Capture in atrium-to-ventricle cardiac therapy

Abstract

Atria-to-ventricle (VfA) cardiac therapy can utilize a tissue-penetrating electrode implanted from the right atrium through the right atrial endothelium and the central fibrous body into the left ventricular myocardium of a patient's heart. The example apparatus and method can determine whether the tissue-penetrating electrode is achieving effective left ventricular capture. Additionally, one or more pacing parameters or pacing settings can be adjusted based on an effective left ventricular capture determination.

Description

[0001] This application claims the benefit of U.S. Provisional Application Serial No. 62 / 736,905, filed September 26, 2018, the entire contents of which are incorporated herein by reference.

[0002] The present disclosure relates generally to medical implantable devices and methods for atrium-to-ventricle (VfA) cardiac therapy. More specifically, the devices and methods relate to left ventricular capture using VfA cardiac therapy.

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

[0004] Patients with conduction system abnormalities, such as AV node 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 synchrony. Some types of IMDs, such as pacemakers, implantable cardioverter-defibrillators (ICDs), or cardiac resynchronization therapy (CRT) devices, provide therapeutic electrical stimulation to the patient's heart via one or more electrodes on implanted endocardial, epicardial, or coronary venous leads located in or near the heart. Therapeutic electrical stimulation can be delivered to the heart in the form of pulses or shocks for pacing, cardioversion, or defibrillation. In some cases, the IMD can sense intrinsic depolarization of the heart and control the delivery of therapeutic stimulation to the heart based on this sensing.

[0005] Delivering therapeutic electrical stimulation to the heart can help address cardiac conditions, such as ventricular dyssynchrony, which may occur in a patient. Ventricular dyssynchrony can be described as a lack of synchrony or a difference in the timing of contraction of the left and right ventricles of the heart. Significant differences in the timing of contraction can reduce the efficiency of the heart. CRT delivered to the heart by an IMD can enhance cardiac output by resynchronizing the electromechanical activity of the heart's ventricles. CRT may include "three-chamber pacing" when pacing the right atrium, right ventricle, and left ventricle.

[0006] In addition to cardiac pacing, arrhythmias may be treated by delivering shock therapy for cardioversion or defibrillation, such as by an ICD that senses the patient's heart rhythm and classifies the rhythm according to an arrhythmia detection scheme to detect episodes of tachycardia or fibrillation. Detected arrhythmias may include ventricular tachycardia (VT), rapid ventricular tachycardia (FVT), ventricular fibrillation (VF), atrial tachycardia (AT), and atrial fibrillation (AT). Antitachycardia pacing (ATP) may be used to treat ventricular tachycardia (VT), thereby substantially terminating many monomorphic rapid rhythms.

[0007] A dual chamber medical device may be used that includes a transvenous atrial lead that carries an electrode that can be placed in the right atrium and a transvenous ventricular lead that carries an electrode 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 into the subcutaneous pocket. The dual chamber medical device can sense atrial and ventricular electrical signals, and can provide atrial pacing and ventricular pacing as needed to promote normal heart rhythm and AV synchronization. Some dual chamber medical devices can treat atrial and ventricular arrhythmias.

[0008] Intracardiac medical devices, such as leadless pacemakers, have been introduced or proposed to be implanted completely within the patient's heart, thereby eliminating the need for transvenous leads. The housing of the leadless pacemaker may include one or more electrodes to deliver therapeutic electrical signals and / or sense intrinsic depolarization of the heart. Intracardiac medical devices can provide cardiac therapeutic functions, such as sensing and pacing, within a single chamber of the patient's heart. Single-chamber intracardiac devices can also treat atrial or ventricular arrhythmias or fibrillation. Some leadless pacemakers are not intracardiac and can be positioned outside the heart, and in some instances, can be secured to the wall of the heart via a securing mechanism.

[0009] In some patients, a single chamber device may adequately address 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., patients 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] The disclosed techniques, methods and processes generally relate to implantable medical devices, systems and methods for atrium-to-ventricle (VfA) cardiac resynchronization therapy (CRT). In addition, the disclosed techniques, methods and processes can be applied or used with cardiac therapies, including single-chamber or multi-chamber pacing (e.g., dual-chamber or triple-chamber pacing), atrioventricular synchronous pacing, asynchronous pacing, triggered pacing or tachycardia-related therapy.

[0011] The VfA device can be implanted in the right atrium (RA) and a tissue piercing electrode can be extended from the right atrium to the left ventricular myocardium. The tissue piercing electrode can be used to deliver pacing therapy to the left ventricle for various cardiac therapies. In order to determine whether pacing has captured the left ventricle and / or whether pacing is effective, electrical activity can be measured according to the left ventricular beat, or other physiological response measurements can be performed. Electrical activity and other physiological response measurements can be evaluated (e.g., compared to various thresholds, etc.) to determine whether pacing therapy has effectively captured the left ventricle.

[0012] Additionally, if it is determined that ventricular pacing therapy is ineffective or has not captured the left ventricle, the ventricular pacing therapy can be adjusted until the ventricular pacing therapy effectively captures the left ventricle. For example, one or more pacing settings can be adjusted or modified, and electrical activity or other physiological information can be monitored. The monitored electrical activity or other physiological information can be evaluated again to determine whether the ventricular pacing therapy has now effectively captured the left ventricle. For example, the atrioventricular (AV) pacing delay can be adjusted until left ventricular capture is determined. Advantageously, in one or more embodiments, the techniques of the present disclosure can be used to calibrate or deliver a more optimal pacing therapy without the use of monitored electrical activity of the right ventricle of the patient's heart.

[0013] In other words, the present disclosure describes a method for monitoring ventricular capture effectiveness and modifying one or more treatment parameters in the presence of a leadless VfA pacemaker device that is implanted in the AV septal region and has electrodes that can sense / pacing the atria and ventricles (particularly the left ventricle) for resynchronization pacing.

[0014] An illustrative implantable medical device may include a plurality of electrodes. The plurality of electrodes may include a tissue puncture electrode and a right atrial electrode, the tissue puncture electrode being implantable from the Koch triangle of the right atrium through the right atrial endothelium and the central fibrous body to deliver cardiac therapy to the left ventricle located at the base and / or septal region of the left ventricular myocardium of the patient's heart or sensing its electrical activity, and the right atrial electrode being positioned in the right atrium to deliver cardiac therapy to the right atrium of the patient's heart or sensing its electrical activity. The illustrative implantable medical device may further include: a therapy delivery circuit operably coupled to the plurality of electrodes to deliver cardiac therapy to the patient's heart; a sensing circuit operably coupled to the plurality of electrodes to sense the electrical activity of the patient's heart; and a controller comprising a processing circuit system operably coupled to the therapy delivery circuit and the sensing circuit. The controller may be configured to monitor left ventricular capture effectiveness. Monitoring left ventricular capture effectiveness may include delivering a left ventricular beat using the tissue piercing electrode, monitoring electrical activity of the left ventricle following the left ventricular beat using the tissue piercing electrode, and determining left ventricular tissue capture effectiveness of the left ventricular beat based on the monitored electrical activity.

[0015] An illustrative method may include providing a tissue-penetrating electrode implanted from the Koch triangle of the right atrium through the right atrial endocardium and the central fibrous body to deliver cardiac therapy or sense electrical activity to the left ventricle located at the base and / or septal region of the left ventricle of the patient's heart; providing a right atrial electrode positionable within the right atrium to deliver cardiac therapy or sense electrical activity to the right atrium of the patient's heart. The illustrative method may further include: delivering a left ventricular beat using the tissue-penetrating electrode; following the left ventricular beat, monitoring the electrical activity of the left ventricle using the tissue-penetrating electrode; and determining the effectiveness of left ventricular tissue capture of the left ventricular beat based on the monitored electrical activity.

[0016] An illustrative implantable medical device may include a plurality of electrodes, including at least one tissue piercing electrode and a right atrium electrode, wherein the tissue piercing electrode may be implanted from the Koch triangle of the right atrium through the right atrial endocardium and the central fibrous body to deliver cardiac therapy to the left ventricle located at the base and / or septal region of the left ventricle of the patient's heart or sense its electrical activity, and the right atrium electrode may be positioned in the right atrium to deliver cardiac therapy to the right atrium of the patient's heart or sense its electrical activity. The illustrative implantable medical device may further include: a therapy delivery circuit operably coupled to the plurality of electrodes to deliver cardiac therapy to the patient's heart; a sensing circuit operably coupled to the plurality of electrodes to sense the electrical activity of the patient's heart; and a controller including a processing circuit system operably coupled to the therapy delivery circuit and the sensing circuit. The controller may be further configured to perform left ventricular pulsation therapy using the tissue piercing electrode, monitor left ventricular capture effectiveness over a plurality of cardiac cycles based on electrical activity monitored using at least the tissue piercing electrode, determine that effective left ventricular capture is not occurring based on the monitoring of left ventricular capture effectiveness over a plurality of cardiac cycles, and adjust left ventricular pacing in response to determining that effective left ventricular capture is not occurring.

[0017] An exemplary VfA device is a leadless pacing / sensing device for delivering AV-synchronized ventricular sensing therapy. The device can be implanted in the AV septal region and has a sensing / pacing cathode in the atrium (e.g., an atrial cathode), a sensing / pacing cathode in the ventricle (e.g., a ventricular cathode), and a third electrode that serves as a common anode. During delivery of ventricular pacing from such a device, the effectiveness of therapy can be monitored by analyzing the morphological features of the near-field pacing electrogram (e.g., from the ventricular cathode to the atrial anode) based on the following criteria: (1) the absolute amplitude of the electrogram baseline < a threshold in millivolts; (2) the minimum negative deviation within a certain time range after the pacing event is lower than a certain threshold in millivolts; and (3) the timing of the negative minimum measured relative to the timing of the pacing event is less than a certain interval in milliseconds. If all three of the above criteria are met, it can be determined that effective tissue capture has occurred, and thus a diagnosis of a specific ventricular beat and effective ventricular pacing can be provided for such a VfA device.

[0018] The exemplary device may also make continuous therapeutic adjustments based on indications of effective or ineffective pacing. For example, if pacing is ineffective for at least X of Y beats, the device may run a series of diagnostic tests to correct it. If in DDD(R) mode, the device may initiate a capture test to measure the capture threshold and reset the output based on a value above the capture threshold. If pacing continues to be ineffective for X of Y beats, the device may reduce the AV delay in some steps to pace and continue to monitor the effectiveness. The AV delay may have a lower limit (e.g., 60 milliseconds for intrinsic atrial sensing and 70 milliseconds for atrial pacing) beyond which it will not be further reduced. If in VVI(R) mode, and the device acquires at least X of Y ineffective paced beats and at least W of Y sensed beats, the heart rate may be increased and the capture effectiveness may be continued to be monitored. In VVI mode, the increment of the heart rate may be modified to a certain maximum rate (e.g., 130 beats per minute). If, in VVI mode, the device determines that there are at least X beats out of Y invalid paced beats but no sensed beats, a capture threshold test may be initiated to establish a capture threshold and reset the pacing output. The example device may continue to track the proportion of effective pacing and sound an alarm if effective pacing drops below a certain level.

[0019] The details of one or more aspects of the disclosure are set forth in the drawings and description below. Other features, objects, and advantages of the techniques described in the disclosure will be apparent from the description and drawings and from the claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1is a conceptual diagram of an illustrative cardiac treatment system for use with the illustrative methods of, for example, FIGS. 16-18 , the system including an intracardiac medical device implanted in a patient's heart and a separate medical device located outside the patient's heart.

[0021] Figure 2-4 is a conceptual diagram of an illustrative cardiac treatment system for use with the illustrative methods of, for example, FIGS. 16-18 , including a medical device including leads with electrodes implanted in a patient's heart.

[0022] Figure 5 yes Figure 1 A magnified conceptual illustration of an intracardiac medical device and the anatomy of a patient's heart.

[0023] Figure 6 is used with, for example Figure 1-4 Conceptual illustration of a patient's heart in a standard 17-segment view of the left ventricle showing various electrode implant locations for use with an exemplary system and device.

[0024] Figure 7 is used with, for example Figure 1-4 A perspective view of an intracardiac medical device having a distal fixation and electrode assembly including a distal housing-base electrode implemented as a ring electrode for use with illustrative systems and devices of the present invention.

[0025] Figure 8 can be encapsulated in e.g. Figure 1-4 A block diagram of illustrative circuitry within the housing of a medical device to provide the functions and treatments described herein.

[0026] Fig. 9 is used with, for example Figure 1-4 A perspective view of another illustrative intracardiac medical device for use with the illustrative systems and devices.

[0027] Fig.10 is used with, for example Figure 1-4 A flow chart of an illustrative method of using an atrial motion detector to detect atrial activity for use with an illustrative system and apparatus.

[0028] Fig.11 is used with, for example Figure 1-4 A flow chart of an illustrative system and apparatus for use with an illustrative method of detecting heart sounds to represent physiological response information.

[0029] Fig.12 is used with, for example Figure 1-4 A flow chart of an illustrative system and apparatus for use with an illustrative method of detecting bioimpedance to represent physiological response information.

[0030] Fig.13 is used with, for example Figure 1-5 A conceptual diagram of an illustrative method for monitoring left ventricular capture effectiveness for use with the illustrative systems and devices of 7-9.

[0031] Fig.14 is used with, for example Figure 1-5 A portion of a monitoring near-field electrogram for use with the illustrative systems and devices of 7-9 for determining left ventricular capture effectiveness.

[0032] Fig.15 is used with, for example Figure 1-5 Another conceptual diagram of an illustrative method for monitoring left ventricular capture effectiveness for use with the illustrative systems and devices of 7-9. DETAILED DESCRIPTION

[0033] The processes, methods and techniques of the present disclosure are generally related to implantable medical devices, systems and methods for atrial to ventricular (VfA) cardiac resynchronization therapy. In addition, the processes, methods and techniques of the present disclosure are generally related to other cardiac therapies, including single-chamber or multi-chamber pacing (e.g., dual-chamber or triple-chamber pacing), atrioventricular synchronous pacing, asynchronous pacing, triggered pacing, cardiac resynchronization pacing or tachycardia-related therapy. Although implantable medical devices such as pacemakers or ICDs are referenced herein, the methods and processes can be used with any medical device, system or method related to the patient's heart. Various other applications that benefit from the present disclosure will become apparent to those skilled in the art.

