SINGLE CHANNEL SENSING USING VfA DEVICES

Abstract

Atrial-to-ventricular (VfA) devices, systems, and methods may be configured to use a right atrial electrode positionable within a right atrium to sense electrical activity within the right atrium and a basal region implantable from a Koch triangle region within the right atrium through a right atrial endocardium and a central fibrous body to a left ventricular myocardium of a patient's heart, one or both of a tissue piercing electrode in one or more of a spacer region and a base-spacer region to sense electrical activity in one or more of the base region, the spacer region and the base-spacer region of the left ventricular myocardium obtains single channel cardiac electrical activity. Various processes, windowing, and threshold processes may be used to identify atrial and ventricular events within the single channel cardiac electrical activity.

Description

[0001] This application claims the benefit of U.S. patent application serial number 17 / 824,764, filed on May 25, 2022, which is incorporated herein by reference in its entirety.

[0002] The disclosure herein relates to single channel sensing using atrium-to-ventricle (VfA) devices, systems and methods.

[0003] The cardiac conduction system includes the sinoatrial (SA) node, the atrioventricular (AV) node, the His bundle, bundle branches, and Purkinje fibers. The heartbeat is initiated in the SA node, which can be described as the natural "pacemaker" of the heart. The electrical impulses generated 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 appropriate AV synchronization. The electrical impulses are conducted from the AV node to the ventricular myocardium via the His bundle, bundle branches, and Purkinje fibers.

[0004] Patients with conduction system abnormalities (such as AV node poor conduction 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 pacemakers, implantable cardioverter-defibrillators (ICDs), or cardiac resynchronization therapy (CRT) devices provide therapeutic electrical stimulation to the patient's heart via electrodes on one or more implanted endocardial, epicardial, or coronary venous leads positioned in the heart or positioned adjacent to 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 intrinsic depolarization of the heart and control the delivery of therapeutic stimulation to the heart based on the sensing.

[0005] Delivering therapeutic electrical stimulation to the heart can be used to address cardiac conditions that may occur in patients, such as ventricular dyssynchrony. Ventricular dyssynchrony can be described as a lack of synchronization or differences in contraction timing in the different chambers of the heart. Significant differences in contraction timing can reduce cardiac efficiency. CRT delivered to the heart by an IMD can enhance cardiac output by resynchronizing the electromechanical activity of the heart's ventricles. Because CRT delivers pacing to the right atrium, right ventricle, and left ventricle, CRT is sometimes referred to as "three-chamber pacing."

[0006] Arrhythmias can be treated by, for example, using an IMD or ICD to deliver an electric shock therapy for cardioversion or defibrillation of the heart, each of which can sense the patient's heart rhythm and classify the heart rhythm according to an arrhythmia detection scheme to detect the onset of tachycardia or fibrillation. The detected arrhythmias may include ventricular tachycardia (VT), rapid ventricular tachycardia (FVT), ventricular fibrillation (VF), atrial tachycardia (AT) and atrial fibrillation (AF). Anti-tachycardia pacing (ATP) is a painless therapy that can be used to treat ventricular tachycardia (VT) to essentially terminate many monomorphic rapid rhythms. Although ATP is painless, ATP may not provide effective treatment for all types of VT and supraventricular tachycardia (SVT). For example, ATP may be ineffective for polymorphic VT with variable morphology. Polymorphic VT and ventricular fibrillation (VF) may be more fatal and may require rapid treatment by electric shock.

[0007] Dual-chamber medical devices are available that include a transvenous atrial lead carrying electrodes that can be placed in the right atrium and a transvenous ventricular lead carrying electrodes that can be placed in the right ventricle via the right atrium. The dual-chamber medical device itself is typically implanted in a subcutaneous pocket, and the transvenous lead is tunneled to the subcutaneous pocket. The dual-chamber medical device can sense both atrial and ventricular electrical signals, and can provide both atrial pacing and ventricular pacing as needed to promote normal heart rhythm and AV synchronization. Some dual-chamber medical devices can treat atrial arrhythmias and ventricular arrhythmias.

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

[0009] In some patients, a single chamber device may adequately meet the patient's needs. However, a single chamber device capable of only single chamber sensing and therapy may not fully address cardiac conduction disease or abnormalities in all patients (e.g., those with some forms of AV dyssynchrony or tachycardia). In addition to ICD functionality in some cases, dual chamber sensing and / or pacing functionality may be used to restore a more normal heart rhythm. Summary of the invention

[0010] Exemplary atrium-to-ventricle (VfA) devices, systems, and methods may be described as providing single-channel sensing of atrial and ventricular events (e.g., contraction, depolarization, etc.). The VfA device may include multiple electrodes, and typically includes at least: a right atrial electrode (e.g., in contact with myocardial tissue of the right atrium, in a right atrial blood pool, etc.) for sensing at least electrical activity of the right atrium (e.g., from myocardial tissue, from a blood pool, etc.); and a tissue-piercing ventricular electrode, which is configured to be located in the myocardial tissue of the left ventricle to at least sense the electrical activity of the myocardial tissue of the left ventricle. Furthermore, in one or more alternative configurations, the tissue-piercing electrode may be configured to be located in the myocardial tissue of the right ventricle to at least sense the electrical activity of the myocardial tissue of the right ventricle. Additionally, the VfA device typically includes a right atrial blood pool electrode, which is positioned or configured to be positioned in the blood pool of the right atrium. A single sensing channel may be formed or defined using two or more of a right atrial electrode, a tissue-piercing ventricular electrode, and a right atrial blood pool electrode to sense cardiac electrical activity. Depending on the electrodes used to form or define the single sensing channel, various processes further described herein may be used to identify, discriminate, or determine atrial and ventricular events. Using a single channel, as opposed to multiple channels, may improve efficiency and may reduce the complexity of exemplary VfA devices, systems, and methods.

[0011] An exemplary implantable medical device may include, among other things: a plurality of electrodes; a therapy delivery circuit operatively coupled to the one or more electrodes to deliver cardiac therapy to a patient's heart; a sensing circuit operatively coupled to the one or more electrodes to sense electrical activity of the patient's heart; and a controller including a processing circuit system operatively coupled to the therapy delivery circuit and the sensing circuit. The plurality of electrodes may include: a right atrial electrode positionable within the right atrium of the patient's heart (e.g., in contact with myocardial tissue of the right atrium, within a right atrial blood pool, etc.); and a tissue piercing electrode implantable through the right atrium from the triangle of Koch region of the right atrium through the right atrial endocardium and the central fiber body, and positionable to contact one or more of a basal region, a septal region, and a basal-septal region of the left ventricular myocardium of the patient's heart. The controller may be configured to: sense single-channel electrical activity using one or both of the right atrial electrode positionable in the right atrium to sense electrical activity in the right atrium and the tissue-piercing electrode implantable from the Koch triangle area in the right atrium through the right atrial endocardium and the central fiber body into one or more of the basal region, the septal region, and the basal-septal region of the left ventricular myocardium of the patient's heart to sense electrical activity in one or more of the basal region, the septal region, and the basal-septal region of the left ventricular myocardium; and identify atrial events and ventricular events based on the monitored electrical activity.

[0012] An exemplary method may include: obtaining single-channel electrical activity using one or both of a right atrial electrode positioned within the right atrium (e.g., in contact with myocardial tissue of the right atrium, within a right atrial blood pool, etc.) to sense electrical activity within the right atrium and a tissue-piercing electrode implanted from the Koch triangle area within the right atrium through the right atrial endocardium and central fiber body into one or more of the basal region, the septal region, and the basal-septal region of the left ventricular myocardium of the patient's heart to sense electrical activity in one or more of the basal region, the septal region, and the basal-septal region of the left ventricular myocardium; and identifying atrial events and ventricular events based on the obtained electrical activity.

[0013] An exemplary implantable medical device may include: a housing that is fully implantable in the right atrium of a patient's heart; a plurality of electrodes that are leadless and fixed to the housing; and a controller that includes a processing circuit system that is operably coupled to the electrodes and within the housing. The plurality of electrodes may include: a right atrial electrode that is positionable within the right atrium (e.g., in contact with myocardial tissue within the right atrium, within a right atrial blood pool, etc.); and a tissue piercing electrode that is implantable through the right atrium of the patient so as to extend toward the left ventricular myocardium of the patient's heart. The controller may be configured to: monitor single-channel electrical activity using one or both of the right atrial electrode that is positionable within the right atrium and the tissue piercing electrode that is implantable through the right atrium of the patient so as to extend toward the left ventricular myocardium of the patient's heart; and identify atrial events and ventricular events based on the monitored electrical activity.

[0014] An exemplary method may include: utilizing a fully intracardiac leadless device to obtain single-channel electrical activity using a right atrial electrode of the leadless device positioned within the right atrium of the patient's heart and a tissue-piercing electrode of the leadless device extending toward the left ventricular myocardium of the patient's heart; and identifying atrial events and ventricular events based on the obtained electrical activity.

[0015] The above summary is not intended to describe each embodiment or every implementation of the present disclosure. A more complete understanding will become apparent and appreciated by referring to the following detailed description and claims in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 is a conceptual diagram of an illustrative cardiac therapy system that includes a VfA device implanted in a patient's heart and a separate medical device positioned outside the patient's heart.

[0017] Figure 2 is located relative to the anatomy of the patient's heart Figure 1 An enlarged conceptual diagram of the VfA device.

[0018] Figure 3 is a conceptual illustration of a patient's heart in a standard 17-segment view of the left ventricle showing various electrode implantation locations for use with the exemplary systems, devices, and methods described herein.

[0019] Figure 4 Is a distal fixation and electrode assembly Figure 1 A perspective view of a VfA device, the distal fixation and electrode assembly including a distal housing-based electrode implemented as a ring electrode.

[0020] Figure 5 is a perspective view of another exemplary VfA device.

[0021] Figure 6 It can be enclosed in, for example Figure 1 to Figure 2 and Figures 4 to 5 A block diagram of the exemplary circuitry within the housing of a VfA device to provide their functions and therapies.

[0022] Figure 7 For example, Figure 1 to Figure 2 and Figures 4 to 6 Block diagram of an exemplary method of single-channel sensing performed by an exemplary system and apparatus.

[0023] Figure 8 For example, Figure 1 to Figure 2 and Figures 4 to 6 Block diagram of another exemplary method of single-channel sensing performed by an exemplary system and apparatus.

[0024] 9A to 9E is a graph of single-channel electrical activity measured using the right atrial electrode and the right atrial blood pool electrode of an exemplary VfA device, showing Figure 7 method.

[0025] FIG. 10A to FIG. 10B is a graph of single-channel electrical activity measured using tissue-piercing electrodes and right atrial blood pool electrodes of an exemplary VfA device, showing Figure 8 method.

[0026] FIG. 11A to FIG. 11B is a graph of single-channel electrical activity measured using tissue-piercing electrodes and right atrial electrodes of an exemplary VfA device, showing Figure 8 method.

[0027] Fig.12 For example, Figure 1 to Figure 2 and Figures 4 to 6 Block diagram of another exemplary method of single-channel sensing performed by an exemplary system and apparatus. DETAILED DESCRIPTION

[0028] In the following detailed description of exemplary embodiments, reference is made to the accompanying drawings, which form a part of the embodiments, and in which are shown by way of illustration specific embodiments that can be practiced. It should be understood that other embodiments can be utilized and the structural scope can be changed without departing from (e.g., still falling within) the scope of the present disclosure hereby presented.

[0029] Reference Figures 1 to 12Describe exemplary devices, systems and methods. It will be apparent to those skilled in the art that an element or process from one embodiment may be used in combination with an element or process of other embodiments, and the possible embodiments of such devices, systems and methods using the feature combinations set forth herein are not limited to the specific embodiments shown in the figures and / or described herein. Further, it will be appreciated that the embodiments described herein may include many elements that are not necessarily shown to scale. Further, it will be appreciated that the timing of the processes herein and the size and shape of the individual elements may be modified but still fall within the scope of the present disclosure, but some timing, one or more shapes and / or sizes or element types may be superior to other timing, one or more shapes and / or sizes or element types.

[0030] The present disclosure describes implantable pacing devices, particularly VfA implantable pacing devices, that are configured to sense atrial and ventricular events utilizing a single sensing channel that can be used to provide one or more different pacing therapies, such as, for example, AV synchronized pacing therapy, cardiac resynchronization therapy, anti-tachycardia pacing therapy, defibrillation, cardioversion, etc. The implantable device can be paired with another device, such as, for example, an extravascular implantable cardioverter-defibrillator (EV-ICD), to provide cardioversion and defibrillation.

[0031] As will be further described herein, some embodiments of an exemplary VfA implantable medical device (IMD) can be described as a dual-chamber leadless pacemaker implanted in the Koch's triangle (TOK) region of the right atrium. In one embodiment, the VfAIMD may include three electrodes: a tissue-piercing ventricular electrode positioned in the left ventricular myocardium; a right atrial electrode contacting the atrial myocardial tissue at the TOK; and a right atrial blood pool electrode. Generally speaking, one or both of the tissue-piercing ventricular electrode and the right atrial electrode can be used as a cathode, and the right atrial blood pool electrode can be used as an anode for sensing and pacing.

[0032] Typically, a dual-chamber pacing IMD may utilize two independent sensing channels, with one sensing electrode pair located in the right atrium for sensing atrial signals and another sensing electrode pair located proximal to the ventricle (e.g., within the ventricle) for sensing ventricular signals. In the two independent sensing channel configuration, far-field signals (i.e., signals originating from outside the cavity where the sensing electrodes (and more specifically, the cathode of the sensing electrode pair) are placed) are minimized by common-mode rejection of closely spaced bipolar (e.g., sensing electrode pairs) and relatively large distances of the atrial and ventricular electrodes, respectively, from far-field signal sources.

