AV-synchronized VFA cardiac therapy

Abstract

The present disclosure relates to AV synchronized VFA cardiac therapy. VfA cardiac therapy uses an implantable medical device or system. The implantable medical device comprises a tissue puncture electrode, and the tissue puncture electrode penetrates through the right atrium endocardium and the central fiber body from the Koch triangular area of the right atrium to be implanted into the basal area and / or the diaphragm area of the left ventricular myocardium of the heart of the patient. The device may include a right atrial electrode, a right atrial motion detector, or both. The device may be completely implanted within the patient's heart, or one or more leads may be used to implant the electrodes into the patient's heart. The device may be used to provide cardiac treatments, including single or multi-chamber pacing, atrioventricular synchronous pacing, asynchronous pacing, triggered pacing, cardiac resynchronous pacing, or tachycardia-related treatments. Separate medical devices may be used to provide some functionality for cardiac therapy, such as sensing, pacing, or shock therapy.

Description

This application is a divisional application of a patent application for "AV Synchronous VFA Cardiac Therapy" with an international filing date of March 22, 2019, an international application number of PCT / US2019 / 023636, and a national stage entry application number in China of 201980021138.0.

[0001] This application claims the benefit of U.S. Provisional Application Serial No. 62 / 647,426, filed on March 23, 2018, which is hereby incorporated by reference in its entirety.

[0002] The present disclosure relates to implantable medical devices, systems, and methods. In particular, the present disclosure relates to implantable medical devices, systems, and methods for ventricle-from-atrium (VfA) cardiac therapy, including single-chamber or multi-chamber pacing (e.g., dual-chamber or triple-chamber pacing), atrioventricular (AV) synchronous pacing, asynchronous pacing, triggered pacing, cardiac resynchronization pacing, or tachycardia-related therapy.

[0003] The cardiac conduction system includes the sinoatrial (SA) node, the atrioventricular (AV) node, the bundle of His, the bundle branches, and the Purkinje fibers. The heartbeat is initiated in the SA node, which can be described as the heart's natural "pacemaker." Electrical impulses initiated by the SA node cause the atrial myocardium to contract. The signal is conducted to the ventricles via the AV node, which inherently delays conduction to allow the atria to stop contracting before the ventricles begin to contract, thereby providing proper AV synchronization. The electrical impulse is conducted from the AV node to the ventricular myocardium via the bundle of His, the bundle branches, and the Purkinje fibers.

[0004] Patients with conduction system abnormalities (such as AV node conduction defects or SA node dysfunction) may receive an implantable medical device (IMD), such as a pacemaker, to restore a more normal heart rhythm and AV synchronization. Some types of IMDs (such as cardiac pacemakers, implantable cardioverter defibrillators (ICDs), or cardiac resynchronization therapy (CRT) devices) provide therapeutic electrical stimulation to a patient's heart via one or more implantable endocardial, epicardial, or coronary vein leads positioned in or near the heart. Therapeutic electrical stimulation can be delivered to the heart in the form of pulses or shocks for pacing, cardioversion, or defibrillation. In some cases, the IMD can sense the intrinsic depolarization of the heart and control the delivery of therapeutic stimulation to the heart based on that sensing.

[0005] In addressing cardiac conditions such as ventricular asynchrony that may occur within a patient, delivering therapeutic electrical stimulation to the heart can be useful. Ventricular asynchrony can be described as a lack of synchronization or a difference in the contraction timing between different ventricles of the heart. A significant difference in contraction timing can reduce cardiac efficiency. Cardiac Resynchronization Therapy (CRT) delivered by an IMD can enhance cardiac output by resynchronizing the electromechanical activity of the ventricles of the heart. Since CRT paces the right atrium, right ventricle, and left ventricle, CRT is sometimes referred to as "biventricular pacing".

[0006] In addition to, for example, cardiac pacing from an ICD, cardiac arrhythmias can be treated by delivering shock therapy to cardiovert or defibrillate the heart. The ICD can sense the patient's cardiac rhythm and classify the rhythm according to an arrhythmia detection protocol to facilitate the detection of the onset of tachycardia or fibrillation. Detected arrhythmias can include ventricular tachycardia (VT), fast ventricular tachycardia (FVT), ventricular fibrillation (VF), atrial tachycardia (AT), and atrial fibrillation (AF). Anti-tachycardia pacing (ATP) is a painless treatment that can be used to treat ventricular tachycardia (VT) to substantially terminate many monomorphic rapid rhythms. Although ATP is painless, ATP may not deliver an effective treatment for all types of VT. For example, ATP may be less effective for polymorphic VT with various morphologies. Polymorphic VT and ventricular fibrillation (VF) can be more life-threatening and may require more rapid treatment by electric shock.

[0007] Biventricular medical devices are available that include a transvenous atrial lead and a transvenous ventricular lead. The transvenous atrial lead carries an electrode that can be placed in the right atrium, and the transvenous ventricular lead carries an electrode that can be placed in the right ventricle via the right atrium. Biventricular medical devices are typically implanted in a subcutaneous pocket themselves, and the transvenous leads tunnel to the subcutaneous pocket. Biventricular medical devices can sense atrial electrical signals as well as ventricular electrical signals and can provide both atrial pacing and ventricular pacing as needed to promote a normal cardiac rhythm and AV synchronization. Some biventricular medical devices can treat both atrial and ventricular arrhythmias.

[0008] Intracardiac medical devices, such as leadless pacemakers, have been introduced or proposed to be fully implanted within a patient's heart, thereby eliminating the need for transvenous leads. A leadless pacemaker can include one or more electrodes on its outer housing to deliver therapeutic electrical signals and / or sense the intrinsic depolarization of the heart. Intracardiac medical devices can provide cardiac therapy functions (such as sensing and pacing) within a single chamber of the patient's heart. Single-chamber intracardiac devices can also treat atrial arrhythmias or ventricular arrhythmias or atrial fibrillation or ventricular fibrillation. Some leadless pacemakers are not intracardiac and can be located outside the heart and, in some examples, can be anchored to the wall of the heart via a fixation mechanism.

[0009] In some patients, a single-chamber device may adequately address the patient's needs. However, a single-chamber device that is only capable of single-chamber sensing and therapy may not fully address cardiac conduction diseases or abnormalities in all patients, e.g., those patients with some form of AV asynchrony or tachycardia. In some cases, in addition to ICD functionality, dual-chamber sensing and / or pacing functionality may be used to restore a more normal cardiac rhythm. SUMMARY OF THE INVENTION

[0010] Various embodiments of the present disclosure relate to implantable medical devices, systems, and methods for VfA cardiac therapy, including single-chamber or multi-chamber pacing (e.g., dual-chamber or triple-chamber pacing), atrioventricular synchronous pacing, asynchronous pacing, triggered pacing, cardiac resynchronization pacing, or tachycardia-related therapy. A tissue piercing electrode is implanted in the basal region and / or septal region of the left ventricular myocardium of a patient's heart through the Koch triangle region of the right atrium, through the right atrial endocardium and the central fibrous body, for facilitating VfA cardiac therapy.

[0011] In one aspect, the present disclosure relates to an implantable medical device including a plurality of electrodes. The plurality of electrodes includes a tissue piercing electrode that is implantable through the Koch triangle region of the right atrium, through the right atrial endocardium and the central fibrous body, for delivering cardiac therapy to the left ventricle and sensing at least one of the electrical activity of the left ventricle in the basal region and / or septal region of the left ventricular myocardium of a patient's heart. The plurality of electrodes further includes a right atrial electrode that is positionable within the right atrium for delivering cardiac therapy and sensing at least one of the electrical activity of the right atrium of a patient's heart. The implantable medical device further includes: a therapy delivery circuit operatively coupled to the plurality of electrodes for delivering cardiac therapy to a patient's heart; and a sensing circuit operatively coupled to the plurality of electrodes for sensing the electrical activity of a patient's heart. The implantable medical device further includes a controller including a processing circuitry operatively coupled to the therapy delivery circuit and the sensing circuit. The controller is configured to: monitor the electrical activity of the right atrium using the right atrial electrode; and deliver atrioventricular synchronous pacing based on the monitored electrical activity of the right atrium using at least the tissue piercing electrode implanted in the basal region and / or septal region of the left ventricular myocardium of a patient's heart through the Koch triangle region of the right atrium, through the right atrial endocardium and the central fibrous body, for pacing one or both ventricles.

[0012] In another aspect, the present disclosure relates to a method comprising: monitoring activity of a right atrium of a patient's heart using a right atrial electrode or a right atrial motion detector; and delivering atrioventricular synchronous pacing based on the monitored electrical activity of the right atrium using at least a tissue piercing electrode implanted in a basal region and / or a septal region of a left ventricular myocardium of the patient's heart through a Koch triangle region of the right atrium, through a right atrial endocardium, and through a central fibrous body, the delivering atrioventricular synchronous pacing comprising pacing one or both ventricles using at least the at least one tissue piercing electrode.

[0013] In another aspect, the present disclosure relates to an implantable medical device. The implantable medical device includes a housing extending from a proximal end region to a distal end region. The device further includes a plurality of electrodes. The plurality of electrodes includes a tissue piercing electrode that is leadless coupled to the distal end region of the housing and is implantable through a Koch triangle region of the right atrium, through a right atrial endocardium, and through a central fibrous body for delivering cardiac therapy to or sensing electrical activity of a left ventricle in a basal region and / or a septal region of a left ventricular myocardium of the patient's heart. The plurality of electrodes further includes a right atrial electrode that is leadless coupled to the housing and is positionable within the right atrium for delivering cardiac therapy to or sensing electrical activity of a right atrium of the patient's heart. The implantable medical device further includes: a therapy delivery circuit within the housing that is operably coupled to the plurality of electrodes for delivering cardiac therapy to the patient's heart; and a sensing circuit within the housing that is operably coupled to the plurality of electrodes for sensing electrical activity of the patient's heart. The implantable medical device further includes a controller that includes processing circuitry within the housing operably coupled to the therapy delivery circuit and the sensing circuit. The controller is configured to: monitor electrical activity of the right atrium using the right atrial electrode; and deliver atrioventricular synchronous pacing based on the monitored electrical activity of the right atrium using at least the tissue piercing electrode implanted in a basal region and / or a septal region of a left ventricular myocardium of the patient's heart through a Koch triangle region of the right atrium, through a right atrial endocardium, and through a central fibrous body for pacing one or both ventricles.

[0014] In another aspect, the present disclosure relates to an implantable medical device that includes a plurality of electrodes. The plurality of electrodes includes a tissue piercing electrode that is implantable through the endocardium of the right atrium and the central fibrous body from the Koch triangle region of the right atrium for delivering cardiac therapy to the left ventricle and / or sensing at least one of the electrical activity of the left ventricle in a basal region and / or a septal region of the left ventricular myocardium of a patient's heart. The tissue piercing electrode further includes a right atrial motion detector that is positionable within the right atrium for sensing mechanical activity of the right atrium of the patient's heart. The implantable medical device further includes a therapy delivery circuit that is operably coupled to the plurality of electrodes for delivering cardiac therapy to the patient's heart; and a sensing circuit that is operably coupled to the plurality of electrodes for sensing electrical activity of the patient's heart. The implantable medical device further includes a controller that includes a processing circuitry operably coupled to the therapy delivery circuit and the sensing circuit. The controller is configured to: monitor mechanical activity of the right atrium using the right atrial motion detector; and deliver atrioventricular synchronous pacing based on the monitored mechanical activity of the right atrium using at least the tissue piercing electrode implanted through the endocardium of the right atrium and the central fibrous body from the Koch triangle region of the right atrium into the basal region and / or the septal region of the left ventricular myocardium of the patient's heart to pace one or both ventricles.

[0015] In another aspect, the present disclosure relates to an implantable medical device including a plurality of electrodes. The plurality of electrodes includes a tissue piercing electrode that is implantable through the right atrial endocardium and the central fibrous body from the Koch triangle region of the right atrium for delivering cardiac therapy and / or sensing electrical activity of the left ventricle in the basal region and / or septal region of the left ventricular myocardium of a patient's heart. The plurality of electrodes further includes a right atrial electrode that can be positioned within the right atrium for delivering cardiac therapy and / or sensing electrical activity of the right atrium of a patient's heart. The implantable medical device further includes: a therapy delivery circuit operably coupled to the plurality of electrodes for delivering cardiac therapy to a patient's heart; and a sensing circuit operably coupled to the plurality of electrodes for sensing electrical activity of a patient's heart. The implantable medical device further includes a controller including a processing circuitry operably coupled to the therapy delivery circuit and the sensing circuit. The controller is configured to perform at least one of the following: monitor electrical activity of the right atrium using the right atrial electrode; and monitor electrical activity of the left ventricle using the tissue piercing electrode implanted through the right atrial endocardium and the central fibrous body from the Koch triangle region of the right atrium in the basal region and / or septal region of the left ventricular myocardium of a patient's heart. The controller is further configured to deliver cardiac resynchronization pacing based on the monitored electrical activity using at least the tissue piercing electrode implanted through the right atrial endocardium and the central fibrous body from the Koch triangle region of the right atrium in the basal region and / or septal region of the left ventricular myocardium of a patient's heart to pace one or both ventricles.

[0016] In another aspect, the present disclosure relates to a method including at least one of the following: monitoring electrical activity of the right atrium of a patient's heart using a right atrial electrode; and monitoring electrical activity of the left ventricle using a tissue piercing electrode implanted through the right atrial endocardium and the central fibrous body from the Koch triangle region of the right atrium in the basal region and / or septal region of the left ventricular myocardium of a patient's heart. The method further includes delivering cardiac resynchronization pacing based on the monitored electrical activity using at least the tissue piercing electrode implanted through the right atrial endocardium and the central fibrous body from the Koch triangle region of the right atrium in the basal region and / or septal region of the left ventricular myocardium of a patient's heart, including pacing one or both ventricles.

[0017] In another aspect, the present disclosure relates to an implantable medical device that includes a housing extending from a proximal end region to a distal end region. The implantable medical device further includes a plurality of electrodes. The plurality of electrodes includes a tissue piercing electrode that is leadless and coupled to the distal end region of the housing and is implantable through the endocardium of the right atrium and the central fibrous body from the Koch triangle region of the right atrium for delivering cardiac therapy to the left ventricle or sensing electrical activity of the left ventricle in a basal region and / or a septal region of the left ventricular myocardium of a patient's heart. The plurality of electrodes further includes a right atrial electrode that is leadless and coupled to the housing and is positionable within the right atrium for delivering cardiac therapy to the right atrium of a patient's heart or sensing electrical activity of the right atrium of a patient's heart. The implantable medical device further includes: a therapy delivery circuit within the housing that is operably coupled to the plurality of electrodes for delivering cardiac therapy to a patient's heart; and a sensing circuit within the housing that is operably coupled to the plurality of electrodes for sensing electrical activity of a patient's heart. The implantable medical device further includes a controller that includes processing circuitry within the housing that is operably coupled to the therapy delivery circuit and the sensing circuit. The controller is configured to perform at least one of the following: monitor electrical activity of the right atrium using the right atrial electrode; and monitor electrical activity of the left ventricle using the tissue piercing electrode that is from the Koch triangle region of the right atrium through the endocardium of the right atrium and the central fibrous body in a basal region and / or a septal region of the left ventricular myocardium of a patient's heart. The controller is further configured to deliver cardiac resynchronization pacing based on the monitored electrical activity using at least the tissue piercing electrode that is implanted from the Koch triangle region of the right atrium through the endocardium of the right atrium and the central fibrous body in a basal region and / or a septal region of the left ventricular myocardium of a patient's heart to pace one or both ventricles.

[0018] In another aspect, the present disclosure relates to an implantable medical device including a plurality of electrodes. The plurality of electrodes includes a tissue piercing electrode that is implantable through the endocardium of the right atrium and the central fibrous body from the Koch triangle region of the right atrium for delivering cardiac therapy to the left ventricle and / or sensing at least one of the electrical activity of the left ventricle in the basal region and / or septal region of the left ventricular myocardium of a patient's heart. The plurality of electrodes further includes a right atrial motion detector that is positionable within the right atrium for sensing the mechanical activity of the right atrium of the patient's heart. The implantable medical device further includes: a therapy delivery circuit operably coupled to the plurality of electrodes for delivering cardiac therapy to the patient's heart; and a sensing circuit operably coupled to the plurality of electrodes for sensing the electrical activity of the patient's heart. The implantable medical device further includes a controller including a processing circuitry operably coupled to the therapy delivery circuit and the sensing circuit. The controller is configured to: monitor the mechanical activity of the right atrium using the right atrial motion detector; and deliver cardiac resynchronization pacing based on the monitored mechanical activity of the right atrium using at least the tissue piercing electrode implanted through the endocardium of the right atrium and the central fibrous body from the Koch triangle region of the right atrium in the basal region and / or septal region of the left ventricular myocardium of the patient's heart to pace one or both ventricles.

[0019] In another aspect, the present disclosure relates to an implantable medical device including a plurality of electrodes. The plurality of electrodes includes a tissue piercing electrode that is implantable through the endocardium of the right atrium and the central fibrous body from the Koch triangle region of the right atrium for delivering cardiac therapy to the left ventricle or sensing the electrical activity of the left ventricle. The plurality of electrodes further includes a right atrial electrode positionable within the right atrium for delivering cardiac therapy to the right atrium of the patient's heart or sensing the electrical activity of the right atrium of the patient's heart. The implantable medical device further includes: a therapy delivery circuit operably coupled to the plurality of electrodes for delivering cardiac therapy to the patient's heart; and a sensing circuit operably coupled to the plurality of electrodes for sensing the electrical activity of the patient's heart. The implantable medical device further includes a controller including a processing circuitry operably coupled to the therapy delivery circuit and the sensing circuit. The controller is configured to: monitor the electrical activity of the right atrium using the right atrial electrode; monitor the electrical activity of the left ventricle using the tissue piercing electrode implanted through the endocardium of the right atrium and the central fibrous body from the Koch triangle region of the right atrium in the basal region and / or septal region of the left ventricular myocardium of the patient's heart for sensing the electrical activity of the left ventricle in the basal region and / or septal region of the left ventricular myocardium; and deliver tachycardia therapy based on the monitored electrical activity of the right atrium and the left ventricle.

[0020] In another aspect, the present disclosure relates to a method that includes: monitoring electrical activity of a right atrium of a patient's heart using a right atrial electrode; monitoring electrical activity of a left ventricle of the patient's heart using a tissue piercing electrode that is implanted from a Koch triangle region of the right atrium through the right atrial endocardium and the central fibrous body into a basal region and / or a septal region of the left ventricular myocardium of the patient's heart to sense the electrical activity of the left ventricle in the basal region and / or the septal region of the left ventricular myocardium; and delivering tachycardia therapy based on the monitored electrical activity of the right atrium and the left ventricle.

[0021] In another aspect, the present disclosure relates to an implantable medical device that includes a plurality of electrodes. The plurality of electrodes includes a tissue piercing electrode that is implantable from a Koch triangle region of the right atrium through the right atrial endocardium and the central fibrous body for delivering cardiac therapy to or sensing electrical activity of a left ventricle in a basal region and / or a septal region of the left ventricular myocardium of a patient's heart. The plurality of electrodes further includes a right atrial electrode that can be positioned within the right atrium for delivering cardiac therapy to or sensing electrical activity of the right atrium of the patient's heart. The implantable medical device further includes: a therapy delivery circuit that is operably coupled to the plurality of electrodes for delivering cardiac therapy to the patient's heart; and a sensing circuit that is operably coupled to the plurality of electrodes for sensing electrical activity of the patient's heart. The implantable medical device further includes a controller that includes processing circuitry operably coupled to the therapy delivery circuit and the sensing circuit. The controller is configured to: monitor electrical activity of the right atrium using the right atrial electrode; monitor electrical activity of the left ventricle using the tissue piercing electrode that is implanted from a Koch triangle region of the right atrium through the right atrial endocardium and the central fibrous body into a basal region and / or a septal region of the left ventricular myocardium of the patient's heart to sense the electrical activity of the left ventricle; and determine tachycardia of the patient's heart based on the monitored electrical activity of the right atrium and the left ventricle.

[0022] In another aspect, the present disclosure relates to an implantable medical device that includes a plurality of electrodes. The plurality of electrodes includes a tissue piercing electrode that is implantable through the endocardium of the right atrium and the central fibrous body from the Koch triangle region of the right atrium for delivering cardiac therapy to the left ventricle or sensing electrical activity of the left ventricle in a basal region and / or a septal region of the left ventricular myocardium of a patient's heart. The plurality of electrodes further includes a right atrial electrode that is positionable within the right atrium for delivering cardiac therapy to the right atrium of a patient's heart or sensing electrical activity of the right atrium of a patient's heart. The implantable medical device further includes: a therapy delivery circuit operably coupled to the plurality of electrodes for delivering cardiac therapy to a patient's heart; and a sensing circuit operably coupled to the plurality of electrodes for sensing electrical activity of a patient's heart. The implantable medical device further includes a controller that includes a processing circuitry operably coupled to the therapy delivery circuit and the sensing circuit. The controller is configured to perform at least one of the following: delivering antitachycardia pacing therapy using the plurality of electrodes, and delivering shock therapy using a separate medical device.

