Systems and methods for selection of pacing therapy

Abstract

An implantable medical device system is disclosed herein that may be configured to sense one or more sensor signals comprising at least one cardiac signal and deliver cardiac pacing according to a pacing configuration selected from among at least a first pacing configuration and a second pacing configuration. The first pacing configuration may be delivered by delivering first ventricular pacing pulses only to one or more left ventricular myocardial pacing sites. The second pacing configuration may be delivered by delivering second ventricular pacing pulses to at least a conduction system pacing site.

Description

Attorney Docket: A0013968W001SYSTEMS AND METHODS FOR SELECTION OF PACING THERAPYREFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of the filing date of provisional U.S. Application Serial No. 63 / 754,273, filed February 5, 2025, the entire content incorporated herein by reference.TECHNICAL FIELD

[0002] The disclosure relates generally to medical device systems and, more particularly, medical device systems configured for cardiac pacing.BACKGROUND

[0003] Some types of implantable medical devices (IMDs), such as cardiac pacemakers or implantable cardioverter defibrillators, may be used to provide cardiac therapy to a patient via one or more electrodes. The cardiac therapy may be delivered to the heart in the form of pulses or shocks for pacing, cardioversion or defibrillation, or cardiac resynchronization therapy (CRT). CRT may help enhance cardiac output by resynchronizing the electromechanical activity of the ventricles of the heart in patients with conditions such as ventricular dyssynchrony. Some IMDs may sense intrinsic depolarizations of the heart and control the delivery of CRT to the heart based on the sensed intrinsic depolarizations.

[0004] Conduction system pacing (CSP) is a technology that uses the heart’s native conduction system to provide paced depolarizations and resulting contractions that better mimic intrinsic depolarizations and contractions, which may improve the health and pumping efficiency of the heart. Example t pes of conduction system pacing include His bundle pacing, left bundle branch pacing (LBBP), right bundle branch pacing (RBBP), and bilateral bundle branch pacing (BBBP). Example locations from which the conduction system may be accessed include the ventricular septum via the right ventricle, and the atrio-ventricular septum via the right atrium, e.g., at the area of the triangle of Koch. In some examples, CSP may provide cardiac resynchronization without requiring delivery of cardiac pacing to the left side of the heart.SUMMARY

[0005] The techniques of this disclosure generally relate to an IMD or IMD system configured to deliver ventricular pacing pulses according to a pacing configuration that is selected automatically by processing circuitry of the IMD or IMD system. The pacing configuration may be selected based on an assessment performed to evaluate one or more of device-related conditions, patient-related conditions and / or cardiac-related conditions, which may be cardiacAttorney Docket: A0013968W001electrical activity conditions and / or cardiac mechanical activity conditions. The selectable ventricular pacing configurations may include a left ventricular myocardial only (LV-only) pacing configuration in which ventricular pacing pulses are delivered only to one or more LV myocardial pacing sites, e.g., along the left ventricular lateral free wall via a coronary sinus lead. The selectable ventricular pacing configurations may include a conduction sy stem pacing (CSP) only pacing configuration in which ventricular pacing pulses are delivered to one or more conduction system pacing sites (which may or may not include myocardial capture in combination with conduction system capture due to non-selective CSP capture or selective CSP capture, respectively) without delivering LV myocardial pacing at a different myocardial pacing site, e.g., an LV pacing site along the LV lateral free wall where LV-only pacing is delivered. The selectable ventricular pacing configurations may include a combination of CSP plus LV myocardial pacing in which ventricular pacing pulses are delivered to one or more conduction system pacing sites (which may or may not include myocardial capture in combination with conduction system capture) and delivering LV my ocardial pacing at one or more LV myocardial pacing sites, e.g., along the LV lateral free wall via a coronary sinus lead. This combination of CSP plus LV myocardial pacing can be referred to as ‘LOT-CRT” pacing, which may generally refer to left ventricular optimized cardiac resynchronization therapy and may involve CSP delivered in the area of the LBB in combination with LV myocardial pacing along the lateral free wall.

[0006] In one example, the disclosure provides a medical device system including sensing circuitry configured to sense one or more sensor signals including at least one cardiac signal and therapy del i x erx circuitry configured to deliver cardiac pacing according to a pacing configuration that is selected by control circuitry' of the medical device. The pacing configuration may be selected from among at least a first pacing configuration and a second pacing configuration. The therapy delivery circuitry is configured to deliver first ventricular pacing pulses according to the first pacing configuration by delivering the first ventricular pacing pulses only to one or more left ventricular myocardial pacing sites and deliver second ventricular pacing pulses according to the second pacing configuration by delivering the second ventricular pacing pulses to at least a first conduction system pacing site. The control circuitry- is further configured to perform a pacing configuration assessment by analyzing the at least one cardiac signal and select the pacing configuration from among at least the first pacing configuration and the second pacing configuration based on the pacing configuration assessment.

[0007] In another example, the disclosure provides a method including sensing one or more sensor signals including at least one cardiac signal and delivering cardiac pacing according to a pacing configuration that is selected from among at least a first pacing configuration and aAttorney Docket: A0013968W001second pacing configuration. Delivering the cardiac pacing can include delivering first ventricular pacing pulses according to the first pacing configuration by delivering the first ventricular pacing pulses only to one or more left ventricular myocardial pacing sites and delivering second ventricular pacing pulses according to the second pacing configuration by delivering the second ventricular pacing pulses to at least a first conduction system pacing site. The method may further include performing a pacing configuration assessment by analyzing the at least one cardiac signal and selecting the pacing configuration from among at least the first pacing configuration and the second pacing configuration based on the pacing configuration assessment.

[0008] In another example, the disclosure provides non-transitory computer readable media storing a set of instructions that, when executed by processing circuitry of a medical device system, cause the medical device system to sense one or more sensor signals including at least one cardiac signal and deliver cardiac pacing according to a pacing configuration that is selected from among at least a first pacing configuration and a second pacing configuration. The instructions may further cause the medical device system to deliver first ventricular pacing pulses when the first pacing configuration is selected by delivering the first ventricular pacing pulses only to one or more left ventricular myocardial pacing sites and deliver second ventricular pacing pulses when the second pacing configuration is selected by delivering the second ventricular pacing pulses to at least a first conduction system pacing site. The instructions may further cause the medical device system to perform a pacing configuration assessment by analyzing the at least one cardiac signal and select the pacing configuration from among at least the first pacing configuration and the second pacing configuration based on the pacing configuration assessment.

[0009] The details of one or more aspects of the disclosure are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the techniques described in this disclosure will be apparent from the description and drawings, and from the claims.BRIEF DESCRIPTION OF DRAWINGS

[0010] FIG. 1 is a diagram of an example medical device system that may be configured to deliver pacing therapy according to pacing configuration selection methods disclosed herein.

[0011] FIG. 2 is a diagram of the IMD of FIG. 1 and the leads of the medical device system of FIG. 1 in more detail.

[0012] FIG. 3 is a diagram of an illustrative configuration of the IMD of FIG. 1.

[0013] FIG. 4 is a block diagram of an illustrative programmer.Attorney Docket: A0013968W001

[0014] FIGS. 5A-5B show the patient’s heart implanted with an implantable medical electrical lead coupled to an IMD to deliver bundle branch pacing according to some examples of an IMD system that may perform the methods disclosed herein.

[0015] FIG. 6 is a diagram of an IMD system 10’ having a lead implanted in an interventricular septal location for delivering CSP.

[0016] FIG. 7 is a diagram of an IMD system that may be configured to deliver cardiac pacing therapy according to the techniques disclosed herein in yet another example.

[0017] FIG. 8 is a flow chart of an illustrative method of a device selecting a pacing configuration based on patient status and device longevity.

[0018] FIG. 9 is a flow chart of a method for controlling the ventricular pacing configuration for delivering a cardiac pacing therapy by an IMD or IMD system according to another example.

[0019] FIG. 10 is a flow chart of a method for controlling the pacing configuration by an IMD or IMD system according to another example.

[0020] FIG. 11 is a flow chart of methods for performing a pacing configuration assessment by an IMD or IMD system according to some examples.DETAILED DESCRIPTION

[0021] The techniques of this disclosure generally relate to selection of a cardiac pacing configuration by a device (e.g., implantable medical devices (IMDs)) configured to deliver a variety of cardiac pacing therapies, including but not limited to. left ventricular (LV) only pacing, CSP-only (e.g., left bundle branch area pacing (LBBAP)), and CSP in combination with LV myocardial pacing (e.g., Left Bundle Branch-Optimized Cardiac Resynchronization Therapy or more generally left ventricular optimized cardiac resynchronization therapy (“LOT-CRT”)) that may be delivered using implantable medical devices (IMDs). Illustrative systems, devices, methods, and processes that are used to select and deliver an appropriate cardiac pacing therapy are described herein with respect to FIGS. 1-11.

[0022] It is be understood that the illustrative methods and processes described herein may be executed, or performed, using cardiac resynchronization therapy pacemaker (CRT-P) devices, cardiac resynchronization therapy pacemaker defibrillator (CRT-D) devices, dual chamber implantable pulse generator (IPG) devices, and dual chamber implantable cardioverterdefibrillator (ICD) devices. Additionally, such devices may be configured to apply to LBBAP, LOT-CRT, biventricular (BiV), or LV-only pacing.

[0023] FIG. 1 is a conceptual diagram of an exemplary therapy system 10 that may be configured to deliver pacing therapy, such as cardiac fusion pacing therapy, to a patient 14. While the patient 14 is show n as a human, the patient 14 may also be a variety of other types of animals. TheAttorney Docket: A0013968W001therapy system 10 may include an implantable medical device 16 (IMD), which may be coupled to leads 18, 20. 22. and a programmer 24. The IMD 16 may be. e.g., an implantable pacemaker, cardioverter, and / or defibrillator, that delivers, or provides, electrical signals (e.g., paces, etc.) to the heart 12 of the patient 14 via electrodes coupled to the IMD 16 (e.g., coupled to one or more of the leads 18, 20, 22), senses electrical signals from the heart 12 of the patient 14 via electrodes coupled to the IMD (e.g., coupled to one or more of the leads 18, 20, 22), and / or senses mechanical activity' (e.g., sounds, motions, vibrations, etc.) of the heart 12 of the patient 14 via a mechanical heart activity sensor.

[0024] The leads 18, 20, 22 extend into the heart 12 of the patient 14 to sense electrical activity7of the heart 12 and / or to deliver electrical stimulation to the heart 12. In the example shown in FIG. 1. the right ventricular (RV) lead 18 extends through one or more veins (not show n), the superior vena cava (not shown), and the right atrium 26, and into the right ventricle 28. The left ventricular (LV) coronary' sinus lead 20 extends through one or more veins, the vena cava, the right atrium 26, and into the coronary sinus 30 to a region adjacent to the free wall of the left ventricle 32 of the heart 12. The right atrial (RA) lead 22 extends through one or more veins and the vena cava, and into the right atrium 26 of the heart 12.

[0025] The IMD 16 may sense, among other things, electrical signals attendant to the depolarization and repolarization of the heart 12 via electrodes coupled to at least one of the leads 18, 20, 22 and mechanical heart activity signals of the heart 12 using a mechanical heart activity sensor. In some examples, the IMD 16 provides pacing therapy (e.g., pacing pulses) to the heart 12 based on the electrical signals sensed within the heart 12. The IMD 16 may be operable to adapt or adjust one or more parameters associated with the pacing therapy such as, e.g., pacing rate, R-R interval, paced AV (PAV) therapy delay or interval, sensed AV (SAV) therapy delay or interval, VV pacing interval or delay, and other various timings, pulse width, amplitude, voltage, burst length, etc. Further, the IMD 16 may be operable to use various electrode configurations to deliver pacing therapy, which may be unipolar, bipolar, quadripolar, or further multipolar. Hence, a multipolar lead system may provide, or offer, multiple electrical vectors to pace from. A pacing vector may include at least one cathode, which may be at least one electrode located on at least one lead, and at least one anode, which may be at least one electrode located on at least one lead (e.g., the same lead, or a different lead) and / or on the casing, or can, of the IMD, or electrode apparatus. While improvement in cardiac function as a result of the pacing therapy may primarily depend on the cathode, the electrical parameters like impedance, pacing threshold voltage, current drain, longevity, etc. may be more dependent on the pacing vector, which includes both the cathode and the anode. The IMD 16 may also provide defibrillation therapy and / or cardioversion therapy via electrodes located on at least one of the leads 18, 20, 22. Further, theAttorney Docket: A0013968W001IMD 16 may detect arrhythmia of the heart 12, such as fibrillation of the ventricles 28, 32, and deliver defibrillation therapy to the heart 12 in the form of electrical pulses (e.g., one or more high-voltage cardioversion / defibrillation shocks). In some examples, IMD 16 may be programmed to deliver a progression of therapies, e.g., pulses (CV / DF shocks) with increasing energy levels, until a fibrillation of the heart 12 is stopped.

[0026] In some examples, the programmer 24 may be a mobile computing device (such as a smartphone) or a computer workstation. The programmer 24 may include a user interface that receives input from a user. The user interface may include, for example, a keypad and a display, which may, for example, be a liquid cry stal display (LCD) or light emitting diode (LED) display. The keypad may take the form of an alphanumeric keypad or a reduced set of keys associated with particular functions. The programmer 24 can additionally or alternatively include a peripheral pointing device, such as a mouse, via which a user may interact with the user interface. In some embodiments, a display of the programmer 24 may include a touch screen display, and a user may interact with the programmer 24 via the display.

[0027] A user, such as a physician, technician, patient, or other user, may interact with the programmer 24 to communicate with the IMD 16. For example, a user may interact with the programmer 24 to retrieve physiological or diagnostic information from the IMD 16. Further, for example, a user may also interact with the programmer 24 to program the IMD 16, e.g., select values for operational parameters of the IMD.

[0028] Further, for example, a user may use the programmer 24 to retrieve information from the IMD 16 regarding other sensed physiological or diagnostic parameters of the patient 14 such as, for example, right ventricular dysfunction, left ventricular dysfunction, intracardiac or intravascular pressure, activity, posture, respiration, or thoracic impedance. As another example, the user may use the programmer 24 to retrieve information from the IMD 16 regarding the performance or integrity of the IMD 16 or other components of the system 10, such as the leads 18, 20, and 22, or a power source of the IMD 16.

[0029] A user may use the programmer 24 to review information from the IMD 16. In some examples, a user may activate features of the IMD 16 by entering a single command via the programmer 24, such as depression of a single key or combination of keys of a keypad or a single point-and-select action with a pointing device.

[0030] The IMD 16 and the programmer 24 may communicate via wireless communication using any techniques known in the art. Examples of communication techniques may include, for example, low frequency or radiofrequency (RF) telemetry, but other techniques are also contemplated. In some examples, the programmer 24 may include a programming head that mayAttorney Docket: A0013968W001be placed proximate to the patient's body near the IMD 16 implant site in order to improve the quality or security of communication between the IMD 16 and the programmer 24.

[0031] FIG. 2 is a conceptual diagram of the IMD 16 and the leads 18, 20, 22 of therapy system 10 of FIG. 1 in more detail. The leads 18, 20, 22 may be electrically coupled to a therapy delivery module (e.g., for delivery of CRT), a sensing module (e.g., for sensing one or more signals from one or more electrodes), and / or any other modules of the IMD 16 via a connector block 34. In some examples, the proximal ends of the leads 18, 20, 22 may include electrical contacts that electrically couple to respective electrical contacts within the connector block 34 of the IMD 16. In addition, in some examples, the leads 18, 20, 22 may be mechanically coupled to the connector block 34 with the aid of set screws, connection pins, or another suitable mechanical coupling mechanism.

[0032] Each of the leads 18, 20, 22 includes an elongated insulative lead body, which may carry a number of conductors (e.g., concentric coiled conductors or straight conductors) separated from one another by insulation (e.g., tubular insulative sheaths). In the illustrated example, bipolar electrodes 40, 42 are located proximate to a distal end of the lead 18. In addition, electrodes 44, 45, 46, 47 are located proximate to a distal end of the lead 20 and bipolar electrodes 48, 50 are located proximate to a distal end of the lead 22.

[0033] The electrodes 40, 44, 45, 46, 47, 48 may take the form of, or define, ring electrodes, and the electrodes 42, 50 may take the form of, or define, extendable helix tip electrodes mounted retractably within the insulative electrode heads 52, 54, 56, respectively. Each of the electrodes 40, 42, 44, 45, 46, 47, 48, 50 may be electrically coupled to a respective one of the conductors (e.g., coiled and / or straight) within the lead body of its associated lead 18, 20, 22, and thereby coupled to a respective one of the electrical contacts on the proximal end of the leads 18, 20, 22.

[0034] The electrodes 40, 42, 44, 45, 46, 47, 48, 50 may further be used to sense electrical signals (e.g., morphological waveforms within electrograms (EGM)) attendant to the depolarization and repolarization of the heart 12. The electrical signals are conducted to the IMD 16 via the respective leads 18, 20, 22. In some examples, the IMD 16 may also deliver pacing pulses via the electrodes 40, 42, 44, 45, 46, 47, 48, and 50 to cause depolarization of cardiac tissue of the patient's heart 12. In some examples, as illustrated in FIG. 2, the IMD 16 includes one or more housing electrodes, such as housing electrode 58, which may be formed integrally with an outer surface of a housing 60 (e.g., hermetically sealed housing) of the IMD 16 or otherwise coupled to the housing 60. Any of the electrodes 40, 42, 44, 45, 46, 47, 48, 50 may be used for unipolar sensing or pacing in combination with the housing electrode 58. It is generally understood by those skilled in the art that other electrodes can also be selected to define, or be used for, pacing and sensing vectors. Further, any of the electrodes 40, 42, 44, 45, 46, 47, 48, 50,Attorney Docket: A0013968W00158, when not being used to deliver pacing therapy, may be used to sense electrical activity during pacing therapy.

