Detection of tachyarrhythmia using VfA device

Abstract

Atrial-to-ventricular (VfA) devices, systems, and methods may be configured to detect tachyarrhythmia. For example, the atrial event rate may be compared to the ventricular rate to determine whether the patient's heart is experiencing tachyarrhythmia. Further, whether the tachyarrhythmia is supraventricular tachycardia or ventricular tachycardia may be determined prior to delivery of a therapy for the treatment of the tachyarrhythmia.

Description

[0001] This application claims the benefit of U.S. Provisional Patent Application Serial No. 63 / 345,830, filed on May 25, 2022, under 35 U.S.C. §119(e), which is incorporated herein by reference in its entirety.

[0002] The disclosure herein relates to atria-to-ventricle (VfA) devices, systems, and methods for use in detecting tachyarrhythmias.

[0003] The cardiac conduction system comprises 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 ventricle via the AV node, which inherently delays conduction to allow the atrium to stop contracting before the ventricle begins 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, can 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 through 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 the 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 provides 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, delivering shock therapy for cardioversion or defibrillation using an IMD or ICD, 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 (AT). 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 therapy 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 devices, systems, and methods relate to atria to ventricles (VfA) devices that can be used for the detection and treatment of tachyarrhythmias. Using one or more electrodes on the exemplary VfA device, atrial and ventricular events, excitation, or contraction rates can be captured or monitored. The exemplary VfA device may include at least a tissue-piercing electrode that is implanted from the Koch triangle region of the right atrium through the right atrial endocardium and the central fibrous body into one or more of the basal region, septal region, and basal-septal region of the left ventricular myocardium of the patient's heart to deliver cardiac therapy in one or more of the basal region, septal region, and basal-septal region of the left ventricular myocardium and sense electrical activity of the left ventricle. In addition, the VfA device may also include a right atrial electrode that can be positioned in the right atrium of the patient's heart to deliver cardiac therapy to the right atrium of the patient's heart and sense electrical activity of the right atrium of the patient's heart.

[0011] An exemplary implantable medical device may include multiple electrodes, which include, in particular: a right atrial electrode, which can be positioned within the right atrium of a patient's heart to deliver cardiac therapy to the right atrium of the patient's heart and sense one or more of the electrical activity of the right atrium of the patient's heart; and a tissue-piercing electrode, which can be implanted into the patient's right atrium from the Koch triangle area of ​​the right atrium through the right atrial endocardium and the central fibrous body, the tissue-piercing electrode being positioned in one or more of the basal region, septal region, and basal-septal region of the left ventricular myocardium of the patient's heart to deliver cardiac therapy and sense one or more of the electrical activity of the left ventricle in one or more of the basal region, septal region, and basal-septal region of the left ventricular myocardium of the patient's heart. The implantable medical device may further include: a therapy delivery circuit that is operably coupled to the multiple electrodes to deliver cardiac therapy to the patient's heart; a sensing circuit that is operably coupled to the multiple electrodes to sense electrical activity of the patient's heart; and a controller that includes a processing circuit system that is operably coupled to the therapy delivery circuit and the sensing circuit.

[0012] In one embodiment, the controller can be configured to: obtain atrial electrical activity of the right atrium and ventricular electrical activity of the left ventricle using one or both of the following: a right atrial electrode positioned within the right atrium of the patient's heart, and a tissue-piercing electrode implanted from the Koch triangle area of ​​the right atrium through the right atrial endocardium and the central fibrous body in one or more of the basal region, septal region, and basal-septal region of the left ventricular myocardium of the patient's heart to sense electrical activity of the left ventricle in one or more of the basal region, septal region, and basal-septal region of the left ventricular myocardium; determine an atrial event rate based on the obtained atrial electrical activity; determine a ventricular event rate based on the obtained ventricular electrical activity; and determine that the patient's heart is experiencing a tachyarrhythmia based on the determined atrial event rate and ventricular event rate.

[0013] In another embodiment, the controller can be configured to: obtain atrial electrical activity of the right atrium and ventricular electrical activity of the left ventricle using one or both of the following: a right atrial electrode positioned within the right atrium of the patient's heart, and a tissue-piercing electrode implanted from the Koch triangle area of ​​the right atrium through the right atrial endocardium and the central fibrous body in one or more of the basal region, septal region, and basal-septal region of the left ventricular myocardium of the patient's heart to sense electrical activity of the left ventricle in one or more of the basal region, septal region, and basal-septal region of the left ventricular myocardium; determine that the patient's heart is experiencing a tachyarrhythmia based on the obtained atrial electrical activity and ventricular electrical activity; and in response to determining that the patient's heart is experiencing a tachyarrhythmia, determine that the patient's heart is experiencing supraventricular tachycardia if the atrial event rate increases before the ventricular event rate.

[0014] An exemplary method may include: obtaining atrial electrical activity of the right atrium and ventricular electrical activity of the left ventricle using one or both of the following: a right atrial electrode positioned within the right atrium of the patient's heart, and a tissue-piercing electrode implanted from the Koch triangle region of the right atrium through the right atrial endocardium and the central fibrous 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; determining an atrial event rate based on the obtained atrial electrical activity, determining a ventricular event rate based on the obtained ventricular electrical activity; and determining that the patient's heart is experiencing a tachyarrhythmia based on the determined atrial event rate and ventricular event rate.

[0015] Another exemplary method may include: obtaining atrial electrical activity of the right atrium and ventricular electrical activity of the left ventricle 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 myocardium of the left ventricle of the patient's heart; determining an atrial event rate based on the obtained atrial electrical activity; determining a ventricular event rate based on the obtained ventricular electrical activity; and determining that the patient's heart is experiencing a tachyarrhythmia based on the determined atrial event rate and ventricular event rate.

[0016] 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

[0017] 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.

[0018] Figure 2 Positioned relative to the patient's cardiac anatomy Figure 1 An enlarged conceptual diagram of the VfA device.

[0019] 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.

[0020] 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.

[0021] Figure 5 is a perspective view of another exemplary VfA device.

[0022] Figure 6 It can be enclosed in, for example Figure 1 to Figure 2 and Figures 4 to 5 A block diagram of the circuitry within the housing of a VfA device to provide an exemplary embodiment of its functions and therapies.

[0023] Figure 7 For example, Figures 1 to 6 Block diagram of an exemplary method for rapid arrhythmia determination and treatment performed by an exemplary system and device.

[0024] Figures 8 to 9 It can be Figures 1 to 6Block diagram of an exemplary method for determining tachyarrhythmia and supraventricular tachycardia performed by an exemplary system and device. DETAILED DESCRIPTION

[0025] 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.

[0026] Will refer to Figures 1 to 9 Describe exemplary devices, systems and methods. It will be apparent to those skilled in the art that an element or process of an embodiment can be used in combination with an element or process of other embodiments, and the possible embodiments of such devices, systems and methods using the combination of features 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.

[0027] The present disclosure describes implantable pacing devices that are configured to sense from the right atrium and left ventricle and provide AV synchronized pacing. 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. Further, although the EV-ICD can provide anti-tachycardia pacing (ATP) for ventricular tachyarrhythmias, the capture threshold may be high, the patient may sense the pacing, and the success rate of terminating ventricular tachyarrhythmias may be low. Therefore, in one or more embodiments, ATP may be delivered from the various exemplary implantable pacing devices described herein.

