Conductive system pacing control

Abstract

An implantable medical device includes a first lead carrying a first set of electrodes and configured to be implanted in a ventricular septum of a heart to position at least one electrode of the first set of electrodes in a left bundle branch region proximate a left ventricular septum. The implantable medical lead also includes a second lead carrying a second set of electrodes and configured to be implanted in the coronary sinus of the heart. A sensing circuit of the implantable medical device is configured to sense depolarization from pacing pulses delivered by the set of electrodes. The processing circuit is configured to determine a conduction time of the pacing pulse. The processing circuit is configured to determine whether the left beambranch region pulse includes left beambranch pacing based on the first conduction time and the second conduction time.

Description

[0001] This application claims the benefit of U.S. Provisional Patent Application Serial No. 63 / 380,156, filed Oct. 19, 2022, the entire contents of which are incorporated herein by reference. Technical Field

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

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

[0004] Conduction system pacing (CSP) is a technique that uses the native conduction system of the heart to provide pacing depolarizations and the resulting contractions that better mimic the intrinsic depolarizations and contractions, which can improve the health and pumping efficiency of the heart. Exemplary types of conduction system pacing include His bundle pacing, left bundle branch pacing (LBBP), right bundle branch pacing (RBBP), and bilateral bundle branch pacing (BBBP). Exemplary locations for accessing the conduction system include the ventricular septum via the right ventricle and the atrioventricular septum via the right atrium, such as at the area of Koch's triangle. In some examples, CSP can provide cardiac resynchronization without the need to deliver cardiac pacing to the left side of the heart. Summary of the Invention

[0005] CSP (such as LBBP) is a physiological pacing mode that can be superior to conventional biventricular CRT in some aspects. For example, CSP can be more energy-efficient than conventional biventricular CRT because CSP can use a single ventricular lead and the heart's natural conduction system (His-Purkinje fibers) to deliver cardiac pacing to rapidly conduct action potentials along the ventricular septum, thereby rapidly spreading the depolarization wavefront through the remaining ventricular myocardium and generating a coordinated contraction of the ventricular muscle groups. In contrast, conventional or traditional CRT pacing therapy can be described as delivering pacing pulses into myocardial tissue that is not part of the cardiac conduction system of the patient's heart, such that, for example, the pacing pulses trigger electrical activation that propagates primarily from one myocardial cell to another (also known as "cell-to-cell"), as opposed to propagating within the cardiac conduction system prior to the myocardial tissue. Additionally, conventional CRT can rely on using two ventricular leads for pacing therapy. However, confirming successful LBB capture and more generally CSP during and after implantation can be challenging. Unsuccessful CSP can result in myocardial pacing. For example, unsuccessful LBB capture can result in local left ventricular septal pacing (LVSP) without directly capturing the left bundle branch (LBB).

[0006] Generally, the present disclosure relates to techniques for determining whether electrical stimulation has achieved CSP, or alternatively has resulted in less efficient myocardial pacing. In some examples, an implantable medical device includes: a connector block configured to be coupled to a plurality of leads, the plurality of leads including a first lead that carries a first set of electrodes and is configured to be implanted in the ventricular septum of the heart to position at least one of the first set of electrodes in the left bundle branch region near the left ventricular septum; and a second lead that carries a second set of electrodes and is configured to be implanted in the coronary sinus of the heart; and sensing circuitry configured to: sense a first depolarization generated by a first pacing pulse delivered by the first set of electrodes via the second set of electrodes; and sense a second depolarization generated by a second pacing pulse delivered by the second set of electrodes via the first set of electrodes; and processing circuitry configured to: determine a first conduction time of the first pacing pulse from the left ventricular septum to the coronary sinus based on the sensing of the first depolarization; determine a second conduction time of the second pacing pulse from the coronary sinus to the left ventricular septum based on the sensing of the second depolarization; and determine whether the first pacing pulse includes left bundle branch pacing based on the first conduction time and the second conduction time.

[0007] In some examples, a medical system includes: a plurality of leads, the plurality of leads including: a first lead that carries a first set of electrodes and is configured to be implanted in the interventricular septum of the heart to position at least one of the first set of electrodes in the left bundle branch region near the left ventricular septum; and a second lead that carries a second set of electrodes and is configured to be implanted in the coronary sinus of the heart; an implantable medical device coupled to the plurality of leads, the implantable medical device including: a connector block configured to be coupled to the plurality of leads; a sensing circuit configured to: sense, via the second set of electrodes, a first depolarization generated by a first pacing pulse delivered by the first set of electrodes; and sense, via the first set of electrodes, a second depolarization generated by a second pacing pulse delivered by the second set of electrodes; and a processing circuit configured to: determine a first conduction time of the first pacing pulse from the left ventricular septum to the coronary sinus based on the sensing of the first depolarization; determine a second conduction time of the second pacing pulse from the coronary sinus to the left ventricular septum based on the sensing of the second depolarization; and determine whether the first pacing pulse includes left bundle branch region pacing based on the first conduction time and the second conduction time; and an external device configured to: be communicatively coupled to the implantable medical device; and output an indication of whether the first pacing pulse includes left bundle branch pacing.

[0008] In some examples, a method includes: sensing, via a second set of electrodes of a second lead of an implantable medical device, a first depolarization generated by a first pacing pulse delivered by a first set of electrodes of a first lead of the implantable medical device, wherein the second set of electrodes is positioned in the coronary sinus, wherein the first set of electrodes is implanted in the interventricular septum of the heart, and wherein at least one of the first set of electrodes is located in the left bundle branch region near the left ventricular septum; and sensing, via the first set of electrodes, a second depolarization generated by a second pacing pulse delivered by the second set of electrodes; determining, by a processing circuit of the implantable medical device, a first conduction time of the first pacing pulse from the left ventricular septum to the coronary sinus based on the sensing of the first depolarization; determining, by the processing circuit, a second conduction time of the second pacing pulse from the coronary sinus to the left ventricular septum based on the sensing of the second depolarization; and determining, by the processing circuit, whether the first pacing pulse includes left bundle branch pacing based on the first conduction time and the second conduction time.

[0009] This summary is intended to provide an overview of the subject matter described in this disclosure. It is not intended to provide an exclusive or exhaustive interpretation of the devices and methods described in the following figures and description. Details of one or more aspects of the disclosure are set forth in the following figures and specification. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1A conceptual diagram illustrating an example of a medical device system including an implantable medical device and an external device coupled to a patient's heart.

[0011] Figure 2 A conceptual diagram illustrating a part of a medical device system coupled to a patient's heart Figure 1 .

[0012] Figure 3 An exemplary functional block diagram illustrating Figure 1 an exemplary configuration of an exemplary implantable medical device.

[0013] Figure 4 An exemplary functional block diagram illustrating an exemplary system including an external device such as a server, and one or more computing devices coupled to an implantable medical device and an external device via a network Figure 1 .

[0014] Figures 5A to 5B A timing diagram illustrating ventricular activation sensing.