[0035] As described in further detail with reference to FIG. 2, the housing 60 may enclose a therapy delivery module that may include a stimulation generator (sometimes referred to as a “pulse generator"’ or “signal generator”) for generating cardiac pacing pulses and defibrillation or cardioversion shocks, as well as a sensing module for monitoring the electrical signals of the patient’s heart (e.g., the patient's heart rhythm). The leads 18, 20, 22 may also include elongated electrodes 62, 64, 66, respectively, which may take the form of a coil. The IMD 16 may deliver defibrillation shocks to the heart 12 via any combination of the elongated electrodes 62, 64, 66 and the housing electrode 58. The electrodes 58, 62, 64. 66 may also be used to deliver cardioversion pulses to the heart 12. Further, the electrodes 62, 64, 66 may be fabricated from any suitable electrically conductive material, such as, but not limited to, platinum, platinum alloy, and / or other materials know n to be usable in implantable defibrillation electrodes. Since electrodes 62, 64, 66 are not generally configured to deliver pacing therapy, any of the electrodes 62, 64, 66 may be used to sense electrical activity and may be used in combination with any of the electrodes 40, 42, 44, 45, 46, 47, 48, 50, 58. In at least one embodiment, the RV elongated electrode 62 may be used to sense electrical activity of a patient's heart during the delivery of pacing therapy (e.g., in combination with the housing electrode 58, or defibrillation electrode-to-housing electrode vector).

[0036] The above-described configuration of the therapy system 10 is merely one example. In other examples, the therapy system may include epicardial leads and / or patch electrodes instead of, or in addition to, the transvenous leads 18, 20, 22 illustrated in FIG. 1. In further embodiments, the therapy system 10 may be implanted in / around the cardiac space without transvenous leads (e.g., leadless / wireless pacing systems) or with leads implanted (e.g., implanted transvenously or using approaches) into the left chambers of the heart (in addition to or replacing the transvenous leads placed into the right chambers of the heart as illustrated in FIG. 1). Further, in one or more embodiments, the IMD 16 may not be implanted within the patient 14. For example, the IMD 16 may deliver various cardiac therapies to the heart 12 via percutaneous leads that extend through the skin of the patient 14 to a variety of positions within or outside of the heart 12. In one or more embodiments, the system 10 may utilize wireless pacing (e.g., using energy transmission to the intracardiac pacing component(s) via ultrasound, inductive coupling, RF, etc.) and sensing cardiac activation using electrodes on the can / housing and / or on subcutaneous leads.

[0037] Other example therapy systems that provide electrical stimulation therapy to the heart 12 may include any suitable number of leads coupled to the IMD 16, and each of the leads mayAttorney Docket: A0013968W001extend to any location within or proximate to the heart 12. Such other therapy systems may include three transvenous leads located as illustrated in FIGS. 1-2. Still further, therapy systems may include a single lead that extends from the IMD 16 into the right atrium 26 or two leads that extend into a respective one of the right atrium 26 and the left atrium. In one example, the IMD 16, as a cardiac resynchronization therapy (CRT) device with a left ventricular (LV) lead, may be useful for a HFpEF (heart failure with preserved ejection fraction) patient if there is a complete AV node block as a LV lead can be more beneficial than a RV lead in such patients.

[0038] FIG. 3 is a functional block diagram of an illustrative configuration of the IMD 16. As shown, the IMD 16 may include a control module 81, a therapy delivery module 84 (e.g., which may include a stimulation generator), a sensing module 86, and a power source 90. The control module, or apparatus, 81 may include a computing apparatus (also referred to herein as “processor”) 80, memory 82, and a telemetry module, or apparatus, 88. The memory 82 may include computer-readable instructions that, when executed, e.g., by the computing apparatus 80, cause the IMD 16 and / or the control module 81 to perform various functions attributed to the IMD 16 and / or the control module 81 described herein. Further, the memory 82 may include any volatile, non-volatile, magnetic, optical, and / or electrical media, such as a random-access memory (RAM), read-only memory (ROM), non-volatile RAM (NVRAM), electrically erasable programmable ROM (EEPROM), flash memory', and / or any other digital media.

[0039] The computing apparatus 80 of the control module 81 may include any one or more of a microprocessor, a controller, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field-programmable gate array (FPGA), and / or equivalent discrete or integrated logic circuitry. In some examples, the computing apparatus 80 may include multiple components, such as any combination of one or more microprocessors, one or more controllers, one or more DSPs, one or more ASICs, and / or one or more FPGAs, as well as other discrete or integrated logic circuitry. The functions attributed to the computing apparatus 80 herein may be embodied as software, firmw are, hardware, or any combination thereof. Depiction, description or claiming of different features as specific modules or circuitry is intended to highlight different functional aspects and does not necessarily imply that such functions must be realized by separate hardware, firmware or software components or by any particular circuit architecture. Rather, functionality associated with one or more circuits depicted, described or claimed herein may be performed by separate hardware, firmw are or software components, or integrated within common hardware, firmware or software components. For example, processes for performing an assessment and selecting a pacing configuration as described herein may be implemented in computing apparatus (“processor”) 80 executing instructions stored in memory 82 and relying on input from sensing module 86 and test pulses delivered by therapy delivery' module 84 under the control of controlAttorney Docket: A0013968W001pacer timing and control module 87. Nonetheless, a “pacing configuration selection circuit” as used herein may encompass all of these listed components; this example illustrates an interpretive principle applicable to any module, circuit, circuitry, etc. Providing software, hardware, and / or firmware to accomplish the described functionality in the context of any modem pacemaker, given the disclosure herein, is within the abilities of one of skill in the art.

[0040] The control module 81 may control the therapy delivery module, or apparatus, 84 to deliver therapy (e.g., LV-only pacing, LOT-CRT pacing, LBBAP pacing, etc.) to the heart 12 according to a selected one or more therapy programs, which may be stored in the memory 82, and based on algorithms, or methods, described further below. More specifically, the control module 81 (e.g., the computing apparatus 80) may control various parameters of the electrical stimulus delivered by the therapy delivery module 84 such as, e.g., sensed and rate responsive paced AV delay profiles, sensed and paced intrinsic AV delays or intervals, AV pacing delays or intervals, VV pacing delays or internals, pacing pulses with the amplitudes, pulse widths, frequency, or electrode polarities, etc., which may be specified by one or more selected therapy programs (e.g.. adaptive rate responsive AV delay profile programs, adaptive pacing therapy program, target CRT settings, adjustment, and / or modifications programs, pacing therapy programs, pacing recover}’ programs, capture management programs, etc.). As show n, the therapy delivery’ module 84 is electrically coupled to electrodes 40, 42, 44, 45, 46, 47, 48, 50, 58, 62, 64, 66, e.g., via conductors of the respective lead 18, 20, 22, or, in the case of housing electrode 58, via an electrical conductor disposed within housing 60 of IMD 16. Therapy delivery module 84 may be configured to generate and deliver electrical stimulation therapy such as pacing therapy to the heart 12 using one or more of the electrodes 40, 42, 44, 45, 46, 47, 48, 50, 58, 62, 64, 66.

[0041] For example, the therapy delivery module 84 may deliver pacing stimulus (e.g., pacing pulses) via ring electrodes 40, 44, 45, 46, 47, 48 coupled to leads 18, 20, 22 and / or helical tip electrodes 42, 50 of leads 18, 22. Further, for example, therapy delivery' module 84 may deliver defibrillation shocks to the heart 12 via at least two of electrodes 58, 62, 64, 66. In some examples, therapy delivery module 84 may be configured to deliver pacing, cardioversion, or defibrillation stimulation in the form of electrical pulses. In other examples, therapy delivery module 84 may be configured to deliver one or more of these types of stimulation in the form of other signals, such as sine waves, square w aves, and / or other substantially continuous time signals.

[0042] The IMD 16 may further include a switch module, or apparatus, 85 and the control module 81 (e.g., the computing apparatus 80) may use the swatch module 85 to select, e.g., via a data / address bus, w hich of the available electrodes are used to deliver therapy such as pacingAttorney Docket: A0013968W001pulses for pacing therapy, or which of the available electrodes are used for sensing. The switch module 85 may include a switch array, switch matrix, multiplexer, or any other type of switching device suitable to selectively couple the sensing module, or apparatus, 86 and / or the therapy delivery module 84 to one or more selected electrodes. More specifically, the therapy delivery module 84 may include a plurality of pacing output circuits. Each pacing output circuit of the plurality of pacing output circuits may be selectively coupled, e.g., using the switch module 85, to one or more of the electrodes 40, 42, 44, 45, 46, 47, 48, 50, 58, 62, 64, 66 (e.g., a pair of electrodes for delivery of therapy to a bipolar or multipolar pacing vector). In other words, each electrode can be selectively coupled to one of the pacing output circuits of the therapy delivery module using the switch module 85.

[0043] The sensing module 86 is coupled (e.g., electrically coupled) to sensing apparatus, which may include, among additional sensing apparatus, the electrodes 40, 42, 44, 45, 46, 47, 48, 50, 58, 62, 64, 66 to monitor electrical activity of the heart 12, e.g., electrocardiogram (ECG) / electrogram (EGM) signals, etc. The ECG / EGM signals may be used to measure or monitor activation times (e.g., ventricular activations times, etc.), heart rate (HR), heart rate variability (HRV), heart rate turbulence (HRT), deceleration / acceleration capacity, deceleration sequence incidence, T-wave altemans (TWA), P-wave to P-wave delays or intervals (also referred to as P-P delays or intervals or A-A delays or intervals), R-wave to R-wave delays or intervals (also referred to as the R-R delays or R-R intervals or heart rate), P-wave to QRS complex delays or intervals (also referred to as P-wave to R-wave delays or intervals, P-R delays or intervals, A-V delays or intervals, or P-Q delays or intervals). QRS-complex morphology, QRS complex intervals, or QRS duration, ST segment (i.e., the segment that connects the QRS complex and the T-wave), T-wave changes, QT intervals, electrical vectors, etc.

[0044] The sensing module 86 may further include a mechanical heart activity sensor 92 configured to monitor mechanical activity of the patient’s heart 12. The mechanical activity of the patient’s heart may include or be representative of one or more motion, movement, sounds, and vibrations of the patient's heart 12 and one or more portions or anatomical mechanisms of the patient’s heart 12. For example, the mechanical heart activity sensor 92 may be configured to monitor mechanical activity corresponding to or indicative of closure of the atrioventricular valves (i.e., the mitral valve and the tricuspid valve), closure of the semilunar valves (i.e., the aortic valve and the pulmonary valve), chamber fillings, chamber contractions, and transitions from rapid to slow filling.

[0045] It is to be understood that, although the mechanical heart activity sensor 92 is depicted as being part of the sensing module 86 within the housing 60 of the IMD 16, the mechanical heart activity sensor 92 may be external to the housing 60 such as, e.g., part of or included within oneAttorney Docket: A0013968W001of the leads 18. 20, 22, and positioned in various locations within or about the patient’s heart 12. Further, in at least one embodiment, the IMD 16 may be a leadless IMD including the mechanical heart activity sensor 92 therein and may be positioned within a chamber of the patient’s heart 12 thereby placing the mechanical heart activity sensor 92 within the chamber of the patient's heart 12.

[0046] The switch module 85 may also be used with the sensing module 86 to select which of the available electrodes are used, or enabled, to, e.g., sense electrical activity of the patient's heart (e.g., one or more electrical vectors of the patient's heart using any combination of the electrodes 40, 42, 44, 45, 46, 47, 48, 50, 58, 62, 64, 66). Likewise, the switch module 85 may also be used with the sensing module 86 to select hich of the available electrodes are not to be used (e.g., disabled) to, e.g., sense electrical activity of the patient's heart (e.g., one or more electrical vectors of the patient's heart using any combination of the electrodes 40, 42, 44, 45, 46, 47, 48, 50, 58, 62, 64, 66), etc. In some examples, the control module 81 may select the electrodes that function as sensing electrodes via the switch module within the sensing module 86, e.g., by providing signals via a data / address bus.

[0047] In some examples, sensing module 86 includes a channel that includes an amplifier with a relatively wider pass band than the R-wave or P-wave amplifiers. Signals from the selected sensing electrodes may be provided to a multiplexer and thereafter converted to multi-bit digital signals by an analog-to-digital converter for storage in memory 82, e.g., as an electrogram (EGM). In some examples, the storage of such EGMs in memory 82 may be under the control of a direct memory access circuit.

[0048] In some examples, the control module 81 may operate as an interrupt-driven device and may be responsive to interrupts from pacer timing and control module 87, where the interrupts may correspond to the occurrences of sensed P-waves and R-waves and the generation of cardiac pacing pulses. Any mathematical calculations may be performed by the computing apparatus 80 and any updating of the values or intervals controlled by the pacer timing and control module 87 may be executed, or take place, following such interrupts. A portion of memory' 82 may be configured as a plurality of recirculating buffers, capable of holding one or more series of measured intervals, which may be analyzed by, e.g., the computing apparatus 80 in response to the occurrence of a pace or sense interrupt to determine whether the patient's heart 12 is presently exhibiting atrial or ventricular tachyarrhythmia.

[0049] The computing apparatus 80 of IMD 16 may be configured to evaluate, or assess, at least heart rate and intrinsic AV delays for use in adapting rate responsive AV delay profiles. For example, heart rate may be monitored, which may then be used to determine sensed and paced AV delays using sensed and rate responsive paced AV delay profiles, respectively. Further, forAttorney Docket: A0013968W001example, sensed and paced intrinsic AV delays may be intermittently monitored or sampled, which are then used to adapt, or adjust, the rate responsive sensed or paced AV delay profiles. Further, the computing apparatus 80 of IMD 16 may detect a tachyarrhythmia episode, such as a ventricular fibrillation, ventricular tachycardia, fast ventricular tachyarrhythmia episode, or a NST (normal sinus tachycardia) episode, based on electrocardiographic activity of heart 12 that is monitored via sensing module 86. For example, sensing module 86, with the aid of at least some of the electrodes 40, 42, 44, 46, 48, 50, 58, 62, 64, and 66 (shown in FIGS. 1-2), may generate an electrocardiogram (ECG) or electrogram (EGM) signal that indicates the electrocardiographic activity. Alternatively, sensing module 86 may be coupled to sense electrodes that are separate from the stimulation electrodes that deliver electrical stimulation to heart 12 (shown in FIGS. 1-2), and may be coupled to one or more different leads than leads 18, 20, 22 (shown in FIGS. 1-2). The ECG / EGM signal may be indicative of the depolarization of heart 12.

[0050] The telemetry' module 88 of the control module 81 may include any suitable hardware, firmware, software, or any combination thereof for communicating with another device, such as a programmer (such as, for example, a mobile computing devices or smartphones). For example, under the control of the computing apparatus 80, the telemetry module 88 may receive downlink telemetry7from and send uplink telemetry to a programmer or mobile computing device with the aid of an antenna, which may be internal and / or external. The computing apparatus 80 may provide the data to be uplinked to a programmer or a mobile computing device and the control signals for the telemetry circuit within the telemetry module 88, e.g., via an address / data bus. In some examples, the telemetry module 88 may provide received data to the computing apparatus 80 via a multiplexer.

[0051] The various components of the IMD 16 are further coupled to a power source 90. which may include a rechargeable or non-rechargeable battery. A non-rechargeable battery may be selected to last for several years, while a rechargeable battery may be inductively charged from an external device, e.g., on a daily or weekly basis.

[0052] FIG. 4 is a block diagram of an illustrative programmer 24. As show n in FIG. 4, the programmer 24 includes a processor 100, a memory 102, a user interface 104, a telemetry module 106, and a power source 108. The programmer 24 may be a dedicated hardware device with dedicated software for programming of IMD 16. Alternatively, the programmer 24 may be an off-the-shelf computing device (e.g., mobile computing device such as a smartphone) running an application that enables programmer 24 to program IMD 16.

[0053] The processor 100 can take the form one or more microprocessors, DSPs, ASICs, FPGAs, programmable logic circuitry, or the like, and the functions attributed to processor 100 herein may be embodied as hardw are, firmware, softw are or any combination thereof. The memory' 102Attorney Docket: A0013968W001may store instructions that cause processor 100 to provide the functionality ascribed to the programmer 24 herein, and information used by processor 100 to provide the functionality ascribed to the programmer 24 herein. The memory 102 may include any fixed or removable magnetic, optical, or electrical media, such as RAM, ROM, CD-ROM, hard or floppy magnetic disks, EEPROM, or the like. The memory 102 may also include a removable memory7portion that may be used to provide memory updates or increases in memory capacities. A removable memory may also allow IMD and / or patient data to be easily transferred to another computing device, or to be removed before the programmer 24 is used to program therapy for another patient. The memory7102 may also store information that controls therapy delivery7by the IMD 16.

[0054] The programmer 24 may communicate wirelessly with the IMD 16. such as using RF communication or proximal inductive interaction. This wireless communication is possible through the use of the telemetry module 106, which may be coupled to an internal antenna or an external antenna. An external antenna that is coupled to programmer 24 may correspond to the programming head that may be placed over the heart 12, as described above with reference to FIG. 1. The telemetry module 106 may be similar to telemetry module 88 of the IMD 16 of FIG.3.

[0055] The telemetry7module 106 may also be configured to communicate with another computing device via wireless communication techniques, or direct communication through a wired connection. Examples of local wireless communication techniques that may be employed to facilitate communication between the programmer 24 and another computing device include RF communication according to the 802.11 or Bluetooth specification sets, infrared communication, e.g.. according to the IrDA (Infrared Data Association) standard, or other standard or proprietary telemetry7protocols. In this manner, other external devices may be capable of communicating with the programmer 24 without needing to establish a secure wireless connection.

[0056] The power source 108 delivers operating power to the components of programmer 24 and may include a battery7and a power generation circuit to produce the operating power. In some embodiments, the battery may be rechargeable to allow extended operation. Recharging may be accomplished by7electrically7coupling power source 108 to a cradle or plug that is connected to an alternating current (AC) outlet. In addition or alternatively, recharging may be accomplished through proximal inductive interaction between an external charger and an inductive charging coil within programmer 24. In other embodiments, traditional batteries (e.g., nickel cadmium or lithium-ion batteries) may be used. In addition, programmer 24 may be directly coupled to an alternating current outlet to power the programmer 24. The power source 108 may includeAttorney Docket: A0013968W001circuitry to monitor power remaining within a battery. In this manner, a user interface 104 may provide a current battery level indicator or low battery’ level indicator when the battery needs to be replaced or recharged. In some cases, power source 108 may be capable of estimating the remaining time of operation using the current battery.