[0033] Due to the proximity of the electrodes to tissue that provides far-field signals, such as, for example, the right atrial tip electrode to ventricular tissue, the right atrial blood pool electrode (e.g., the common anode ring in the right atrium) to ventricular tissue, and the tissue piercing left ventricular electrode to atrial tissue, the VfA-IMD may sense more or have larger far-field signals than a conventional dual-chamber pacing IMD. As a result, atrial signals sensed using the VfA IMD may be contaminated by far-field R waves, and ventricular signals sensed using the VfA IMD may be contaminated by far-field P waves. When the sensed atrial signals are analyzed for atrial events, far-field R waves may be undesirable, and similarly, when the sensed ventricular signals are analyzed for ventricular events, far-field P waves may be undesirable. In addition, it may be desirable for the VfA IMD to have or limit a maximum shelf life (e.g., battery life) while also having a minimum battery or power source.

[0034] The exemplary VfA devices, systems, and methods described herein may utilize a single sensing channel to identify atrial events and ventricular events to facilitate cardiac condition diagnosis and cardiac pacing therapy. The exemplary VfA devices, systems, and methods may be described as minimizing current consumption associated with sensing, which may maximize battery life and shelf life of the VfA device, minimize hardware design complexity and space usage (e.g., if a single channel is used instead of two channels, one less sensing amplifier and one less amplifier may be used), maximize the duration of electrogram episodes that may be stored in a constrained or restricted memory pool, and minimize current consumption associated with telemetry when a single sensing channel is linked up instead of two sensing channels. Thus, the exemplary devices, systems, and methods described herein may provide a single sensing channel that may be used to determine one or more cardiac conditions and deliver or configure various cardiac therapies.

[0035] As described herein, the present disclosure relates to implantable medical devices, systems, and methods for atrium-to-ventricle (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 reference is made herein to implantable medical devices, particularly VfA IMDs, these methods and processes may be used with any medical device or system associated with or used to treat a patient's heart. Various other applications will become apparent to those skilled in the art having the benefit of this disclosure.

[0036] The present disclosure also provides, among other things, an IMD including a tissue-piercing left ventricular electrode and a right atrial electrode. The tissue-piercing left ventricular electrode can be implanted in the base, septum and / or base-septum region of the left ventricular myocardium of the patient's heart from the Koch triangle region of the right atrium through the right atrial endocardium and the central fibrous body. In a leadless IMD, the tissue-piercing electrode can extend leadlessly from the distal end region of the housing of the device, and the right atrial electrode can be coupled to the housing (e.g., a portion of the housing or positioned on the outside of the housing) leadlessly. In a leaded IMD, one or more of the electrodes can be coupled to the housing using an implantable lead. When the device is implanted, the electrode can be used to sense electrical activity in one or more atria and / or ventricles of the patient's heart. The electrode can be used to deliver cardiac therapy, such as single-chamber pacing for atrial fibrillation, atrioventricular synchronous pacing for bradycardia, asynchronous pacing, triggered pacing, cardiac resynchronization pacing for ventricular asynchrony, anti-tachycardia pacing or shock therapy. When used in conjunction with an extravascular or subcutaneous ICD, the exemplary IMD may be in operative communication with the extravascular or subcutaneous ICD to trigger or initiate a shock delivered by the IMD.

[0037] It should be understood that the processes and methods described herein can be implemented by one or more different devices (e.g., implantable medical devices) and systems. Such devices and systems can include electronic circuits, power supplies, sensors, electrodes, fluid delivery devices, etc. Figure 1 An exemplary cardiac therapy system 2 is depicted in the drawings, which includes an implantable medical device (IMD) 10 that can be used to implement the methods and processes described herein. Although it should be understood that the present disclosure can utilize one or both of leadless implantable medical devices and leaded implantable medical devices, the exemplary cardiac therapy system 2 includes a leadless IMD 10 implanted in a patient's heart 8.

[0038] IMD 10 can be used at least to treat cardiac conditions by delivering electrical stimulation to one or more areas or zones of heart 8. For example, IMD 10 can deliver pacing pulses to one or more chambers of the heart, such as the right atrium and the left ventricle. In addition, for example, IMD 10 can deliver anti-tachycardia pacing pulses to one or more chambers of the heart, such as the right atrium and the left ventricle. In addition, for example, IMD 10 can deliver cardioversion or defibrillation shock pulses to one or more parts of the heart. And still further, for example, IMD 10 can deliver pacing pulses to one or more parts of the cardiac conduction system, such as the left bundle branch. In some embodiments, device 10 can be configured for single-chamber pacing, and can, for example, switch between single-chamber pacing and multi-chamber pacing (e.g., dual-chamber or triple-chamber pacing).

[0039] A device 10 is shown implanted in a target implant region 4 of the right atrium (RA) of a patient's heart 8. The device 10 may include one or more fixation members 20 that anchor the distal end of the device 10 against the atrial endocardium in the target implant region 4 within the Koch's triangle. The device 10 may include one or more fixation members 20 that anchor the distal end of the device against the atrial endocardium in the target implant region 4. The target implant region 4 may be located between the bundle of His 5 (or bundle of His) and the coronary sinus 3, and may be adjacent to the tricuspid valve 6. The device 10 may be described as an atrium-to-ventricle (VfA) device that may sense electrical activity or provide therapy to one or both ventricles (e.g., the right ventricle, the left ventricle, or both ventricles) while being typically disposed in the right atrium. Specifically, the device 10 may include a tissue-piercing electrode that may be implanted from the Koch's triangle region of the right atrium through the right atrial endocardium and the central fiber body in the basal, septal, and / or basal-septal regions of the left ventricular myocardium of the patient's heart.

[0040] The device 10 can be described as a leadless implantable medical device. As used herein, "leadless" refers to a device without leads extending from the patient's heart 8. Further, although the leadless device can have leads, the leads do not extend from the outside of the patient's heart to the inside of the patient's heart or from the inside of the patient's heart to the outside of the patient's heart. Some leadless devices can be introduced through a vein, but once implanted, the device does not or may not include any transvenous leads and can be configured to provide cardiac therapy without the use of any transvenous leads. Further, when the housing of the device is positioned in the atrium, specifically, the leadless device does not use leads to be operably connected to one or more electrodes. In addition, the leadless electrodes can be coupled to the housing of the medical device without the use of leads between the electrodes and the housing.

[0041] The device 10 can be configured to monitor one or more physiological parameters of the patient (e.g., electrical activity of the patient's heart, chemical activity of the patient's heart, hemodynamic activity of the patient's heart, and motion and acceleration of one or more parts of the patient's heart). The monitored physiological parameters can then be used by the IMD to detect various cardiac conditions, such as ventricular tachycardia (VT), ventricular fibrillation (VF), supraventricular tachycardia (SVT), atrial fibrillation (AF), atrial tachycardia (AT), myocardial ischemia / infarction, etc., and treat these cardiac conditions through therapy. Such therapy may include delivering anti-tachycardia pacing (ATP) therapy, defibrillation or cardioversion shock therapy (e.g., delivering high-energy shock pulses), cardiac resynchronization therapy, AV synchronized pacing therapy, bradycardia pacing, etc. Specifically, IMD 10 may monitor atrial and ventricular electrical activity to determine or identify atrial and ventricular events (eg, contractions, depolarizations, etc.), determine one or more cardiac conditions (eg, tachyarrhythmias), and deliver therapy to the patient, such as AV synchronized pacing therapy or CRT.

[0042] The device 10 may also include a dart electrode assembly 12 that defines or has a straight shaft extending from a distal end region of the device 10. The dart electrode assembly 12 may be primarily used to provide ventricular pacing and sensing, and may be placed or at least configured to be placed through the atrial myocardium and the central fiber body and into the ventricular myocardium 14 or along the ventricular septum without completely penetrating the ventricular endocardial or epicardial surface. The dart electrode assembly 12 may carry or include an electrode at the distal end region of the shaft so that the electrode may be positioned within the ventricular myocardium for sensing ventricular signals and delivering ventricular pacing pulses (e.g., depolarizing the left and / or right ventricles to cause contraction of the left and / or right ventricles). In some examples, the electrode at the distal end region of the shaft is a cathode electrode provided for use in a bipolar electrode pair for pacing and sensing. Although implantation region 4 as shown may enable one or more electrodes of dart electrode assembly 12 to be positioned within the ventricular myocardium, it will be appreciated that devices having aspects disclosed herein may be implanted in other locations, as appropriate, for multi-chamber pacing (e.g., dual-chamber or triple-chamber pacing), single-chamber pacing with multi-chamber sensing, single-chamber pacing and / or sensing, or other clinical therapies and applications.

[0043] It should be understood that although the device 10 is described herein as including a single dart electrode assembly, the device 10 may include more than one dart electrode assembly that is placed or configured to be placed through the atrial myocardium and the central fiber body and into the ventricular myocardium 14 or along the ventricular septum without completely passing through the ventricular endocardial or epicardial surface. In addition, each dart electrode assembly may carry or include more than a single electrode at the distal end region of the shaft or at other regions along the shaft (e.g., the proximal region or the central region). In other words, each dart electrode assembly may include one or more electrodes located at the distal end region of the shaft, which may be used, for example, for bipolar sensing, bipolar pacing, or additional sensing for pacing capture.

[0044] The cardiac therapy system 2 may also include a separate medical device 50 (in Figure 1 ), the separate medical device may be positioned outside the patient's heart 8 (e.g., subcutaneously) and may be capable of being operably coupled to the patient's heart 8 to deliver cardiac therapy thereto. In one example, the separate medical device 50 may be an extravascular ICD. In some embodiments, the extravascular ICD may include a defibrillation lead that includes or carries a defibrillation electrode. A therapy carrier may be present between the defibrillation electrode on the defibrillation lead and the housing electrode of the ICD. Further, one or more electrodes of the ICD may also be used to sense electrical signals associated with the patient's heart 8. The ICD may be configured to deliver shock therapy including one or more defibrillation or cardioversion shocks. For example, if a rapid arrhythmia is sensed, the ICD may send pulses via electrical leads to shock the heart and restore its normal rhythm. In some examples, the ICD can deliver shock therapy without placing electrical leads in the heart or attaching wires directly to the heart (subcutaneous ICD). An example of an extravascular subcutaneous ICD that may be used with the system 2 described herein may be described in U.S. Patent No. 9,278,229, issued on March 8, 2016, which is incorporated herein by reference in its entirety.

[0045] In the case of electric shock therapy (e.g., a defibrillation shock provided by a defibrillation electrode of a defibrillation lead), a separate medical device 50 (e.g., an extravascular ICD) can include a control circuit that uses a therapy delivery circuit to generate a defibrillation shock having any of a variety of waveform characteristics (including leading edge voltage, slope, delivered energy, pulse phase, etc.). The therapy delivery circuit can, for example, generate a monophasic, biphasic, or multiphasic waveform. In addition, the therapy delivery circuit can generate a defibrillation waveform with different amounts of energy. For example, the therapy delivery circuit can generate a defibrillation waveform that delivers a total of approximately 60 joules (J) to 80 J of energy for subcutaneous defibrillation.

[0046] The individual medical device 50 may also include a sensing circuit. The sensing circuit may be configured to obtain an electrical signal sensed by one or more combinations of electrodes, and process the obtained signal. The components of the sensing circuit may include analog components, digital components, or a combination thereof. The sensing circuit may, for example, include one or more readout amplifiers, filters, rectifiers, threshold detectors, analog-to-digital converters (ADCs), etc. The sensing circuit may convert the sensed signal into a digital form, and provide the digital signal to a control circuit for processing and / or analysis. For example, the sensing circuit may amplify the signal from the sensing electrode, and convert the amplified signal into a multi-bit digital signal by an ADC, and then provide the digital signal to the control circuit. In one or more embodiments, the sensing circuit may also compare the processed signal with a threshold value to detect the presence of atrial or ventricular depolarization (e.g., P wave or R wave) and indicate the presence of atrial depolarization (e.g., P wave) or ventricular depolarization (e.g., R wave) to the control circuit.

[0047] The device 10 and the separate medical device 50 can cooperate to provide cardiac therapy to the patient's heart 8. For example, the device 10 and the separate medical device 50 can be used to detect tachyarrhythmias, monitor tachyarrhythmias, and / or provide tachyarrhythmia-related therapy. For example, the device 10 can wirelessly communicate with the separate medical device 50 to trigger an electric shock therapy using the separate medical device 50. As used herein, "wireless" refers to an operational coupling or connection between the device 10 and the separate medical device 50 without the use of metal conductors. In one example, wireless communication can use a unique, signal-conducting, or triggered electrical pulse provided by the device 10 that is conducted through the patient's tissue and can be detected by the separate medical device 50. In another example, wireless communication can use a communication interface (e.g., an antenna) of the device 10 to provide electromagnetic radiation that propagates through the patient's tissue and can be detected, for example, using a communication interface (e.g., an antenna) of the separate medical device 50.

[0048] Figure 2 yes Figure 1 1 and an enlarged conceptual diagram of the anatomical structure of the IMD 10 and the patient's heart 8. As described herein, the IMD 10 is generally configured to sense electrical activity and / or deliver pacing therapy. The IMD device 10 may include a housing 30 that defines the internal components of the device 10 (such as the combination of Figure 6The housing 30 may include a hermetically sealed interior cavity in which the sensing circuitry, therapy delivery circuitry, control circuitry, memory, telemetry circuitry, other optional sensors, and power supplies (generally described) reside. The housing 30 may include (e.g., be formed of, or be formed from) an electrically conductive material such as, for example, 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 include (e.g., be formed of, or be formed from) a non-conductive material including ceramic, glass, sapphire, silicone, polyurethane, epoxy, acetyl copolymer plastic, polyetheretherketone (PEEK), a liquid crystal polymer, or other biocompatible polymer.