[0015] Figure 6 A flowchart illustrating an exemplary technique for selecting between conduction system pacing and cardiac resynchronization pacing according to the techniques of the present disclosure. Detailed Description

[0016] Generally, the present disclosure describes exemplary techniques related to conduction system pacing (CSP). CSP is a technique in which one or more pacemaker devices use the native electrical conduction system of the heart to conduct electrical signals that cause myocardial depolarization, which ultimately causes synchronous contraction of the ventricles. In this way, CSP can provide benefits associated with cardiac resynchronization therapy (CRT). The system can provide different types of CSP, depending on which part of the native electrical conduction system of the heart is the target of electrical stimulation. Examples of CSP include left bundle branch pacing (LBBP), right bundle branch pacing (RBBP), bilateral bundle branch pacing (BBBP), His bundle pacing (HBP), etc.

[0017] As used herein, left bundle branch area pacing (LBBAP) refers to pacing near the LBB and can include left bundle branch pacing (LBBP) with LBB capture and left ventricular septal pacing (LVSP) without LBB capture. LBBP may be superior to LVSP because LBBP captures a part of the heart's natural conduction system, while LVSP does not capture a part of the heart's natural conduction system. As used herein, LBB refers to the left bundle branch located in the subendocardial region of the left ventricular septum. The ventricular septum (e.g., interventricular septum) can be divided into a right ventricular septum on the right side of the ventricular septum and a left ventricular septum on the left side of the ventricular septum.

[0018] Figure 1FIG. 0 is a conceptual diagram illustrating an example of a medical device system 2 coupled to a patient's heart 6, the medical device system including an implantable medical device 4 (“IMD 4”) and an external device 8. Figure 2 FIG. 2 is a conceptual diagram further illustrating a portion of the medical device system 2 coupled to the heart 6. The medical device system 2 is an example of a medical device system configured to implement the exemplary techniques described herein for determining whether a pacing pulse includes LBBP and for selecting between CSP and biventricular CRT pacing in accordance with the techniques of the present disclosure.

[0019] In some examples, the IMD 4 can be an implantable multi-channel cardiac pacemaker, an implantable cardioverter defibrillator (ICD), an implantable pulse generator (IPG), a leadless (e.g., intracardiac) pacemaker, an epicardial pacemaker, and / or an ICD, or other IMD configured to deliver CSP to the heart 6 or a combination of such IMDs. In some instances, the IMD 4 can be configured to sense electrical signals corresponding to depolarization and repolarization of the heart 6 via electrodes on one or more leads 12, 14, and 16 or the housing of the IMD 4, such as an electrogram (EGM). Additionally or alternatively, the IMD 4 can sense electrical signals corresponding to depolarization and repolarization of the heart 6 via extracorporeal electrodes (e.g., electrodes positioned external to the patient's vasculature) such as epicardial electrodes, outer surface electrodes, subcutaneous electrodes, etc. In any such instance, the configuration of the electrodes of the IMD 4 for sensing and pacing can be monopolar or bipolar. In some examples, the IMD 4 can determine a heart rate based on the electrical signals sensed via the electrodes to, for example, detect arrhythmias. The IMD 4 can also deliver therapy to the heart 6 in the form of electrical signals via electrodes positioned on one or more leads 12, 14, and 16 or the housing of the IMD 4. In the illustrated example, the IMD 4 is connected to the leads 12, 14, and 16 and is communicatively coupled to the external device 8.

[0020] The leads 12, 14, and 16 extend into the patient's heart 6 to sense the electrical activity of the heart 6 and deliver electrical stimulation to the heart 6. In Figure 1 the example shown, the first lead 12 extends through one or more veins (not shown), the vena cava 20, the right atrium 22 (“RA 22”), the right ventricle 24 (“RV 24”), and to the interventricular septum to sense cardiac signals and deliver CSP (e.g., LBBP). The first lead 12 can carry a first set of electrodes. The second lead 14 can carry a second set of electrodes. In examples where the IMD 4 includes a third lead 16, the third lead 16 can carry a third set of electrodes. As used herein, a set can refer to one or more elements. For example, a set of electrodes can refer to one or more electrodes.

[0021] The first lead 12 may be configured to be implanted in the RV of the heart 6 to position at least one electrode of the first set of electrodes in the left bundle branch region near the left ventricular septum. In Figure 1 an example, the distal end of the first lead 12 is positioned via the RV 24 at the interventricular septum between the RV 24 and the left ventricle 28 ("LV 28") for delivery of CSP. The electrodes 34 of the first lead 12 may extend into the interventricular septum to facilitate capture of the conduction system with electrical stimulation delivered via the electrodes 34. In other examples, the electrodes for delivery of CSP may be positioned in other locations (such as via the atrioventricular septum of the Koch triangle). In some examples, the system 2 may include one or more leadless pacing devices configured to deliver CSP, for example, instead of one or more of the leads 12, 14, and 16.

[0022] The second lead 14 may be configured to be implanted in the coronary sinus (CS) of the heart 6 to position the second set of electrodes in the CS. In Figure 1 an example, the second lead 14 extends through one or more veins, the vena cava 20, the RA 22 and into the coronary sinus 26 (illustrated in dashed lines) to reach a region adjacent to the free wall of the LV 28 of the heart 6 to sense left ventricular cardiac signals and deliver therapeutic signals to the LV 28. In some examples, the second lead 14 may also be referred to as a sinus CS lead. As Figure 1 further shown in an example, the third lead 16 extends through one or more veins and the vena cava 20 and is positioned such that the distal end of the third lead 16 is located near the RA 22 and the vena cava 20 to sense right atrial cardiac signals and deliver therapeutic signals to the RA 22.

[0023] In the illustrated example, the first lead 12 includes bipolar electrodes 32 and 34 that may be positioned adjacent to the distal end of the first lead 12. The third lead 16 includes bipolar electrodes 36 and 37 that may be positioned adjacent to the distal end of the third lead 16. The second lead 14 may be a multipolar LV lead and may include electrodes 42, 44, 46, and 48. In some examples, the electrodes 42, 44, 46, and 48 may be positioned adjacent to the distal end of the second lead 14, as Figure 1 and Figure 2 illustrated.

[0024] The electrodes 34 and / or 36 may be fixed or extendable helical tip electrodes and may be mounted on respective insulated electrode heads. The electrodes 32 and 37 may be annular electrodes that respectively form the outer surfaces of the leads 12 and 16. An example of such a lead may be SELECTSECURE TMLead 3830. Additionally, although electrodes 32 and 37 are typically shown within the chamber volumes of the RV and RA, in other examples, electrodes 32 and 37 can be positioned within a portion of the heart tissue. For example, electrode 32 can be positioned within the ventricular septum near the right ventricular septum and the right bundle branch. Electrode 32 can be used in such examples to facilitate capture of the conduction system (e.g., right bundle branch fibers).

[0025] In some examples, electrodes 32 through 48 of leads 12, 14, and 16 can be electrically coupled to corresponding conductors within the lead bodies of the respective leads among leads 12, 14, and 16, and thereby coupled to circuitry within IMD 4. In some instances, leads 12, 14, and 16 respectively include series connectors 50, 52, and 54. IMD 4 can also include a connector block 58 and a hermetically sealed housing 60. Series connectors 50, 52, and 54 can be configured to fit into corresponding bipolar holes of connector block 58, which can be coupled to electrically insulated conductors within leads 12, 14, and 16, thereby connecting electrodes 32 through 48 to IMD 4. In this manner, connector block 58 can be configured to couple to leads 12, 14, and 16.