[0057] FIGS. 5A-5B show the patient’s heart 12 implanted with an implantable medical electrical lead 723 coupled to an IMD 716 to deliver bundle branch pacing according to one example of an IMD system 710. FIG. 5B is a close-up view of lead 723 in the patient’s heart 12 of FIG. 5A. In some embodiments, the electrical lead 723 may be the only lead implanted in the heart 12, e.g., passed from the RA through the tricuspid valve (TV) into the RV and further into the ventricular septum (VS). In other embodiments as discussed herein, there may be multiple leads implanted in the heart 12. The one or more implantable electrodes may include a pacing electrode implantable proximate the cardiac conduction system or may be implantable in the ventricular septum (VS), to deliver cardiac conduction system pacing (CSP) therapy, for examples.

[0058] In one embodiment, the lead 723 may be configured for dual bundle branch pacing, and the lead 723 may be the same as or similar to lead 18 shown in FIG. 2) except that the lead 723 is implanted near the bundle branches in the ventricular septum (VS) from the right ventricle 28 distal to, for example, the His bundle 13. As illustrated, the lead 723 is implanted in the septal wall, or ventricular septum, from the right ventricle 28 toward the left ventricle 32. The lead 723 may not pierce through the interventricular septum into the left ventricle 32 or extend into the left ventricular chamber. An electrode 752 and a tissue-piercing electrode 761 may be disposed on a distal end portion of the lead 723, which may also be described as a shaft. The electrode 752 may be configured to sense or pace the right bundle branch (RBB) area and the electrode 761 may be configured to sense or pace the left bundle branch (LBB) area, for example, during dual bundle branch pacing. Accordingly, the electrode 752 may be implanted near right bundle branch 8b, and the electrode 761 may be implanted near the left bundle branch 8a. The electrode 761 may be described as a unipolar cathode electrode, which may be implanted on the left side of the patient's ventricular septum. The electrode 752 may be described as a unipolar cathode electrode, which may be implanted on the right side of the patient’s ventricular septum.

[0059] During dual bundle branch pacing, both the electrode 752 and the electrode 761 may each deliver a cathodal pulse to achieve synchronized activation, or excitation, of the right bundle branch 8b and the left bundle branch 8a, which may result in synchronized activation of the right ventricle 28 and the left ventricle 32. In some embodiments, the pulses may be delivered at the same time to achieve synchrony. In other embodiments, the pulses may be delivered with a delay to achieve synchrony. In other examples, one electrode 752 or 761 may serve as an anode and theAttorney Docket: A0013968W001other electrode 761 or 752 may serve as a cathode in a bipolar electrode pair to deliver dual bundle branch pacing with both cathodal and anodal capture of the bundle branches or fascicles thereof. At other times, LBB area pacing (LBBAP) may be delivered using electrode 761 as a cathode electrode paired with electrode 752 as a return anode or the IMD housing can or case electrode as the return anode (or any other available return anode). In still other instances, RBB area pacing (RBBAP) may be delivered using electrode 752 as a cathode electrode paired with electrode 761 as a return anode or the IMD housing can or case electrode as the return anode (or any other available return anode).

[0060] Although the lead 723 as shown in configured for dual bundle branch pacing using the electrodes 752, 761, it is to be understood that the lead 723 or leads similar thereto are considered herein that may only include one of the electrode 752 and the electrode 761, and thus, only configured to deliver cardiac conduction system pacing therapy to one of the right bundle branch or the left bundle branch.

[0061] Additionally, the lead 723 may include a right atrial electrode 770 disposed more proximal to the electrode 752 and the electrode 761 along the lead 723. The right atrial electrode 770 may be positioned in or near the right atrium 26 and may function as an anode for cathodal pulses from the electrode 752 and / or the electrode 761. Further, the right atrial electrode 770 may provide atrial sensing to, e.g., sense atrial depolarizations or activations, to sense or detect atrial fibrillation, etc. Although the lead 723 as shown includes the right atrial electrode 770. it is to be understood that the lead 723 may not include the right atrial electrode 770, and instead, only include one or both of the electrode 752 and the electrode 761.

[0062] It will be appreciated that the systems and device of this application can include any combination of leads shown in the above systems. For example, a system configured to provide LV-only pacing, conduction system pacing (e.g., LBBAP) only, and CSP in combination with LV pacing can include a lead configured to be engaged with the conduction system (e.g., a lead configured to stimulate the left bundle branch) and a lead configured to stimulate the left ventricle.

[0063] FIG. 6 is a diagram of an IMD system 10’ having RV lead 18 implanted in an interventricular septal location for delivering CSP instead of along the RV apex as shown in FIG.1. IMD 16 is shown connected to RA lead 22 and LV coronary sinus lead 20 as generally described above in conjunction with FIGs. 1 and 2. RA lead 22 is implanted to position electrodes 48 and 50 in the RA for sensing an atrial electrical signal (referred to as an “atrial EGM” signal for the sake of convenience) and delivering atrial pacing pulses. LV coronary sinus lead 20, also referred to herein as “LV lead” 20, may be advanced into the RA and coronary sinus ostium 11 to advance LV lead 20 along the coronary sinus and into a cardiac vein, for example,Attorney Docket: A0013968W001along the lateral free wall of the LV. In this location, LV lead electrodes 44, 45, 46 and / or 47 can be selected by circuitry’ within IMD 16 (e.g., as described above in conjunction with FIG. 3) for sensing an LV electrical signal (referred to as an “LV EGM” signal for the sake of convenience) and / or delivering LV pacing pulses for pacing the LV from a myocardial pacing location, e.g., during an LV-only pacing configuration or during aLOT-CRT pacing configuration.

[0064] In this example, the distal end of lead 18 is advanced from the RV into the interventricular septum 9 to position the distal electrode 42 in the vicinity of the LBB or a fascicle thereof. Ring electrode 40 may be positioned in the vicinity' of the RBB or a fascicle thereof in some examples. As generally described above in conjunction with FIG. 5, a bipolar pacing electrode pair, e.g., electrodes 42 and 40 of lead 18, may be positioned within the interventricular septum 9 for delivering LBBAP, RBBAP or dual bundle branch pacing. As such, IMD system 10’ is configured to deliver CSP to one or both bundle branches or fascicles thereof. IMD system 10’ may deliver a combination of CSP plus LV myocardial pacing via lead 18 and LV lead 20, e.g., during LOT-CRT, CS-only pacing via lead 18, or LV-only pacing via lead 20. Any of the CSP-only, LV-only pacing or LOT-CRT ventricular pacing configurations can be delivered in combination with atrial pacing delivered by RA lead 22 using an optimized AV pacing delay, which may be an optimized PAV pacing delay. When intrinsic P-waves are sensed from the atrial EGM signal sensed via RA lead 22, the LV-only pacing, CSP-only, or LOT-CRT pacing may be delivered by timing the ventricular pacing pulses at SAV pacing delays from the sensed P-waves.

[0065] FIG. 7 is a diagram of an IMD system 10” that may be configured to deliver cardiac pacing therapy according to the techniques disclosed herein in yet another example. The IMD system 10” may include IMD 16 and a co-implanted leadless IMD 114. In some examples, electrodes positioned for delivering the LV-only, CSP-only, or LOT-CRT pacing configurations may include electrodes that are not necessarily carried by a medical electrical lead. Furthermore, the IMD system may be a multi-device system, e.g., two co-implanted IMDs, operating cooperatively to deliver ventricular pacing according to a selected pacing configurations and switch between different pacing configurations, such as LV-only. CSP-only or CSP plus LV myocardial pacing, e.g., LOT-CRT. To coordinate cardiac pacing according to different pacing configuration selections, IMD 16 and IMD 114 may be configured to communicate with each other by wireless radiofrequency communication, e.g., BLUETOOTH® or other communication protocol, or via tissue conduction communication (TCC) in which communication signal pulses are transmitted as electrical pulses that are conducted between IMD 16 and IMD 114 via the body fluids and tissues. The electrical pulses are transmitted at a frequency and pulse energy that is unlikely to capture or stimulate cardiac, nerve or muscle tissue. TCC signals may beAttorney Docket: A0013968W001transmitted and received using the electrodes that are used for sensing and / or pacing, e.g., any of the electrodes carried by leads connected to IMD 16 and electrodes 118, 120 and / or 122 of IMD 114.

[0066] IMD 114 is a leadless pacemaker that may be implanted wholly within a heart chamber or on a heart chamber (e.g., epicardially) for sensing cardiac signals and delivering cardiac pacing pulses. IMD 114 is shown implanted in the RA for delivering atrial pacing and delivering ventricular pacing from a right atrial approach according to some examples. IMD 114 may be positioned for delivering ventricular pacing pulses via the heart’s native conduction system and / or interventricular septal tissue from the RA approach. The distal end 112 of IMD housing 115 may be positioned at the inferior end of the interatrial septum, beneath the AV node and near the tricuspid valve (TV) annulus to position a distal tip electrode 116 for advancement into the interatrial septum toward the His bundle (shown in FIG. 5B) of the native His-Purkinje conduction system. The distal tip electrode 116 of IMD 114 may be positioned generally in the area of the Triangle of Koch, for advancement into the interatrial septum toward the His bundle, for example for delivering ventricular pacing pulses in the area of the His bundle and / or to the interventricular septal tissue.

[0067] IMD 114 includes a housing 115 having a longitudinal sidewall 117 extending between distal end 112 and proximal end 113 of IMD 114. IMD 114 may be anchored at the implant site by a helical fixation member 126 to place distal tip electrode 116. which may be an uninsulated portion of the distal end of helical fixation member 126, in the area of the His bundle, for example, for delivering CSP pulses in a selected ventricular pacing configuration. In other examples, IMD 114 may be provided with other t pes of fixation members, e.g., tissue piercing fixation tines, barbs, a fish hook shaped member, etc. In the examples shown, the proximal portion of helical fixation member 126 may be coated with an electrically insulative coating. Distal tip electrode 116 may be an uninsulated distal portion of helical member 126 to sen e as a cathode electrode for sensing ventricular EGM signals and / or delivering ventricular pacing pulses as CSP pulses that capture the His bundle or a portion thereof. Distal tip electrode 116 may be used with proximal ring electrode 118 as the return anode for delivering ventricular pacing pulses and sensing ventricular electrical signals, e.g., for sensing R-waves. The proximal ring electrode 118 may circumscribe a proximal portion of housing 115 or be positioned on the proximal end 113 of housing 115 in other examples.

[0068] IMD 114 may be configured to sense atrial electrical signals for sensing P-waves. For example. IMD 114 may have a second distal electrode 120 that may be earned near, on or extend from distal end 112 of housing 115. Distal electrode 120 can be used in combination with the proximal ring electrode 118 for sensing atrial P-waves and delivering atrial pacing pulses. InAttorney Docket: A0013968W001other examples, IMD 114 may include one or more electrodes (not shown) on distal end 112 that can be selected in an atrial pacing electrode vector for delivering atrial pacing pulses. In some examples, a second ring electrode (not shown) may be provided along the lateral sidewall 117 of IMD 114 to serve as the return anode in a dedicated atrial pacing / sensing electrode vector with atrial cathode electrode 120. Various electrode arrangements provided on a leadless IMD may include one or more electrodes located along the longitudinal sidewall 117 of housing 115. one or more electrodes on distal end 112 or extending therefrom, and / or one or more electrodes on proximal end 113 or extending therefrom. The techniques disclosed herein are not limited to a particular electrode configuration and other ty pes and arrangements of electrodes for sensing cardiac electrical signals and delivering cardiac pacing according to the techniques disclosed herein may be used.

[0069] IMD 114 may be configured to provide single chamber ventricular pacing with dual chamber (atrial and ventricular) sensing. IMD 114 may be configured to deliver dual chamber atrial and ventricular pacing, e.g., using an optimized SAV and / or PAV pacing delay. In this way, IMD 114 may operate to deliver CSP-only. IMD 16 may operate to deliver LV-only pacing via LV lead 20. However, IMD system 10” may be configured to deliver LOT-CRT, e.g., the combination of CSP and LV myocardial pacing, by coordinating the delivery' of CSP pulses by7IMD 114 and LV myocardial pacing pulses via IMD 16 in a manner that improves ventricular electrical and mechanical synchrony.

[0070] IMD 114 may include a cardiac mechanical signal sensor, e.g., an accelerometer or other motion sensor, pressure sensor, impedance sensor, acoustic sensor, or impedance sensing circuitry, for sensing cardiac mechanical activity' signals which may be used by IMD system 10” in assessing one or more hemodynamic or other parameters for selecting a ventricular pacing configuration, e.g.. LV-only, CSP-only, or CSP plus LV myocardial pacing (e.g., LOT-CRT). as further described below.

[0071] To coordinate ventricular pacing in the CSP plus LV myocardial pacing configuration, for example, IMD 114 may be configured to transmit a communication signal to IMD 16 in timed relation to a delivered atrial pacing pulse, a sensed P-wave, a delivered CSP pulse, and / or a sensed R-w'ave. IMD 16 may receive the transmitted communication signal and deliver an LV myocardial pacing pulse using a selected pacing electrode vector from among electrodes 44, 45, 46, 47 or housing electrode 58 in response to receiving the communication signal. In this w ay, an LV pacing pulse can be delivered in timed relation to an atrial electrical event (e.g., at an SAV or PAV pacing delay) and / or in timed relation to a CSP pulse delivered by IMD 114. IMD 16 may¬ transmit a communication signal to IMD 114 in timed relation to a scheduled or delivered LV pacing pulse. IMD 114 may respond to the communication signal by delivering a CSP pulse inAttorney Docket: A0013968W001timed relation to the received communication signal. Processing circuitry included in IMD 114 and / or IMD 16 may perform pacing configuration assessments as further described below for selecting a pacing configuration. IMD 114 and IMD 16 may be configured to communicate to select CSP-only by IMD 114, LV-only pacing by IMD 16, or CSP plus LV pacing (e.g., LOT-CRT) cooperatively delivered by IMD 114 and IMD 16 in accordance with the pacing configuration selection techniques described herein.

[0072] IMD 114 is shown implanted in a position for delivering CSP from a right atrial approach in FIG. 7, but it is to be understood that IMD 114 may be implanted in other locations for delivering CSP. For example, IMD 114 may be implanted in the RV to advance distal tip electrode 116 into the interventricular septum 9 to the vicinity of the LBB or fascicles thereof for delivering LBBAP. Helical fixation member 126 may include a proximal, uninsulated portion that can serve as a return anode with distal tip electrode 116 serving as a cathode (or vice versa) for delivering LBBAP (or RBBAP or dual bundle branch pacing) in some examples. As such, electrodes implanted for delivering ventricular pacing pulses to a CSP site may be carried by a medical electrical lead, e.g., lead 723 shown in FIG. 5A and FIG. 5B. or carried by the housing of a leadless IMD, e.g., IMD 114. In still other examples, instead of positioning leadless IMD 114 for delivering pacing pulses in the area of the His bundle from a right atrial approach, a medical electrical lead, e.g., lead 18 shown in FIG. 1 or lead 723 shown in FIG. 5A, may be advanced into the RA so that a tip electrode, e.g., electrode 42 or electrode 761 shown in FIG. 2 or FIG. 5B, respectively, can be advanced toward the area of the His bundle from the Triangle of Koch, as generally described above. The lead 18 or 723 may be connected to IMD 16 for use in delivering CSP pulses in the CSP-only pacing configuration and / or during CSP plus LV myocardial pacing (e.g., LOT-CRT).

[0073] The lead 18 or 723 may include atrial sensing and pacing electrodes for facilitating atrial sensing and pacing as well as ventricular sensing and CSP delivery. In other examples, RA lead 22 (shown in FIG. 1) may be implanted in the RA in combination with lead 18 or 723 carrying a tip electrode positioned in the area of the His bundle from the right atrial approach. Thus, IMD 16 may be connected to a lead for delivering CSP pacing from a right atrial approach or from a right ventricular approach and an LV lead for delivering LV myocardial pacing for delivering ventricular pacing in a selected pacing configuration from among LV-only pacing, CSP-only, or LOT-CRT pacing configurations.

[0074] LV-only pacing can be comparable to CRT for patients with left bundle branch block (LBBB) and normal atrioventricular conduction. For example, LV-only pacing may specifically target the left ventricle, which can be particularly beneficial for patients with LBBB or other left ventricular conduction delays, as it directly addresses the delayed activation of the left ventricle.Attorney Docket: A0013968W001

[0075] LBBAP is considered a potential alternative to traditional biventricular pacing (BVP) for certain heart failure patients, particularly those with significant LBBB. LBBAP can be a feasible pacing therapy alternative to delivering CRT by delivering LV myocardial pacing or biventricular (myocardial) pacing in patients with right bundle branch block (RBBB), heart failure (HF), or LV dysfunction. In some instances, LBBAP alone can improve electrical and mechanical ventricular synchrony.

[0076] CSP plus LV myocardial pacing, e.g., LOT-CRT, can be considered when optimal electrical and / or mechanical resynchronization is not achieved by LV-only pacing, LBBAP only, dual bundle branch only pacing or standard biventricular myocardial pacing (BiV-CRT) in a patient with heart failure and LBBB. Heart muscle contractions may remain poorly coordinated despite conventional CRT. potentially due to suboptimal lead placement or advanced conduction disease. In other words, LOT-CRT can be used as an alternative strategy when LV myocardial or LBBAP alone does not provide sufficient improvement in cardiac synchronization.

[0077] The devices, systems, and methods described herein can be configured to automatically select the optimal pacing configuration (example of configurations defined by the ventricular pacing site location(s): e.g., LV-only, LBBAP only (or other CSP-only), or CSP plus LV myocardial pacing (e.g., LOT-CRT). Any of the selected pacing configurations can include deli very of ventricular pacing pulses at the pacing site(s) of the selected pacing configurations at an associated AV pacing delay between atrial electrical events (sensed P-waves and delivered atrial pacing pulses) and the ventricular pacing pulses delivered to the pacing site(s)). The pacing configuration may be automatically selected based on the patient’s current status and / or to optimize the longevity of the device.