[0028] Detection of tachyarrhythmias prior to delivery of therapy (e.g., cardioversion, defibrillation, and ATP) can be implemented or performed by an exemplary implantable pacing device as described herein. Specifically, a dual-chamber implantable pacing device including electrodes located near the right atrium and left ventricle (e.g., within the blood pool of the cavity, within the cavity wall, etc.) can be configured to determine or detect tachyarrhythmias and then deliver or actively deliver therapy, such as cardioversion, defibrillation, and ATP. The dual-chamber capabilities of the exemplary implantable medical device (such as atrial and ventricular sensing (e.g., electrical activity monitoring)) can improve the specificity of ventricular tachyarrhythmia detection relative to a single-chamber implantable medical device. Specifically, the exemplary implantable medical devices described herein can utilize various processes that will be further described herein, such as determining whether the sensed ventricular excitation or contraction rate is greater than the sensed atrial excitation or contraction rate, detecting and ignoring unwanted artifacts (e.g., far-field P waves, far-field R waves, and T waves), adding various exemplary discrimination rules to reject supraventricular tachycardias, dynamically discriminating between atrial and ventricular sensed events during and after delivery of anti-tachycardia pacing to improve the specificity of ventricular tachycardia detection, and morphologically processing the QRS morphology of suspected ventricular tachycardias to determine whether they are different from sinus rhythm.

[0029] Further, the exemplary implantable medical device can use an extravascular or subcutaneous implantable cardioverter-defibrillator (ICD) to, for example, deliver cardioversion and defibrillation therapy. Additionally, the extravascular or subcutaneous ICD can help detect or determine tachyarrhythmias, and can actually detect tachyarrhythmias in parallel with the exemplary implantable medical device, and in such a configuration, the detection process and therapy delivery can be modified via the exemplary implantable medical device.

[0030] Thus, the exemplary implantable medical device described herein can improve the specificity of detecting ventricular tachyarrhythmias and provide ATP therapy to terminate ventricular tachyarrhythmias. In addition, the exemplary implantable medical device can work in conjunction with an extravascular or subcutaneous ICD by actively communicating or passive electrogram monitoring to determine the actions of the other device.

[0031] In one or more specific examples, the present disclosure relates to implantable medical devices, systems, and methods for adaptive atrioventricular (VfA) cardiac therapy, which includes 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 implantable medical devices such as pacemakers are referenced herein, the methods and processes can be used with any medical device and system related to or used to treat a patient's heart. Various other applications will become apparent to those skilled in the art who have the benefit of this disclosure.

[0032] It will be appreciated that it may be beneficial to provide an implantable medical device that does not contain a transvenous lead (e.g., a leadless device). It may also be beneficial to provide an implantable medical device that can be used for various cardiac therapies, such as single-chamber or multi-chamber pacing (e.g., dual-chamber or triple-chamber pacing), atrioventricular synchronous pacing, asynchronous pacing, triggered pacing, cardiac resynchronization pacing, or tachycardia-related therapies (such as anti-tachycardia pacing). Further, it may be beneficial to provide a system that can communicate with a separate medical device to, for example, provide triggered pacing or provide shock therapy in certain tachycardia situations.

[0033] The present disclosure provides an implantable medical device, in particular, comprising a tissue piercing electrode and optionally a right atrium electrode. The tissue piercing electrode can be implanted in the base and / or septal region of the left ventricular muscle of the patient's heart from the Koch triangle region of the right atrium through the right atrium endocardium and the central fibrous body. In a leadless implantable medical device, the tissue piercing electrode can extend leadlessly from the distal end region of the housing of the device, and the right atrium electrode can be leadlessly coupled to the housing (e.g., a part of the housing or positioned on the outside of the housing). In a leaded implantable medical device, 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 therewith to trigger or initiate a shock delivered by the IMD.

[0034] 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 and leaded implantable medical devices, the exemplary cardiac therapy system 2 is a leadless IMD 10 implanted in a patient's heart 8.

[0035] IMD 10 can be used to treat at least a cardiac condition by delivering electrical stimulation to one or more regions 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. Further, 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. Still further, for example, IMD 10 can deliver cardioversion or defibrillation shock pulses to one or more parts of the heart. 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).

[0036] 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 on the atrial endocardium in the target implant region 4 within the triangle of Koch. 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 or provide therapy to one or both ventricles (e.g., the right ventricle, the left ventricle, or both ventricles) while typically being positioned in the right atrium. In particular, device 10 may include a tissue-piercing electrode that may be implanted from the Koch triangle region of the right atrium through the right atrial endocardium and central fibrous body into the basal, septal, and / or basal-septal regions of the left ventricular myocardium of the patient's heart.

[0037] 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.

[0038] 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 can 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. In particular, IMD 10 can monitor atrial and ventricular electrical activity to determine or identify atrial and ventricular events (e.g., excitation, contraction, depolarization, etc.), determine whether the patient is experiencing a tachyarrhythmia (e.g., ventricular tachycardia), and deliver therapy to the patient if the patient is experiencing a tachyarrhythmia.

[0039] The device 10 may also include a dart electrode assembly 12 that defines or has a straight shaft extending from a distal 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 central fibrous 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 in 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.

[0040] 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 central fiber body and into the ventricular myocardium 14 or along the ventricular septum without passing completely 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 region of the shaft that may be used, for example, for bipolar sensing, bipolar pacing, or additional sensing for pacing capture.

[0041] The cardiac therapy system 2 may also include a separate medical device 50 (in Figure 1 ), the separate medical device can be positioned outside the patient's heart 8 (e.g., subcutaneously) and can be operably coupled to the patient's heart 8 to deliver cardiac therapy thereto. In one example, the separate medical device 50 can be an extravascular ICD. In some embodiments, the extravascular ICD can include a defibrillation lead that includes or carries a defibrillation electrode. A therapy carrier can exist between the defibrillation electrode on the defibrillation lead and the housing electrode of the ICD. Further, one or more electrodes of the ICD can also be used to sense electrical signals related to the patient's heart 8. The ICD can be configured to deliver shock therapy including one or more defibrillation or cardioversion shocks. For example, if a rapid arrhythmia is sensed, the ICD can send pulses through the 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.

[0042] 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, energy delivered, 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 to 80 joules (J) of energy for subcutaneous defibrillation.

[0043] 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.

[0044] 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 metallic 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.

[0045] 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 cardiac signals and deliver pacing therapy. The IMD device 10 may include a housing 30 defining a hermetically sealed interior cavity, internal components of the device 10 (such as a combination of Figure 6The sensing circuitry, therapy delivery circuitry, control circuitry, memory, telemetry circuitry, other optional sensors, and power supplies described generally reside in the interior cavity. The housing 30 may include (e.g., be formed of or 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 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.

[0046] 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.

[0047] 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 (e.g., defines a conductive material (such as a titanium alloy or other examples listed above), is formed thereof, etc., portions of the housing 30 may be electrically insulated by a non-conductive material (such as a coating of 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 (e.g., defines a non-conductive material (such as a ceramic, glass, or polymer material) or 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.

[0048] 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.

[0049] 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 length. 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.

[0050] 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). As such, 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 may be applied to the tip electrode 42, such as 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).

[0051] 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.

[0052] 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 force, 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.

[0053] The one or more fixing members 20 can be described as having one or more "pointed teeth" with 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 elastically bending back to the normal curved position (as shown) proximally when released from the delivery tool. Further, the fixing member 20 can 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.