[0026] In some instances, one or more outward-facing portions of housing 60 can be non-insulated, and thus can enable housing 60 to function as a housing electrode. In some instances, substantially all of housing 60 can be non-insulated such that substantially all of housing 60 defines a housing electrode. In some other examples, housing 60 can define one or more additional housing electrodes (not shown) that can be defined by corresponding divisions between insulated and non-insulated portions of housing 60. In some examples, IMD 4 can be configured to perform bipolar sensing of electrical signals corresponding to electrocardiograms of heart 6 via any bipolar combination of electrodes 32 through 48. In other examples, IMD 4 can be configured to perform bipolar sensing of electrical signals corresponding to electrocardiograms of heart 6 via any one of electrodes 32 through 48 in combination with housing electrode 60.

[0027] In an example, instead of or in addition to Figure 1 the illustrated electrodes of leads 12, 14, and 16, medical device system 2 can include extracardiac electrodes other than, such as subcutaneous electrodes, subxiphoid electrodes, epicardial electrodes, and / or patch electrodes, etc. In some other examples, a medical device configured to deliver cardiac therapy may not have to be implanted within a patient. In some such examples, the medical device can deliver pacing therapy and other therapies to heart 6 via percutaneous leads that extend through the patient's skin to one or more locations within or outside of heart 6.

[0028] In some other examples, the medical device system 2 can include any suitable number of leads coupled to the IMD 4 and extending to any suitable location within or near the heart 6. For example, the medical device system 2 can include a dual-chamber IMD instead of a triple-chamber IMD (such as the IMD 4). In one example of a dual-chamber configuration, the IMD 4 is connected to leads 12 and 16.

[0029] Instead of or in addition to the IMD 4, the medical device system 2 can include one or more leadless (e.g., intracardiac) pacing devices (LPDs). In such instances, the one or more LPDs can include therapy delivery circuitry and processing circuitry within a housing configured for implantation on or within one of the chambers of the heart 6. In such systems, one or more pacing devices including one or more LPDs and / or IMDs coupled to one or more leads can communicate to coordinate sensing and pacing in the respective chambers of the heart 6 to provide CSP and CRT in accordance with the techniques described herein.

[0030] The external device 8 can be a computing device (e.g., for a home, outpatient, clinic, or hospital environment) to communicate with the ICM 10 via wireless telemetry. The external device 8 can include or be coupled to a remote patient monitoring system, such as available from (Medtronic plc, of Dublin, Ireland). As an example, the external device 8 can be a programmer, an external monitor, or a consumer device (e.g., a tablet or a smart phone). In some instances, the external device 8 can receive data, alerts, patient physiological information, or other information from the IMD 4.

[0031] In some instances, the external device 8 can be used to program commands or operating parameters into the IMD 4 to control its operation (e.g., when configured as a programmer for the IMD 4). The external device 8 can be used to interrogate the IMD 4 to retrieve data, including device operation data and physiological data accumulated in the IMD memory. The interrogation can be automatic, such as according to a schedule or in response to a remote or local user command. Programmers, external monitors, and consumer devices are examples of external devices 18 that can be used to interrogate the IMD 4. Examples of communication technologies used by the IMD 4 and the external device 8 include radio frequency (RF) telemetry, which can be an RF link established via Bluetooth, WiFi, or medical implant communication service (MICS). In some instances, the external device 8 includes processing circuitry. The processing circuitry of the external device 8 can be configured to perform any of the techniques described regarding the processing circuitry of the medical device system 2, as further described herein.

[0032] Figure 3 is a functional block diagram illustrating an exemplary configuration of the IMD 4. AsFigure 3 As shown, the IMD 4 includes a processing circuit 102, a sensing circuit 104, a therapy delivery circuit 106, a sensor 108, a communication circuit 110, and a memory 112. Additionally, the IMD 4 is coupled to one or more electrodes 116, which can be any one or more of the previously described electrodes of the medical system 2, and one or more of these electrodes can be disposed on the housing 60 of the IMD 4 or carried by one or more leads 12, 14, and / or 16 connected to the IMD 4. In some examples, the memory 112 includes computer-readable instructions that, when executed by the processing circuit 102, cause the IMD 4 and the processing circuit 102 to perform the various functions attributed herein to the IMD 4 and the processing circuit 102. The memory 112 can include any volatile memory, non-volatile memory, magnetic memory, optical memory, or dielectric memory, such as random access memory (RAM), read-only memory (ROM), non-volatile RAM (NVRAM), electrically erasable programmable ROM (EEPROM), flash memory, or any other digital medium.

[0033] The processing circuit 102 can include fixed-function circuitry and / or programmable processing circuitry. The processing circuit 102 can 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), or equivalent discrete or analog logic circuitry. In some examples, the processing circuit 102 can include multiple components (such as any combination of one or more microprocessors, one or more controllers, one or more DSPs, one or more ASICs, or one or more FPGAs) and other discrete or integrated logic circuitry. The functions attributed herein to the processing circuit 102 can be embodied as software, firmware, hardware, or any combination thereof.

[0034] ​The sensing circuit 104 and the therapy delivery circuit 106 may be selectively coupled to the electrode 116, for example, via a switching circuit (not shown) controlled by the processing circuit 102. The switching circuit may include one or more transistors or other circuitry for selectively coupling the electrode 116 to the circuitry of the IMD 4. The sensing circuit 104 may monitor signals from the electrode 116, such as intracardiac electrograms (EGMs), to monitor the electrical activity of the heart (e.g., detecting depolarizations for heart rate determination and / or sensing LV activation to determine if electrical stimulation results in CSP). The sensing circuit 104 may also monitor signals from one or more other sensors 108, for example, to determine the patient's activity level or activity. In some examples, the sensors 108 may be one or more accelerometers (e.g., one or more triaxial accelerometers), one or more temperature sensors, or one or more other sensors configured to sense the patient's body parameters. Signals generated by such sensors may indicate the patient's body parameters, such as overall body movement, posture, exertion, temperature, activity level, or other body parameters. The sensing circuit 104 may monitor signals from the electrode 116 and the sensors 108. In some instances, the sensing circuit 104 may include one or more filters and amplifiers for filtering and amplifying signals received from one or more of the electrodes 116 and / or one or more of the sensors 108. The sensing circuit 104 may also include rectifying circuitry, sample-and-hold circuitry, one or more comparators, and / or analog-to-digital conversion circuitry. The functions provided by such circuitry may be applied to signals in either the analog or digital domain.

[0035] The therapy delivery circuit 106 may include circuitry for generating signals (such as one or more capacitors, charge pumps, and / or current sources) and circuitry for selectively coupling the signals to the electrode 116 (e.g., transistors or other switching circuitry). The therapy delivery circuit 106 may be configured to deliver pacing pulses or other therapeutic stimulation signals. As will be described in more detail below, the processing circuit 102 may be configured to control the therapy delivery circuit 106 to deliver CSP and / or CRT via selected combinations of the electrodes 116.