[0049] In at least one embodiment, the housing 30 can be described as extending between the distal end region 32 and the proximal end region 34 and as defining a generally cylindrical shape, for example to facilitate catheter delivery. In other embodiments, the housing 30 can be prismatic or any other shape to perform the functions and utilities described herein. The housing 30 can include, for example, a delivery tool interface member 26 defined or positioned at the proximal end region 34 for engaging with a delivery tool during implantation of the device 10.

[0050] All or a portion of the housing 30 may serve as a sensing and / or pacing electrode during cardiac therapy. In the example shown, the housing 30 includes a proximal housing-based electrode 24 that circumscribes a proximal portion of the housing 30 (e.g., closer to the proximal end region 34 than the distal end region 32). When the housing 30 is a conductive material (such as a titanium alloy or other examples listed above) (e.g., defines a conductive material, is formed thereof, etc.), portions of the housing 30 may be electrically insulated by a coating of a non-conductive material (such as parylene, polyurethane, silicone, epoxy resin, or other biocompatible polymer), thereby exposing one or more discrete areas of the conductive material to form or define the proximal housing-based electrode 24. When the housing 30 is a conductive material (such as a ceramic, glass, or polymer material) (e.g., defines a non-conductive material, is formed thereof, etc.), a conductive coating or layer (such as titanium, platinum, stainless steel, or alloys thereof) may be applied to one or more discrete areas of the housing 30 to form or define the proximal housing-based electrode 24. In other examples, the proximal housing-based electrode 24 may be a component mounted or assembled to the housing 30, such as a ring electrode. The proximal housing-based electrode 24 may be electrically coupled to the internal circuit system 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.

[0051] In the example shown, the proximal shell-based electrode 24 is located closer to the shell proximal end region 34 than to the shell distal end region 32, and thus may be referred to as the proximal shell-based electrode 24. However, in other examples, the proximal shell-based electrode 24 may be located at other locations along the shell 30, for example, farther away from the location shown.

[0052] At the distal end region 32, the IMD 10 may include a distal fixation and electrode assembly 36, which may include one or more fixation members 20 and one or more dart electrode assemblies 12 of equal or unequal lengths. In one such example as shown, a single dart electrode assembly 12 includes a shaft 40 extending distally away from the housing distal end region 32, and one or more electrode elements, such as a tip electrode 42, at or near a free distal end region of the shaft 40. The tip electrode 42 may have a conical or hemispherical distal tip with a relatively narrow tip diameter (e.g., less than about 1 millimeter (mm)) for penetrating and passing through tissue layers without the use of a sharp tip or a needle tip with a sharp or beveled edge.

[0053] The dart electrode assembly 12 can be configured to pierce one or more tissue layers to position the tip electrode 42 within a desired tissue layer (e.g., ventricular myocardium). Thus, the height or length 47 of the shaft 40 can correspond to the expected pacing site depth, and the shaft 40 can have a relatively high compressive strength along its longitudinal axis to resist bending in a lateral or radial direction when pressed toward and into the implantation area 4. If a second dart electrode assembly 12 is employed, its length may not be equal to the expected pacing site depth and may be configured to act as an indifferent electrode for delivering pacing energy to the tissue and / or sensing signals from the tissue. In one embodiment, a longitudinal axial force can be applied to the tip electrode 42, for example, by applying a longitudinal thrust to the proximal end region 34 of the housing 30, to advance the dart electrode assembly 12 into tissue within the target implantation area. In at least one embodiment, the height 47 or length of the shaft 40 can be adjusted relative to the housing 10 (e.g., it can be adjusted during implantation to deliver stimulation at an appropriate depth).

[0054] The shaft 40 can be described as being longitudinally non-compressible and / or elastically deformable in the transverse or radial direction when subjected to a transverse or radial force to allow temporary bending, for example, as tissue moves, but can return to its normal straight position when the transverse force is reduced. Therefore, the dart electrode assembly 12 including the shaft 40 can be described as being elastic. When the shaft 40 is not exposed to any external forces or is only exposed to forces along its longitudinal center axis, the shaft 40 can maintain a straight linear position as shown.

[0055] In other words, the shaft 40 of the dart electrode assembly 12 can normally be a straight member and can be rigid. In other embodiments, the shaft 40 can be described as being relatively rigid, but still having limited flexibility in the lateral direction. Further, the shaft 40 can be non-rigid to allow some lateral bending to occur with heart movement. However, in a relaxed state, when not subjected to any external forces, the shaft 40 can maintain a straight position as shown to space the tip electrode 42 from the housing distal end region 32 by at least the height or length 47 of the shaft 40.

[0056] The one or more fixing members 20 can be described as having one or more "pointed teeth" in a normal curved position. The pointed teeth can be maintained in a distally extended position within the delivery tool. The distal tips of the pointed teeth can penetrate the heart tissue to a limited depth before elastically or resiliently bending proximally back to the normal curved position (as shown) when released from the delivery tool. Further, the fixing member 20 may include, for example, one or more aspects described in U.S. Patent No. 9,675,579 issued on June 13, 2017 and U.S. Patent No. 9,119,959 issued on September 1, 2015, each of which is incorporated herein by reference in its entirety.

[0057] The distal fixation and electrode assembly 36 includes the distal shell-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 a cathode electrode paired with the proximal shell-based electrode 24 or the distal shell-based electrode 22 acting as a return anode electrode. Specifically, the tip electrode 42 can be used in a single sensing channel or carrier, including one of the proximal shell-based electrode 24 and the distal shell-based electrode 22. As described herein, a single sensing channel can be used to identify or determine atrial events (e.g., atrial depolarization, atrial contraction, P waves, etc.) and ventricular events (e.g., ventricular depolarization, ventricular contraction, R waves, etc.). The identified atrial and ventricular events can be used to control atrial pacing pulses (e.g., delivered in the absence of a sensed P wave) using the distal shell-based electrode 22 as a cathode and the proximal shell-based electrode 24 as a return anode, and to control atrial synchronized ventricular pacing pulses delivered using the tissue-piercing tip electrode 42 as a cathode and either the proximal shell-based electrode 24 or the distal shell-based electrode 22 as a return anode.

[0058] As shown in this illustration, in some pacing applications, the target implantation area 4 is along the atrial endocardium 18, typically below the AV node 15 and the bundle of His 5. The dart electrode assembly 12 can at least partially define a height or length 47 of the shaft 40 to pass through the atrial endocardium 18 in the target implantation area 4, through the central fiber body 16, and into the ventricular muscle 14 without penetrating the ventricular endocardial surface 17. When the height or length 47 of the dart electrode assembly 12 is fully advanced into the target implantation area 4, the tip electrode 42 can be placed within the ventricular muscle 14, and the distal housing-based electrode 22 can be positioned in close contact or close proximity to the atrial endocardium 18. In various examples, the dart electrode assembly 12 can have a total combined height or length 47 (the total combined height or length includes the tip electrode 42 and the shaft 40) of about 3 mm to about 8 mm. 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.

[0059] IMD 10 may include an acoustic and / or motion detector 11 within housing 30. Acoustic or motion detector 11 may be operably coupled to one or more of control circuitry 80, sensing circuitry 86, or therapy delivery circuitry 84, as described with respect to Figure 6 As described. The acoustic and / or motion detector 11 can be used to monitor mechanical activity, such as atrial mechanical activity (e.g., atrial contraction) and / or ventricular mechanical activity (e.g., ventricular contraction). In some embodiments, the acoustic and / or motion detector 11 can be used to detect right atrial mechanical activity. Non-limiting examples of the acoustic and / or motion detector 11 include one or both of an accelerometer and a microphone. In some embodiments, the mechanical activity detected by the acoustic and / or motion detector 11 can be used to supplement or replace the electrical activity detected by one or more of the electrodes of the device 10. For example, the acoustic and / or motion detector 11 can be used in addition to or as an alternative to the proximal shell-based electrode 24.

[0060] The acoustic and / or motion detector 11 may also be used for rate responsive detection or to provide rate responsive IMD. Various techniques related to rate responsiveness may be described in U.S. Pat. No. 5,154,170 issued on Oct. 13, 1992 and U.S. Pat. No. 5,562,711 issued on Oct. 8, 1996, each of which is incorporated herein by reference in its entirety.

[0061] In various embodiments, the acoustic and / or motion detector 11 can be used as a heart sound (HS) sensor and can be implemented as a microphone and / or a 1-axis, 2-axis, or 3-axis accelerometer. In one embodiment, the acoustic and / or motion sensor 11 is implemented as a piezoelectric crystal mounted within the housing 30 that responds to mechanical motion associated with heart sounds. Examples of other embodiments of acoustic sensors that may be suitable for implementation with the technology of the present disclosure can be generally described in U.S. Patent Nos. 4,546,777, 6,869,404, 5,554,177, and 7,035,684, each of which is incorporated herein by reference in its entirety.

[0062] In other words, various types of acoustic and / or motion sensors 11 may be used. For example, the acoustic and / or motion sensor 11 may be described as any implantable or external sensor that is responsive to one or more of the heart sounds and thereby is capable of producing or generating an analog electrical signal that is related in time and amplitude to the heart sounds. The analog signal may then be processed by the HS sensing module (which may include digital conversion) to obtain HS parameters such as amplitude or relative time intervals derived by the HS sensing module or control circuit 80. The acoustic and / or motion sensor 11 and the HS sensing module may be incorporated into an IMD (e.g., device 10) capable of delivering CRT or another cardiac therapy being optimized, or may be implemented in a separate device that communicates wired or wirelessly with another IMD or in an external programmer or computer used during a pacing parameter optimization procedure as described herein.

[0063] Figure 3 1 is a two-dimensional (2D) ventricle diagram 100 (e.g., a top-down view) of a patient's heart, showing a left ventricle 120 and a right ventricle 122 in a standard 17-segment view. Diagram 100 defines or includes a plurality of zones 126 corresponding to different regions of a human heart. As shown, zones 126 are numbered 1 to 17 (e.g., corresponding to a standard 17-segment human heart model, corresponding to the 17 segments of the left ventricle of a human heart). Zones 126 of diagram 100 may include basal anterior zone 1, basal anterior septal zone 2, basal infraseptal zone 3, basal infraseptal zone 4, basal infralateral zone 5, basal anterior lateral zone 6, mid-anterior zone 7, mid-anterior septal zone 8, mid-inferior septal zone 9, mid-inferior zone 10, mid-inferior lateral zone 11, mid-anterior lateral zone 12, apical anterior zone 13, apical septal zone 14, apical infraseptal zone 15, apical lateral zone 16, and apex zone 17. The infraseptal and anteroseptal regions of the right ventricle 122 are also shown, as well as the right bundle branch (RBB) 25 and the left bundle branch (LBB) 27 .

[0064] In some embodiments, any of the tissue-piercing electrodes of the present disclosure may be implanted in the basal, septal, and / or basal-septal regions of the left ventricular myocardium of the patient's heart. Specifically, the tissue-piercing electrode may be implanted from the Koch triangle region of the right atrium through the right atrial endocardium and the central fiber body. Once implanted, the tissue-piercing electrode may be positioned in a target implantation region 4(e) such as the basal region, septal region, or basal-septal region of the left ventricular myocardium. Figure 1 to Figure 2 ). Referring to FIG. 100, the base region includes one or more of the base front region 1, the base front septal region 2, the base lower septal region 3, the base lower region 4, the middle front region 7, the middle front septal region 8, the middle lower septal region 9, and the middle lower region 10. Referring to FIG. 100, the septal region includes one or more of the base front septal region 2, the base front septal region 3, the middle front septal region 8, the middle lower septal region 9, and the top septal region 14. The base-septal region may include one or more of the base front septal region 2, the base lower septal region 3, the middle front septal region 8, and the middle lower septal region 9.

[0065] In some embodiments, when implanted, the tissue-piercing electrode can be positioned in the superior inferior / posterior basal septal region of the left ventricular myocardium. The superior inferior / posterior basal septal region of the left ventricular myocardium may include a portion of one or more of the inferior basal septal region 3 and the inferior middle septal region 9 (e.g., only the inferior basal septal region, only the inferior middle septal region, or both the inferior basal septal region and the inferior middle septal region). For example, the superior inferior / posterior basal septal region may include an area 124 generally illustrated as a dashed line boundary. As shown, the dashed line boundary indicates the approximate location of the superior inferior / posterior basal septal region, which may vary slightly in shape or size depending on the specific application.

[0066] Figure 43D perspective view of a device 10 capable of delivering pacing therapy and / or delivering sensed cardiac signals. As shown, a distal fixation and electrode assembly 36 includes a distal housing-based electrode 22 implemented as a ring electrode. When the fixing member tines 20a, 20b, and 20c of the fixing member 20 engage with the atrial tissue, the distal housing-based electrode 22 can be positioned in close contact or operatively close 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, when the device 10 is pushed out of the delivery tool, the tines 20a, 20b, and 20c can pierce the atrial endocardial surface, and when the tines are no longer constrained in the delivery tool, they bend back to their normal curved position (as shown). When the tines 20a, 20b, and 20c bend back to their normal position, the fixing member 20 can pull the distal fixing member and electrode assembly 36 toward the atrial endocardial surface. When the distal fixation member and electrode assembly 36 is "pulled" toward the atrial endocardium, the tip electrode 42 can be advanced through the atrial muscle and central fiber body and into the ventricular muscle. The distal housing-based electrode 22 can then be positioned against or adjacent to the atrial endocardial surface.