[0054] The distal fixation and electrode assembly 36 includes a 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 a proximal shell-based electrode 24 that acts as a return anode electrode. Alternatively, the distal shell-based electrode 22 can act as a return anode electrode paired with a tip electrode 42 for sensing ventricular signals and delivering ventricular pacing pulses. In other examples, the distal shell-based electrode 22 can be a cathode electrode for sensing atrial signals and delivering pacing pulses to the atrial myocardium in the target implant area 4. When the distal shell-based electrode 22 acts as an atrial cathode electrode, the proximal shell-based electrode 24 can act as a return anode paired with the tip electrode 42 for ventricular pacing and sensing, and can act as a return anode paired with the distal shell-based electrode 22 for atrial pacing and sensing.

[0055] As shown in this illustration, in some pacing applications, the target implant 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 implant area 4, through the central fibrous body 16, and into the ventricular myocardium 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 implant area 4, the tip electrode 42 can be placed within the ventricular myocardium 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, including 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.

[0056] 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 the proximal shell-based electrode 24 or as an alternative to the proximal shell-based electrode.

[0057] The acoustic and / or motion detector 11 may also be used for rate response detection or to provide rate responsive IMD. Various techniques related to rate response are described in U.S. Pat. No. 5,154,170, issued Oct. 13, 1992, and U.S. Pat. No. 5,562,711, issued Oct. 8, 1996, each of which is incorporated herein by reference in its entirety.

[0058] 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. Pat. No. 4,546,777, U.S. Pat. No. 6,869,404, U.S. Pat. No. 5,554,177, and U.S. Pat. No. 7,035,684, each of which is incorporated herein by reference in its entirety.

[0059] 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) that is 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.

[0060] 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 subseptal zone 3, basal subseptal zone 4, basal inferolateral zone 5, basal anterior lateral zone 6, mid-anterior zone 7, mid-septal anterior zone 8, mid-inferolateral zone 9, mid-inferolateral zone 10, mid-inferolateral zone 11, mid-anterior lateral zone 12, apical anterior zone 13, apical septal zone 14, apical inferolateral 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 .

[0061] In some embodiments, any tissue-piercing electrode of the present disclosure may be implanted in the basal and / or 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 fibrous body. Once implanted, the tissue-piercing electrode may be positioned in a target implantation region 4(e.g., the basal region, septal region, and / or basal-septal region of the left ventricular myocardium). Figure 1 to Figure 2 ). Referring to FIG100, the basal region includes one or more of the basal anterior region 1, the basal anterior region 2, the basal subseptal region 3, the basal subseptal region 4, the middle anterior region 7, the middle septal anterior region 8, the middle lower septal region 9, and the middle lower region 10. Referring to FIG100, the septal region includes one or more of the basal anterior region 2, the basal anterior region 3, the middle septal anterior region 8, the middle lower septal region 9, and the top septal region 14. The basal-septal region may include one or more of the basal anterior region 2, the basal subseptal region 3, the middle septal anterior region 8, and the middle lower septal region 9.

[0062] 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 can 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 can 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.

[0063] 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 fixation member tines 20a, 20b, and 20c of the fixation 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, bend back to their normal curved position (as shown). When the tines 20a, 20b, and 20c bend back to their normal position, the fixation member 20 can pull the distal fixation member and electrode assembly 36 toward the atrial endocardial surface. When the distal fixation member and electrode assembly 36 is "pulled" toward the atrial endocardium, the tip electrode 42 can be advanced through the atrial muscle and central fibrous body and into the ventricular muscle. The distal housing-based electrode 22 can then be positioned against or adjacent to the atrial endocardial surface.

[0064] 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 that capture myocardium (e.g., atrial muscle tissue). Lower current consumption may save a power source for the device 10, such as one or more rechargeable or non-rechargeable batteries.

[0065] 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 conjunction with the proximal shell-based electrode 24 as a return anode. The electrodes 22 and 24 can be used to sense atrial P waves for controlling atrial pacing pulses (delivered in the absence of a sensed P wave) and for controlling atrial synchronized ventricular pacing pulses delivered using the tip electrode 42 as a cathode and the proximal shell-based electrode 24 as a return anode. In other examples, the distal shell-based electrode 22 can be used as a return anode in conjunction with the cathode tip electrode 42 for ventricular pacing and sensing.

[0066] Figure 5 3 is a 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 can include a housing 330 having an outer sidewall 335 extending from a housing distal region 332 to a housing proximal 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.

[0067] The distal fixation and electrode assembly 336 can be coupled to the housing distal region 332. The distal fixation and electrode assembly 336 can include an electrically insulating distal member 372 coupled to the housing distal region 332. The tissue-piercing electrode assembly 312 can extend away from the housing distal 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 region 332 and can be coaxial with the longitudinal center axis 331 of the housing 330.

[0068] 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 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.

[0069] As described herein, the tip electrode 342 is at or positioned at the shaft distal region 343 and can act as a cathode electrode for delivering ventricular pacing pulses and sensing ventricular electrical signals using the proximal shell-based electrode 324 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 a ring 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.

[0070] The use of two or more tissue-piercing electrodes (e.g., any type of tissue-piercing electrodes) that penetrate into the LV myocardium can be used for more localized pacing capture and can mitigate ventricular pacing spikes that affect capture of atrial tissue. In some embodiments, the plurality of tissue-piercing electrodes can 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.

[0071] 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 isolation elements, which 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.

[0072] 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.

[0073] 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 intermediate 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 intermediate 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.

[0074] 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 close 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 fibrous 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.

[0075] 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 6 As described, the therapy delivery circuit and the sensing circuit are encapsulated by the housing 330. When delivering conventional pacing therapy, the non-tissue piercing electrode 322 can be operated in combination with the proximal housing-based electrode 324 as a return anode to work together for delivering atrial pacing pulses and for sensing atrial electrical signals, such as P waves. The switch circuit system included in the sensing circuit can be activated under the control of the control circuit to couple one or more of the non-tissue piercing electrodes to the atrial 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.

[0076] 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 individual 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.

[0077] 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 such cases, all of the electrodes 322 can be selected together to form an atrial cathode. Alternatively, every other electrode in the electrodes 322 can be selected together to form multiple atrial cathodes with higher electrical impedance, which are 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.

[0078] 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 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.

[0079] 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, and the peripheral edge 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.

[0080] The distal fixation and electrode assembly 336 can seal the distal 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 of the present invention 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.

[0081] 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 senses and paces 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 area 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 area 4 into ventricular tissue to achieve bi-ventricular (right and left ventricle) capture.

[0082] 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 work together to monitor cardiac electrical signals in the atria and ventricles, 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 prohibited, 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 examples, 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.

[0083] 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 general 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 the 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, analog-to-digital converter, switching circuitry, etc.), the sensor 90, the telemetry circuit 88, and the memory 82 to provide power to the various circuits.

[0084] 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.

[0085] 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 circuit systems, cause the control circuit 80 and / or other processing circuit systems to monitor atrial electrical activity 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 activation or contraction), determine atrial events (e.g., atrial activation or contraction), compare QRS morphology to a template indicative of normal sinus rhythm (e.g., a template of 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) attributed to the device 10, 310, or other cardiac therapy functions (e.g., sensing or delivering therapy). Non-transitory computer-readable media storing instructions may include any of the media listed above.