[0034] It may be advantageous to provide an implantable medical device without a transvenous lead (e.g., a leadless device). It may also be advantageous to provide an implantable medical device that can be used for various cardiac therapies, such as cardiac resynchronization pacing, single or multi-chamber pacing (e.g., dual or triple chamber pacing), atrioventricular synchronous pacing, asynchronous pacing, triggered pacing, or tachycardia related therapies. In addition, it may be advantageous to provide a system that can communicate with a separate medical device, for example, to provide triggered pacing or to provide shock therapy in certain tachycardia situations. Still further, it may be advantageous to configure the implantable medical device to provide adaptive pacing therapy using only an intracardiac device or in combination with one or more leads or a separate medical device.

[0035] The present disclosure provides an implantable medical device comprising a tissue puncture electrode and optionally a right atrial electrode and / or a right atrial motion detector. The implantable medical device can be a VfA device implanted from the right atrium into the left ventricular myocardium. For example, the implantable medical device can be used for adaptive cardiac therapy, which can adapt pacing delays based on one or more of measured heart rate, intrinsic AV conduction, etc. Physiological response measurements can be performed, and the VfA device can be configured to deliver cardiac therapy based on physiological response information. In particular, the VfA device can be configured to adapt pacing therapy based on different heart rates and / or intrinsic AV conduction, for example, by determining and delivering pacing therapy with optimal atrioventricular (AV) pacing delay. Advantageously, in one or more embodiments, the technology of the present disclosure can be used to calibrate or deliver pacing therapy without using the monitored electrical activity of the right ventricle of the patient's heart.

[0036] The tissue puncture electrode can be implanted from the Koch triangle of the right atrium through the right atrial endothelium and the central fibrous body into the base and / or septum region of the left ventricular myocardium of the patient's heart. In a leadless implantable medical device, the tissue puncture electrode can extend leadlessly from the distal region of the housing of the device, and the right atrial electrode can be leadlessly coupled to the housing (e.g., a portion thereof or located outside the housing). In one or more embodiments, a right atrial motion detector can be located within the implantable medical device. In an implantable medical device with leads, one or more electrodes can be coupled to the housing using implantable leads. 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 motion detector can be used to sense mechanical activity in one or more atria and / or ventricles of the patient's heart. In particular, the activity of the right atrium and left ventricle can be monitored, and optionally, the activity of the right ventricle can be monitored. 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 electric shock therapy. Electric shock therapy can be initiated by the implantable medical device. A separate medical device such as an extravascular ICD that can also be implanted can be operably connected to the implantable medical device and can deliver an electric shock in response to a trigger such as a signaling pulse (e.g., a triggered, signaling, or unique electrical pulse) provided by the device.

[0037] Figure 1-4 Examples of various cardiac therapy systems are shown that may be configured to be used with, for example, Figure 13-15 The method shown is used together to monitor left ventricular capture and perform pacing therapy. Although the present disclosure describes leadless and leaded implantable medical devices, reference is first made to Figure 1, which shows a conceptual diagram of a cardiac treatment system 2, which includes an intracardiac medical device 10 that can be configured for single-chamber or dual-chamber treatment and implanted in a patient's heart 8. In some embodiments, the 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). As used herein, "intracardiac" refers to a device that is configured to be completely implanted within a patient's heart to, for example, provide cardiac treatment. The device 10 shown is implanted in a target implantation area 4 of the right atrium (RA) of the patient's heart 8. The device 10 may include one or more fixtures 20 that anchor the distal end of the device to the atrial endothelium in the target implantation area 4. The target implantation area 4 can be located between the bundle of His 5 and the coronary sinus 3 and can be adjacent to the tricuspid valve 6. Device 10 may be described as an atrium-to-ventricle (VfA) device that is typically placed in the right atrium and may sense or provide therapy to one or both ventricles (e.g., the right ventricle, the left ventricle, or both ventricles, as appropriate). In particular, device 10 may include a tissue-penetrating electrode that may be implanted from the triangle of Koch of the right atrium through the right atrial endothelium and the central fibrous body into the basal and / or septal region of the left ventricular myocardium of the patient's heart.

[0038] The device 10 can be described as a leadless implantable medical device. As used herein, "leadless" refers to a device that does not have leads extending out of the patient's heart 8. In other words, a leadless device can have leads that do not extend from outside the patient's heart to inside the patient's heart. Some leadless devices can be introduced intravenously, 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, particularly when the housing of the device is located in the atrium, the leadless VfA device can be operably connected to electrodes in the ventricle without the use of leads. 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.

[0039] The device 10 may include a dart electrode assembly 12 that defines or has a straight axis extending from a distal region of the device 10. The dart electrode assembly 12 may be placed or at least configured to be placed into the ventricular myocardium 14 through the atrial myocardium and the central fiber body, 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 region of the shaft so that the electrode can be positioned within the ventricular myocardium to sense ventricular signals and deliver ventricular pulses (e.g., depolarize the left ventricle to initiate left ventricular contraction). In some instances, the electrode at the distal region of the shaft is a cathode electrode used in a bipolar electrode pair for pacing and sensing. Although the implantation region 4 shown may enable one or more electrodes of the dart electrode assembly 12 to be positioned within the ventricular myocardium, it is recognized that devices having aspects disclosed herein may be implanted in other locations for multi-chamber pacing (e.g., dual-chamber or triple-chamber pacing), single-chamber pacing with multi-chamber sensing, single-chamber pacing and / or sensing, or other appropriate 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 into the ventricular myocardium 14 or along the ventricular septum through the atrial myocardium and the central fiber body without completely penetrating the ventricular endocardial or epicardial surface. In addition, each dart electrode assembly may carry or include more than one single electrode at the distal region of the shaft or at other regions along the shaft (e.g., the proximal or central region).

[0041] The cardiac treatment system 2 may also include a separate medical device 50 (in Figure 1 ), which 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. In one instance, the separate medical device 50 can be an extravascular ICD. In some embodiments, the extravascular ICD may include a defibrillation lead that includes or carries a defibrillation electrode. The treatment vector may exist between the defibrillation electrode on the defibrillation lead and the housing electrode of the ICD. In addition, 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 an arrhythmia is sensed, the ICD can send pulses via electrical leads to shock the heart and restore its normal rhythm. In some instances, 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. Pat. No. 9,278,229 (Reinke et al.), issued Mar. 8, 2016, which is incorporated herein by reference in its entirety.

[0042] In the case of 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 the following waveform characteristics: 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 about 60-80 joules (J) of energy for subcutaneous defibrillation.

[0043] The individual medical device 50 may further include a sensing circuit. The sensing circuit may be configured to obtain electrical signals sensed via one or more combinations of electrodes, and process the obtained signals. 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 sensing 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 the 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 the 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 tachycardia, monitor tachycardia, and / or provide tachycardia-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 operable 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, signaling, or triggering 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] Reference Figure 2, the leaded medical device 408 includes one or a single implantable lead 410 having a tissue piercing electrode assembly 12 coupled to a distal region of the lead and implanted within the patient's heart 8. The housing 420 of the leaded medical device 408 can be implanted and positioned outside the patient's heart 8 and is configured to calibrate pacing therapy and / or deliver pacing therapy, for example, based at least on a measured heart rate. The lead 410 can include a right atrial electrode, and the device 408 can be used as a device with dual-channel capabilities (e.g., pacing and / or sensing in the right atrium and left ventricle). In some embodiments, the lead 410 may not include a right atrial electrode. In other words, the leaded medical device 408 can be a single-channel device that can be used for asynchronous, triggered, or other types of single-channel pacing. When the tissue piercing electrode assembly 12 is implanted, for example, in conjunction with Figure 1 In the same or similar manner, leaded medical device 408 using lead 410 can sense activity or deliver pacing to the left ventricle (LV).

[0046] Reference Figure 3 , a leaded medical device 418 similar to Figure 2 408, but device 418 includes two implantable leads 410, 412. In particular, implantable lead 412 may include an electrode coupled to a distal region of lead 412 (e.g., a right atrium electrode) and may be implanted at a different location than lead 410. In some embodiments, lead 412 is implanted in a different region of the right atrium. In some embodiments, each lead 410, 412 may constitute one channel of dual channel device 418. For example, when implanting a tissue piercing electrode of tissue piercing electrode assembly 12, for example, in conjunction with and Figure 1 In the same or similar manner as described, lead 410 can sense activity or deliver pacing to the left ventricle (LV), and lead 412 can sense activity or deliver pacing to the right atrium (RA).

[0047] Reference Figure 4 , a leaded medical device 428 similar to Figure 3 The leaded medical device 418 of FIG. 4 is shown in FIG. 4 , but the device 428 includes three implantable leads 410, 412, 414. In particular, the implantable lead 414 may include an electrode (e.g., a right ventricle electrode) coupled to a distal region of the lead 414 and may be implanted at a different location than the leads 410, 412. In some embodiments, the lead 414 is implanted in the region of the right ventricle. In some embodiments, each lead 410, 412, 414 may constitute a channel of the multi-channel device 428. For example, when the tissue piercing electrode assembly 12 is implanted, for example, in conjunction with Figure 1In the same or similar manner, lead 410 can sense activity or deliver pacing to the left ventricle (LV), lead 412 can sense activity and deliver pacing to the right atrium (RA), and lead 414 can sense activity and deliver pacing to the right ventricle (RV).

[0048] In some embodiments, a pacing delay (e.g., RV-LV pacing delay or, more generally, VV pacing delay) between an RV electrode on lead 414 for pacing the RV and an LV electrode on lead 410 for pacing the LV can be calibrated or optimized, for example, using a separate medical device such as an electrode device (e.g., an ECG belt). Various methods can be used to calibrate or optimize the VV delay. In some embodiments, the medical device 428 can be used to test pacing with multiple different VV delays. For example, the RV can be paced approximately 80, 60, 40, and 20 milliseconds (ms) ahead of the LV, the LV can also be paced approximately 80, 60, 40, and 20 ms ahead of the RV, or the RV-LV can be paced simultaneously (e.g., a VV pacing delay of approximately 0 ms). The medical device 428 can then, for example, be automatically configured to select a VV pacing delay that corresponds to the minimum electrical dyssynchrony measured using the electrode device when used for pacing. Pacing testing at different VV pacing delays may be performed using a specific AV delay (eg, a nominal AV delay set by medical device 428) or a predetermined optimal AV delay based on patient characteristics.

[0049] Figure 5 yes Figure 1 1 and an enlarged conceptual diagram of an intracardiac medical device 10 and the anatomy of a patient's heart 8. In particular, the device 10 is configured to perform pacing therapy and / or deliver pacing therapy, for example, based at least on a measured heart rate. The intracardiac device 10 may include a housing 30. The housing 30 may define an airtight interior cavity within which the internal components of the device 10 are located, such as in combination with Figure 8 The housing 30 may be formed of a conductive material including titanium or a titanium alloy, stainless steel, MP35N (non-magnetic nickel-cobalt-chromium-molybdenum alloy), a platinum alloy, or other biocompatible metal or metal alloy. In other examples, the housing 30 may be formed of a non-conductive material including ceramic, glass, sapphire, silicone, polyurethane, epoxy, acetyl copolymer plastic, polyetheretherketone (PEEK), liquid crystal polymer, or other biocompatible polymer.

[0050] In at least one embodiment, the housing 30 can be described as extending between a distal region 32 and a proximal region 34 in a generally cylindrical shape to facilitate catheter delivery. In other embodiments, the housing 30 can be prismatic or any other shape to perform the functions and uses described herein. The housing 30, for example at the proximal region 34, can include a delivery tool interface member 26 for engaging with a delivery tool during implantation of the device 10.

[0051] All or a portion of the housing 30 may be used as an electrode during cardiac therapy, for example, in sensing and / or pacing. In the illustrated example, the housing-based electrode 24 is shown as being externally attached to a proximal portion of the housing 30 (e.g., closer to the proximal region 34 than the distal region 32). When the housing 30 is formed of a conductive material (such as a titanium alloy or other examples listed above), a portion of the housing 30 may be electrically insulated by a non-conductive material (such as a coating of parylene, polyurethane, silicone, epoxy, or other biocompatible polymers) such that one or more discrete areas of conductive material are exposed to define the proximal housing-based electrode 24. When the housing 30 is formed of a non-conductive material such as a ceramic, glass, or polymer material, 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 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. When the housing 30 is a non-conductive material, the proximal housing-based electrodes 24 may be electrically coupled to the internal circuitry of the device 10 , for example, via the conductive housing 30 or electrical conductors.

[0052] In the illustrated example, the proximal housing-based electrode 24 is closer to the housing proximal region 34 relative to the housing distal region 32, and is therefore referred to as a "proximal housing-based electrode" 24. However, in other examples, the housing-based electrode 24 can be located at other locations along the housing 30, for example, farther away from the illustrated location.

[0053] At the distal region 32, the device 10 may include a distal fixation and electrode assembly 36, which may include one or more fixation members 20 of equal or unequal lengths and one or more dart electrode assemblies 12. In one example, a single dart electrode assembly 12 includes a shaft 40 extending distally from the housing distal region 32 and one or more electrode elements, such as a tip electrode 42 located at or near the free distal region of the shaft 40. The tip electrode 42 may have a conical or hemispherical distal tip with a relatively narrow tip diameter (e.g., less than about 1 millimeter (mm)) for penetrating and passing through tissue layers without the use of a sharp tip or needle tip with a sharpened or beveled edge.

[0054] The shaft 40 of the dart electrode assembly 12 can be a generally straight member and can be rigid. In other embodiments, the shaft 40 can be described as relatively stiff, but still having limited flexibility in the lateral direction. In addition, the shaft 40 can be non-rigid to allow for some lateral flexure with heart movement. However, in a relaxed state, when not subjected to any external forces, the shaft 40 can remain in a straight position as shown to space the tip electrode 42 from the housing distal region 32 by at least the height 47 of the shaft 40. In other words, the dart electrode assembly 12 can be described as elastic.