[0023] The foregoing summary is not intended to describe every embodiment or every implementation of the present disclosure. A more complete understanding will become apparent and comprehensible by reference to the following detailed description, taken in conjunction with the accompanying drawings, and illustrative embodiments 1-56. In other words, these and various other features and advantages will become apparent by reading the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 is a conceptual diagram of an illustrative cardiac therapy system that includes an intracardiac medical device implanted in a patient's heart shown in cross-sectional view and a separate medical device positioned external to the patient's heart.

[0025] Figure 2 is Figure 1 an enlarged conceptual diagram of the intracardiac medical device and the anatomy of a patient's heart.

[0026] Figure 3 is a perspective view of an intracardiac medical device having a distal fixation and electrode assembly with a distal housing-based electrode implemented as a ring electrode. Figures 1 - 2 of the intracardiac medical device.

[0027] Figure 4 is Figures 1 - 3 a block diagram of exemplary circuitry that can be enclosed within the housing of an intracardiac medical device for providing functions and therapies described herein.

[0028] Figure 5 is Figures 1 - 4 a perspective view of another illustrative intracardiac medical device for use with an illustrative system and device such as

[0029] Figure 6 is a flowchart of an illustrative cardiac treatment method for use with illustrative systems and devices such as Figures 1 - 5 .

[0030] Figure 7 is a flowchart of an illustrative pacing treatment method for use with illustrative methods such as Figure 6 .

[0031] Figure 8 is a flowchart of another illustrative pacing treatment method for use with illustrative methods such as Figure 6 .

[0032] Figure 9 is a flowchart of an illustrative tachycardia-related method for use with illustrative systems and devices such as Figures 1 - 5 .

[0033] Figure 10 is a flowchart of an illustrative tachycardia determination method for use with illustrative methods such as Figure 9 .

[0034] Figure 11 is a flowchart of an illustrative tachycardia treatment determination method for use with illustrative methods such as Figure 10 .

[0035] Figure 12 is a flowchart of another illustrative antitachycardia method for use with illustrative systems and devices such as Figures 1 - 5 .

[0036] Figure 13 is a flowchart of an illustrative tachycardia treatment delivery method for use with illustrative methods such as Figure 12 .

[0037] Figure 14 is a flowchart of an illustrative shock treatment method for use with illustrative methods such as Figure 13 .

[0038] Figure 15 is a conceptual diagram of a heart of a patient showing a standard 17-segment view of the left ventricle with various electrode implantation positions for use with exemplary systems and devices such as Figures 1 - 5 .

[0039] Figures 16 - 18 is a conceptual diagram of an illustrative cardiac treatment system including a medical device that includes a lead having electrodes implanted in a patient's heart shown in cross-sectional view for use with illustrative methods such as Figures 6 - 14 orFigures 1 - 5 Electrodes for use with illustrative systems and devices.

[0040] Figure 19 Is a state diagram showing different illustrative modes for use with illustrative systems and devices such as Figures 1 - 5 and Figures 16 - 18 of illustrative systems and devices.

[0041] Figure 20 Is a diagram of an illustrative system including an electrode device, a display device, and a computing device for use with illustrative systems and devices such as Figures 1 - 5 and Figures 16 - 18 of illustrative systems and devices.

[0042] Figures 21 - 22 Is a diagram of an illustrative extracorporeal electrode device for measuring torso surface potential for use with illustrative systems and devices such as Figures 1 - 5 and Figures 16 - 18 of illustrative systems and devices.

[0043] Figure 23 Is a flowchart of an illustrative method for detecting atrial activity using an atrial motion detector for use with illustrative systems and devices such as Figures 1 - 5 and Figures 16 - 18 of illustrative systems and devices. Detailed Description

[0044] This disclosure relates to implantable medical devices, systems, and methods for VfA cardiac therapy, including single-chamber or multi-chamber pacing (e.g., dual-chamber or triple-chamber pacing), atrioventricular synchronous pacing, asynchronous pacing, triggered pacing, cardiac resynchronization pacing, or tachycardia-related therapy. Although this document refers to implantable medical devices such as pacemakers or ICDs, these methods and procedures can be used with any medical device, system, or method related to a patient's heart. Various other applications will be apparent to those skilled in the art who would benefit from this disclosure.

[0045] It may be beneficial to provide an implantable medical device without a transvenous lead (e.g., a leadless device). It may also be beneficial to provide an implantable medical device that can be used for various cardiac therapies such as single-chamber or multi-chamber pacing (e.g., dual-chamber or triple-chamber pacing), atrioventricular synchronous pacing, asynchronous pacing, triggered pacing, cardiac resynchronization pacing, or tachycardia-related therapy. Further, it may be beneficial to provide a system that can communicate with separate medical devices, e.g., for providing triggered pacing or shock therapy in certain cases of tachycardia.

[0046] The present disclosure provides an implantable medical device that includes a tissue piercing electrode and optionally includes a right atrial electrode and / or a right atrial motion detector. The tissue piercing electrode can be implanted in the basal region and / or the septal region of the left ventricular myocardium of a patient's heart by passing through the right atrial endocardium and the central fibrous body from the triangle of Koch region of the right atrium. In a leadless implantable medical device, the tissue piercing electrode can extend leadlessly from the distal end region of the device's housing, and the right atrial electrode can be coupled leadlessly to the housing (e.g., as part of the housing or positioned externally on the housing). The right atrial motion detector can be within the implantable medical device. In a leaded implantable medical device, one or more of the electrodes can be coupled to the housing using implantable leads. When the device is implanted, the electrodes can be used to sense electrical activity in one or more of the atria and / or ventricles of the patient's heart. The motion detector can be used to sense mechanical activity in one or more of the atria and / or ventricles of the patient's heart. Specifically, the activities of the right atrium and the left ventricle can be monitored, and optionally the activity of the right ventricle can be monitored. The electrodes can be used to deliver cardiac therapies such as single chamber pacing for atrial fibrillation, atrioventricular synchronous pacing for bradycardia, asynchronous pacing, triggered pacing, cardiac resynchronization pacing for treating ventricular dyssynchrony, anti-tachycardia pacing, or shock therapy. The shock therapy can be initiated by the implantable medical device. Separate medical devices (such as an extracorporeal ICD) can also be implanted, which can communicate operatively with the implantable medical device and can deliver a shock in response to a trigger (such as a signaling pulse provided by the device (e.g., a trigger, a signal, or a unique electrical pulse)).

[0047] Reference will now be made to the accompanying drawings, which depict one or more aspects described in the present disclosure. However, it will be understood that other aspects not depicted in the drawings will fall within the scope of the present disclosure. Like reference numerals in the drawings refer to like components, steps, etc. However, it will be understood that the use of a reference numeral to refer to an element in a given drawing is not intended to limit the element denoted by the same reference numeral in another drawing. Additionally, the use of different reference numerals to refer to elements in different drawings is not intended to indicate that the differently labeled elements cannot be the same or similar.

[0048] Although the present disclosure describes leadless and leaded implantable medical devices, reference will first be made to Figure 1, a conceptual diagram of a cardiac therapy system 2 including an intravascular medical device 10 that can be configured for single-chamber or dual-chamber therapy and implanted in a patient's heart 8 is shown. In some embodiments, the device 10 can be configured for single-chamber pacing and can, for example, switch between single-chamber and multi-chamber pacing (e.g., dual-chamber or triple-chamber pacing). As used herein, "intravascular" refers to a device configured to be fully implanted within a patient's heart, e.g., for providing cardiac therapy. The device 10 is shown implanted in the right atrium (RA) of the patient's heart 8 in a target implantation region 4. The device 10 can include one or more fixation members 20 that anchor the distal end of the device against the atrial endocardium in the target implantation region 4. The target implantation region 4 can be located between the His bundle 5 and the coronary sinus 3 and can be adjacent to the tricuspid valve 6. The device 10 can be described as an atrial-to-ventricular (VfA) device that can sense one or more ventricles (e.g., the right ventricle, the left ventricle, or both ventricles, depending on the circumstances) or provide therapy to one or more ventricles while being generally disposed in the right atrium. Specifically, the device 10 can include a tissue piercing electrode that can be implanted in the basal region and / or septal region of the left ventricular myocardium of the patient's heart by passing through the right atrial endocardium and the central fibrous body from the Koch triangle region of the right atrium.

[0049] The device 10 can be described as a leadless implantable medical device. As used herein, "leadless" means that the device does not have leads that extend outward from the patient's heart 8. In other words, a leadless device can have no leads that extend from outside the patient's heart to inside the patient's heart. Some leadless devices can be introduced via a vein, but once implanted, the device does not have or may not include any transvenous leads and can be configured to provide cardiac therapy without using any transvenous leads. When the housing of a leadless VfA device is positioned in the atrium, the device does not use leads in particular to operably connect to electrodes in the ventricle. The leadless electrodes can be coupled to the housing of the medical device without using leads between the electrodes and the housing.

[0050] The device 10 can include one or more dart electrodes 12 having a straight shaft that extends from the distal end region of the device 10, through the atrial myocardium and the central fibrous body, and into the ventricular myocardium 14 or along the ventricular septum without fully penetrating the ventricular endocardium or epicardial surface. That is, the dart electrode 12 can not pierce through the ventricular wall into the blood volume. The dart electrode 12 can carry an electrode at the distal end region of the shaft to position the electrode within the ventricular myocardium for sensing ventricular signals and delivering ventricular pulses (e.g., for depolarizing the left ventricle to initiate contraction of the left ventricle). In some examples, the electrode at the distal end region of the shaft is a cathode electrode that is provided for use in a bipolar electrode pair for pacing and sensing. Although in Figure 1The implantation region 4 is shown such that one or more electrodes of one or more dart electrodes 12 can be positioned in the ventricular myocardium, but it is recognized that devices having multiple aspects disclosed herein can be implanted in other locations 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 as applicable.

[0051] The cardiac therapy system 2 may also include a separate medical device 50 (schematically depicted in Figure 1 ), which can be positioned external to the patient's heart 8 (e.g., subcutaneously) and can be operably coupled to the patient's heart 8 for delivering cardiac therapy to the heart 8. In one example, the separate medical device 50 can be an extracorporeal ICD. In some embodiments, the extracorporeal ICD may include a defibrillation lead with defibrillation electrodes. A therapy vector can exist between the defibrillation electrodes on the defibrillation lead and the can electrode of the ICD. Further, one or more electrodes of the ICD can also be used to sense electrical signals regarding the patient's heart 8. The ICD can be configured to deliver shock therapy including one or more defibrillation or cardioversion shocks. For example, if an arrhythmia is sensed, the ICD can send a pulse via an electrical lead to shock the heart and restore its normal rhythm. In some examples, the ICD can deliver shock therapy without placing an electrical lead within the heart or directly attaching an electrical wire to the heart (subcutaneous ICD). Examples of extracorporeal, subcutaneous ICDs that can be used with the system 2 described herein can be described in U.S. Patent No. 9,278,229 (Reinke et al.) issued on March 8, 2016, which is incorporated herein by reference in its entirety.

[0052] In the case of shock therapy, e.g., a defibrillation shock provided by the defibrillation electrodes of the defibrillation lead, the separate medical device 50 (e.g., extracorporeal ICD) can include a control circuit that uses a therapy delivery circuit to generate a defibrillation shock having any of a plurality of waveform attributes including leading-edge voltage, slope, delivered energy, pulse phase, etc. The therapy delivery circuit can, for example, generate a monophasic, biphasic, or polyphasic waveform. Additionally, the therapy delivery circuit can generate defibrillation waveforms having different amounts of energy. For example, the therapy delivery circuit can generate a defibrillation waveform that delivers subcutaneous defibrillation energy totaling between approximately 60 - 80 joules (J).

[0053] The separate medical device 50 may include a sensing circuit. The sensing circuit may be configured to acquire electrical signals sensed via one or more combinations of electrodes and process the acquired signals. Components of the sensing circuit may be analog components, digital components, or a combination thereof. The sensing circuit may include, for example, one or more sensing amplifiers, filters, rectifiers, threshold detectors, analog-to-digital converters (ADCs), etc. The sensing circuit may convert the sensed signals to digital form and provide the digital signals to the control circuit for processing or analysis. For example, the sensing circuit may amplify signals from the sensing electrodes and the amplified signals may be converted to multi-bit digital signals by an ADC. The sensing circuit may also compare the processed signals with a threshold to detect the presence of atrial or ventricular depolarization (e.g., P wave or R wave) and indicate to the control circuit the presence of atrial depolarization (e.g., P wave) or ventricular depolarization (e.g., R wave).

[0054] The device 10 and the separate medical device 50 may cooperate to provide cardiac therapy to a patient's heart 8. For example, the device 10 and the separate medical device 50 may be used to detect tachycardia, monitor tachycardia, and / or provide tachycardia-related therapy. For example, the device 10 may communicate wirelessly with the separate medical device 50 to trigger shock therapy using the separate medical device 50. As used herein, "wirelessly" refers to an operative coupling or connection without the use of a metallic conductor between the device 10 and the separate medical device 50. In one example, the wireless communication may use a unique signaling or trigger electrical pulse provided by the device 10 that conducts through the patient's tissue and is detectable by the separate medical device 50. In another example, the wireless communication may use a communication interface (e.g., antenna) of the device 10 to provide electromagnetic radiation that propagates through the patient's tissue and is detectable, for example, using a communication interface (e.g., antenna) of the separate medical device 50.

[0055] Figure 2 is an enlarged conceptual view of the anatomy of the intracardiac medical device 10 and a patient's heart 8. The intracardiac device 10 may include a housing 30. The housing 30 may define a hermetically sealed internal cavity in which the internal components of the device 10 reside, such internal components as a sensing circuit, a therapy delivery circuit, a control circuit, a memory, a telemetry circuit, other optional sensors, and a power source, as generally described below Figure 4 The housing 30 may be formed of a conductive material, including titanium or a titanium alloy, stainless steel, MP35N (a non-magnetic nickel-cobalt-chromium-molybdenum alloy), a platinum alloy, or other biocompatible metal or metal alloy. In other examples, the housing 30 may be formed of a non-conductive material, including ceramic, glass, sapphire, silicone, polyurethane, epoxy resin, acetyl copolymer plastic, polyetheretherketone (PEEK), liquid crystal polymer, or other biocompatible polymer.

[0056] The housing 30 can be described as extending between a distal end region 32 and a proximal end region 34, being generally cylindrical in shape to facilitate catheter delivery. In other embodiments, the housing 30 can be prismatic or any other shape to facilitate the performance of the functions and utilities described herein. The housing 30 can include, for example, a delivery tool interface member 26 at the proximal end 34 for engaging a delivery tool during implantation of the device 10.

[0057] During cardiac therapy, for example, during sensing and / or pacing, all or a portion of the housing 30 can be used as an electrode. In the example shown, the housing-based electrode 24 is shown as circumscribing the proximal portion of the housing 30. When the housing 30 is formed of a conductive material (such as a titanium alloy or other examples listed above), various portions of the housing 30 are electrically insulated by a non-conductive material (such as a coating of parylene, polyurethane, silicone, epoxy resin, or other biocompatible polymer), leaving one or more discrete regions of the conductive material exposed to define the proximal housing-based electrode 24. When the housing 30 is formed of a non-conductive material (such as a ceramic, glass, or polymeric material), a conductive coating or layer (such as titanium, platinum, stainless steel, or an alloy thereof) can be applied to one or more discrete regions of the housing 30 to form the proximal housing-based electrode 24. In other examples, the proximal housing-based electrode 24 can be a component mounted or assembled on the housing 30, such as a ring electrode. The proximal housing-based electrode 24 can be electrically coupled to the internal circuitry of the device 10, for example, via the conductive housing 30 or via an electrical conductor when the housing 30 is a non-conductive material.

[0058] In the example shown, the proximal housing-based electrode 24 is positioned closer to the proximal end region 34 of the housing than the distal end region 32 and is thus referred to as the "proximal housing-based electrode" 24. However, in other examples, the housing-based electrode 24 can be positioned at other locations along the housing 30, for example, at a relatively more distal location than the location shown.

[0059] At the distal end region 32, the device 10 can include a distal fixation and electrode assembly 36, which can include one or more dart electrodes 12 of equal or unequal length in addition to including one or more fixation members 20. The dart electrode 12 can include a shaft 40 extending distally away from the distal end region 32 of the housing and can include one or more electrode elements, such as a tip electrode 42 at or near the free distal end region of the shaft 40. The tip electrode 42 can have a conical or hemispherical distal tip having a relatively narrow tip diameter (e.g., less than about 1 mm) for puncturing and passing through tissue layers without the use of a sharp tip or a needle-like tip having a sharp edge or beveled edge.

[0060] The shaft 40 of the dart electrode 12 can be a generally straight member and can be rigid. In other embodiments, the shaft 40 can be described as being relatively stiff but still having limited flexibility in the lateral direction. Further, the shaft 40 can be non-rigid to allow some lateral bending with the movement of the heart. However, in a relaxed state, when not subjected to any external forces, the shaft 40 can maintain the straight position as shown to keep the tip electrode 42 spaced apart from the distal end region 32 of the housing by at least the height 47 of the shaft 40. The dart electrode 12 can be configured to pierce through one or more tissue layers to position the tip electrode 42 within a desired tissue layer (e.g., ventricular myocardium). Thus, the height 47 of the shaft 40 can correspond to the depth of the desired pacing site, and the shaft can have a relatively high compressive strength along its longitudinal axis to resist bending in the lateral or radial directions when pressed against the implantation region 4. If a second dart electrode 12 is employed, its length can be unequal to the depth of the desired pacing site and can be configured to act as a neutral electrode for delivering pacing energy to the tissue. A longitudinal axial force can be applied to the tip electrode 42, e.g., by applying a longitudinal thrust to the proximal end 34 of the housing 30, to advance the dart electrode 12 into the tissue within the target implantation region. The shaft 40 can be longitudinally non-compressible. When subjected to lateral or radial forces, the shaft 40 can be elastically deformable in the lateral or radial directions to allow temporary bending (e.g., with tissue movement), but can return to its normal straight position when the lateral force disappears. When the shaft 40 is not exposed to any external forces or is only exposed to forces along its longitudinal central axis, the shaft 40 can maintain the straight linear position as shown.

[0061] One or more fixation members 20 can be described as having one or more “tines” with a generally curved position. These tines can be held in a distally extending position within the delivery tool. The distal tips of the tines can penetrate the heart tissue to a limited depth before elastically bending proximally back to the generally curved position (shown) after release from the delivery tool. Further, the fixation member 20 can include one or more aspects described, for example, in U.S. Patent No. 9,675,579 (Grubac et al.) issued on June 13, 2017, and U.S. Patent No. 9,119,959 (Rys et al.) issued on September 1, 2015, each of which is incorporated herein by reference in its entirety.

[0062] In some examples, the distal fixation and electrode assembly 36 includes a distal housing-based electrode 22. In the case of using the device 10 as a pacemaker for multi-chamber pacing (e.g., dual-chamber or triple-chamber pacing) and sensing, the tip electrode 42 can be used as the cathode electrode, which is paired with the proximal housing-based electrode 24 that serves as the return anode electrode. Alternatively, the distal housing-based electrode 22 can serve as the return anode electrode paired with the tip electrode 42 for sensing ventricular signals and delivering ventricular pacing pulses. In other examples, the distal housing-based electrode 22 can be the 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 serves as the atrial cathode electrode, the proximal housing-based electrode 24 can serve as the return anode paired with the tip electrode 42 for ventricular pacing and sensing, and can also serve as the return anode paired with the distal housing-based electrode 22 for atrial pacing and sensing.

[0063] As shown in this illustration, the target implantation region 4 in some pacing applications is along the atrial endocardium 18, typically below the AV node 15 and the His bundle 5. The dart electrode 42 can define a height 47 of the shaft 40 for penetrating through the atrial endocardium 18 in the target implantation region 4, through the central fibrous body 16 and into the ventricular myocardium 14 without penetrating through the ventricular endocardial surface 17. When the height 47 of the dart electrode 12 is fully advanced into the target implantation region 4, the tip electrode 42 can be located within the ventricular myocardium 14, and the distal housing-based electrode 22 can be positioned in close contact with or adjacent to the atrial endocardium 18. The dart electrode 12 can have a total combined height 47 of the tip electrode 42 and the shaft 40, which is about 3 mm to about 8 mm in various examples. The diameter of the shaft 40 can be less than about 2 mm, and can be about 1 mm or less, or even about 0.6 mm or less.

[0064] The device 10 can include a motion detector 11 within the housing 30. The 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 motion sensor 11 can be used to detect right atrial mechanical activity. Non-limiting examples of the motion detector 11 include accelerometers. In some embodiments, the mechanical activity detected by the motion detector 11 can be used to supplement or replace the electrical activity detected by one or more of the electrodes of the device 10. For example, the motion detector 11 can be used in addition to the proximal housing-based electrode 24, or the motion detector 11 can be used as an alternative to the proximal housing-based electrode 24.