[0086] The control circuit 80 can communicate with the therapy delivery circuit 84 and the sensing circuit 86, for example, via a data bus, to sense cardiac electrical signals and control the delivery of cardiac electrical stimulation therapy in response to sensed cardiac activity (e.g., sensed atrial events and ventricular events, such as P waves / atrial depolarization and R 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 can be electrically coupled to the therapy delivery circuit 84 for delivering electrical stimulation pulses to the sensing circuit 86 and for sensing electrical signals.

[0087] 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 P waves accompanying atrial myocardial depolarization. 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 R waves accompanying ventricular myocardial depolarization.

[0088] As described herein, the sensing circuit 86 may include event detection circuitry for detecting cardiac depolarization activity (e.g., P waves, QRS complexes, R waves, etc.). The event detection circuitry may be configured to amplify, filter, digitize, and rectify electrical signals received from selected electrodes to improve signal quality for cardiac electrical events. The event detection circuitry may include one or more sense amplifiers, filters, rectifiers, threshold detectors, comparators, analog-to-digital converters (ADCs), timers, or other analog or digital components. Event sensing thresholds (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 timing periods and sensing thresholds determined by the control circuit 80, stored in the memory 82, and / or controlled by hardware, firmware, and / or software of the control circuit 80 and / or sensing circuit 86.

[0089] 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 a pacing pulse, depending on a 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.

[0090] 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.

[0091] The therapy delivery circuit 84 may include a charging circuit system, one or more charge storage devices such as one or more low voltage holding capacitors, an output capacitor, and / or a switching circuit system that controls the time at which the holding capacitor is charged and discharged 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 to deliver a ventricular pacing pulses, for example, 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).

[0092] 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.

[0093] 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.

[0094] The example devices, systems, and methods described herein may be used or configured to detect and treat a cardiac condition in a patient. Figure 7An exemplary method 200 for tachyarrhythmia determination and treatment is depicted in . In general, the exemplary method 200 can be described as collecting data from a patient, analyzing the data to determine if a tachyarrhythmia is present that can be treated using cardioversion / defibrillation or anti-tachycardia pacing therapy, and then delivering one or more of cardioversion, defibrillation, and anti-tachycardia pacing therapy.

[0095] As shown, method 200 includes obtaining or monitoring atrial electrical activity of the right atrium 202, and obtaining or monitoring ventricular electrical activity of the left ventricle 204. The electrical activity of the right atrium 202 may be obtained (e.g., measured, sensed, recorded, etc.), and the electrical activity of the left ventricle 204 may be obtained (e.g., measured, sensed, recorded, etc.), using one or more implantable electrodes, such as those described herein. Figure 1 to Figure 2 and Figures 4 to 6 Electrodes 20, 22, 42 of the exemplary IMD 10 described. Although monitoring atrial and ventricular electrical activity 202, 204 is shown as two separate processes in the flowchart of method 200, it should be understood that these processes and the remaining processes of method 200 can occur simultaneously and continuously until these processes are independent of the completion of other processes. For example, obtaining or monitoring atrial and ventricular electrical activity 202, 204, and further processes described herein that can analyze such atrial and ventricular electrical activity can occur continuously throughout method 200.

[0096] As described herein, one or more of the implantable electrodes (such as electrodes 20, 22, 42) can be used to obtain (e.g., monitor, measure, etc.) atrial and ventricular electrical activity 202, 204. More specifically, one or more channels or vectors formed between two or more electrodes (such as electrodes 20, 22, 42) can be used to monitor atrial and ventricular activity 202, 204. In addition, the same or different channels can be used to monitor atrial and ventricular electrical activity. In other words, a single sensing channel can be used to monitor atrial and ventricular electrical activity 202, 204, or a first channel can be used to monitor atrial electrical activity 202, and a second channel different from the first channel can be used to monitor ventricular electrical activity 204. It should be understood that the first channel is different from the second channel, or vice versa, meaning that the first channel uses a different set or combination of electrodes than the second channel to monitor electrical activity.

[0097] In one embodiment, a single sensing channel may be formed using or defined by the tip electrode 42 / 342 and the distal shell-based electrode 22 / 322, and the single channel may be used to monitor both atrial and ventricular electrical activity. When utilizing a single channel, one or more processes may be performed to identify atrial and ventricular events therefrom, such as, for example, atrial and ventricular depolarization, atrial and ventricular excitation, atrial and ventricular contraction, and the like. In one example, one or more undesirable artifacts (such as, for example, P waves, R waves, T waves, noise, and the like) may be removed or filtered 206 from each monitored atrial and ventricular electrical activity, depending on the purpose of the signal. For example, when attempting to obtain only atrial activity from a signal monitored using a single channel formed by the tip electrode 42 / 342 and the distal shell-based electrode 22 / 322, the R wave, T wave, and any other irrelevant activity may be removed or filtered from the signal (which may also be rectified). Additionally, for example, when attempting to acquire only ventricular activity from a signal monitored using a single channel formed by the tip electrode 42 / 342 and the distal shell-based electrode 22 / 322, far-field P waves, T waves, and any other extraneous activity can be removed or filtered from the signal (which can also be rectified). Additionally, it should be understood that what is removed or filtered from the signal can be changed or modified based on the sensing channel or vector selected. One or more devices, systems, methods, and processes utilizing a single sensing channel are described in U.S. patent application Ser. No. 17 / 824,764, entitled “Single Channel Sensing Using VfA Devices” (MDTA0007654), filed by Grinberg et al. on May 25, 2022, which is incorporated herein by reference in its entirety.

[0098] In another embodiment, a single sensing channel may be formed or defined using a tip electrode 42 / 342 and a distal shell-based electrode 22 / 322, and a second sensing channel may be formed or defined using a distal shell-based electrode 22 / 322 and a shell-based proximal electrode 24 / 324. The first sensing channel may be used to monitor ventricular electrical activity, and the second sensing channel may be used to monitor atrial electrical activity. Similar to when a single channel is utilized, one or more processes may be performed to identify atrial events and ventricular events therefrom, such as, for example, atrial and ventricular depolarization, atrial and ventricular excitation, atrial and ventricular contraction, and the like. In one example, one or more undesirable artifacts (such as, for example, P waves, R waves, T waves, noise, and the like) may be removed or filtered 206 from each monitored atrial electrical activity and ventricular electrical activity, depending on the purpose of the signal. For example, when trying to obtain only atrial activity from the second channel signal monitored using the distal shell-based electrode 22 / 322 and the proximal electrode 24 / 324, the far-field R wave, T wave and any other irrelevant activity can be removed or filtered from the signal. In addition, for example, when trying to obtain only ventricular activity from the first channel signal using the tip electrode 42 / 342 and the distal shell-based electrode 22 / 322, the far-field P wave, T wave and any other irrelevant activity can be removed or filtered from the signal.

[0099] Thus, the exemplary method 200 can monitor atrial electrical activity 202, monitor ventricular electrical activity 204, and remove undesirable artifacts 206, such as, for example, cardiac events (e.g., P waves, R waves, T waves) and any other irrelevant activity (e.g., noise) that is not related to the specific monitored activity. In other words, anything that is not related to atrial activity can be removed from the monitored atrial electrical activity, and anything that is not related to ventricular activity can be removed from the monitored ventricular electrical activity.

[0100] In order to determine whether a patient is experiencing a tachyarrhythmia, and can subsequently receive therapy or resolve the tachyarrhythmia, the monitored atrial electrical activity and ventricular electrical activity can be processed or analyzed. For example, the monitored atrial electrical activity can be analyzed to determine or identify atrial events, and the monitored ventricular electrical activity can be monitored to determine or identify ventricular events. Atrial events can include atrial depolarization, excitement, and contraction, such as right atrial depolarization, excitement, and contraction (although the right atrium and left atrium can depolarize and contract relatively simultaneously). Ventricular events can include ventricular depolarization, excitement, and contraction, such as left ventricular depolarization, excitement, and contraction.

