0079] Figure 6 This is a block diagram of a circuit that, according to one example, can be encapsulated within the housings 30 and 330 of devices 10 and 310 to provide functions such as sensing neural activity (e.g., parasympathetic activity, sympathetic activity, etc.), delivering neural electrical stimulation, sensing cardiac signals, determining capture and / or delivering pacing therapy, or can be encapsulated within the housing of any other medical device described herein. A standalone medical device 50 (such as...) Figure 1The devices (shown) may include some or all of the same components that can be configured in a similar manner. The electronic circuitry encapsulated within housings 30, 330 may include software, firmware, and hardware that collaboratively detect and decode neural signals, detect atrial and ventricular electrical cardiac signals, determine whether cardiac capture has occurred, determine when cardiac therapy is needed, and deliver electrical nerve stimulation to one or both of the AV nodes or the nerves innervating the AV nodes and / or deliver electrical pulses to the patient's heart according to programmed treatment modes and pulse control parameters. The electronic circuitry system may include control circuitry 80 (e.g., including processing circuitry), memory 82, therapy delivery circuitry 84, sensing circuitry 86, and / or telemetry circuitry 88. In some instances, devices 10, 310 include one or more sensors 90 for generating signals related to one or more physiological functions, states, or symptoms of the patient. For example, one or more sensors 90 may include patient activity sensors for determining the need for pacing therapy and / or controlling the pacing rate. Further, for example, one or more sensors 90 may include an inertial measurement unit (e.g., an accelerometer) for measuring motion. Further, for example, one or more sensors 90 may include acoustic sensors to monitor heart sounds. Still further, for example, one or more sensors 90 may include patient activity sensors, which may include accelerometers. An increase in the patient's metabolic demand due to an increase in activity as indicated by the patient activity sensor can be determined using the patient activity sensor. In other words, devices 10, 310 may include additional sensors 90 for sensing signals from the patient to determine whether to deliver and / or control electrical stimulation therapy delivered by the therapy delivery circuit 84.

[0080] Power supply 98 can provide power as needed to the circuitry of devices 10, 310, including each of components 80, 82, 84, 86, 88, 90. Power supply 98 may include one or more energy storage devices, such as one or more rechargeable or non-rechargeable batteries. The connections between power supply 98 and each of components 80, 82, 84, 86, 88, 90 (not shown) can be understood from a general block diagram shown to a person skilled in the art. For example, power supply 98 may be coupled to one or more charging circuits included in therapy delivery circuitry 84 to provide power for charging a holding capacitor included in therapy delivery circuitry 84, which discharges at appropriate times under the control of control circuitry 80 for delivering neural stimulation and / or pacing pulses. Power supply 98 may also be coupled to components of sensing circuitry 86 (such as sensing amplifiers, analog-to-digital converters, switching circuitry, etc.), sensor 90, telemetry circuitry 88, and memory 82 to provide power to various circuits.

[0081] The illustrated functional blocks represent the functions included in devices 10, 310, and may include any discrete and / or integrated electronic circuit components implementing analog and / or digital circuitry capable of producing the functions attributed to the medical devices 10, 310 described herein. Individual components may include processing circuitry systems (such as application-specific integrated circuits (ASICs), electronic circuitry, processors (shared, dedicated, or grouped), and memories) executing one or more software or firmware programs, combinational logic circuits, state machines, or other suitable components or combinations of components providing the described functions. The specific form of software, hardware, and / or firmware used to implement the functions disclosed herein will be determined primarily by the specific system architecture employed in the medical device and the specific detection and therapy delivery methods used by the medical device.

[0082] Memory 82 may include any volatile, non-volatile, magnetic, or electrically non-transitory computer-readable storage medium, such as random access memory (RAM), read-only memory (ROM), non-volatile RAM (NVRAM), electrically erasable programmable ROM (EEPROM), flash memory, or any other memory device. Furthermore, memory 82 may include a non-transitory computer-readable medium storing instructions that, when executed by one or more processing circuits, cause control circuit 80 and / or other processing circuits to sense and decode neural activity, perform neural electrical stimulation, determine cardiac conduction system capture and / or perform single-chamber, dual-chamber, or triple-chamber calibrated pacing therapy (e.g., single-chamber or multi-chamber pacing), or other cardiac therapeutic functions attributed to devices 10, 310 (e.g., sensing or delivering therapy). The non-transitory computer-readable medium storing instructions may include any of the media listed above.

[0083] The control circuit 80 may communicate with the therapy delivery circuit 84 and the sensing circuit 86, for example via a data bus, to sense cardiac electrical signals and control the delivery of cardiac electrical stimulation therapy in response to neural activity (e.g., reduced parasympathetic activity), sensed cardiac events (e.g., P waves and R waves), or their absence. The tip electrodes 42, 342, the distal housing-based electrodes 22, 322, and the proximal housing-based electrodes 24, 324 may be electrically coupled to the therapy delivery circuit 84 for delivering electrical stimulation pulses to the sensing circuit 86 and for sensing electrical signals.

[0084] Distal shell-based electrodes 22, 322 and proximal shell-based electrodes 24, 324 may be coupled to sensing circuitry 86 for sensing neural activity from or innervating one or both of the AV node and the nerves innervating the AV node, and for sensing atrial signals, such as P waves associated with atrial myocardial depolarization. In instances including two or more selectable distal shell-based electrodes, sensing circuitry 86 may include switching circuitry for selectively coupling one or more available distal shell-based electrodes to event detection circuitry. The switching circuitry system may include a switch array, switch matrix, multiplexer, or any other type of switching device suitable for selectively connecting components of sensing circuitry 86 to selected electrodes. Tip electrodes 42, 324 and proximal shell-based electrodes 24, 324 may be coupled to sensing circuitry 86 for sensing ventricular signals, such as R waves associated with ventricular myocardial depolarization.

[0085] As described herein, sensing circuit 86 may include event detection circuitry for detecting neural activity (e.g., parasympathetic activity, sympathetic activity, efferent neural activity, and / or afferent neural activity) and cardiac depolarization activity (e.g., P wave, QRS complex, R wave, etc.). The event detection circuitry may be configured to amplify, filter, digitize, and rectify electrical signals received from selected electrodes to improve signal quality for detecting neural and cardiac electrical events. Event detection circuitry may include one or more sense amplifiers, filters, rectifiers, threshold detectors, comparators, analog-to-digital converters (ADCs), timers, or other analog or digital components. Event sensing thresholds (e.g., neural activity sensing thresholds, P wave sensing thresholds, and R wave sensing thresholds, etc.) may be automatically adjusted under the control of control circuitry 80, for example, based on a time period and sensing threshold determined by control circuitry 80, stored in memory 82, and / or controlled by the hardware, firmware, and / or software of control circuitry 80 and sensing circuitry 86.