[0067] The distal shell-based electrode 22 may include a ring formed of a conductive material such as titanium, platinum, iridium, or alloys thereof. The distal shell-based electrode 22 may be a single continuous ring electrode. In other examples, portions of the ring may be coated with an electrically insulating coating, such as polyparaxylene, polyurethane, silicone, epoxy, or another insulating coating, to reduce the conductive surface area of ​​the ring 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 shell-based electrode 22. Reducing the conductive surface area of ​​the distal shell-based electrode 22, such as by covering portions of the conductive ring with an insulating coating, may increase the electrical impedance of the distal shell-based electrode 22, and thereby reduce the current delivered during pacing of pulses to capture myocardium (e.g., atrial muscle tissue). Lower current consumption may save a power source of the device 10, such as one or more rechargeable or non-rechargeable batteries.

[0068] As described above, the distal shell-based electrode 22 can be configured as an atrial cathode electrode for delivering pacing pulses to atrial tissue at the implant site in combination with the proximal shell-based electrode 24 as a return anode. Additionally, the distal shell-based electrode 22 can be used in a single sensing channel or carrier, including the proximal shell-based electrode 24 and one of the tissue-piercing electrodes 42. As described herein, a single sensing channel can be used to identify or determine atrial events (e.g., atrial depolarization, atrial contraction, P waves, etc.) and ventricular events (e.g., ventricular depolarization, ventricular contraction, R waves, etc.). The identified atrial events and ventricular events can be used to control atrial pacing pulses (e.g., delivered without sensing a P wave) using the distal shell-based electrode 22 as a cathode and the proximal shell-based electrode 24 as a return anode, and to control atrial synchronized ventricular pacing pulses delivered using the tissue-piercing tip electrode 42 as a cathode and the proximal shell-based electrode 24 or the distal shell-based electrode 22 as a return anode.

[0069] Figure 5 3 is a three-dimensional perspective view of another leadless implantable medical device 310 that can be configured to treat a cardiac condition by delivering pacing therapy for single-chamber or multi-chamber heart therapy (e.g., dual-chamber or triple-chamber heart therapy). The device 310 may include a housing 330 having an outer sidewall 335 extending from a housing distal end region 332 to a housing proximal end region 334, shown as a cylindrical outer sidewall. The housing 330 can enclose an electronic circuit system configured to perform single-chamber or multi-chamber heart therapy, including atrial and ventricular cardiac electrical signal sensing and pacing of atrial and ventricular chambers. A delivery tool interface member 326 is shown on the housing proximal region 334.

[0070] The distal fixation and electrode assembly 336 can be coupled to the housing distal end region 332. The distal fixation and electrode assembly 336 can include an electrically insulating distal member 372 coupled to the housing distal end region 332. The tissue-piercing electrode assembly 312 can extend away from the housing distal end region 332, and the plurality of non-tissue-piercing electrodes 322 can be directly coupled to the insulating distal member 372. As shown, the tissue-piercing electrode assembly 312 extends in a longitudinal direction away from the housing distal end region 332 and can be coaxial with the longitudinal center axis 331 of the housing 330.

[0071] The distal tissue piercing electrode assembly 312 may include an electrically insulating shaft 340 and a tip electrode 342 (e.g., a tissue piercing electrode). As described herein, embodiments may include a plurality of electrodes positioned along the insulating shaft 340. In some examples, the tissue piercing electrode assembly 312 may be described as comprising a helical shaft 340 and a movable fixation member of a distal cathode tip electrode 342. The helical shaft 340 may extend from a shaft distal end region 343 to a shaft proximal region 341, which may be directly coupled to an insulating distal member 372. The helical shaft 340 may be coated with an electrically insulating material, such as parylene or other examples listed herein, to avoid sensing or stimulating cardiac tissue along the length of the shaft.

[0072] As described herein, the tip electrode 342 is located or positioned at the distal end region 343 of the shaft and can act as a cathode electrode for delivering ventricular pacing pulses and sensing ventricular electrical signals using the proximal shell-based electrode 324 or one or more of the non-tissue piercing electrodes 322 as a return anode when the tip electrode 342 is advanced close to or into the ventricular tissue. The proximal shell-based electrode 324 can be an annular electrode of the outer shell 330 and can be defined by an uninsulated portion of the longitudinal sidewall 335. Other portions of the shell 330 that do not act as electrodes can be used in conjunction with the above. Figure 4 The device 10 is coated with an electrically insulating material similar to that described.

[0073] Two or more tissue-piercing electrodes (e.g., any type of tissue-piercing electrodes) that penetrate into the LV myocardium may be used for more localized pacing capture and to mitigate ventricular pacing spikes, thereby affecting capture of atrial tissue. In some embodiments, the plurality of tissue-piercing electrodes may include two or more dart-type electrode assemblies (e.g., Figure 4 Non-limiting examples of multiple tissue piercing electrodes include two dart electrode assemblies, a spiral electrode with a dart electrode assembly extending therethrough (e.g., through the center), or a double-wound spiral. Multiple tissue piercing electrodes can also be used for bipolar or multipolar pacing.

[0074] In some embodiments, the one or more tissue piercing electrodes (e.g., any type of tissue piercing electrode) that penetrate into the LV myocardium can be multipolar tissue piercing electrodes. The multipolar tissue piercing electrodes can include one or more electroactive elements and electrical separation elements that can enable bipolar or multipolar pacing from the one or more tissue piercing electrodes. In other words, each tissue piercing electrode can include one or more individual electrodes or electroactive segments or regions that are independent of each other.

[0075] A plurality of non-tissue piercing electrodes 322 may be provided along the periphery of the insulating distal member 372, which is located at the periphery of the tissue piercing electrode assembly 312. The insulating distal member 372 may define a distally facing surface 338 of the device 310 and a circumferential surface 339 of the device 310 adjacent to the longitudinal sidewall 335 of the housing. The non-tissue piercing electrodes 322 may be formed of a conductive material such as titanium, platinum, iridium, or alloys thereof. In the illustrated embodiment, six non-tissue piercing electrodes 322 are radially spaced at equal distances along the periphery of the insulating distal member 372, however, two or more non-tissue piercing electrodes 322 may be provided.

[0076] The non-tissue piercing electrodes 322 can be discrete components that are each held within a corresponding recess in the insulating member 372 that is sized and shaped to match the non-tissue piercing electrodes 322. In other examples, the non-tissue piercing electrodes 322 can each be an uninsulated exposed portion of a single-piece member mounted within or on the insulating distal member 372. The middle portion of the single-piece member that does not serve as an electrode can be insulated by the insulating distal member 372, or if the middle portion is exposed to the surrounding environment, it can be coated with an electrically insulating coating, such as parylene, polyurethane, silicone, epoxy, or other insulating coating.

[0077] When tissue-piercing electrode assembly 312 is advanced into cardiac tissue, at least one non-tissue-piercing electrode 322 may be positioned against, in close contact with, or operatively proximate to the surface of cardiac tissue to deliver pulses and / or sense cardiac electrical signals generated by the patient's heart. For example, when tissue-piercing electrode assembly 312 is advanced into atrial tissue and through the central fiber body until distal tip electrode 342 is positioned in direct contact with ventricular tissue (e.g., ventricular myocardium and / or portions of the ventricular cardiac conduction system), non-tissue-piercing electrode 322 may be positioned in contact with right atrial endocardial tissue for pacing and sensing in the atrium.

[0078] The non-tissue piercing electrode 322 may be coupled to therapy delivery circuitry and sensing circuitry as will be described herein with reference to Figure 6As described, the therapy delivery circuit and the sensing circuit are enclosed by the housing 330. When delivering conventional pacing therapy, when used in combination with one of the proximal housing-based electrode 324 and the tip electrode 342 as a return anode, the non-tissue piercing electrode 322 can be used together as a cathode electrode for delivering atrial pacing pulses and for sensing single-channel electrical activity. The switch circuit system included in the sensing circuit can be activated under the control of the control circuit to connect one or more of the non-tissue piercing electrodes to a single sensing channel. The distal non-tissue piercing electrodes 322 can be electrically isolated from each other, so that each individual electrode of the electrodes 322 can be individually selected by the switch circuit system included in the therapy delivery circuit to act as an atrial cathode electrode individually or in combination of two or more electrodes of the electrodes 322. The switch circuit system included in the therapy delivery circuit can be activated under the control of the control circuit to couple one or more of the non-tissue piercing electrodes 322 to the atrial pacing circuit. Two or more of the non-tissue piercing electrodes can be selected at one time to serve as multiple atrial cathode electrodes.

[0079] Certain non-tissue piercing electrodes 322 may be selected for atrial pacing and / or atrial sensing based on atrial capture threshold testing, electrode impedance, P-wave signal strength in the cardiac electrical signal, or other factors. For example, a single non-tissue piercing electrode 322 or any combination of two or more separate non-tissue piercing electrodes may be selected to serve as a cathode electrode that provides an optimal combination of low pacing capture threshold amplitude and relatively high electrode impedance to achieve reliable atrial pacing using minimal current draw from a power source.

[0080] In some cases, when the tissue-piercing electrode assembly 312 anchors the housing 330 at the implantation site 4, the distal-facing surface 338 can uniformly contact the atrial endocardial surface. In this case, all of the electrodes 322 can be selected together to form an atrial cathode or anode. Alternatively, every other electrode in the electrodes 322 can be selected together to form a multi-point atrial cathode with a higher electrical impedance, which is still evenly distributed along the distal-facing surface 338. Alternatively, a subset of one or more electrodes 322 along one side of the insulating distal member 372 can be selected to provide pacing at a desired location that achieves the lowest pacing capture threshold due to the relative position of the electrodes 322 to the atrial tissue being paced.

[0081] In other cases, depending on the positioning and orientation of the tissue piercing electrode assembly 312 into the heart tissue, the distally facing surface 338 can be oriented at an angle relative to the adjacent endocardial surface. In this case, one or more of the non-tissue piercing electrodes 322 can be positioned to be in closer contact with the adjacent endocardial tissue than other non-tissue piercing electrodes 322, which can be angled away from the endocardial surface. By providing multiple non-tissue piercing electrodes along the periphery of the insulating distal member 372, the angle of the tissue piercing electrode assembly 312 and the housing distal end region 332 relative to the heart surface (e.g., the right atrial endocardial surface) may not necessarily be substantially parallel. Anatomical differences and positioning differences can cause the distally facing surface 338 to be angled or tilted relative to the endocardial surface, however, the multiple non-tissue piercing electrodes 322 distributed along the periphery of the insulating distal member 372 increase the possibility of good contact between one or more electrodes 322 and adjacent heart tissue, thereby using at least a subset of the multiple electrodes 322 to promote acceptable pacing thresholds and reliable cardiac event sensing. Contact or fixation circumferentially along the entire circumference of the insulating distal member 372 may not be required.

[0082] The non-tissue piercing electrode 322 can be described as including a first portion 322a extending along a distally facing surface 338 and a second portion 322b extending along a circumferential surface 339. The first portion 322a and the second portion 322b can be continuous exposed surfaces, so that the active electrode surface is wrapped around the peripheral edge 376 of the insulating distal member 372, which joins the distally facing surface 338 and the circumferential surface 339. The non-tissue piercing electrode 322 can include one or more of the electrodes 322 along the distally facing surface 338, one or more electrodes along the circumferential surface 339, one or more electrodes extending along both the distally facing surface 338 and the circumferential surface 339, or any combination thereof. The exposed surface of each of the non-tissue piercing electrodes 322 can be flush with the corresponding distally facing surface 338 and / or circumferential surface. In other examples, each of the non-tissue piercing electrodes 322 can have a convex surface protruding from the insulating distal member 372. However, any raised surface of electrode 322 may define a smooth or rounded non-tissue-piercing surface.

[0083] The distal fixation and electrode assembly 336 can seal the distal end region of the housing 330 and can provide a basis for mounting the electrode 322 thereon. The electrode 322 can be referred to as a housing-based electrode. The electrode 322 can be carried by no shaft or other extension that extends an active electrode portion (such as a distal tip electrode 342 located at the distal tip of the helical shaft 340 extending away from the housing 330) away from the housing 330. Other examples of non-tissue-piercing electrodes coupled to the distal-facing surface and / or circumferential surface of the insulative distal member presented herein include those described herein with respect to Figure 4 The distal shell-based electrode 22 described in the device 10, as described herein with respect to Figure 4 The device 10 described herein may include distal shell-based electrodes, button electrodes, other shell-based electrodes, and other circumferential ring electrodes extending circumferentially around the assembly 36. Any non-tissue piercing electrodes located peripherally of the central tissue piercing electrode directly coupled to the distal insulating member may be provided to function individually, collectively, or in any combination as cathode electrodes for delivering pacing pulses to adjacent cardiac tissue. When ring electrodes, such as the distal shell-based electrode 22 and / or circumferential ring electrodes, are provided, portions of the ring electrodes may be electrically insulated by a coating to provide a plurality of distributed non-tissue piercing electrodes along the distal-facing surface and / or circumferential surface of the insulating distal member.