[0036] The communication circuit 110 may include any suitable hardware, firmware, software, or any combination thereof for communicating with another device (such as an external device 8) or another IMD or sensor. For example, the communication circuit 110 may include a voltage regulator, a current generator, an oscillator or circuitry for generating signals, resistors, capacitors, inductors, and other filtering circuitry for processing received signals, and circuitry for modulating and / or demodulating signals according to a communication protocol. The communication circuit 110 may also include transistors or other switching circuitry for selectively coupling a transmitted signal to an antenna (not shown) of the IMD 4 or an electrode 116 or receiving a signal from the antenna or the electrode. Under the control of the processing circuit 102, the communication circuit 110 may receive downlink telemetry from the external device 8 or another device and transmit uplink telemetry to the external device or another device. A patient, clinician, or another user may use the external device 8 or retrieve data from the IMD 4 by using another local or networked computing device (e.g., a remote computer located with the clinician) configured to communicate with the processing circuit 102 via the communication circuit 110. In some examples, the clinician may also use the external device 8 to program parameters of the IMD 4.

[0037] The IMD 4 is an example of a device configured to determine whether electrical stimulation has achieved CSP (e.g., LBBP) or alternatively has resulted in less efficient myocardial pacing (e.g., LVSP). The therapy delivery circuit 106 is configured to deliver electrical stimulation that is configured to provide, for example, LBBAP via electrodes 34 ( Figure 1 and Figure 2 ). The processing circuit 102 is configured to execute a CSP discriminator 120 to determine whether the electrical stimulation has resulted in CSP or myocardial pacing.

[0038] The processing circuit 102 is configured to control the sensing circuit 104 to sense one or more EGMs and ventricular activations (e.g., left ventricular activation, left ventricular septal activation, etc.) caused by the electrical stimulation via one or more electrodes 116. The processing circuit 102 is configured to determine one or more conduction metrics 122 based on the sensed one or more ventricular activations. The processing circuit 102 determines whether the electrical stimulation has provided CSP, such as LBBP, based on the one or more conduction metrics.

[0039] Figure 4is a functional block diagram of an exemplary system that includes an access point 140, a network 142, an external computing device, such as an external device (server) 144 that may include a memory 146 and / or processing circuitry 148, and one or more other computing devices 150A through 150N that may be coupled to the IMD 4 and the external device 8 via the network 142. In this example, the IMD 4 may use the communication circuitry 110 to communicate with the external device 8 via a first wireless connection and with the access point 140 via a second wireless connection. In Figure 4 the example, the access point 140, the external device 8, the server 144, and the computing devices 150A through 150N are interconnected and may communicate with each other via the network 142.

[0040] The access point 140 may include a device that is connected to the network 142 via any of a variety of connections, such as a telephone dial-up, digital subscriber line (DSL), or cable modem connection, or other suitable connection. In other examples, the access point 140 may be coupled to the network 142 via different forms of connections, including wired or wireless connections. In some examples, the access point 140 may be a user device that may be co-located with a patient, such as a tablet or a smart phone. As discussed above, the IMD 4 may be configured to transmit data, such as current values and heart failure status, to the external device 8. Additionally, the access point 140 may interrogate the IMD 4, such as periodically or in response to a command from the patient, a clinician, or the network 142, to retrieve data related to one or more of patient parameters, therapy delivery, or other information stored in the memory 112 of the IMD 4 ( Figure 3 ). The access point 140 may then transmit the retrieved data to the server 144 via the network 142.

[0041] In some cases, the memory 146 of the server 144 may be configured to provide a secure storage site for data collected from the IMD 4 and / or the external device 8. In some cases, the server 144 may compile the data in a web page or other document via the computing devices 150A - 150N for viewing by trained professionals, such as clinicians. Figure 4 One or more aspects of the illustrated system may be implemented using general network technologies and functionality that may include or be similar to the general network technologies and functionality provided by a Medtronic network developed by Medtronic, Inc., of Dublin, Ireland. In some examples, such network technologies and functionality may enhance the Figure 4The security of communications transmitted between components (such as communications transmitted from external device 8 to IMD 4). For example, network technologies and functions can verify communications transmitted from a device claiming to be external device 8 and directed to IMD 4 by verifying the identity of the device claiming to be external device 8, such as patient or clinician input. In other examples, network technologies and functions can similarly verify communications transmitted to IMD 4 from another device, such as one or more of computing devices 150A - 150N (e.g., a claimed remote computer located with a clinician). In some instances, such security features can protect cardiac pacing delivered by IMD 4 to a patient from being disrupted, hacked, or otherwise altered by communications from unauthorized sources. In some instances, one or more of computing devices 150A - 150N (e.g., device 150A) can be a remote computer, such as a smart phone, tablet, or other smart device located with a clinician, through which the clinician can program, receive alerts from, and / or interrogate IMD 4.

[0042] Figures 5A to 5B is a conceptual diagram illustrating the sensing of ventricular activation by sensing circuit 104. Figure 5A Illustrates sensed left ventricular activation 212 detected by an electrode (e.g., electrode 48) of second lead 14 in response to a first pulse 210 delivered, for example, via electrode 34 of first lead 12. In the illustrated example, first pulse 210 is an LBBAP pulse (e.g., an LBBP pulse or an LVSP pulse). As Figure 5A shown, first pulse 210 can travel along the His - Purkinje fibers of the LBB (e.g., an LBBP pulse) to rapidly activate LV 28 and reach electrode 48, or first pulse 210 can travel more slowly along the ventricular septal wall via myocardial tissue to activate LV 28 and reach electrode 48. In either case, the time from first pacing pulse 210 to the detection point of second lead 14 is represented by first conduction time 224.

[0043] Figure 5B Illustrates left ventricular activation 222 detected by an electrode (e.g., electrode 34) of first lead 12 in response to a second pulse 220 delivered, for example, via electrode 48 of second lead 14. As Figure 5B shown, second pulse 220 can travel more slowly from the LV free wall of the CS through myocardial tissue to the LBB region and reach electrode 34 after second conduction time 224.

[0044] According to the technology of the present disclosure, the sensing circuit 104 may be configured to sense a first depolarization generated by a first pacing pulse delivered by one or more electrodes of a first set of electrodes carried by the first lead 12 via one or more electrodes of a second set of electrodes carried by the second lead 14. For example, the sensing circuit 104 may be configured to sense a left ventricular activation 212 caused by the first pulse 210 delivered by the electrode 34 via the electrode 48. The electrode 34 may deliver the first pulse 210 near the LBB, and the electrode 48 may sense the left ventricular activation 212 at the CS after a first conduction time 214. Additionally, the sensing circuit 104 may be configured to sense a second depolarization generated by a second pacing pulse delivered by one or more electrodes of a second set of electrodes carried by the second lead 14 via one or more electrodes of a first set of electrodes carried by the first lead 12. For example, the sensing circuit 104 may be configured to sense a left ventricular activation 222 caused by the second pulse 220 delivered by the electrode 48 via the electrode 34. The electrode 48 may deliver the second pulse 220 to the LV at the CS, and the electrode 34 may sense the left ventricular septal activation 222 at the LBB after a second conduction time 224.

[0045] The processing circuit 102 may be configured to execute a CSP discriminator 120 to determine whether an electrical stimulation results in CSP or myocardial pacing. For example, the CSP discriminator 120 may determine a first conduction time 214 of a first pacing pulse from an LBB region (e.g., left ventricular septum, septal myocardium, etc.) to the LV near the CS based on the sensing of the first depolarization. As used herein, the conduction time may refer to the time interval during which a signal (such as a pacing pulse) conducts (e.g., advances) from a first location (e.g., LBB) in the heart 6 to a second location (e.g., CS) in the heart 6. For example, the CSP discriminator 120 may determine the first conduction time 214 by calculating the time interval from when the first pulse 210 is delivered by the electrode 34 at the LBB to when the left ventricular activation 212 is sensed by the electrode 48 at the CS.