[0086] Upon detecting a neural or cardiac electrical event based on a sensing threshold crossover, sensing circuit 86 can generate a sensing event signal that is transmitted to control circuit 80. For example, sensing circuit 86 can generate a parasympathetic activity reduction signal in response to a parasympathetic activity sensing threshold crossover. Further, for example, sensing circuit 86 can generate an efferent neural activity reduction signal in response to an efferent neural activity sensing threshold crossover. Further, for example, sensing circuit 86 can generate a P-wave sensing event signal in response to a P-wave sensing threshold crossover and an R-wave sensing event signal in response to an R-wave sensing threshold crossover. Control circuit 80 can use the sensed event signals to set a pacing escape interval timer that controls the basic time interval used to schedule cardiac pacing pulses. The sensed event signals can trigger or inhibit neural stimulation and / or pacing pulses according to a specifically programmed pacing pattern. For example, a P-wave sensing event signal received from sensing circuit 86 can cause control circuit 80 to initiate an atrial blanking interval during which, for example, AV node stimulation can be delivered. Furthermore, for example, an R-wave sensing event signal received from sensing circuit 86 can cause control circuit 80 to initiate a ventricular blanking interval during which, for example, AV node stimulation can be delivered.

[0087] Additionally, regarding pacing therapy, for example, a P-wave sensing event signal received from sensing circuit 86 can cause control circuit 80 to suppress a predetermined atrial pacing pulse and schedule a ventricular pacing pulse with a programmed atrioventricular (AV) pacing interval. If an R-wave is sensed before the AV pacing interval expires, the ventricular pacing pulse can be suppressed. If the AV pacing interval expires before control circuit 80 receives an R-wave sensing event signal from sensing circuit 86, control circuit 80 can use therapy delivery circuit 84 to deliver a predetermined ventricular pacing pulse synchronized with the sensed P-wave.

[0088] In some instances, devices 10, 310 can be configured to deliver various therapies, including AV node stimulation, bradycardia pacing, cardiac resynchronization therapy, post-shock pacing, and / or tachycardia-related therapies such as ATP. For example, devices 10, 310 can be configured to detect supraventricular tachycardia and deliver AV node stimulation. Further, for example, devices 10, 310 can be configured to deliver AV node stimulation in response to monitored parasympathetic activity (e.g., reduced parasympathetic activity) and / or monitored efferent activity (e.g., reduced efferent activity). Even further, for example, devices 10, 310 can be configured to deliver AV node stimulation in response to the detection of a cardiac inflammatory state, to provide an anti-inflammatory effect to the patient's heart, for example, without affecting the ventricular rate or PQ interval. Detection of a cardiac inflammatory state can be performed by monitoring the patient's cardiac electrical activity and, for example, assessing heart rate variability. Furthermore, for example, devices 10, 310 can be configured to deliver vagal nerve stimulation to the nerves innervating the AV node in response to the detection of voluntary imbalance.

[0089] Additionally, for example, devices 10, 310 can be configured to detect non-sinus tachycardia and deliver anti-tachycardia pacing (ATP). Control circuitry 80 can determine cardiac event time intervals, such as the PP interval between consecutive P-wave sensed event signals received from sensing circuitry 86, the RR interval between consecutive R-wave sensed event signals received from sensing circuitry 86, and the PR and / or RP intervals received between P-wave and R-wave sensed event signals. These intervals can be compared to tachycardia detection intervals to detect non-sinus tachycardia. Tachycardia can be detected in a given cardiac chamber based on a threshold number of detected tachycardia detection intervals.

[0090] The therapy delivery circuit 84 may include a charging circuit, one or more charge storage devices such as one or more low-voltage holding capacitors, an output capacitor, and / or a switching circuit that controls the charging and discharging time of the holding capacitor on the output capacitor to deliver electrical stimulation (e.g., AV junction stimulation, cardiac pacing, etc.) to one or more selected electrodes. Tip electrodes 42, 342, proximal housing-based electrodes 24, 324, and distal housing-based electrodes 22, 322 may be selectively coupled to the therapy delivery circuit 84 for delivering AV junction stimulation, atrial pacing pulses, ventricular pacing pulses, etc. The therapy delivery circuit 84 may be configured to deliver ventricular pacing pulses, for example, upon the expiration of the AV or VV pacing interval set by the control circuit 80, to provide atrial synchronized ventricular pacing and a substantially low ventricular pacing rate. The therapy delivery circuit 84 may be configured to deliver atrial pacing pulses if the atrial pacing interval expires before a P-wave sensing event signal is received from the sensing circuit 86. The control circuit 80 initiates an AV pacing interval in response to the delivered atrial pacing pulse to provide synchronized multi-chamber pacing (e.g., dual-chamber or triple-chamber pacing).

[0091] The holding capacitor of the therapy circuit 84 can be charged to a programmed pacing voltage amplitude and discharged to a programmed pacing pulse width based on control signals received from the control circuit 80. For example, the timing circuit included in the control circuit 80 may include a programmable digital counter set by the microprocessor of the control circuit 80 for controlling the basic time intervals associated with various AV junction stimulation, single-chamber or multi-chamber pacing (e.g., dual-chamber or triple-chamber pacing) modes, and anti-tachycardia pacing sequences. The microprocessor of the control circuit 80 may also set the amplitude, pulse width, polarity, or other characteristics of the AV junction stimulation and cardiac pacing pulses based on programmed values ​​stored in memory 82.

[0092] Control parameters for sensing cardiac events and controlling the delivery of pacing therapy, utilized by control circuitry 80, can be programmed into memory 82 via telemetry circuitry 88, which can also be described as a communication interface. Telemetry circuitry 88 includes a transceiver and antenna for communicating with external devices such as programmers or home monitors using radio frequency communication or other communication protocols. Control circuitry 80 can use telemetry circuitry 88 to receive downlink telemetry from external devices and transmit uplink telemetry to external devices. In some cases, telemetry circuitry 88 can be used to transmit and receive communication signals to and from another medical device implanted in the patient.