[0065] The motion detector 11 may also be used for frequency response detection or for providing a frequency response IMD. Various techniques related to frequency response are described in U.S. Patent No. 5,154,170 (Bennett et al.) entitled "Optimization for rate responsive cardiac pacemaker" issued on October 13, 1992 and U.S. Patent No. 5,562,711 entitled "Method and apparatus for rate-responsive cardiac pacing" issued on October 8, 1996. Each of these U.S. patents is hereby incorporated by reference in its entirety.

[0066] Figure 3 is a three-dimensional perspective view of the device 10 capable of cardiac therapy. As shown, the distal fixation and electrode assembly 36 includes a distal housing-based electrode 22 implemented as a toroidal electrode. When the fixation member tines 20a, 20b, and 20c of the fixation member 20 engage atrial tissue, the distal housing-based electrode 22 can be positioned in close contact with or operably adjacent to the atrial tissue. The elastically deformable tines 20a, 20b, and 20c can extend distally during delivery of the device 10 to the implantation site. For example, the tines 20a, 20b, and 20c can puncture the atrial endocardial surface when the device 10 is pushed out of the delivery tool and bends back to its normal bent position (as shown) when no longer constrained within the delivery tool. When the tines 20a, 20b, and 20c bend back to their normal positions, the fixation member 20 can pull the distal fixation and electrode assembly 36 toward the atrial endocardial surface. When the distal fixation and electrode assembly 36 is pulled toward the atrial endocardium, the tip electrode 42 can be advanced through the atrial myocardium and the central fibrous body and into the ventricular myocardium. The distal housing-based electrode 22 can then be positioned against the atrial endocardial surface.

[0067] The distal housing-based electrode 22 may include a ring formed of a conductive material such as titanium, platinum, iridium, or an alloy thereof. The distal housing-based electrode 22 may be a single continuous annular electrode. In other examples, portions of the ring may be coated with an electrically insulating coating such as parylene, polyurethane, silicone, epoxy resin, or other insulating coatings to reduce the conductive surface area of the annular electrode. For example, one or more sectors of the ring 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 (e.g., by covering portions of the conductive ring with an insulating coating) may increase the impedance of the distal housing 22 and thereby reduce the current delivered during a pacing pulse that captures myocardial tissue (e.g., atrial myocardial tissue). Lower current consumption may conserve the power source of the device 10, e.g., one or more rechargeable or non-rechargeable batteries.

[0068] As described above, the distal housing-based electrode 22 may be configured as a ventricular cathode electrode for use in combination with the proximal housing-based electrode 24 as a return anode to deliver a pacing pulse to atrial tissue at the implant site. Electrodes 22 and 24 may be used to sense atrial P waves for use in controlling atrial pacing pulses (delivered in the absence of a sensed P wave), and for controlling atrial synchronous ventricular pacing pulses that are delivered using the tip electrode 42 as a cathode and the proximal housing-based electrode 24 as a return anode. In other examples, the distal housing-based electrode 22 may be used as a return anode in combination with the cathode tip electrode 42 for ventricular pacing and sensing.

[0069] Figure 4 is a block diagram of a circuit system that may be enclosed within a housing 30 ( Figure 3 ) to use the device 10 to provide cardiac therapy functions. A separate medical device 50 ( Figure 1 ) may include some or all of the same components, which may be configured in a similar manner. The electronic circuit system enclosed within the housing 30 may include software, firmware, and hardware that cooperate to monitor atrial and ventricular electrocardiographic signals, determine when cardiac therapy is required, and / or deliver electrical pulses to the patient's heart according to programmed pacing modes and pulse control parameters. The electronic circuit system may include a control circuit 80 (e.g., including processing circuitry), a memory 82, a therapy delivery circuit 84, a sensing circuit 86, and / or a telemetry circuit 88. In some examples, the device 10 includes one or more sensors 90 for generating signals related to the patient's physiological function, state, or condition, such as a patient activity sensor, for use in determining the need for pacing therapy and / or controlling the pacing rate.

[0070] Power source 98 can supply power to the circuitry of device 10 (including each of components 80, 82, 84, 86, 88, and 90) as needed. The power source 98 can include one or more energy storage devices, such as one or more rechargeable or non-rechargeable batteries. The connections between the power source 98 and each of components 80, 82, 84, 86, and 88 will be understood from the overall block diagram but are not shown for clarity. For example, the power source 98 can be coupled to one or more charging circuits included in the therapy delivery circuit 84 to supply the required power to a charge-holding capacitor included in the therapy delivery circuit 84, which discharges at an appropriate time under the control of the control circuit 80 to deliver a pacing pulse, for example, according to a dual-chamber pacing mode such as DDI(R). The power source 98 can also be coupled to components of the sensing circuit 86 (such as a sensing amplifier, an analog-to-digital converter, switching circuitry, etc.), the sensor 90, the telemetry circuit 88, and the memory 82 to supply power to the various circuits.

[0071] Any suitable technique can be used to recharge the rechargeable power source 98. In some embodiments, the device 10 can include an antenna, an inductive coil, or other inductive coupling structures configured to couple to another device (such as an external charger or programmer) for in-situ power reception. Various examples of charging leadless implantable medical devices are described in U.S. Patent Publication No. 2018 / 0212451 (Schmidt et al.) titled “Recharge of Implanted Medical Devices,” filed on Jan. 26, 2017, which is incorporated herein by reference in its entirety. The device 10 can also be configured to extend the life of the power source 98 using various techniques (such as a low-power mode).

[0072] Various examples of power sources and various techniques related to power sources can be used, such as those found in, for example, U.S. Patent No. 8,383,269 (Scott et al.), issued on Feb. 26, 2013, U.S. Patent No. 8,105,714 (Schmidt et al.), issued on Jan. 31, 2012, and U.S. Patent No. 7,635,541 (Scott et al.), issued on Dec. 22, 2009, which are incorporated herein by reference in their entireties.

[0073] The functional blocks shown represent the functions included in device 10 and may include any discrete and / or integrated electronic circuit components implementing analog and / or digital circuitry capable of performing the functions attributable to the medical device 10 herein. The various components may include processing circuitry such as application specific integrated circuits (ASICs), electronic circuits, processors (shared, dedicated, or grouped) executing one or more software or firmware programs and memories, combinational logic circuits, state machines, or other suitable components or combinations of components providing the described functionality. The specific form of software, hardware, and / or firmware employed to implement the functions disclosed herein will be primarily determined by the particular system architecture employed in the medical device and by the particular detection and treatment delivery methods employed by the medical device. Given the disclosure herein, it is within the ability of those skilled in the art to provide software, hardware, and / or firmware for performing the described functions in the context of any modern cardiac medical device system.

[0074] Memory 82 may include any volatile, non-volatile, magnetic, or electrical 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. Additionally, 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 circuitry to perform single-chamber, dual-chamber, or triple-chamber pacing (e.g., single-chamber or multi-chamber pacing) functions or other sensing and treatment delivery functions attributable to device 10. The non-transitory computer-readable medium storing the instructions may include any of the media listed above.

[0075] Control circuit 80 may communicate, for example via a data bus, with treatment delivery circuit 84 and sensing circuit 86 for sensing cardiac electrical signals and controlling the delivery of cardiac electrical stimulation therapy in response to sensed cardiac events (e.g., P waves and R waves, or absence of P waves or R waves). Tip electrode 42, distal housing-based electrode 22, and proximal housing-based electrode 24 may be electrically coupled to treatment delivery circuit 84 for delivering electrical stimulation pulses to a patient's heart and are electrically coupled to sensing circuit 86 and for sensing cardiac electrical signals.

[0076] The sensing circuit 86 may include an atrial (A) sensing channel 87 and a ventricular (V) sensing channel 89. The distal housing-based electrode 22 and the proximal housing-based electrode 24 may be coupled to the atrial sensing channel 87 for sensing atrial signals, e.g., the P wave associated with atrial myocardial depolarization. In examples including two or more selectable distal housing-based electrodes, the sensing circuit 86 may include switching circuitry for selectively coupling one or more of the available distal housing-based electrodes to the cardiac event detection circuitry included in the atrial sensing channel 87. The switching circuitry may include a switch array, a switch matrix, a multiplexer, or any other type of switching device suitable for selectively coupling components of the sensing circuit 86 to selected electrodes. The tip electrode 42 and the proximal housing-based electrode 24 may be coupled to the ventricular sensing channel 89 for sensing ventricular signals, e.g., the R wave associated with ventricular myocardial depolarization.

[0077] Each of the atrial sensing channel 87 and the ventricular sensing channel 89 may include cardiac event detection circuitry for detecting the P wave and the R wave, respectively, from the cardiac electrical signals received by the respective sensing channels. The cardiac event detection circuitry included in each of channels 87 and 89 may be configured to amplify, filter, digitize, and rectify the cardiac electrical signals received from the selected electrodes to improve the signal quality for detecting cardiac electrical events. The cardiac event detection circuitry within each of channels 87 and 89 may include one or more sense amplifiers, filters, rectifiers, threshold detectors, comparators, analog-to-digital converters (ADCs), timers, or other analog or digital components. The cardiac event sensing thresholds, e.g., the P wave sensing threshold and the R wave sensing threshold, may be automatically adjusted by each respective sensing channel 87 and 89 under the control of the control circuit 80, e.g., based on timing periods and sensing thresholds determined by the control circuit 80, stored in the memory 82, and / or controlled by the hardware, firmware, and / or software of the control circuit 80 and / or the sensing circuit 86.

[0078] When a cardiac electrical event is detected based on a sensed threshold crossing, the sensing circuit 86 can generate a sensed event signal that is transmitted to the control circuit 80. For example, an atrial sensing channel 87 can generate a P-wave sensed event signal in response to a P-wave sensed threshold crossing. A ventricular sensing channel 89 can generate an R-wave sensed event signal in response to an R-wave sensed threshold crossing. The sensed event signal can be used by the control circuit 80 to set a pacing escape interval timer that controls the base time interval for scheduling cardiac pacing pulses. The sensed event signal can trigger or inhibit a pacing pulse depending on the particular programmed pacing mode. For example, a P-wave sensed event signal received from the atrial sensing channel 87 can cause the control circuit 80 to inhibit a scheduled atrial pacing pulse and schedule a ventricular pacing pulse at a programmed atrioventricular (AV) pacing interval. If an R-wave is sensed before the expiration of the AV pacing interval, the ventricular pacing pulse can be inhibited. If the AV pacing interval expires before the control circuit 80 receives an R-wave sensed event signal from the ventricular pacing channel 89, the control circuit 80 can use the therapy delivery circuit 84 to deliver a scheduled ventricular pacing pulse synchronized to the sensed P-wave.

[0079] In some examples, the device 10 can be configured to deliver various pacing therapies, including bradycardia pacing, cardiac resynchronization therapy, post-shock pacing, and / or tachycardia-related therapies such as ATP, and the like. For example, the device 10 can be configured to detect non-sinus tachycardia and deliver ATP. The control circuit 80 can determine cardiac event time intervals, such as the PP interval between consecutive P-wave sensed event signals received from the atrial sensing channel 87, the RR interval between consecutive R-wave sensed event signals received from the ventricular sensing channel 89, and the P-R and / or R-P intervals received between a P-wave sensed event signal and an R-wave sensed event signal. These intervals can be compared to tachycardia detection intervals for detecting non-sinus tachycardia. Tachycardia can be detected in a given cardiac chamber based on a threshold number of tachycardia detection intervals being detected.

[0080] The therapy delivery circuit 84 can include an atrial pacing circuit 83 and a ventricular pacing circuit 85. Each of the pacing circuits 83 and 85 can include charging circuitry, one or more charge storage devices (such as one or more low-voltage hold capacitors), an output capacitor, and / or switch circuitry that controls when the (multiple) hold capacitors are charged and when to discharge across the output capacitor to deliver a pacing pulse to a pacing electrode vector coupled to the respective pacing circuit 83 or 85. The tip electrode 42 and the proximal housing-based electrode 24 can be coupled to the ventricular pacing circuit 85 as a bipolar cathode and anode pair for delivering a ventricular pacing pulse, for example, at the expiration of an AV or VV pacing interval set by the control circuit 80, for providing atrial-synchronized ventricular pacing and a baseline lower ventricular pacing rate.

[0081] The atrial pacing circuit 83 can be coupled to the distal housing-based electrode 22 and the proximal housing-based electrode 24 for delivering atrial pacing pulses. The control circuit 80 can set the atrial pacing interval according to a programmed lower pacing rate or a temporary lower rate set according to the pacing rate indicated by a rate-responsive sensor. If the atrial pacing interval expires before a P-wave sensing event signal is received from the atrial sensing channel 87, the atrial pacing circuit can be controlled to deliver an atrial pacing pulse. In response to the delivered atrial pacing pulse, the control circuit 80 starts an AV pacing interval to provide synchronized multi-chamber pacing (e.g., dual-chamber or triple-chamber pacing).

[0082] The hold capacitors of the atrial or ventricular pacing circuits 83 or 85 can be charged to a programmed pacing voltage amplitude and discharged for a programmed pacing pulse width by the therapy delivery circuit 84 in accordance with control signals received from the control circuit 80. For example, the pacing timing circuit included in the control circuit 80 can include a programmable digital counter set by the microprocessor of the control circuit 80 for controlling the base pacing time intervals associated with various single-chamber or multi-chamber pacing (e.g., dual-chamber or triple-chamber pacing) modes or anti-tachycardia pacing sequences. The microprocessor of the control circuit 80 can also set the amplitude, pulse width, polarity, or other characteristics of the cardiac pacing pulses, and these parameters can be based on programmed values stored in the memory 82.

[0083] The device 10 can include other sensors 90 for sensing signals from the patient, which are used in determining the need for and / or controlling the electrical stimulation therapy delivered by the therapy delivery circuit 84. In some examples, sensors indicating a need for increased cardiac output can include patient activity sensors such as accelerometers. The control circuit 80 can determine an increase in the patient's metabolic demand due to increased activity as indicated by the patient activity sensor for use in determining the pacing rate indicated by the sensor.

[0084] The control parameters used by the control circuit 80 for sensing cardiac events and controlling pacing therapy delivery can be programmed into the memory 82 via the telemetry circuit 88, which can also be described as a communication interface. The telemetry circuit 88 includes a transceiver and an antenna for communicating with an external device (such as a programmer or a home monitor) using radio frequency communication or other communication protocols. The control circuit 80 can use the telemetry circuit 88 to receive downlink telemetry from an external device and send uplink telemetry to the external device. In some cases, the telemetry circuit 88 can be used to transmit communication signals to and receive communication signals from another medical device implanted in the patient.

[0085] Figure 5Is a three-dimensional perspective view of another leadless endocardial medical device 710 that can be configured for single-chamber or multi-chamber cardiac therapy (e.g., dual-chamber or triple-chamber cardiac therapy) according to another example. Device 710 may include a housing 730 having an outer sidewall 735, shown as a cylindrical outer sidewall, that extends from a housing distal end region 732 to a housing proximal end region 734. Housing 730 may enclose electronic circuitry configured to perform single-chamber or multi-chamber cardiac therapy, including atrial and ventricular cardiac electrical signal sensing and pacing of atrial and ventricular chambers. A delivery tool interface member 726 is shown on housing proximal end region 734.

[0086] A distal fixation and electrode assembly 736 may be coupled to housing distal end region 732. Distal fixation and electrode assembly 736 may include an electrically insulating distal member 772 coupled to housing distal end region 732. A tissue piercing electrode 712 extending away from housing distal end region 732 and a plurality of non-tissue piercing electrodes 722 may be directly coupled to insulating distal member 772. Tissue piercing electrode 712 extends away from housing distal end region 732 in a longitudinal direction and may be coaxial with the longitudinal central axis 731 of housing 730.

[0087] Tissue piercing distal electrode 712 may include an electrically insulating shaft 740 and a tip electrode 742. In some examples, tissue piercing distal electrode 712 is an active fixation member that includes a helical shaft 740 and a distal cathode tip electrode 742. Helical shaft 740 may extend from a shaft distal end region 743 to a shaft proximal end region 741, which may be directly coupled to insulating distal member 772. Helical shaft 740 may be coated with an electrically insulating material (e.g., parylene or other examples listed herein) to avoid cardiac tissue sensing or stimulation along the shaft length. Tip electrode 742 is at shaft distal end region 743 and may act as a cathode electrode for delivering ventricular pacing pulses and sensing ventricular electrical signals using a proximal housing-based electrode 724 as a return anode when tip electrode 742 is advanced into ventricular tissue. Proximal housing-based electrode 724 may be an annular electrode around housing 730 and may be defined by a non-insulating portion of longitudinal sidewall 735. Other portions of housing 730 that do not act as electrodes may be coated with an electrically insulating material as described above in connection with Figure 2 as described.

[0088] Two or more tissue piercing electrodes (e.g., any type) punctured into the LV myocardium can be used for more local pacing capture and can mitigate ventricular pacing spikes that affect captured atrial tissue. In some embodiments, the plurality of tissue piercing electrodes may include dart-type electrodes (e.g., Figures 1 - 2two or more of the electrode 12) and the helical electrode (e.g., electrode 712) in []. Non-limiting examples of multiple tissue piercing electrodes include two dart electrodes, a helical electrode with a dart electrode extending therefrom (e.g., through the center), or a double intertwined helix. Multiple tissue piercing electrodes can also be used for bipolar or multipolar pacing.

[0089] In some embodiments, one or more tissue piercing electrodes (e.g., any type of tissue piercing electrode) piercing into the LV myocardium can be multipolar tissue piercing electrodes. The multipolar tissue piercing electrodes can include one or more electrically active or electrically isolated elements, which can enable bipolar or multipolar pacing from one or more tissue piercing electrodes.

[0090] A plurality of non-tissue piercing electrodes 722 can be provided along the outer periphery of the insulating distal member 772, outside the tissue piercing electrode 712. The insulating distal member 772 can define a distally facing surface 738 and a circumferential surface 739 of the device 710, and the circumferential surface 739 surrounds the device 710 and is adjacent to the longitudinal sidewall 735 of the housing. The non-tissue piercing electrodes 722 can be formed of a conductive material (such as titanium, platinum, iridium, or an alloy thereof). In the illustrated embodiment, six non-tissue piercing electrodes 722 are radially spaced apart at equal distances along the outer periphery of the insulating distal member 772. However, two or more non-tissue piercing electrodes 722 can be provided.

[0091] The non-tissue piercing electrodes 722 can be discrete components, each held within a corresponding groove 774 in the insulating member 772, and the corresponding groove 774 is sized and shaped to mate with the non-tissue piercing electrode 722. In other examples, the non-tissue piercing electrodes 722 can each be a non-insulated exposed portion of an integral member mounted within or on the insulating distal member. The intermediate portion of the integral member that is not used as an electrode can be insulated by the insulating distal member 772, or if exposed to the surrounding environment, can be coated with an electrical insulating coating (such as parylene, polyurethane, silicone, epoxy resin, or other insulating coatings).

[0092] When the tissue piercing electrode 712 is advanced into the heart tissue, at least one non-tissue piercing electrode 722 can be positioned against the heart tissue surface, positioned in close contact with the heart tissue surface, or positioned operatively adjacent to the heart tissue surface for delivering pulses and / or sensing cardiac electrical signals generated by the patient's heart. For example, when the tissue piercing electrode 712 is advanced into atrial tissue and through the central fibrous body until the distal tip electrode 742 is positioned in direct contact with ventricular tissue (e.g., ventricular myocardium and / or a part of the ventricular conduction system), the non-tissue piercing electrode 722 can be positioned in contact with the right atrial endocardial tissue for pacing and sensing in the atrium.

[0093] The non-tissue penetrating electrode 722 can be coupled to a treatment delivery circuit 84 and a sensing circuit 86 (see Figure 4 ) enclosed by a housing 730 for jointly serving as a cathode electrode for delivering atrial pacing pulses and sensing atrial electrical signals, such as P waves, in combination with a proximal housing-based electrode 724 as a return anode. The switching circuitry included in the sensing circuit 86 can be activated under the control of a control circuit 80 to couple one or more of the non-tissue penetrating electrodes to an atrial sensing channel 87. The distal non-tissue penetrating electrodes 722 can be electrically isolated from each other such that each individual electrode among the electrodes 722 can be individually selected by the switching circuitry included in the treatment delivery circuit 84 to individually serve as or serve as an atrial cathode electrode in combination with two or more of the electrodes 722. The switching circuitry included in the treatment delivery circuit 84 can be activated under the control of the control circuit 80 to couple one or more of the non-tissue penetrating electrodes 722 to an atrial pacing circuit 83. Two or more of the non-tissue penetrating electrodes 722 can be selected at a time to operate as a multipoint atrial cathode electrode.

[0094] Certain non-tissue penetrating electrodes 722 selected for atrial pacing and / or atrial sensing can be selected based on atrial capture threshold detection, electrode impedance, P wave signal strength in cardiac electrical signals, or other factors. For example, a single electrode or any combination of electrodes that provides an optimal combination of a low pacing capture threshold amplitude and a relatively high electrode impedance among two or more individual non-tissue penetrating electrodes 722 that serve as cathode electrodes can be selected to achieve reliable atrial pacing with minimal current consumption from a power source 98.