[0046] Additionally, the CSP discriminator 120 may determine a second conduction time 224 of a second pacing pulse from the CS to the LBB based on the sensing of the second depolarization. For example, the CSP discriminator 120 may determine the second conduction time 214 by calculating the time interval from when the second pulse 220 is delivered by the electrode 48 at the CS to when the left ventricular activation 222 is sensed by the electrode 34 at the LBB.

[0047] The CSP discriminator 120 can determine whether an LBBAP pulse (e.g., a first pacing pulse) includes successful LBBP rather than myocardial capture (e.g., LVSP) based on the first conduction time 214 and the second conduction time 224. In some examples, the CSP discriminator 120 can determine whether the LBBAP pulse includes LBB capture based on the difference between the second conduction time 224 minus the first conduction time 214 being greater than or equal to a conduction time difference threshold, which can be represented by the equation T 2 -T 1 ≥x, where T 1 is the first conduction time 214, where T 2 is the second conduction time 224, and where x is the conduction time difference threshold (e.g., 15 milliseconds (ms), 20 ms, 25 ms, etc.). For example, when the equation T 2 -T 1 ≥x is true, the CSP discriminator 120 can determine that the LBBAP pulse includes LBBP. Conversely, when the equation T 2 -T 1 ≥x is false, the CSP discriminator 120 can determine that the LBBAP pulse does not include LBBP (and instead includes myocardial pacing, such as LVSP).

[0048] The processing circuit 102 can perform one or more operations in response to the CSP discriminator 120 determining whether the described CSP discrimination detects LBB capture. For example, in response to the CSP discriminator 120 determining that the electrode 34 provides LBBP, the processing circuit 102 can further configure the delivery of the CSP by determining the atrioventricular (AV) delay length based on the first conduction time 214 or other metrics or cardiac synchrony or performance (such as QRS width or other QRS shape metrics). For example, the processing circuit 102 can iteratively select an AV delay length from a range of AV delay lengths, deliver the CSP using the selected AV length, and determine the corresponding first conduction time. The processing circuit 102 can then determine the AV delay length that results in the first conduction time closest to a preferred value or the shortest, and use the AV delay length for the CSP. In other words, the processing circuit 102 can determine a corresponding first conduction time among a plurality of first conduction times for each of a plurality of AV delays, and select one of the AV delays based on the plurality of first conduction times.

[0049] Additionally or alternatively, the processing circuit 102 may determine the AV delay length based on the QRS width (or other metrics, such as the QRS morphology metric). For example, the processing circuit 102 may iteratively select an AV delay length from an AV delay length range, deliver the CSP using the selected AV length, and determine the corresponding QRS width. The processing circuit 102 may select the AV delay length corresponding to the shortest QRS width. The processing circuit 102 may follow a similar procedure for other morphology metrics.

[0050] In another example, in response to the CSP discriminator 120 determining that the LBBAP pulse does not suggest LBBP, the processing circuit 102 may be configured to confirm this determination by determining whether the first conduction time 214 is greater than or equal to a first conduction time threshold (e.g., 75 ms, 80 ms, 85 ms, etc.). The determination that the first conduction time 214 is greater than or equal to the first conduction time threshold may confirm that the LBBAP pulse does not include LBBP and is not undergoing CSP therapy. Thus, in response to the CSP discriminator 120 determining that the first conduction time 214 is greater than or equal to the first conduction time threshold, the processing circuit 102 may be configured to control the delivery of biventricular CRT pacing via the first set of electrodes and the second set of electrodes. For example, the processing circuit 102 may be configured to cause the first set of electrodes of the first lead 12 and the second set of electrodes of the second lead 14 to deliver biventricular CRT pacing, such as left bundle branch optimized cardiac resynchronization therapy (LOT-CRT). LOT-CRT may include LVSP and LV-CS pacing.

[0051] Biventricular CRT may include delaying the pacing pulse delivered via the second set of electrodes of the second lead 14 relative to the pacing pulse delivered via the first set of electrodes of the first lead 12 by a left ventricular pacing pulse delay length. In some examples, the processing circuit 102 may be configured to determine the left ventricular pacing pulse delay length based on the equation 1.5*y – T 1 = z, where y is a reference conduction time (e.g., 80 ms, 85 ms, 90 ms, etc.) representing the theoretical conduction time from the LBB (e.g., left ventricular septum) to the CS, where T 1 is the first conduction time, and where z is the left ventricular pacing pulse delay length. This equation may reduce or eliminate ventricular asynchrony (e.g., differences in the timing of contractions or lack of synchronization in different ventricles of the heart 6). The reference conduction time may be a predetermined value (e.g., determined based on empirical data) indicating the typical (e.g., average, normal, common, etc.) time interval for a signal to conduct from the LBB to the CS via the heart's natural conduction system. In some examples, the left ventricular pacing pulse delay length z may be set to a value between approximately 1 / 2T 1 and 1 / 2y. In any case, delaying the left ventricular pacing pulse delay length according to the techniques of the present disclosure may advantageously reduce or eliminate ventricular asynchrony, thereby improving patient outcomes.

[0052] Conversely, the determination that the first conduction time 214 is less than the first conduction time threshold may indicate that the earlier determination that the LBBAP pulse does not include the LBBP is incorrect and that CSP capture is in progress. Thus, in some examples, in response to the CSP discriminator 120 determining that the first conduction time 214 is less than the first conduction time threshold, the processing circuit 102 may be configured to determine the AV delay length based on the first conduction time 214 as described above to provide CSP.

[0053] It should be understood that the positions of the first set of electrodes and the second set of electrodes may affect the first conduction time 214 and the second conduction time 224. Accordingly, the present disclosure contemplates deviations from the values of the equations, thresholds, etc. described above that may be attributable to variations in the positions of the first set of electrodes and the second set of electrodes.

[0054] Figure 6 is a flowchart illustrating exemplary operations for differentiating conduction system pacing from myocardial pacing according to the techniques of the present disclosure. Figure 6 The exemplary techniques are described as being performed by the medical device system 2 including the IMD 4. In some examples, Figure 6 the techniques may be performed by other systems including other devices. For example, Figure 6 the techniques may be performed by an external diagnostic device, such as a pacing system analyzer (PSA) that is coupled to the leads 12, 14, 16 during implantation thereof and prior to their being coupled to the IMD 4.

[0055] The IMD 4 may deliver a first pacing pulse (300) via a first set of electrodes of the first lead 12. For example, the processing circuit 102 may control the therapy delivery circuit 106 to deliver electrical stimulation (e.g., the first pulse 210) via the electrode 34 at the LBB. The processing circuit 102 may control the sensing circuit 104 to sense a first depolarization (302) generated by the first pacing pulse via a second set of electrodes of the second lead 14. For example, the sensing circuit 104 may sense the left ventricular activation 212 generated by the first pulse 210 via the electrode 48 positioned at the CS.