[0093] The illustrative systems, methods, and apparatus described herein can be used or configured to treat cardiac conditions in patients using AV node stimulation. Figure 7The document describes an illustrative method 200 for treating a patient's cardiac condition using AV node stimulation. Generally, the illustrative method 200 may be described as collecting data from the patient, analyzing such data to determine if there is a cardiac condition that can be treated with AV node stimulation or another cardiac therapy, delivering AV node stimulation, and then terminating AV node stimulation for various reasons.

[0094] As shown in the figure, method 200 includes data collection 202. Generally, data collection 202 may include monitoring the patient's physiological parameters (e.g., at least one physiological parameter), such as the patient's cardiac electrical activity, the patient's cardiac chemical activity, the patient's cardiac hemodynamic pressure, the patient's neural electrical activity, and the physical motion of parts of the patient's heart (e.g., using an accelerometer), etc.

[0095] The neural activity of the patient's heart may include one or more signals monitored from locations within or around the patient's nerves (e.g., using electrodes, such as those on devices 10, 50, 310). More specifically, electrical signals propagate along or through one or more nerve fibers of the patient's AV nodes, regions adjacent to the patient's AV nodes, and / or nerves innervating the AV nodes of the patient's heart. Such signals may include parasympathetic and sympathetic signals propagating along efferent and afferent nerve fibers.

[0096] The electrical activity of a patient's heart can include one or more signals that can be monitored from locations within or around the patient's heart (e.g., using electrodes, such as those on devices 10, 50, 310). Using the detected electrical activity of the patient's heart, certain metrics can be determined and collected (e.g., for analysis). For example, the electrical activity of the patient's heart can be used to determine and collect the following metrics: heart rate (HR), heart rate variability (HRV), heart rate disturbance (HRT), deceleration / acceleration capacity, deceleration sequence occurrence rate, T-wave alternation (TWA), electrocardiogram, P-wave to P-wave interval (also known as PP interval or AA interval), R-wave to R-wave interval (also known as RR interval or VV interval), P-wave to QRS complex interval (also known as PR interval, AV interval, or PQ interval), QRS complex morphology, ST segment (i.e., the segment connecting the QRS complex and the T wave), T-wave variation, QT interval, electrical vector, etc.

[0097] The chemical activity of a patient's heart can include one or more chemical properties that can be monitored from locations within or around the patient's heart (e.g., using various sensors). Using this monitored chemical activity, certain metrics can be identified and collected (e.g., for analysis). For example, the chemical activity of a patient's heart can be used to identify and collect metrics such as: blood oxygen saturation, brain natriuretic peptide (BNP) (protein / peptide) levels, pH, pulmonary fluid status, and blood electrolytes (K+, Ca++, Na+, etc.).

[0098] Hemodynamic activity of a patient's heart may include one or more hemodynamic pressures that can be monitored (e.g., using various sensors) from locations within or around the patient's heart and / or within or around the patient's body (e.g., externally). Using such monitored hemodynamic pressures of the patient's heart, certain metrics can be determined and collected (e.g., for analysis). For example, the following hemodynamic metrics can be determined and collected using hemodynamic pressures of the patient's heart (e.g., using Medtronic OptiVol Fluid StatusMonitoring): mean arterial pressure, diastolic pressure, systolic pressure, flow velocity, pressure drop, pulmonary artery pressure, pulmonary capillary wedge pressure, right ventricular systolic pressure, right ventricular diastolic pressure, changes in tissue or blood oxygen saturation, changes in heart sound amplitude or timing, changes in intrathoracic impedance (e.g., Medtronic OptiVol Fluid StatusMonitoring), changes in intracardiac impedance, heart sounds, lung sounds, tissue perfusion, intracardiac pressure, pulmonary venous pressure, cardiac imaging, shear stress, partial pressure of oxygen, etc.

[0099] The collected data 202 can be analyzed to detect and / or determine cardiac events or conditions 204. For example, monitored physiological parameters may indicate arrhythmias, such as high heart rate or tachycardia (e.g., sinus tachycardia, VT / VF, SVT, AF, AV nodal reentrant tachycardia (AVNRT), AV reentrant tachycardia, junctional tachycardia, dual tachycardia, etc.), or heart failure breakdown. For example, methods for detecting and / or determining specific cardiac events or conditions have been disclosed in, for example, U.S. Patent Application Publication No. 2008 / 0269819A1, the entire contents of which are incorporated herein by reference. In at least one embodiment, the detected cardiac event or condition may be a change, such as a decrease in parasympathetic or efferent activity of one or both of the AV nodal of the patient's heart or the nerves innervating the AV nodal. In at least one embodiment, the detected cardiac event or condition may be a state of cardiac inflammatory disease or autonomic imbalance.

[0100] Although Figure 7 The diagram illustrates an arrow extending from data collection 202 to cardiac event detection 204; however, the data collection 202 and cardiac event detection 204 processes can be performed concurrently, rather than sequentially or periodically. Furthermore, it should be understood that data collection 202 and / or cardiac event detection 204 can be performed during the remainder of method 200. In other words, during method 200, data collection 202 and cardiac event detection 204 can be ongoing and continuous.

[0101] If cardiac symptom 204 is detected, method 200 can determine whether the detected cardiac symptom can be treated with AV node stimulation 206. Determining whether AV node stimulation 206 can be used to treat the detected cardiac symptom can be based on multiple factors. For example, a table or its equivalent can be consulted to determine whether AV node stimulation 206 can be used to treat the detected cardiac symptom. In one embodiment, a lookup table can be used to list which cardiac symptom can be treated by AV node stimulation. Therefore, after cardiac symptom 204 is detected, a lookup table (e.g., via a computing device that can be implanted in a medical device) can be consulted to determine whether the cardiac symptom can be treated by AV node stimulation. Further, for example, various physiological data can be evaluated to determine whether AV node stimulation 206 is likely to be effective in treating the detected cardiac symptom.

[0102] If the detected cardiac condition cannot be treated with AV node stimulation 206, method 200 can proceed with other treatments 207 for the detected cardiac condition. For example, illustrative devices 10, 310 can deliver various pacing therapies, such as AV synchronization pacing, cardiac resynchronization therapy, left ventricular stimulation, etc., using left ventricular electrodes (e.g., puncture electrodes 42, 342) and atrial electrodes (e.g., non-puncture electrodes 22, 322, 24). Therefore, the illustrative devices and methods described herein can deliver AV node stimulation and conventional pacing therapy to a patient based on their cardiac condition. It can be described that AV node stimulation and cardiac pacing therapy can be used to “titrate” the patient’s heart rate.