[0078] Parameters used to assess the current status of the patient can include QRS signal width, various metrics of electrical and / or mechanical cardiac dyssynchrony, morphology match, RBBB or LBBB, patient demographics, AV delay, atrial rate or rhythm (e.g., sinus rhythm, atrial fibrillation, atrial flutter), current heart rate, patient symptoms or feedback, hemodynamic metric(s) (e.g., based on heart sounds, cardiac or thoracic bioimpedance, blood pressure, oxygen saturation, cardiac motion or other cardiac mechanical activity signal), valve regurgitation metric, LBBAP capture type (e.g., deep septal, selective, non-selective), inter-ventricular conduction time, patient physical activity, time of day, ventricular arrhythmia detection or history, phrenic nerve or other extraneous nerve stimulation, lead issue (e.g., lead impedance change or out of normal range impedance, capture threshold, oversensing or non-cardiac noise, or other indication of lead dislodgement or displacement), and / or estimated longevity of IMD power source 90. Methods for performing a pacing configuration assessment, also referred to herein as “assessment,” which may include analysis of any of the foregoing examples for selecting aAttorney Docket: A0013968W001ventricular pacing configuration, also referred to herein as ‘‘pacing configuration,” are described below.

[0079] An illustrative method performed by a device or system for selecting a pacing mode or configuration based on patient status and device longevity is shown by the flow chart 300 in FIG.8. As shown in FIG. 8, the device or system can periodically make an assessment (block 302), based on one or more of the patient parameters, cardiac electrical or mechanical activity parameters, and / or device-related parameters such as device longevity, to select an optimal pacing configuration between LV-only pacing, CSP-only without LV pacing (e.g., His bundle pacing, LBBAP, RBBAP or dual bundle branch pacing), and CSP plus LV-only pacing (e.g., meaning the combination of LV pacing via an LV lead or electrodes positioned for LV myocardial pacing and CSP via a lead or electrodes positioned for CSP, also referred to herein as “LOT-CRT”).

[0080] For the sake of convenience, the flow chart 300 and other How charts presented herein are described with reference to IMD 16 shown in FIG. 3 connected to leads 18, 20 and 22 as shown in FIG. 6. However, it is to be understood that the methods and techniques described herein for automatically selecting a pacing configuration may be implemented in any of a number of IMD systems, including any of the examples described above in conjunction with FIGs. 1-7. Control module 81 may perform the assessment at block 302 by determining one or more parameters from sensed cardiac electrical signals, from sensed cardiac mechanical signals, from a patient physical activity signal, and / or other signals sensed by the IMD system.

[0081] The assessment performed at block 302 may be performed by analyzing one or more signals sensed by the IMD during cardiac pacing delivery' by therapy delivery' module 84 according to the currently selected pacing configuration (e.g., LV-only pacing, CSP-only, or LOT-CRT). The assessment may include analyzing one or more signals sensed by the IMD during cardiac pacing delivery by therapy delivery module 84 according to a pacing configuration that is different than the currently selected pacing configuration. For example, if IMD 16 is currently delivering LV-only pacing at the time of the assessment, control module 81 may control therapy delivery module 84 to deliver cardiac pacing according to a CSP-only configuration and / or a LOT-CRT configuration during the assessment in addition to the LV-only pacing, e.g., in sequential test pacing configurations. The assessment may include analyzing one or more signals sensed by the IMD 16 (or the IMD system) during cardiac pacing delivery by therapy delivery module 84 according to each of the selectable pacing configurations, e.g., LV-only pacing (without CSP), CSP-only without LV myocardial pacing, and LOT-CRT.Additionally or alternatively, the assessment performed at block 302 may include analyzing one or more signals sensed by IMD 16 during an intrinsic ventricular rhythm (e.g., no LV pacing andAttorney Docket: A0013968W001no CSP). The atria may or may not be paced by IMD 16 during the assessment of the intrinsic ventricular rhythm. For the sake of illustration in the description that follows, the CSP plus LV myocardial pacing configuration (which can include one or more CSP sites and one or more LV myocardial pacing sites) is referred to hereafter as “LOT-CRT).

[0082] The assessment performed at block 302 may additionally or alternatively include determining one or more device-related and / or lead / electrode-related metrics, e.g., by performing device / system diagnostic tests. The assessment may include measuring the remaining voltage of power source 90, determining a predicted time to end of life (EOL) of power source 90, performing electrode / lead impedance measurements, performing capture threshold tests for determining the pacing capture threshold at one or more pacing sites of the available ventricular pacing configurations, etc.

[0083] In some examples, the assessment performed at block 302 may include receiving, e.g., via user interface 104 (of programmer 24 in FIG. 4) and / or telemetry module 88, patient (or caregiver) reported data, which may report symptoms and / or wellness or other clinical assessments during the currently selected pacing configuration and / or during each pacing configuration tested during the assessment. Patient reported data may include qualitative, semi-quantitative and / or quantitative patient-related data that represents the patient’s activity, sleep, heart failure symptoms, heart failure symptom severity, and / or overall feeling of wellbeing. In some examples, the assessment performed at block 302 may include receiving patient-related data from an external device, such as programmer 24 or a patient-wom fitness or activity tracker, patient weighing scale or other BLUETOOTH® or communication-enabled patient monitoring device.

[0084] At block 304, control module 81 may determine if one pacing configuration is clearly optimal, e.g.. based on one or more signals of cardiac electrical activity, one or more signals of cardiac mechanical activity and / or patient feedback. In some instances, the optimal pacing configuration may be identified at block 304 based on device-related diagnostics such as lead or electrode impedance measurements, remaining battery voltage of power source 90 or predicted EOL. time of day or scheduled time periods, and / or patient-related conditions such as patient heart rate or physical activity level, as further described below.

[0085] If one configuration is not clearly optimal (“no” branch of block 304), e.g., based on one or more metrics of electrical and / or mechanical cardiac synchrony or other conditions as further described below, control module 81 may select a pacing configuration that optimizes the IMD system longevity at block 306. e.g., by selecting the pacing configuration that requires less energy to deliver the ventricular pacing pulses than other available pacing configurations. ForAttorney Docket: A0013968W001example, the pacing configuration associated with the lowest pacing capture threshold and / or fewest number of ventricular pacing sites may be selected at block 306.

[0086] If one pacing configuration is clearly optimal (“yes” branch of block 304), e.g., based on one or more metrics of electrical and / or mechanical synchrony, control module 81 may select the pacing configuration deemed most optimal at block 308. For example, control module 81 may perform the assessment at block 302 by determining one or more metrics of electrical and / or mechanical synchrony from cardiac signals sensed during each pacing configuration being tested. Based on a comparative analysis of the determined metrics, a single pacing configuration may be determined to be clearly optimal, e.g., greatest improvement in an electrical synchrony metric and / or greatest improvement in a mechanical synchrony metric relative to the other pacing configurations tested and / or relative to the intrinsic ventricular rhythm.

[0087] The assessment may be performed at block 302 on a scheduled basis, e.g., bidaily, daily, weekly, monthly or other programmed frequency of assessment. In some examples, the assessment may additionally or alternatively be performed in response to a manual command entered via user interface 104 (FIG. 4), which may be received by telemetry module 88.Additionally or alternatively, the assessment may be performed at block 302 in response to a triggering condition. For example, control module 81 may perform various device diagnostic testing and / or patient monitoring testing on a daily basis (or at other scheduled intervals). As illustrative examples, control module 81 may perform lead / electrode / device diagnostic testing that can include lead / electrode impedance measurements, pacing capture threshold determinations, battery voltage measurement, and predicted power source EOL determination. Control module 81 may determine one or more cardiac electrical activity monitoring metrics such as a heart rate profile, heart rate variability, QRS morphology analysis, conduction time determinations, electrical activation time determinations and / or other cardiac electrical activity metrics. Control module 81 may determine one or more cardiac mechanical activity monitoring metrics such as a bioimpedance measurements, heart sound intervals (e.g., S1-S2 heart sound interval), heart sound amplitude, blood pressure metrics, oxygen saturation measurement, and / or other cardiac mechanical activity metrics of cardiac function. Control module 81 may determine other patient monitoring metrics such as a daily patient physical activity profile, which may be determined from a patient physical activity sensor, and / or fluid status, which may be determined by monitoring intrathoracic impedance changes. Control module 81 may trigger the assessment at block 302 if a trend or change in a device diagnostic test result meets a threshold change or level. Control module 81 may trigger the assessment at block 302 if a trend or change in a cardiac electrical activity’ monitoring metric meets a threshold change or level. Control module 81 may trigger the assessment at block 302 if a trend or change in a cardiac mechanical activity7Attorney Docket: A0013968W001monitoring metric meets a threshold change or level. Control module 81 may trigger the assessment at block 302 if a trend or change in a patient monitoring metric meets a threshold change or level.

[0088] FIG. 9 is a flow chart 400 of a method for controlling the ventricular pacing configuration for delivering a cardiac pacing therapy by an IMD or IMD sy stem according to another example. At block 402, control module 81 may control therapy delivery’ module 84 to deliver ventricular pacing in a CSP-only pacing configuration or in an LV-only pacing configuration. For example, LBBAP may be delivered in a patient having HF with some degree of LBBB and / or AV conduction block. LBBAP may promote improvements in ventricular synchrony by delivering ventricular pacing pulses at an SAV or PAV pacing interval that captures the LBB for correcting the LBBB and causing ventricular depolarization along the native conduction system pathways. In a patient having HF with normal AV conduction, LV-only pacing may be delivered to improve ventricular synchrony. For instance, LV pacing pulses may be delivered at an SAV or PAV pacing interval to promote fusion of the pacing evoked response at the LV myocardial pacing site with the intrinsically conducted R-wave, thereby promoting improved ventricular synchrony. A clinician may select the initial pacing configuration to be LBBAP or LV-only pacing, for example, based on patient evaluation and individual patient need. In other examples, the initial pacing configuration may be a default pacing configuration, e.g., LBBAP or LV-only pacing, and may be switched automatically by control module 81 based on the first pacing configuration assessment. A combination of CSP plus LV pacing, e.g., delivered as LOT-CRT, may be selected initially in some instances. However, in order to conserve the IMD power source 90, pacing only at a CSP site or pacing only at an LV myocardial pacing site may be selected as the initial pacing configuration rather than pacing at both a CSP site and an LV myocardial pacing site.

[0089] For the sake of example, the CSP-only configuration is referred to as LBBAP in the flow chart 400 of FIG. 9. However, it is to be understood that the CSP-only configuration may be RBBAP if the patient experiences RBB block or dual bundle branch pacing of both the RBB and LBB, e.g., by adjusting the pacing electrode vector and pacing output to cause both cathodal and anodal capture or by delivering both RBBAP and LBBAP using two cathode electrodes positioned in the interventricular septum (each paired with an anode electrode carried by a lead coupled to IMD 16 or housing electrode 58). In still other examples, the CSP-only configuration may be His bundle area pacing targeting capture of the His bundle or at least a portion or branch thereof, x The CSP-only configuration may include multiple CSP sites and is not limited to being a single CSP site. The CSP-only configuration can result in myocardial pacing when non-selective capture of the targeted portion of the conduction system causes a pacing-evoked depolarization of both the conduction system tissue and surrounding myocardial tissue. However,Attorney Docket: A0013968W001the CSP-only configuration is delivered without delivering pacing pulses to another ventricular pacing site that is targeting myocardial tissue at a location away from the ventricular conduction system, e.g., away from the His bundle, LBB or RBB such as along the LV lateral free wall.

[0090] It is noted that in selecting an LV-only pacing configuration or an CSP-only configuration, control module 81 and therapy delivery module 84 in combination with sensing module 86 may perform a capture threshold search to determine the pacing capture threshold associated with one or more available pacing electrode vectors operatively implanted at the CSP or LV myocardial pacing sites. More than one cathode and anode pair may be tested for determining a pacing electrode vector that successfully captures the targeted pacing site with a lowest capture threshold. It is further noted that multiple AV pacing delays may be tested to determine the SAV pacing delay and / or PAV pacing delay used by pacer timing and control module 87 for scheduling the ventricular pacing pulses to be delivered according to the selected pacing configuration. An AV pacing delay may be determined, for example, by determining intrinsic AV conduction times, interventricular conduction times and / or QRS width or other ventricular synchrony metric to promote electrical synchrony between the ventricles and in some cases fusion between the pacing evoked depolarization and an intrinsically conducted R-wave. Thus, therapy delivery module 84 may be controlled by control module 81 to deliver ventricular pacing according to the selected pacing configuration of LV-only pacing or LBBAP only (or other CSP-only configuration) using a pacing pulse output, pacing electrode vector, and / or AV pacing delay that are determined by control module 81 through capture threshold testing and / or AV pacing delay optimization procedures.

[0091] At block 404, processing circuitry of the IMD system may establish a morphology template of the QRS waveform sensed from a ventricular EGM signal sensed by sensing module 86 during the selected pacing configuration, e.g., with optimized AV delay and capture verification at the targeted pacing site. The process of establishing the QRS waveform morphology template may be performed by IMD control module 81, e.g., processor 80, or by programmer processor 100, which may be configured to receive the ventricular EGM signal transmitted from IMD 16 to programmer 24 in some examples. The established morphology template data may be transmitted back to IMD 16 for storage in memory 82. The QRS waveform morphology (also referred to herein as “QRS morphology”) is representative of the electrical activation of the ventricles due to the capture ty pe and capture timing. For instance, if LBBAP is being delivered (with no LV myocardial pacing), at least a portion of the LBB may be captured with or without septal myocardial capture (non-selective CSP capture or selective CSP capture, respectively). If the capture threshold changes over time or the electrode location changes, e.g., due to lead shifting or dislodgment, the QRS morphology7may change if the capture ty peAttorney Docket: A0013968W001changes, e.g., from selective LBB capture to non-selective LBB capture or to deep septal capture of the septal myocardial tissue only without LBB or RBB capture or to selective or non-selective RBB capture. The QRS morphology may change over time with disease progression or remodeling or other factors as well. The QRS morphology is one cardiac electrical activity metric that may be monitored and assessed over time for use in controlling the pacing configuration that is selected by control module 81 for delivering ventricular pacing.

[0092] The QRS morphology template may be established at block 404 by acquiring the postpace waveform from the ventricular EGM signal sensed by sensing module 86 during a template window during one or more paced ventricular beats. The template window may have a start time and an end time relative to the delivered ventricular pacing pulse immediately preceding the template window. The start time and end time may be stored in memory 82. The template window may have a specified start time between 4 ms and 100 ms after the ventricular pacing pulse (delivered according to the selected pacing configuration) or between 30 ms and 75 ms after the ventricular pacing pulse as examples. In one example, the default template window start time is about 45 to 50 ms after the ventricular pacing pulse or 12 sample points of the EGM signal (when sampled at a 256 Hz sampling rate) after the ventricular pacing pulse. The template window may have an end time that is 200 to 350 ms after the ventricular pacing pulse or between 225 and 275 ms after the ventricular pacing pulse as examples. In an illustrative example, the template window extends from a start time of 48 ms to an end time of 240 ms after the ventricular pacing pulse.

[0093] The processing circuitry may verify that template beat requirements are met before using a post-pace waveform in generating the template. The processing circuitry may verify that the post-pace waveform meets template beat requirements when both the immediately preceding ventricular cycle is a paced beat and the immediately subsequent ventricular cycle is a paced beat and when the ventricular cycle length (VCL) ending with the ventricular pacing pulse followed by the post-pace waveform and the VCL beginning with the ventricular pacing pulse followed by the post-pace waveform are within a threshold difference of each other, e.g., within 50 to 100 ms of each other. Additionally or alternatively, the processing circuitry may determine that the template beat requirements are met when a morphology match score of the post-pace waveform matches at least one preceding post-pace waveform and / or at least one subsequent post-pace waveform with a match score of at least 60, 70, 80 or other specified match threshold (with possible match scores ranging from 0 to 100). Methods for determining a match score between two waveforms is further described below. Additionally or alternatively, the processing circuitry may determine that template beat requirements are met based on user input (e.g., via user interface 104 of programmer 24). For example, a clinician may select one or more post-paceAttorney Docket: A0013968W001waveforms that are displayed by programmer 24 to be used as template beats by the processing circuitry for establishing the template.

[0094] In some examples, the processing circuitry may acquire multiple post-pace waveforms from consecutively paced ventricular cycles during the initially selected pacing configuration and may establish the morphology template from an ensemble average of the multiple post-pace waveforms. The process of establishing the morphology’ template may include determining wavelet transform coefficients that represent the post-pace waveform of the template. In some examples, a Haar wavelet transform is employed to represent the template waveform by the transform wavelet coefficients, which may include weighting contributions of certain time-scales of the wavelet transform coefficients, e.g.. to emphasize wider scale wavelet transform coefficients relative to narrower scale wavelet transform coefficients. In this way, the contribution of noise or insignificant EGM waveform information in the template can be reduced in the resulting wavelet transform. The morphology7template stored in memory’ 82 including the wavelet transform coefficients can be compared to other post-pace waveforms sensed during ventricular pacing according to the selected pacing configuration, other available pacing configurations and / or the intrinsic ventricular rhythm during pacing configuration assessments as further described below.

[0095] Example methods of performing a Haar w avelet transform to obtain signal w avelet coefficients that can be compared between a template representing an intrinsic sensed R-wave and an unknown waveform sensed during an intrinsic cardiac rhythm are generally disclosed in U.S. Patent No. 6,393,316 (Gillberg, et al., filed May 8, 2000) and in U.S. Patent No. 8,521,268 (Zhang, et al., filed May 10, 2011), the entire content of both patents incorporated herein by reference. These methods for determining wavelet transform coefficients for comparing sensed intrinsic QRS waveforms may be adapted for use in the methods disclosed herein for obtaining w avelet transform coefficients of a post-pace QRS morphology template during ventricular pacing according to a selected ventricular pacing configuration. For example, different weighting may be applied to the wavelet transform coefficients determined from post-pace waveforms than the weighting applied to an intrinsic sensed waveform. Furthermore, the template window over which the post-pace waveforms are obtained can be defined by a start time relative to the ventricular pacing pulse that excludes post-pace signal artifact that occurs relatively early after the pacing pulse.

[0096] At least one wavelet transform representation of the QRS morphology template may be determined for storage in memory 82 at block 404. In some examples, the template may be shifted one or more sample points left or right (in time) with respective wavelet transform representations determined for each time-shifted template. For instance, the wavelet transformAttorney Docket: A0013968W001coefficients may be calculated for each time-shifted template so that three sets of wavelet transform coefficients (which may each be filtered and normalized) may be stored in memory 82, to represent the shape of the template.