[0055] The dart electrode assembly 12 can be configured to puncture one or more tissue layers to position the tip electrode 42 within a desired tissue layer, such as within the ventricular myocardium. In this way, the height 47 or length 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 the lateral or radial direction when pressed toward 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 can be configured to be used as an indifferent electrode for delivering pacing energy to the tissue. A longitudinal axial force can be applied to the tip electrode 42, for example, by applying a longitudinal thrust to the proximal end 34 of the housing 30, to advance the dart electrode assembly 12 into the tissue within the target implantation area. When subjected to a lateral or radial force, the shaft 40 can be described as longitudinally non-compressible and / or elastically deformable in the lateral or radial direction to allow, for example, temporary flexure accompanying tissue movement, but can return to its generally straight position when the lateral force is reduced. When the shaft 40 is not subjected to any external forces or is subjected only to forces along its longitudinal center axis, the shaft 40 may maintain a straight linear position, as shown.

[0056] One or more fixation members 20 can be described as one or more "tines" having a normal curved position. The tines can be located in a distally extending position within the delivery tool. When released from the delivery tool, the distal tips of the tines can penetrate the cardiac tissue to a limited depth before elastically bending proximally back to the normal curved position (shown). In addition, the fixation member 20 can include, for example, one or more aspects described in U.S. Pat. No. 9,675,579 (Grubac et al.), issued on June 13, 2017, and U.S. Pat. No. 9,119,959 (Rys et al.), issued on September 1, 2015, the entire contents of which are incorporated herein by reference in their entirety.

[0057] In some examples, the distal fixation and electrode assembly 36 includes a distal housing-based electrode 22. In the case of using the device 10 as a pacemaker for multi-chamber pacing (e.g., dual-chamber or triple-chamber pacing) and sensing, the tip electrode 42 can be used as a cathode electrode that is paired with the proximal housing-based electrode 24 used as a return anode electrode. Alternatively, the distal housing-based electrode 22 can be used as a return anode electrode paired with the tip electrode 42 to sense ventricular signals and deliver ventricular pacing pulses. In other examples, the distal housing-based electrode 22 can be a cathode electrode for sensing atrial signals and delivering pacing pulses to the atrial myocardium in the target implant area 4. When the distal housing-based electrode 22 is used as an atrial cathode electrode, the proximal housing-based electrode 24 can be used as a return anode paired with the tip electrode 42 for ventricular pacing and sensing, and can be used as a return anode paired with the distal housing-based electrode 22 for atrial pacing and sensing.

[0058] As shown in this figure, in some pacing applications, the target implantation area 4 is along the atrial endothelium 18, generally inferior to the AV node 15 and the bundle of His 5. The dart electrode assembly 12 can at least partially define the height 47 or length of the shaft 40 to pass through the atrial endothelium 18 in the target implantation area 4 and through the central fiber body 16 into the ventricular myocardium 14 without passing through the ventricular endothelium surface 17. When the height 47 or length of the dart electrode assembly 12 is fully advanced into the target implantation area 4, the tip electrode 42 can be placed in the ventricular myocardium 14, and the electrode 22 based on the distal housing can be in close contact with or close to the atrial endothelium 18. In various examples, the dart electrode assembly 12 can have a total combined height 47 or length of the tip electrode 42 and the shaft 40 of about 3 mm to about 8 mm. The diameter of the shaft 40 can be less than about 2 mm, and can be about 1 mm or less, or even about 0.6 mm or less.

[0059] The device 10 may include an acoustic or motion detector 11 located within the housing 30. The acoustic or motion detector 11 may be operably coupled to one or more control circuits 80 ( Figure 8 )、Sensing circuit 86( Figure 8 ) or therapy delivery circuit 84 ( Figure 8 In some embodiments, the acoustic or motion detector 11 may be coupled to Figure 10-12The acoustic or motion detector 11 can be used in conjunction with the method 600, 650, or 800 shown. The acoustic 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 or motion detector 11 can be used to detect right atrial mechanical activity. Non-limiting examples of the acoustic or motion detector 11 include an accelerometer or a microphone. In some embodiments, the mechanical activity detected by the acoustic or motion detector 11 can be used to supplement or replace the electrical activity detected by one or more electrodes of the device 10. For example, the acoustic or motion detector 11 can be used with or as a substitute for the electrodes 24 based on the proximal housing.

[0060] Acoustic or motion detector 11 may also be used for rate responsiveness detection or providing rate responsive IMD. Various techniques related to rate responsiveness may be described in U.S. Pat. No. 5,154,170 (Bennett et al.), issued Oct. 13, 1992, entitled "Optimization for rate responsive cardiac pacemaker," and U.S. Pat. No. 5,562,711 (Yerich et al.), issued Oct. 8, 1996, entitled "Method and apparatus for rate-responsive cardiac pacing," both of which are incorporated herein by reference in their entirety.

[0061] In various embodiments, the acoustic or motion sensor 11 can be used as a HS sensor and can be implemented as a microphone or a 1-axis, 2-axis, or 3-axis accelerometer. In one embodiment, the acoustic sensor is implemented as a piezoelectric crystal that is mounted within the implantable medical device housing and responds to mechanical movement associated with heart sounds. The piezoelectric crystal can be a dedicated HS sensor or can be used for multiple functions. In the illustrative embodiment shown, the acoustic sensor is implemented as a piezoelectric crystal that is also used to generate a patient alarm signal in the form of a perceptible vibration of the IMD housing. When an alarm condition is detected, the control circuit 80 can cause the patient alarm control circuit system to generate an alarm signal by activating the piezoelectric crystal.

[0062] The control circuitry can be used to control whether the piezoelectric crystal is used in a "listen mode" to sense HS signals through the HS sensing circuitry, or in an "output mode" to generate a patient alarm. During the generation of a patient alarm, the HS sensing circuitry can be temporarily decoupled from the HS sensor by the control circuitry.

[0063] Examples of other embodiments of acoustic sensors that may be implemented with the presently disclosed technology may be generally described in U.S. Pat. No. 4,546,777 (Groch et al.), U.S. Pat. No. 6,869,404 (Schulhauser et al.), U.S. Pat. No. 5,554,177 (Kieval et al.), and U.S. Pat. No. 7,035,684 (Lee et al.), each of which is incorporated herein by reference in its entirety.

[0064] Various types of acoustic sensors may be used. The acoustic sensor may be any implantable or external sensor that responds to one or more heart sounds generated as previously described, thereby generating an electrical analog signal that is related in time and amplitude to the heart sound. The HS sensing module may then process the analog signal, which processing 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 sensor and HS sensing module may be incorporated into an IMD capable of delivering CRT or other cardiac therapy being optimized, or may be implemented in a separate device that communicates wired or wirelessly with the IMD, or in an external programmer or computer used in a pulsating parameter optimization process as described herein.

[0065] Figure 6 300 (e.g., a top view) of a patient's heart, showing a left ventricle 320 in a standard 17-segment view, and showing a right ventricle 322. The map 300 includes a plurality of regions 326 corresponding to different regions of a human heart. As shown, the regions 326 are numerically labeled 1-17 (e.g., corresponding to a standard 17-segment model of a human heart, corresponding to 17 segments of a left ventricle of a human heart, etc.). The regions 326 of the map 300 may include a basal anterior region 1, a basal anterior septal region 2, a basal inferior septal region 3, a basal inferior region 4, a basal inferior lateral region 5, a basal anterolateral region 6, a mid-anterior region 7, an anterior septal middle region 8, an inferior septal middle region 9, a lower middle region 10, a lower lateral middle region 11, an anterolateral middle region 12, an apical anterior region 13, an apical septal region 14, an apical inferior region 15, an apical region 16, and an apex region 17. Also shown are the infraseptal and anteroseptal regions of the right ventricle 322, as well as the right bundle branch (RBB) and left bundle branch (LBB).

[0066] In some embodiments, any tissue piercing electrode of the present disclosure can be implanted into the basal and / or septal region of the left ventricular myocardium of the patient's heart. In particular, the tissue piercing electrode can be implanted from the Koch triangle of the right atrium through the right atrial endocardium and the central fibrous body.

[0067] Once implanted, the tissue piercing electrode can be positioned at the target implantation area 4 ( Figure 1-5), such as the basal and / or septal regions of the left ventricular myocardium. Referring to FIG300, the basal region includes one or more of the basal anterior region 1, the basal anterior septal region 2, the basal inferior septal region 3, the basal inferior region 4, the mid-anterior region 7, the anterior septal middle region 8, the inferior septal middle region 9, and the inferior middle region 10. Referring to FIG300, the septal region includes one or more of the basal anterior septal region 2, the basal anterior septal region 3, the anterior septal middle region 8, the inferior septal middle region 9, and the apical septal region 14.

[0068] In some embodiments, when implanted, the tissue puncture electrode can be positioned in the basal septal region of the left ventricular myocardium. The basal septal region can include one or more of the basal anterior septal region 2, the basal inferior septal region 3, the anterior septal mid region 8, and the inferior septal mid region 9.

[0069] In some embodiments, when implanted, the tissue puncture electrode can be positioned in the superior inferior / posterior basal septum region of the left ventricular myocardium. The superior inferior / posterior basal septum region of the left ventricular myocardium may include a portion of one or more of the basal inferior septum region 3 and the inferior septal middle region 9 (e.g., only the basal inferior septum region, only the inferior septal middle region, or both the basal inferior septum region and the inferior septal middle region). For example, the superior inferior / posterior basal septum region may include an area 324 generally shown as a dashed line boundary. As shown, the dashed line boundary represents an approximation of the location of the superior inferior / posterior basal septum region, and its shape or size may vary depending on the specific application.

[0070] Figure 7 3D is a stereogram of a device 10 that can, for example, calibrate pacing therapy and / or deliver pacing therapy based on at least a measured heart rate. As shown, a distal fixation and electrode assembly 36 includes an electrode 22 based on a distal housing that is implemented as a ring electrode. When the fixing member tines 20a, 20b, and 20c of the fixing member 20 engage with the atrial tissue, the electrode 22 based on the distal housing can be in close contact with the atrial tissue or can be positioned adjacent to the atrial tissue. The tines 20a, 20b, and 20c that can be elastically deformed 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 puncture the atrial endocardial surface, and when no longer constrained in the delivery tool, they bend back to their normal bending position (as shown). When the tines 20a, 20b, and 20c bend back to their normal position, the fixing member 20 can pull the distal fixing member and electrode assembly 36 toward the atrial endocardial surface. As the distal fixation member and electrode assembly 36 are pulled toward the atrial endocardium, the tip electrode 42 can be advanced through the atrial myocardium and central fibrous body and into the ventricular myocardium. The distal housing-based electrode 22 can then be positioned against the atrial endocardial surface.

[0071] The distal housing-based electrode 22 may include a ring formed of a conductive material, such as titanium, platinum, iridium, or alloys thereof. The distal housing-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 other 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 housing-based electrode 22. Reducing the conductive surface area of ​​the distal housing-based electrode 22, such as by covering a portion of the conductive ring with an insulating coating, may increase the electrical impedance of the distal housing-based electrode 22, thereby reducing the current delivered during a pacing pulse that captures myocardium (e.g., atrial myocardial tissue). Less current consumption may save a power source for the device 10, such as one or more rechargeable or non-rechargeable batteries.

[0072] As described above, the distal housing-based electrode 22 can be configured as an atrial cathode electrode for delivering pacing pulses to atrial tissue at the implant site in combination with the proximal housing-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 the sensed P waves) and for controlling atrial synchronized ventricular pacing pulses delivered using the tip electrode 42 as a cathode and the proximal housing-based electrode 24 as a return anode. In other examples, the distal housing-based electrode 22 can be used as a return anode in conjunction with the cathode tip electrode 42 for ventricular pacing and sensing.

[0073] Figure 8 is a block diagram of a circuit system, which according to one example may be enclosed in a housing 30 ( Figure 7 ) to implement the functionality of calibrating pacing therapy and / or delivering pacing therapy using device 10 (e.g., based at least on the measured heart rate) or enclosed in any other medical device described herein (e.g., Figure 2 Device 408, Figure 3 Device 418, Figure 4 Device 428 or Fig. 9 The medical device 50 ( Figure 1-4) may include some or all of the same components, which may be configured in a similar manner. The electronic circuit system enclosed in the housing 30 may include software, firmware, and hardware that collaboratively monitor atrial and ventricular electrocardiographic signals, determine when cardiac therapy is needed, and / or deliver electrical pulses to the patient's heart according to programmed treatment 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 treatment delivery circuit 84, a sensing circuit 86, and / or a telemetry circuit 88. In some instances, the device 10 includes one or more sensors 90 for generating signals related to a patient's physiological function, state, or condition, such as a patient activity sensor, for determining whether pacing therapy is needed and / or controlling the pacing rate. For example, a sensor 90 may include an inertial measurement unit (e.g., an accelerometer) to measure motion.

[0074] The power supply 98 can provide power to the circuit system of the device 10 including each component 80, 82, 84, 86, 88, 90 as needed. The power supply 98 can include one or more energy storage devices, such as one or more rechargeable or non-rechargeable batteries. A person of ordinary skill in the art can understand the connection between the power supply 98 and each component 80, 82, 84, 86, 88, 90 through the general block diagram shown (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 the holding capacitor included in the therapy delivery circuit 84, which is controlled by the control circuit 80 to discharge at the appropriate time, so as to deliver pacing pulses according to a dual chamber pacing mode such as DDI (R). The power supply 98 can also be coupled to components of the sensing circuit 86 (e.g., sensing amplifiers, analog-to-digital converters, switching circuit systems, etc.), sensors 90, telemetry circuits 88, and memory 82 to provide power to various circuits.

[0075] The functional blocks shown represent the functions included in the device 10 and may include any discrete and / or integrated electronic circuit components that implement analog and / or digital circuits capable of producing the functions of the medical device 10 herein. The various components may include processing circuit systems, such as application specific integrated circuits (ASICs) that execute one or more software or firmware programs, electronic circuits, processors (shared, dedicated, or groups) and memories, 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 treatment delivery methods employed by the medical device.

[0076] 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, memory 82 may include a non-transitory computer-readable medium storing instructions that, when executed by one or more processing circuits, cause control circuit 80 and / or other processing circuit systems to calibrate pacing therapy and / or perform single-chamber, dual-chamber, or triple-chamber calibrated pacing therapy (e.g., single-chamber or multi-chamber pacing), or other cardiac therapy functions performed by device 10 (e.g., sensing or delivering therapy). The non-transitory computer-readable medium storing instructions may include any of the media listed above.