[0084] Compared with the tissue piercing electrodes provided along the distal fixation and electrode assembly 336, the non-tissue piercing electrodes 322 and other examples listed above are expected to provide more reliable and effective atrial pacing and sensing. Compared with the ventricular cavity wall, the atrial cavity wall is relatively thin. The tissue piercing atrial cathode electrode may extend too deep into the atrial tissue, resulting in unintentional continuous or intermittent capture of the ventricular tissue. Due to the ventricular signal with a larger signal strength in the cardiac electrical signal received by the tissue piercing atrial cathode electrode that is physically closer to the ventricular tissue, the tissue piercing atrial cathode electrode may cause interference with the sensed atrial signal. The tissue piercing electrode assembly 312 can be firmly anchored in the ventricular tissue to stabilize the implantation position of the device 310 and provide reasonable certainty that the tip electrode 342 performs sensing and pacing in the ventricular tissue, while the non-tissue piercing electrode 322 can provide electrical stimulation to the atrial tissue and sense / monitor the electrical activity of the atrial tissue. The length of tissue-piercing electrode assembly 312 from distal-facing surface 338 can be in the range of about 4 mm to about 8 mm to reach left ventricular tissue. In some cases, device 310 can achieve four-chamber pacing by delivering atrial pacing pulses from therapy delivery circuit 84 via non-tissue-piercing electrode 322 in target implant region 4 to achieve bi-atrial (right and left atrium) capture, and by delivering ventricular pacing pulses from ventricular pacing circuit via tip electrode 342 advanced from target implant region 4 into ventricular tissue to achieve bi-ventricular (right and left ventricle) capture.

[0085] Figure 6 is a block diagram of a circuit system that may be enclosed within housing 30, 330 of device 10, 310 to provide the following functions: sensing cardiac signals, determining tachyarrhythmias, detecting tachyarrhythmias, distinguishing tachyarrhythmias, determining supraventricular tachycardias, detecting supraventricular tachycardias, distinguishing supraventricular tachycardias, determining capture of atrial and ventricular myocardial tissue, determining capture of one or more portions of the cardiac conduction system, and / or delivering pacing therapy to one or both of the myocardial tissue and the cardiac conduction system. Figure 1The individual medical devices 50 shown may include some or all of the same components that may be configured in a similar manner. The electronic circuit system enclosed within the housing 30, 330 may include software, firmware, and hardware that cooperatively monitor atrial and ventricular electrical heart signals, determine tachyarrhythmias, detect tachyarrhythmias, distinguish tachyarrhythmias, determine supraventricular tachycardias, detect supraventricular tachycardias, distinguish supraventricular tachycardias, determine whether cardiac conduction system capture has occurred, determine when cardiac therapy (such as ATP, defibrillation, and cardioversion) can be delivered or inhibited, and deliver electrical pulses to the patient's heart according to programmed therapy modes and pulse control parameters. The electronic circuit system may include a control circuit 80 (e.g., including a processing circuit system), a memory 82, a therapy delivery circuit 84, a sensing circuit 86, and / or a telemetry circuit 88. In some embodiments, the device 10, 310 includes one or more sensors 90 for generating signals associated with one or more physiological functions, states, or conditions of the patient. For example, one or more sensors 90 may include a patient activity sensor for determining the need for pacing therapy and / or controlling the pacing rate. Further, for example, one or more sensors 90 may include an inertial measurement unit (e.g., an accelerometer) for measuring movement. Further, for example, one or more sensors 90 may include an acoustic sensor to monitor heart sounds. Still further, for example, one or more sensors 90 may include a patient activity sensor, which may include an accelerometer. An increase in the patient's metabolic demand due to increased activity as indicated by the patient activity sensor can be determined using the patient activity sensor. In other words, the device 10, 310 may include other sensors 90 for sensing signals from the patient to determine whether to deliver and / or control the electrical stimulation therapy delivered by the therapy delivery circuit 84.

[0086] The power supply 98 can provide power as needed to the circuitry of the device 10, 310 including each of the components 80, 82, 84, 86, 88, 90. The power supply 98 can include one or more energy storage devices, such as one or more rechargeable or non-rechargeable batteries. The connection between the power supply 98 and each of the components 80, 82, 84, 86, 88, 90 can be understood from the overall block diagram presented to a person of ordinary skill in the art (not shown). For example, the power supply 98 can be coupled to one or more charging circuits included in the therapy delivery circuit 84 to provide power for charging a holding capacitor included in the therapy delivery circuit 84, which is discharged at an appropriate time under the control of the control circuit 80 for delivering pacing pulses and / or shock pulses. The power supply 98 can also be coupled to components of the sensing circuit 86 (such as a sense amplifier, an analog-to-digital converter, a switching circuit system, etc.), the sensor 90, the telemetry circuit 88, and the memory 82 to provide power to various circuits.

[0087] The functional blocks shown represent the functions included in the device 10, 310, and may include any discrete and / or integrated electronic circuit components that implement analog and / or digital circuits that are capable of producing the functions attributed to the medical device 10, 310 described herein. The various components may include processing circuit systems (such as application specific integrated circuits (ASICs), electronic circuits, processors (shared, dedicated or group) and memory) that execute one or more software or firmware programs, combinational logic circuits, state machines, or other suitable components or combinations of components that provide the described functions. The specific form of software, hardware and / or firmware used to implement the functions disclosed herein will be determined primarily by the specific system architecture employed in the medical device and the specific detection and therapy delivery methods employed by the medical device.

[0088] The memory 82 may include any volatile, nonvolatile, magnetic, or electrically non-transitory computer-readable storage medium, such as random access memory (RAM), read-only memory (ROM), nonvolatile RAM (NVRAM), electrically erasable programmable ROM (EEPROM), flash memory, or any other memory device. In addition, the memory 82 may include a non-transitory computer-readable medium storing instructions that, when executed by one or more processing circuits, cause the control circuit 80 and / or other processing circuit systems to perform the following operations: monitor atrial and ventricular electrical activity; detect tachyarrhythmias; determine tachyarrhythmias; distinguish tachyarrhythmias; detect supraventricular tachycardias; determine supraventricular tachycardias; distinguish supraventricular tachycardias; determine whether atrial electrical activity is reliable; determine ventricular events (e.g., ventricular contractions); determine atrial events (e.g., atrial contractions); compare the QRS morphology to a template indicative of normal sinus rhythm (e.g., a template of the QRS morphology of cardiac electrical activity during normal sinus rhythm); analyze one or more motion signals to determine acceleration of the atria and ventricles; and / or perform single-chamber, dual-chamber, or triple-chamber calibrated pacing therapy (e.g., single-chamber or multi-chamber pacing) or other cardiac therapy functions attributed to the device 10, 310 (e.g., sensing or delivery therapy). Non-transitory computer-readable media storing instructions may include any of the media listed above.

[0089] The control circuit 80 may communicate, for example, via a data bus, with the therapy delivery circuit 84 and the sensing circuit 86 to sense cardiac electrical signals and control the delivery of cardiac electrical stimulation therapy in response to sensed cardiac activity (e.g., sensed atrial and ventricular events, such as P waves / atrial depolarization and P waves / ventricular depolarization, or their absence). The tip electrode 42, 342, the distal shell-based electrode 22, 322, and the proximal shell-based electrode 24, 324 may be electrically coupled to the therapy delivery circuit 84 for delivering electrical stimulation pulses to the sensing circuit 86 and for sensing electrical signals.

[0090] The distal shell-based electrodes 22, 322 and the proximal shell-based electrodes 24, 324 can be coupled to the sensing circuit 86 to sense atrial signals, such as the P wave accompanying the depolarization of the atrial muscle. In examples including two or more selectable distal shell-based electrodes, the sensing circuit 86 may include a switch circuit system for selectively coupling one or more available distal shell-based electrodes to the event detection circuit system. The switch circuit system may include a switch array, a switch matrix, a multiplexer, or any other type of switch device suitable for selectively coupling components of the sensing circuit 86 to selected electrodes. The tip electrode 42, 324 and the proximal shell-based electrodes 24, 324 can be coupled to the sensing circuit 86 for sensing ventricular signals, such as the R wave accompanying the depolarization of the ventricular myocardium.

[0091] As described herein, the sensing circuit 86 may include an event detection circuit system for detecting cardiac depolarization activity (e.g., P waves, QRS complex waves, R waves, etc.). The event detection circuit system may be configured to amplify, filter, digitize, and rectify the electrical signals received from the selected electrodes to improve the signal quality for cardiac electrical events. The event detection circuit system may include one or more sense amplifiers, filters, rectifiers, threshold detectors, comparators, analog-to-digital converters (ADCs), timers, or other analog or digital components. Event sensing thresholds (such as, for example, P wave sensing thresholds, R wave sensing thresholds, etc.) may be automatically adjusted under the control of the control circuit 80, for example, based on a timing period and sensing threshold 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.

[0092] Upon detecting a cardiac electrical event based on a sensing threshold crossing, the sensing circuit 86 may generate a sensed event signal that is transmitted to the control circuit 80. For example, the sensing circuit 86 may generate a P-wave sensed event signal in response to a P-wave sensing threshold crossing, and generate an R-wave sensed event signal in response to an R-wave sensing threshold crossing. The control circuit 80 may use the sensed event signal to set a pacing escape interval timer that controls a base time interval for scheduling cardiac pacing pulses. The sensed event signal may trigger or inhibit pacing pulses, depending on the particular programmed pacing mode. For example, a P-wave sensed event signal received from the sensing circuit 86 may 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 AV pacing interval expires, the ventricular pacing pulse may be inhibited. If the AV pacing interval expires before control circuit 80 receives an R-wave sense event signal from sensing circuit 86, control circuit 80 may use therapy delivery circuit 84 to deliver a predetermined ventricular pacing pulse synchronized with the sensed P-wave.

[0093] In some examples, the device 10, 310 can be configured to deliver a variety of therapies, including bradycardia pacing, cardiac resynchronization therapy, post-shock pacing, and / or tachycardia-related therapies (such as ATP), etc. For example, the device 10, 310 can be configured to detect non-sinus tachycardia and deliver anti-tachycardia pacing (ATP). The control circuit 80 can determine cardiac event time intervals, such as the PP interval between consecutive P wave sense event signals received from the sensing circuit 86, the RR interval between consecutive R wave sense event signals received from the sensing circuit 86, and the PR and / or RP intervals received between the P wave sense event signal and the R wave sense event signal.

[0094] The therapy delivery circuit 84 may include charging circuitry, one or more charge storage devices (such as one or more low voltage holding capacitors), an output capacitor, and / or switching circuitry that controls the timing of charging and discharging the holding capacitor on the output capacitor to deliver electrical stimulation (e.g., cardiac pacing, defibrillation, cardioversion, etc.) to one or more selected electrodes. The tip electrode 42, 342, the proximal housing-based electrode 24, 324, and the distal housing-based electrode 22, 322 may be selectively coupled to the therapy delivery circuit 84 for delivering atrial pacing pulses, ventricular pacing pulses, defibrillation and cardioversion shocks, etc. The therapy delivery circuit 84 may be configured, for example, to deliver a ventricular pacing pulses upon expiration of an AV or VV pacing interval set by the control circuit 80, for providing atrial synchronized ventricular pacing and a substantially lower ventricular pacing rate. The therapy delivery circuit 84 may be configured to deliver an atrial pacing pulse if the atrial pacing interval expires before a P wave sensing event signal is received from the sensing circuit 86. Control circuit 80 initiates an AV pacing interval in response to the delivered atrial pacing pulse to provide synchronized multi-chamber pacing (eg, dual-chamber or triple-chamber pacing).

[0095] Charging the holding capacitor of therapy circuit 84 to a programmed pacing voltage amplitude and discharging the capacitor to a programmed pacing pulse width may be performed in accordance with control signals received from control circuit 80. For example, a timing circuit included in control circuit 80 may include a programmable digital counter set by a microprocessor of control circuit 80 to control basic time intervals associated with various single-chamber or multi-chamber pacing (e.g., dual-chamber or triple-chamber pacing) modes and anti-tachycardia pacing sequences. The microprocessor of control circuit 80 may also set the amplitude, pulse width, polarity, or other characteristics of the cardiac pacing pulses that may be based on programmed values ​​stored in memory 82.

[0096] The control parameters utilized by the control circuit 80 for sensing cardiac events and controlling the delivery of pacing therapy can be programmed into the memory 82 through 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 communications or other communication protocols. The control circuit 80 can use the telemetry circuit 88 to receive downlink telemetry from the external device and send uplink telemetry to the external device. In some cases, the telemetry circuit 88 can be used to transmit to and receive communication signals from another medical device implanted in the patient.

[0097] The exemplary devices, systems, and methods described herein may be used or configured to provide single-channel cardiac electrical activity using at least one of a right atrial electrode (such as, for example, a distal shell-based electrode 22, a non-tissue-piercing electrode 322, etc.) and a tissue-piercing left ventricular electrode (such as, for example, a tip electrode 42, a tip electrode 342, etc.). One or both of the right atrial electrode and the tissue-piercing left ventricular electrode may be used as a cathode in a sensing pair to provide single-channel cardiac electrical activity. The anode may be a right atrial blood pool electrode, such as, for example, a proximal shell-based electrode 24, a proximal shell-based electrode 324, etc. Additionally, when the tissue-piercing left ventricular electrode is used as a cathode, the right atrial electrode may be used as an anode to form a sensing channel or carrier. In addition, it should be understood that a single sensing channel may be formed or defined using multiple point carriers (e.g., using more electrodes than an electrode pair). In other words, more than two electrodes may be used to form or define a single sensing channel cardiac electrical activity.

[0098] Figure 7 An exemplary method 200 for atrial and ventricular event identification using single channel cardiac electrical activity is depicted in . Generally speaking, it can be described that the exemplary method 200 collects or obtains a single sensing channel cardiac electrical activity and processes the cardiac electrical activity to determine atrial and ventricular events therein.