[0097] In some examples, other template features may be determined and stored at block 404 in addition to (or alternatively to) the wavelet transform coefficients. For example, the maximum absolute peak amplitude of the template and its polarity (positive or negative) may be determined and stored in IMD memory 82. The peak time of the maximum absolute peak amplitude may be determined as the time interval from the immediately preceding ventricular pacing pulse to the sample point having the maximum absolute peak amplitude. In other examples, the maximum peak amplitude of a specified polarity, positive or negative, may be determined and stored along with its corresponding peak time.

[0098] In some examples, the morphology template established at block 404 may include a representative amplitude of the template sample points spanning the template window. The representative amplitude may be a mean, median or summed amplitude of the rectified sample points in some examples. The mean template amplitude may be used for detecting suspected baseline shifts of a subsequent post-pace waveform that is acquired and being compared to the QRS morphology template. The baseline shift could lead to low morphology match scores without performing a vertical adjustment of the post-pace w aveform to correct for pacing artifact baseline shifts of the EGM signal.

[0099] In some examples, a feature of the QRS morphology template that is correlated to left ventricular activation time (LVAT) may be determined as the time from a ventricular pacing pulse to the maximum peak amplitude of the template w aveform or to a maximum slope of a difference signal determined from the template waveform. In still other examples, a center of area of the template or a specified portion of the template may be determined. The time interval from the ventricular pacing pulse to the timepoint of the center of area may be determined by the processing circuitry as the LVAT of the QRS morphology template and stored in IMD memory 82. A specified portion of the QRS morphology template from which the timepoint of the center of area may be determined may extend from a specified percentage or fraction of the maximum absolute amplitude (e.g., 1 / 8 of the maximum amplitude) to the maximum absolute amplitude, for example.

[0100] As such, control module 81 (and / or other processing circuitry' of the IMD system) may establish the QRS morphology template for the currently selected pacing configuration by storing in IMD memory 82 the digitized template waveform, the wavelet coefficients, a representative peak amplitude, a representative template window amplitude, an LVAT, and / or other specified feature(s) of the QRS waveform morphology7.Attorney Docket: A0013968W001

[0101] At block 406, control module 81 may perform a pacing configuration assessment. As described above, a pacing configuration assessment may be performed upon IMD implantation, periodically on a scheduled basis, in response to a manual trigger (e.g., a communication signal command received via telemetry module 88), and / or when an assessment trigger condition is detected. For example, control module 81 may perform a daily capture threshold test, daily comparison of a post-pace waveform to the established morphology’ template, daily fluid status test, or daily lead impedance test. If a threshold change from a previous test or sudden change in a trend of daily (or other periodic) tests is detected by control module 81, a pacing configuration assessment may be triggered at block 406.

[0102] In some examples, the control module 81 may determine the daily patient physical activity profile from a patient activity sensor included in sensing module 81. For instance, an accelerometer or other motion sensor or a respiration sensor (e.g., impedance sensor) may be used to monitor patient physical activity throughout the day, e.g., for controlling rate response pacing rate. Control module 81 may determine the percentage of time the patient is at a nonresting level of physical activity or how much time the rate response pacing rate is greater than the programmed lower pacing rate or greater than an activities of daily living rate, as examples. If control module 81 detects a decrease in the percentage of time out of a given day or week that the patient is at a non-resting physical activity level compared to a previous day, week or historical percentage of non-resting time, control module 81 may trigger a pacing configuration assessment at block 406.

[0103] Control module 81, therapy delivery module 84 and sensing module 86 may cooperatively perform the pacing configuration assessment at block 406 by determining one or more cardiac electrical activity metrics, determining one or more cardiac mechanical activity¬ metrics, determining one or more patient-related metrics and / or determining one or more lead / device-related metrics. The various metrics determined from signals sensed by IMD 16 may be determined during pacing according to the currently selected pacing configuration, one or more different pacing configurations and / or during an intrinsic ventricular rhythm. Example methods for performing a pacing configuration assessment are described below in conjunction with FIG. 11. A comparative analysis of the determined metrics to historical metrics and / or between metrics determined during different pacing configurations tested during the assessment may be performed by control module 81 for detecting a pacing configuration change condition at block 408.

[0104] If no pacing configuration change condition is detected, control module 81 may keep the current pacing configuration selection at block 410. Control module 81 may wait for the next pacing configuration assessment to be performed at block 406. It is to be understood that inAttorney Docket: A0013968W001between pacing configuration assessments, IMD 16 may perform one or more cardiac monitoring, patient monitoring, or lead / device-related monitoring functions for detecting an assessment trigger condition and / or for storing data in memory 82 that may be used in performing the assessment at block 406. For example, IMD 16 may perform capture threshold searches, lead impedance measurements, determine QRS morphology match scores, determine QRS morphology features that can be compared to the QRS morphology template features established at block 404, determine a patient physical activity profile, daily heart rate profile, thoracic impedance measurements, or other monitoring functions or measurements from which data may be stored in memory' 82 for use in detecting gradual and / or sudden changes in a monitored parameter that may be evaluated as part of the pacing configuration assessment performed at block 406 and detecting a pacing configuration change condition, as further described below, e.g., in conjunction with FIG. 11.

[0105] If control module 81 detects a pacing configuration change condition at block 408, control module 81 may switch from the current pacing configuration to a different pacing configuration at block 412. In some examples, control module 81 may switch the pacing configuration from LBBAP (or other CSP-only configuration) to LV-only pacing, from LV-only pacing to LBBAP only (or other CSP-only configuration), or from the current pacing configuration to combined CSP plus LV pacing configuration (e.g., LOT-CRT pacing configuration).

[0106] Ater switching to anew pacing configuration at block 412, control module 81 may reestablish a QRS morphology template at block 404, as generally described above, for the new pacing configuration. The new morphology template may be used in detecting a pacing configuration assessment trigger condition (e.g., a change in morphology match score or change in LVAT) and / or performing the pacing configuration assessment as described below.

[0107] FIG. 10 is a flow chart 500 of a method for controlling the pacing configuration by an IMD or IMD system according to another example. Therapy delivery module 84 may be controlled by control module 81 to deliver ventricular pacing at a CSP site, in a CSP-only pacing configuration such as LBBAP as shown in block 502, or at an LV myocardial pacing site in an LV-only pacing configuration at block 502. At block 504, processing circuitry of the IMD system may establish a QRS morphology template, e.g., according to the examples described above in conjunction with FIG. 9.

[0108] During delivery of ventricular pacing according to the selected pacing configuration, control module 81 may’ detect a LOT-CRT trigger condition. Control module 81 may detect a cardiac or patient condition during which LOT-CRT, coordinated pacing of both a CSP site and an LV myocardial pacing site, may achieve greater ventricular synchrony and ejection efficiency,Attorney Docket: A0013968W001than a CSP-only or LV-only pacing alone. In some examples, control module 81 may be configured to detect atrial arrhythmias, e.g., atrial tachycardia, atrial flutter or atrial fibrillation, and detect a LOT-CRT trigger condition in response to detecting the atrial arrhythmia. An atrial arrhythmia or supraventricular tachyarrhythmia (SVT) detection algorithm may be implemented in control module 81 and may include determining sensed PP intervals that are shorter than a tachyarrhythmia detection interval, determining sensed RR intervals that meet conducted atrial arrhythmia variability criteria, or other rate or interval based atrial arrhythmia detection criteria. In some examples, a fast atrial rate, e.g., above a rate threshold, may be detected as a LOT-CRT trigger condition. The fast atrial rate may be sinus tachycardia or an atrial tachyarrhythmia. In response to detecting the LOT-CRT trigger condition, control module 81 may control therapy delivery module 84 to deliver LOT-CRT pacing at block 508. For example, if LV-only pacing is being delivered at block 502, control module 81 may control therapy delivery module 84 to add delivery of pacing pulses to at least one CSP site, e.g., the area of the LBB, area of the RBB or the area of the His bundle, simultaneously with or at a coordinated interventricular (VV) time interval relative to the LV myocardial pacing pulses. When a fast atrial rate is the triggering condition, the LOT-CRT pacing pulses may not track the fast atrial rate. However, depending on the atrial rate and rhythm, the LOT-CRT pacing pulses may be delivered at an AV pacing delay from sensed P-waves and / or atrial pacing pulses. The LOT-CRT pacing may be delivered until the LOT-CRT trigger condition is no longer detected, e.g., when the atrial rate falls below the rate threshold or termination of a detected atrial tachyarrhythmia is detected.

[0109] Additionally or alternatively, control module 81 may be configured to detect AV conduction block as a LOT-CRT trigger condition at block 506. Control module 81 may detect AV conduction block by performing a periodic AV conduction test by extending the AV pacing delay for one or more cardiac cycles. If an intrinsic R-wave is not sensed by sensing module 86 during the extended AV pacing delay, control module 81 may detect AV conduction block. Control module 81 may control therapy delivery' module 84 to deliver LOT-CRT pacing for a specified time period or until the AV conduction block is no longer detected, e.g., during the next scheduled AV conduction test. In other instances, control module 81 may determine that AV conduction block is no longer detected due to a threshold number of intrinsic R-waves being sensed prior to the expiration of the AV pacing delay (causing inhibition of scheduled LOT-CRT pacing pulses) and / or by extending the AV pacing delay occasionally during the LOT-CRT pacing and sensing an intrinsically conducted R-wave during the extended AV pacing delay.

[0110] Additionally or alternatively, control module 81 may detect a LOT-CRT trigger condition at block 506 in response to detecting termination of a ventricular tachyarrhythmia. Control module 81 may be configured to detect ventricular tachyarrhythmia according to a variety' ofAttorney Docket: A0013968W001tachyarrhythmia detection algorithms that may include analysis of sensed RR intervals, analysis of sensed PP and / or PR intervals (for discriminating ventricular tachyarrhythmia from SVT), analysis of QRS morphology, and / or other ventricular EGM signal analysis. IMD 16 may detect spontaneous termination of a non-sustained ventricular tachyarrhythmia, e.g., when a threshold number of RR intervals are longer than a tachyarrhythmia detection interval threshold. IMD 16 may detect termination of a detected ventricular tachyarrhythmia after delivering, by therapy delivery module 84, one or more therapies, e.g., anti-tachyarrhythmia pacing therapies and / or CV / DF shocks. Delivery of LOT-CRT pacing after termination of a ventricular tachyarrhythmia may support post-tachyarrhythmia recovery7by improving hemodynamics and cardiac pumping efficiency post-tachyarrhythmia. The LOT-CRT pacing may be delivered for a specified time interval, e.g.. one minute to several hours, one day, or one week, following termination of a detected ventricular tachyarrhythmia.

[0111] Additionally or alternatively, control module 81 may be configured to detect anon-resting patient activity level as a LOT-CRT trigger condition. Control module 81 may receive a patient physical activity signal from sensing module 86 for determining a patient physical activity metric. Examples of a patient physical activity signal include a motion signal, such as an accelerometer signal from which patient movement can be detected, or an impedance signal from which respiration rate can be determined. When the patient physical activity7metric meets a threshold level of activity, e.g., an activities of daily living threshold or a higher threshold corresponding to physical activity that is more strenuous the activities of daily living, control module 81 may detect a LOT-CRT trigger condition. Control module 81 may control therapy delivery module 84 to deliver LOT-CRT pacing at block 508 until the patient physical activity7metric falls below the threshold level of patient activity (or returns to a resting level of activity in some examples).

[0112] In some examples, control module 81 may be configured to determine a rate response pacing rate based on a detected patient physical activity7level. Therapy delivery module 84 may be controlled to deliver the cardiac pacing, which may include atrial pacing and / or ventricular pacing according to the selected pacing configuration, at a temporary rate response pacing rate that is faster than the programmed lower pacing rate and the intrinsic heart rate. The temporary7rate response pacing rate may be adjusted toward a target sensor indicated pacing rate determined from the patient physical activity7metric to meet the patient’s metabolic demand due to increased physical activity. As such, in some examples, control module 81 may detect the LOT-CRT trigger condition at block 506 based on a rate response pacing rate or sensor indicated pacing rate that is determined from the patient physical activity sensor signal.Attorney Docket: A0013968W001

[0113] During increased physical activity, the patient may benefit from LOT-CRT pacing compared to LV-only pacing or CSP-only alone. In some patients, a bundle branch block may arise during increased heart rate. As such, in some patients with normal bundle branch conduction at rest, the selected pacing configuration may be LV-only pacing. When a LOT-CRT trigger condition is detected as a patient physical activity7level that is greater than a threshold level and / or the rate response pacing rate or intrinsic sinus heart rate is increased to be faster than a threshold rate, e.g., 80 to 100 bpm, therapy delivery module 84 may be controlled by control module 81 to deliver LOT-CRT pacing until the activity level and / or heart rate or pacing rate fall below the respective thresholds.

[0114] Additionally or alternatively, control module 81 may detect a LOT-CRT trigger condition in response to a patient or user-initiated communication signal received by telemetry module 88 (e.g., transmitted by programmer 24). A patient may feel symptomatic and initiate the delivery7of LOT-CRT pacing by transmitting a trigger signal to IMD 16 from programmer 24 or another personal handheld device, for example.

[0115] In some examples, control module 81 may detect a LOT-CRT trigger signal in response to a specified time of day, which may be stored in memory 82 for scheduling LOT-CRT pacing time periods. In some examples, control module 81 may control therapy delivery7module 84 to deliver LOT-CRT when the patient is expected to be awake and active, e.g., daytime hours, to promote increased hemodynamic support and cardiac pumping efficiency when the patient is physically active and more perceptive of cardiac related symptoms that may otherwise occur if LOT-CRT is not being delivered. LV-only or CSP-onty pacing may be delivered when the patient is expected to be asleep or relatively inactive, e.g., during nighttime hours. LV-only or CSP-only pacing may be provided during the night when the patient is less likely to need increased hemodynamic support or experience HF symptoms, for example. Programmed times of day may be stored in memory 82 for use by control module 81 for switching to and from LOT-CRT pacing delivery7. One or more time periods, e.g., programmed “on” and programmed “off’ times of day, may be programmed in memory 82 so that LOT-CRT is delivered for one or more time periods during a given 24-hour period. For example, LOT-CRT may be duty cycled so that CSP plus LV myocardial pacing is delivered during a percentage of a 24 hour period and LV-only pacing or CSP-only7pacing is delivered when LOT-CRT is not being delivered.

[0116] While the example given above refers to LOT-CRT being delivered when the patient is expected to be awake and active and not being delivered when the patient is expected to be asleep or inactive, it is contemplated that cardiac recovery7and remodeling may be supported by delivering LOT-CRT when the patient is at rest. As such, in some examples, LOT-CRT on / off times stored in memory' 82 may include times that the patient is expected to be asleep or at rest,Attorney Docket: A0013968W001e.g., nighttime hours, and may or may not include times that the patient is expected to be awake or active. In some examples, control module 81 may detect a LOT-CRT trigger condition based on a combination specified time periods (e g., based on times of day or scheduled time intervals) and patient physical activity level, for example.

[0117] During or after LOT-CRT pacing is delivered, control module 81 may perform a scheduled or triggered pacing configuration assessment at block 510. In some examples, after the LOT-CRT trigger condition is reversed or resolved or a specified time period of LOT-CRT pacing is expired, control module 81 may switch back to the LV-only or the CSP-only pacing configuration that was in effect at the time that the LOT-CRT trigger condition was detected. Control module 81 may subsequently perform the pacing configuration assessment at block 510 at a scheduled time or in response to a triggering condition. In some examples, if LOT-CRT is triggered and delivered, control module 81 may perform the pacing configuration assessment at block 510 upon termination of the LOT-CRT pacing to determine if the pacing configuration should be switched back to the pacing configuration in effect at the time that the LOT-CRT trigger condition was detected, remain in the LOT-CRT pacing configuration or switch to a different pacing configuration.

[0118] As indicated at block 512, in some examples the pacing configuration assessment performed at block 510 may receive as input patient-related data that is entered by the patient (or another user), e.g., via programmer 24, which may be indicative of patient symptoms (e.g., qualitative or semi-quantitative indicators of patient symptoms). For example, the patient may input data indicating feeling worse, better, no change, indicating whether symptoms of dizziness, shortness of breath, fatigue, or other symptoms have been experienced since the last pacing configuration assessment or another specified time period. In some examples, patient-related data may be received from a patient-wom activity or fitness tracker, which may include activity¬ profiles and / or sleep quality profiles.

[0119] Examples of methods for performing the pacing configuration assessment at block 510 are described below in conjunction with FIG. 11. Based on the pacing configuration assessment, processing circuitry of the IMD 16 or IMD system may determine if a change in a cardiac-related (e.g., cardiac electrical activity metrics and / or cardiac mechanical activity metrics) or patient-related condition (e.g., reported symptoms, physical activity profile, etc.) is detected at block 514 that warrants a change in pacing configuration. If a change in a cardiac-related condition (e.g., a worsening in a cardiac electrical activity metric indicating increased cardiac electrical dyssynchrony and / or a worsening in a cardiac mechanical activity metric indicating reduced hemodynamic function or increased mechanical dyssynchrony) is detected, control module 81 may switch to a new pacing configuration at block 516.Attorney Docket: A0013968W001

[0120] If a change in a patient-related condition is detected at block 514 based on the pacing configuration assessment performed at block 510. control module 81 may switch the pacing configuration to a new pacing configuration at block 516. A change in a patient-related condition that may be detected by control module 81 warranting a change in the pacing configuration may be a worsening of patient symptoms (as input by the patient at block 512) or a decline in patient physical activity level profile or rate response pacing rate profile, as examples. Other examples of changes in cardiac or patient-related conditions that can be detected to cause a change in pacing configuration are described herein, e.g., below in conjunction with FIG. 11.

[0121] The new pacing configuration selected at block 516 may be a pacing configuration tested during the pacing configuration assessment at block 510 that resulted in an improved cardiac-related condition (e.g.. an improvement in a metric of electrical synchrony or a metric of mechanical synchrony or hemodynamic function determined from signals sensed by sensing module 86). In other examples, the new pacing configuration may be the LOT-CRT pacing configuration. In other examples, the new pacing configuration may be CSP-only if the current pacing configuration is LV-only pacing or vice versa.