[0101] The exemplary method 200 can determine an atrial activation or contraction rate 208 based on the determined or identified atrial events. For example, the number of atrial activations per minute, such as 95 atrial activations per minute, can be determined based on the determined or identified atrial events. In one or more embodiments, events with a maximum amplitude less than or equal to the basic sensing threshold may not be sensed and identified as atrial events.

[0102] Additionally, in one or more embodiments, the atrial contraction rate may be determined to be unreliable 209. For example, if a selected number of atrial events or a plurality of atrial events over a period of time are determined or identified as atrial events, but are also identified or identified as marginal atrial events, the atrial contraction rate may be determined to be unreliable 209. If the atrial contraction rate is determined to be unreliable, the unreliable atrial event data (e.g., the atrial events determined to be unreliable, the portion of the atrial event data determined to be unreliable) and / or the atrial contraction rate may not be used or may be ignored in further processing of the method 200. More specifically, in one example, a subset of marginally identified atrial events may be considered to be “barely sensed” because, for example, such a subset of marginally identified atrial events may exceed a sensing threshold by only a small amount (e.g., by a selected percentage, such as, for example, 10%, 20%, 30%, etc., or by a selected magnitude, such as, for example, 0.1 millivolts (mV), 0.2 mV, 0.3 mV, etc.). The edge-marked events may be classified or identified as unreliable sensed atrial events. Unreliable sensed atrial events may provide an indication of a high risk of under-sensing adjacent events. Thus, identifying a selected number of unreliable sensed atrial events (such as two or more unreliable sensed atrial events out of the last ten sensed atrial events, three or more unreliable sensed atrial events in the past 15 seconds, etc.) within a time period or multiple cardiac cycles may determine that the atrial contraction rate is unreliable 209. Similarly, if a selected time period, such as, for example, 3.0 seconds or less, 2.5 seconds or less, 2.0 seconds or less, 1.75 seconds or less, etc., occurs without an observed atrial event, then the atrial event rate may also be determined to be unreliable.

[0103] The exemplary method 200 may also determine a ventricular activation or contraction rate 210 based on the determined or identified ventricular events. For example, the number of ventricular activations per minute, such as 105 ventricular activations per minute, may be determined based on the determined or identified ventricular events.

[0104] The method 200 can then determine that the patient's heart is experiencing a tachyarrhythmia 220 based on one or more of the determined atrial event rate, the determined ventricular event rate, and the QRS complex morphology of the monitored ventricular electrical activity. In other words, the atrial event rate and the ventricular event rate and the QRS complex morphology of the monitored ventricular electrical activity can be used to calculate or analyze whether the patient's heart is experiencing a tachyarrhythmia 220. Figures 8 to 9 An exemplary embodiment of determining whether a patient's heart is experiencing a tachyarrhythmia 220 is further described.

[0105] If it is determined that the patient's heart is experiencing a tachyarrhythmia 220, then before delivering therapy, method 200 can determine whether the determined or detected tachyarrhythmia is a supraventricular tachycardia 222, which can be described as a tachycardia that originates outside the ventricles, such as, for example, atrioventricular nodal reentrant tachycardia, atrioventricular reentrant tachycardia, and atrial tachycardia (e.g., including atrial flutter and atrial fibrillation). If supraventricular tachycardia is determined 222, method 200 can not deliver any therapy and can simply continue to monitor atrial and ventricular electrical activity 202, 204 and analyze such atrial and ventricular electrical activity using processes 206, 208, 210, or can deliver atrial anti-tachycardia pacing therapy 228. Exemplary anti-tachycardia pacing therapies may be described in US Pat. No. 6,876,880, issued May 5, 2005, which is incorporated herein by reference in its entirety.

[0106] If supraventricular tachycardia is not determined 222, the method 200 can deliver one or both of cardioversion / defibrillation therapy 224 and ventricular anti-tachycardia pacing therapy 226. Depending on the capabilities of the IMD 10 and the stand-alone device 50, the cardioversion / defibrillation therapy 224 can include one or both of cardioversion therapy and defibrillation therapy. In one or more embodiments, the IMD 10 can initiate or trigger a separate device 50, such as an ICD, to deliver one or both of cardioversion therapy and defibrillation therapy. In one or more embodiments, the IMD 10 can utilize one or more of the electrodes 22 / 322, 24 / 324, 42 / 342 to deliver one or both of cardioversion therapy and defibrillation therapy. Cardioversion and defibrillation therapy may be further described in U.S. Pat. No. 4,595,009, issued June 17, 1986; U.S. Pat. No. 4,548,209, issued October 22, 1985; U.S. Pat. No. 4,693,253, issued September 15, 1987; U.S. Pat. No. 4,935,551, issued September 4, 1990; and U.S. Pat. No. 5,163,427, issued November 17, 1992, all of which are incorporated herein by reference in their entirety.

[0107] Similarly, ventricular anti-tachycardia pacing therapy 226 can be delivered via one or both of the IMD 10 and a separate device. In one or more embodiments, the IMD 10 can utilize one or more of the electrodes 22 / 322, 24 / 324, 42 / 342 to deliver ventricular anti-tachycardia pacing therapy. Ventricular anti-tachycardia pacing therapy may include one or more pacing pulses delivered earlier than expected ventricular excitation (e.g., depolarization or contraction) that are configured to terminate the tachycardia. In one or more embodiments, the ventricular anti-tachycardia pacing therapy can measure the RR interval and deliver the pacing pulse after a period that is a fraction or percentage of the RR interval measured after ventricular excitation. Ventricular antitachycardia pacing may be further described in U.S. Patent No. 5,243,397, issued September 14, 1993, and U.S. Patent No. 7,177,683, issued February 13, 2007, which are incorporated herein by reference in their entirety.

[0108] During the delivery of ventricular antitachycardia pacing therapy 226, method 200 may continue to determine whether the patient's heart is experiencing supraventricular tachycardia 222 based on the atrial and ventricular electrical activity monitored during and after or subsequently to the delivery of the ventricular antitachycardia pacing therapy. In other words, the atrial and ventricular electrical activity may continue to be monitored throughout, during, and after the delivery of the ventricular antitachycardia pacing therapy, and then the atrial and ventricular electrical activity may be used to determine whether the patient's heart is experiencing supraventricular tachycardia 222. In at least one embodiment, antitachycardia pacing therapy may be delivered to the atria and ventricles, and then the atrial and ventricular electrical activity may be monitored to determine whether the patient's heart is experiencing supraventricular tachycardia. Exemplary methods and processes related to distinguishing tachycardia using atrial-ventricular pacing may be described in U.S. Patent No. 8,831,723, issued September 8, 2009, which is incorporated herein by reference in its entirety.

[0109] References Figures 8 to 9 Described is an exemplary embodiment of determining whether the patient's heart is experiencing ventricular tachycardia or supraventricular tachycardia. Thus, prior to method 240 or method 241, it has been determined that the patient is experiencing a tachyarrhythmia, but it has not yet been determined whether the tachyarrhythmia is ventricular tachycardia or supraventricular tachycardia. Additionally, in some embodiments, Figure 8 and / or Fig. 9 The process can be Figure 7 , for example, at box or process 222 thereof.