[0056] The IMD 4 may deliver a second pacing pulse (304) via a second set of electrodes of the second lead 14. For example, the processing circuit 102 may control the therapy delivery circuit 106 to deliver electrical stimulation (e.g., the second pulse 220) via the electrode 48 at the CS. The processing circuit 102 may control the sensing circuit 104 to sense a second depolarization (306) generated by the second pacing pulse via a first set of electrodes of the first lead 12. For example, the sensing circuit 104 may sense the left ventricular septal activation 222 generated by the second pulse 220 via the electrode 34 positioned at the LBB.

[0057] The CSP discriminator 120 may determine a first conduction time 214 (308) of a first pacing pulse from the LBB to the CS based on sensing of a first depolarization. For example, the CSP discriminator 120 may determine the first conduction time 214 by calculating the time interval from delivery of the first pulse 210 at the LBB by electrode 34 to sensing of left ventricular activation 212 at the CS by electrode 48.

[0058] The CSP discriminator 120 may determine a second conduction time 224 (310) of a second pacing pulse from the CS to the LBB region based on sensing of a second depolarization. For example, the CSP discriminator 120 may determine the second conduction time 214 by calculating the time interval from delivery of the second pulse 220 at the CS by electrode 48 to sensing of left ventricular septal activation 222 at the LBB by electrode 34.

[0059] The CSP discriminator 120 may determine whether an LBBAP pulse includes a successful LBBP (312) based on the first conduction time 214 and the second conduction time 224. In some examples, the CSP discriminator 120 may determine whether an LBBAP pulse includes LBB capture based on the equation T 2 -T 1 ≥x, where T 1 is the first conduction time 214, where T 2 is the second conduction time 224, and where x is a conduction time difference threshold (e.g., 15 milliseconds (ms), 20 ms, 25 ms, etc.). For example, when the equation T 2 -T 1 ≥x is true, the CSP discriminator 120 may determine that the LBBAP pulse includes LBBP. Conversely, when the equation T 2 -T 1 ≥x is false, the CSP discriminator 120 may determine that the LBBAP pulse does not include LBB capture (and instead includes myocardial pacing, such as LVSP).

[0060] In response to the CSP discriminator 120 determining that the LBBAP pulse includes LBBP (the "yes" box of 312), the processing circuit 102 may cause the therapy delivery circuit 106 to deliver CSP (314). In some examples, the processing circuit 102 may optimize delivery of CSP by determining an AV delay length based on the first conduction time 214. For example, the processing circuit 102 may iteratively select an AV delay length from a range of AV delay lengths and determine the corresponding first conduction time. The processing circuit 102 may then determine the AV delay length that results in a first conduction time closest to a preferred value and use the AV delay length for CSP. Additionally or alternatively, the processing circuit 102 may determine the AV delay length based on the QRS width (or other morphological metric).

[0061] In response to the CSP discriminator 120 determining that the LBBAP pulse does not include an LBB capture (the "No" box of 312), the processing circuitry 102 may cause the therapy delivery circuitry 106 to deliver biventricular CRT (316). In some examples, the processing circuitry 102 may determine the left ventricular pacing pulse delay length for biventricular CRT based on the equation 1.5*y – T 1 = z, where y is the reference conduction time from the LBB to the CS (e.g., 80 ms, 85 ms, 90 ms, etc.), where T 1 is the first conduction time, and where z is the left ventricular pacing pulse delay length. This equation may reduce or eliminate ventricular asynchrony, which can improve patient outcomes.

[0062] In some examples, after the CSP discriminator 120 determines that the LBBAP pulse does not include an LBBP (the "No" box of 312) and before delivering biventricular CRT (316), the CSP discriminator 120 may confirm the determination that the LBBAP pulse does not include an LBBP by determining whether the first conduction time 214 is greater than or equal to a first conduction time threshold (e.g., 75 ms, 80 ms, 85 ms, etc.). The determination that the first conduction time 214 is greater than or equal to the first conduction time threshold may confirm that the LBBAP pulse does not include an LBBP and that CSP is not in progress. Accordingly, in response to the CSP discriminator 120 determining that the first conduction time 214 is greater than or equal to the first conduction time threshold, the processing circuitry 102 may cause the therapy delivery circuitry 106 to deliver CRT (316). Conversely, the determination that the first conduction time 214 is less than the first conduction time threshold may indicate that the earlier determination that the LBBAP pulse does not include an LBBP was incorrect and that CSP is in progress. Accordingly, in response to the CSP discriminator 120 determining that the first conduction time 214 is less than the first conduction time threshold, the processing circuitry 102 may cause the therapy delivery circuitry 106 to deliver CSP (314).

[0063] Aspects of these techniques may be implemented within one or more processors, including one or more microprocessors, DSPs, ASICs, FPGAs, or any other equivalent integrated or discrete logic circuitry, as well as any combination of such components, embodied in a programmer such as a doctor or patient programmer, an electrical stimulator, or other device. The term "processor" or "processing circuitry" generally may refer to any of the foregoing logic circuitry, alone or in combination with other logic circuitry or any other equivalent circuitry.

[0064] In one or more examples, the functions described in this disclosure may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, the functions may be stored on a computer-readable medium as one or more instructions or code and executed by a hardware-based processing unit. The computer-readable medium may include a computer-readable storage medium that forms a tangible non-transitory medium. The instructions may be executed by one or more processors, such as one or more DSPs, ASICs, FPGAs, general-purpose microprocessors, or other equivalent integrated or discrete logic circuitry. Thus, the term "processor" or "processing circuit" as used herein may refer to any one or more of the foregoing structures or any other structure suitable for implementing the techniques described herein.

[0065] In addition, in some aspects, the functionality described herein may be provided within dedicated hardware and / or software modules. Describing different features as modules or units is intended to highlight different functional aspects and does not necessarily imply that such modules or units must be implemented by separate hardware or software components. Instead, the functions 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. Additionally, these techniques may be implemented entirely in one or more circuits or logic elements. The techniques of this disclosure may be implemented in various devices or apparatuses, including an IMD, an external programmer, a combination of an IMD and an external programmer, an integrated circuit (IC) or a set of ICs, and / or discrete circuitry residing within the IMD and / or the external programmer.

[0066] Furthermore, the functions and techniques described in this disclosure may be provided by a medical device system that includes multiple IMDs. In some such instances, an IMD that may be controlled by a processing circuit to deliver ventricular pacing may not include sensing electrodes through which the processing circuit obtains electrograms. For example, some such medical device systems may include lead-based IMDs that include one or more intravascular leads, or an extracorporeal ICD may include electrodes that, in combination with an LPD configured to be placed on or within the left ventricle and deliver ventricular pacing thereto, form a first electrode vector and a second electrode vector.

[0067] In some such instances, the processing circuit of the medical device system (e.g., the processing circuit of a lead-based IMD or an extracorporeal IMD) may control the LPD to deliver ventricular pacing at a series of A-LV delays. The lead-based IMD or the extracorporeal IMD may detect the pacing pulses delivered by the LPD and the resulting ventricular activation in the electrodes obtained by the processing circuit from the first electrode vector and the second electrode vector. Then, the processing circuit may determine updated values of the CRT parameters according to the techniques described herein and control the LPD to deliver LV pacing at the updated values of the CRT parameters to provide CRT.

[0068] Various aspects of the disclosure have been described. These aspects, and others, are within the scope of the following claims.

[0069] The following examples are a non - limiting list of articles according to one or more techniques of the disclosure.