[0095] In some instances, when the tissue penetrating electrode 712 anchors the housing 730 at the implantation site, the distally facing surface 738 can uniformly contact the atrial endocardial surface. In this case, all of the electrodes 722 can be selected together for forming an atrial cathode. Alternatively, every other electrode among the electrodes 722 can be selected together for forming a multipoint atrial cathode having a relatively high impedance that is still uniformly distributed along the distally facing surface 738. Alternatively, a subset of one or more electrodes 722 along one side of the insulating distal member 772 can be selected to provide pacing at a desired site, which achieves a lowest pacing capture threshold due to the relative position of the electrode 722 with respect to the atrial tissue being paced.

[0096] In other instances, depending on the location and orientation of the tissue-puncturing electrode 712 within the cardiac tissue, the distally-facing surface 738 may be oriented at an angle relative to the adjacent endocardial surface. In such a case, one or more of the non-tissue-puncturing electrodes 722 may be positioned to be in closer contact with the adjacent endocardial tissue than other non-tissue-puncturing electrodes 722, which may be angled with respect to the endocardial surface. By providing a plurality of non-tissue-puncturing electrodes along the outer periphery of the insulating distal member 772, the angle of the tissue-puncturing electrode 712 and the distal end region 732 of the housing relative to the cardiac surface (e.g., the right atrial endocardial surface) may be required to be substantially parallel. Anatomical and positional variations may cause the distally-facing surface 738 to be angled or tilted with respect to the endocardial surface; however, the plurality of non-tissue-puncturing electrodes 722 distributed along the outer periphery of the insulating distal member 772 increases the likelihood of good contact between one or more of the electrodes 722 and the adjacent cardiac tissue to facilitate an acceptable pacing threshold and reliable sensing of cardiac events using at least a subset of the plurality of electrodes 722. Circumferential contact or fixation along the entire outer periphery of the insulating distal member 772 may not be required.

[0097] The non-tissue-puncturing electrodes 722 are shown as each including a first portion 722a extending along the distally-facing surface 738 and a second portion 722b extending along the circumferential surface 739. The first portion 722a and the second portion 722b may be continuous exposed surfaces such that the effective electrode surface wraps around the outer peripheral edge 776 of the insulating distal member 772, which engages the distally-facing surface 738 and the circumferential surface 739. The non-tissue-puncturing electrodes 722 may include one or more of the electrodes 772 along the distally-facing surface 738, one or more electrodes along the circumferential surface 739, one or more electrodes each extending along both the distally-facing surface 738 and the circumferential surface 739, or any combination thereof. The exposed surface of each of the non-tissue-puncturing electrodes 722 may be flush with the corresponding distally-facing surface 738 and / or circumferential surface. In other examples, each of the non-tissue-puncturing electrodes 722 may have a raised surface projecting from the insulating distal member 772. However, any raised surface of the electrode 722 may define a smooth or rounded non-tissue-puncturing surface.

[0098] The distal fixation and electrode assembly 736 can seal the distal end region of the housing 730 and can provide a base on which the electrodes 722 are mounted. The electrodes 722 can be referred to as housing-based electrodes. These electrodes 722 may not be carried by a shaft or other extension that extends the active electrode portion away from the housing 730, similar to the distal tip electrode 742 that resides at the distal tip of the helical shaft 740 that extends away from the housing 730. Other examples of non-tissue-puncturing electrodes coupled to the distal-facing surface and / or circumferential surface of the insulating distal member presented herein include distal housing-based annular electrodes 22( Figure 3 ), distal housing-based annular electrodes that extend circumferentially around the assembly 36( Figure 3 ), button electrodes, other housing-based electrodes, and other circumferential annular electrodes. Any non-tissue-puncturing electrode directly coupled to the distal insulating member and located peripherally to the central tissue-puncturing electrode can be provided to be used individually as a cathode electrode, together as a cathode electrode, or in any combination as a cathode electrode for delivering pacing pulses to adjacent cardiac tissue. When annular electrodes (such as the distal annular electrode 22 and / or the circumferential annular electrode) are provided, multiple portions of the annular electrode can be electrically insulated by a coating to provide multiple distributed non-tissue-puncturing electrodes along the distal-facing surface and / or circumferential surface of the insulating distal member.

[0099] Compared with the tissue-puncturing electrodes provided along the distal fixation and electrode assembly 736, the non-tissue-puncturing electrodes 722 and the other examples listed above are expected to provide more reliable and effective atrial pacing and sensing. Compared with the ventricular chamber wall, the atrial chamber wall is relatively thin. The tissue-puncturing atrial cathode electrode can extend too deeply into the atrial tissue, resulting in accidental continuous or intermittent capture of the ventricular tissue. Since the ventricular signal has a greater signal intensity in the cardiac electrical signals received by the tissue-puncturing atrial cathode electrode that is physically closer to the ventricular tissue, the tissue-puncturing atrial cathode electrode can cause interference with the sensing of atrial signals. The tissue-puncturing electrode 712 can be safely anchored into the ventricular tissue to stabilize the implantation position of the device 710 and provide reasonable certainty that the tip electrode 742 is sensing and pacing in the ventricular tissue, while the non-tissue-puncturing electrode 722 is reliably pacing and sensing in the atrium. When the device 710 is implanted in the target implantation region 4 (e.g., as Figure 1When in the ventricular septum shown, the tip electrode 742 can reach the left ventricular tissue for pacing the left ventricle, rather than the tissue piercing electrode 722 providing pacing and sensing in the right atrium. The length of the tissue piercing electrode 712 from the distally facing surface 738 can range from about 4 mm to about 8 mm to reach the left ventricular tissue. In some instances, the device 710 can achieve four-chamber pacing by: delivering atrial pacing pulses from the atrial pacing circuit 83 via the non-tissue piercing electrode 722 in the target implantation region 4 to achieve biatrial (right atrium and left atrium) capture, and delivering ventricular pacing pulses from the ventricular pacing circuit 85 via the tip electrode 742 advanced from the target implantation region 4 into the ventricular tissue to achieve biventricular (right ventricle and left ventricle) capture.

[0100] Figures 6 - 14 Relates to various methods of tissue piercing electrodes that can be used to position any of the devices described herein (e.g., those shown in Figures 1 - 5 and Figures 16 - 18 ). Specifically, each of these methods can be used when positioning or implanting a tissue piercing electrode from the Koch triangle region of the right atrium through the right atrial endocardium and the central fibrous body into the basal region and / or septal region of the left ventricular myocardium of a patient's heart.

[0101] Figure 6 Is a flowchart of a cardiac treatment method 100 for use with a system 2 such as Figure 1 . For example, the method 100 can be used with an intracardiac medical device 10 ( Figures 1 - 2 ) or 710 ( Figure 5 ). The method 100 can be used to describe single-chamber or multi-chamber pacing (e.g., dual-chamber or triple-chamber pacing), atrioventricular synchronous pacing, triggered pacing, cardiac resynchronization pacing, or tachycardia-related treatment.

[0102] The method 100 can include a process 102 in which the activity of the right atrium is monitored. The medical device can use one or more of a plurality of electrodes to monitor the electrical activity of a patient's heart. For example, after implantation, a right atrial electrode (e.g., Figure 2 's proximally housing-based electrode 24 or distally housing-based electrode 22) can be positioned for sensing the electrical activity of the right atrium. In some embodiments, the right atrial electrode can be positioned within the volume of the right atrium or positioned against the right atrial endocardial surface of the patient's heart. In some embodiments, the right atrial electrode can be used to deliver cardiac treatment to the right atrium of the patient's heart. The right atrial electrode can be coupled to the housing of the medical device without a lead. For example, the right atrial electrode can be positioned at the distal end region of the housing or at a position proximal to the distal end region (e.g., the proximal end region of the housing).

[0103] In addition to, or in lieu of, using a right atrial electrode, a medical device may use a motion sensor to monitor the mechanical activity of a patient's heart. For example, after implantation, a right atrial motion detector may be positioned to sense the mechanical activity of the right atrium. In some embodiments, the right atrial motion detector may be positioned within the implantable medical device 10. In some embodiments, the right atrial motion detector may be wirelessly coupled or coupled using leads to the implantable medical device 10. The motion detector may be coupled to the same or a different sensing circuit as the electrode.

[0104] Method 100 may further include process 104 in which pacing therapy is delivered to the ventricles. For example, in process 104, in response to the activity of the right atrium monitored in process 102, pacing therapy may be delivered to the left ventricle, right ventricle, ventricular septum (e.g., the upper posterior basal septal region), or other portions of the ventricular myocardium. The monitored activity may include electrical activity, mechanical activity, or both electrical and mechanical activity (e.g., using a right atrial electrode and / or a right atrial motion detector). The medical device may use one or more of the plurality of electrodes to deliver cardiac therapy to the patient's heart. For example, after implantation, a tissue piercing electrode (e.g., tip electrode 42) may be positioned in the ventricular septum for delivering cardiac therapy to the left ventricle of the patient's heart. The tissue piercing electrode may be wirelessly coupled to the housing. In some embodiments, the tissue piercing electrode may be used to sense the electrical activity of the left ventricle. The tissue piercing electrode may extend from the distal end region of the housing.

[0105] As mentioned above, method 100 can be used in conjunction with cardiac resynchronization pacing (e.g., cardiac resynchronization therapy). In some embodiments of using cardiac resynchronization pacing, pacing can be delivered to one or both ventricles in response to a sensed atrial or ventricular event. Examples of cardiac resynchronization pacing include biventricular pacing and single-ventricular pacing. Single-ventricular pacing can include left ventricular pacing, right ventricular pacing, or fusion pacing. Various methods of performing cardiac resynchronization pacing are described in U.S. Patent Application Publication No. 2017 / 0340885 (Sambelashvili) titled "Systems and methods for leadless cardiac resynchronization therapy" filed on Jul. 31, 2017, and U.S. Patent No. 9,789,319 (Sambelashvili) titled "Systems and methods for leadless cardiac resynchronization therapy" issued on Oct. 17, 2017, each of which is incorporated herein by reference in its entirety.

[0106] One type of cardiac resynchronization pacing is biventricular pacing. Biventricular pacing can include pacing the right ventricle (RV) using an RV electrode and pacing the left ventricle (LV) using an LV electrode (e.g., a tissue piercing electrode), where the RV electrode and the LV electrode are typically different electrodes. In one or more embodiments, the implantable medical device can be configured to automatically switch between biventricular pacing and fusion pacing. Generally, the main goal can be to ensure that the ventricles are synchronized with each other. Single-ventricular pacing or especially fusion pacing can be used to replace biventricular pacing to achieve synchronization. Those skilled in the art understand that adaptive CRT can be used to treat a patient's heart, in which biventricular pacing can be delivered during a period of time (e.g., 1 hour, 1 day, 1 week, etc.), and at another time, fusion pacing can be delivered to resynchronize the ventricles. Generally, fusion pacing involves pacing the LV. However, there can be cases where only the RV is paced.

[0107] One type of adaptive CRT is adaptive LV pacing. Adaptive LV pacing can be described as pre-pacing the LV to synchronize with the native RV activation, thereby utilizing the native RV conduction. The timing of LV pacing can be automatically adjusted based on the atrial-to-native QRS interval measurement (AV interval). One or more embodiments can set the LV pacing to occur at approximately 70% of the native AV interval, but at least 40 ms before the native QRS.

[0108] One or more other embodiments may configure LV pacing in response to or based on a moderately prolonged QRS. For example, if the QRS width exceeds 120 ms but does not exceed 160 ms, LV pacing with fusion is selected. Otherwise, if the QRS width is greater than 160 ms, biventricular (BiV) pacing is selected. Implementing a moderately prolonged QRS threshold may be beneficial for heart failure patients. The efficacy of LV-only pacing or biventricular pacing may be predicted by a moderately prolonged QRS duration. An illustrative moderately prolonged QRS may correspond to a QRS width in the range of 130 ms - 150 ms.

[0109] Adaptive CRT may use intrinsic AV conduction to determine whether to use biventricular pacing or fusion pacing. In one or more embodiments, intrinsic AV conduction may be automatically evaluated. In one or more embodiments, an IMD (e.g., an ICD), a leadless pacing device (IPD) (e.g., an intravascular medical device), and / or a subcutaneous implantable device (SD) may automatically evaluate intrinsic ventricular conduction based on the QRS duration from a far-field electrogram (EGM), or the right ventricle sensed to left ventricle sensed (RVs-LVs) interval from an IMD sensing marker may be automatically evaluated by the IMD or SD. For further details, U.S. Patent No. 4,374,382 to Markowitz et al. describes IMD sensing markers, which is incorporated herein by reference in its entirety. Based on these results, fusion pacing (i.e., LV-only pacing or RV-only pacing) or biventricular pacing may be selected. For example, an RVs-LVs interval of no more than 150 ms may correspond to LV-only pacing, while an RVs-LVs interval > 150 ms may switch the algorithm to biventricular pacing. In one or more other embodiments, an RVs-LVs interval of no more than 80 ms corresponds to fusion pacing, while an RVs-LVs interval greater than 80 ms switches to biventricular pacing. Generally, the RVs-LVs is shorter than the corresponding QRS width. Thus, it takes approximately 40 ms to sense the onset of the QRS in the RV and also sense the final portion of the QRS in the LV before the end of the QRS.

[0110] Various devices may be used to perform the functions of adaptive CRT. In one or more other embodiments, the IMD may track moderately prolonged QRS over time and subsequently rely on trend data to switch between biventricular pacing and fusion pacing. For example, assume that the moderately prolonged QRS for six consecutive weeks is 120 ms, 125 ms, 130 ms, 135 m, 140 ms, and 145 ms, respectively. An increasing trend may trigger a switch to biventricular pacing before the threshold for switching to biventricular pacing is met.

[0111] In another embodiment, the SD may send a control signal to the LPD to initiate CRT. The LPD may sense cardiac signals (i.e., second electrical signals) from the patient's heart. Based on the cardiac signals, the LPD may determine whether to deliver CRT from the LPD to the heart. For example, based on the second electrical signals, the LPD may determine that CRT is not necessary. The LPD may consider whether the sensed data meets a pre-specified threshold. For example, if the QRS width does not exceed 120 ms, the LPD may inhibit delivery of CRT therapy (e.g., the LPD may then send a signal to the SD indicating that CRT should not be delivered based on the cardiac signals). The SD may be configured to perform a more detailed analysis where at least one or more parameters (such as at least two parameters) are evaluated. The SD may then send another command signal that confirms, overrides, or vetoes the LPD.

[0112] In another embodiment, the LPD may sense a cardiac signal that indicates that a switch between fused pacing and biventricular pacing should occur, and the LPD will send a signal to the SD. The SD may be configured to send an override signal to the LPD unless certain conditions are met.

[0113] In yet another embodiment, the LPD may determine that, contrary to communication with the SD, biventricular pacing may be used instead of fused pacing. In one embodiment, the LPD will deliver biventricular pacing. In one or more other embodiments, the LPD may determine that, contrary to communication with the SD, fused pacing may be used instead of biventricular pacing. In this scenario, the LPD may deliver fused pacing.

[0114] In another embodiment, the SD transmits a control signal to the LPD to initiate CRT. The LPD senses cardiac signals (i.e., second electrical signals) from the patient's heart. Based on the cardiac signals, the LPD may determine whether to deliver CRT or determine the type of CRT to be delivered from the LPD to the heart. In one or more embodiments, based on the second electrical signals, the LPD may initially determine that CRT should not be used. The initial determination made by the LPD may use tests such as thresholds for one or more parameters. In one or more embodiments, the SD may perform a more detailed analysis regarding whether CRT should be delivered. Using sensed data from the LPD and / or the SD, the SD may generate another signal to the LPD that confirms, overrides, or vetoes the LPD's initial determination.

[0115] In another embodiment, the LPD may sense a cardiac signal that indicates that a switch between fused pacing and biventricular pacing should occur. Whether to switch between fused pacing and biventricular pacing may be determined based on one or more parameters (e.g., moderately prolonged QRS, etc.). The LPD may be configured to automatically switch between fused pacing and biventricular pacing, or wait until the SD confirms or vetoes the switch between CRT pacing modes (i.e., fused pacing and biventricular pacing). The SD may be configured to send a confirmation signal, or a signal vetoing the LPD's switch of pacing mode.

[0116] In yet another embodiment, the LPD may determine that, contrary to communicating with the SD, biventricular pacing may be used instead of fused pacing. In one embodiment, the LPD will deliver biventricular pacing. In one or more other embodiments, the LPD may determine that, contrary to communicating with the SD, fused pacing is more needed compared to biventricular pacing. In this scenario, the LPD may deliver fused pacing.

[0117] In one or more other embodiments, a device having similar SD functionality is implanted in a patient's heart. For example, the SD may function as a conventional ICD or have the SD functionality described herein. Subsequently, an electrical signal is sensed from the patient's heart, the electrical signal including moderately prolonged QRS duration data. Based on the moderately prolonged QRS duration in the sensed electrical signal, a determination is made as to whether cardiac resynchronization pacing therapy (CRT pacing) is appropriate. CRT pacing pulses are delivered to the heart using electrodes. In one or more embodiments, the SD may switch between fused pacing and biventricular pacing based on data sensed from the heart (e.g., moderately prolonged QRS, etc.).

[0118] In addition, there are further embodiments that may be implemented using the methods described herein. One or more LPDs carrying one or more electrodes may be implanted in various chambers of a patient's heart, or otherwise in close proximity to the heart muscle. At these locations, the LPD may sense ECG signals with a high signal-to-noise ratio to detect arrhythmias. In addition, the LPD may provide cardiac pacing at the location of the implanted LPD. In some examples, one or both of the SD and the LPD may share detected signals or physiological information (e.g., R-R interval, electrogram morphology measurements, and / or electrocardiogram or electrogram), thereby enabling the device receiving such information to determine the patient's condition (e.g., determining whether the patient has an arrhythmia or a lack of synchronization between ventricles). Communication between the LPD and a subcutaneous ICD (SICD) is described in U.S. Patent Application Serial No. 13 / 756,085, filed on January 31, 2013, which is hereby incorporated by reference in its entirety.

[0119] In some examples, communication between the SICD and the IPD can be used to initiate therapy and / or confirm that therapy should be delivered. The SICD can also transmit a communication message to the LPD that instructs the LPD to change one or more parameters that define CRT therapy. In this one-way communication example, the SICD can be configured to transmit communication to the LPD, and the LPD can be configured to receive communication from the SICD. Alternatively, a one-way communication can be established such that the LPD can be configured to transmit communication to the SICD (e.g., communication from the LPD). In other examples, two-way communication can allow for confirmation of detected cardiac conditions (e.g., ventricular asynchrony, tachyarrhythmia, bradycardia, etc.) prior to delivery of any therapy. Communication between the SD and the LPD is described in detail in U.S. Patent Application Serial No. 13 / 756,085, entitled "Systems and methods for leadless pacing and shock therapy" (Attorney Docket No. C0001726.USU1), filed on May 26, 2013, which is incorporated herein by reference in its entirety.

[0120] One or more of the embodiments described herein may utilize far-field sensing to perform cardiac resynchronization pacing. In some embodiments, one or more of the electrodes of the device can be used for far-field sensing of electrical activity in different chambers. For example, a right atrial electrode or a tissue piercing electrode can be used to monitor far-field electrical activity of the right ventricle. Far-field sensing can be particularly useful in cardiac resynchronization pacing as described above. Clearance RV timing can be used to customize the timing of LV pacing for an individual patient to allow for fusion pacing (e.g., fusing RV and LV activation).

[0121] Figure 7 is a flowchart of pacing therapy method 110 for use with method 100, such as Figure 6 For example, method 110 can be used in process 104, which delivers pacing therapy to the ventricles. Method 110 can be described as an AV resynchronization therapy method.

[0122] Method 110 can include process 112, in which an atrial event is sensed. For example, the atrial event can be a right atrial event in the monitored activity of the right atrium, such as mentioned in process 102. A right atrial electrode can be used to sense the right atrial event within the monitored electrical activity of the right atrium. Additionally, or alternatively, a right atrial motion detector can be used to sense the right atrial event within the monitored mechanical activity of the right atrium. The atrial event can be determined by the controller of the medical device using a sensing circuit.

[0123] Method 110 may further include process 114, which includes waiting for a selected A-V interval to elapse in response to detecting an atrial event in process 112. For example, a controller of a medical device may wait for the selected A-V interval after detecting an atrial event.

[0124] Method 110 may further include process 116, in which ventricular pacing is delivered after the selected A-V interval in step 114 has elapsed in response to the atrial event. In some embodiments, process 116 may be performed without process 114. It is contemplated that ventricular pacing may be delivered in response to an atrial event without using the selected A-V interval.

[0125] In some embodiments, the A-V interval is configured to synchronize atrial events with ventricular events for atrioventricular synchronization. The A-V interval may also be configured or modified for improving cardiac resynchronization. For example, the A-V interval may be used to pace one or both ventricles for ventricular synchronization described in more detail below (e.g., using biventricular pacing or single ventricular pacing, such as fusion pacing).