[0110] Figure 8 The method 240 may include comparing the ventricular event rate (V rate) and the atrial event rate (A rate) 241. Typically, if the atrial event rate (A rate) is greater than the ventricular event rate (V rate), it can be determined that the patient is experiencing supraventricular tachycardia 242, and if the atrial event rate (A rate) is less than the ventricular event rate (V rate), a further process can be performed to determine whether the patient is experiencing tachyarrhythmia or supraventricular tachycardia. In this embodiment, a margin n% is further utilized. Thus, if the A rate is greater than n% of the V rate, it can be determined that the patient is experiencing supraventricular tachycardia 242, and if the A rate is less than n% of the V rate, a further process can be performed to determine whether the patient is experiencing tachyarrhythmia or supraventricular tachycardia. The margin n% can be between about 102% and about 115%. In at least one embodiment, the margin n% is 106%.

[0111] If the A rate is approximately equal to the V rate (e.g., within 6%), the method 240 can determine which chamber, the atria or the ventricles, has an accelerating event rate first 250. In other words, the method 240 can determine which of the V rate or the A rate increases first. If the A rate increases before the V rate, it can be determined that the patient is experiencing supraventricular tachycardia 242. In other words, if the atrial event rate increases before the ventricular event rate increases, it can be determined that the patient is experiencing supraventricular tachycardia 242. Conversely, if the V rate increases before the A rate, it can be determined that the patient is experiencing ventricular tachycardia 244. In other words, if the ventricular event rate increases before the atrial event rate increases, it can be determined that the patient is experiencing ventricular tachycardia 244.

[0112] Typically, if the ventricular event rate (V rate) is greater than the atrial event rate (A rate), the method 240 can confirm whether the determined or identified atrial events are reliably sensed or identified based on the atrial electrical activity 252. For example, if the atrial electrical activity or the sensed atrial events (e.g., their amplitude and / or maximum amplitude) is within a selected percentage of the basic sensing threshold or close to the basic sensing threshold, the atrial event rate can be determined to be unreliable. In one embodiment, the selected percentage can be 25%. Further, in one or more embodiments, if a selected number or percentage of atrial events are determined to be unreliable (e.g., close to the sensing threshold), the atrial event rate can be determined to be unreliable. For example, if the monitored atrial electrical activity corresponding to more than 3 atrial events in the past 10 atrial events is a selected percentage of the basic sensing threshold or close to the basic sensing threshold, the atrial event rate can be determined to be unreliable. Further, for example, if the monitored atrial electrical activity corresponding to 30% of the atrial events in the previous 8 seconds is a selected percentage of the basic sensing threshold or close to the basic sensing threshold, the atrial event rate can be determined to be unreliable. Likewise, if a selected time period, such as, for example, 3.0 seconds or less, 2.5 seconds or less, 2.0 seconds or less, 1.75 seconds or less, etc., occurs without an observed atrial event, then the atrial event rate may be determined to be unreliable. Additionally, in one or more embodiments, if the atrial event rate is determined to be unreliable, ventricular morphology may be utilized to determine or distinguish between ventricular tachycardia and supraventricular tachycardia, similarly as described herein with respect to process 254.

[0113] If the atrial event rate is determined to be unreliable, then it may be determined that the patient is experiencing supraventricular tachycardia 242 , and conversely, if the atrial event rate is determined to be reliable, then it may be determined that the patient is experiencing ventricular tachycardia 242 .

[0114] Fig. 9 Method 260 may include the following: Figure 8The same processes 241, 250, 252 as described in the method 240 will not be further described herein. The method 260 further includes a QRS morphology comparison process 254 in response to the comparison of the A rate to the V rate 241, and determining that the A rate is approximately equal to the V rate (e.g., within 6%) 241. The QRS morphology comparison process 254 can compare the QRS morphology of the monitored ventricular electrical activity with a QRS morphology template representing normal sinus rhythm. If the QRS morphology of the monitored ventricular electrical activity approximately matches the QRS morphology template representing normal sinus rhythm, the process 250 of determining which chamber of the atrium or ventricle first has an accelerated event rate can be performed or implemented. If the QRS morphology of the monitored ventricular electrical activity does not approximately match the QRS morphology template representing normal sinus rhythm, it can be determined that the patient is experiencing ventricular tachycardia 242.

[0115] The techniques described in the present disclosure, including those attributable to IMD 10, device 50, IMD 310, and / or various constituent components, 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.

[0116] 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 logic 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.

[0117] 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.

[0118] 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.

[0119] 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.

[0120] 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).

[0121] 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).

[0122] 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.

[0123] 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.

[0124] 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.

[0125] 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.

[0126] 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.

[0127] Exemplary Implementation

[0128] Embodiment Em1: An implantable medical device, comprising:

[0129] A plurality of electrodes, the plurality of electrodes comprising:

[0130] a right atrial electrode positionable within the right atrium of a patient's heart to one or more of deliver cardiac therapy to the right atrium of the patient's heart and sense electrical activity in the right atrium of the patient's heart; and

[0131] a tissue-piercing electrode capable of being implanted into the right atrium of a patient from the Koch triangle region of the right atrium through the right atrial endocardium and the central fibrous body, the tissue-piercing electrode being positioned in 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 to perform one or more of delivering cardiac therapy and sensing electrical activity of the left ventricle in 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;

[0132] a therapy delivery circuit operably coupled to the plurality of electrodes to deliver cardiac therapy to the patient's heart;

[0133] sensing circuitry operably coupled to the plurality of electrodes to sense electrical activity of the patient's heart; and

[0134] a controller comprising processing circuitry operably coupled to the therapy delivery circuitry and the sensing circuitry, the controller being configured to:

[0135] obtaining the atrial electrical activity of the right atrium and the ventricular electrical activity of the left ventricle using one or both of: the right atrial electrode positioned in the right atrium of the patient's heart, and the tissue-piercing electrode implanted from the Koch triangle region of the right atrium through the right atrial endocardium and central fibrous 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 the electrical activity of the left ventricle in one or more of the basal region, the septal region, and the basal-septal region of the left ventricular myocardium;

[0136] determining an atrial event rate based on the obtained atrial electrical activity;

[0137] determining a ventricular event rate based on the obtained ventricular electrical activity; and

[0138] It is determined that the patient's heart is experiencing a tachyarrhythmia based on the determined atrial event rate and ventricular event rate.

[0139] Embodiment Em2: A method comprising:

[0140] atrial electrical activity of the right atrium and ventricular electrical activity of the left ventricle are obtained using one or both of: a right atrial electrode positioned within the right atrium of the patient's heart, and a tissue-piercing electrode implanted from the Koch triangle region of the right atrium through the right atrial endocardium and central fibrous body into 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;

[0141] determining an atrial event rate based on the obtained atrial electrical activity;

[0142] determining a ventricular event rate based on the obtained ventricular electrical activity; and

[0143] It is determined that the patient's heart is experiencing a tachyarrhythmia based on the determined atrial event rate and ventricular event rate.

[0144] Embodiment Em3: A device according to embodiment Em1 or a method according to embodiment Em2, wherein determining that the patient's heart is experiencing a tachyarrhythmia based on the determined atrial event rate and ventricular event rate includes determining that the patient's heart is experiencing a ventricular tachyarrhythmia in response to the ventricular event rate being greater than the atrial event rate.