[0070] Example 1. An implantable medical device, the implantable medical device comprising: a connector block configured to be coupled to a plurality of leads, the plurality of leads including a first lead that carries a first set of electrodes and is configured to be implanted in the interventricular septum of the heart to position at least one of the first set of electrodes in the left bundle branch region near the left ventricular septum; and a second lead that carries a second set of electrodes and is configured to be implanted in the coronary sinus of the heart; and a sensing circuit configured to: sense, via the second set of electrodes, a first depolarization generated by a first pacing pulse delivered by the first set of electrodes; and sense, via the first set of electrodes, a second depolarization generated by a second pacing pulse delivered by the second set of electrodes; and a processing circuit configured to: determine, based on the sensing of the first depolarization, a first conduction time of the first pacing pulse from the left ventricular septum to the coronary sinus; determine, based on the sensing of the second depolarization, a second conduction time of the second pacing pulse from the coronary sinus to the left ventricular septum; and determine, based on the first conduction time and the second conduction time, whether the first pacing pulse includes left bundle branch pacing.

[0071] Example 2. The implantable medical device according to Example 1, wherein the processing circuit is configured to determine whether the first pacing pulse includes left bundle branch pacing by determining whether a difference between the second conduction time and the first conduction time is greater than or equal to a conduction time difference threshold.

[0072] Example 3. The implantable medical device according to Example 2, wherein the conduction time difference threshold is 20 milliseconds.

[0073] Example 4. The implantable medical device according to any one of Examples 1 to 3, wherein the processing circuit is further configured to: in response to determining that the first pacing pulse includes left bundle branch pacing, determine a corresponding first conduction time among a plurality of first conduction times for each of a plurality of atrioventricular delays; and select one of the atrioventricular delays based on the plurality of first conduction times.

[0074] Example 5. The implantable medical device according to any one of Examples 1 to 4, wherein the processing circuit is further configured to: in response to determining that the first pacing pulse does not include left bundle branch pacing, determine whether the first conduction time is greater than or equal to a first conduction time threshold; and in response to determining that the first conduction time is greater than or equal to the first conduction time threshold, control the delivery of cardiac resynchronization therapy via the first set of electrodes and the second set of electrodes.

[0075] Example 6. The implantable medical device according to Example 5, wherein the cardiac resynchronization therapy includes delaying a left ventricular pacing pulse by a left ventricular pacing pulse delay length with respect to the pacing pulse delivered via the first set of electrodes.

[0076] Example 7. The implantable medical device according to Example 6, wherein the processing circuit is configured to determine the left ventricular pacing pulse delay length based on the equation 1.5*y – T 1 = z, where y is a reference conduction time from the left ventricular septum to the coronary sinus, where T 1 is the first conduction time, and where z is the left ventricular pacing pulse delay length.

[0077] Example 8. The implantable medical device according to Example 7, wherein the reference conduction time is about 85 milliseconds.

[0078] Example 9. The implantable medical device according to any one of Examples 5 to 8, wherein the first conduction time threshold is 85 milliseconds.

[0079] Example 10. The implantable medical device according to any one of Examples 5 to 9, wherein the processing circuit is further configured to: in response to determining that the first conduction time is less than the first conduction time threshold, determine a corresponding first conduction time among a plurality of first conduction times for each atrioventricular delay of a plurality of atrioventricular delays; and select one atrioventricular delay from among the atrioventricular delays based on the plurality of first conduction times.

[0080] Example 11. A medical system, the medical system comprising: a plurality of leads, the plurality of leads including: a first lead that carries a first set of electrodes and is configured to be implanted in the interventricular septum of the heart to position at least one of the first set of electrodes in the left bundle branch region near the left ventricular septum; and a second lead that carries a second set of electrodes and is configured to be implanted in the coronary sinus of the heart; an implantable medical device coupled to the plurality of leads, the implantable medical device including: a sensing circuit configured to: sense, via the second set of electrodes, a first depolarization generated by a first pacing pulse delivered by the first set of electrodes; and sense, via the first set of electrodes, a second depolarization generated by a second pacing pulse delivered by the second set of electrodes; and a processing circuit configured to: determine a first conduction time of the first pacing pulse from the left ventricular septum to the coronary sinus based on the sensing of the first depolarization; determine a second conduction time of the second pacing pulse from the coronary sinus to the left ventricular septum based on the sensing of the second depolarization; and determine whether the first pacing pulse includes left bundle branch pacing based on the first conduction time and the second conduction time; and an external device configured to: be communicatively coupled to the implantable medical device; and output an indication of whether the first pacing pulse includes left bundle branch pacing.

[0081] Example 12. The medical system according to Example 11, wherein the processing circuit is configured to determine whether the first pacing pulse includes left bundle branch pacing by determining whether a difference between the second conduction time and the first conduction time is greater than or equal to a conduction time difference threshold.

[0082] Example 13. The medical system according to Example 12, wherein the conduction time difference threshold is 20 milliseconds.

[0083] Example 14. The medical system according to any one of Examples 11 to 13, wherein the processing circuit is further configured to: in response to determining that the first pacing pulse includes left bundle branch pacing, determine a corresponding first conduction time among a plurality of first conduction times for each of a plurality of atrioventricular delays; and select one of the atrioventricular delays based on the plurality of first conduction times.

[0084] Example 15. The medical system according to any one of Examples 11 to 14, wherein the processing circuit is further configured to: in response to determining that the first pacing pulse does not include left bundle branch pacing, determine whether the first conduction time is greater than or equal to a first conduction time threshold; and in response to determining that the first conduction time is greater than or equal to the first conduction time threshold, control the delivery of cardiac resynchronization therapy via the first set of electrodes and the second set of electrodes.

[0085] Example 16. The medical system according to Example 15, wherein the cardiac resynchronization therapy includes delaying a left ventricular pacing pulse delay length of a pacing pulse delivered via the second set of electrodes relative to a pacing pulse delivered via the first set of electrodes.

[0086] Example 17. The medical system according to Example 16, wherein the processing circuit is configured to determine the left ventricular pacing pulse delay length based on the equation 1.5*y – T 1 = z, where y is a reference conduction time from the left ventricular septum to the coronary sinus, where T 1 is the first conduction time, and where z is the left ventricular pacing pulse delay length.

[0087] Example 18. The medical system according to Example 17, wherein the reference conduction time is about 85 milliseconds.

[0088] Example 19. The medical system according to any one of Examples 15 to 18, wherein the first conduction time threshold is 85 milliseconds.

[0089] Example 20. The medical system according to any one of Examples 15 to 19, wherein the processing circuit is further configured to: in response to determining that the first conduction time is less than the first conduction time threshold, determine a corresponding first conduction time among a plurality of first conduction times for each atrioventricular delay of the plurality of atrioventricular delays; and select one atrioventricular delay of the atrioventricular delays based on the plurality of first conduction times.

[0090] Example 21. A method, the method comprising: sensing, via a second set of electrodes of a second lead of an implantable medical device, a first depolarization generated by a first pacing pulse delivered by a first set of electrodes of a first lead of the implantable medical device, wherein the second set of electrodes is positioned in the coronary sinus, wherein the first set of electrodes is implanted in the ventricular septum of the heart, and wherein at least one electrode of the first set of electrodes is in the left bundle branch region near the left ventricular septum; and sensing, via the first set of electrodes, a second depolarization generated by a second pacing pulse delivered by the second set of electrodes; determining, by a processing circuit of the implantable medical device, a first conduction time of the first pacing pulse from the left ventricular septum to the coronary sinus based on the sensing of the first depolarization; determining, by the processing circuit, a second conduction time of the second pacing pulse from the coronary sinus to the left ventricular septum based on the sensing of the second depolarization; and determining, by the processing circuit, whether the first pacing pulse includes left bundle branch pacing based on the first conduction time and the second conduction time.