[0077] 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 events (e.g., P waves and R waves, or the absence of P waves and R waves). The tip electrode 42, the distal housing-based electrode 22, and the proximal housing-based electrode 24 can be electrically coupled to the therapy delivery circuit 84 to deliver electrical stimulation pulses to the patient's heart and the sensing circuit 86, and for sensing cardiac electrical signals.

[0078] The sensing circuit 86 may include an atrial (A) sensing channel 87 and a ventricular (V) sensing channel 89. The distal shell-based electrode 22 and the proximal shell-based electrode 24 may be coupled to the atrial sensing channel 87 to sense atrial signals, such as a P wave accompanying atrial myocardial depolarization. In instances including two or more optional distal shell-based electrodes, the sensing circuit 86 may include a switching circuit system for selectively coupling one or more available distal shell-based electrodes to the cardiac event detection circuit system included in the atrial sensing channel 87. The switching circuit system may include a switch array, a switch matrix, a multiplexer, or any other type of switching device suitable for selectively coupling components of the sensing circuit 86 to selected electrodes. The tip electrode 42 and the proximal shell-based electrode 24 may be coupled to the ventricular sensing channel 89 to sense ventricular signals, such as an R wave accompanying atrial myocardial depolarization.

[0079] Each of the atrial sensing channel 87 and the ventricular sensing channel 89 may include a cardiac event detection circuit system for detecting P waves and R waves, respectively, from the cardiac electrical signals received by the respective sensing channels. The cardiac event detection circuit system included in each channel 87 and 89 may be configured to amplify, filter, digitize and rectify the cardiac electrical signals received from the selected electrodes to improve the signal quality for detecting cardiac electrical events. The cardiac event detection circuit system within each channel 87 and 89 may include one or more sense amplifiers, filters, rectifiers, threshold detectors, comparators, analog-to-digital converters (ADCs), timers, or other analog or digital components. The cardiac event sensing thresholds, such as the P wave sensing threshold and the R wave sensing threshold, may be automatically adjusted by the respective sensing channels 87 and 89 under the control of the control circuit 80 (e.g., based on the timing interval and the sensing threshold determined by the control circuit 80), stored in the memory 82, and / or controlled by the hardware, firmware, and / or software of the control circuit 80 and / or the sensing circuit 86.

[0080] 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 atrial sensing channel 87 may generate a P-wave sensed event signal in response to a P-wave sensing threshold crossing. The ventricular sensing channel 89 may 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. Depending on the particular programmed pacing mode, the sensed event signal may trigger or inhibit a pacing pulse. For example, a P-wave sensed event signal received from the atrial sensing channel 87 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 detected before the AV pacing interval ends, a ventricular pacing pulse may be inhibited. If the AV pacing interval terminates before control circuit 80 receives an R-wave sense event signal from ventricular sensing channel 89, control circuit 80 may use therapy delivery circuit 84 to deliver a predetermined ventricular pacing pulse synchronized with the sensed P-wave.

[0081] In some instances, the device 10 can be configured to deliver various pacing therapies, including bradycardia pacing, cardiac resynchronization therapy, post-shock pacing, and / or tachycardia-related therapies, such as ATP. For example, the device 10 can be configured to detect non-sinus tachycardia and deliver ATP. The control circuit 80 can determine cardiac event time intervals, such as the PP interval between consecutive P wave sensing event signals received from the atrial sensing channel 87, the RR interval between consecutive R wave sensing event signals received from the ventricular sensing channel 89, and the PR and / or RP intervals received between the P wave sensing event signals and the R wave sensing event signals. These intervals can be compared to the tachycardia detection interval to detect non-sinus tachycardia. Tachycardia can be detected in a given cardiac chamber based on a threshold number of tachycardia detection intervals detected.

[0082] The therapy delivery circuit 84 may include an atrial pacing circuit 83 and a ventricular pacing circuit 85. Each pacing circuit 83, 85 may include charging circuitry, one or more charge storage devices (e.g., one or more low voltage holding capacitors), an output capacitor, and / or switching circuitry that controls the delivery of pacing pulses to pacing electrode vectors coupled to the respective pacing circuit 83, 85 as the holding capacitor is charged and discharged across the output capacitor. The tip electrode 42 and the proximal housing-based electrode 24 may be coupled to the ventricular pacing circuit 85 as a bipolar cathode and anode pair to deliver ventricular pacing pulses, for example, at the end of an AV or VV pacing interval set by the control circuit 80, thereby providing atrial synchronized ventricular pacing and a substantially lower ventricular pacing rate.

[0083] The atrial pacing circuit 83 can be coupled to the distal housing-based electrode 22 and the proximal housing-based electrode 24 to deliver atrial pacing pulses. The control circuit 80 can set one or more atrial pacing intervals according to a programmed lower pacing rate, or can set a temporary lower rate according to a pacing rate indicated by a rate-responsive sensor. If the atrial pacing interval is terminated before a P-wave sense event signal is received from the atrial sensing channel 87, the atrial pacing circuit can be controlled to deliver an atrial pacing pulse. The control circuit 80 starts an AV pacing interval in response to the delivered atrial pacing pulse to provide synchronized multi-chamber pacing (e.g., dual-chamber or triple-chamber pacing).

[0084] The therapy delivery circuit 84 can charge a holding capacitor of the atrial or ventricular pacing circuit 83, 85 to a programmed pacing voltage amplitude and discharge the capacitor to a programmed pacing pulse width based on a control signal received from the control circuit 80. For example, a pacing timing circuit included in the control circuit 80 can include a programmable digital counter set by a microprocessor of the control circuit 80 to control a basic pacing time interval associated with various single-chamber or multi-chamber pacing (e.g., dual-chamber or triple-chamber pacing) modes or anti-tachycardia pacing sequences. The microprocessor of the control circuit 80 can also set the amplitude, pulse width, polarity or other characteristics of the cardiac pacing pulse based on programmed values ​​stored in the memory 82.

[0085] The device 10 may include other sensors 90 for sensing signals from the patient for determining the need for and / or controlling the electrical stimulation therapy delivered by the therapy delivery circuit 84. In some instances, the sensor indicating the need for an increase in cardiac output may include a patient activity sensor, such as an accelerometer. An increase in the patient's metabolic demand caused by an increase in activity indicated by the patient activity sensor may be determined by the control circuit 80 for determining a pacing rate indicated by the sensor. The control circuit 80 may be used to calibrate and / or deliver pacing therapy based on the patient activity sensor (e.g., a measured heart rate).

[0086] 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 via telemetry circuitry 88, which can also be described as a communication interface. The telemetry circuitry 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 circuitry 80 can use the telemetry circuitry 88 to receive downlink telemetry from the external device and to send uplink telemetry to the external device. In some cases, the telemetry circuitry 88 can be used to send and receive communication signals to / from another medical device implanted in the patient.

[0087] Fig. 9 7 is a three-dimensional stereoscopic view of another leadless intracardiac medical device 710 according to another example, which can be configured to calibrate pacing therapy and / or deliver pacing therapy, for example, based at least on a measured heart rate, for single-chamber or multi-chamber heart therapy (e.g., dual-chamber or triple-chamber heart therapy). The device 710 can include a housing 730 having an outer sidewall 735, shown as a cylindrical outer sidewall, extending from a housing distal region 732 to a housing proximal region 734. The housing 730 can enclose an electronic circuit system configured to perform single-chamber or multi-chamber heart therapy, including atrial and ventricular electrocardiographic signal sensing and pacing of the atria and ventricles. The delivery tool interface member 726 is shown located on the housing proximal region 734.

[0088] The distal fixation and electrode assembly 736 can be coupled to the housing distal region 732. The distal fixation and electrode assembly 736 can include an electrically insulating distal member 772 coupled to the housing distal region 732. The tissue piercing electrode assembly 712 extends away from the housing distal region 732, and the plurality of non-tissue piercing electrodes 722 can be directly coupled to the insulating distal member 772. The tissue piercing electrode assembly 712 extends longitudinally away from the housing distal region 732 and can be coaxial with the longitudinal center axis 731 of the housing 730.

[0089] The distal tissue piercing electrode assembly 712 may include an electrically insulated shaft 740 and a tip electrode 742 (e.g., a tissue piercing electrode). In some instances, the tissue piercing electrode assembly 712 is an active fixation member that includes a helical shaft 740 and a distal cathode tip electrode 742. The helical shaft 740 may extend from a shaft distal region 743 to a shaft proximal region 741, which may be directly coupled to an insulating distal member 772. The helical shaft 740 may be coated with an electrically insulating material, such as polyparaxylene or other examples listed herein, to avoid sensing or stimulating cardiac tissue along the length of the shaft. The tip electrode 742 is at the shaft distal region 743 and may be used as a cathode electrode for delivering ventricular pacing pulses and sensing ventricular electrical signals using a proximal housing-based electrode 724 as a return anode when the tip electrode 742 is advanced into the ventricular tissue. The proximal housing-based electrode 724 may be a ring electrode surrounding the housing 730 and may be defined by an uninsulated portion of a longitudinal sidewall 735. Other portions of the housing 730 that are not used as electrodes may be coated with an electrically insulating material, such as in the above combination. Figure 7 described.

[0090] The use of two or more tissue piercing electrodes (e.g., any type of piercing electrodes) penetrating the LV myocardium can provide for more localized pacing capture and can mitigate the impact of atrial tissue capture of ventricular pacing spikes. In some embodiments, the multiple tissue piercing electrodes may include two or more dart-type electrode assemblies (e.g., Figure 7 Non-limiting examples of multiple tissue piercing electrodes include two dart electrode assemblies, a helical electrode with a dart electrode assembly extending therethrough (e.g., through the center), or a double-wound helix. Multiple tissue piercing electrodes can also be used for bipolar or multipolar pacing.

[0091] In some embodiments, one or more tissue piercing electrodes (e.g., any type of piercing electrode) that penetrate the LV myocardium can be a multipolar tissue piercing electrode. A multipolar tissue piercing electrode can include one or more electroactive elements and an electro-isolation element, which can achieve bipolar or multipolar pacing using one or more tissue piercing electrodes.

[0092] A plurality of non-tissue piercing electrodes 722 may be disposed along the periphery of the insulating distal member 772 and located around the tissue piercing electrode assembly 712. The insulating distal member 772 may define a distal-facing surface 738 of the device 710 and a circumferential surface 739 located at the periphery of the device 710 adjacent to the longitudinal sidewall 735 of the housing. The non-tissue piercing electrodes 722 may be formed of a conductive material such as titanium, platinum, iridium, or alloys thereof. In the illustrated embodiment, six non-tissue piercing electrodes 722 are radially spaced at equal distances along the periphery of the insulating distal member 772, however, two or more non-tissue piercing electrodes 722 may be provided.

[0093] The non-tissue piercing electrodes 722 can be discrete components, each of which is held within a corresponding recess 774 in the insulating member 772, wherein the recess is sized and shaped to mate with the non-tissue piercing electrodes 722. In other examples, each non-tissue piercing electrode 722 can be an uninsulated, exposed portion of a monolithic member mounted within or on the insulating distal member 772. The intermediate portion of the monolithic member that is not used as an electrode can be insulated by the insulating distal member 772, or, if exposed to the surrounding environment, can be coated with an electrically insulating coating, such as parylene, polyurethane, silicone, epoxy, or other insulating coating.

[0094] When tissue piercing electrode assembly 712 is advanced into cardiac tissue, at least one non-tissue piercing electrode 722 may be placed against, in close contact with, or operably adjacent to a cardiac tissue surface to deliver pulses and / or sense cardiac electrical signals generated by the patient's heart. For example, when tissue piercing electrode assembly 712 is advanced into atrial tissue and through the central fibrous body until distal tip electrode 742 is in direct contact with ventricular tissue (e.g., ventricular myocardium and / or a portion of the ventricular conduction system), non-tissue piercing electrode 722 may be in contact with right atrial endothelial tissue to perform pacing and sensing in the atrium.

[0095] The non-tissue piercing electrode 722 may be coupled to the therapy delivery circuit 84 and the sensing circuit 86 enclosed by the housing 730 (see Figure 8), thereby acting together as a cathode electrode in combination with the proximal housing-based electrode 724 as a return anode to deliver atrial pacing pulses and sense atrial electrical signals (e.g., P waves). The switch circuit system included in the sensing circuit 86 can be activated under the control of the control circuit 80 to couple one or more non-tissue puncturing electrodes to the atrial sensing channel 87. The distal non-tissue puncturing electrodes 722 can be electrically isolated from each other, so that the switch circuit system included in the therapy delivery circuit 84 can individually select each individual electrode of the electrodes 722 to use a single electrode or a combination of two or more electrodes 722 as an atrial cathode electrode. The switch circuit system included in the therapy delivery circuit 84 can be activated under the control of the control circuit 80 to couple one or more non-tissue puncturing electrodes 722 to the atrial pacing circuit 83. Two or more non-tissue puncturing electrodes 722 can be selected as multiple atrial cathode electrodes at one time.

[0096] Certain non-tissue piercing electrodes 722 may be selected for atrial pacing and / or atrial sensing based on atrial capture threshold testing, electrode impedance, P-wave signal strength in the ECG signal, or other factors. For example, any combination of a single or two or more individual non-tissue piercing electrodes 722 may be selected to achieve reliable atrial pacing with minimal current consumption from the power supply 98, wherein the non-tissue piercing electrodes serve as cathode electrodes that provide an optimal combination of low pacing capture threshold amplitude and relatively high electrode impedance.

[0097] In some cases, when the tissue piercing electrode assembly 712 anchors the housing 730 at the implantation site, the distal-facing surface 738 can uniformly contact the atrial endocardial surface. In that case, all electrodes 722 can be selected together to form an atrial cathode. Alternatively, every other electrode 722 can be selected to form a multiple atrial cathode with a higher electrical impedance that is still evenly distributed along the distal-facing surface 738. Alternatively, a subset of one or more electrodes 722 along one side of the insulating distal member 772 can be selected to provide pacing at a desired site that reaches the lowest pacing capture threshold due to the relative position of the electrodes 722 relative to the paced atrial tissue.