[0126] Figure 8 is a flowchart of another illustrative pacing therapy method 120 for use with, for example, Figure 6 method 100. For example, method 120 may be used in process 104, which delivers pacing therapy to the ventricles. Method 120 may be described as an AV resynchronization therapy method.

[0127] Method 120 may include process 122, in which an atrial event is sensed within the monitored activity from process 102 ( Figure 6 ). Process 122 may be the same as or similar to process 112 ( Figure 7 ) of method 110.

[0128] Method 120 may further include process 124, in which the activity of the left ventricle is monitored. One or more tissue piercing electrodes may be used to sense the activity of the left ventricle. If more than one tissue piercing electrode is in contact with the LV myocardium, the tissue piercing electrodes may be used to sense both the LV and pace the LV.

[0129] Method 120 may further include process 126 that initiates an A-V time period. Method 120 may further include process 128 that determines whether a ventricular event is sensed in response to the activities monitored in processes 122 and 124. Specifically, process 128 may determine whether a ventricular event is sensed before the A-V time period elapses. A controller of the medical device may be used to make this determination. If no ventricular event is sensed in process 128, method 120 may branch to process 130. If a ventricular event is sensed, method 120 may branch to process 132.

[0130] Method 120 may further include process 130 in which ventricular pacing is delivered after the selected A-V time period has elapsed. Process 130 may be the same as or similar to process 114 of method 110 ( Figure 7 ). The controller of the medical device may use a therapy delivery circuit to initiate or perform ventricular pacing.

[0131] Method 120 may further include process 132 that inhibits the delivery of ventricular pacing. Inhibiting the delivery of ventricular pacing may be described as inhibiting pacing therapy.

[0132] Figure 9 is a flowchart of a tachycardia-related method 140 for use with a system 2 such as, for example, Figure 1 . For example, method 140 may be used with an intracardiac medical device 10 ( Figures 1 - 2 ) or 710 ( Figure 5 ). Method 140 may be described as a tachycardia sensing method.

[0133] Method 140 may include process 142 in which the activity of the right atrium is monitored. When implanted, the controller of the medical device may use a sensing circuit and a right atrial electrode or a right atrial motion detector to monitor the activity of the right atrium.

[0134] Method 140 may further include process 144 in which the activity of the left ventricle is monitored. When implanted, the controller of the medical device may use a sensing circuit and a tissue piercing electrode, or a left ventricular motion detector, to monitor the activity of the left ventricle.

[0135] Method 140 may further include process 146 in which tachycardia is determined based on the activities monitored in processes 142 and 144. The controller may be used to make this determination.

[0136] Figure 10 is for use with, for example, Figure 9Flowchart of a tachycardia determination method 150 for use in conjunction with, for example, method 140. For example, method 150 can be used in process 146, which determines tachycardia based on monitored activity. Method 150 can be described as a tachycardia classification method. If the monitored V rate exceeds a certain threshold (e.g., 120 bpm) or additionally or alternatively, if the monitored interval between consecutive V events is less than a certain time interval threshold (e.g., 500 ms), then a ventricular tachycardia event can be determined.

[0137] Method 150 can include process 152, which determines whether the tachycardia rhythm has a 1:1 AV conduction rhythm or characteristic. As used herein, 1:1 AV conduction or rhythm means that for each V event, there is an A event preceding it in terms of the A-V interval and in a regular pattern. The controller of the medical device can be used to make this determination. If a 1:1 AV conduction rhythm is determined, method 150 can proceed to process 154. If process 152 does not determine a 1:1 AV conduction rhythm, method 150 can proceed to process 156.

[0138] Method 150 can further include process 154, in which treatment is inhibited. For example, in response to determining that the detected rhythm is non-treatable, the controller can be used to inhibit tachycardia-related treatment.

[0139] Method 150 can further include process 156 (e.g., in response to not determining a 1:1 AV conduction rhythm in process 152), in which the type of tachycardia treatment to be delivered is determined. For example, a determination can be made that the V rate is faster than the fibrillation frequency threshold (e.g., 200 bpm), in which case the device can initiate shock therapy in process 160. If not, the device can initiate anti-tachycardia pacing therapy in process 158.

[0140] Figure 11 is a flowchart of a tachycardia treatment determination method 170 for use in conjunction with, for example, Figure 10 method 150. For example, method 170 can be used in process 156, which determines the type of tachycardia treatment to be delivered.

[0141] Method 170 may include process 172 that performs V-V event interval analysis, which includes determining parameters such as median, range, mode, and (mode - sum), or other metrics that reflect how fast the tachycardia rhythm is and how regular the intervals are between successive V events. Method 170 may further include process 174 that performs electrogram morphology analysis. This may include comparing the overall morphology or gross morphological features of different V events within the tachycardia rhythm and determining a morphological similarity index. Details for determining the morphology and frequency regularity of tachycardia events may be described in U.S. Patent No. 8,594,775 (Ghosh et al.), which is incorporated herein by reference in its entirety.

[0142] Method 170 may further include process 176 in which the frequency and rhythm regularity of the tachycardia event are determined based on a combination of monitoring the intervals between successive V events (process 172) and the corresponding electrogram morphology (process 174). In some embodiments, monomorphic VT may be determined based on the regularity of successive V events / or the similarity of the electrogram morphology corresponding to the V events, and polymorphic rhythm may be determined if neither the frequency regularity nor the morphology similarity criteria are met.

[0143] Non - limiting examples of tachycardia therapies that may be delivered include antitachycardia pacing and shock therapy (e.g., defibrillation therapy). In some embodiments, if monomorphic VT is determined, the device may initiate antitachycardia pacing (ATP). If polymorphic rhythm is determined, the device may signal an external device to deliver a shock to initiate shock therapy.

[0144] Examples of methods for determining tachycardia therapies that may be used in conjunction with the methods of the present disclosure, which include interval analysis and electrogram morphology analysis, may be described in U.S. Patent No. 7,031,711 (Brown et al.) issued on April 18, 2016, U.S. Patent No. 8,594,775 (Ghosh et al.) issued on November 26, 2013, and U.S. Patent No. 8,750,994 (Ghosh et al.) issued on June 10, 2014. Each of the above - mentioned U.S. patents is incorporated herein by reference in its entirety.

[0145] Figure 12 is a flowchart of an antitachycardia method 190 for use with a system 2 such as Figure 1 For example, method 190 may be used with an intracardiac medical device 10 and a separate medical device 50 ( Figure 1 ).

[0146] Method 190 may include process 192 that determines the presence of tachycardia. For example, a controller of a medical device may determine the presence of tachycardia based on monitored activity generated using multiple electrodes and / or one or more motion detectors. Process 192 may be the same as or similar to Figure 9 process 146 or Figure 11 process 176.

[0147] Method 190 may further include process 194 that, based on the determination of the presence of tachycardia in process 192, delivers tachycardia-related therapy using the medical device and / or a separate medical device. For example, the medical device may use one or more of the multiple electrodes to provide antitachycardia pacing.

[0148] In some embodiments, another device may perform process 192 to determine whether tachycardia has been detected, and the medical device may be used to perform process 194 to provide tachycardia-related therapy.

[0149] Figure 13 is a flowchart of a tachycardia therapy delivery method 200 for use with, for example, Figure 12 method 190. For example, method 200 may be included in process 194 of method 190, which delivers tachycardia-related therapy.

[0150] Method 200 may include process 202 that may be similar to Figure 11 process 176 that determines the type of tachycardia to be delivered. Specifically, process 202 may determine whether both the V-V event interval (determined in process 172 of method 170) and the electrogram morphology (determined in process 174 of method 170) are regular. If one or both are irregular, method 200 may continue using process 204. If both are regular, method 200 may continue using process 206.

[0151] Method 200 may further include process 204 to deliver shock therapy. Shock therapy may be initiated using the medical device. For example, the medical device may deliver a signaling pulse (e.g., a unique single, high-output pacing pulse to the ventricle) or other trigger. The pacing signal or other trigger may be detected by a separate medical device that may provide the shock.

[0152] Method 200 may further include process 206 to deliver antitachycardia pacing therapy (ATP). ATP may be delivered using multiple electrodes of the medical device. After process 206, method 200 may continue using process 208.

[0153] Method 200 may include process 208 for determining whether the V rhythm exceeds a threshold after ATP delivery has been initiated in process 206. Specifically, a V rhythm threshold may be used to distinguish monomorphic VT from other types of tachycardia in the same or a similar manner as process 156 of method 150 ( Figure 10 ). If the V rhythm exceeds the V rhythm threshold, method 200 may proceed to process 204 as described above. If the V rhythm does not exceed the V rhythm threshold, the method may proceed using process 210.

[0154] The method may further include process 210 for monitoring the tachycardia. For example, process 210 may include performing Figure 11 method 170. After process 210, method 200 may return to process 202. Method 200 may continue to loop when the V-V event intervals and electrogram morphologies are regular, e.g., unless shock therapy is delivered in process 204.

[0155] Figure 14 is a flowchart of shock therapy method 220 for use with, e.g., Figure 13 method 200. For example, method 220 may be included in process 204, which delivers shock therapy. Method 220 may be performed by a Figure 1 separate medical device 50.

[0156] Method 220 may begin with process 222, which determines whether a pacing signal has been detected. As described with respect to Figure 13 process 204, a medical device may provide a pacing signal that may be detected by a separate medical device. If no pacing signal is detected, method 220 may proceed to process 224. If a pacing signal is detected, method 220 may proceed using process 226.

[0157] Method 220 may further include process 224 for inhibiting therapy. Specifically, process 224 may inhibit a separate medical device (e.g., an extravascular ICD) from delivering shock therapy.

[0158] Method 220 may further include process 226 for delivering a shock to cardiac tissue of the patient's heart. Specifically, a separate medical device may be used to provide the shock because, for example, the medical device may not have sufficient battery capacity, size to deliver an effective cardioversion or defibrillation shock, or the positioning of the medical device may not be sufficient to deliver an effective cardioversion or defibrillation shock.

[0159] Figure 15Is a two-dimensional (2D) ventricular map 300 (e.g., top view) of a patient's heart showing a standard 17-segment view of the left ventricle 320 and the right ventricle 322. The map 300 includes a plurality of regions 326 corresponding to different zones of the human heart. As shown, the regions 326 are labeled with numbers 1-17 (which, for example, correspond to a standard 17-segment model of the human heart, corresponding to 17 segments of the left ventricle of the human heart, etc.). The regions 326 of the map 300 may include a basal anterior region 1, a basal anteroseptal region 2, a basal inferior septal region 3, a basal inferior region 4, a basal inferolateral region 5, a basal anterolateral region 6, a mid-anterior region 7, a mid-anteroseptal region 8, a mid-inferior septal region 9, a mid-inferior region 10, a mid-inferolateral region 11, a mid-anterolateral region 12, an apical anterior region 13, an apical septal region 14, an apical inferior region 15, an apical lateral region 16, and an apical region 17. Also shown are the inferior septal and anteroseptal regions of the right ventricle 322, as well as the right bundle branch (RBB) and the left bundle branch (LBB).

[0160] In some embodiments, any of the tissue-piercing electrodes of the present disclosure may be implanted in the basal region and / or septal region of the left ventricular myocardium of a patient's heart. Specifically, the tissue-piercing electrode may be implanted through the endocardium of the right atrium and the central fibrous body from the Koch triangle region of the right atrium.

[0161] Once implanted, the tissue-piercing electrode may be positioned in a target implantation zone 4( Figure 1 ) such as the basal region and / or septal region of the left ventricular myocardium. Referring to FIG. 300, the basal region includes one or more of the basal anterior region 1, the basal anteroseptal region 2, the basal inferior septal region 3, the basal inferior region 4, the mid-anterior region 7, the mid-anteroseptal region 8, the mid-inferior septal region 9, and the mid-inferior region 10. Referring to FIG. 300, the septal region includes one or more of the basal anteroseptal region 2, the basal anterior septal region 3, the mid-anteroseptal region 8, the mid-inferior septal region 9, and the apical septal region 14.

[0162] In some embodiments, when implanted, the tissue-piercing 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 basal anteroseptal region 2, the basal inferior septal region 3, the mid-anteroseptal region 8, and the mid-inferior septal region 9.

[0163] In some embodiments, when implanted, the tissue piercing electrode may be positioned in the inferior / posterior basal septal region of the left ventricular myocardium. The inferior / posterior basal septal region of the left ventricular myocardium may include a portion of at least one of the basal inferior septal region 3 and the mid-inferior septal region 9. For example, the inferior / posterior basal septal region may include the region 324 generally shown as a dashed boundary. As shown, the dashed boundary represents an approximation of the approximate location of the inferior / posterior basal septal region and may assume a slightly different shape or size depending on the particular application. Without being bound by any particular theory, stimulation of the high septal ventricular myocardium may result in intraventricular synchronous pacing and / or excitation due to the functional electrical coupling between the subendocardial Purkinje fibers and the ventricular muscle.

[0164] Figures 16 - 18 is a schematic diagram of illustrative cardiac therapy systems 402, 404, 406 that include lead medical devices 408, 418, 428 having electrodes implanted in a patient's heart 8. Many of the structures of cardiac therapy systems 402, 404, 406 may be the same as those in cardiac therapy system 2. Thus, Figures 16 - 18 many of the structures depicted in Figure 1 have the same numbers as the structures depicted in Figures 16 - 18 The description of some of the reference numerals shown in Figure 1 (e.g., separate medical device 50) may be found in the description above, particularly with respect to Figures 16 - 18 and is not repeated herein with reference to

[0165] Referring to Figure 16 , the lead medical device 408 includes one or a single implantable lead 410 that has a tissue piercing electrode 12 coupled to the distal end region of the lead and is implanted within a patient's heart 8. The housing 420 of the lead medical device 408 may be implanted and positioned external to the patient's heart 8. The lead 410 may include a right atrial electrode, and the device 408 may operate as a dual-channel support device. In some embodiments, the lead 410 may not include a right atrial electrode. That is, the lead medical device 408 may be a single-channel device that may be used for asynchronous, triggered, or other single-channel pacing. For example, when the tissue piercing electrode 12 is implanted as described above (e.g., with respect to Figure 15 FIG. 300 with respect to Figure 1 and device 10 with respect to

[0166] Referring to Figure 17, the leaded medical device 418 is similar to the leaded medical device 408, except that the device 418 includes two implantable leads 410, 412. Specifically, the implantable lead 412 may include an electrode (e.g., a right atrial electrode) coupled to the distal end region of the lead and may be implanted in a different location from the lead 410. In some embodiments, the lead 412 is implanted in a different region of the right atrium. In some embodiments, each of the leads 410, 412 may contribute one channel to the multi-channel device 418. For example, the lead 410 may sense the activity of the left ventricle (LV) or deliver pacing to the LV, and the lead 412 may sense the activity of the right atrium (RA) or deliver pacing to the RA.

[0167] Reference Figure 18 , the leaded medical device 428 is similar to the leaded medical device 418, except that the device 428 includes three implantable leads 410, 412, 414. Specifically, the implantable lead 414 may include an electrode (e.g., a right ventricular electrode) coupled to the distal end region of the lead and may be implanted in a different location from the leads 410, 412. In some embodiments, the lead 414 is implanted in a region of the right ventricle. In some embodiments, each of the leads 410, 412, 414 may contribute one channel to the multi-channel device 428. For example, the lead 410 may sense the activity of the left ventricle (LV) or deliver pacing to the LV, the lead 412 may sense the activity of the right atrium (RA) or deliver pacing to the RA, and the lead 414 may sense the activity of the right ventricle (RV) or deliver pacing to the RV.

[0168] Figure 19 is a state diagram 500 showing different illustrative treatment modes that the implantable medical devices and systems described herein may initiate or enter during operation. Such implantable medical devices and systems may have a nominal state 502 in which the device is configured to perform at least one or more of atrioventricular synchronous pacing, cardiac resynchronization pacing, and tachycardia-related therapies. The device may initiate or switch to a single-chamber pacing mode in state 504 in response to detecting atrial fibrillation. The atrial fibrillation may be detected by the device or a separate device. The device may return from state 504 to the nominal state 502.

[0169] The device can initiate or switch to the triggered pacing mode in state 506, in which the device delivers pacing in response to a trigger (e.g., a pacing signal) from a separate device (e.g., an ICD). In some embodiments, the implantable medical device can include only electrodes (e.g., tissue piercing electrodes) for pacing the LV, which are triggered by a separate, or remote, device (e.g., a subcutaneous device or a leaded device), and the separate, or remote, device determines the timing and sends commands or triggers to the implantable medical device to pace the LV to deliver CRT. The device can return from state 506 to the nominal state 502.

[0170] Further, the device can initiate or switch to the asynchronous pacing mode in state 508, in which the device delivers pacing independent of sensing in other chambers. The device can return from state 508 to the nominal state 502.

[0171] Reference will now be made to Figures 20 - 22 , which are diagrams of illustrative systems that include electrode devices. An illustrative system 1100 that includes an electrode device 1110, a display device 1130, and a computing device 1140 is depicted in Figure 20 . The illustrated electrode device 1110 includes a plurality of electrodes that are incorporated into, or included in, a band that wraps around the chest or torso of a patient 1120. The electrode device 1110 is operatively coupled to the computing device 1140 (e.g., via one or more wired electrical connections, wirelessly, etc.) to provide electrical signals from each of the electrodes to the computing device 1140 for analysis and evaluation, etc. The illustrative electrode device can be described in U.S. Patent No. 9,320,446, entitled "Bioelectric Sensor Device and Methods," issued on April 26, 2016, which is incorporated herein by reference in its entirety. Further, the illustrative electrode device 1110 will be described in more detail with reference to Figures 21 - 22 .

[0172] Although not described herein, illustrative system 1100 may further include an imaging device. The imaging device may be any type of imaging device configured to image at least a portion of the patient in a non-invasive manner or provide an image of at least a portion of the patient. For example, in addition to non-invasive tools such as contrast agents, the imaging device may not use any components or parts that can be positioned within the patient to provide an image of the patient. It should be understood that the illustrative systems, methods, and interfaces described herein may further use an imaging device to provide non-invasive assistance to a user (e.g., a physician) in combination with the evaluation of atrial-to-ventricular pacing therapy to position and place the device for delivering VfA cardiac pacing therapy and / or for positioning or selecting pacing electrodes or pacing vectors near the patient's heart for atrial-to-ventricular pacing therapy.

[0173] For example, the illustrative systems, methods, and interfaces may: provide image-guided navigation that may be used to navigate leads within the patient, the leads including leadless devices, electrodes, leadless electrodes, wireless electrodes, catheters, etc.; and also provide non-invasive cardiac therapy evaluation, including determining whether atrial-to-ventricular pacing settings are acceptable or determining whether one or more selected parameters are acceptable, such as selected location information (e.g., location information for an electrode targeted to a specific location in the left ventricle). Illustrative systems and methods using an imaging device and / or electrode device are described in U.S. Patent Publication No. 2014 / 0371832, entitled "Implantable Electrode Location Selection," filed on June 12, 2013, U.S. Patent Publication No. 2014 / 0371833, entitled "Implantable Electrode Location Selection," filed on June 12, 2013, U.S. Patent Publication No. 2014 / 0323892, entitled "Systems, Methods, and Interfaces for Identifying Effective Electrodes," filed on March 27, 2014, and U.S. Patent Publication No. 2014 / 0323882, entitled "Systems, Methods, and Interfaces for Identifying Optical Electrical Vectors," filed on March 27, 2014, each of which is incorporated herein by reference in its entirety.

[0174] An illustrative imaging device may be configured to capture X-ray images and / or any other alternative imaging modality. For example, the imaging device may be configured to capture images or image data using, for example, cinefluoroscopy, biplane fluoroscopy, ultrasound, computed tomography (CT), multislice computed tomography (MSCT), magnetic resonance imaging (MRI), high intensity focused ultrasound (HIFU), optical coherence tomography (OCT), intravascular ultrasound (IVUS), two-dimensional (2D) ultrasound, three-dimensional (3D) ultrasound, four-dimensional (4D) ultrasound, intraoperative CT, intraoperative MRI, etc. Further, it is to be understood that the imaging device may be configured to (e.g., continuously) capture multiple consecutive images to provide video frame data. That is, multiple images taken over time using the imaging device may provide video frames, or dynamic cine, data. Additionally, images may also be acquired and displayed in two, three, or four dimensions. In more advanced forms, four-dimensional surface rendering of the heart or other regions of the body may also be achieved by combining cardiac data or other soft tissue data from maps or preoperative image data captured by MRI, CT, or echocardiogram modalities. Image datasets from hybrid modalities such as positron emission tomography (PET) combined with CT, or single photon emission computed tomography (SPECT) combined with CT may also provide functional image data superimposed on anatomical data, e.g., to be used to navigate a treatment device to a target location within or near the heart or other region of interest (e.g., a location within the left ventricle, including a selected location within the high posterior basal septal region of the left ventricular cavity).