[0103] If AV node stimulation 206 can be used to treat the detected cardiac condition, method 200 can assess whether AV node stimulation 206 can be used to treat the detected cardiac condition. Then, method 200 can evaluate AV node stimulation criteria 208 for treating the detected cardiac condition before and / or during (e.g., periodically) the delivery of AV node stimulation. For example, method 200 may include analyzing physiological parameters against AV node stimulation criteria and preventing the delivery of AV node stimulation if the criteria 208 are met.

[0104] In at least one embodiment, the AV node stimulation criterion assessment process 208 may include monitoring the patient's physiological parameters (e.g., the electrical activity of the patient's heart) and analyzing the monitored physiological parameters relative to the AV node stimulation criteria. Analyzing the monitored physiological parameters may include determining whether the patient's cardiac electrical activity indicates a ventricular arrhythmia (e.g., VT / VF), determining whether a neural electrode configured to deliver electrical stimulation to the AV node or the nerve innervating the AV node is displaced, and / or determining the presence of unrestricted sympathetic excitation (e.g., which may be indicated by an acceleration of the heart rate (e.g., shortening of the VV interval, AV interval, VT interval, etc.)). AV node stimulation may not be delivered or may be blocked in response to "real" VT / VF (e.g., rapid conduction of AT / AF). Additionally, in at least one embodiment, AV node stimulation may be delivered if rapidly conduction of AT / AF introduces or causes a rapid ventricular rate. Displacement of a neural electrode configured to deliver electrical stimulation to the AV node or the nerve innervating the AV node may result in the delivery of electrical stimulation into the ventricle (e.g., a sudden onset of electrical stimulation), which may lead to unintended VT. If the patient’s cardiac electrical activity indicates a ventricular arrhythmia or if a neural electrode configured to deliver electrical stimulation to the AV node or the nerve innervating the AV node is displaced, process 208 will prevent the delivery of AV node stimulation (e.g., method 200 will return to data collection 202).

[0105] One method for determining whether a neural electrode configured to deliver electrical stimulation to the AV node or the nerve innervating the AV node has shifted includes analyzing electrical activity monitored by the neural electrode or analyzing the effectiveness of the stimulation delivered by the neural electrode. For example, if the electrical signal morphology changes from an atrial innervation morphology to a ventricular morphology, the neural electrode may have shifted. Further, for example, if the AV interval monitored by the neural electrode increases, the neural electrode may have shifted. Even further, for example, if a threshold for the effectiveness of AV node stimulation increases (e.g., AV node stimulation must be increased to be effective) or if AV node stimulation becomes ineffective, the neural electrode may have shifted.

[0106] U.S. Patent No. 8,781,582, entitled “Vagus Nerve Stimulation,” published on July 14, 2014, describes various procedures including standard analysis of physiological parameters and prevention of AV node stimulation delivery if the standard is not met. This patent is incorporated herein by reference in its entirety.

[0107] If the detected cardiac symptom can be treated with AV node stimulation 206 and the criteria for AV node stimulation 208 have been met, AV node stimulation can be delivered to patient 210. AV node stimulation 210 can be delivered to the AV node, a region near the AV node, and the nerve innervating the AV node of the patient's heart. Specifically, the illustrative device described herein is configured to be implanted in the right atrium to position or be located within the Koch's triangle region of the right atrium to deliver treatment or sense neural activity to one or both of the AV node of the patient's heart or the nerve innervating the AV node. Thus, AV node stimulation can be delivered to a region within the Koch's triangle that includes one or both of the AV node or the nerve innervating the AV node. As described herein, in one or more embodiments, the actual physical placement of one or more neural electrodes may be in contact with or adjacent to the nerve innervating the AV node of the patient's heart, opposite the AV node itself.

[0108] 210AV node stimulation can be delivered to one or both of the AV node or the nerve innervating the AV node in many different ways. For example, AV node stimulation can be delivered in the form of bursts of electrical stimulation pulses with various parameters. Such parameters may include time (e.g., electrical stimulation may be delivered within a selected time period of each cardiac cycle), voltage (e.g., in the range of about 1 volt to about 8 volts), pulse frequency within the burst (e.g., in the range of about 1 Hz to about 150 Hz), pulse frequency (e.g., in the range of about 1 Hz to about 100 Hz in the case of continuous delivery for cardiac stimulation, otherwise, each burst may be synchronized with the cardiac cycle or P wave or R wave), pulse width of each pulse (e.g., in the range of about 0.05 milliseconds (ms) to about 1.5 ms), and the number of pulses per burst (e.g., in the range of about 3 pulses to about 20 pulses), etc. In at least one embodiment, the AV node stimulation is less than or equal to 8 volts, has a pulse width of less than or equal to 2.5 milliseconds, has a frequency of less than or equal to 60 Hz, and comprises less than or equal to 8 pulses. In at least one embodiment, AV node stimulation comprises eight pulses with a pulse width of 1.5 milliseconds, a frequency of 40 or 50 Hz, and a pulse duration of 160 milliseconds. Additionally, when delivered for reducing heart rate, AV node stimulation can be greater than or equal to 4 volts and less than or equal to 8 volts. Furthermore, when delivered for anti-inflammatory effects or functions, AV node stimulation can be less than or equal to 8 volts, less than or equal to 4 volts, etc. Furthermore, AV node stimulation can be cyclical (e.g., “on” and then “off”, etc.) to “unload” the nerve at certain times (e.g., periodically), thereby limiting, for example, any possibility of nerve overstimulation.

[0109] Furthermore, such as Figures 8A to 8BAs shown, the delivery of AV node stimulation 210 can be synchronized to the blanking period associated with the P wave or R wave within the electrical activity of the patient's heart. If electrical stimulation is delivered to one or both of the AV node or the nerve innervating the AV node during periods corresponding to various cardiac events, the electrical stimulation is likely to be most effective and least likely to introduce arrhythmias.