[0098] In other cases, the distal-facing surface 738 may be oriented at an angle relative to the adjacent endocardial surface, depending on the location and direction of entry of the tissue piercing electrode assembly 712 into the cardiac tissue. In this case, one or more non-tissue piercing electrodes 722 may be angled relative to the endocardial surface to more closely contact the adjacent endocardial tissue than other non-tissue piercing electrodes 722. By providing multiple non-tissue piercing electrodes along the periphery of the insulating distal member 772, the tissue piercing electrode assembly 712 and the housing distal region 732 may not need to be substantially parallel relative to the cardiac surface (e.g., the right atrial endocardial surface). Anatomical and positional differences may cause the distal-facing surface 738 to be angled or tilted relative to the endocardial surface, however, the multiple non-tissue piercing electrodes 722 distributed along the periphery of the insulating distal member 772 increase the likelihood of good contact between one or more electrodes 722 and the adjacent cardiac tissue, thereby facilitating acceptable pacing thresholds and reliable cardiac event sensing using at least a subset of the multiple electrodes 722. Circumferential contact or fixation along the entire periphery of the insulating distal member 772 may not be required.

[0099] Each non-tissue piercing electrode 722 shown includes a first portion 722a extending along a distal-facing surface 738 and a second portion 722b extending along a circumferential surface 739. The first portion 722a and the second portion 722b can be continuous exposed surfaces, so that the active electrode surface is wrapped around the peripheral edge 776 of the insulating distal member 772, wherein the peripheral edge connects the distal-facing surface 738 and the circumferential surface 739. The non-tissue piercing electrode 722 may include one or more electrodes 722 along the distal-facing surface 738, one or more electrodes along the circumferential surface 739, one or more electrodes extending along the distal-facing surface 738 and the circumferential surface 739, or any combination thereof. The exposed surface of each non-tissue piercing electrode 722 can be flush with the corresponding distal-facing surface 738 and / or circumferential surface. In other examples, each non-tissue piercing electrode 722 may have a convex surface protruding from the insulating distal member 772. However, any raised surface of electrode 722 may define a smooth or rounded non-tissue piercing surface.

[0100] The distal fixation and electrode assembly 736 can seal the distal region of the housing 730 and can provide a basis for mounting the electrode 722. The electrode 722 can be referred to as a housing-based electrode. The electrode 722 can be carried by a shaft or other extension that extends the active electrode portion away from the housing 730, such as the distal tip electrode 742 located at the distal tip of the helical shaft 740 extending away from the housing 730. Other examples of non-tissue piercing electrodes coupled to the distal-facing surface and / or circumferential surface of the insulated distal member proposed herein include the distal housing-based ring electrode 22 ( Figure 7), in component 36( Figure 7 ) distal housing-based ring electrodes, button electrodes, other housing-based electrodes, and other circumferential ring electrodes extending circumferentially around the insulated distal member. Any non-tissue piercing electrodes directly coupled to the distal insulating member and peripherally coupled to the central tissue piercing electrode 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 ring 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.

[0101] The non-tissue piercing electrodes 722 and other examples listed above are expected to provide more reliable and effective atrial pacing and sensing than tissue piercing electrodes provided along the distal fixation and electrode assembly 736. The atrial wall is relatively thin compared to the ventricular wall. The tissue piercing atrial cathode electrode may extend too deep into the atrial tissue, resulting in unintended persistent or intermittent capture of the ventricular tissue. Because the ventricular signal has a greater signal strength in the ECG signal received via the tissue piercing atrial cathode electrode that is physically closer to the ventricular tissue, the tissue piercing atrial cathode electrode may interfere with the sensing of the atrial signal. The tissue piercing electrode assembly 712 can be firmly anchored in the ventricular tissue to stabilize the implantation position of the device 710 and provide reasonable certainty that the tip electrode 742 is sensing and pacing in the ventricular tissue and the non-tissue piercing electrode 722 is reliably pacing and sensing in the atrium. When the device 710 is implanted in the target implant area 4, for example, as Figure 1 Within the ventricular septum shown, the tip electrode 742 can reach the left ventricular tissue to pace the left ventricle, while the non-tissue piercing electrode 722 paces and senses in the right atrium. The length of the tissue piercing electrode assembly 712 ranges from about 4 mm to about 8 mm from the distal-facing surface 738 to the left ventricular tissue. In some cases, the device 710 can achieve four-chamber pacing by delivering atrial pacing pulses from the atrial pacing circuit 83 via the non-tissue piercing electrode 722 in the target implant area 4 to achieve bi-atrial (right atrium and left atrium) capture, and by delivering ventricular pacing pulses from the ventricular pacing circuit 85 via the tip electrode 742 that enters the ventricular tissue from the target implant area 4 to achieve bi-ventricular (right ventricle and left ventricle) capture.

[0102] Fig.10 shows an example using Figure 5An illustrative method 600 of detecting atrial activity using an acoustic or motion detector 11 of the present invention may be used to represent physiological response information. Specifically, method 600 may include detecting atrial contraction based on analysis of a motion signal (e.g., provided by motion detector 11), which may be performed by an IMD implanted in the patient's heart. In some embodiments, the motion signal may be provided by an IMD implanted in a ventricle (e.g., right ventricle) of the patient's heart. Method 600 may include starting an atrial contraction detection delay period 630 after identifying a ventricular excitation event. Method 600 may include opening an atrial contraction detection window 632 when the atrial contraction delay period expires. Method 600 may include analyzing the motion signal within the atrial contraction detection window.

[0103] The method 600 may include filtering the motion signal within the atrial contraction detection window, rectifying the filtered signal, and generating a derivative signal of the filtered and rectified motion signal within the atrial contraction detection window 634. The method 600 may include determining whether the amplitude of the derivative signal within the atrial contraction detection window exceeds a threshold 636. In response to determining that the amplitude of the derivative signal within the atrial contraction detection window exceeds the threshold ("yes" of 636), the method 600 may continue to detect an atrial contraction 638. Otherwise ("no" of 636), the method 600 may return to filtering, rectifying, and generating the derivative signal 634. Various techniques utilizing motion detectors that provide motion signals may be referenced in U.S. Patent No. 9,399,140 (Cho et al.), entitled “Atrial contraction detection by a ventricular leadless pacing device for atrio-synchronous ventricular pacing,” issued on July 26, 2016, the entire contents of which are incorporated herein by reference.

[0104] Reference Fig.11, heart sounds (HS) can be detected and used to represent physiological response information. As described herein, the amplitude and / or relative time interval of one or more of the S1 to S4 heart sounds can be used to optimize the patient's hemodynamic response to CRT or other cardiac therapies, including cardiac pacing and / or neural stimulation for achieving hemodynamic benefits. The first heart sound S1 corresponds to the beginning of ventricular contraction. Ventricular contraction begins when the action potential is conducted through the atrioventricular node (AV node) and rapidly depolarizes the ventricular myocardium. This event is characterized by the QRS complex on the ECG. When the ventricles contract, the pressure in the ventricles begins to rise, and when the ventricular pressure exceeds the atrial pressure, the mitral and tricuspid valves between the ventricles and atria suddenly close. This valve closure may produce S1. S1 typically has a duration of about 150ms and a frequency of about 20 to 250Hz. The amplitude of S1 can replace the measurement of LV contractility. Therefore, an increase in the S1 amplitude is positively correlated with an increase in LV contractility. Other measures, such as the pre-ejection period measured from the onset of the QRS to S1, can also be used as surrogate indices of myocardial contractility.

[0105] When the M1 peak and T1 peak in the S1 signal are separated, ventricular asynchrony can be observed, resulting in the separate closure of the mitral and tricuspid valves. The merging of M1 (mitral valve closure sound) and T1 (tricuspid valve closure sound) can be used as an indicator of improved ventricular synchrony.

[0106] Normally, after the QRS complex of the ECG and the closure of the mitral valve, left ventricular pressure (LVP) rises sharply and continues to rise during ventricular contraction until the aortic and pulmonary valves open, ejecting blood into the aorta and pulmonary arteries. During the ejection phase, ventricular contraction usually continues to cause blood pressure to rise in the ventricles, aorta, and pulmonary arteries. As contraction decreases, blood pressure decreases until the aortic and pulmonary valves close.

[0107] The second heart sound S2 may be produced by closing the aortic and pulmonary valves near the end of ventricular systole and the beginning of ventricular diastole. Therefore, S2 can be related to the diastolic pressure in the aorta and pulmonary artery. S2 typically has a duration of about 120 ms and a frequency of about 25 to 350 Hz. The time interval between S1 and S2, i.e., the S1-S2 time interval, can represent the systolic interval (STI) corresponding to the ventricular isovolumetric contraction (pre-ejection) and ejection phase of the cardiac cycle. The S1-S2 time interval can replace the measurement of stroke volume. In addition, the ratio of the pre-ejection period (Q-S1) to the S1-S2 time can be used as an indicator of myocardial contractility.

[0108] The third heart sound, S3, is associated with early, passive diastolic filling of the ventricles, while the fourth heart sound, S4, is associated with late, active filling of the ventricles caused by atrial contraction. Typically, the third heart sound is difficult to hear using a stethoscope in an average patient, while the fourth heart sound is not usually heard in an average patient. During an examination using a stethoscope, the presence of the third and fourth heart sounds may indicate a pathological condition. Because of their association with the diastolic function of the heart, the S3 and S4 heart sounds can be used to optimize pacing parameters. Typically, these heart sounds will be minimized or disappear when optimal pacing parameters are determined. As is known to those of ordinary skill in the art, other aspects of the S1 to S4 heart sounds and their timing can be used for cardiac pacing parameter optimization.

[0109] Fig.11 800 is a flowchart of a method for optimizing pacing control parameters using heart sounds according to one embodiment. The disclosed method may include one or more of the blocks shown in flowchart 800. Other examples of using heart sounds to optimize cardiac therapy are generally described in U.S. Patent No. 9,643,0134, entitled "System and method for pacing parameter optimization using heart sounds," issued on May 9, 2017, which is hereby incorporated by reference in its entirety.

[0110] The pacing parameter optimization method can be initiated at block 802. The optimization process can be initiated in response to a user command received via an external programmer. The user can initiate the HS-based optimization process using an external programmer or a networked computer at the time of initial IMD implantation or during an in-office follow-up visit, or during remote patient monitoring. Additionally or alternatively, the process shown in flowchart 800 can be an automated process that is initiated periodically or in response to sensing a need for therapy delivery or therapy adjustment based on sensed physiological signals, including sensed HS signals.

[0111] At box 804, a pacing control parameter to be optimized is selected. The control parameter can be a timing-related parameter, such as an AV interval or a VV interval. The pacing vector is another control parameter that can be selected for optimization at box 804. For example, when using a multipolar lead such as a coronary sinus lead, multiple bipolar or unipolar pacing vectors can be selected to pace in a given cardiac chamber. The pacing site associated with a particular pacing vector may have a significant effect on the hemodynamic benefit of pacing therapy. As such, the pacing vector is one pacing control parameter that can be optimized using the methods described herein.

[0112] A pacing sequence is initiated at box 806 using the initial parameter settings for the test parameters selected at box 804. In one embodiment, when optimizing the AV interval, ventricular pacing is delivered at the initial AV interval setting. It should be understood that the initial AV interval setting can be selected at box 806 by first measuring the intrinsic AV interval in a patient with complete AV conduction (i.e., no AV block). The initial AV interval can be a default pacing interval, a last programmed AV interval, or a minimum or maximum AV interval to be tested. Alternatively, if a VV interval is selected for optimization, the intrinsic interventricular conduction time can be measured first, and the paced VV interval can be iteratively adjusted starting with a VV interval that is longer, shorter, or approximately equal to the intrinsic VV conduction time.

[0113] An iterative process of adjusting the selected test parameter to at least two different settings is performed. The parameters can be adjusted to the different settings in any desired order (e.g., increasing, decreasing, random, etc.). For example, during adjustment of the AV interval, the initial AV interval can be set to just longer than or approximately equal to the measured intrinsic AV conduction time and then iteratively reduced to a minimum AV interval test setting. During pacing using each pacing parameter setting, an HS signal is acquired at box 808. At box 812, the iterative process advances to the next test parameter setting until all test parameter settings have been applied as determined at box 810 and an HS signal has been recorded for each setting.

[0114] HS signals may be acquired for multiple cardiac cycles, thereby enabling an overall average or averaging of HS parameter measurements acquired from each cardiac cycle. It should be understood that amplification, filtering, rectification, noise removal techniques, or other signal processing steps may be used to improve the signal-to-noise ratio of the HS signal, and that these steps may be different for each heart sound acquired (which may include any or all types of heart sounds).

[0115] At box 814, for each test parameter setting, at least one HS parameter measurement is determined from the recorded HS signal. For example, an IMD processor included in the programmer or an external processor, or a combination of both, can perform the HS signal analysis described herein. In one embodiment, at box 814, S1 and S2 are recorded using the S1 and S2 signals and HS parameters are measured. For example, the amplitude of S1, the V-S2 interval (wherein the V event can be a V paced or sensed R wave), and the S1-S2 interval are measured. The presence of S3 and / or S4 can be additionally noted, or these signals can be measured to determine the relevant parameters. HS signal parameters are determined for at least two different test parameter settings, for example, at least two different AV intervals, two or more different VV intervals, or two or more different pacing vectors.

[0116] At box 818, a trend is determined for each HS parameter determined at box 810 as a function of the pacing parameter test settings. In one embodiment, a trend is determined for each of the V-S2 interval, the S1 amplitude, and the S1-S2 interval. Other embodiments may include determining the separation of the M1 and T1 sounds during the S1 signal. Based on the trends of the HS parameters relative to the changing pacing control parameters, at box 820, the processor may automatically identify the optimal pacing parameter settings. Additionally, alternatively, and / or optionally, at box 822, the HS trends are reported and displayed on an external device such as a programmer or on a remote networked computer.

[0117] If a multipolar electrode is placed along a cardiac chamber (e.g., along a quadripolar lead of the LV), the pacing parameter to be tested is, for example, a pacing site or a pacing vector, which can be selected based on maximizing a HS-based ventricular contractility surrogate. In one embodiment, the amplitude of S1 is used as a surrogate for ventricular contractility, and the pacing site or vector associated with the maximum S1 is identified at block 820 as the optimal pacing vector setting.

[0118] Determining the trend of each HS parameter at block 818 may include determining whether the V-S2 interval trend exhibits an abrupt change in slope, such as from a substantially flat trend to a decreasing trend. The AV interval associated with the abrupt change in the V-S2 interval trend may be identified as the optimal AV interval setting. The optimal AV interval may be further identified based on other HS trends, such as the maximum S1 amplitude and / or the maximum S1-S2 interval.