[0122] In some examples, the cunent pacing configuration may be assessed at block 510 without necessarily testing a different pacing configuration. A decline in a cardiac or patient-related condition detected at block 514 may warrant a change in pacing configuration at block 516, but the new pacing configuration may not have been tested or assessed during the pacing configuration assessment performed at block 510. As such, in some instances, at the time that the new pacing configuration is selected, it is not necessarily yet known to be more optimal than the current pacing configuration. A subsequent pacing configuration assessment may provide that determination.

[0123] If no change (e.g., no worsening or decline) in a cardiac-related or patient-related condition is detected from the assessment at block 514, control module 81 may determine if a change in a device-related condition is detected at block 518, based on the assessment performed at block 510, that may warrant a change in pacing configuration and / or a change in the trigger conditions for delivering LOT-CRT. A device-related condition may be predicted EOL of power source 90, e.g., reaching a threshold number of days predicted until elective device replacement or EOL at the current pacing configuration, or determining that a battery voltage measurement has decreased to or below a threshold voltage.

[0124] A device-related condition may be a change in lead / electrode impedance that may indicate shifting or dislodgement or a lead fracture or other lead issue. A device-related condition may be an increase in pacing pulse output (e.g., pulse voltage amplitude or pulse width), e.g., due to an increased pacing capture threshold. Control module 81 may be configured to performAttorney Docket: A0013968W001capture tests and, when loss of capture is detected, perform a capture threshold test to automatically adjust the pacing pulse output delivered to a ventricular pacing site to promote consistent pacing capture at that site. If the capture threshold for a CSP site or LV myocardial pacing site increases, the energy drain on power source 90 required for pacing at that pacing site may result in an undesirable shortening of the predicted time to EOL and may warrant a pacing configuration change.

[0125] A device-related condition may be a loss of conduction system capture (e.g., deep septal capture or myocardial only capture without capture of at least a portion of the conduction system at the CSP site). Control module 81 may be configured to analyze a sensed EGM signal, e.g., the pacing-evoked QRS waveform sensed following a CSP pulse, to discriminate between a QRS waveform that includes evidence of CSP capture and a QRS waveform that is evidence of loss of CSP capture, e g., septal myocardial or deep septal capture. A change in CSP capture type may be detected based on a change in the QRS morphology7during CSP-only pacing.

[0126] A device-related condition may be detection of oversensing, which may be due to noncardiac noise, a lead fracture, or shifting or dislodgement (e.g., retraction) of a ventricular pacing lead positioned at a CSP site or the LV myocardial pacing site. In some cases, a device-related condition may be the detection of extraneous tissue stimulation, e.g., phrenic nerve stimulation that may occur during pacing of the LV along the LV lateral free wall during LV-only pacing or LOT-CRT pacing. Phrenic nerve stimulation may be detected by control module 81 by analyzing an acoustical signal sensed by an acoustical sensor, e.g., a heart sound sensor, included in sensing module 81. Phrenic nerve stimulation may be detected by detecting a respiration sound, e g., a hiccup-like sound, that follows a delivered pacing pulse. For example, the LV lead 20 may be positioned such that electrodes along the lateral free wall of the LV may be in proximity to the phrenic nerve and cause phrenic nerve stimulation when an LV myocardial pacing pulse is delivered. In other examples, extraneous stimulation may be detected from an accelerometer signal or other motion sensor signal received from sensing module 81. Example methods for detecting extraneous stimulation that may be implemented in conjunction with the techniques disclosed herein are generally disclosed in U.S. Patent No. 8,538.523 (fding date September 14, 2012, Sommer, et al.) and in U.S. Patent No. 8,876,727 (fding date May 17, 2012, Zhang, et al.), the entire content of both of which is incorporated herein.

[0127] If no device-related condition is detected at block 518, the control module 81 may keep the current pacing configuration and return to block 506 to monitor for LOT-CRT trigger conditions. It is to be understood that if the current pacing configuration is LOT-CRT (based on a previous pacing configuration assessment), control module 81 may disable monitoring for LOT-CRT trigger conditions until a different pacing configuration is selected or programmed.Attorney Docket: A0013968W001

[0128] If a device-related condition is detected at block 518, control module 81 may adjust the LOT-CRT trigger conditions at block 520 in some examples. For example, if the power source is reaching EOL, is at or near an elective replacement time or the battery voltage has reached or fallen below a threshold level, control module 81 may disable some or all LOT-CRT trigger conditions to conserve the remaining life of power source 90. If LOT-CRT is triggered for delivery for a specified time interval or specified number of daily time periods, the specified time interval and / or number of time periods may be reduced to conserve power source 90. If phrenic nerve stimulation is detected, the LOT-CRT trigger conditions may be disabled at block 520 to avoid deli very of LV myocardial pacing that causes phrenic nerve capture. If loss of conduction system capture (e.g., loss of selective or non-selective capture resulting in myocardial only capture without capture of the conduction system) is detected, the LOT-CRT trigger conditions may or may not be adjusted at block 520. In some examples, LOT-CRT trigger conditions may be disabled if capture of the conduction system cannot be confirmed. However, septal pacing in combination with LV myocardial pacing along the lateral free wall using the LV lead may be delivered as a LOT-CRT pacing configuration, which may still promote improved electrical and / or mechanical synchrony compared to septal pacing alone or LV-only pacing.

[0129] If a relatively sudden lead impedance change, capture threshold change, noisy EGM signal and / or oversensing are detected indicating lead dislodgment or shifting, LOT-CRT may be disabled depending on the lead and / or capture threshold change location.

[0130] In some examples, the available pacing configuration selections may be adjusted by control module 81 at block 522 in response to detecting a change in a device-related condition. For instance, the LOT-CRT pacing configuration may be eliminated as an available pacing configuration at block 522 if the power source is reaching EOL. If phrenic nerv e stimulation is detected, the LOT-CRT and LV-only pacing configurations may be eliminated to avoid phrenic nerve stimulation. If conduction system capture is lost or the conduction system capture threshold is very high (e.g., within a safety margin of the maximum available pacing pulse output), the CSP-only pacing configuration may be eliminated. If a lead issue is detected (e.g., change in lead impedance or noise oversensing indicative of a lead fracture), the pacing site (e.g., the LV myocardial pacing site or the CSP site) associated with the lead issue may be eliminated from the available pacing configurations (which may leave only one pacing configuration, e.g., LV-only configuration or CSP-only configuration) in some instances.

[0131] At block 524, control module 81 may select a new pacing configuration in response to detecting the change in a device-related condition to mitigate the particular device-related condition detected. In some instances, only one pacing configuration may remain available for selection at block 524 (e.g., due to lead dislodgment or fracture, phrenic nerve stimulation, etc.).Attorney Docket: A0013968W001In other instances, the pacing configuration having the lowest capture threshold may be selected at block 524 if the power source longevity is reaching an elective replacement time or EOL. After selecting the new pacing configuration (or keeping the current pacing configuration depending on the device related condition detected at block 518), control module 81 may return to block 506 to monitor for LOT-CRT trigger conditions, which may be adjusted at block 520, if the LOT-CRT pacing configuration has not been eliminated due to a device-related condition. In some cases, if only one pacing configuration remains, e.g., due to a lead-related condition at either the CSP site or the LV myocardial pacing site or due to phrenic nerve stimulation during LV myocardial pacing, control module 81 may optionally disable the pacing configuration assessments. Control module 81 may generate a notification that can be transmitted by telemetry module 88 to programmer 24 to notify the clinician that the pacing configuration is now a fixed pacing configuration that is no longer being automatically adjusted, though the pacing cathode and anode electrodes, pacing pulse output, AV pacing delays, and / or VV pacing delays for the given pacing configuration may continue to be automatically adjusted as needed to optimize the pacing therapy delivery at the pacing site(s) of the fixed pacing configuration.

[0132] FIG. 11 is a flow chart 600 of methods for performing a pacing configuration assessment by an IMD or IMD system according to some examples. At block 602, control module 81 may determine one or more lead and / or device-related measurements for use in detecting a device-related condition, such as any of the examples described above. For example, control module 81 may obtain lead / electrode impedance measurements by controlling a pulse generator of therapy delivery module 84 to deliver a drive signal to measure the impedances between two electrodes carried by a given lead connected to IMD 16, e.g., lead 18, lead 20 and lead 22 (or between electrodes carried by the IMD housing in the case of IMD 114). Control module 81 may determine pacing capture thresholds (e.g.. the lowest pacing pulse output that “captures” at the pacing site, causing a pacing-evoked depolarization at the pacing site) at block 602 for the pacing sites of the test pacing configuration. Control module 81 may determine if evidence of noise is present in a sensed signal, e.g., by detecting noise pulses and / or frequent oversensing, that may be an indication of a lead issue, e.g.. poor connection to IMD 16, lead conductor fracture, etc. Control module 81 may measure the battery voltage and determine a battery EOL estimate. Control module 81 may determine the battery EOL estimate based on expected pacing frequency and pacing output (e.g., pulse amplitude and width) according to the current pacing output configuration in effect prior to starting the pacing configuration assessment and / or according to each test pacing configuration available in some examples.

[0133] At block 604, control module 81 may determine if a device-related condition is detected that warrants a change in pacing configuration. Any of the device-related conditions describedAttorney Docket: A0013968W001above in conjunction with FIG. 10 may be detected. For example, if a lead impedance changes by more than a threshold amount from a previous lead impedance measurement, the lead may have shifted or become dislodged or another lead-related issue, e.g., fracture, poor connection, etc., may have arisen. Additionally or alternatively, control module 81 may detect a device-related condition at block 604 if a capture threshold at a ventricular pacing site has increased greater than a pulse output limit (which may be associated with excessive battery drain). Additionally or alternatively, control module 81 may detect a device-related condition in response to the measured battery voltage or if determined battery EOL estimate is less than a threshold number of days. In some examples, a device-related condition may be the detection of phrenic (or other extraneous) nerve stimulation.

[0134] If a device-related condition is detected at block 604, this condition alone may warrant a change in pacing configuration. Control module 81 may identify an optimal pacing configuration at block 620, which may be LV-only when a large lead impedance change, high capture threshold or loss of conduction system capture that is associated w ith the CSP lead (e.g., lead 18 in FIG. 6) is the detected device-related condition. In other instances, the optimal pacing configuration may be CSP-only when a device-related condition is detected for the LV lead (e.g., lead 20 in FIG. 6). If control module 81 detects a device-related condition at block 604 that is related to a specific lead, the lead and associated pacing site(s) may be eliminated from the available pacing configurations. If a detected device-related condition is related to the remaining battery voltage or EOL prediction, the optimal pacing configuration identified at block 620 may be a pacing site associated w ith a lowest capture threshold (and only one pacing site as opposed to multiple pacing sites). If phrenic nerve stimulation is detected, control module 81 may identify the optimal pacing configuration at block 620 as CSP-only pacing to eliminate pacing by a coronary sinus lead, e.g.. LV lead 20 in FIG. 6, that may be stimulating the phrenic nerve during LV myocardial pacing.

[0135] If a device-related condition is not detected at block 604, control module 81 may perform a patient-related assessment at block 606. The patient-related assessment may be performed to assess symptoms or relatively more systemic or holistic conditions of the patient (e.g., versus conditions that are more direct assessments of cardiac function as described below in conjunction with blocks 610 and 612). The patient-related assessment may include a comparative analysis of metrics that may indicate the overall well-being of the patient, e.g., as a general indication of the effectiveness of the pacing configuration that has been in effect prior to starting the pacing configuration assessment. The patient-related assessment may include a comparison of a subjective, semi-quantitative or quantitative report of patient symptom(s) reported by the patient (e.g., via programmer 24) to previously reported patient symptoms(s). Examples of patient-Attorney Docket: A0013968W001reported symptoms are listed above. In some instances, the patient-reported symptom(s) may include a general report of feeling well or poorly (which may be on a semi-quantitative scale, e.g., 1 to 5) and / or feeling better or worse since a previous report.

[0136] Additionally or alternatively, control module 81 may compare a recent physical activity profile or rate response pacing rate profile to a previous profile. The physical activity profile may be determined from patient physical activity metrics determined from a signal sensed by sensing module 86 (e.g., accelerometer or other motion sensor signals, impedance or other respiration signals, etc.). The rate response pacing rate profile may be determined from the sensor indicated pacing rates that control module 81 may determine from the patient physical activity' metrics. A patient-related metric determined at block 606 may be a daily percentage of time that the patient physical activity level is at or above an activities of daily living threshold, a daily percentage of time that the intrinsic, sinus atrial rate is above a threshold rate (excluding time in atrial fibrillation or atrial flutter), or a daily percentage of time that the pacing rate delivered by therapy delivery' module 84 is at a rate response pacing rate greater than the programmed lower rate, as examples. In some examples, control module 81 may receive input from a fitness or activity tracker that may be worn by the patient that provides information relating to patient activity, sleep time and / or quality7and / or other patient-related metrics.

[0137] In the example shown, control module 81 may not make the decision to change the pacing configuration based only on the patient-related assessment performed at block 606. Control module 81 may advance to block 608 to perform cardiac-related assessments to use in combination wi th the patient-related assessment for making a pacing configuration selection based on the assessment. In other examples, however, if the patient-related assessment indicates a worsening condition (e.g., worsening symptoms and / or decreased patient physical activity), control module 81 may advance to block 620 (instead of block 608 as shown in FIG. 11) to change the pacing configuration based only on the patient-related assessment. A different pacing configuration may be selected w ithout performing any further assessment of the pacing configurations at blocks 608, 610, 612 as further described below. For example, control module 81 may switch from CSP-only pacing to LV only pacing at block 622 or vice versa in response to a worsening patient-related condition. In other examples, control module 81 may switch to LOT-CRT in an attempt to improve the therapeutic benefit to the patient in response to a worsening patient-related condition. Any improvement may be assessed in a subsequent pacing configuration assessment.

[0138] In the example shown, control module 81 may perform cardiac-related assessments so that if a patient-related condition warranting a change in pacing configuration is detected (or not), a new pacing configuration selection made by control module 81 can be informed by the resultsAttorney Docket: A0013968W001of the cardiac-related assessments. At block 608, control module 81 may select a test pacing configuration and control therapy delivery module 84 to deliver cardiac pacing according to the test pacing configuration. In some examples, the first test pacing configuration may be the pacing configuration in effect at the time that the pacing configuration assessment is started. In other examples, the first test pacing configuration may be any available pacing configuration and in some cases, e.g., upon IMD implantation, pacing has not yet been delivered according to any of the pacing configuration selections. The pacing configuration assessment may be performed for the first time for selecting an initial pacing configuration.

[0139] In some examples, control module 81 may perform a cardiac electrical activity7assessment (block 610) and a cardiac mechanical activity assessment (block 612) for each available pacing configuration. For the sake of illustration, the pacing configuration assessment described here includes controlling therapy deliver}' module 84 to deliver ventricular pacing according to three pacing configurations including CSP-only (e.g., LBBAP using lead 18 as shown in FIG. 6 without delivering LV myocardial pacing using lead 20), LV-only pacing (e.g., using lead 20 as shown in FIG. 6 without delivering CSP), and LOT-CRT pacing using both lead 18 and lead 20 to deliver pacing pulses at both a CSP site and an LV myocardial pacing site, e.g., simultaneously or separated by an interventricular (VV) pacing interval or each at specified AV pacing delays, on each cardiac cycle. It is to be understood, however, that performing the pacing configuration assessment may include delivering pacing according to the current pacing configuration being used to deliver pacing therapy at the time of the assessment and may not necessarily require assessment of other pacing configurations during every assessment.

[0140] At block 610, control module 81 may perform the cardiac electrical activity7assessment. To assess the cardiac electrical activity7, control module 81 may determine one or more cardiac electrical activity metrics from signals sensed by sensing module 86 during pacing according to the test pacing configuration. The cardiac electrical activity metrics may include cardiac conduction times (e.g., AV conduction time and / or interventricular conduction time) and / or metrics representative of cardiac electrical synchrony.

[0141] In some examples, control module 81 may determine a cardiac electrical activity metric by determining a morphology match score between one or more post-pace QRS waveforms sensed during ventricular pacing according to the test pacing configuration and one or more QRS waveform morphology7templates. The QRS waveform morphology7template may be established for the current pacing configuration at the time that the current pacing configuration was first selected (e.g., at block 404 of FIG. 9 or block 504 of FIG. 10). Additionally or alternatively, a QRS waveform morphology template may be established during the intrinsic ventricular rhythmAttorney Docket: A0013968W001to enable detection of a change or difference from the intrinsic QRS waveform morphology during pacing according to the test pacing configuration.

[0142] Control module 81 may determine one or more morphology match scores associated with the test pacing configuration to detect a QRS waveform morphology change, which may indicate a worsening or deterioration in electrical synchrony compared to a previously established QRS waveform morphology template for the same pacing configuration or compared to the QRS morphology of a different pacing configuration. For example, if a morphology match score between currently sensed QRS waveforms and a QRS waveform morphology template previously established for the same pacing configuration is low or is decreased from a previous morphology match score, control module 81 may detect a change in the cardiac electrical synchrony that may warrant a change in pacing configuration. The test pacing configuration may be less effective in promoting electrical synchrony than at the time that the morphology template was first established. If a morphology7match score between currently sensed post-pace QRS waveforms and an intrinsic QRS morphology template is high or increased from a previous morphology match score, the test pacing configuration may be less effective than desired for improving electrical synchrony (assuming the intrinsic QRS morphology is associated with poor ventricular electrical synchrony). As such, in some examples, control module 81 may detect a change in a cardiac-related condition at block 616 based on morphology match scores.

[0143] A morphology match score may be determined by determining a correlation coefficient or determining a sum of errors between wavelet transform coefficients of the test pacing configuration post-pace QRS waveforms and the QRS waveform morphology template. For example, a wavelet transform of the post-pace QRS waveform(s) sensed follow ing pacing delivering using the test pacing configuration may be performed to determine wavelet coefficients. The absolute differences between the filtered and normalized wavelet coefficients of the 0 through ith coefficients stored for each of the post-pace waveform(s) and the template may be summed to obtain a “distance” betw een the post-pace waveform and the template. The ratio of the distance to the wavelet representation of the template area (e.g., summation of the filtered and normalized wavelet transform coefficients of the template) may be determined. This ratio may be w eighted and subtracted from 100 to determine the match score between the post-pace w aveform morphology and the QRS waveform morphology template. In some examples, a morphology7match score may be determined for one or more horizontally (time-based) shifted post-pace waveforms and / or one or more vertically (amplitude-based) shifted post-pace waveforms (to account for any baseline offset due to pacing pulse delivery) and / or for the non-shifted post-pace waveform. The maximum morphology match score may be determined from all determined morphology7match scores and stored as the morphology7match score for the test pacingAttorney Docket: A0013968W001configuration. The morphology match score may be stored in memory 82 for comparison to previous morphology match scores and / or for comparison to morphology match scores determined during other test pacing configurations.