[0110] Figures 8A to 8B This is a timing diagram illustrating the delivery of AV node stimulation (e.g., electrical stimulation pulses) to one or both of the AV node or the nerve innervating the AV node, corresponding to various cardiac events. Specifically, as... Figure 8A As shown, an electrical AV node stimulation pulse 286 (e.g., a burst of impulse) can be delivered during a ventricular blanking interval 282 (also known as the ventricular blanking period or the blanking period associated with the R wave) that is associated with or occurs after a ventricular event 280 (e.g., a sensed R wave or pacing pulse). The blanking period 282 corresponds to the ventricular refractory period following the ventricular sensing or pacing event 280. By delivering the electrical stimulation pulse 286 during the ventricular blanking interval 282, the same electrodes used for sensing atrial activity and / or delivering atrial pacing pulses can be used to deliver electrical AV node stimulation. In this way, electrical AV node stimulation does not occur during the ventricular vulnerable period; thus avoiding the arrhythmogenic effects associated with stimulation during the vulnerable period. The ventricular vulnerable period can be a time within the cardiac cycle during which electrical stimulation may induce arrhythmias (e.g., ventricular tachyarrhythmias (VT / VF)). In other words, the heart may be most susceptible to VT / VF induction by stimulation during such a vulnerable period. Typically, the vulnerable period of the ventricle occurs during the T wave (e.g., from the middle to the end of the T wave). Prior to the vulnerable period is the refractory period, during which stimulation may not elicit arrhythmias (e.g., it may also correspond to the extinction period).

[0111] In addition, such as Figure 8B As shown, an electrical AV node stimulation pulse 296 is delivered during an atrial blanking interval 292 (also called the atrial blanking period or the blanking period associated with the P wave) that is associated with or occurs after an atrial event 290 (e.g., sensing of a P wave or pacing pulse). The blanking period 292 corresponds to the atrial refractory period following the atrial sensing or pacing event 290. By delivering the electrical AV node stimulation pulse 296 during the atrial blanking interval 292, the same electrode used for sensing atrial activity and / or delivering atrial pacing pulses can be used to deliver the electrical AV node stimulation. In this way, the electrical AV node stimulation can avoid occurring during atrial vulnerability periods (e.g., any atrial vulnerability period can be similar to a ventricular vulnerability period, except that it involves AF instead of VT / VF), thereby avoiding arrhythmogenic effects associated with stimulation during vulnerable periods. For example, when the electrode is positioned in the right atrium for delivering the electrical stimulation pulse 296, the same electrode can be used for sensing atrial signals and / or delivering atrial pacing pulses.

[0112] In one or more methods described herein, electrical AV node stimulation can be synchronized with a blanking period associated with either or both of the P wave and R wave in the electrical activity of the patient's heart. Furthermore, the delivery of electrical AV node stimulation can be adjusted for various reasons to change the synchronization of the electrical AV node stimulation delivery from one type of blanking period to another. For example, the delivery of electrical AV node stimulation can be synchronized with an atrial P wave and then changed to a ventricular R wave, or vice versa. In at least one embodiment, when the patient's heart is in atrial fibrillation, electrical AV node stimulation can be synchronized with a P wave in sinus rhythm (e.g., delivering electrical stimulation during an atrial blanking period) and switched / changed to be synchronized with an R wave (e.g., delivering electrical stimulation during a ventricular blanking period).

[0113] Furthermore, upon detection of QRS complexes, P waves, or any other physiological parameters, electrical AV node stimulation 210 can be delivered after a fixed delay (e.g., a programmable delay). As a result, when electrical AV node stimulation is synchronized with a cardiac event, it can be delivered during or after the cardiac event (e.g., after a fixed delay). Furthermore, the process described herein may also include checking for capture of cardiac tissue (e.g., relative to neural tissue) that has not occurred (e.g., by checking for the presence of an evoked response) or adjusting stimulation parameters to avoid capture of cardiac tissue. Further, the delay can be adaptive to optimize the efficacy of electrical AV node stimulation (e.g., various electrical AV node stimulation parameters can be adjusted). For example, the delay can be adjusted to find a delay that has the greatest impact on cardiac behavior. Moreover, in at least one embodiment, the delivery of AV node stimulation 210 can be synchronized with one or both of the AV node or the nerve innervating the AV node to the patient's respiratory cycle or a portion thereof.

[0114] In addition, it should be understood that the standard procedure 208 for AV nodal stimulation can occur periodically during the delivery of AV nodal stimulation 210, for example, to ensure that the delivery of AV nodal stimulation remains appropriate.

[0115] Method 200 may further include adjusting AV nodal stimulation 212 to, for example, increase the effectiveness of AV nodal stimulation, and may further include assessing AV nodal stimulation termination criteria 214 to, for example, determine whether AV nodal stimulation should continue to be delivered to the patient. In other words, method 200 may assess AV nodal stimulation termination criteria 214 and interrupt or stop AV nodal stimulation based on assessment 214. Procedures 210, 212, and 214 may be performed simultaneously or periodically. For example, method 200 may deliver AV nodal stimulation 210 simultaneously, adjust AV nodal stimulation 212 periodically, and continuously assess AV nodal stimulation termination criteria 214.

[0116] Adjusting the AV node stimulation 212 may, for example, include adjusting the number of pulses included in the stimulation pulse sequence, adjusting (e.g., increasing) that number, adjusting (e.g., increasing) the frequency of the pulse sequence, and / or adjusting (e.g., increasing) the amplitude of the stimulation pulses. Furthermore, if other neural electrodes are available for stimulating the AV node or the neural tissue innervating the AV node, different electrodes or combinations of electrodes may be selected to deliver the AV node stimulation. However, if adjusting each parameter of the AV node stimulation does not produce any effective result (e.g., an effective result could be a detected increase in the AV interval or VV interval), then method 200 may determine that adjustments have been exhausted.

[0117] Additionally, adjusting AV node stimulation 212 can utilize performance data recorded or monitored during AV node stimulation delivery. For example, during and / or after AV node stimulation 210 delivery, method 200 can record patient performance data (e.g., patient physiological parameters, including the patient's cardiac electrical activity) to assess the efficacy of AV node stimulation. Recording performance data may include recording the interval between R waves, the interval between P waves and QRS complexes, R wave morphology, ST segment, T wave morphology, hemodynamic changes, etc. Furthermore, certain parameters of AV node stimulation (e.g., voltage, amplitude, number of pulses per burst, burst frequency, pulse frequency, pulse width, etc.) can be adjusted within certain ranges, allowing performance data to be recorded for AV node stimulation delivered with various selected parameters (e.g., frequency, pulse frequency, pulse width, etc.) (resulting in data from multiple different sets of selected parameters).

[0118] Recorded performance data can be evaluated to determine whether AV node stimulation is effective and / or which parameters of AV node stimulation are most effective. For example, the interval between R waves, the interval between P waves and QRS complexes, R wave morphology, ventricular pressure, etc., corresponding to AV node stimulation (e.g., occurring during or immediately after AV node stimulation), can be compared to selected values. These selected values ​​can be historical values ​​recorded from the patient prior to AV node stimulation, standard baseline values ​​of healthy cardiac activity, etc. In at least one embodiment, this comparison can also identify various effects from pre-stimulation to post-stimulation, such as changes in heart rate (HR).