[0099] As shown, method 200 includes obtaining or monitoring single-channel cardiac electrical activity using electrode pairs or carriers, such as left ventricular electrode to distal right atrium electrode pair 190, distal right atrium electrode to proximal right atrium electrode pair 191, and left ventricular electrode to proximal right atrium electrode pair 192. It should be understood that the left ventricular electrode can be any electrode configured to be positioned close to (e.g., positioned within) left ventricular myocardial tissue, such as any of the tip electrode 42, the tip electrode 342, and any other electrode positioned on the dart electrode assembly 12 as described herein. In addition, it should be understood that the distal right atrium electrode can be any electrode configured to be positioned close to (e.g., adjacent to, in contact with, etc.) right atrial myocardial tissue, such as any of the distal shell-based electrode 22 and the non-tissue piercing electrode 322 as described herein. Still further, it should be understood that the proximal right atrial electrode can be any electrode configured to be positioned proximate to (e.g., positioned within) the right atrial blood pool, such as any of the proximal housing-based electrodes 24, 324 described herein. Additionally, it should be understood that more than a single electrode pair (such as a multi-point sensing carrier) can be utilized to provide a single channel of cardiac electrical activity.

[0100] Thus, single-channel cardiac electrical activity may be provided or obtained 202. Single-channel cardiac electrical activity may be described as a single signal (eg, a sensed or measured voltage) that varies over time. Fig. 9Aillustrative single-channel cardiac electrical activity 300 measured in preclinical animal studies using right atrial electrodes (such as, for example, proximal shell-based electrode 22 and non-tissue piercing electrode 322) and right atrial blood pool electrodes (such as, for example, proximal shell-based electrodes 24, 324).

[0101] Prior to utilizing any further processes to determine atrial and ventricular events within the single channel electrical activity 300, the single channel may be pre-processed 204 using one or more signal processing techniques, algorithms, or procedures such as, for example, filtering, amplification, rectification, etc. For example, Fig. 9B As shown, the single-channel electrical activity 300 has been filtered, amplified, and rectified to produce processed single-channel electrical activity 302. Additionally, the exemplary methods and processes described herein may utilize various comparisons to thresholds, which may be described in terms of greater than, greater than or equal to, less than, and less than or equal to such thresholds. It should be understood that such comparisons may utilize rectified electrical activity, and therefore may utilize absolute values ​​of electrical activity. In other embodiments, the monitored electrical activity may not be corrected, and in such embodiments, the threshold comparisons may be relative or opposite to those described herein.

[0102] In one or more embodiments, before or after preprocessing 204, a derivative of the single channel electrical activity 300 may optionally be generated 206, thereby producing a derived single channel electrical activity that may be further used in the exemplary methods and processes described herein to identify or determine atrial and ventricular events. For example, a slew rate or slope of the single channel electrical activity 300 may be generated and then utilized to identify or determine atrial and ventricular events. If the slew rate of the P wave is lower than the slew rate of the R wave, a first order derivative may enhance signal amplitude separation.

[0103] The method 200 may utilize a sensing threshold to identify or determine a window within the acquired and processed single channel electrical activity 302 that contains or includes atrial events and ventricular events. It should be understood that the sensing threshold may vary depending on the electrodes selected for providing the single channel electrical activity. In one or more embodiments, the sensing threshold may be between about 0.15 millivolts (mV) and about 1.0 mV. In an exemplary embodiment, the sensing threshold may be 0.75 mV, such as by Fig. 9B Indicated by the dashed line 305 in FIG. In one or more exemplary embodiments, the sensing threshold may be a selected percentage of the maximum amplitude of the sensed electrical activity.

[0104] When the electrical activity 302 (eg, its amplitude) exceeds (eg, is greater than) the sensing threshold 208 (eg, Fig. 9B205 ), an event window start time may be determined. A window or portion of electrical activity 302 may then be selected or identified 210, starting from the event window start time and ending when the event window time period expires. The event window time period may be between about 30 milliseconds (ms) and 100 ms. In one embodiment, the event window time period is 40 ms. In one or more embodiments, the event window time period may be greater than or equal to 30 ms, greater than or equal to 40 ms, greater than or equal to 50 ms, greater than or equal to 60 ms, greater than or equal to 70 ms, etc., and / or less than or equal to 100 ms, less than or equal to 90 ms, less than or equal to 80 ms, less than or equal to 65 ms, less than or equal to 55 ms, etc. Fig. 9C A plurality of windows or portions 306A, 306B, 306C, 306D, 306E, 306F covering the processed single channel electrical activity 302 are depicted in FIG.

[0105] Then, the method 200 may determine whether an atrial event or a ventricular event occurs during the window or portion of the electrical activity 302 selected or identified at 210. In other words, one or more of an atrial event and a ventricular event may be determined or identified based on the electrical activity 300, 302 monitored or obtained within the event time window after the determined or identified event window start time. Specifically, the method 200 may compare 212 the window or portion of the electrical activity 302 selected or identified 210 with an A / V threshold. The A / V threshold may be used to determine whether the electrical activity within the identified window or portion represents an atrial event or a ventricular event. The A / V threshold may be between about 1.5 mV and about 2.75 mV. In one embodiment, the A / V threshold is 2.25 mV. In one or more embodiments, the AV threshold may be greater than or equal to 1.5 mV, greater than or equal to 1.75 mV, greater than or equal to 2.0 mV, greater than or equal to 2.1 mV, etc., and / or less than or equal to 2.75 mV, less than or equal to 2.5 mV, less than or equal to 2.4 mV, less than or equal to 2.35 mV, etc.

[0106] If the maximum amplitude of the single-channel electrical activity within the identified portion or window is greater than or equal to the A / V threshold, when a ventricular electrode such as tip electrode 42, 342 is used as a cathode to monitor electrical activity, method 200 may determine that the electrical activity within the identified portion or window is a ventricular event 214. In addition, if the maximum amplitude of the processed single-channel electrical activity within the identified portion or window is greater than or equal to the A / V threshold, when a right atrial electrode (such as, for example, proximal shell-based electrode 22, non-tissue-piercing electrode 322, and proximal shell-based electrodes 24, 324) is used as a cathode to monitor electrical activity, method 200 may determine that the electrical activity within the identified portion or window is an atrial event 216.

[0107] Conversely, if the maximum amplitude of the processed single-channel electrical activity within the identified portion or window is less than the A / V threshold, when the ventricular electrode (such as, for example, the tip electrode 42, 342) is used as the cathode to monitor the electrical activity, the method 200 may determine that the electrical activity within the identified portion or window is an atrial event 216. In addition, if the maximum amplitude of the processed single-channel electrical activity within the identified portion or window is less than the A / V threshold, when the right atrial electrode (such as, for example, the proximal shell-based electrode 22, the non-tissue-piercing electrode 322, and the proximal shell-based electrodes 24, 324) is used as the cathode to monitor the electrical activity, the method 200 may determine that the electrical activity within the identified portion or window is a ventricular event 214.

[0108] In other words, it should be understood that the comparison with the A / V threshold 212 may depend on where the single-channel cardiac electrical activity is sensed from. If the single-channel cardiac electrical activity is sensed near the right atrium (e.g., from the tissue of the right atrium), an atrial event 216 is determined when the maximum amplitude within the window is greater than or equal to the A / V threshold, and a ventricular event 214 is determined when the maximum amplitude within the window is less than the A / V threshold. Conversely, if the single-channel cardiac electrical activity is sensed near the left ventricle (e.g., from the tissue of the left ventricle), a ventricular event is determined 214 when the maximum amplitude within the window is greater than or equal to the A / V threshold, and an atrial event is determined 216 when the maximum amplitude within the window is less than the A / V threshold.

[0109] Fig.9D and Fig.9E , respectively, depicting windows 306A, 306B of processed single-channel cardiac electrical activity 302. As shown, the A / V threshold 307 of 2.25 mV is represented by a dashed line. As described herein, the right atrial electrode and the right atrial blood pool electrode are used to monitor or measure FIG. 9A to FIG. 9B 306A, and thus is monitored or measured near the right atrium (e.g., from tissue of the right atrium). As a result, an atrial event may be determined when the amplitude (e.g., maximum or peak amplitude) of the electrical activity within window 306A is greater than or equal to A / V threshold 307, and a ventricular event may be determined when the amplitude (e.g., maximum or peak amplitude) of the electrical activity within window 306A is less than A / V threshold 307. As shown, the maximum amplitude of the electrical activity 302 within window 306A is greater than or equal to A / V threshold 307 indicating that an atrial event has occurred within window 306A, and the maximum amplitude of the electrical activity 302 within window 306B is less than A / V threshold 307 indicating that a ventricular event has occurred within window 306B.

[0110] Thus, the exemplary method 200 can be described as an amplitude discrimination process, in which the acquired signal is filtered, amplified, and rectified, and then a sensing threshold is applied that is sensitive enough to sense both P waves and R waves. If the signal crosses the sensing threshold, the maximum waveform amplitude can be determined within the event time window after the signal crosses. If the amplitude is below the A / V threshold, it can be classified as an atrial event (e.g., a P wave) or a ventricular event (e.g., an R wave), depending on the electrode used to initially acquire the signal. In addition, the A / V threshold can be configured by the user or can be automatically determined based on a history of previously sensed cardiac events.

[0111] Figure 8 Another exemplary method 201 for atrial and ventricular event identification using single-channel cardiac electrical activity is depicted in FIG. The method 201 may include: Figure 7 Some of the same processes as the method 200 depicted in , such as using the electrode pair 190, 191, 192 to monitor or obtain single-channel cardiac electrical activity 202 and pre-processing the electrical activity 204, will not be further described herein. In short, single-channel cardiac electrical activity can be provided 202 and pre-processed 204. Fig. 10A 4 depicts an exemplary single-channel cardiac electrical activity measurement 400 using a left ventricular electrode (such as, for example, tip electrode 42, 342) and a right atrial blood pool electrode (such as, for example, proximal shell-based electrode 24, 324), and Fig. 10B An exemplary filtered, rectified single-channel cardiac electrical activity 402 is depicted in FIG.

[0112] In method 201, ventricular and atrial thresholds may be utilized to determine or identify ventricular and atrial events. It should be understood that while the exemplary method 201 is specific to electrical activity or signals monitored using a ventricular electrode (such as, for example, tip electrode 42, 342) as a cathode, the teachings of method 201 may be applied to electrical activity monitored using an atrial electrode as a cathode by "swapping" the ventricular and atrial thresholds. Additionally, it should be understood that the ventricular and atrial thresholds may vary depending on the electrode selected for providing a single channel of electrical activity.

[0113] The ventricular threshold may be between about 1.5 mV and about 2.75 mV. In one embodiment, the ventricular threshold is 2.25 mV. In one or more embodiments, the ventricular threshold may be greater than or equal to 1.5 mV, greater than or equal to 1.75 mV, greater than or equal to 2.0 mV, greater than or equal to 2.1 mV, etc., and / or less than or equal to 2.75 mV, less than or equal to 2.5 mV, less than or equal to 2.4 mV, less than or equal to 2.35 mV, etc.

[0114] When the electrical activity 402 exceeds or equals (e.g., is greater than or equal to) the ventricular threshold 220, then the method 200 may determine that the electrical activity is a ventricular event 214. When the electrical activity 402 is less than the ventricular threshold 220, then the method 200 may determine that the electrical activity is not a ventricular event and may proceed to determine whether the electrical activity is an atrial event.

[0115] The atrial threshold may be between about 0.15 mV and about 1.0 mV. In one embodiment, the atrial threshold is 0.75 mV. In one or more embodiments, the atrial threshold may be greater than or equal to 0.5 mV, greater than or equal to 0.6 mV, greater than or equal to 0.7 mV, etc., and / or less than or equal to 1.0 mV, less than or equal to 0.9 mV, less than or equal to 0.8 V, etc. When the electrical activity 402 (e.g., its amplitude) exceeds or equals (e.g., is greater than or equal to) the atrial threshold 222, then the method 200 may determine that the electrical activity is an atrial event 216. When the electrical activity 402 is less than the atrial threshold 222, then the method 200 may determine that the electrical activity is neither a ventricular event nor an atrial event.

[0116] Fig. 10B 405 and an atrial threshold 407, each represented by a dashed line, are depicted in FIG. As shown, an atrial event 406 is determined when the electrical activity or signal 402 is less than the ventricular threshold 405 but greater than or equal to the atrial threshold 407, and a ventricular event 408 is determined when the electrical activity or signal 402 is greater than the ventricular threshold 405.

[0117] Thus, the exemplary method 201 can be described as a dual sensing threshold process, in which the acquired signals are filtered, amplified, and rectified, and any signal that crosses the atrial threshold and does not cross the ventricular threshold can be identified as atrial sensing. In addition, any signal above the ventricular threshold can be identified or determined as ventricular sensing. Each of the atrial threshold and the ventricular threshold can be configured by the user or can be calculated and automatically adjusted based on a history of previously sensed events.

[0118] Additionally, the exemplary method 201 can be described as ignoring or filtering out undesirable portions of a single channel cardiac electrical activity when attempting to identify atrial and ventricular events. For example, when analyzing each of an atrial event or a ventricular event, an atrial threshold and a ventricular threshold can actually be utilized to remove electrical activity that is not related to an atrial event or a ventricular event. As a result, less processing power can be utilized to determine or identify an atrial event or a ventricular event because the irrelevant, undesirable portions of the single channel cardiac electrical activity are not further considered or analyzed.