[0119] In some embodiments, the automatically identified optimal pacing parameter settings may also be automatically programmed in the IMD at block 824. In other embodiments, a clinician or user reviews the reported HS data and the recommended pacing parameter settings and may accept the recommended settings or select another setting based on the HS data.

[0120] The HS sensing module or circuit system can be operably coupled to the control circuit 80 ( Figure 8 ), and is configured to receive analog signals from a HS sensor for sensing one or more heart sounds. For example, the HS sensing module may include one or more "channels" that are configured to specifically sense specific heart sounds based on the frequency, duration, and timing of the heart sounds. For example, the control circuit 80 may utilize the ECG / EGM sensing circuit system to set the HS sensing window used by the HS sensing module for sensing heart sounds. The HS sensing module may include one or more sensing amplifiers, filters, and rectifiers for optimizing the signal-to-noise ratio of the heart sound signals. Separate and unique amplification and filtering properties may be provided to sense each of the S1 to S4 sounds, thereby improving signal quality as desired.

[0121] Bioimpedance or intracardiac impedance can be measured and used to represent physiological response information. For example, by injecting current and measuring the voltage between electrodes (e.g., selected electrodes) of an electrode vector configuration, any IMD described herein can measure an intracardiac impedance signal. For example, by injecting current (e.g., non-pacing threshold current) between a first electrode (e.g., LV electrode) and an electrode located in the RA and measuring the voltage between the first and second electrodes, the IMD can measure an impedance signal. It will be appreciated that other vector pair configurations can be used for stimulation and measurement. Impedance can be measured between any set of electrodes surrounding the target tissue or heart chamber. Therefore, current can be injected and voltage can be measured to calculate the impedance on the same two electrodes (bipolar configuration), or current can be injected and the voltage on two pairs of electrodes (e.g., one pair for current injection and one pair for voltage sensing) separated, so it is a quadruple configuration. For a quadruple electrode configuration, the current injection and voltage sensing electrodes can be in a straight line (or closely parallel) with each other, and the voltage sensing electrode can be within the current sensing field. In such an embodiment, the VfA lead can be used for LV heart treatment or sensing. The impedance vector can be configured to cover a specific anatomical region of the target, such as the atrium or ventricle.

[0122] The example methods and / or apparatus described herein can monitor one or more electrode vector configurations. In addition, multiple impedance vectors can be measured simultaneously and / or periodically relative to one another. In at least one embodiment, the example methods and / or apparatus can use impedance waveforms to obtain selection data (e.g., find applicable reference points, allow measurements to be extracted from such waveforms, etc.) to optimize CRT.

[0123] As used herein, the term "impedance signal" is not limited to a raw impedance signal. It should be implied that the raw impedance signal may be processed, normalized, and / or filtered (e.g., to remove artifacts, noise, static electricity, electromagnetic interference (EMI), and / or extraneous signals) to provide an impedance signal. In addition, the term "impedance signal" may include various mathematical derivatives thereof, including the real and imaginary parts of the impedance signal, a conductance signal based on the impedance (i.e., the reciprocal or opposite number of the impedance), and the like. In other words, the term "impedance signal" may be understood to include a conductance signal, i.e., a signal that is the reciprocal of the impedance signal.

[0124] In one or more embodiments of the methods and / or apparatus described herein, various patient physiological parameters (e.g., intracardiac impedance, heart sounds, cardiac cycle intervals such as RR intervals, etc.) may be monitored for use in obtaining selected data to optimize CRT (e.g., setting AV and / or VV delays, optimizing cardiac contraction dZ / dt, for example by using and / or measuring first order derivatives of impedance, selecting pacing sites, selecting pacing vectors, lead placement, or assessing pacing capture from electrical and mechanical perspectives, selecting effective electrode vector configurations for pacing, etc.), where assessing pacing capture from electrical and mechanical perspectives, for example, electrical capture may not imply mechanical capture, and by viewing mechanical information from heart sounds and impedance, heart sounds and impedance may help assess whether electrical stimulation has captured the heart. For example, an intracardiac impedance signal between two or more electrodes may be monitored for use in providing such optimization.

[0125] Fig.12 An example of a method 850 for obtaining selection data for one of the device parameter options (e.g., one of the selectable device parameters that can be used to optimize CRT, such as potential AV delay that can be an optimal parameter) is shown. Other examples of using heart sounds to optimize cardiac therapy can generally be found in U.S. Patent No. 9,707,399, entitled "Cardiac resynchronization therapy optimization based on intracardiac impedance and heart sounds", issued on July 18, 2017, the entire contents of which are incorporated herein by reference.

[0126] As shown, pacing therapy is delivered using one of a plurality of device options (block 852) (e.g., the plurality of device parameter options may be selected, determined, and / or calculated AV delays, such as percentages of intrinsic AV delay, such as 40% intrinsic AV delay, 50% intrinsic AV delay, 60% intrinsic AV delay, 70% intrinsic AV delay, 80% intrinsic AV delay, etc.). For the device parameter option for pacing (block 852), selected data is acquired at each of a plurality of electrode vector configurations (e.g., intracardiac impedance is monitored over a plurality of cardiac cycles and selected data is extracted using such impedance signals). As shown by decision block 854, if the selected data has not been acquired from all desired electrode vector configurations, a loop of acquiring the selected data (e.g., the loop shown in blocks 858, 860, 862, and 864) is repeated. If the selected data has been acquired from all desired electrode vector configurations, therapy is delivered using another different device parameter option (block 856), and the loop is repeated. Fig.12The method 850 is repeated (eg, for different device parameter options) until selection data has been acquired for all of the different device parameter options (eg, selection data is collected at each of a plurality of electrode vector configurations for each different device parameter option).

[0127] As shown in a repeating loop of acquiring selected data for each desired electrode vector configuration (e.g., blocks 858, 860, 862, and 864), one of a plurality of electrode vector configurations is selected for acquiring selected data (block 858). For the selected electrode vector configuration, time reference points associated with at least a portion of the systolic portion of at least one cardiac cycle and / or time reference points associated with at least a portion of the diastolic portion of at least one cardiac cycle are acquired (block 860) (e.g., such as using heart sounds, analyzing minimum and maximum values ​​of an impedance signal, application of an algorithm based on a physiological parameter (e.g., RR interval), etc.). For example, time reference points associated with the systolic and / or diastolic portion of the cardiac cycle may be acquired, time reference points associated with one or more defined segments within the systolic and / or diastolic portion of the cardiac cycle may be acquired, and / or time reference points within or associated with one or more points and / or portions of the systolic and / or diastolic portion of the cardiac cycle may be acquired. Still further, for example, time reference points may be obtained that are associated only with the systolic or diastolic portion of the cardiac cycle, time reference points may be obtained that are associated only with one or more defined segments within the systolic or diastolic portion of the cardiac cycle, and / or time reference points may be obtained within or associated with one or more points and / or portions of only the systolic or only the diastolic portion of the cardiac cycle. In other words, reference points may be obtained that are associated with both the systolic and diastolic portions of the cardiac cycle or with only one of these portions of the cardiac cycle. Furthermore, for example, these reference points may represent or indicate measurement windows and / or time periods (e.g., intervals, points, etc.) over or during which intracardiac impedance may be measured for analysis as described herein.

[0128] An intracardiac impedance signal is acquired at the selected electrode vector configuration within approximately the same time frame (e.g., approximately simultaneously with the acquired fiducial points) (block 862). Using the acquired fiducial points and the acquired intracardiac impedance signal, measurements from the impedance signal are extracted based on the temporal fiducial points (block 864) (e.g., an integral of the impedance signal in a measurement window defined between the fiducial points, a maximum slope of the impedance signal in a measurement window defined between the fiducial points, the time between the fiducial points, a maximum impedance at the fiducial points, etc.). One or more of these measurements may be comparable to expected values ​​for these measurements, thereby allowing a determination to be made as to whether the measurement may indicate that the device parameter option may be an effective device parameter for optimizing therapy (e.g., if the device parameter option may be an optimal parameter may be determined using a scoring algorithm based on whether a plurality of such measurements meet certain criteria or thresholds).

[0129] Each device parameter option (e.g., Fig.12 In one or more embodiments, the measurement data are obtained for multiple cardiac cycles. The cardiac cycle in which the measurement data are obtained can be any suitable cardiac cycle. In one or more embodiments, the cardiac cycle selected to obtain the measurement data is based on the respiratory cycle. In at least one embodiment, the measurement data is obtained within a cardiac cycle that occurs at the end of the respiratory cycle (e.g., near the end of exhalation).

[0130] Fig.13 Depicted is used with e.g. Figure 1-5 An illustrative method 200 for monitoring the effectiveness of left ventricular capture for use with the illustrative systems and devices of 7-9. In particular, the method 200 can be used with the illustrative VfA device shown and described herein to deliver cardiac resynchronization therapy to a patient's heart. For example, the VfA device can deliver DDD(R), VVI(R), or VVI cardiac therapy. Thus, left ventricular beats can be delivered using a tissue puncture electrode implanted from the Koch triangle of the right atrium through the right atrial endothelium and central fibrous body to deliver cardiac therapy and / or sense electrical activity to the left ventricle located in the base and / or septal region of the left ventricular myocardium of the patient's heart.

[0131] As shown, method 200 includes monitoring left ventricular capture effectiveness 210, determining whether effective or ineffective left ventricular capture has exited 220, and adjusting left ventricular pacing 230 if left ventricular pacing is determined to be ineffective or inefficient. As shown, method 200 can continue to loop or periodically execute to continuously monitor left ventricular capture effectiveness. For example, effectiveness 210 can be continuously monitored, while determining whether effective or ineffective left ventricular capture has exited 220 can be periodically or intermittently. In addition, for example, effectiveness 210 can be continuously monitored, and whether effective or ineffective left ventricular capture has exited 220 can be determined over the most recent selected time period (e.g., the most recent 10 cardiac cycles).

[0132] Fig.15 Shows Fig.13 A more detailed flow chart of one embodiment of a depicted method 200. As shown, monitoring left ventricular capture effectiveness 210 may include delivering a left ventricular beat 212. The timing of the left ventricular beat and whether a left ventricular beat is delivered (e.g., in the case of early left ventricular activation) may depend on the therapy being delivered, but, nonetheless, electrical activity following the beat may be monitored 214. It should be understood that in this example, while electrical activity is monitored and used to determine left ventricular capture, any other form of physiological data may be acquired to determine and / or assess effective left ventricular capture, such as motion sensing or impedance sensing.

[0133] In particular, a near-field signal can be used to monitor a selected time period, a selected time, a cycle, or a time window 254 after a left ventricular beat. For example, two or more electrodes of a VfA device can be used to monitor near-field signals. In particular, a tissue puncture electrode implanted from the Koch triangle of the right atrium through the right atrial endothelium and the central fibrous body can be one of the two electrodes. The other electrode can be a right atrial electrode located in the right atrium of the patient. In one embodiment, the right atrial electrode can be in contact with the right atrial septum or other atrial tissue, and in another embodiment, the right atrial electrode can be located in the right atrium without contacting the right atrial tissue (e.g., "free floating" in the right atrium). Nevertheless, the monitored electrical signal can be referred to as a near-field signal because, for example, no electrode located outside the heart or away from the heart is used to monitor the signal.

[0134] The selected time period, selected time, cycle or time window 254 after the left ventricular beat can be between about 40 milliseconds and about 150 milliseconds. In one embodiment, the selected time period is about 84 milliseconds.

[0135] One or more metrics or comparisons may be used to evaluate the electrogram of the near-field signal over a selected time period. For example, various morphological features and the timing of such morphological features may be analyzed. In particular, the near-field electrogram may be analyzed using one or more of the following to determine effective left ventricular capture: one or more amplitudes at baseline immediately before or at the time of pacing delivery, amplitude minima relative to the baseline amplitude, maximum amplitude relative to the baseline amplitude, time of occurrence of minima, first or last occurring minimum or maximum, minimum or maximum occurring within a selected duration or following other events, slope (first derivative), second derivative, absolute minimum or maximum, etc.

[0136] Fig.14 A portion of an illustrative monitoring near-field electrogram 250 following ventricular beats for determining left ventricular capture effectiveness is depicted. In this example, a plurality of morphological features and morphological feature times are identified that can be used to determine left ventricular capture effectiveness 216 for left ventricular pacing therapy.

[0137] The absolute baseline amplitude 251 can be used to determine left ventricular capture effectiveness 216 for left ventricular pacing therapy. The baseline amplitude 251 can be defined as the amplitude immediately before or at the time of delivery of pacing. The absolute baseline amplitude 251 can be compared to an absolute baseline threshold. The absolute baseline threshold can be between approximately 0 millivolts and approximately 1 millivolt. In one embodiment, the absolute baseline threshold is 0.63 millivolts. If the absolute baseline amplitude 251 is less than the absolute baseline threshold, it can be determined that effective left ventricular capture is occurring.

[0138] The minimum negative deviation 252 within the selected negative deviation time period can be used to determine left ventricular capture effectiveness 216 for left ventricular pacing therapy. In particular, the minimum negative deviation 252 can be compared to a minimum threshold. The minimum threshold can be between about 1 millivolt and about 10 millivolts. In one embodiment, the minimum threshold is 1 millivolt. If the minimum negative deviation 252 is less than the minimum threshold (in other words, more negative than the minimum threshold), it can be determined that effective left ventricular capture is occurring.

[0139] In addition, as described above, the minimum negative deviation 252 is within or selected from a selected negative deviation time period. The selected negative deviation time period can be between about 40 milliseconds and about 100 milliseconds after the left ventricular beat. In one embodiment, the selected negative deviation time period is 84 milliseconds.

[0140] The time period between the left ventricular beat and the minimum negative deviation or the time period of the minimum negative deviation 253 can be used to determine the effectiveness of left ventricular capture 216 for left ventricular pacing therapy. In particular, the time period 253 between the left ventricular beat and the minimum negative deviation can be compared to an interval threshold. The interval threshold can be between about 40 milliseconds and about 60 milliseconds. In one embodiment, the interval threshold is 45 milliseconds. If the time period 253 between the left ventricular beat and the minimum negative deviation is less than the interval threshold, it can be determined that effective left ventricular capture is occurring.