[0175] Systems and / or imaging devices that can be used in conjunction with the illustrative systems and methods described herein are described in the following applications: U.S. Patent Application Publication No. 2005 / 0008210, published Jan. 13, 2005, by Evron et al.; U.S. Patent Application Publication No. 2006 / 0074285, published Apr. 6, 2006, by Zarkh et al.; U.S. Patent Application Publication No. 2011 / 0112398, published May 12, 2011, by Zarkh et al.; U.S. Patent Application Publication No. 2013 / 0116739, published May 9, 2013, by Brada et al.; U.S. Patent No. 6,980,675, issued Dec. 27, 2005, by Evron et al.; U.S. Patent No. 7,286,866, issued Oct. 23, 2007, by Okerlund et al.; U.S. Patent No. 7,308,297, issued Dec. 11, 2011, by Reddy et al.; U.S. Patent No. 7,308,299, issued Dec. 11, 2011, by Burrell et al.; U.S. Patent No. 7,321,677, issued Jan. 22, 2008, by Evron et al.; U.S. Patent No. 7,346,381, issued Mar. 18, 2008, by Okerlund et al.; U.S. Patent No. 7,454,248, issued Nov. 18, 2008, by Burrell et al.; U.S. Patent No. 7,499,743, issued Mar. 3, 2009, by Vass et al.; U.S. Patent No. 7,565,190, issued Jul. 21, 2009, by Okerlund et al.; U.S. Patent No. 7,587,074, issued Sep. 8, 2009, by Zarkh et al.; U.S. Patent No. 7,599,730, issued Oct. 6, 2009, by Hunter et al.; U.S. Patent No. 7,613,500, issued Nov. 3, 2009, by Vass et al.; U.S. Patent No. 7,742,629, issued Jun. 22, 2010, by Zarkh et al.; U.S. Patent No. 7,747,047, issued Jun. 29, 2010, by Okerlund et al.; U.S. Patent No. 7,778,685, issued Aug. 17, 2010, by Evron et al.; U.S. Patent No. 7,778,686, issued Aug. 17, 2010, by Vass et al.; U.S. Patent No. 7,813,785, issued Oct. 12, 2010, by Okerlund et al.; U.S. Patent No. 7,996,063, issued Aug. 9, 2011, by Vass et al.; U.S. Patent No. 8,060,185, issued Nov. 15, 2011, by Hunter et al.; and U.S. Patent No. 8,401,616, issued Mar. 19, 2013, by Verard et al., each of which is incorporated herein by reference in its entirety.

[0176] The display device 1130 and the computing device 1140 may be configured to display and analyze data, such as, for example, electrical signals (e.g., electrocardiogram data), cardiac information representing at least one of mechanical cardiac function and electrical cardiac function, and the like. The cardiac information may include, for example, electrical heterogeneity information or electrical asynchrony information, alternative electrical activation information or data, etc., generated using electrical signals, which are acquired, monitored, or collected using the electrode device 1110. In at least one embodiment, the computing device 1140 may be a server, a personal computer, or a tablet computer. The computing device 1140 may be configured to receive input from the input device 1142 and transmit output to the display device 1130. Further, the computing device 1140 may include a data store that may allow access to processing programs or routines and / or one or more other types of data, e.g., for driving a graphical user interface configured to non-invasively assist a user in targeting the placement of a pacing device and / or evaluating the pacing therapy at that location (e.g., the location of an implantable electrode for pacing, the location of the pacing therapy delivered by a particular pacing vector, etc.).

[0177] The computing device 1140 may be operably coupled to the input device 1142 and the display device 1130 to, for example, transfer data to and from each of the input device 1142 and the display device 1130. For example, the computing device 1140 may be electrically coupled to each of the input device 1142 and the display device 1130 using, for example, an analog electrical connection, a digital electrical connection, a wireless connection, a bus-based connection, a network-based connection, an Internet-based connection, etc. As further described herein, a user may provide input to the input device 1142 to manipulate or modify one or more graphical depictions displayed on the display device 1130 and view and / or select one or more pieces of information related to cardiac therapy.

[0178] Although the input device 1142 is depicted as a keyboard, it should be understood that the input device 1142 can include any device capable of providing input to the computing device 1140 to perform the functions, methods, and / or logic described herein. For example, the input device 1142 can include a mouse, a trackball, a touch screen (e.g., a capacitive touch screen, a resistive touch screen, a multi-touch screen, etc.), and the like. Similarly, the display device 1130 can include any device capable of displaying information to a user, such as a graphical user interface 1132, the information including cardiac information, text instructions, graphical depictions of electrical activation information, graphical depictions of the anatomical structure of the human heart, images or graphical depictions of a patient's heart, graphical depictions of leadless and / or leaded pacing devices positioned or placed to provide VfA pacing therapy, graphical depictions of the positions of one or more electrodes, graphical depictions of the human torso, images or graphical depictions of a patient's torso, graphical depictions or actual images of implanted electrodes and / or leads, and the like. Further, the display device 1130 can include a liquid crystal display, an organic light emitting diode screen, a touch screen, a cathode ray tube display, and the like.

[0179] The processing programs or routines stored and / or executed by the computing device 1140 can include programs or routines for the following: computing mathematics, matrix mathematics, dispersion determination (e.g., standard deviation, variance, range, interquartile range, mean absolute difference, mean absolute deviation, etc.), filtering algorithms, maximum determination, minimum determination, threshold determination, moving window algorithms, decomposition algorithms, compression algorithms (e.g., data compression algorithms), calibration algorithms, image construction algorithms, signal processing algorithms (e.g., various filtering algorithms, Fourier transform, fast Fourier transform, etc.), normalization algorithms, comparison algorithms, vector mathematics, or any other processing required to implement one or more of the illustrative methods and / or processes described herein. The data stored and / or used by the computing device 1140 can include, for example, electrical signal / waveform data from the electrode device 1110, dispersion signals, windowed dispersion signals, portions or parts of various signals, electrical activation times from the electrode device 1110, graphics (e.g., graphic elements, icons, buttons, windows, dialog boxes, drop-down menus, graphic regions, graphic areas, 3D graphics, etc.), graphical user interfaces, results from one or more processing programs or routines employed in accordance with the disclosure herein (e.g., electrical signals, cardiac information, etc.), or any other data required to perform one and / or more of the processes or methods described herein.

[0180] In one or more embodiments, one or more computer programs executed on a programmable computer can be used to implement the illustrative systems, methods, and interfaces, the programmable computer such as a computer including, for example, processing capabilities, data storage (e.g., volatile or non-volatile memory and / or storage elements), input devices, and output devices. The program code and / or logic described herein can be applied to the input data to perform the functions described herein and generate the desired output information. The output information can be applied as input to one or more other devices and / or methods as described herein or as will be applied in a known manner.

[0181] Any programmable language can be used to provide one or more programs for implementing the systems, methods, and / or interfaces described herein, any such programmable language being, for example, a high-level procedural programming language and / or an object-oriented programming language suitable for communicating with a computer system. Any such program can be stored, for example, on any suitable device (e.g., storage medium) readable by a general or special purpose program, the general or special purpose program running on a computer system (e.g., including a processing device) for configuring and operating the computer system when reading the suitable device to execute the program described herein. That is, in at least one embodiment, a computer-readable storage medium configured with a computer program can be used to implement the illustrative systems, methods, and / or interfaces, wherein the storage medium so configured causes the computer to operate in a specific and predefined manner to perform the functions described herein. Further, in at least one embodiment, the illustrative systems, methods, and / or interfaces can be described as being implemented by logic (e.g., object code) encoded in one or more non-transitory media, the one or more non-transitory media including code for execution and operable, when executed by a processor, to perform operations such as the methods, procedures, and / or functions described herein.

[0182] The computing device 1140 can be, for example, any fixed or mobile computer system (e.g., a controller, a microcontroller, a personal computer, a minicomputer, a tablet computer, etc.) and can generally be described as including processing circuitry. The exact configuration of the computing device 1140 is not restrictive and can substantially be any device capable of providing suitable computing power and control capabilities (e.g., graphics processing, etc.). As described herein, a digital file can be any medium (e.g., volatile or non-volatile memory, CD-ROM, punched card, magnetically readable medium such as a disk or tape, etc.) containing digital bits (e.g., encoded in binary, ternary, etc.) that is readable and / or writable by the computing device 1140 described herein. Similarly, as described herein, a file in a user-readable format can be any data representation (e.g., ASCII text, binary numbers, hexadecimal numbers, decimal numbers, diagrams, etc.) that is readable and / or understandable by a user and can be presented on any medium (e.g., paper, display, etc.).

[0183] In view of the foregoing, it will be apparent that functions described in one or more embodiments according to the present disclosure can be implemented in any manner known to those skilled in the art. Thus, the computer language, computer system, or any other software / hardware used to implement the processes described herein should not limit the scope of the systems, processes, or programs described herein (e.g., the functions provided by such systems, processes, or programs).

[0184] The electrical activation time of a patient's heart can be useful for assessing the patient's cardiac condition and / or delivering an atrial-to-ventricular (VfA) cardiac therapy to the patient. Alternative electrical activation information or data of one or more regions of the patient's heart can be monitored or determined using an electrode device 1110 as shown in Figure 20 and Figures 21 - 22 . The illustrative electrode device 1110 can be configured to measure the body surface potential of the patient 1120, and more specifically, the torso surface potential of the patient 1120. As shown in Figure 21 , the illustrative electrode device 1110 can include a set of electrodes 1112 or an array of electrodes 1112, a strap 113, and interface / amplifier circuitry 1116. In at least one embodiment, a portion of the electrode set can be used, where the portion corresponds to a specific location on the patient's heart. The electrodes 1112 can be attached or coupled to the strap 1113 and the strap 1113 can be configured to wrap around the torso of the patient 1120 such that the electrodes 1112 encircle the patient's heart. As further shown, the electrodes 1112 can be positioned around the periphery of the patient 1120, including posterior, lateral, posterolateral, anterolateral, and anterior positions of the torso of the patient 1120.

[0185] Further, electrode 1112 can be electrically connected to interface / amplifier circuitry 1116 via a wired connection 1118. Interface / amplifier circuitry 1116 can be configured to amplify signals from electrode 1112 and provide those signals to computing device 1140. Other illustrative systems can use a wireless connection to transmit signals sensed by electrode 1112 to interface / amplifier circuitry 1116 and, in turn, to computing device 1140, e.g., as multi-channel data. For example, interface / amplifier circuitry 1116 can be electrically coupled to each of computing device 1140 and display device 1130 using, e.g., an analog electrical connection, a digital electrical connection, a wireless connection, a bus-based connection, a network-based connection, an Internet-based connection, etc.

[0186] Although in the Figure 21 example of FIG. 11A, electrode device 1110 includes strap 1113, in other examples, any one of a variety of mechanisms (e.g., tape or adhesive) can be employed to assist with the spacing and placement of electrodes 1112. In some examples, strap 1113 can include an elastic band, a strip of tape, or cloth. In other examples, electrodes 1112 can be placed individually on the torso of patient 1120. Further, in other examples, electrodes 1112 (e.g., in an array arrangement) can be part of a patch, a vest, or positioned within a patch, a vest, and / or other means of securing electrodes 1112 to the torso of patient 1120.

[0187] Electrodes 1112 can be configured to surround the heart of patient 1120 and record or monitor electrical signals after they have propagated through the torso of patient 1120 and are associated with depolarization and repolarization of the heart. Each of electrodes 1112 can be used in a unipolar configuration to sense the torso surface potential reflective of cardiac signals. Interface / amplifier circuitry 1116 can also be coupled to a return electrode or neutral electrode (not shown) that can be used in combination with each electrode 1112 for unipolar sensing. In some examples, there can be from about 12 to about 50 electrodes 1112 spatially distributed around the patient's torso. Other configurations can have more or fewer electrodes 1112.

[0188] The computing device 1140 can record and analyze the electrical activity (e.g., torso surface potential signals) sensed by the electrodes 1112 and amplified / conditioned by the interface / amplifier circuitry 1116. The computing device 1140 can be configured to analyze the signals from the electrodes 1112 to provide them as anterior electrode signals and posterior electrode signals, as well as surrogate cardiac electrical activation times, where the surrogate cardiac electrical activation times represent, for example, the actual or local electrical activation times of one or more regions of the patient's heart, as will be further described below. The computing device 1140 can be configured to analyze the signals from the electrodes 1112 to provide them as anterior septal electrode signals, as well as surrogate cardiac electrical activation times, where the surrogate cardiac electrical activation times represent, for example, the actual or local electrical activation times of one or more anterior septal regions of the patient's heart, as will be further described below, e.g., for evaluating VfA pacing therapy. Further, the electrical signals measured at the left anterior surface location of the patient's torso can represent, or can be a surrogate for, the electrical signals of the left anterior left ventricular region of the patient's heart; the electrical signals measured at the left lateral surface location of the patient's torso can represent, or can be a surrogate for, the electrical signals of the left lateral left ventricular region of the patient's heart; the electrical signals measured at the left posterolateral surface location of the patient's torso can represent, or can be a surrogate for, the electrical signals of the posterolateral left ventricular region of the patient's heart; and the electrical signals measured at the posterior surface location of the patient's torso can represent, or can be a surrogate for, the electrical signals of the posterior left ventricular region of the patient's heart. In one or more embodiments, the measurement of the activation time can be performed by measuring the time period between the onset of cardiac depolarization (e.g., onset of the QRS complex) and an appropriate reference point, where the appropriate reference point is, for example, a peak, minimum, minimum slope, maximum slope, zero crossing, threshold crossing, etc.

[0189] Additionally, the computing device 1140 can be configured to provide a graphical user interface that depicts the surrogate electrical activation times obtained using the electrode device 1110. Exemplary systems, methods, and / or interfaces can non-invasively use the electrical information collected by using the electrode device 1110 to evaluate the patient's cardiac condition and / or to deliver atrial-to-ventricular pacing therapy to the patient.

[0190] Figure 22Another illustrative electrode device 1110 is shown that includes a plurality of electrodes 1112 configured to surround a patient's 1120 heart and record or monitor electrical signals after the electrical signals associated with depolarization and repolarization of the heart have propagated through the patient's 1120 torso. The electrode device 1110 may include a vest 1114 to which the plurality of electrodes 1112 may be attached or the electrodes 1112 may be coupled to the vest 114. In at least one embodiment, the plurality of electrodes 1112 or an array of electrodes 112 may be used to collect electrical information such as, for example, surrogate electrical activation times. Similar to the electrode device 1110 of Figure 21 The electrode device 1110 may include an interface / amplifier circuitry 1116 that is electrically coupled to each of the electrodes 1112 by a wired connection 1118 and configured to transmit signals from the electrodes 1112 to a computing device 1140. As shown, the electrodes 1112 may be distributed over the patient's 1120 torso, including, for example, the front surface, side surfaces, posterolateral surfaces, anterolateral surfaces, and back surface of the patient's 1120 torso. Figure 22 Similar to the electrode device 1110 of

[0191] The vest 1114 may be formed of a knitted fabric to which the electrodes 1112 are attached. The vest 1114 may be configured to maintain the position and spacing of the electrodes 1112 on the patient's 1120 torso. Further, the vest 1114 may be marked to assist in determining the position of the electrodes 1112 on the patient's 1120 torso surface. In one or more embodiments, the vest 1114 may include 17 or more anterior electrodes that may be positioned proximate the patient's anterior torso and may include 39 or more posterior electrodes that may be positioned proximate the patient's anterior torso. In some examples, there may be from about 25 electrodes 1112 to about 256 electrodes 1112 distributed around the patient's 1120 torso, but other configurations may have more or fewer electrodes 1112.

[0192] As described herein, the electrode device 1110 may be configured to measure electrical information (e.g., electrical signals) representative of different regions of a patient's heart. For example, the activation times of different regions of a patient's heart may be roughly estimated based on surface electrocardiogram (ECG) activation times measured using surface electrodes near surface regions corresponding to different regions of the patient's heart. In at least one example, the activation time of the anterior septal region of a patient's heart may be roughly estimated based on surface ECG activation times measured using surface electrodes near a surface region corresponding to the anterior septal region of the patient's heart. That is, a portion of the electrode set 1112 rather than the entire electrode set may be used to generate an activation time corresponding to a particular location of the patient's heart corresponding to that portion of the electrode set.

[0193] Exemplary systems, methods, and interfaces can be used to provide non-invasive assistance to a user when evaluating a patient's cardiac health or condition and / or when evaluating cardiac therapy, such as atrial-to-ventricular (VfA) pacing therapy (e.g., the cardiac therapy currently being delivered to the patient during or after implantation) using an electrode device 1110. Further, the exemplary systems, methods, and interfaces can be used to assist a user in configuring a cardiac therapy (such as VfA pacing therapy) being delivered to a patient.

[0194] VfA pacing can be described as providing synchronous homogeneous excitation of the ventricles of the heart. As an example, a patient with atrioventricular (AV) block or prolonged AV timing that can lead to heart failure (who would have a complete (e.g., normal) QRS if not having AV block or prolonged AV timing) can benefit from VfA pacing therapy. Additionally, as an example, VfA pacing can provide beneficial excitation for a heart failure patient with an inherent ventricular conduction disorder. Further, appropriately placed VfA pacing can provide optimal ventricular excitation for such patients. Further, left ventricular (LV) resynchronization for a heart failure patient with left bundle branch block (LBBB) can find that VfA pacing enables easier access to the left ventricular endocardium without the need to expose a leadless device or a lead to the endocardial blood pool. At the same time, in this example, this can help involve a part of the conduction system to possibly correct the LBBB and effectively resynchronize the patient.

[0195] Figure 23 An exemplary method 600 for detecting atrial activity using, for example, Figure 2 a motion detector 11 is shown. Specifically, method 600 can include detecting atrial contraction based on an analysis of a motion signal (e.g., provided by the motion detector 11) that can be performed by an IMD implanted in a patient's heart. In some embodiments, the motion signal can be provided by an IMD implanted within a ventricle (such as the right ventricle) of the patient's heart. Method 600 can include starting an atrial contraction detection delay period (630) when a ventricular excitation event is identified. Method 600 can include starting an atrial contraction detection window (632) when the atrial contraction delay period expires. Method 600 can include analyzing the motion signal within the atrial contraction detection window.

[0196] Method 600 may include: filtering a motion signal within an atrial contraction detection window, rectifying the filtered signal, and generating a derivative signal of the filtered and rectified motion signal within the atrial contraction detection window (634). Method 600 may include determining whether an amplitude of the derivative signal within the atrial contraction detection window exceeds a threshold (636). In response to determining that the amplitude of the derivative signal within the atrial contraction detection window exceeds the threshold (i.e., the "yes" branch of 636), method 600 may proceed to detect an atrial contraction (638). Otherwise (i.e., the "no" branch of 636), method 600 may return to filtering, rectifying, and generating the derivative signal (634). Various techniques for using a motion detector that provides a motion signal may be described in U.S. Patent No. 9,399,140 (Cho et al.) entitled "Atrial contraction detection by aventricular leadless pacing device for atrio-synchronous ventricular pacing," issued on July 26, 2016, which is incorporated herein by reference in its entirety. Exemplary embodiments

[0197] However, the present disclosure is not limited thereto, and various aspects of the disclosure of the present application can be obtained through discussion of some exemplary embodiments provided below.

[0198] Various exemplary embodiments relate to atrioventricular synchronous pacing.

[0199] In illustrative embodiment 1, an implantable medical device includes a plurality of electrodes. The plurality of electrodes includes a tissue piercing electrode that is implantable through the endocardium of the right atrium and the central fibrous body from the Koch triangle region of the right atrium for delivering cardiac therapy and sensing at least one of the electrical activity of the left ventricle in the basal region and / or septal region of the left ventricular myocardium of a patient's heart. The plurality of electrodes further includes a right atrial electrode that can be positioned within the right atrium for delivering cardiac therapy and sensing at least one of the electrical activity of the right atrium of a patient's heart. The implantable medical device further includes: a therapy delivery circuit operably coupled to the plurality of electrodes for delivering cardiac therapy to a patient's heart; and a sensing circuit operably coupled to the plurality of electrodes for sensing the electrical activity of a patient's heart. The implantable medical device further includes a controller that includes processing circuitry operably coupled to the therapy delivery circuit and the sensing circuit. The controller is configured to: monitor the electrical activity of the right atrium using the right atrial electrode; and deliver atrioventricular synchronous pacing based on the monitored electrical activity of the right atrium using at least the tissue piercing electrode implanted through the endocardium of the right atrium and the central fibrous body from the Koch triangle region of the right atrium into the basal region and / or septal region of the left ventricular myocardium of a patient's heart to pace one or both ventricles.

[0200] In illustrative embodiment 2, a method includes: monitoring the activity of the right atrium of a patient's heart using a right atrial electrode or a right atrial motion detector; and delivering atrioventricular synchronous pacing based on the monitored activity of the right atrium using at least a tissue piercing electrode implanted through the endocardium of the right atrium and the central fibrous body from the Koch triangle region of the right atrium into the basal region and / or septal region of the left ventricular myocardium of a patient's heart, including pacing one or both ventricles using the at least one tissue piercing electrode.