[0119] Fig.11A, an exemplary single-channel cardiac electrical activity 500 measured using a left ventricular electrode (such as, for example, tip electrode 42, 342) and a right atrial electrode (such as, for example, proximal housing-based electrode 22 and a non-tissue-piercing electrode), and Fig. 11B , an exemplary single-channel cardiac electrical activity 502 is depicted in FIG. Figure 8 The method 201 depicted in Fig. 11B Also depicted are ventricular threshold 505 and atrial threshold 507, each represented by a dashed line. As shown, atrial events 506 are determined when electrical activity or signal 502 is less than ventricular threshold 505 but greater than or equal to atrial threshold 507, and ventricular events 508 are determined when electrical activity or signal 502 is greater than ventricular threshold 505.

[0120] Fig.12 Another exemplary method 203 for atrial and ventricular event identification using single-channel cardiac electrical activity is depicted in FIG. The method 203 may include: Figure 7 Some of the same processes as the method 200 depicted in , such as using one or more of the electrode pairs 190, 191, 192 to monitor or sense single-channel cardiac electrical activity 202, preprocessing the electrical activity 204, comparing the electrical activity to a sensing threshold 208, and windowing the electrical activity 210, are described herein and will not be further described. In short, single-channel cardiac electrical activity may be provided 202, preprocessed 204, and using the sensing threshold 208, various windows or portions of the single-channel electrical activity may be identified or selected 210 for further analysis, such as determining or identifying atrial and ventricular events.

[0121] In method 203, an identified window or portion of the single-channel electrical activity may be identified or determined as an atrial event or a ventricular event using morphology discrimination or comparison 230. More specifically, the monitored electrical activity within the identified window or portion of the single-channel electrical activity may be compared to an atrial electrical morphology template and / or a ventricular electrical morphology template. The atrial electrical morphology template may be a template for a P wave, and the ventricular electrical morphology template may be a template for a QRS complex wave. If the identified window of the single-channel electrical activity substantially matches or is similar to the atrial electrical morphology template, method 203 may determine that the electrical activity is an atrial event 216. Similarly, if the identified window of the single-channel electrical activity substantially matches or is similar to the ventricular electrical morphology template, method 203 may determine that the electrical activity is a ventricular event 214. In other words, atrial events and ventricular events may be determined based on a comparison of the monitored electrical activity with the atrial and ventricular electrical morphology templates. Morphological discrimination or comparison may be further described in U.S. Patent No. 8,983,586, issued on March 17, 2015, which is incorporated herein by reference in its entirety. Additionally, it should be understood that the exemplary methods and processes described herein may utilize one or more morphological metrics (e.g., slew rate, polarity, width, area, etc.) to determine whether the monitored electrical activity within an identified window or portion of the single-channel electrical activity is or includes an atrial event or a ventricular event.

[0122] In one or more embodiments of methods 200, 201, 203, although a single channel of cardiac electrical activity is utilized, the single channel may be processed into two signals: the first signal is a processed signal that is preprocessed according to the process described with respect to preprocessing 204 described herein; and the second signal is the original, unfiltered broadband signal (in other words, the original signal). It should be understood that the second signal may still be low-pass and high-pass filtered to remove baseline variations and high-frequency noise, and is still essentially a broadband signal. The processed signal may be utilized by the sensing 208 and windowing 210 processes, which may produce windows, time periods, or start and end time points that may be applied to the original, unfiltered broadband signal. In other words, the processed signal may be used to select or identify windows or portions of the original, unfiltered broadband signal for further analysis to determine atrial and ventricular events, as described herein with respect to methods 200, 201, 203.

[0123] In other words, a single channel can be separated into a sensed filtered signal and a wideband signal. Processing of the sensed signal can trigger processing of the wideband signal, where amplitude, slew rate, polarity, width, area, template matching, etc. can be used to identify the waveform as a P wave or an R wave with a fixed or patient-specific threshold.

[0124] The techniques described in the present disclosure, including those attributable to IMD 10, device 50, IMD 310, and / or various component parts, may be implemented at least in part in hardware, software, firmware, or any combination thereof. For example, various aspects of the technology may be implemented within one or more processors embodied as a programmer (such as a physician or patient programmer), a stimulator, an image processing device, or other device, the one or more processors comprising one or more microprocessors, DSPs, ASICs, FPGAs, or any other equivalent integrated or discrete logic circuit systems, and any combination of such components. The terms "module," "processor," or "processing circuit system" may collectively refer to any of the aforementioned logic circuit systems alone or in combination with other logic circuit systems, or any other equivalent circuit systems.

[0125] Such hardware, software and / or firmware may be implemented in the same device or in separate devices to support the various operations and functions described in this disclosure. In addition, any described units, modules or components may be implemented together or separately in the form of discrete but interoperable logical devices. Describing different features as modules or units is intended to highlight different functional aspects and does not necessarily imply that such modules or units must be implemented by separate hardware or software components. On the contrary, the functions associated with one or more modules or units may be performed by separate hardware or software components, or integrated in common or separate hardware or software components.

[0126] When implemented in software, the functionality attributed to the systems, devices, and techniques described in this disclosure may be embodied as instructions on a computer-readable medium, such as RAM, ROM, NVRAM, EEPROM, flash memory, magnetic data storage media, optical data storage media, etc. The instructions may be executed by processing circuitry and / or one or more processors to support one or more aspects of the functionality described in this disclosure.

[0127] For all purposes, all references and publications cited herein are expressly incorporated herein by reference in their entirety, unless any aspect of the incorporation directly contradicts the present disclosure. Unless otherwise indicated, all scientific and technical terms used herein have the meanings commonly used in the art. The definitions provided herein are intended to facilitate understanding of certain terms frequently used herein and are not intended to limit the scope of the present disclosure.

[0128] Unless otherwise indicated, all numerical values ​​expressing feature sizes, amounts, and physical properties used in the specification and claims may be understood to be modified by the terms "exactly" or "about." Therefore, unless otherwise indicated, the numerical parameters set forth in the foregoing specification and the appended claims are approximations that may vary depending upon the desired properties sought to be obtained by one skilled in the art utilizing the teachings disclosed herein or, for example, within typical ranges of experimental error.

[0129] The recitation of numerical ranges by endpoints includes all values ​​within the range (e.g., 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, and 5) and any range within the range. As used herein, the term "at most" or "not greater than" a value (e.g., at most 50) includes that value (e.g., 50), and the term "not less than" a value (e.g., not less than 5) includes that value (e.g., 5).

[0130] The terms "coupled" or "connected" refer to elements being directly attached to one another (being in direct contact with one another) or indirectly attached (having one or more elements between and attaching two elements). Both terms may be modified by "operably" and "operably capable of operating," which may be used interchangeably to describe a coupling or connection configured to allow the components to interact to perform at least some function (e.g., a first medical device may be operatively coupled to another medical device to transmit information in the form of data or to receive data therefrom).

[0131] Directional terms such as "top", "bottom", "side" and "end" are used to describe the relative positioning of components and are not meant to limit the orientation of the embodiment under consideration. For example, an embodiment described as having a "top" and a "bottom" also includes embodiments thereof rotated in various orientations, unless the context clearly indicates otherwise.

[0132] References to "one embodiment," "an embodiment," "certain embodiments," or "some embodiments," etc., mean that a particular feature, configuration, composition, or characteristic described in conjunction with the embodiment is included in at least one embodiment of the present disclosure. Thus, the appearance of such phrases in various places throughout the text are not necessarily referring to the same embodiment of the present disclosure. Furthermore, the particular features, configurations, compositions, or characteristics may be combined in any suitable manner in one or more embodiments.

[0133] As used in this specification and the appended claims, the singular forms "a," "an," and "the" encompass embodiments having plural referents, unless the content clearly dictates otherwise. As used in this specification and the appended claims, the term "or" is generally used in its sense, including "and / or," unless the context clearly dictates otherwise.

[0134] As used herein, "having", "including", "comprising", etc. are used in their open-ended sense and generally mean "including but not limited to". It should be understood that "consisting essentially of", "consisting of", etc. are subsumed under "comprising", etc.

[0135] The term "and / or" means one or all of the listed elements or a combination of at least two of the listed elements. The phrases "at least one of," "including at least one of," and "one or more of" accompanying a list refer to any one of the items in the list and any combination of two or more of the items in the list.

[0136] Exemplary Implementation

[0137] Embodiment Em1: An implantable medical device, comprising:

[0138] A plurality of electrodes, the plurality of electrodes comprising:

[0139] a right atrial electrode positionable within the right atrium of the patient's heart, and

[0140] a tissue-piercing electrode implantable through the right atrium from the Koch's triangle region through the right atrial endocardium and the central fiber body and positionable to contact one or more of the basal region, the septal region, and the basal-septal region of the left ventricular myocardium of the patient's heart;

[0141] a therapy delivery circuit operatively coupled to the one or more electrodes to deliver cardiac therapy to the patient's heart;

[0142] sensing circuitry operably coupled to the one or more electrodes to sense electrical activity of the patient's heart; and

[0143] a controller comprising processing circuitry operably coupled to the therapy delivery circuitry and the sensing circuitry, the controller being configured to:

[0144] Single-channel electrical activity is sensed using one or both of: the right atrial electrode capable of being positioned within the right atrium to sense electrical activity within the right atrium, and the tissue-piercing electrode capable of being implanted from the Koch triangle region within the right atrium through the right atrial endocardium and central fiber body into one or more of the basal region, the septal region, and the basal-septal region of the left ventricular myocardium of the patient's heart to sense electrical activity in one or more of the basal region, the septal region, and the basal-septal region of the left ventricular myocardium; and

[0145] Atrial and ventricular events are identified based on the monitored electrical activity.

[0146] Embodiment Em2: A method, the method comprising:

[0147] Single-channel electrical activity is obtained using one or both of: a right atrial electrode positioned within the right atrium to sense electrical activity within the right atrium, and a tissue-piercing electrode implanted from the Koch triangle region within the right atrium through the right atrial endocardium and central fiber body into one or more of the basal region, the septal region, and the basal-septal region of the left ventricular myocardium of the patient's heart to sense electrical activity in one or more of the basal region, the septal region, and the basal-septal region of the left ventricular myocardium; and

[0148] Atrial and ventricular events are identified based on the obtained electrical activity.

[0149] Embodiment Em3: According to the device described in embodiment Em1 or the method described in embodiment Em2, wherein using one or both of the right atrial electrode and the tissue piercing electrode to monitor or obtain the single-channel electrical activity also includes: obtaining the electrical activity between the right atrial electrode and the right atrial blood pool electrode positioned in the right atrial blood pool of the right atrium of the patient's heart.

[0150] Embodiment Em4: A device or method according to any one of embodiments Em1 to Em3, wherein using one or both of the right atrial electrode and the tissue-piercing electrode to monitor or obtain the single-channel electrical activity includes: monitoring or obtaining the electrical activity between the right atrial electrode and the tissue-piercing electrode.

[0151] Embodiment Em5: A device or method according to any one of embodiments Em1 to Em4, wherein identifying atrial events and ventricular events based on the monitored or obtained electrical activity includes: one or more of filtering, amplifying and rectifying the monitored or obtained electrical activity.

[0152] Embodiment Em6: The device or method of any one of Embodiments Em1 to Em5, wherein identifying atrial events and ventricular events based on the monitored or obtained electrical activity comprises:

[0153] When the monitored or obtained electrical activity exceeds a sensing threshold, determining an event window start time; and

[0154] One or more of the atrial event and the ventricular event are determined based on electrical activity monitored or obtained within an event time window after the event window start time.

[0155] Embodiment Em7: The device or method of any one of Embodiments Em1 to Em6, wherein using one or both of the right atrial electrode and the tissue-piercing electrode to monitor or obtain the single-channel electrical activity comprises: using the tissue-piercing electrode as a cathode, wherein identifying atrial events and ventricular events based on the monitored or obtained electrical activity comprises:

[0156] If the monitored or acquired electrical activity is greater than or equal to the atrial / ventricular threshold, determining the ventricular event; and

[0157] If the monitored or acquired electrical activity is less than the atrial / ventricular threshold, then an atrial event is determined.

[0158] Embodiment Em8: The device or method of any one of Embodiments Em1 to Em6, wherein using one or both of the right atrial electrode and the tissue-piercing electrode to monitor or obtain the single-channel electrical activity comprises: using the right atrial electrode as a cathode, wherein identifying atrial events and ventricular events based on the monitored or obtained electrical activity comprises:

[0159] If the monitored or acquired electrical activity is greater than or equal to the atrial / ventricular threshold, determining the atrial event; and

[0160] If the monitored or acquired electrical activity is less than the atrial / ventricular threshold, then the ventricular event is determined.

[0161] Embodiment Em9: The device or method of any one of Embodiments Em1 to Em6, wherein using one or both of the right atrial electrode and the tissue-piercing electrode to monitor or obtain the single-channel electrical activity comprises: using the tissue-piercing electrode as a cathode, wherein identifying atrial events and ventricular events based on the monitored or obtained electrical activity comprises:

[0162] If the monitored or obtained electrical activity is greater than or equal to the ventricular threshold, determining the ventricular event; and

[0163] The atrial event is determined if the monitored or obtained electrical activity is greater than or equal to the atrial threshold, wherein the ventricular threshold is greater than the atrial threshold.

[0164] Embodiment Em10: The device or method of any one of Embodiments Em1 to Em6, wherein using one or both of the right atrial electrode and the tissue-piercing electrode to monitor or obtain the single-channel electrical activity comprises: using the right atrial electrode as a cathode, wherein identifying atrial events and ventricular events based on the monitored or obtained electrical activity comprises:

[0165] If the monitored or obtained electrical activity is greater than or equal to at least a ventricular threshold, determining the ventricular event; and

[0166] The atrial event is determined if the monitored or obtained electrical activity is greater than or equal to at least an atrial threshold, wherein the atrial threshold is greater than the ventricular threshold.