[0141] The relative order of occurrence of the maximum amplitude and the minimum amplitude within the selected time period 254 can be used to determine the effectiveness of left ventricular capture 216 for left ventricular pacing therapy. For example, if the minimum amplitude occurs before the maximum amplitude, or the time of the minimum amplitude is before the time of the maximum amplitude, it can be determined that effective left ventricular capture is occurring. In other words, if the minimum negative deviation of the monitored electrical activity occurs before the maximum positive deviation of the monitored electrical activity, it can be determined that effective left ventricular capture is occurring. In one embodiment, the negative or minimum deviation timestamp corresponding to the minimum negative deviation or amplitude can be compared to the positive or maximum deviation timestamp corresponding to the maximum positive deviation or amplitude.

[0142] Thus, four illustrative criteria or metrics are described herein for determining the effectiveness of left ventricular capture of a left ventricular beat. Each of the four illustrative criteria or metrics can be used alone or in combination with one another. For example, if all four illustrative criteria have been met, then it can be determined that the left ventricular beat has been effectively captured. In other embodiments, meeting less than all four criteria, such as two of the four criteria or three of the four criteria, can indicate effective capture.

[0143] Thus, the effectiveness of capture of the left ventricular beats can be determined 216, and the method or process 210 can continuously loop (as indicated by the arrow extending from process 216 to process 212), thereby monitoring and evaluating the capture of each left ventricular beat. In practice, depending on the specific cardiac therapy being delivered, the amount of effective left ventricular beats can be calculated over a plurality of paced and / or intrinsic (e.g., non-paced) heartbeats. The count of an elapsed time period (e.g., a day or more, a week or more, device life, time period since last device interrogation, etc.) can be presented on a device programmer interface as a diagnostic of effective left ventricular pacing.

[0144] If it is determined that left ventricular pacing is not effectively captured, the example method 200 can further adjust left ventricular pacing 230. Such determination to adjust can occur over multiple beats or cardiac cycles, for example, to eliminate anomalies, etc.

[0145] Furthermore, different therapies may make different kinds of adjustments to left ventricular pacing therapy to improve effective capture over time. Fig.15 As shown, in DDD(r) cardiac therapy, n valid LV beats in m cardiac cycles may be used to determine whether effective LV capture is occurring 222. In other words, it may be determined whether a first number of LV beats within a second number of cardiac cycles have not achieved effective LV tissue capture.

[0146] Thus, an assessment of the effectiveness of left ventricular pacing over multiple cardiac cycles can be used to determine whether to adjust pacing in DDD(r) cardiac therapy. The metric can be described as "rolling" so that the previous m cardiac cycles can be continuously evaluated. In addition, process 222 can be described based on a selected percentage of valid left ventricular beats over the past m cardiac cycles. For example, if it is determined that at least 90 left ventricular beats were effective over the past 100 left ventricular paced cardiac cycles, it can be determined that the DDD(r) cardiac therapy has effective left ventricular capture and no adjustment is needed. Conversely, if it is determined that less than 90 left ventricular beats were effective over the past 100 left ventricular paced cardiac cycles, it can be determined that the DDD(r) cardiac therapy does not have adequate left ventricular capture and adjustments 232 should be made.

[0147] For example, the left ventricular pacing amplitude can be increased 232 by a selected value or a selected percentage. The selected value can be between about 0.25 millivolts and about 1 millivolt. In one embodiment, the selected value is 0.5 millivolts. Additionally, the left ventricular pacing amplitude can be increased until a threshold, limit, or boundary is reached. In other words, an upper threshold can be used such that the amplitude can be increased until it reaches the upper threshold. The upper threshold can be between 4 mV and 10 mV. In one embodiment, the upper threshold is about 6 mV.

[0148] In other embodiments, instead of or in combination with increasing the pacing amplitude, one or more other pacing settings, such as pulse width, pulse frequency, etc., may be increased or adjusted.

[0149] In addition, the AV delay can be adjusted 232. As used herein, the term "AV delay" or "AV pacing interval" refers to a determined delay between atrial activation (As or Ap) and the delivery time of ventricular pacing (Vp), wherein atrial activation can include intrinsic atrial activation (As), or atrial sense, or paced atrial activation (Ap). Specifically, the AV delay (which can include multiple different AV delays corresponding to multiple different heart rates) can be reduced by a selected amount or a selected percentage. For example, the AV delay can be reduced by 10 milliseconds until a valid left ventricle is captured or a lower limit is reached, for example, 60 milliseconds for As and 70 milliseconds for Ap. In addition, for example, the AV delay can be reduced by 5% until a valid left ventricle is captured or a lower limit is reached.

[0150] In some embodiments, the amplitude, AV delay, and other pacing settings 232 may be adjusted until left ventricular capture is obtained, which may be determined using the same or similar process as monitoring left ventricular capture effectiveness 210. After left ventricular pacing has been adjusted to achieve effective capture, the method may return to monitoring left ventricular capture effectiveness 210. Additionally, it should be understood that monitoring left ventricular capture effectiveness 210 may be occurring continuously even while the other processes of the method are being performed. In other words, monitoring left ventricular capture effectiveness 210 may be a permanent process that is always running.

[0151] In addition, if Fig.15 As shown, in VVI(r) cardiac therapy, n valid left ventricular beats and x valid intrinsic left ventricular activations within m cardiac cycles may be used to determine whether effective left ventricular capture is occurring 224. In other words, it may be determined whether a first number of left ventricular beats within a second number of cardiac cycles have not achieved effective left ventricular tissue capture, and it may be determined whether a third number of intrinsic left ventricular activations have been sensed within the second number of cardiac cycles.

[0152] Thus, assessment of the effectiveness of left ventricular pulsation and intrinsic activity over multiple cardiac cycles can be used to determine whether to adjust pacing in VVI(r) cardiac therapy. Similar to the metric used in DDD(r) therapy, this metric can be described as "rolling."

[0153] For example, if it is determined that at least 90 left ventricular beats are valid over the past 100 cardiac cycles (including paced and intrinsic cardiac cycles), it can be determined that the VVI(r) cardiac therapy has effective left ventricular capture and does not need adjustment. Conversely, if it is determined that less than 90 left ventricular beats and at least 10 intrinsic left ventricular activations are valid over the past 100 cardiac cycles, it can be determined that the VVI(r) cardiac therapy does not have adequate left ventricular capture and should be adjusted 234. In addition, the process 224 can be described based on a selected percentage of valid left ventricular beats within the past m cardiac cycles and a selected percentage of valid intrinsic activation within the past m cardiac cycles.

[0154] Adjustment of the VVI(r) cardiac therapy may include adjusting the heart rate using, for example, a heart rate delay 232. For example, the heart rate delay or LV-LV time may be decreased to increase the heart rate (e.g., 10 beats per minute) until effective left ventricular capture is achieved or a limit is reached, e.g., 130 beats per minute. In other embodiments, the heart rate delay may be decreased by a selected percentage until effective left ventricular capture is achieved or a limit is reached. After left ventricular pacing has been adjusted to achieve effective capture, the method may return to monitoring left ventricular capture effectiveness 210.

[0155] Further, in VVI cardiac therapy, n valid left ventricular beats within m cardiac cycles and whether any intrinsic left ventricular activation is sensed within the m cardiac cycles can be used to determine whether effective left ventricular capture is occurring 226. In other words, it can be determined 226 whether the first number of left ventricular beats has not achieved effective left ventricular capture and to determine that no intrinsic left ventricular activation is sensed.

[0156] Thus, assessment of the effectiveness of left ventricular pulsation and intrinsic activity over multiple cardiac cycles can be used to determine whether to adjust pacing in VVI cardiac therapy. Similar to the metric used in DDD(r) therapy, this metric can be described as "rolling".

[0157] For example, if it is determined that at least 90 left ventricular beats in the past 100 cardiac cycles are effective, it can be determined that the VVI cardiac therapy has effective left ventricular capture and does not need adjustment. Conversely, if it is determined that less than 90 left ventricular beats in the past 100 cardiac cycles are effective and intrinsic left ventricular excitation is not detected, it can be determined that the VVI cardiac therapy does not have adequate left ventricular capture and should be adjusted 236. Adjustment 236 of the VVI cardiac therapy may include adjusting the pacing output, including pacing amplitude and / or another pacing setting, which may be similar to the adjustment process 232 described herein for DDD(r) pacing. After left ventricular pacing has been adjusted to achieve effective capture, the method can return to monitoring left ventricular capture effectiveness 210.

[0158] In addition, if Fig.13 and 15 If one or more of the processes shown determine invalid left ventricular tissue capture, an alarm may be issued. For example, the implantable medical device may issue an alarm to an external device such as a smartphone, other medical device, or reader. In addition, for example, a sound may be emitted from one or more devices to alert the user.

[0159] Illustrative Embodiments

[0160] Embodiment 1: An implantable medical device comprising:

[0161] Multiple electrodes, including:

[0162] a tissue-piercing electrode that can be implanted from the Koch triangle of the right atrium through the right atrial endothelium and central fibrous body to deliver cardiac therapy or sense electrical activity to the left ventricle at the base and / or septum of the left ventricle of the patient's heart, and

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

[0164] a therapy delivery circuit operably coupled to the plurality of electrodes to deliver cardiac therapy to a heart of a patient;

[0165] sensing circuitry operably coupled to the plurality of electrodes to sense electrical activity of the patient's heart; and

[0166] a controller including processing circuitry operably coupled to the therapy delivery circuitry and the sensing circuitry, the controller configured to monitor left ventricular capture effectiveness by:

[0167] operating the therapy delivery circuit to deliver a left ventricular beat using the tissue piercing electrode;

[0168] monitoring the electrical activity of the left ventricle by following the left ventricular pulsation using the tissue piercing electrode via the sensing circuit; and

[0169] The effectiveness of left ventricular tissue capture of the left ventricular beat is determined based on the monitored electrical activity.

[0170] Embodiment 2: A method comprising:

[0171] Providing a tissue-penetrating electrode that is implanted from the Koch triangle of the right atrium through the right atrial endothelium and the central fibrous body to deliver cardiac therapy or sense electrical activity to the left ventricle at the base and / or septum of the left ventricle of the patient's heart;

[0172] providing a right atrial electrode positionable within the right atrium to deliver cardiac therapy to or sense electrical activity of the right atrium of the patient's heart;

[0173] delivering a left ventricular beat using the tissue-piercing electrode;

[0174] Following the left ventricular beat, monitoring the electrical activity of the left ventricle using the tissue piercing electrode; and

[0175] The effectiveness of left ventricular tissue capture of the left ventricular beat is determined based on the monitored electrical activity.

[0176] Embodiment 3: An embodiment as described in any one of embodiments 1 to 2, wherein following the left ventricular beating, monitoring the electrical activity of the left ventricle using the tissue puncture electrode comprises: monitoring the electrical activity of the left ventricle using the tissue puncture electrode and the right atrial electrode.

[0177] Embodiment 4: The embodiment as described in any one of embodiments 1 to 3, wherein determining the effectiveness of left ventricular tissue capture of left ventricular beats based on the monitored electrical activity includes: comparing the absolute baseline amplitude of the monitored electrical activity with an absolute baseline amplitude threshold.

[0178] Embodiment 5: The embodiment as described in any one of embodiments 1 to 4, wherein determining the effectiveness of left ventricular tissue capture of the left ventricular beat based on the monitored electrical activity includes: comparing a minimum negative deviation within a selected time period after the left ventricular beat to a minimum threshold.

[0179] Embodiment 6: Embodiment as described in any one of embodiments 1 to 5, wherein determining the effectiveness of left ventricular tissue capture of the left ventricular beat based on the monitored electrical activity includes: comparing the time period between the left ventricular beat and the minimum negative deviation with an interval threshold.

[0180] Example 7: An example as described in any one of embodiments 1 to 6, wherein determining the effectiveness of left ventricular tissue capture of left ventricular beats based on the monitored electrical activity includes: determining whether a minimum negative deviation of the monitored electrical activity occurs before a maximum positive deviation of the monitored electrical activity.

[0181] Embodiment 8: The embodiment as described in any one of embodiments 1 to 7, wherein the controller is further configured to execute, or the method further comprises:

[0182] Monitor left ventricular capture effectiveness over multiple cardiac cycles;

[0183] determining that effective left ventricular capture is not occurring based on the monitored left ventricular capture effectiveness during the plurality of cardiac cycles; and

[0184] In response to determining that effective left ventricular capture is not occurring, left ventricular pacing is adjusted.

[0185] Example 9: An embodiment as described in Example 8, wherein determining that effective left ventricular capture is not occurring based on the effectiveness of left ventricular capture monitored during the multiple cardiac cycles includes: determining whether a first number of left ventricular beats within a second number of cardiac cycles have not achieved effective left ventricular tissue capture.

[0186] Example 10: An embodiment as described in any of Examples 8 to 9, wherein adjusting left ventricular pacing includes: adjusting one or both of the left ventricular pacing amplitude of the left ventricular beat and the delay between atrial sensing or beating and the left ventricular beat until effective left ventricular tissue capture of the left ventricular beat is determined.

[0187] Embodiment 11: The embodiment of embodiment 8, wherein determining that effective left ventricular capture is not occurring based on the left ventricular capture effectiveness monitored during the plurality of cardiac cycles comprises:

[0188] determining that effective left ventricular tissue capture has not been achieved for a first number of left ventricular beats in a second number of cardiac cycles; and

[0189] It is determined that a third number of intrinsic left ventricular activations have been sensed during the second number of cardiac cycles.

[0190] Embodiment 12: The embodiment of embodiment 11, wherein, in response to determining that the first number of left ventricular beats did not achieve effective left ventricular capture and a third number of intrinsic left ventricular activation has been sensed, adjusting left ventricular pacing comprises:

[0191] The heart rate delay between the left ventricular sensing or beat and the subsequent left ventricular beat is adjusted until effective left ventricular tissue capture of the left ventricular beat is determined.

[0192] Embodiment 13: The embodiment of embodiment 11, wherein, in response to determining that the first number of left ventricular beats have not achieved effective left ventricular capture and intrinsic left ventricular activation has not been sensed, adjusting left ventricular pacing comprises:

[0193] A left ventricular pacing amplitude of the left ventricular beat is adjusted until effective left ventricular tissue capture of the left ventricular beat is determined.