[0119] As a result of evaluating the recorded performance data, method 200 can determine whether AV nodal stimulation is effective and / or which parameters of AV nodal stimulation are most effective in treating patients (e.g., optimal timing). If a specific set of parameters for AV nodal stimulation is determined to be most effective in treating patients, these parameters can be stored, for example, in an IMD, so that the most effective AV nodal stimulation can be delivered to the patient at a later time. Furthermore, as a result, the IMD can save energy, for example, by not delivering ineffective AV nodal stimulation, by not continuously adjusting AV nodal stimulation to achieve effectiveness, by finding effective AV nodal stimulation to replace some higher-energy therapies, etc.

[0120] As described herein, method 200 may further include assessing AV node stimulation termination criteria 214. Assessing termination criteria 214 may include monitoring the patient's physiological parameters (e.g., the electrical activity of the patient's heart) and analyzing the monitored physiological parameters against the termination criteria. Analyzing the monitored physiological parameters may include determining whether the interval between R waves in the patient's cardiac electrical activity has increased, determining whether the interval between P waves and QRS complexes in the patient's cardiac electrical activity has increased, and determining whether the patient's cardiac electrical activity indicates a ventricular arrhythmia. If the interval between R waves in the patient's cardiac electrical activity has not increased (e.g., in response to AV node stimulation), if the interval between P waves and QRS complexes in the patient's cardiac electrical activity has not increased (e.g., in response to AV node stimulation), or if the patient's cardiac electrical activity indicates a ventricular arrhythmia, the assessment of termination criteria 214 may result in termination (e.g., interruption or cessation) of electrical stimulation delivery to the AV node and / or the neural tissue innervating the AV node (e.g., method 200 will return to data collection) 202. In other words, AV node stimulation can be interrupted or stopped based on the assessment of the termination criteria. Additionally, in one or more embodiments, AV junction stimulation may be stopped only for a selected time period after the expiration of the period during which AV junction stimulation can begin to be delivered again.

[0121] The techniques described in this disclosure, including those belonging to IMD 10, device 50, IMD 310, and / or various constituent components, can be implemented at least in part in hardware, software, firmware, or any combination thereof. For example, aspects of the techniques can be implemented within one or more processors embodied in a programmer, stimulator, image processing device, or other device, such as a physician or patient programmer, including one or more microprocessors, DSPs, ASICs, FPGAs, or any other equivalent integrated or discrete logic circuit systems, and any combination of such components. The terms “module,” “processor,” or “processing circuit system” generally refer to any circuit system, alone or in combination with other logic circuit systems, or any other equivalent circuit system.

[0122] Such hardware, software, and / or firmware may be implemented within the same device or in separate devices to support the various operations and functions described in this disclosure. Furthermore, any described unit, module, or component may be implemented together or individually as discrete but interoperable logical devices. Describing different features as modules or units is intended to highlight different functional aspects and does not necessarily imply that such modules or units must be implemented by separate hardware or software components. Rather, the functionality associated with one or more modules or units may be performed by separate hardware or software components, or integrated into common or separate hardware or software components.

[0123] When implemented in software, the functionality attributable to the systems, apparatus, and techniques described herein can be embodied in instructions on a computer-readable medium such as RAM, ROM, NVRAM, EEPROM, flash memory, magnetic data storage media, optical data storage media, etc. The instructions can be executed by a processing circuit system and / or one or more processors to support one or more aspects of the functionality described herein.

[0124] For all purposes, all references and publications cited herein are expressly incorporated herein by reference in their entirety, unless any incorporated aspect directly contradicts this disclosure.

[0125] Unless otherwise stated, all scientific and technical terms used herein have the meanings commonly used in the art. The definitions provided herein are intended to facilitate understanding of certain terms frequently used herein and are not intended to limit the scope of this disclosure.

[0126] Unless otherwise stated, all figures used in the specification and claims to indicate the size, quantity, and physical properties of features are to be understood as being modified by the terms “complete” or “about”. Therefore, unless indicated to the contrary, the numerical parameters shown in the foregoing specification and appended claims are approximations that may vary depending on the desired properties sought by those skilled in the art using the teachings disclosed herein or, for example, within typical ranges of experimental error.

[0127] The numerical ranges listed by endpoints include all numbers included within the range (e.g., 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, and 5) and any range within the range. In this document, the terms "at most" or "not greater than" a number (e.g., at most 50) include that number (e.g., 50), and the terms "not less than" a number (e.g., not less than 5) include that number (e.g., 5).

[0128] The terms “link” or “connection” refer to components being directly connected to each other (in direct contact with each other) or indirectly connected (having one or more components between two components and connecting them). Both terms can be modified by “operationally” and “operably”, and they are used interchangeably to describe a link or connection configured to allow components to interact to perform at least some functions (e.g., a first medical device can be operably linked to another medical device to send or receive information in the form of data).

[0129] Orientation-related terms, such as “top,” “bottom,” “side,” and “end,” are used to describe the relative positioning of components and do not imply limitation on the orientation of the embodiments under consideration. For example, embodiments described as having a “top” and a “bottom” also include embodiments in which they can rotate in various directions, unless otherwise clearly indicated by the content.

[0130] The references to "one embodiment," "an embodiment," "certain embodiments," or "some embodiments," etc., mean that a particular feature, configuration, composition, or characteristic described in connection with the embodiment is included in at least one embodiment of this disclosure. Therefore, the appearance of these phrases in various places throughout the text does not necessarily refer to the same embodiment of this disclosure. Furthermore, in one or more embodiments, particular features, configurations, compositions, or characteristics may be combined in any suitable manner.

[0131] As used in this specification and the appended claims, unless otherwise expressly stated herein, the singular forms “a,” “an,” and “the” include embodiments having multiple referents. Unless otherwise expressly stated herein, as used in this specification and the appended claims, the term “or” is generally used in its sense to include “and / or.”

[0132] As used in this article, words such as “have,” “possess,” “include,” and “contain” are used in their open-ended sense and generally refer to “including but not limited to.” It will be understood that phrases such as “consistent with…” and “comprises from…” are included within words such as “contains.”

[0133] The term "and / or" refers to one or all of the listed elements or a combination of at least two of the listed elements. The phrases "at least one," "containing at least one," and "one or more" following the list refer to any one of the items in the list and any combination of two or more items in the list.