[0091] Example 22. The method according to Example 21, wherein determining whether the first pacing pulse includes left bundle branch pacing includes determining, by the processing circuit, whether a difference between the second conduction time and the first conduction time is greater than or equal to a conduction time difference threshold.

[0092] Example 23. The method according to Example 22, wherein the conduction time difference threshold is 20 milliseconds.

[0093] Example 24. The method according to any one of Examples 21 to 23, the method further comprising: determining, by the processing circuit, a corresponding first conduction time among a plurality of first conduction times for each atrioventricular delay in response to determining that the first pacing pulse includes left bundle branch pacing; and selecting, by the processing circuit, one of the atrioventricular delays based on the plurality of first conduction times.

[0094] Example 25. The method according to any one of Examples 21 to 24, the method further comprising: determining, by the processing circuit, whether the first conduction time is greater than or equal to a first conduction time threshold in response to determining that the first pacing pulse does not include left bundle branch pacing; and controlling, by the processing circuit, delivery of cardiac resynchronization therapy via the first set of electrodes and the second set of electrodes in response to determining that the first conduction time is greater than or equal to the first conduction time threshold.

[0095] Example 26. The method according to Example 25, wherein the cardiac resynchronization therapy includes delaying a left ventricular pacing pulse by a left ventricular pacing pulse delay length with respect to a pacing pulse delivered via the first set of electrodes.

[0096] Example 27. The method according to Example 26, wherein determining the left ventricular pacing pulse delay length includes determining, by the processing circuit, the left ventricular pacing pulse delay length based on Equation 1.5*y – T 1 = z to determine the left ventricular pacing pulse delay length, where y is a reference conduction time from the left ventricular septum to the coronary sinus, where T 1 is the first conduction time, and where z is the left ventricular pacing pulse delay length.

[0097] Example 28. The method according to Example 27, wherein the reference conduction time is about 85 milliseconds.

[0098] Example 29. The method according to any one of Examples 25 to 28, wherein the first conduction time threshold is 85 milliseconds.

[0099] Example 30. The method according to any one of Examples 25 to 29, the method further comprising: determining, by the processing circuit, a respective first conduction time among a plurality of first conduction times for each of a plurality of atrioventricular delays in response to determining that the first conduction time is less than the first conduction time threshold; and selecting, by the processing circuit, one of the atrioventricular delays based on the plurality of first conduction times.

Claims

1. An implantable medical device, the implantable medical device comprising: A connector block configured to be coupled to a plurality of leads, the plurality of leads including: A first lead that carries a first set of electrodes and is configured to be implanted in the interventricular septum of the heart to position at least one of the first set of electrodes in the left bundle branch region near the left ventricular septum; and A second lead that carries a second set of electrodes and is configured to be implanted in the coronary sinus of the heart; and A sensing circuit configured to: Sense a first depolarization generated by a first pacing pulse delivered by the first set of electrodes via the second set of electrodes; and Sense a second depolarization generated by a second pacing pulse delivered by the second set of electrodes via the first set of electrodes; and A processing circuit configured to: Determine a first conduction time of the first pacing pulse from the left ventricular septum to the coronary sinus based on the sensing of the first depolarization; Determine a second conduction time of the second pacing pulse from the coronary sinus to the left ventricular septum based on the sensing of the second depolarization; and Determine whether the first pacing pulse includes left bundle branch pacing based on the first conduction time and the second conduction time.

2. The implantable medical device according to claim 1, wherein the processing circuit is configured to determine whether the first pacing pulse includes left bundle branch pacing by determining whether the difference between the second conduction time and the first conduction time is greater than or equal to a conduction time difference threshold.

3. The implantable medical device according to claim 2, wherein the conduction time difference threshold is 20 milliseconds.

4. The implantable medical device according to any one of claims 1 to 3, wherein the processing circuit is further configured to: In response to determining that the first pacing pulse includes left bundle branch pacing, determine a corresponding first conduction time among a plurality of first conduction times for each of a plurality of atrioventricular delays; and Select one of the atrioventricular delays based on the plurality of first conduction times.

5. The implantable medical device according to any one of claims 1 to 4, wherein the processing circuit is further configured to: In response to determining that the first pacing pulse does not include left bundle branch pacing, determine whether the first conduction time is greater than or equal to a first conduction time threshold; and In response to determining that the first conduction time is greater than or equal to the first conduction time threshold, control the delivery of cardiac resynchronization therapy via the first set of electrodes and the second set of electrodes.

6. The implantable medical device according to claim 5, wherein the cardiac resynchronization therapy includes delaying a pacing pulse delivered via the second set of electrodes by a left ventricular pacing pulse delay length relative to a pacing pulse delivered via the first set of electrodes.

7. The implantable medical device according to claim 6, wherein the processing circuit is configured to determine the left ventricular pacing pulse delay length based on the equation 1.5*y - T 1 = z, where y is a reference conduction time from the left ventricular septum to the coronary sinus, where T 1 is the first conduction time, and where z is the left ventricular pacing pulse delay length.

8. The implantable medical device according to claim 7, wherein the reference conduction time is about 85 milliseconds.

9. The implantable medical device according to any one of claims 5 to 8, wherein the first conduction time threshold is 85 milliseconds.

10. The implantable medical device according to any one of claims 5 to 9, wherein the processing circuit is further configured to: in response to determining that the first conduction time is less than the first conduction time threshold, determine a corresponding first conduction time among the plurality of first conduction times for each atrioventricular delay among the plurality of atrioventricular delays; and select one atrioventricular delay among the atrioventricular delays based on the plurality of first conduction times.

11. A medical system, the medical system comprising: the implantable medical device according to any one of the foregoing claims; a plurality of leads, the plurality of leads including a first lead and a second lead, the implantable medical device being coupled to the plurality of leads; and an external device, the external device being configured to: communicatively couple to the implantable medical device; and output an indication of whether the first pacing pulse includes left bundle branch pacing.

12. A method, the method comprising: sensing, via a second set of electrodes of a second lead of an implantable medical device, a first depolarization generated by a first pacing pulse delivered by a first set of electrodes of a first lead of the implantable medical device, wherein the second set of electrodes is positioned in the coronary sinus, wherein the first set of electrodes is implanted in the interventricular septum of the heart, and wherein at least one electrode of the first set of electrodes is located in the left bundle branch region near the left ventricular septum; and sensing, via the first set of electrodes, a second depolarization generated by a second pacing pulse delivered by the second set of electrodes; determining, by a processing circuit of the implantable medical device, a first conduction time of the first pacing pulse from the left ventricular septum to the coronary sinus based on the sensing of the first depolarization; determining, by the processing circuit, a second conduction time of the second pacing pulse from the coronary sinus to the left ventricular septum based on the sensing of the second depolarization; and determining, by the processing circuit, whether the first pacing pulse includes left bundle branch pacing based on the first conduction time and the second conduction time.

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