[0194] Embodiment 14: The embodiment of any one of embodiments 1 to 13, wherein the controller is further configured to execute, the method further comprising issuing an alarm if invalid left ventricular tissue capture is determined.

[0195] Embodiment 15: The embodiment of any one of embodiments 1 to 14, wherein monitoring left ventricular capture effectiveness comprises periodically monitoring left ventricular capture effectiveness over a selected number of cardiac cycles.

[0196] Embodiment 16: An implantable medical device comprising:

[0197] Multiple electrodes, including:

[0198] a tissue-piercing electrode that can be implanted from the Koch triangle of the right atrium through the right atrial endothelium and central fibrous body to deliver cardiac therapy or sense electrical activity to the left ventricle at the base and / or septum of the left ventricle of the patient's heart, and

[0199] a right atrial electrode positionable within the right atrium to deliver cardiac therapy to or sense electrical activity of the right atrium of the patient's heart;

[0200] a therapy delivery circuit operably coupled to the plurality of electrodes to deliver cardiac therapy to a heart of a patient;

[0201] sensing circuitry operably coupled to the plurality of electrodes to sense electrical activity of the patient's heart; and

[0202] a controller comprising processing circuitry operably coupled to the therapy delivery circuitry and the sensing circuitry, the controller being configured to:

[0203] Left ventricular beat therapy using tissue-piercing electrodes;

[0204] monitoring left ventricular capture effectiveness over a plurality of cardiac cycles based on electrical activation monitored using at least the tissue-piercing electrode;

[0205] determining that effective left ventricular capture is not occurring based on the monitored left ventricular capture effectiveness during the plurality of cardiac cycles; and

[0206] In response to determining that effective left ventricular capture is not occurring, left ventricular pacing is adjusted.

[0207] The various aspects disclosed herein may be combined in combinations different from those specifically presented in the specification and drawings. It should also be understood that, depending on the example, certain actions or events of any of the processes or methods described herein may be performed in different sequences, may be added, merged, or omitted entirely (e.g., all described actions or events may not be necessary for performing these techniques). In addition, although certain aspects of the present disclosure are described as being performed by a single module or unit for clarity, the techniques of the present disclosure may be performed by a combination of units or modules associated with, for example, a medical device.

[0208] In one or more examples, the described techniques may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, the functions may be stored as one or more instructions or codes on a computer-readable medium and executed by a hardware-based processing unit. A computer-readable medium may include a non-transitory computer-readable medium, which corresponds to a tangible medium, such as a data storage medium (e.g., RAM, ROM, EEPROM, flash memory, or any other medium that can be used to store desired program code in the form of instructions or data structures and can be accessed by a computer).

[0209] The instructions may be executed by one or more processors, such as one or more digital signal processors (DSPs), general purpose microprocessors, application specific integrated circuits (ASICs), field programmable logic arrays (FPGAs), or other equivalent integrated or discrete logic circuit systems. Thus, the term "processor" as used herein may refer to any of the foregoing structures or any other physical structure suitable for implementing the described techniques. Moreover, the techniques may be fully implemented in one or more circuits or logic elements.

[0210] All references and publications cited herein are expressly incorporated by reference in their entirety for all purposes, unless any aspect of the incorporation is directly inconsistent with this disclosure.

[0211] Unless otherwise specified, all scientific and technical terms used herein have the meanings commonly used in the art. The definitions provided herein are to facilitate understanding of certain terms frequently used herein and are not meant to limit the scope of the present disclosure.

[0212] Unless otherwise indicated, all numbers expressing feature sizes, amounts, and physical properties used in the specification and claims may be understood as being modified by the terms "exactly" or "approximately." Therefore, unless indicated to the contrary, the numerical parameters set forth in the foregoing specification and the appended claims are approximations that may vary depending on the desired properties sought to be obtained by one skilled in the art utilizing the teachings disclosed herein or, for example, within the typical range of experimental error.

[0213] References to numerical ranges by endpoints include all numbers within that range (e.g., 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, and 5) and any range within that range. As used herein, the term "up to" or "not greater than" a number (e.g., up to 50) includes that number (e.g., 50), and the term "not less than" a number (e.g., not less than 5) includes that number (e.g., 5).

[0214] The terms "coupled" or "connected" refer to elements being directly connected to each other (in direct contact with each other) or indirectly connected (having one or more elements between and connected to the two elements). Both terms can be modified by "operably" and "operably", which can be used interchangeably to describe a coupling or connection configured to allow components to interact to perform at least some functions (e.g., a first medical device can be operably coupled to another medical device to send information in the form of data or receive data from it).

[0215] Directional terms, such as "top", "bottom", "side" and "end", are used to describe the relative positions of components and are not meant to limit the orientation of the embodiments 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.

[0216] Reference to "one embodiment," "an embodiment," "certain embodiments," or "some embodiments," etc., means 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 appearances of these phrases in various places do not necessarily refer to the same embodiment of the present disclosure. Furthermore, in one or more embodiments, the particular features, configurations, compositions, or characteristics may be combined in any suitable manner.

[0217] 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 to include "and / or," unless the content clearly dictates otherwise.

[0218] As used herein, "having", "including", "comprising", etc. are used in their open-ended sense and generally mean "including but not limited to". It will be understood that "consisting essentially of", "consisting of", etc. are included in "comprising", etc.

[0219] The term "and / or" means one or all of the listed elements or a combination of at least two of the listed elements.

[0220] The phrases "at least one," "comprising at least one," and "one or more" followed by a list refer to any one of the items in the list and any combination of two or more items in the list.

Claims

1. An implantable medical device comprising: Multiple electrodes, including: A tissue-piercing electrode capable of being implanted in the myocardial base and / or septum of the left ventricle of the patient's heart from the Koch triangle of the right atrium through the right atrial endothelium and the central fibrous body to deliver cardiac therapy to the left ventricle or sense its electrical activity in the myocardial base and / or septum of the left ventricle of the patient's heart, and a right atrial electrode positionable within the right atrium to deliver cardiac therapy to or sense electrical activity of the right atrium 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; a sensing circuit operatively coupled to the plurality of electrodes to sense electrical activity of the patient's heart; as well as a controller including processing circuitry operably coupled to the therapy delivery circuitry and the sensing circuitry, the controller configured to monitor left ventricular capture effectiveness by: operating the therapy delivery circuit to deliver a left ventricular beat using the tissue piercing electrode; monitoring electrical activity of the left ventricle by following the left ventricular pulsation using the tissue piercing electrode via the sensing circuit; as well as A left ventricular tissue capture effectiveness of the left ventricular beat is determined based on the monitored electrical activity.

2. The device according to claim 1, wherein: Following the beating of the left ventricle, monitoring the electrical activity of the left ventricle using the tissue puncture electrode includes: monitoring the electrical activity of the left ventricle using the tissue puncture electrode and the right atrial electrode.

3. The device according to any one of claims 1 to 2, wherein: Determining left ventricular tissue capture effectiveness of the left ventricular beat based on the monitored electrical activity includes comparing an absolute baseline amplitude of the monitored electrical activity to an absolute baseline amplitude threshold.

4. The device according to any one of claims 1 to 3, wherein: Determining left ventricular tissue capture effectiveness of the left ventricular beat based on the monitored electrical activity includes comparing a minimum negative deviation within a selected time period following the left ventricular beat to a minimum threshold.

5. The device according to any one of claims 1 to 4, wherein: Determining left ventricular tissue capture effectiveness of the left ventricular beat based on the monitored electrical activity includes comparing a time period between the left ventricular beat and a minimum negative deviation to an interval threshold.

6. The device according to any one of claims 1 to 5, wherein: Determining effectiveness of left ventricular tissue capture of the left ventricular beat based on the monitored electrical activity includes determining whether a minimum negative deviation of the monitored electrical activity occurs before a maximum positive deviation of the monitored electrical activity.

7. The apparatus according to any one of claims 1 to 6, wherein the controller is further configured to perform: Monitor left ventricular capture effectiveness over multiple cardiac cycles; determining that effective left ventricular capture is not occurring based on the monitored left ventricular capture effectiveness during the plurality of cardiac cycles; as well as In response to determining that effective left ventricular capture is not occurring, left ventricular pacing is adjusted.

8. The device according to claim 7, wherein: Determining that effective left ventricular capture is not occurring based on the monitored left ventricular capture effectiveness during the plurality of cardiac cycles includes determining whether a first number of left ventricular beats within a second number of cardiac cycles have not achieved effective left ventricular tissue capture.

9. A device according to any one of claims 7 to 8, wherein adjusting left ventricular pacing includes: adjusting one or both of the left ventricular pacing amplitude of the left ventricular beat and the delay between atrial sensing or beating and the left ventricular beat until effective left ventricular tissue capture of the left ventricular beat is determined.

10. The device according to claim 7, wherein: Determining that effective left ventricular capture is not occurring based on the monitored left ventricular capture effectiveness during the plurality of cardiac cycles comprises: determining that effective left ventricular tissue capture has not been achieved for a first number of left ventricular beats within a second number of cardiac cycles; and It is determined that a third number of intrinsic left ventricular activations have been sensed within the second number of cardiac cycles.

11. The device according to claim 10, wherein: In response to determining that the first number of left ventricular beats did not achieve effective left ventricular capture and a third number of intrinsic left ventricular activation has been sensed, adjusting left ventricular pacing comprises: The heart rate delay between the left ventricular sensing or beat and the subsequent left ventricular beat is adjusted until effective left ventricular tissue capture of the left ventricular beat is determined.

12. The device according to claim 10, wherein: In response to determining that the first number of left ventricular beats have not achieved effective left ventricular capture and intrinsic left ventricular activation has not been sensed, adjusting left ventricular pacing comprises: A left ventricular pacing amplitude of the left ventricular beat is adjusted until effective left ventricular tissue capture of the left ventricular beat is determined.

13. The apparatus according to any one of claims 1 to 12, wherein the controller is further configured to perform: if ineffective left ventricular tissue capture is determined, issuing an alarm.

14. The apparatus according to any one of claims 1 to 13, wherein monitoring left ventricular capture effectiveness comprises: periodically monitoring left ventricular capture effectiveness over a selected number of cardiac cycles.

15. A method comprising: Providing a tissue-piercing electrode, which is implanted in the myocardial base and / or septum of the left ventricle of the patient's heart from the Koch triangle of the right atrium through the right atrial endothelium and the central fibrous body to deliver cardiac therapy to the left ventricle or sense its electrical activity in the myocardial base and / or septum of the left ventricle of the patient's heart; providing a right atrial electrode positionable within the right atrium to deliver cardiac therapy to or sense electrical activity of the right atrium of the patient's heart; delivering a left ventricular beat using the tissue-piercing electrode; Following the left ventricular beat, monitoring the electrical activity of the left ventricle using the tissue piercing electrode; and A left ventricular tissue capture effectiveness of the left ventricular beat is determined based on the monitored electrical activity.

16. The method according to claim 15, wherein: Following the beating of the left ventricle, monitoring the electrical activity of the left ventricle using the tissue puncture electrode includes: monitoring the electrical activity of the left ventricle using the tissue puncture electrode and the right atrial electrode.

17. The method according to any one of claims 15 to 16, wherein: Determining left ventricular tissue capture effectiveness of the left ventricular beat based on the monitored electrical activity includes comparing an absolute baseline amplitude of the monitored electrical activity to an absolute baseline amplitude threshold.

18. The method according to any one of claims 15 to 17, wherein: Determining left ventricular tissue capture effectiveness of the left ventricular beat based on the monitored electrical activity includes comparing a minimum negative deviation within a selected time period following the left ventricular beat to a minimum threshold.

19. The method according to any one of claims 15 to 18, wherein: Determining left ventricular tissue capture effectiveness of the left ventricular beat based on the monitored electrical activity includes comparing a time period between the left ventricular beat and a minimum negative deviation to an interval threshold.

20. The method according to any one of claims 15 to 19, wherein: Determining effectiveness of left ventricular tissue capture of the left ventricular beat based on the monitored electrical activity includes determining whether a minimum negative deviation of the monitored electrical activity occurs before a maximum positive deviation of the monitored electrical activity.

21. The method according to any one of claims 15 to 20, wherein the method further comprises: Monitor left ventricular capture effectiveness over multiple cardiac cycles; determining that effective left ventricular capture is not occurring based on the monitored left ventricular capture effectiveness during the plurality of cardiac cycles; as well as In response to determining that effective left ventricular capture is not occurring, left ventricular pacing is adjusted.

22. The method according to claim 21, wherein: Determining that effective left ventricular capture is not occurring based on the monitored left ventricular capture effectiveness during the plurality of cardiac cycles includes determining whether a first number of left ventricular beats within a second number of cardiac cycles have not achieved effective left ventricular tissue capture.

23. A method according to any one of claims 21 to 22, wherein adjusting left ventricular pacing includes: adjusting one or both of the left ventricular pacing amplitude of the left ventricular beat and the delay between atrial sensing or beating and the left ventricular beat until effective left ventricular tissue capture of the left ventricular beat is determined.

24. The method according to claim 21, wherein: Determining that effective left ventricular capture is not occurring based on the monitored left ventricular capture effectiveness during the plurality of cardiac cycles comprises: determining that effective left ventricular tissue capture has not been achieved for a first number of left ventricular beats within a second number of cardiac cycles; and It is determined that a third number of intrinsic left ventricular activations have been sensed within the second number of cardiac cycles.

25. The method according to claim 24, wherein: In response to determining that the first number of left ventricular beats did not achieve effective left ventricular capture and a third number of intrinsic left ventricular activation has been sensed, adjusting left ventricular pacing comprises: The heart rate delay between the left ventricular sensing or beat and the subsequent left ventricular beat is adjusted until effective left ventricular tissue capture of the left ventricular beat is determined.

26. The method according to claim 24, wherein: In response to determining that the first number of left ventricular beats have not achieved effective left ventricular capture and intrinsic left ventricular activation has not been sensed, adjusting left ventricular pacing comprises: A left ventricular pacing amplitude of the left ventricular beat is adjusted until effective left ventricular tissue capture of the left ventricular beat is determined.

27. The method of any one of claims 15 to 26, wherein the method further comprises issuing an alarm if ineffective left ventricular tissue capture is determined.

28. The method of any one of claims 15 to 27, wherein monitoring left ventricular capture effectiveness comprises periodically monitoring left ventricular capture effectiveness over a selected number of cardiac cycles.

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