[0134] Explanatory aspects

[0135] Aspect 1: An implantable medical device comprising:

[0136] Multiple electrodes, including at least one neural electrode, the at least one neural electrode being capable of being implanted in the Koch triangle region of the right atrium to deliver therapy to or sense neural activity in the AV node of the patient’s heart or the nerve innervating the AV node.

[0137] A therapy delivery circuit, operatively coupled to multiple electrodes to deliver therapy to a patient’s heart;

[0138] A sensing circuit, operatively coupled to the plurality of electrodes, for sensing the electrical activity of the patient's heart; and

[0139] A computing device comprising processing circuitry operatively coupled to the therapy delivery circuitry and the sensing circuitry, the computing device being configured to deliver electrical stimulation to one or both of the AV node or the nerve innervating the AV node using the at least one neural electrode.

[0140] Aspect 2: A method comprising:

[0141] Provided are multiple electrodes, the multiple electrodes including at least one neural electrode, the at least one neural electrode being capable of being implanted in the Koch triangle region of the right atrium to deliver therapy to or sense neural activity in one or both of the AV node of the patient's heart or the nerve innervating the AV node; and

[0142] Electrical stimulation is delivered to one or both of the AV node or the nerve innervating the AV node using the at least one neural electrode.

[0143] Aspect 3: The method or apparatus according to any one of Aspects 1 to 2, wherein delivering electrical stimulation to one or both of the AV node or the nerve innervating the AV node using the at least one neural electrode comprises delivering electrical stimulation to an area at 65 to 125 degrees relative to the vertical axis passing through the coronary sinus ostium when viewed from a right anterior oblique 30-degree angle.

[0144] Aspect 4: The method or apparatus according to any one of Aspects 1 to 3, wherein delivering electrical stimulation to one or both of the AV node or the nerve innervating the AV node using the at least one neural electrode comprises delivering electrical stimulation to a region 8 to 16 millimeters from the coronary sinus ostium.

[0145] Aspect 5: The method or apparatus according to any one of Aspects 1 to 4, wherein the at least one neural electrode is coupled without leads to a distal region of a housing, the housing encapsulating a therapy delivery circuit, a sensing circuit, and a computing device.

[0146] Aspect 6: The method or apparatus according to any one of Aspects 1 to 5, wherein the electrical stimulation is less than or equal to 8 volts, has a pulse width of less than or equal to 2.5 milliseconds, has a frequency of less than or equal to 60 Hz, and comprises less than or equal to 8 pulses.

[0147] Aspect 7: The method or apparatus according to any one of Aspects 1 to 6, wherein the computing device is further configured to perform or the method further comprises sensing neural activity of one or both of the AV node of the patient's heart or the nerve innervating the AV node using the at least one neural electrode.

[0148] Aspect 8: The method or apparatus according to aspect 7, wherein the computing device is further configured to perform, or the method further comprises:

[0149] The parasympathetic nervous system activity is monitored using the at least one neural electrode to monitor the neural activity of one or both of the AV nodes of the patient's heart or the nerves innervating the AV nodes; and

[0150] In response to the detected parasympathetic activity, electrical stimulation is initiated using at least one neural electrode to deliver electrical stimulation to one or both of the AV node or the nerve innervating the AV node.

[0151] Aspect 9: The method or apparatus according to aspect 7, wherein the computing device is further configured to perform, or the method further comprises:

[0152] The at least one neural electrode is used to monitor the efferent activity of one or both of the AV node of the patient's heart or the nerve innervating the AV node; and

[0153] In response to the detected efferent activity, electrical stimulation is initiated using the at least one neural electrode to deliver electrical stimulation to one or both of the AV node or the nerve innervating the AV node.

[0154] Aspect 10: The method or apparatus according to any one of aspects 1 to 9, wherein the computing device is further configured to perform or the method further comprises, in response to the detection of supraventricular tachycardia, initiating the delivery of electrical stimulation to one or both of the at least one neural electrode to the AV node or the nerve innervating the AV node.

[0155] Aspect 11: The method or apparatus according to any one of Aspects 1 to 10, wherein the computing device is further configured to perform or the method further comprises, in response to detecting a cardiac inflammatory state or autonomic imbalance, initiating the delivery of electrical stimulation to one or both of the at least one neural electrode to the AV node or the nerve innervating the AV node.

[0156] Aspect 12: The method or apparatus according to aspect 11, wherein the computing device is further configured to perform, or the method further comprises:

[0157] The patient's heart electrical activity was monitored using the plurality of electrodes; and

[0158] The monitored electrical activity is used to detect one or both of cardiac inflammatory state and autonomic imbalance.

[0159] Aspect 13: The method or apparatus according to any one of aspects 1 to 12, wherein the computing device is further configured to perform, or the method further comprises:

[0160] The patient's cardiac depolarization electrical activity was monitored using the at least one neural electrode; and

[0161] Based on the monitored cardiac depolarization electrical activity, during the refractory period, electrical stimulation is delivered to one or both of the AV node or the nerve innervating the AV node using the at least one neural electrode.

[0162] Aspect 14: The method or apparatus according to any one of Aspects 1 to 14, wherein the computing device is further configured to perform or the method further comprises initiating electrical stimulation to one or both of the AV node or the nerve innervating the AV node using the at least one neural electrode to reduce the ventricular rate of the patient.

[0163] Aspect 15: The method or apparatus according to any one of Aspects 1 to 14, wherein the plurality of electrodes further comprises an atrial electrode capable of being implanted from the Koch triangle region of the right atrium to deliver cardiac therapy to the myocardium of the patient's atrium or to sense electrical activity in the myocardium of the patient's atrium, wherein the computing device is further configured to perform or the method further comprises delivering cardiac pacing therapy to the patient's heart using the atrial electrode.

[0164] Aspect 16: The method or apparatus according to any one of Aspects 1 to 15, wherein the at least one neural electrode is configured to deliver cardiac therapy to the myocardium of the patient's atrium or to sense electrical activity in the myocardium of the patient's atrium, wherein the computing device is further configured to perform or the method further comprises delivering cardiac pacing therapy to the patient's heart using the at least one neural electrode.

[0165] Aspect 17: The method or apparatus according to any one of Aspects 1 to 16, wherein the computing device is further configured to perform or the method further comprises, in response to a monitored heart rate, interrupting the delivery of any electrical stimulation to one or both of the at least one neural electrode to the AV node or the nerve innervating the AV node.