[0201] In illustrative embodiment 3, the device or method of any of the foregoing illustrative embodiments is included, wherein delivering atrioventricular synchronous pacing includes pacing the right atrium using the right atrial electrode.

[0202] In illustrative embodiment 4, the device or method of any of the foregoing illustrative embodiments is included, wherein delivering atrioventricular synchronous pacing based on the monitored electrical activity of the right atrium using at least a tissue piercing electrode implanted through the endocardium of the right atrium and the central fibrous body from the Koch triangle region of the right atrium into the basal region and / or septal region of the left ventricular myocardium of a patient's heart to pace one or both ventricles includes: sensing atrial events within the monitored electrical activity of the right atrium; and delivering pacing to one or both ventricles in response to the sensed atrial events.

[0203] In illustrative embodiment 5, the apparatus or method of illustrative embodiment 4 is included, wherein delivering pacing to one or both ventricles in response to a sensed atrial event includes: delivering pacing to one or both ventricles after a selected A-V interval has elapsed since the sensed atrial event.

[0204] In illustrative embodiment 6, the apparatus or method of any of the foregoing illustrative embodiments is included, wherein the controller is further configured to perform, or the method further includes: monitoring electrical activity of the left ventricle in the basal region and / or septal region of the left ventricular myocardium of a patient using a tissue piercing electrode implanted through the endocardium of the right atrium and the central fibrous body from the Koch triangle region of the right atrium into the basal region and / or septal region of the left ventricular myocardium; sensing ventricular events within the electrical activity monitored using the tissue piercing electrode; and inhibiting delivery of pacing to one or both ventricles in response to sensing a ventricular event within the electrical activity monitored using the tissue piercing electrode.

[0205] In illustrative embodiment 7, the apparatus or method of any of the foregoing illustrative embodiments is included, wherein the controller is further configured to, or the method further includes: detecting atrial fibrillation and initiating a single chamber pacing mode.

[0206] In illustrative embodiment 8, the apparatus or method of any of the foregoing illustrative embodiments is included, wherein the controller is further configured to, or the method further includes: receiving a trigger from a separate medical device in a triggered pacing mode.

[0207] In illustrative embodiment 8, the apparatus or method of any of the foregoing illustrative embodiments is included, wherein the controller is further configured to, or the method further includes: delivering pacing in an asynchronous pacing mode.

[0208] In illustrative embodiment 9, the apparatus of any of the foregoing illustrative embodiments is included and further includes a housing extending from a proximal end region to a distal end region. The right atrial electrode is coupled to the housing leadless, and the tissue piercing electrode is coupled to the distal end region of the housing leadless. A therapy delivery circuit, a sensing circuit, and a controller are positioned within the housing.

[0209] In illustrative embodiment 10, the apparatus of illustrative embodiment 9 is included and further includes a fixation member extending from the housing. The fixation member is configured to pierce into the myocardium. The fixation member extends from the distal end region of the housing toward the distal tip of the tissue piercing electrode.

[0210] In illustrative embodiment 11, the device including any of the foregoing illustrative embodiments further includes a housing, wherein the therapy delivery circuit, the sensing circuit, and the controller are positioned within the housing. The device further includes a lead coupled to the housing and extending from the housing to a distal end region. The tissue piercing electrode and the right atrial electrode are coupled to the distal end region of the lead.

[0211] In illustrative embodiment 12, the device including any of the foregoing illustrative embodiments further includes a housing, wherein the therapy delivery circuit, the sensing circuit, and the controller are positioned within the housing. The device further includes a first lead coupled to the housing and extending from the housing to a first distal end region, and a second lead coupled to the housing and extending from the housing to a second distal end region. The tissue piercing electrode is coupled to the first distal end region of the first lead. The right atrial electrode is coupled to the second distal end region of the second lead.

[0212] In illustrative embodiment 13, the device including any of the foregoing illustrative embodiments further includes a housing, wherein the therapy delivery circuit, the sensing circuit, and the controller are positioned within the housing. The device further includes: a first lead coupled to the housing and extending from the housing to a first distal end region, a second lead coupled to the housing and extending from the housing to a second distal end region, and a third lead coupled to the housing and extending from the housing to a third distal end region. The plurality of electrodes further includes a right ventricular electrode that is coupled to the third distal end region of the third lead and is configured to deliver cardiac therapy to the right ventricle of the patient's heart or sense the electrical activity of the right ventricle of the patient's heart. The tissue piercing electrode is coupled to the first distal end region of the first lead. The right atrial electrode is coupled to the second distal end region of the second lead.

[0213] In illustrative embodiment 14, an implantable medical device includes a housing extending from a proximal end region to a distal end region. The device also includes a plurality of electrodes. The plurality of electrodes includes a tissue piercing electrode that is leadless coupled to the distal end region of the housing and is implantable through the endocardium of the right atrium and the central fibrous body from the Koch triangle region of the right atrium for delivering cardiac therapy to the left ventricle or sensing electrical activity of the left ventricle in a basal region and / or a septal region of the left ventricular myocardium of a patient's heart. The plurality of electrodes also includes a right atrial electrode that is leadless coupled to the housing and is positionable within the right atrium for delivering cardiac therapy to the right atrium of a patient's heart or sensing electrical activity of the right atrium of a patient's heart. The implantable medical device further includes a therapy delivery circuit within the housing that is operably coupled to the plurality of electrodes for delivering cardiac therapy to a patient's heart; and a sensing circuit within the housing that is operably coupled to the plurality of electrodes for sensing electrical activity of a patient's heart. The implantable medical device further includes a controller that includes processing circuitry within the housing that is operably coupled to the therapy delivery circuit and the sensing circuit. The controller is configured to: monitor electrical activity of the right atrium using the right atrial electrode; and deliver atrioventricular synchronous pacing based on the monitored electrical activity of the right atrium using at least the tissue piercing electrode that is implanted through the endocardium of the right atrium and the central fibrous body from the Koch triangle region of the right atrium in a basal region and / or a septal region of the left ventricular myocardium of a patient's heart to pace one or both ventricles.

[0214] In illustrative embodiment 15, an implantable medical device includes a plurality of electrodes. The plurality of electrodes includes a tissue piercing electrode that is implantable through the endocardium of the right atrium and the central fibrous body from the Koch triangle region of the right atrium for delivering at least one of cardiac therapy and sensing electrical activity of the left ventricle in a basal region and / or a septal region of the left ventricular myocardium of a patient's heart. The tissue piercing electrode also includes a right atrial motion detector that is positionable within the right atrium for sensing mechanical activity of the right atrium of a patient's heart. The implantable medical device further includes a therapy delivery circuit that is operably coupled to the plurality of electrodes for delivering cardiac therapy to a patient's heart; and a sensing circuit that is operably coupled to the plurality of electrodes for sensing electrical activity of a patient's heart. The implantable medical device further includes a controller that includes processing circuitry operably coupled to the therapy delivery circuit and the sensing circuit. The controller is configured to: monitor mechanical activity of the right atrium using the right atrial motion detector; and deliver atrioventricular synchronous pacing based on the monitored mechanical activity of the right atrium using at least the tissue piercing electrode that is implanted through the endocardium of the right atrium and the central fibrous body from the Koch triangle region of the right atrium in a basal region and / or a septal region of the left ventricular myocardium of a patient's heart to pace one or both ventricles.

[0215] Various illustrative embodiments relate to cardiac resynchronization pacing.

[0216] In illustrative embodiment 16, an implantable medical device includes a plurality of electrodes. The plurality of electrodes includes a tissue piercing electrode that is implantable through the endocardium of the right atrium and the central fibrous body from the Koch triangle region of the right atrium for delivering cardiac therapy to the left ventricle and / or sensing at least one of the electrical activity of the left ventricle in a basal region and / or a septal region of the left ventricular myocardium of a patient's heart. The plurality of electrodes further includes a right atrial electrode that can be positioned within the right atrium for delivering cardiac therapy to the right atrium of a patient's heart and / or sensing at least one of the electrical activity of the right atrium of a patient's heart. The implantable medical device further includes: a therapy delivery circuit operably coupled to the plurality of electrodes for delivering cardiac therapy to a patient's heart; and a sensing circuit operably coupled to the plurality of electrodes for sensing the electrical activity of a patient's heart. The implantable medical device further includes a controller that includes a processing circuitry operably coupled to the therapy delivery circuit and the sensing circuit. The controller is configured to perform at least one of the following: monitor the electrical activity of the right atrium using the right atrial electrode; and monitor the electrical activity of the left ventricle using the tissue piercing electrode implanted through the endocardium of the right atrium and the central fibrous body from the Koch triangle region of the right atrium in a basal region and / or a septal region of the left ventricular myocardium of a patient's heart. The controller is further configured to deliver cardiac resynchronization pacing based on the monitored electrical activity using at least the tissue piercing electrode implanted through the endocardium of the right atrium and the central fibrous body from the Koch triangle region of the right atrium in a basal region and / or a septal region of the left ventricular myocardium of a patient's heart to pace one or both ventricles.

[0217] In illustrative embodiment 17, a method includes at least one of the following: monitor the electrical activity of the right atrium of a patient's heart using a right atrial electrode; and monitor the electrical activity of the left ventricle using a tissue piercing electrode implanted through the endocardium of the right atrium and the central fibrous body from the Koch triangle region of the right atrium in a basal region and / or a septal region of the left ventricular myocardium of a patient's heart. The method further includes: delivering cardiac resynchronization pacing based on the monitored electrical activity using at least the tissue piercing electrode implanted through the endocardium of the right atrium and the central fibrous body from the Koch triangle region of the right atrium in a basal region and / or a septal region of the left ventricular myocardium of a patient's heart, including pacing one or both ventricles.

[0218] In illustrative embodiment 18, the device or method of any of the foregoing illustrative embodiments is included, wherein the controller is further configured to, or the method further includes: monitor the far-field electrical activity of the right ventricle using the right atrial electrode.

[0219] In illustrative embodiment 19, a device or method of any one of illustrative embodiments 16 - 18 is included, wherein delivering cardiac resynchronization pacing based on monitored electrical activity using at least a tissue piercing electrode implanted from the Koch triangle region of the right atrium through the endocardium of the right atrium and the central fibrous body into the basal region and / or septal region of the left ventricular myocardium of a patient's heart to pace one or both ventricles includes: sensing atrial events within the monitored electrical activity of the right atrium; and delivering pacing to one or both ventricles in response to the sensed atrial events to provide cardiac resynchronization.

[0220] In illustrative embodiment 20, a device or method of any one of illustrative embodiments 16 - 19 is included, wherein delivering cardiac resynchronization pacing based on monitored electrical activity using at least a tissue piercing electrode implanted from the Koch triangle region of the right atrium through the endocardium of the right atrium and the central fibrous body into the basal region and / or septal region of the left ventricular myocardium of a patient's heart to pace one or both ventricles includes: sensing ventricular events within the electrical activity monitored using the tissue piercing electrode; and delivering pacing to one or both ventricles in response to the sensed ventricular events to provide cardiac resynchronization.

[0221] In illustrative embodiment 21, a device or method of illustrative embodiment 20 is included, wherein delivering pacing to one or both ventricles in response to the sensed ventricular events includes: delivering pacing to one or both ventricles after a selected time period has elapsed since the sensed ventricular event.

[0222] In illustrative embodiment 22, a device or method of any one of illustrative embodiments 16 - 21 is included, wherein the controller is further configured to, or the method further includes: detecting atrial fibrillation and initiating a single chamber pacing mode.

[0223] In illustrative embodiment 23, a device or method of any one of illustrative embodiments 16 - 22 is included, wherein the controller is further configured to, or the method further includes: receiving a trigger from a separate medical device in a triggered pacing mode.

[0224] In illustrative embodiment 24, a device or method of any one of illustrative embodiments 16 - 23 is included, wherein the controller is further configured to, or the method further includes: delivering pacing in an asynchronous pacing mode.

[0225] In illustrative embodiment 25, a device of any one of illustrative embodiments 16 - 24 is included, further including a housing extending from a proximal end region to a distal end region. The right atrial electrode is wirelessly coupled to the housing, and the tissue piercing electrode is wirelessly coupled to the distal end region of the housing. The therapy delivery circuit, sensing circuit, and controller are positioned within the housing.

[0226] In illustrative embodiment 26, the device of illustrative embodiment 25 is included and further includes a fixation member extending from the housing. The fixation member is configured to pierce into the myocardium. The fixation member extends from the distal end region of the housing towards the distal tip of the tissue piercing electrode.

[0227] In illustrative embodiment 27, the device of any one of illustrative embodiments 16 - 26 is included and further includes a housing, wherein the therapy delivery circuit, the sensing circuit, and the controller are positioned within the housing. The device further includes a lead coupled to the housing and extending from the housing to a distal end region. The tissue piercing electrode and the right atrial electrode are coupled to the distal end region of the lead.

[0228] In illustrative embodiment 28, the device of any one of illustrative embodiments 16 - 27 is included and further includes a housing, wherein the therapy delivery circuit, the sensing circuit, and the controller are positioned within the housing. The device further includes a first lead coupled to the housing and extending from the housing to a first distal end region, and a second lead coupled to the housing and extending from the housing to a second distal end region. The tissue piercing electrode is coupled to the first distal end region of the first lead. The right atrial electrode is coupled to the second distal end region of the second lead.

[0229] In illustrative embodiment 29, the device of any one of illustrative embodiments 16 - 28 is included and further includes a housing, wherein the therapy delivery circuit, the sensing circuit, and the controller are positioned within the housing. The device further includes a first lead coupled to the housing and extending from the housing to a first distal end region, a second lead coupled to the housing and extending from the housing to a second distal end region, and a third lead coupled to the housing and extending from the housing to a third distal end region. The plurality of electrodes further includes a right ventricular electrode that is coupled to the third distal end region of the third lead and is configured to deliver cardiac therapy to the right ventricle of the patient's heart or sense the electrical activity of the right ventricle of the patient's heart. The tissue piercing electrode is coupled to the first distal end region of the first lead. The right atrial electrode is coupled to the second distal end region of the second lead.

[0230] In illustrative embodiment 30, an implantable medical device includes a housing extending from a proximal end region to a distal end region. The implantable medical device also includes a plurality of electrodes. The plurality of electrodes includes a tissue piercing electrode that is leadless and coupled to the distal end region of the housing and is implantable through the endocardium of the right atrium and the central fibrous body from the Koch triangle region of the right atrium for delivering cardiac therapy to the left ventricle or sensing electrical activity of the left ventricle in a basal region and / or a septal region of the left ventricular myocardium of a patient's heart. The plurality of electrodes also includes a right atrium electrode that is leadless and coupled to the housing and is positionable within the right atrium for delivering cardiac therapy to the right atrium of a patient's heart or sensing electrical activity of the right atrium of a patient's heart. The implantable medical device further includes: a therapy delivery circuit within the housing that is operably coupled to the plurality of electrodes for delivering cardiac therapy to a patient's heart; a sensing circuit within the housing that is operably coupled to the plurality of electrodes for sensing electrical activity of a patient's heart. The implantable medical device further includes a controller that includes processing circuitry within the housing that is operably coupled to the therapy delivery circuit and the sensing circuit. The controller is configured to perform at least one of the following: monitor electrical activity of the right atrium using the right atrium electrode; and monitor electrical activity of the left ventricle using the tissue piercing electrode that extends from the Koch triangle region of the right atrium through the endocardium of the right atrium and the central fibrous body into a basal region and / or a septal region of the left ventricular myocardium of a patient's heart. The controller is further configured to deliver cardiac resynchronization pacing based on the monitored electrical activity using at least the tissue piercing electrode that extends from the Koch triangle region of the right atrium through the endocardium of the right atrium and the central fibrous body and is implanted in a basal region and / or a septal region of the left ventricular myocardium of a patient's heart to pace one or both ventricles.

[0231] In illustrative embodiment 31, an implantable medical device includes a plurality of electrodes. The plurality of electrodes includes a tissue piercing electrode that is implantable through the endocardium of the right atrium and the central fibrous body from the Koch triangle region of the right atrium for delivering cardiac therapy and / or sensing electrical activity of the left ventricle in a basal region and / or a septal region of the left ventricular myocardium of a patient's heart. The plurality of electrodes further includes a right atrium motion detector that is positionable within the right atrium for sensing mechanical activity of the right atrium of the patient's heart. The implantable medical device further includes a therapy delivery circuit operatively coupled to the plurality of electrodes for delivering cardiac therapy to the patient's heart and a sensing circuit operatively coupled to the plurality of electrodes for sensing electrical activity of the patient's heart. The implantable medical device further includes a controller that includes processing circuitry operatively coupled to the therapy delivery circuit and the sensing circuit. The controller is configured to monitor mechanical activity of the right atrium using the right atrium motion detector and deliver cardiac resynchronization pacing based on the monitored mechanical activity of the right atrium using at least the tissue piercing electrode that is implanted through the endocardium of the right atrium and the central fibrous body from the Koch triangle region of the right atrium in a basal region and / or a septal region of the left ventricular myocardium of the patient's heart to pace one or both ventricles.

[0232] Various illustrative embodiments relate to tachycardia therapy.

[0233] In illustrative embodiment 32, an implantable medical device includes a plurality of electrodes. The plurality of electrodes includes a tissue piercing electrode that is implantable through the endocardium of the right atrium and the central fibrous body from the Koch triangle region of the right atrium for delivering cardiac therapy or sensing electrical activity of the left ventricle in a basal region and / or a septal region of the left ventricular myocardium of a patient's heart. The plurality of electrodes further includes a right atrium electrode that is positionable within the right atrium for delivering cardiac therapy or sensing electrical activity of the right atrium of the patient's heart. The implantable medical device further includes a therapy delivery circuit operatively coupled to the plurality of electrodes for delivering cardiac therapy to the patient's heart and a sensing circuit operatively coupled to the plurality of electrodes for sensing electrical activity of the patient's heart. The implantable medical device further includes a controller that includes processing circuitry operatively coupled to the therapy delivery circuit and the sensing circuit. The controller is configured to monitor electrical activity of the right atrium using the right atrium electrode, monitor electrical activity of the left ventricle using the tissue piercing electrode that is implanted through the endocardium of the right atrium and the central fibrous body from the Koch triangle region of the right atrium in a basal region and / or a septal region of the left ventricular myocardium of the patient's heart to sense electrical activity of the left ventricle in the basal region and / or the septal region of the left ventricular myocardium, and deliver tachycardia therapy based on the monitored electrical activity of the right atrium and the left ventricle.

[0234] In illustrative embodiment 33, a method includes: monitoring electrical activity of a right atrium of a patient's heart using a right atrial electrode; monitoring electrical activity of a left ventricle of the patient's heart using a tissue piercing electrode that is implanted from a Koch triangle region of the right atrium through the right atrial endocardium and the central fibrous body into a basal region and / or a septal region of a left ventricular myocardium of the patient's heart to sense electrical activity of the left ventricle in the basal region and / or the septal region of the left ventricular myocardium; and delivering tachycardia therapy based on the monitored electrical activity of the right atrium and the left ventricle.

[0235] In illustrative embodiment 34, an apparatus or method includes any one of illustrative embodiments 32-33, wherein the controller is configured to perform, or the method further includes: delivering tachycardia therapy based on the monitored electrical activity of the right atrium and the left ventricle includes at least one of the following: delivering antitachycardia pacing therapy using a plurality of electrodes, and delivering shock therapy using a separate medical device.

[0236] In illustrative embodiment 35, an apparatus or method includes any one of illustrative embodiments 32-34, wherein the controller is further configured to perform, or the method further includes: inhibiting tachycardia therapy in response to determining that the cardiac rhythm of the patient's heart has 1:1 atrioventricular conduction.

[0237] In illustrative embodiment 36, an apparatus including any one of illustrative embodiments 32-35 further includes a housing extending from a proximal end region to a distal end region, wherein the right atrial electrode is wirelessly coupled to the housing, and the tissue piercing electrode is wirelessly coupled to the distal end region of the housing, wherein a therapy delivery circuit, a sensing circuit, and a controller are enclosed within the housing.

[0238] In illustrative embodiment 37, the apparatus including the illustrative embodiment 36 further includes a fixation member extending from the housing. The fixation member is configured to pierce into the myocardium. The fixation member extends from the distal end region of the housing toward the distal tip of the tissue piercing electrode.

[0239] In illustrative embodiment 38, an apparatus including any one of illustrative embodiments 32-37 further includes a housing, wherein the therapy delivery circuit, the sensing circuit, and the controller are positioned within the housing. The apparatus further includes a lead coupled to the housing and extending from the housing to a distal end region. The tissue piercing electrode and the right atrial electrode are coupled to the distal end region of the lead.

[0240] In illustrative embodiment 39, the device includes any one of the devices of illustrative embodiments 32 - 38 and further includes a housing within which the therapy delivery circuit, the sensing circuit, and the controller are located. The device further includes: a first lead coupled to the housing and extending from the housing to a first distal end region, and a second lead coupled to the housing and extending from the housing to a second distal end region. A tissue piercing electrode is coupled to the first distal end region of the first lead. A right atrial electrode is coupled to the second distal end region of the second lead.