[0145] Embodiment Em4: A device or method according to any one of embodiments Em1 to Em2, wherein the controller is further configured to perform the following operations or the method further includes: before determining the atrial event rate and the ventricular event rate, removing unwanted artifacts from each of the obtained atrial electrical activity and ventricular electrical activity, the artifacts including one or more of P waves, R waves and T waves.

[0146] Embodiment Em5: The device or method of any one of Embodiments Em1 to Em4, wherein the controller is further configured to perform the following operations or the method further comprises: in response to determining that the patient's heart is experiencing a tachyarrhythmia:

[0147] determining that the patient's heart is experiencing supraventricular tachycardia based on the obtained atrial electrical activity and ventricular electrical activity; and

[0148] Anti-tachycardia pacing therapy is inhibited in response to determining that the patient's heart is experiencing the supraventricular tachycardia.

[0149] Embodiment Em6: A device or method according to any one of embodiments Em1 to Em4, wherein the controller is further configured to perform the following operations or the method further includes: in response to determining that the patient's heart is experiencing a rapid arrhythmia, if the atrial event rate increases before the ventricular event rate, determining that the patient's heart is experiencing supraventricular tachycardia.

[0150] Embodiment Em7: The device or method of any one of Embodiments Em1 to Em6, wherein the controller is further configured to perform the following operations or the method further comprises: in response to determining that the patient's heart is experiencing a tachyarrhythmia:

[0151] delivering anti-tachycardia pacing therapy using one or both of the right atrial electrode and the tissue-piercing electrode;

[0152] It is determined that the patient's heart is experiencing supraventricular tachycardia based on atrial and ventricular electrical activity obtained after delivery of anti-tachycardia pacing therapy.

[0153] Embodiment Em8: The device or method of any one of Embodiments Em1 to Em7, wherein determining that the patient's heart is experiencing a tachyarrhythmia is further based on the obtained QRS complex morphology of the ventricular electrical activity.

[0154] Embodiment Em9: A device or method according to embodiment Em8, wherein determining that the patient's heart is experiencing rapid arrhythmia based on the obtained QRS complex morphology of ventricular electrical activity includes: comparing the QRS complex morphology with a QRS complex morphology template indicating normal sinus rhythm.

[0155] Embodiment Em10: The device or method according to any one of embodiments Em8 to Em9, wherein the controller is further configured to perform the following operations or the method further includes: determining that the atrial event rate is unreliable based on the obtained atrial electrical activity is unreliable.

[0156] Embodiment Em11: The device or method of any one of Embodiments Em1 to Em10, wherein the controller is further configured to perform the following operations or the method further comprises: in response to determining that the patient's heart is experiencing a tachyarrhythmia:

[0157] determining that the patient's heart is experiencing supraventricular tachycardia based on the obtained atrial electrical activity and ventricular electrical activity; and

[0158] If the patient's heart is experiencing supraventricular tachycardia, at least the right atrial electrode is used to deliver atrial anti-tachycardia pacing therapy.

[0159] Embodiment Em12: A device or method according to any one of embodiments Em1 to Em11, wherein the controller is further configured to perform the following operations or the method further includes: in response to determining that the patient's heart is experiencing a rapid arrhythmia, at least using the tissue piercing electrode to deliver anti-tachycardia pacing therapy.

[0160] Embodiment Em13: A device or method according to any one of embodiments Em1 to Em12, wherein the controller is further configured to perform the following operations or the method further includes: in response to determining that the patient's heart is experiencing a tachyarrhythmia, communicating with an implantable cardioverter-defibrillator to initiate delivery of cardioversion or defibrillation shock therapy from the implantable cardioverter-defibrillator.

[0161] Embodiment Em14: An implantable medical device, comprising:

[0162] A plurality of electrodes, the plurality of electrodes comprising:

[0163] a right atrial electrode positionable within the right atrium of a patient's heart to one or more of deliver cardiac therapy to the right atrium of the patient's heart and sense electrical activity in the right atrium of the patient's heart; and

[0164] a tissue-piercing electrode capable of being implanted into the right atrium of a patient from the Koch triangle region through the right atrial endocardium and central fibrous body, the tissue-piercing electrode being positioned in 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 perform one or more of delivering cardiac therapy and sensing electrical activity of the left ventricle in 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;

[0165] a therapy delivery circuit operably coupled to the plurality of electrodes to deliver cardiac therapy to the patient's heart;

[0166] sensing circuitry operably coupled to the plurality of electrodes to sense electrical activity of the patient's heart; and

[0167] a controller comprising processing circuitry operably coupled to the therapy delivery circuitry and the sensing circuitry, the controller being configured to:

[0168] obtaining the atrial electrical activity of the right atrium and the ventricular electrical activity of the left ventricle using one or both of: the right atrial electrode positioned in the right atrium of the patient's heart, and the tissue-piercing electrode implanted from the Koch triangle region of the right atrium through the right atrial endocardium and central fibrous 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 the electrical activity of the left ventricle in one or more of the basal region, the septal region, and the basal-septal region of the left ventricular myocardium;

[0169] Determining that the patient's heart is experiencing a tachyarrhythmia based on the obtained atrial electrical activity and ventricular electrical activity; and

[0170] In response to determining that the patient's heart is experiencing the tachyarrhythmia, if an atrial event rate increases before a ventricular event rate, then the patient's heart is determined to be experiencing supraventricular tachycardia.

[0171] Embodiment Em15: A method comprising:

[0172] obtaining, with a fully intracardiac leadless device, atrial electrical activity of the right atrium and ventricular electrical activity of the left ventricle 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;

[0173] determining an atrial event rate based on the obtained atrial electrical activity;

[0174] determining a ventricular event rate based on the obtained ventricular electrical activity; and

[0175] It is determined that the patient's heart is experiencing a tachyarrhythmia based on the determined atrial event rate and ventricular event rate.

[0176] Embodiment Em16: A device according to embodiment Em14 or a method according to embodiment Em15, wherein determining that the patient's heart is experiencing a tachyarrhythmia includes determining that the patient's heart is experiencing a ventricular tachyarrhythmia in response to a ventricular event rate being greater than an atrial event rate.

[0177] Embodiment Em17: A device or method according to any one of embodiments Em14 to Em16, wherein the controller is further configured to perform the following operations or the method further includes: inhibiting anti-tachycardia pacing therapy in response to determining that the patient's heart is experiencing the supraventricular tachycardia.

[0178] Embodiment Em18: The device or method of any one of Embodiments Em14 to Em17, wherein the controller is further configured to perform the following operations or the method further comprises: in response to determining that the patient's heart is experiencing a tachyarrhythmia:

[0179] delivering anti-tachycardia pacing therapy using one or both of the right atrial electrode and the tissue-piercing electrode;

[0180] It is determined that the patient's heart is experiencing supraventricular tachycardia based on atrial and ventricular electrical activity obtained after delivery of anti-tachycardia pacing therapy.

[0181] Embodiment Em19: The device or method of any one of Embodiments Em14 to Em18, wherein determining that the patient's heart is experiencing a tachyarrhythmia is further based on the obtained QRS complex morphology of the ventricular electrical activity.

[0182] Embodiment Em20: A device or method according to any one of embodiments Em14 to Em19, wherein the controller is further configured to perform the following operations or the method further includes: in response to determining that the patient's heart is experiencing supraventricular tachycardia, delivering atrial anti-tachycardia pacing therapy using at least the right atrial electrode of the patient's heart.