[0167] Embodiment Em11: The device or method of any one of Embodiments Em1 to Em6, wherein identifying atrial events and ventricular events based on the monitored or obtained electrical activity comprises:

[0168] comparing the monitored or acquired electrical activity to one or more of an atrial electrical morphology template and a ventricular electrical morphology template; and

[0169] The atrial and ventricular events are determined based on the comparison of the monitored or obtained electrical activity with one or more of the atrial electrical morphology template and the ventricular electrical morphology template.

[0170] Embodiment Em12: The device or method of any one of Embodiments Em1 to Em6, wherein identifying atrial events and ventricular events based on the monitored or obtained electrical activity comprises:

[0171] filtering the monitored or acquired electrical activity to provide only ventricular electrical activity, thereby generating a ventricular signal;

[0172] determining the ventricular event based on the ventricular signal;

[0173] filtering the monitored or obtained electrical activity to provide only atrial electrical activity, thereby generating an atrial signal; and

[0174] The atrial event is determined based on the atrial signal.

[0175] Embodiment Em13: A device or method according to any one of Embodiments Em1 to Em12, wherein the right atrial electrode and the tissue-piercing electrode are part of a leadless pacemaker.

[0176] Embodiment Em14: A device or method according to embodiment Em13, wherein the leadless pacemaker comprises a housing, wherein the right atrial electrode and the tissue-piercing electrode are leadlessly coupled to the housing.

[0177] Embodiment Em15: A device or method according to embodiment Em14, wherein the housing is fully implantable in the right atrium.

[0178] Embodiment Em16: An implantable medical device, comprising:

[0179] a housing fully implantable in the right atrium of a patient's heart;

[0180] a plurality of electrodes fixed to the housing without leads, the plurality of electrodes comprising:

[0181] a right atrial electrode positionable within the right atrium, and

[0182] a tissue-piercing electrode implantable through the right atrium of the patient so as to extend toward the left ventricular myocardium of the patient's heart; and

[0183] a controller comprising processing circuitry operably coupled to the electrode and within the housing, the controller being configured to:

[0184] monitoring single channel electrical activity using one or both of the right atrial electrode positionable within the right atrium and the tissue piercing electrode implantable through the patient's right atrium so as to extend toward the left ventricular myocardium of the patient's heart; and

[0185] Atrial and ventricular events are identified based on the monitored electrical activity.

[0186] Embodiment Em17: A method comprising:

[0187] obtaining single-channel electrical activity using a fully intracardiac leadless device, using a right atrial electrode of the leadless device positioned within the right atrium of the patient's heart and a tissue-piercing electrode of the leadless device extending toward the left ventricular myocardium of the patient's heart; and

[0188] Atrial and ventricular events are identified based on the obtained electrical activity.

[0189] Embodiment Em18: The device according to embodiment Em16 or the method according to embodiment Em17, wherein using one or both of the right atrial electrode and the tissue piercing electrode to monitor or obtain the single-channel electrical activity also includes: obtaining the electrical activity between the right atrial electrode and the right atrial blood pool electrode positioned in the right atrial blood pool of the right atrium of the patient's heart.

[0190] Embodiment Em19: A device or method according to any one of embodiments Em16 to Em18, wherein using one or both of the right atrial electrode and the tissue-piercing electrode to monitor or obtain the single-channel electrical activity includes: monitoring or obtaining the electrical activity between the right atrial electrode and the tissue-piercing electrode.

[0191] Embodiment Em20: A device or method according to any one of embodiments Em16 to Em19, wherein identifying atrial events and ventricular events based on the monitored or obtained electrical activity includes: one or more of filtering, amplifying and rectifying the monitored or obtained electrical activity.

[0192] Embodiment Em21: The device or method of any one of Embodiments Em16 to Em20, wherein identifying atrial events and ventricular events based on the monitored or obtained electrical activity comprises:

[0193] When the monitored or obtained electrical activity exceeds a sensing threshold, determining an event window start time; and

[0194] One or more of the atrial event and the ventricular event are determined based on electrical activity monitored or obtained within an event time window after the event window start time.

[0195] Embodiment Em22: The device or method of any one of Embodiments Em16 to Em21, wherein using one or both of the right atrial electrode and the tissue-piercing electrode to monitor or obtain the single-channel electrical activity comprises: using the tissue-piercing electrode as a cathode, wherein identifying atrial events and ventricular events based on the monitored or obtained electrical activity comprises:

[0196] If the monitored or acquired electrical activity is greater than or equal to the atrial / ventricular threshold, determining the ventricular event; and

[0197] If the monitored or acquired electrical activity is less than the atrial / ventricular threshold, then an atrial event is determined.

[0198] Embodiment Em23: The device or method of any one of Embodiments Em16 to Em21, wherein identifying atrial events and ventricular events based on the monitored or obtained electrical activity comprises:

[0199] determining the ventricular event based on a comparison of the monitored or obtained electrical activity to at least a ventricular threshold; and

[0200] The atrial event is determined based on a comparison of the monitored or obtained electrical activity to at least an atrial threshold.

[0201] Embodiment Em24: The device or method of any one of Embodiments Em16 to Em21, wherein identifying atrial events and ventricular events based on the monitored or obtained electrical activity comprises:

[0202] comparing the monitored or acquired electrical activity to one or more of an atrial electrical morphology template and a ventricular electrical morphology template; and

[0203] The atrial and ventricular events are determined based on the comparison of the monitored or obtained electrical activity with one or more of the atrial electrical morphology template and the ventricular electrical morphology template.

[0204] Embodiment Em25: The device or method of any one of Embodiments Em16 to Em21, wherein identifying atrial events and ventricular events based on the monitored or obtained electrical activity comprises:

[0205] filtering the monitored or acquired electrical activity to provide only ventricular electrical activity, thereby generating a ventricular signal;

[0206] determining the ventricular event based on the ventricular signal;

[0207] filtering the monitored or obtained electrical activity to provide only atrial electrical activity, thereby generating an atrial signal; and

[0208] The atrial event is determined based on the atrial signal.

[0209] Embodiment Em26: A device or method according to any one of embodiments Em16 to Em21, wherein monitoring or obtaining single-channel electrical activity includes: using a tissue-piercing electrode as a cathode, and identifying atrial events and ventricular events includes determining ventricular events by applying a threshold higher than a threshold applicable to determining atrial events.

[0210] Embodiment Em27: A device or method according to any one of embodiments Em16 to Em21, wherein monitoring or obtaining single-channel electrical activity includes: using the right atrial electrode as a cathode, and identifying atrial events and ventricular events includes determining atrial events by applying a threshold higher than a threshold applicable to determining ventricular events.

[0211] The present disclosure has been provided with reference to exemplary embodiments and aspects, and is not meant to be interpreted in a limiting sense. As previously mentioned, those skilled in the art will recognize that various other exemplary applications can utilize the beneficial properties of the devices, systems, and methods described herein using the techniques as described herein. Various modifications of the exemplary embodiments and aspects, as well as additional embodiments and aspects of the present disclosure, will be apparent after reference to this specification.

Claims

1. An implantable medical device, comprising: A plurality of electrodes, the plurality of electrodes comprising: a right atrial electrode positionable within the right atrium of the patient's heart, and a tissue-piercing electrode implantable through the right atrium from the Koch's triangle region through the right atrial endocardium and the central fiber body and positionable to contact one or more of a basal region, a septal region, and a basal-septal region of the left ventricular myocardium of the patient's heart; a therapy delivery circuit operably coupled to the one or more electrodes to deliver cardiac therapy to the patient's heart; sensing circuitry operably coupled to the one or more electrodes to sense electrical activity of the patient's heart; and a controller comprising processing circuitry operably coupled to the therapy delivery circuitry and the sensing circuitry, the controller being configured to: Single-channel electrical activity is sensed using one or both of: the right atrial electrode capable of being positioned within the right atrium to sense electrical activity within the right atrium, and the tissue-piercing electrode capable of being implanted from the Koch triangle region within the right atrium through the right atrial endocardium and central fiber body into one or more of the basal region, the septal region, and the basal-septal region of the left ventricular myocardium of the patient's heart to sense electrical activity in one or more of the basal region, the septal region, and the basal-septal region of the left ventricular myocardium; and Atrial and ventricular events are identified based on the monitored electrical activity.

2. A method comprising: Single-channel electrical activity is obtained using one or both of: a right atrial electrode positioned within the right atrium to sense electrical activity within the right atrium, and a tissue-piercing electrode implanted from the Koch triangle region within the right atrium through the right atrial endocardium and central fiber body into one or more of the basal region, the septal region, and the basal-septal region of the left ventricular myocardium of the patient's heart to sense electrical activity in one or more of the basal region, the septal region, and the basal-septal region of the left ventricular myocardium; as well as Atrial and ventricular events are identified based on the obtained electrical activity.

3. The apparatus of claim 1 or the method of claim 2, wherein monitoring or obtaining the single-channel electrical activity using one or both of the right atrial electrode and the tissue-piercing electrode further comprises: Electrical activity is obtained between the right atrial electrode and a right atrial blood pool electrode positioned within a right atrial blood pool of the right atrium of the patient's heart.

4. The device or method of any one of claims 1 to 3, wherein monitoring or obtaining the single-channel electrical activity using one or both of the right atrial electrode and the tissue-piercing electrode comprises: Electrical activity between the right atrial electrode and the tissue-piercing electrode is monitored or acquired.

5. The apparatus or method of any one of claims 1 to 4, wherein identifying atrial events and ventricular events based on the monitored or obtained electrical activity comprises: The monitored or obtained electrical activity is one or more of filtered, amplified, and rectified.

6. The apparatus or method of any one of claims 1 to 5, wherein identifying atrial events and ventricular events based on the monitored or obtained electrical activity comprises: determining an event window start time when the monitored or acquired electrical activity exceeds a sensing threshold; as well as One or more of the atrial event and the ventricular event are determined based on electrical activity monitored or obtained within an event time window after the event window start time.

7. The device or method of any one of claims 1 to 6, wherein monitoring or obtaining the single-channel electrical activity using one or both of the right atrial electrode and the tissue-piercing electrode comprises: The tissue-piercing electrode is used as a cathode, wherein identifying atrial events and ventricular events based on the monitored or obtained electrical activity comprises: If the monitored or obtained electrical activity is greater than or equal to the atrial / ventricular threshold, determining the ventricular event; and If the monitored or obtained electrical activity is less than the atrial / ventricular threshold, then the atrial event is determined.

8. The apparatus or method of any one of claims 1 to 6, wherein monitoring or obtaining the single-channel electrical activity using one or both of the right atrial electrode and the tissue-piercing electrode comprises employing the right atrial electrode as a cathode, wherein identifying atrial events and ventricular events based on the monitored or obtained electrical activity comprises: determining said atrial event if the monitored or obtained electrical activity is greater than or equal to an atrial / ventricular threshold; as well as If the monitored or obtained electrical activity is less than the atrial / ventricular threshold, then the ventricular event is determined.

9. The device or method of any one of claims 1 to 6, wherein monitoring or obtaining the single-channel electrical activity using one or both of the right atrial electrode and the tissue-piercing electrode comprises: The tissue-piercing electrode is used as a cathode, wherein identifying atrial events and ventricular events based on the monitored or obtained electrical activity comprises: determining the ventricular event if the monitored or obtained electrical activity is greater than or equal to a ventricular threshold; and The atrial event is determined if the monitored or obtained electrical activity is greater than or equal to an atrial threshold, wherein the ventricular threshold is greater than the atrial threshold.

10. The device or method of any one of claims 1 to 6, wherein monitoring or obtaining the single-channel electrical activity using one or both of the right atrial electrode and the tissue-piercing electrode comprises: The right atrial electrode is used as a cathode, wherein identifying atrial events and ventricular events based on the monitored or obtained electrical activity comprises: determining said ventricular event if the monitored or obtained electrical activity is greater than or equal to at least a ventricular threshold; and The atrial event is determined if the monitored or obtained electrical activity is greater than or equal to at least an atrial threshold, wherein the atrial threshold is greater than the ventricular threshold.

11. The apparatus or method of any one of claims 1 to 6, wherein identifying atrial events and ventricular events based on the monitored or obtained electrical activity comprises: comparing the monitored or obtained electrical activity to one or more of an atrial electrical morphology template and a ventricular electrical morphology template; as well as The atrial and ventricular events are determined based on the comparison of the monitored or obtained electrical activity with one or more of the atrial electrical morphology template and the ventricular electrical morphology template.

12. The apparatus or method of any one of claims 1 to 6, wherein identifying atrial events and ventricular events based on the monitored or obtained electrical activity comprises: filtering the monitored or acquired electrical activity to provide only ventricular electrical activity, thereby generating a ventricular signal; determining the ventricular event based on the ventricular signal; filtering the monitored or obtained electrical activity to provide only atrial electrical activity, thereby generating an atrial signal; as well as The atrial event is determined based on the atrial signal.

13. The device or method of any one of claims 1 to 12, wherein the right atrial electrode and the tissue-piercing electrode are part of a leadless pacemaker.

14. An apparatus or method according to claim 13, wherein the leadless pacemaker comprises a housing, wherein the right atrial electrode and the tissue-piercing electrode are leadlessly coupled to the housing.

15. The device or method of claim 14, wherein the housing is fully implantable in the right atrium.

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