[0144] As described above, an LVAT metric and / or other QRS waveform features may be determined and stored at the time that a QRS waveform morphology template is established for a selected pacing configuration. At block 610, control module 81 may determine an LVAT metric from a ventricular EGM signal sensed by sensing module 84 during the test pacing configuration. Other examples of cardiac electrical activity metrics that may be determined at block 602 for the cardiac electrical activity assessment may include interventricular conduction time, AV conduction time, QRS width, and / or QRS area, with no limitation intended. An interventricular conduction time may be determined as the time interval from a ventricular pacing pulse delivered at one ventricular pacing site, e g., by lead 18 or by LV lead 20, to the QRS maximum peak (or other fiducial point of the QRS waveform) sensed using an electrode on another lead positioned at a different ventricular pacing site, e g., LV lead 20 or lead 18. AV conduction time may be determined between a sensed P-wave or delivered atrial pacing pulse and a sensed R-wave during the intrinsic ventricular rhythm to determine if AV block is present. The QRS width and / or QRS area or other features of the sensed ventricular EGM signal may be determined for comparison to features determined from a previously established QRS morphology template for the same pacing configuration and / or for comparison to the analogous feature determined during pacing delivered according to another test pacing configuration. It is recognized that a number of cardiac electrical activity metrics may be determined for assessing ventricular electrical synchrony and cardiac conduction times for use in detecting a cardiac electrical activity related change that may warrant a change in pacing configuration. For example, compared to a previous cardiac electrical activity assessment and / or compared to other test pacing configurations, a decrease in morphology match score, an increase in QRS width or area, an increase in LVAT, an increase in inter-ventricular conduction time, or an increase in AV conduction time may warrant a pacing configuration change.

[0145] At block 612, control module 81 may determine one or more cardiac mechanical activity metrics for assessing cardiac mechanical performance or determining the effectiveness of the test pacing configuration in promoting ventricular mechanical synchrony. A cardiac mechanical activity metric may be determined from a signal sensed by a cardiac mechanical activity7sensor of sensing module 86 during delivery of the test pacing configuration and, at least in some examples, during an intrinsic ventricular rhythm. Examples of cardiac mechanical activity metrics that may be determined by control module 81 include heart sound time intervals and / or heart sound amplitude (e.g., SI amplitude, S1-S2 heart sound intervals, the time interval from aAttorney Docket: A0013968W001delivered pacing pulse to an SI or S2 heart sound, and / or S3 heart sound amplitude as a metric of valve regurgitation), bio-impedance measurements of cardiac or thoracic impedance (e.g., impedance signal between an electrode carried by lead 18 and an electrode earned by lead 20 or the IMD housing electrode 58), pressure signal amplitude and / or rate of change (e.g., peak dP / dt), oxygen saturation measurements, or other indicators of ventricular mechanical synchrony or the hemodynamic performance of the heart. A cardiac impedance signal may be correlated to cardiac volume and can be a surrogate in estimating stroke volume, e.g., by determining peak-to-peak amplitude different in a cardiac impedance signal, and / or determining a surrogate of end-diastolic volume and / or end-systolic volume. A bio-impedance measurement may be an indication of fluid status of the patient, e.g., for tracking lung wetness or edema associated with HF and an indicator of worsening hemodynamic performance of the heart.

[0146] When a cardiac mechanical activity metric indicates a decrease in ventricular mechanical synchrony or worsening cardiac mechanical or hemodynamic performance, control module 81 may detect a change in a cardiac-related condition at block 616 that warrants a change in pacing configuration. A change in a cardiac mechanical activity metric that may be detected as a change in a cardiac-related condition by control module 81 may be, with no limitation intended, an increase in the S1-S2 heart sound intervals, an increase in S3 heart sound amplitude, decreased peak-to-peak cardiac impedance (suggesting decreased stroke volume), decreased bio-impedance (corresponding to greater fluid volume in the heart or chest), decreased peak dP / dt. or decreased oxygen saturation.

[0147] At block 614, control module 81 may determine if another test pacing configuration remains to be tested during the assessment. If so, control module 81 may return to block 608 and repeat the process of determining one or more cardiac electrical activity metrics at block 610 and / or determining one or more cardiac mechanical activity metrics at block 612 from signals sensed by sensing module 86 during the next test pacing configuration.

[0148] The patient-related assessment performed at block 606 may not be repeated for different test pacing configurations. At block 606, control module 81 may analyze patient-related conditions that reflect a relatively chronic response to the delivery of the currently selected pacing configuration, e.g., since at least the previous pacing configuration assessment. However, while patient-related assessment is shown at block 606 prior to applying different test pacing configurations, in other examples, control module 81 may receive patient-entered input via programmer 24 during different pacing configurations tested during the assessment. The patient may be prompted to report symptoms or better / worse subjective or semi-quantitative feeling of wellbeing during each test pacing configuration. Such patient reporting may reflect the acuteAttorney Docket: A0013968W001response to a pacing configuration change and may differentiate between pacing configurations that result in a clear change in symptoms for the patient.

[0149] After all test pacing configurations have been assessed ('‘no’’ branch of block 614), control module 81 may determine if a change in a cardiac-related (e.g., cardiac electrical activity or cardiac mechanical activity) or patient-related condition is detected at block 616. The change may be detected for the pacing configuration that was in effect at the time the assessment was started and may indicate a worsening of ventricular electrical synchrony or a cardiac conduction time, a worsening of ventricular mechanical synchrony or hemodynamic performance, or a worsening of patient symptoms or decrease in patient physical activity. If no change is detected, control module 81 may keep the current pacing configuration (in effect prior to starting the assessment) the same at block 618.

[0150] If a change in a cardiac-related or patient-related condition is detected at block 616, indicating a worsening condition during pacing according to the currently selected pacing configuration, control module 81 may identify an optimal pacing configuration at block 620. The optimal pacing configuration may be a pacing configuration that is associated with a cardiac electrical activity metric that indicates the greatest improvement in electrical synchrony (e.g., compared to the intrinsic ventricular rhythm and / or compared to other pacing configurations) and / or greatest improvement in mechanical synchrony (e.g., compared to intrinsic ventricular rhythm and / or other pacing configurations). For example, a clearly optimal pacing configuration may be identified based on the shortest LVAT, narrowest QRS width, smallest QRS area (which may be normalized by peak amplitude), shortest inter-ventricular conduction time, shortest S1-S2 interval, lowest S3 amplitude, highest SI amplitude, highest peak-to-peak cardiac impedance, or highest maximum dP / dt as non-limiting examples.

[0151] In some examples, the optimal pacing configuration may be a pacing configuration that results in substantially equivalent cardiac electrical activity metrics and / or cardiac mechanical activity7metrics compared to the other pacing configurations but has a lower capture threshold or total energy demand than the other pacing configurations. At block 622, control module 81 may¬ select the optimal pacing configuration that is used to control therapy delivery circuit 84 to deliver ventricular pacing, e.g., until the next pacing configuration is performed.

[0152] Further disclosed herein is the subject matter of the following examples:

[0153] Example 1. A medical device system including sensing circuitry' configured to sense one or more sensor signals including at least one cardiac signal and therapy delivery circuitry- configured to deliver cardiac pacing according to a pacing configuration that is selected by control circuitry of the medical device. The pacing configuration may be selected from among at least a first pacing configuration and a second pacing configuration wherein the therapy delivery'Attorney Docket: A0013968W001circuitry is configured to deliver first ventricular pacing pulses when the first pacing configuration is selected by delivering the first ventricular pacing pulses only to one or more left ventricular myocardial pacing sites and deliver second ventricular pacing pulses when the second pacing configuration is selected by delivering the second ventricular pacing pulses to at least a first conduction system pacing site. The control circuitry' may be configured to perform one or more pacing configuration assessments by selecting a first test configuration as the first pacing configuration and analyzing the at least one cardiac signal sensed during delivery' of the first ventricular pacing pulses according to the first pacing configuration. The control circuitry is configured to select the pacing configuration from among at least the first pacing configuration and the second pacing configuration based on the one or more pacing configuration assessments.

[0154] Example 2. The medical device system of example 1 wherein the control circuitry is further configured to select the second pacing configuration based on at least one of the one or more pacing configuration assessments, and the therapy delivery circuitry' is further configured to deliver the second ventricular pacing pulses according to the second pacing configuration by delivering the second ventricular pacing pulses to at least a left bundle branch area pacing site.

[0155] Example 3. The medical device system of example 1 wherein the control circuitry is further configured to select the second pacing configuration based on at least one of the one or more pacing configuration assessments, and the therapy delivery' circuitry' is further configured to deliver the second ventricular pacing pulses according to the second pacing configuration by delivering the second ventricular pacmg pulses to only one or more conductron system pacing sites comprising at least the first conduction system pacing site.

[0156] Example 4. The medical device system of any one of examples 1 — 2 wherein the control circuitry is further configured select the second pacing configuration based on the at least one of the one or more pacing configuration assessments, and the therapy delivery circuitry is further configured to deliver the second ventricular pacing pulses according to the second pacing configuration by delivering the second ventricular pacing pulses to at least the first conduction system pacing site and at least a first left ventricular myocardial pacing site of the one or more left ventricular myocardial pacing sites.

[0157] Example 5. The medical device system of any one of examples 1 — 3 wherein the control circuitry is further configured to select the pacing configuration from among the first pacing configuration, the second pacing configuration and a third pacing configuration and select the third pacing configuration based on at least one of the one or more pacing configuration assessments. The therapy delivery circuitry is further configured to deliver third ventricular pacing pulses according to the third pacing configuration by delivering the third ventricularAttorney Docket: A0013968W001pacing pulses to a combination of at least a first left ventricular myocardial pacing site of the one or more left ventricular myocardial pacing sites and the first conduction system pacing site.

[0158] Example 6. The medical device system of any one of examples 1 — 5 wherein the sensing circuitry includes at least one sensor for sensing the at least one cardiac signal by sensing at least one cardiac mechanical activity' signal. The control circuitry' may be further configured to perform the one or more pacing configuration assessments by determining at least one cardiac mechanical activity metric from the at least one cardiac mechanical activity' signal.

[0159] Example 7. The medical device system of example 6 wherein the sensing circuitry' includes a heart sound sensor for sensing the at least one cardiac mechanical activity' signal by sensing a heart sound signal. The control circuitry is further configured to determine the at least one cardiac mechanical activity metric by determining at least one of a heart sound interval and a heart sound amplitude.

[0160] Example 8. The medical device system of any one of examples 6 — 7 wherein the sensing circuitry includes impedance sensing circuitry for sensing the at least one cardiac mechanical activity signal by sensing a bioimpedance signal. The control circuitry may be further configured to determine the at least one cardiac mechanical activity metric by determining a bioimpedance.

[0161] Example 9. The medical device system of any one of examples 6 — 8 wherein the sensing circuitry' includes a pressure sensor for sensing the at least one cardiac mechanical activity signal by sensing a pressure signal. The control circuitry is further configured to determine the at least one cardiac mechanical activity metric by determining a maximum rate of change of the pressure signal.

[0162] Example 10. The medical device system of any one of examples 1 — 9 wherein the sensing circuitry is configured to sense the at least one cardiac signal by sensing one or more of: a heart sound signal, a pressure signal, an impedance signal, a motion signal and an oxygen saturation signal.

[0163] Example 11. The medical device system of any one of examples 1 — 10 wherein the sensing circuitry is further configured to sense the at least one cardiac signal by sensing at least one cardiac electrical signal. The control circuitry is further configured to perform the one or more pacing configuration assessments by determining at least one cardiac electrical activity metric from the at least one cardiac electrical signal.

[0164] Example 12. The medical device system of example 11 wherein the control circuitry' is further configured to determine the at least one cardiac electrical activity metric by determining at least one of: a QRS morphology match score, a left ventricular activation time, a QRS waveform feature, an interventricular conduction time and an atrioventricular conduction time.Attorney Docket: A0013968W001

[0165] Example 13. The medical device system of any one of examples 1 — 12 wherein the therapy delivery circuitry is further configured to be connected to at least a first pacing electrode for delivering the first ventricular pacing pulses according to the first pacing configuration and a second pacing electrode for delivering the second ventricular pacing pulses according to the second pacing configuration. The control circuitry may be further configured to perform the one or more pacing configuration assessments by measuring at least one of: a first impedance using the first pacing electrode and a second impedance using the second pacing electrode.

[0166] Example 14. The medical device system of any' one of examples 1 — 13 wherein the control circuitry7is further configured to perform the pacing configuration assessment by determining at least one of: a first pacing capture threshold for the first pacing configuration; and a second pacing capture threshold for the second pacing configuration.

[0167] Example 15. The medical device system of any one of examples 1 — 14 further including a power source for providing power to the therapy delivery' circuitry' for delivering the cardiac pacing. The control circuitry being further configured to perform the one or more pacing configuration assessments by measuring a voltage of the power source.

[0168] Example 16. The medical device system of any one of examples 1 — 15 wherein the sensing circuitry' further includes an activity7sensor for sensing a patient physical activity7signal. The control circuitry being further configured to perform the one or more pacing configuration assessments by determining an activity7profile from the patient physical activity signal.

[0169] Example 17. The medical device system of any one of examples 1 — 16 further including telemetry7circuitry configured to receive patient reported data transmitted by an external device. The control circuitry7being further configured to perform the one or more pacing configuration assessments by determining a change in the patient reported data.

[0170] Example 18. The medical device system of any one of examples 1 — 17 wherein the control circuitry is further configured to perform the one or more pacing configuration assessments by detecting extraneous nerve stimulation from a signal sensed by the sensing circuitry7and select the second pacing configuration in response to detecting the extraneous nerve stimulation.

[0171] Example 19. The medical device system of any one of examples 1 — 18 wherein the control circuitry is further configured to select the first pacing configuration based on at least one of the one or more pacing configuration assessments, detect a trigger condition and switch the pacing configuration selection from the first pacing configuration to a third pacing configuration in response to detecting the trigger condition. The therapy delivery circuitry being further configured to deliver third ventricular pacing pulses according to the third pacing configuration by delivering the third ventricular pacing pulses to a combination of at least a first left ventricularAttorney Docket: A0013968W001myocardial pacing site of the one or more left ventricular myocardial pacing sites and the first conduction system pacing site.

[0172] Example 20. The medical device system of example 19 wherein the control circuitry is further configured to determine that the trigger condition is terminated and switch the pacing configuration selection from the third pacing configuration back to the first pacing configuration in response to detecting the trigger condition termination.

[0173] Example 21. The medical device system of any one of examples 19 — 20 wherein the control circuitry is further configured to detect the trigger condition by detecting a specified time period.

[0174] Example 22. The medical device system of any one of examples 19 — 21 wherein the control circuitry is further configured to detect the trigger condition by detecting an atrial rate that is faster than a threshold rate from the at least one cardiac signal.

[0175] Example 23. The medical device system of any one of examples 19 — 21 wherein the control circuitry is further configured to detect the trigger condition by detecting atrioventricular conduction block from the at least one cardiac signal.

[0176] Example 24. The medical device system of any one of examples 19 — 23 wherein the sensing circuitry is further configured to sense a patient physical activity signal. The control circuitry7is further configured to detect a patient physical activity level that is greater than a threshold level based on the patient physical activity’ signal and detect the trigger condition by detecting the patient physical activity level.

[0177] Example 25. The medical device system of any one of examples 19 — 24 wherein the control circuitry’ is further configured to detect termination of a ventricular tachyarrhythmia from the at least one cardiac signal sensed by the sensing circuitry and detect the trigger condition by detecting the ventricular tachyarrhythmia termination.

[0178] Example 26. The medical device system of any one of examples 19 — 25 wherein the control circuitry is further configured to detect an increased fluid status from the one or more signals sensed by the sensing circuitry and detect the trigger condition by detecting the increased fluid status.

[0179] Example 27. The medical device system of any one of examples 19 — 26 wherein the control circuitry is further configured to determine one or more device-related conditions and disable detection of the trigger condition based on the one or more device-related conditions.

[0180] Example 28. The medical device system of any one of examples 1 — 27 wherein the control circuitry is further configured to perform the one or more pacing configuration assessments by selecting a second test configuration as the second pacing configuration andAttorney Docket: A0013968W001analyzing the at least one cardiac signal sensed during delivery of the second ventricular pacing pulses according to the second pacing configuration.

[0181] Example 29. The medical device system of any one of examples 1 — 28 wherein the control circuitry is further configured to perform a first pacing configuration assessment of the one or more pacing configuration assessments by determining at least one device-related condition, determining that the device-related condition is not a pacing configuration change condition and analyzing the at least one cardiac signal in response to determining that the devicerelated condition is not a pacing configuration change condition.

[0182] Example 30. The medical device system of any one of examples 1 — 29 wherein the control circuitry is further configured to perform a second pacing configuration assessment of the one or more pacing configuration assessments by determining at least one device-related condition and determining that the device-related condition is a pacing configuration change condition. The control circuitry may be further configured to select the pacing configuration based on the determined device-related condition in response to determining the device-related condition is a pacing configuration change condition.

[0183] Example 31. A method including sensing one or more signals including at least one cardiac signal and delivering cardiac pacing according to a pacing configuration, the pacing configuration being selected from among at least a first pacing configuration and a second pacing configuration wherein first ventricular pacing pulses are delivered according to the first pacing configuration by delivering the first ventricular pacing pulses only to one or more left ventncular myocardial pacing sites and second ventricular pacing pulses are delivered according to the second pacing configuration by delivering the second ventricular pacing pulses to at least a first conduction system pacing site. The method may further include performing one or more pacing configuration assessments by selecting a first test configuration as the first pacing configuration and analyzing the at least one cardiac signal sensed during delivery of the first ventricular pacing pulses according to the first pacing configuration. The method may include selecting the pacing configuration from among at least the first pacing configuration and the second pacing configuration based on the one or more pacing configuration assessments.