[0241] In illustrative embodiment 40, the device includes any one of the devices of illustrative embodiments 32 - 39 and further includes a housing within which the therapy delivery circuit, the sensing circuit, and the controller are located. The device further includes: a first lead coupled to the housing and extending from the housing to a first distal end region, a second lead coupled to the housing and extending from the housing to a second distal end region, and a third lead coupled to the housing and extending from the housing to a third distal end region. The plurality of electrodes further includes a right ventricular electrode that is coupled to the third distal end region of the third lead and is configured to deliver cardiac therapy to or sense the electrical activity of the right ventricle of the patient's heart. A tissue piercing electrode is coupled to the first distal end region of the first lead. A right atrial electrode is coupled to the second distal end region of the second lead.

[0242] In illustrative embodiment 41, an implantable medical device includes a plurality of electrodes. The plurality of electrodes includes a tissue piercing electrode that is implantable through the endocardium of the right atrium and the central fibrous body from the Koch triangle region of the right atrium for delivering cardiac therapy to or sensing the electrical activity of the left ventricle in the basal region and / or septal region of the left ventricular myocardium of the patient's heart. The plurality of electrodes further includes a right atrial electrode that is positionable within the right atrium for delivering cardiac therapy to or sensing the electrical activity of the right atrium of the patient's heart. The implantable medical device further includes: a therapy delivery circuit operably coupled to the plurality of electrodes for delivering cardiac therapy to the patient's heart; and a sensing circuit operably coupled to the plurality of electrodes for sensing the electrical activity of the patient's heart. The implantable medical device further includes a controller that includes a processing circuitry operably coupled to the therapy delivery circuit and the sensing circuit. The controller is configured to: monitor the electrical activity of the right atrium using the right atrial electrode; monitor the electrical activity of the left ventricle using the tissue piercing electrode that is implanted in the basal region and / or septal region of the left ventricular myocardium of the patient's heart through the endocardium of the right atrium and the central fibrous body from the Koch triangle region of the right atrium to sense the electrical activity of the left ventricle; and determine tachycardia of the patient's heart based on the monitored electrical activities of the right atrium and the left ventricle.

[0243] In illustrative embodiment 42, a method includes: monitoring electrical activity of a patient's heart's right atrium using a right ventricular electrode; monitoring electrical activity of a patient's heart's left ventricle using a tissue piercing electrode that is implanted from the Koch triangle region of the right atrium through the right atrial endocardium and the central fibrous body into the basal region and / or septal region of the left ventricular myocardium of the patient's heart to sense electrical activity of the left ventricle; and determining tachycardia of the patient's heart based on the monitored electrical activity of the right atrium and left ventricle.

[0244] In illustrative embodiment 43, the apparatus or method of any one of illustrative embodiments 41-42 is included, wherein the controller is further configured to perform, or the method further includes: determining whether the heart rhythm of the patient's heart has 1:1 atrioventricular conduction.

[0245] In illustrative embodiment 44, the apparatus or method of illustrative embodiment 43 is included, wherein the controller is further configured to perform, or the method further includes: determining an appropriate tachycardia treatment based on the monitored electrical activity of the right atrium and left ventricle in response to the heart rhythm not having 1:1 atrioventricular conduction.

[0246] In illustrative embodiment 45, the apparatus or method of any one of illustrative embodiments 41-44 is included, wherein determining tachycardia of the patient's heart based on the monitored electrical activity of the right atrium and left ventricle includes: determining that the atrial rhythm is regular, and determining that the ventricular rhythm exceeds a selected ventricular rhythm threshold.

[0247] In illustrative embodiment 46, the apparatus or method of any one of illustrative embodiments 41-45 is included, wherein the controller is further configured to, or the method further includes: delivering a tachycardia treatment in response to determining tachycardia of the patient's heart.

[0248] In illustrative embodiment 47, the apparatus or method of illustrative embodiment 46 is included, wherein the controller is further configured to perform, or the method further includes: delivering antitachycardia pacing treatment in response to regular V-V event intervals and regular electrogram morphologies.

[0249] In illustrative embodiment 48, the apparatus or method of any one of illustrative embodiments 46-47 is included, wherein the controller is further configured to perform, or the method further includes: delivering shock treatment using a separate medical device in response to at least one of irregular V-V event intervals and irregular electrogram morphologies.

[0250] In illustrative embodiment 49, an implantable medical device includes a plurality of electrodes. The plurality of electrodes includes a tissue penetrating electrode that is implantable through the endocardium of the right atrium and the central fibrous body from the Koch triangle region of the right atrium for delivering cardiac therapy to the left ventricle or sensing electrical activity of the left ventricle in a basal region and / or a septal region of the left ventricular myocardium of a patient's heart. The plurality of electrodes further includes a right atrial electrode that is positionable within the right atrium for delivering cardiac therapy to the right atrium of a patient's heart or sensing electrical activity of the right atrium of a patient's heart. The implantable medical device further includes: a therapy delivery circuit operably coupled to the plurality of electrodes for delivering cardiac therapy to a patient's heart; and a sensing circuit operably coupled to the plurality of electrodes for sensing electrical activity of a patient's heart. The implantable medical device further includes a controller that includes processing circuitry operably coupled to the therapy delivery circuit and the sensing circuit. The controller is configured to perform at least one of the following: deliver antitachycardia pacing therapy using the plurality of electrodes, and deliver shock therapy using a separate medical device.

[0251] In illustrative embodiment 50, a method includes delivering at least one of antitachycardia pacing therapy and shock therapy using a separate medical device at least using a tissue penetrating electrode that is implantable through the endocardium of the right atrium and the central fibrous body from the Koch triangle region of the right atrium for delivering cardiac therapy to the left ventricle or sensing electrical activity of the left ventricle in a basal region and / or a septal region of the left ventricular myocardium of a patient's heart.

[0252] In illustrative embodiment 51, the device or method of any one of illustrative embodiments 49 - 59 is included, wherein the controller is further configured to, or the method further includes: detecting whether a ventricular rhythm exceeds a selected ventricular rhythm threshold after initiating delivery of antitachycardia pacing therapy.

[0253] In illustrative embodiment 52, the device or method of any one of illustrative embodiments 49 - 51 is included, wherein the controller is further configured to, or the method further includes: monitoring for tachycardia in response to detecting a regular ventricular rhythm.

[0254] In illustrative embodiment 53, the device or method of any one of illustrative embodiments 49 - 52 is included, wherein the controller is further configured to, or the method further includes: delivering shock therapy using a separate device in response to detecting a ventricular rhythm that exceeds a selected ventricular rhythm threshold.

[0255] In illustrative embodiment 54, a device or method of any one of illustrative embodiments 49 - 53 is included, wherein the shock therapy includes delivering signaling pulses to the left ventricle using a tissue penetrating electrode.

[0256] In illustrative embodiment 55, a device or method of illustrative embodiment 54 is included, wherein the signaling pulses are configured to be detected by a separate medical device to trigger delivery of a shock from the separate medical device to cardiac tissue.

[0257] In illustrative embodiment 56, a device or method of any one of illustrative embodiments 49 - 54 is included, wherein the separate medical device is not connected to the implantable medical device by a metallic conductor.

[0258] Accordingly, various embodiments of VFA cardiac therapy are disclosed. Although reference is made herein to the accompanying sets of drawings that form a part of this disclosure, those of ordinary skill in the art will understand that various adaptations and modifications of the embodiments described herein are within the scope of this disclosure or do not depart from the scope of this disclosure. For example, various aspects of the embodiments described herein can be combined in various ways. Accordingly, it is to be understood that within the scope of the appended claims, the claimed invention may be practiced otherwise than as specifically described herein.

[0259] It will be understood that each block of the block diagrams and combinations of these blocks can be implemented by means for performing the functions shown.

[0260] All references and publications cited herein are hereby expressly incorporated by reference in their entirety, except to the extent that they may directly conflict with this disclosure.

[0261] Unless otherwise specified, 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 commonly used herein and are not intended to limit the scope of this disclosure.

[0262] Unless otherwise indicated, all numbers expressing feature sizes, amounts, and physical properties used in the specification and claims should be understood to be modified by the term "exactly" or "about". Accordingly, unless indicated to the contrary, the numerical parameters set forth in the foregoing specification and attached claims are approximations that may vary depending upon the desired properties sought by those of ordinary skill in the art utilizing the teachings disclosed herein or, for example, within the ordinary range of experimental error.

[0263] References to numerical ranges by endpoints include all numbers within that range (e.g., from 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, and 5) and any range within that range. As used herein, the term "up to" or "not greater than" a number (e.g., up to 50) includes that number (e.g., 50), and the term "not less than" a number (e.g., not less than 5) includes that number (e.g., 5).

[0264] The terms "coupled" or "connected" mean that elements are attached to each other either directly (in direct contact with each other) or indirectly (with one or more elements therebetween attaching the two elements). Either term may be modified by "operatively" or "operably" (the two words being used interchangeably) to describe a coupling or connection configured to allow components to interact to perform at least some function (e.g., an intracardiac medical device may be operatively or operably coupled to an extracorporeal ICD to initiate shock therapy).

[0265] References to "one embodiment", "an embodiment", "certain embodiments", or "some embodiments", etc. mean that the particular features, configurations, components, or characteristics described in connection with that embodiment are included in at least one embodiment of the present disclosure. Thus, the appearances of such phrases in various places throughout this specification are not necessarily all referring to the same embodiment. Additionally, the particular features, configurations, components, or characteristics may be combined in any suitable manner in one or more embodiments.

[0266] The words "preferred" and "preferably" mean that embodiments of the present disclosure may provide certain benefits in certain circumstances. However, in the same or other circumstances, other embodiments may also be preferred. Further, the listing of one or more preferred embodiments does not imply that other embodiments are not useful and is not intended to exclude other embodiments from the scope of the present disclosure.

[0267] As used in this specification and the appended claims, the singular forms "a", "an", and "the" include embodiments having plural referents, unless the context clearly dictates otherwise. As used in this specification and the appended claims, the term "or" is generally employed in its sense including "and / or", unless the context clearly dictates otherwise.

[0268] As used herein, terms such as "have / having", "include / including", and "comprise / comprising" are used in their open sense and generally mean "including but not limited to". It will be understood that "consisting essentially of", "consisting of", etc. are subsumed within "comprising", etc.

[0269] The term "and / or" means one or all of the listed elements or a combination of at least two of the listed elements.

[0270] A list accompanied by the phrases "at least one of...", "including at least one of...", and "one or more of..." refers to any one of the items in the list and any combination of two or more items in the list.

Claims

1. An implantable medical device, comprising: A plurality of electrodes, the plurality of electrodes comprising: A tissue piercing electrode that can be implanted through the right atrial endocardium and the central fibrous body from the Koch triangle area of the right atrium for delivering cardiac therapy to the left ventricle or sensing the electrical activity of the left ventricle in the basal region and / or septal region of the left ventricular myocardium of the patient's heart; and A right atrial electrode that can be positioned within the right atrium for delivering cardiac therapy to the right atrium of the patient's heart or sensing the electrical activity of the right atrium of the patient's heart; A therapy delivery circuit operably coupled to the plurality of electrodes for delivering cardiac therapy to the patient's heart; A sensing circuit operably coupled to the plurality of electrodes for sensing the electrical activity of the patient's heart; and A controller, the controller comprising processing circuitry operably coupled to the therapy delivery circuit and the sensing circuit, the controller being configured to: Monitor the electrical activity of the right atrium using the right atrial electrode; Monitor the electrical activity of the left ventricle using the tissue piercing electrode, the tissue piercing electrode being implanted through the right atrial endocardium and the central fibrous body from the Koch triangle area of the right atrium in the basal region and / or septal region of the left ventricular myocardium of the patient's heart to sense the electrical activity of the left ventricle in the basal region and / or septal region of the left ventricular myocardium; and Deliver tachycardia therapy based on the monitored electrical activity of the right atrium and left ventricle.

2. A method, comprising: Monitoring the electrical activity of the right atrium of the patient's heart using a right atrial electrode; Monitoring the electrical activity of the left ventricle of the patient's heart using a tissue piercing electrode, the tissue piercing electrode being implanted through the right atrial endocardium and the central fibrous body from the Koch triangle area of the right atrium in the basal region and / or septal region of the left ventricular myocardium of the patient's heart to sense the electrical activity of the left ventricle in the basal region and / or septal region of the left ventricular myocardium; And Delivering tachycardia therapy based on the monitored electrical activity of the right atrium and left ventricle.

3. The device according to claim 1 or the method according to claim 2, wherein The controller is configured to perform, or the method further comprises: Delivering tachycardia therapy based on the monitored electrical activity of the right atrium and left ventricle includes at least one of the following: Delivering antitachycardia pacing therapy using the plurality of electrodes, and delivering shock therapy using a separate medical device.

4. The device or method according to any one of the preceding claims, wherein, The controller is further configured to perform, or the method further comprises: Suppressing tachycardia therapy in response to determining that the cardiac rhythm of the patient's heart has 1:1 atrioventricular conduction.

5. The apparatus according to any one of claims 1 and 3 - 4, further comprising a housing extending from a proximal end region to a distal end region, wherein, The right atrial electrode is coupled to the housing without a lead, and the tissue piercing electrode is coupled to the distal end region of the housing without a lead, wherein the therapy delivery circuit, the sensing circuit, and the controller are enclosed within the housing.

6. An implantable medical device, comprising: A plurality of electrodes, the plurality of electrodes comprising: A tissue puncture electrode that can be implanted through the endocardium of the right atrium and the central fibrous body from the Koch triangle region of the right atrium for delivering cardiac therapy to the left ventricle or sensing electrical activity of the left ventricle in the basal region and / or septal region of the left ventricular myocardium of a patient's heart; and A right atrial electrode that can be positioned within the right atrium for delivering cardiac therapy to the right atrium of the patient's heart or sensing electrical activity of the right atrium of the patient's heart; A therapy delivery circuit operably coupled to the plurality of electrodes for delivering cardiac therapy to the patient's heart; A sensing circuit operably coupled to the plurality of electrodes for sensing electrical activity of the patient's heart; and A controller including processing circuitry operably coupled to the therapy delivery circuit and the sensing circuit, the controller being configured to: Monitor electrical activity of the right atrium using the right atrial electrode; and Monitor electrical activity of the left ventricle using the tissue puncture electrode implanted in the basal region and / or septal region of the left ventricular myocardium of the patient's heart through the endocardium of the right atrium and the central fibrous body from the Koch triangle region of the right atrium to sense electrical activity of the left ventricle; and Determine tachycardia of the patient's heart based on the monitored electrical activity of the right atrium and left ventricle.

7. A method comprising: Monitoring electrical activity of the right atrium of a patient's heart using a right ventricular electrode; Monitoring electrical activity of the left ventricle of the patient's heart using a tissue puncture electrode implanted in the basal region and / or septal region of the left ventricular myocardium of the patient's heart through the endocardium of the right atrium and the central fibrous body from the Koch triangle region of the right atrium to sense electrical activity of the left ventricle; And Determining tachycardia of the patient's heart based on the monitored electrical activity of the right atrium and left ventricle.

8. The device according to claim 6 or the method according to claim 7, wherein The controller is further configured to perform, or the method further comprises: determining whether the cardiac rhythm of the patient's heart has 1:1 atrioventricular conduction.

9. The device or method according to claim 8, wherein The controller is further configured to perform, or the method further comprises: determining an appropriate tachycardia treatment in response to the cardiac rhythm not having 1:1 atrioventricular conduction based on the monitored electrical activity of the right atrium and left ventricle.

10. The apparatus or method according to any one of the preceding claims, wherein, Determining tachycardia of the patient's heart based on the monitored electrical activity of the right atrium and left ventricle includes: determining that the atrial rhythm is regular and determining that the ventricular rhythm exceeds a selected ventricular rhythm threshold.

11. An implantable medical device comprising: A plurality of electrodes, the plurality of electrodes comprising: A tissue puncture electrode that can be implanted through the endocardium of the right atrium and the central fibrous body from the Koch triangle region of the right atrium for delivering cardiac therapy to the left ventricle or sensing at least one of the electrical activity of the left ventricle in the basal region and / or septal region of the left ventricular myocardium of a patient's heart; and A right atrial electrode that can be positioned within the right atrium for delivering cardiac therapy to the right atrium of the patient's heart and / or sensing the electrical activity of the right atrium of the patient's heart. A therapy delivery circuit operably coupled to the plurality of electrodes for delivering cardiac therapy to the patient's heart; A sensing circuit operably coupled to the plurality of electrodes for sensing the electrical activity of the patient's heart; A controller including a processing circuitry operably coupled to the therapy delivery circuit and the sensing circuit, the controller being configured to: Perform at least one of the following monitoring: monitoring the electrical activity of the right atrium using the right atrial electrode, and monitoring the electrical activity of the left ventricle using the tissue piercing electrode implanted in the basal region and / or septal region of the left ventricular myocardium of the patient's heart through the Koch triangle region of the right atrium, through the right atrial endocardium and the central fibrous body; and Deliver cardiac resynchronization pacing based on the monitored electrical activity using at least the tissue piercing electrode implanted in the basal region and / or septal region of the left ventricular myocardium of the patient's heart through the Koch triangle region of the right atrium, through the right atrial endocardium and the central fibrous body for pacing one or both ventricles.

12. A method comprising: Performing at least one of the following monitoring: monitoring the electrical activity of the right atrium of the patient's heart using a right atrial electrode, and monitoring the electrical activity of the left ventricle using a tissue piercing electrode implanted in the basal region and / or septal region of the left ventricular myocardium of the patient's heart through the Koch triangle region of the right atrium, through the right atrial endocardium and the central fibrous body; And Delivering cardiac resynchronization pacing based on the monitored electrical activity using at least the tissue piercing electrode implanted in the basal region and / or septal region of the left ventricular myocardium of the patient's heart through the Koch triangle region of the right atrium, through the right atrial endocardium and the central fibrous body, including pacing one or both ventricles.

13. The device according to claim 11 or the method according to claim 12, wherein, The controller is further configured to, or the method further comprises: monitoring the far-field electrical activity of the right ventricle using the right atrial electrode.

14. An implantable medical device comprising: A housing extending from a proximal end region to a distal end region; A plurality of electrodes including: A tissue piercing electrode non-lead coupled to the distal end region of the housing and capable of being implanted through the Koch triangle region of the right atrium, through the right atrial endocardium and the central fibrous body for delivering cardiac therapy to the left ventricle and / or sensing the electrical activity of the left ventricle in the basal region and / or septal region of the left ventricular myocardium of the patient's heart; and A right atrial electrode non-lead coupled to the housing and capable of being positioned within the right atrium for delivering cardiac therapy to the right atrium of the patient's heart and / or sensing the electrical activity of the right atrium of the patient's heart; A therapy delivery circuit within the housing operably coupled to the plurality of electrodes for delivering cardiac therapy to the patient's heart; A sensing circuit within the housing, the sensing circuit being operably coupled to the plurality of electrodes for sensing electrical activity of the patient's heart; and A controller, the controller including processing circuitry operably coupled within the housing to the therapy delivery circuit and the sensing circuit, the controller being configured to: Perform at least one of the following monitoring: monitor electrical activity of the right atrium using the right atrium electrode, and monitor electrical activity of the left ventricle using the tissue piercing electrode that passes through the endocardium of the right atrium and the central fibrous body from the Koch triangle region of the right atrium and into the basal region and / or septal region of the left ventricular myocardium of the patient's heart; and Deliver cardiac resynchronization pacing based on the monitored electrical activity using at least the tissue piercing electrode that passes through the endocardium of the right atrium and the central fibrous body from the Koch triangle region of the right atrium and is implanted in the basal region and / or septal region of the left ventricular myocardium of the patient's heart to pace one or both ventricles.

15. An implantable medical device, comprising: A plurality of electrodes, the plurality of electrodes including: A tissue piercing electrode that can be implanted from the Koch triangle region of the right atrium through the endocardium of the right atrium and the central fibrous body for at least one of delivering cardiac therapy to the left ventricle and sensing electrical activity of the left ventricle in the basal region and / or septal region of the left ventricular myocardium of the patient's heart; and A right atrium motion detector that can be positioned within the right atrium for sensing mechanical activity of the right atrium of the patient's heart; A therapy delivery circuit operably coupled to the plurality of electrodes for delivering cardiac therapy to the patient's heart; A sensing circuit operably coupled to the plurality of electrodes for sensing electrical activity of the patient's heart; and A controller, the controller including processing circuitry operably coupled to the therapy delivery circuit and the sensing circuit, the controller being configured to: Monitor mechanical activity of the right atrium using the right atrium motion detector; and Deliver cardiac resynchronization pacing based on the monitored mechanical activity of the right atrium using at least the tissue piercing electrode that passes through the endocardium of the right atrium and the central fibrous body from the Koch triangle region of the right atrium and is implanted in the basal region and / or septal region of the left ventricular myocardium of the patient's heart to pace one or both ventricles.

Images