[0183] Embodiment Em21: A device or method according to any one of embodiments Em14 to Em20, wherein the controller is further configured to perform the following operations or the method further includes: in response to determining that the patient's heart is experiencing a rapid arrhythmia, at least using the tissue piercing electrode to deliver anti-tachycardia pacing therapy.

[0184] 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 a patient's heart to one or more of deliver cardiac therapy to the right atrium of the patient's heart and sense electrical activity in the right atrium of the patient's heart; and a tissue-piercing electrode capable of being implanted through the right atrium of a patient from a region of Koch's triangle through the right atrial endocardium and the central fibrous body, the tissue-piercing electrode being positioned in 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 to one or more of delivering cardiac therapy and sensing electrical activity of the left ventricle in 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; a therapy delivery circuit operably coupled to the plurality of electrodes to deliver cardiac therapy to the patient's heart; sensing circuitry operably coupled to the plurality of 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: obtaining the atrial electrical activity of the right atrium and the ventricular electrical activity of the left ventricle using one or both of: the right atrial electrode positioned in the right atrium of the patient's heart, and the tissue-piercing electrode implanted from the Koch triangle region of the right atrium through the right atrial endocardium and central fibrous 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 the electrical activity of the left ventricle in one or more of the basal region, the septal region, and the basal-septal region of the left ventricular myocardium; determining an atrial event rate based on the obtained atrial electrical activity; determining a ventricular event rate based on the obtained ventricular electrical activity; and It is determined that the patient's heart is experiencing a tachyarrhythmia based on the determined atrial event rate and ventricular event rate.

2. A method comprising: atrial electrical activity of the right atrium and ventricular electrical activity of the left ventricle are obtained using one or both of: a right atrial electrode positioned within the right atrium of the patient's heart, and a tissue-piercing electrode implanted from the Koch triangle region of the right atrium through the right atrial endocardium and central fibrous 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; determining an atrial event rate based on the obtained atrial electrical activity; determining a ventricular event rate based on the obtained ventricular electrical activity; as well as It is determined that the patient's heart is experiencing a tachyarrhythmia based on the determined atrial event rate and ventricular event rate.

3. The apparatus of claim 1 or the method of claim 2, wherein determining that the patient's heart is experiencing a tachyarrhythmia based on the determined atrial event rate and ventricular event rate comprises: In response to the ventricular event rate being greater than the atrial event rate, it is determined that the patient's heart is experiencing a ventricular tachyarrhythmia.

4. The device or method according to any one of claims 1 to 2, wherein the controller is further configured to perform the following operations or the method further comprises: Prior to determining the atrial event rate and the ventricular event rate, undesirable artifacts are removed from each of the obtained atrial electrical activity and ventricular electrical activity, the artifacts including one or more of a P wave, an R wave, and a T wave.

5. The device or method according to any one of claims 1 to 4, wherein the controller is further configured to perform the following operations or the method further comprises: In response to determining that the patient's heart is experiencing a tachyarrhythmia: determining that the patient's heart is experiencing supraventricular tachycardia based on the obtained atrial electrical activity and ventricular electrical activity; as well as Anti-tachycardia pacing therapy is inhibited in response to determining that the patient's heart is experiencing the supraventricular tachycardia.

6. The device or method according to any one of claims 1 to 4, wherein the controller is further configured to perform the following operations or the method further comprises: In response to determining that the patient's heart is experiencing a tachyarrhythmia, if the atrial event rate increases before the ventricular event rate, then the patient's heart is determined to be experiencing a supraventricular tachycardia.

7. The device or method according to any one of claims 1 to 6, wherein the controller is further configured to perform the following operations or the method further comprises: In response to determining that the patient's heart is experiencing a tachyarrhythmia: delivering anti-tachycardia pacing therapy using one or both of the right atrial electrode and the tissue-piercing electrode; as well as It is determined that the patient's heart is experiencing supraventricular tachycardia based on atrial and ventricular electrical activity obtained after delivery of anti-tachycardia pacing therapy.

8. The device or method of any one of claims 1 to 7, wherein determining that the patient's heart is experiencing a tachyarrhythmia is further based on the obtained QRS complex morphology of the ventricular electrical activity.

9. The apparatus or method of claim 8, wherein determining that the patient's heart is experiencing a tachyarrhythmia based on the obtained QRS complex morphology of the ventricular electrical activity comprises: The QRS complex morphology is compared to a QRS complex morphology template indicative of normal sinus rhythm.

10. The device or method according to any one of claims 8 to 9, wherein the controller is further configured to perform the following operations or the method further comprises: The atrial event rate is determined to be unreliable based on the obtained atrial electrical activity being unreliable.

11. The device or method according to any one of claims 1 to 10, wherein the controller is further configured to perform the following operations or the method further comprises: In response to determining that the patient's heart is experiencing a tachyarrhythmia: determining that the patient's heart is experiencing supraventricular tachycardia based on the obtained atrial electrical activity and ventricular electrical activity; as well as If the patient's heart is experiencing supraventricular tachycardia, at least the right atrial electrode is used to deliver atrial anti-tachycardia pacing therapy.

12. The device or method according to any one of claims 1 to 11, wherein the controller is further configured to perform the following operations or the method further comprises: In response to determining that the patient's heart is experiencing a tachyarrhythmia, anti-tachycardia pacing therapy is delivered using at least the tissue-piercing electrode.

13. The device or method according to any one of claims 1 to 12, wherein the controller is further configured to perform the following operations or the method further comprises: In response to determining that the patient's heart is experiencing a tachyarrhythmia, communicating with an implantable cardioverter-defibrillator to initiate delivery of a cardioversion or defibrillation shock therapy from the implantable cardioverter-defibrillator.

14. An implantable medical device, comprising: A plurality of electrodes, the plurality of electrodes comprising: a right atrial electrode positionable within the right atrium of a patient's heart to one or more of deliver cardiac therapy to the right atrium of the patient's heart and sense electrical activity in the right atrium of the patient's heart; and a tissue-piercing electrode capable of being implanted into the right atrium of a patient from the Koch triangle region through the right atrial endocardium and central fibrous body, the tissue-piercing electrode being positioned in 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 to perform one or more of delivering cardiac therapy and sensing electrical activity of the left ventricle in 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; a therapy delivery circuit operably coupled to the plurality of electrodes to deliver cardiac therapy to the patient's heart; sensing circuitry operably coupled to the plurality of 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: The atrial electrical activity of the right atrium and the ventricular electrical activity of the left ventricle are obtained using one or both of the following: the right atrial electrode positioned in the right atrium of the patient's heart, and the tissue-piercing electrode implanted from the Koch triangle area of ​​the right atrium through the right atrial endocardium and the central fibrous 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 the electrical activity of the left ventricle in one or more of the basal region, the septal region, and the basal-septal region of the left ventricular myocardium; Determining that the patient's heart is experiencing a tachyarrhythmia based on the obtained atrial electrical activity and ventricular electrical activity; and In response to determining that the patient's heart is experiencing the tachyarrhythmia, if an atrial event rate increases before a ventricular event rate, then the patient's heart is determined to be experiencing supraventricular tachycardia.

15. A method comprising: obtaining, with a fully intracardiac leadless device, atrial electrical activity of the right atrium and ventricular electrical activity of the left ventricle 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; determining an atrial event rate based on the obtained atrial electrical activity; determining a ventricular event rate based on the obtained ventricular electrical activity; as well as It is determined that the patient's heart is experiencing a tachyarrhythmia based on the determined atrial event rate and ventricular event rate.

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