[0184] Example 32. The method of example 31 further including selecting the second pacing configuration based on at least one of the one or more pacing configuration assessments and delivering the second ventricular pacing pulses according to the second pacing configuration by delivering the second ventricular pacing pulses to at least a left bundle branch area pacing site.

[0185] Example 33. The method of any one of examples 31-32 further including selecting the second pacing configuration based on at least one of the one or more pacing configuration assessments and delivering the second ventricular pacing pulses according to the second pacingAttorney Docket: A0013968W001configuration by delivering the second ventricular pacing pulses to only one or more conduction system pacing sites comprising at least the first conduction system pacing site.

[0186] Example 34. The method of any one of examples 31 — 32 further including selecting the second pacing configuration based on at least one of the one or more pacing configuration assessments and delivering the second ventricular pacing pulses according to the second pacing configuration by delivering the second ventricular pacing pulses to at least the first conduction system pacing site and at least a first left ventricular myocardial pacing site of the one or more left ventricular myocardial pacing sites.

[0187] Example 35. The method of any one of examples 31 — 34 further including selecting the pacing configuration from among the first pacing configuration, the second pacing configuration and a third pacing configuration and selecting the third pacing configuration based on at least one of the one or more pacing configuration assessments. The method can further include delivering third ventricular pacing pulses according to the third pacing configuration by delivering the third ventricular pacing pulses to a combination of at least a first left ventricular myocardial pacing site of the one or more left ventricular myocardial pacing sites and the first conduction system pacing site.

[0188] Example 36. The method of any one of examples 31 — 35 further including sensing the at least one cardiac signal by sensing at least one cardiac mechanical activity signal and performing the one or more pacing configuration assessments by determining at least one cardiac mechanical activity metric from the at least one cardiac mechanical activity signal.

[0189] Example 37. The method of example 36 further including sensing the at least one cardiac mechanical activity signal by sensing a heart sound signal and determining the at least one cardiac mechanical activity metric by determining at least one of a heart sound interval and a heart sound amplitude.

[0190] Example 38. The method of any one of examples 36 — 37 further including sensing the at least one cardiac mechanical signal by sensing a bioimpedance signal and determining the at least one cardiac mechanical activity metric by determining a bioimpedance.

[0191] Example 39. The method of any one of examples 36 — 38 further including sensing the at least one cardiac mechanical signal by sensing a pressure signal and determining the at least one cardiac mechanical activity metric by determining a maximum rate of change of the pressure signal.

[0192] Example 40. The method of any one of examples 31 — 39 further including sensing the at least one cardiac signal by sensing one or more of: a heart sound signal, a pressure signal, an impedance signal, a motion signal and an oxygen saturation signal.Attorney Docket: A0013968W001

[0193] Example 41. The method of any one of examples 31 — 40 further including sensing the at least one cardiac signal by sensing at least one cardiac electrical signal and performing the one or more pacing configuration assessments by determining at least one cardiac electrical activity metric from the at least one cardiac electrical signal.

[0194] Example 42. The method of example 41 further including determining the at least one cardiac electrical activity metric by determining at least one of a QRS morphology’ match score, a left ventricular activation time, a QRS waveform feature, an interventricular conduction time; and an atrioventricular conduction time.

[0195] Example 43. The method of any one of examples 31 — 42 further including delivering the first ventricular pacing pulses according to the first pacing configuration via a first pacing electrode, delivering the second ventricular pacing pulses according to the second pacing configuration via a second pacing electrode and performing the one or more pacing configuration assessments by measuring at least one of a first impedance using the first pacing electrode and a second impedance using the second pacing electrode.

[0196] Example 44. The method of any one of examples 31 — 43 further including performing the one or more pacing configuration assessments by determining at least one of a first pacing capture threshold for the first pacing configuration and a second pacing capture threshold for the second pacing configuration.

[0197] Example 45. The method of any one of examples 31 — 44 further including performing the one or more pacing configuration assessments by measuring a voltage of a power source configured to provide power for generating the cardiac pacing.

[0198] Example 46. The method of any one of examples 31 — 45 further including sensing a patient physical activity signal and performing the one or more pacing configuration assessments by determining an activity profile from the patient physical activity signal.

[0199] Example 47. The method of any one of examples 31 — 46 further including receiving, by telemetry7circuitry’, patient reported data transmitted by an external device and performing the one or more pacing configuration assessments by determining a change in the patient reported data.

[0200] Example 48. The method of any one of examples 31 — 47 wherein performing the one or more pacing configuration assessments comprises detecting extraneous nerve stimulation from the one or more sensor signals. The method may further include selecting the second pacing configuration in response to detecting the extraneous nerve stimulation.

[0201] Example 49. The method of any one of examples 31 — 48 further including selecting the first pacing configuration based on at least one of the one or more pacing configuration assessments, detecting a trigger condition and switching the pacing configuration selection fromAttorney Docket: A0013968W001the first pacing configuration to a third pacing configuration in response to detecting the trigger condition. The method may further include delivering third ventricular pacing pulses according to the third pacing configuration by delivering the third ventricular pacing pulses to a combination of at least a first left ventricular myocardial pacing site of the one or more left ventricular myocardial pacing sites and the first conduction system pacing site.

[0202] Example 50. The method of example 49 further including determining that the trigger condition is terminated and switching the pacing configuration selection from the third pacing configuration back to the first pacing configuration in response to detecting the trigger condition termination.

[0203] Example 51. The method of any one of examples 49 — 50 further including detecting the trigger condition by detecting a specified time period.

[0204] Example 52. The method of any one of examples 49 — 52 further including detecting the trigger condition by detecting an atrial rate that is faster than a threshold rate from the at least one cardiac signal.

[0205] Example 53. The method of any one of examples 49 — 52 further including detecting the trigger condition by detecting atrioventricular conduction block from the at least one cardiac signal.

[0206] Example 54. The method of any one of examples 49 — 53 further including sensing the one or more signals by sensing a patient physical activity signal, detecting a patient physical activity level that is greater than a threshold level from the patient physical activity signal and detecting the trigger condition by detecting the patient physical activity level.

[0207] Example 55. The method of any one of examples 49 — 54 further including detecting termination of a ventricular tachyarrhythmia from the at least one cardiac signal and detecting the trigger condition by detecting the ventricular tachyarrhythmia termination.

[0208] Example 56. The method of any one of examples 49 — 55 further including detecting an increased fluid status from the one or more signals and detecting the trigger condition by detecting the increased fluid status.

[0209] Example 57. The method of any one of examples 49 — 56 further including determining one or more device-related conditions and disabling detection of the trigger condition based on the one or more device-related conditions.

[0210] Example 58. The medical device system of any one of examples 31 — 57 further including performing the one or more pacing configuration assessments by selecting a second test configuration as the second pacing configuration and analyzing the at least one cardiac signal sensed during delivery of the first pacing pulses according to the first test configuration andAttorney Docket: A0013968W001during delivery of the second ventricular pacing pulses according to the second test configuration.

[0211] Example 59. The method of any one of examples 31 — 58 wherein performing a first pacing configuration assessment of the one or more pacing configuration assessments includes determining at least one device-related condition, determining that the device-related condition is not a pacing configuration change condition and analyzing the at least one cardiac signal in response to determining that the device-related condition is not a pacing configuration change condition.

[0212] Example 60. The method of any one of examples 31 — 59 further including performing a second pacing configuration assessment of the one or more pacing configuration assessments by determining a device-related condition, determining that the device-related condition is a pacing configuration change condition and selecting the pacing configuration based on the determined device-related condition in response to determining that the device-related condition is a pacing configuration change condition.

[0213] Example 61. Non-transitory computer readable media storing a set of instructions that, when executed by processing circuitry of a medical device system, cause the system to sense one or more sensor signals including at least one cardiac signal and deliver cardiac pacing according to a pacing configuration, the pacing configuration being selected from among at least a first pacing configuration and a second pacing configuration. The instructions may further cause the medical device system to deliver first ventricular pacing pulses according to the first pacing configuration by delivering the first ventricular pacing pulses only to one or more left ventricular myocardial pacing sites and deliver second ventricular pacing pulses according to the second pacing configuration by delivering the second ventricular pacing pulses to at least a first conduction system pacing site. The instructions may further cause the medical device system to perform one or more pacing configuration assessments by analyzing the at least one cardiac signal and select the pacing configuration from among at least the first pacing configuration and the second pacing configuration based on the one or more pacing configuration assessments.

[0214] It should be understood that various aspects disclosed herein may be combined in different combinations than the combinations specifically presented in the description and accompanying drawings. It should also be understood that, depending on the example, certain acts or events of any of the processes or methods described herein may be performed in a different sequence, may be added, merged, or left out altogether (e.g., all described acts or events may not be necessary to carry out the techniques). In addition, while certain aspects of this disclosure are described as being performed by a single module or unit for purposes of clarity, itAttorney Docket: A0013968W001should be understood that the techniques of this disclosure may be performed by a combination of units or modules associated with, for example, a medical device.

[0215] In one or more examples, the described methods, processes, and techniques, including those attributed to the IMD 16 and the programmer 24 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 code on a computer-readable medium and executed by a hardware-based processing unit. Computer-readable media may include computer-readable storage media, which corresponds to a tangible medium such as data storage media (e.g., RAM, ROM, EEPROM, flash memory7, or any other medium that can be used to store desired program code in the form of instructions or data structures and that can be accessed by a computer).

[0216] 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 circuitry. The terms “computing apparatus,'’ “controller” “module,” “processor,” or “processing circuitry” may generally7refer to any of the foregoing logic circuitry, alone or in combination with other logic circuitry, or any other equivalent circuitry. Also, the techniques could be fully implemented in one or more circuits or logic elements. Depiction of different features as modules or units is intended to highlight different functional aspects and does not necessarily imply that such modules or units must be realized by separate hardware or software components. Rather, functionality associated with one or more modules or units may be performed by separate hardware or software components or integrated within common or separate hardware or software components.

[0217] All references and publications cited herein are expressly incorporated herein by reference in their entirety for all purposes, except to the extent any aspect directly contradicts this disclosure.

[0218] Unless otherwise indicated, all numbers expressing feature sizes, amounts, and physical properties used in the specification and claims may be understood as being modified either by the term “exactly” or “about.” Accordingly, unless indicated to the contrary7, the numerical parameters set forth in the foregoing specification and attached claims are approximations that can vary depending upon the desired properties sought to be obtained by those skilled in the art utilizing the teachings disclosed herein or, for example, within ty pical ranges of experimental error.

[0219] As used herein, the term “configured to” may be used interchangeably with the terms “adapted to” or “structured to” unless the content of this disclosure clearly dictates otherwise.Attorney Docket: A0013968W001

[0220] The singular forms “a,” “an,"’ and ‘‘the” encompass embodiments having plural referents unless its context clearly dictates otherwise.

[0221] As used herein, “have,” “having,” “include,” “including,” “comprise,” “comprising” or the like 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,” and the like are subsumed in “comprising.” and the like.

[0222] Reference to “one embodiment,” “an embodiment,” “certain embodiments,” or “some embodiments,” etc., means that a particular feature, configuration, composition, or characteristic described in connection w ith the embodiment is included in at least one embodiment of the disclosure. Thus, the appearances of such phrases in various places throughout are not necessarily referring to the same embodiment of the disclosure. Furthermore, the particular features, configurations, compositions, or characteristics may be combined in any suitable manner in one or more embodiments.

[0223] The words “preferred” and “preferably” refer to embodiments of the disclosure that may afford certain benefits, under certain circumstances. However, other embodiments may also be preferred, under the same or other circumstances. Furthermore, the recitation of one or more preferred embodiments does not imply that other embodiments are not useful and is not intended to exclude other embodiments from the scope of the disclosure.

Claims

Attorney Docket: A0013968W001WHAT IS CLAIMED IS:

1. A medical device system comprising:sensing circuitry configured to sense one or more sensor signals comprising at least one cardiac signal;therapy delivery circuitry configured to deliver cardiac pacing according to a pacing configuration that is selected by control circuitry of the medical device, the pacing configuration being selected from among at least a first pacing configuration and a second pacing configuration, the therapy delivery circuitry configured to:deliver first ventricular pacing pulses when the first pacing configuration is selected by delivering the first ventricular pacing pulses only to one or more left ventricular myocardial pacing sites; anddeliver second ventricular pacing pulses when the second pacing configuration is selected by delivering the second ventricular pacing pulses to at least a first conduction system pacing site; andthe control circuitry' being configured to:perform one or more pacing configuration assessments by:selecting a first test configuration as the first pacing configuration; and analyzing the at least one cardiac signal sensed during delivery of the first ventricular pacing pulses according to the first pacing configuration; and select the pacing configuration from among at least the first pacing configuration and the second pacing configuration based on the one or more pacing configuration assessments.

2. The medical device system of claim 1 wherein:the control circuitry' is further configured to select the second pacing configuration based on at least one of the one or more pacing configuration assessments; andthe therapy delivery circuitry is further configured to deliver the second ventricular pacing pulses according to the second pacing configuration by delivering the second ventricular pacing pulses to only one or more conduction system pacing sites comprising at least the first conduction system pacing site.Attorney Docket: A0013968W0013. The medical device system of claim 1 wherein:the control circuitry is further configured select the second pacing configuration based on the at least one of the one or more pacing configuration assessments; andthe therapy delivery circuitry is further configured to deliver the second ventricular pacing pulses according to the second pacing configuration by delivering the second ventricular pacing pulses to at least the first conduction system pacing site and at least a first left ventricular myocardial pacing site of the one or more left ventricular myocardial pacing sites.

4. The medical device system of any one of claims 1 — 2 wherein:the control circuitry is further configured to:select the pacing configuration from among the first pacing configuration, the second pacing configuration and a third pacing configuration; andselect the third pacing configuration based on at least one of the one or more pacing configuration assessments; andthe therapy delivery circuitry is further configured to deliver third ventricular pacing pulses according to the third pacing configuration by delivering the third ventricular pacing pulses to a combination of at least a first left ventricular myocardial pacing site of the one or more left ventricular myocardial pacing sites and the first conduction system pacing site.

5. The medical device system of any one of claims 1 — 4 wherein:the sensing circuitry comprises at least one sensor for sensing at least one cardiac mechanical activity signal; andthe control circuitry' is further configured to perform the one or more pacing configuration assessments by determining at least one cardiac mechanical activity metric from the at least one cardiac mechanical activity signal.

6. The medical device system of any one of claims 1 — 5 wherein:the sensing circuitry is further configured to sense the at least one cardiac signal by sensing at least one cardiac electrical signal; andthe control circuitry is further configured to perform the one or more pacing configuration assessments by determining at least one cardiac electrical activity metric from the at least one cardiac electrical signal.Attorney Docket: A0013968W0017. The medical device system of any one of claims 1 — 6 wherein:the therapy delivery circuitry is configured to be connected to at least:a first pacing electrode for delivering the first ventricular pacing pulses according to the first pacing configuration; anda second pacing electrode for delivering the second ventricular pacing pulses according to the second pacing configuration;the control circuitry is further configured to perform the one or more pacing configuration assessments by measuring at least one of:a first impedance using the first pacing electrode;a second impedance using the second pacing electrode.a first pacing capture threshold for the first pacing configuration; and a second pacing capture threshold for the second pacing configuration.

8. The medical device system of any one of claims 1 — 7 further comprising a power source for providing power to the therapy delivery circuitry for delivering the cardiac pacing; and wherein the control circuitry is further configured to perform the one or more pacing configuration assessments by measuring a voltage of the power source.

9. The medical device system of any one of claims 1 — 8 wherein the sensing circuitry further comprises an activity sensor for sensing a patient physical activity signal; and wherein the control circuitry is further configured to perform the one or more pacing configuration assessments by determining an activity profile from the patient physical activity signal.

10. The medical device system of any one of claims 1 — 9 further comprising:telemetry circuitry configured to receive patient reported data transmitted by an external device; andwherein the control circuitry is further configured to perform the one or more pacing configuration assessments by determining a change in the patient reported data.Attorney Docket: A0013968W00111. The medical device system of any one of claims 1 — 10 wherein the control circuitry is further configured to:perform the one or more pacing configuration assessments by detecting extraneous nerve stimulation from a signal sensed by the sensing circuitry; andselect the second pacing configuration in response to detecting the extraneous nerve stimulation.

12. The medical device system of any one of claims 1 — 11 wherein:the control circuitry is further configured to:select the first pacing configuration based on at least one of the one or more pacing configuration assessments;detect a trigger condition; andswitch the pacing configuration selection from the first pacing configuration to a third pacing configuration in response to detecting the trigger condition; andthe therapy delivery circuitry is further configured to deliver third ventricular pacing pulses according to the third pacing configuration by delivering the third ventricular pacing pulses to a combination of at least a first left ventricular myocardial pacing site of the one or more left ventricular myocardial pacing sites and the first conduction system pacing site.

13. The medical device system of claim 12 wherein the control circuitry is further configured to detect the trigger condition by detecting a specified time period.

14. The medical device system of any one of claims 12 — 13 wherein the control circuitry' is further configured to detect the trigger condition from the one or more sensor signals by detecting at least one of:an atrial rate that is faster than a threshold rate;atrioventricular conduction block;a patient physical activity level that is greater than a threshold activity’ level; termination of a ventricular tachyarrhythmia;an increased fluid status from the one or more signals sensed by the sensing circuitry.Atorney Docket: A0013968W00115. A method comprising :sensing one or more signals including at least one cardiac signal;delivering cardiac pacing according to a pacing configuration, the pacing configuration being selected from among at least a first pacing configuration and a second pacing configuration wherein:first ventricular pacing pulses are delivered according to the first pacing configuration by delivering the first ventricular pacing pulses only to one or more left ventricular myocardial pacing sites; andsecond ventricular pacing pulses are delivered according to the second pacing configuration by delivering the second ventricular pacing pulses to at least a first conduction system pacing site;performing one or more pacing configuration assessments by selecting a first test configuration as the first pacing configuration and analyzing the at least one cardiac signal sensed during delivery of the first ventricular pacing pulses according to the first pacing configuration; andselecting the pacing configuration from among at least the first pacing configuration and the second pacing configuration based on the one or more pacing configuration assessments.

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