[0166] Aspect 18: The method or apparatus according to any one of Aspects 1 to 17, wherein the plurality of electrodes further comprises ventricular electrodes capable of being implanted through the right atrial endocardium and central fibrous body from the Koch's triangle region of the right atrium to deliver cardiac therapy to the basal region, septal region, or basal-septal region of the left ventricular myocardium of the patient's heart, or to sense electrical activity in the basal region, septal region, or basal-septal region of the left ventricular myocardium of the patient's heart.

[0167] The computing device is also configured to perform, or the method further includes, initiating the delivery of cardiac pacing therapy to the patient's heart using the ventricular electrodes.

[0168] Aspect 19: The method or apparatus according to aspect 18, wherein the cardiac pacing therapy comprises antitachycardia pacing.

[0169] This disclosure has been provided with reference to illustrative embodiments and aspects and is not intended to be interpreted in a limiting sense. As previously described, those skilled in the art will recognize that various other illustrative applications can utilize the beneficial features of the devices and methods described herein using the techniques described herein. Various modifications to the illustrative embodiments and aspects, as well as additional embodiments and aspects of this disclosure, will be apparent upon reference to this specification.

Claims

1. An implantable medical device comprising: Multiple electrodes, including at least one neural electrode, which is implantable in the Koch triangle region of the right atrium to deliver therapy or sense neural activity to one or both of the AV node of the patient’s heart or the nerve innervating the AV node. A therapy delivery circuit, operatively coupled to the plurality of electrodes to deliver therapy to the patient's heart; A sensing circuit operatively coupled to the plurality of electrodes to sense the electrical activity of the patient's heart; as well as A computing device comprising processing circuitry operatively coupled to the therapy delivery circuitry and the sensing circuitry, the computing device being configured to deliver electrical stimulation to one or both of the AV node or the nerve innervating the AV node using the at least one neural electrode.

2. The apparatus of claim 1, wherein delivering electrical stimulation to one or both of the AV node or the nerve innervating the AV node using the at least one neural electrode comprises delivering electrical stimulation to an area at 65 to 125 degrees relative to the vertical axis passing through the coronary sinus ostium when viewed from a right anterior oblique 30-degree angle.

3. The apparatus of claim 1, wherein delivering electrical stimulation to one or both of the AV node or the nerve innervating the AV node using the at least one neural electrode comprises delivering electrical stimulation to an area 8 to 16 millimeters from the coronary sinus ostium.

4. The device of claim 1, further comprising a housing extending from a proximal region to a distal region, wherein the at least one neural electrode is leadlessly coupled to the distal region of the housing, wherein the therapy delivery circuitry, the sensing circuitry, and the computing device are encapsulated within the housing.

5. The apparatus of claim 1, wherein the electrical stimulation is less than or equal to 8 volts, has a pulse width of less than or equal to 2.5 milliseconds, has a frequency of less than or equal to 60 Hz, and comprises less than or equal to 8 pulses.

6. The apparatus of claim 1, wherein the computing device is further configured to sense neural activity of one or both of the AV node of the patient's heart or the nerve innervating the AV node using the at least one neural electrode.

7. The apparatus of claim 6, wherein the computing device is further configured to: The parasympathetic nervous system activity is monitored using the at least one neural electrode to monitor the neural activity of one or both of the AV nodes of the patient's heart or the nerves innervating the AV nodes; and In response to detected parasympathetic activity, electrical stimulation is delivered to one or both of the AV node or the nerve innervating the AV node using the at least one neural electrode.

8. The apparatus of claim 6, wherein the computing device is further configured to: The at least one neural electrode is used to monitor the efferent activity of one or both of the nerve activity of the AV node of the patient's heart or the nerve innervating the AV node; and In response to the detected efferent activity, electrical stimulation is initiated using the at least one neural electrode to deliver electrical stimulation to one or both of the AV node or the nerve innervating the AV node.

9. The apparatus according to any one of claims 1-8, wherein the computing device is further configured to, in response to the detection of supraventricular tachycardia, initiate the delivery of electrical stimulation to one or both of the AV node or the nerve innervating the AV node using the at least one neural electrode.

10. The apparatus according to any one of claims 1-8, wherein the computing device is further configured to, in response to the detection of a cardiac inflammatory state or autonomic imbalance, initiate the delivery of electrical stimulation to one or both of the at least one neural electrode to the AV node or the nerve innervating the AV node.

11. The apparatus of claim 10, wherein the computing device is further configured to: The patient's heart electrical activity was monitored using the plurality of electrodes; and The monitored electrical activity is used to detect one or both of cardiac inflammatory status and autonomic imbalance.

12. The apparatus according to any one of claims 1-8, wherein the computing device is further configured to: The patient's cardiac depolarization electrical activity was monitored using the at least one neural electrode; and Based on the monitored cardiac depolarization electrical activity, during the refractory period, electrical stimulation is delivered to one or both of the AV node or the nerve innervating the AV node using the at least one neural electrode.

13. The apparatus according to any one of claims 1-8, wherein the computing device is further configured to initiate the delivery of electrical stimulation to one or both of the AV node or the nerve innervating the AV node using the at least one neural electrode to reduce the ventricular rate of the patient.

14. The apparatus according to any one of claims 1-8, wherein the computing device is further configured to, in response to a monitored heart rate, interrupt the delivery of any electrical stimulation to one or both of the at least one neural electrode to the AV node or the nerve innervating the AV node.

15. The device according to any one of claims 1-8, wherein the plurality of electrodes further comprises an atrial electrode capable of being implanted from the Koch triangle region of the right atrium to deliver cardiac therapy to the myocardium of the patient's atrium or to sense electrical activity in the myocardium of the patient's atrium. The computing device is also configured to deliver cardiac pacing therapy to the patient's heart using the atrial electrodes.

16. The apparatus according to any one of claims 1-8, wherein the at least one neural electrode is configured to deliver cardiac therapy to the myocardium of the patient's atrium or to sense electrical activity in the myocardium of the patient's atrium. The computing device is also configured to deliver cardiac pacing therapy to the patient's heart using the at least one neural electrode.

17. The device according to any one of claims 1-8, wherein the plurality of electrodes further comprises ventricular electrodes capable of being implanted through the right atrial endocardium and central fibrous body from the Koch's triangle region of the right atrium to deliver cardiac therapy to the basal region, septal region, or baso-septal region of the left ventricular myocardium of the patient's heart, or to sense electrical activity in the basal region, septal region, or baso-septal region of the left ventricular myocardium of the patient's heart. The computing device is also configured to deliver cardiac pacing therapy to the patient's heart using the ventricular electrodes.

18. The device of claim 17, wherein the cardiac pacing therapy comprises antitachycardia pacing.

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