Cardiac conduction system pacing therapy adjustment

Abstract

Illustrative systems, devices, and methods monitor cardiac morphology during delivery of cardiac conduction system pacing therapy to determine effective cardiac conduction system pacing therapy. If effective cardiac conduction system pacing therapy is not determined, one or both of the cardiac conduction system pacing vector and atrioventricular delay may be adjusted until the monitored cardiac morphology indicates effective cardiac conduction system pacing therapy.

Description

MRG Docket No. 0134.001353W001 Medtronic Docket No. A0012625W001CARDIAC CONDUCTION SYSTEM PACING THERAPY ADJUSTMENT

[0001] This application claims priority to U.S. Provisional Patent Application Serial No. 63 / 736,208, filed December 19, 2024, the disclosure of which is incorporated herein by reference.

[0002] The present disclosure relates to adjustment of cardiac conduction system pacing therapy based on cardiac morphology.

[0003] Implantable medical devices (IMDs), such as cardiac pacemakers or implantable cardioverter defibrillators, deliver therapeutic stimulation to patients’ hearts thereby improving the lives of millions of patients living with heart conditions. Conventional pacing techniques involve pacing one or more of the four chambers of a patient’s heart 12 as illustrated in FIG. 1, including the left atrium 33, the right atrium 26, the left ventricle 32 and the right ventricle 28. One common conventional therapeutic pacing technique that treats a slow heart rate, referred to as bradycardia, involves delivering an electrical pulse to a patient’s right ventricular tissue. In response to the electrical pulse, both the right and left ventricles contract. However, the heart beat process may be significantly delayed because the pulse travels from the right ventricle through the left ventricle. The electrical pulse passes through the muscle cells that are referred to as myocytes. Myocyte-to-myocyte conduction may be very slow. Delayed electrical pulses can cause the left ventricle to be unable to maintain synchrony with the right ventricle.

[0004] Over time, the left ventricle can become significantly inefficient at pumping blood to the body. In some patients, heart failure can develop such that the heart is too weak to pump blood to the body. Heart failure may be a devastating diagnosis since, for example, fifty percent of the heart failure patients have a life expectancy of five years or less. Another possible cause of heart failure is due to atrial fibrillation, which is an irregular and often very rapid heart rhythm or arrhythmia. During atrial fibrillation, the atria of the heart can beat out of sync with the ventricles of the heart because of the arrythmia of the atria, which can lead to blood clots in the heart and increase the risk of stroke or heart failure, for example.

[0005] To avoid potential development of heart failure, some physicians have considered alternative pacing methods that involve the cardiac conduction system. Pacing the cardiac conduction system may quickly conduct electrical pulses (for example, akin to a car drivingon a highway), whereas pacing cardiac muscle, or myocardial, tissue may more slowly conduct electrical pulses (for example, akin to a car driving on a dirt road).

[0006] The cardiac conduction system includes the sinoatrial node 1, atrial intemodal tracts 2, 4, 5 (i.e., anterior intemodal 2, middle internodal 4, and posterior intemodal 5), atrioventricular node 3, His bundle 13 (also known as the atrioventricular bundle or bundle of His), left bundle branch 8a, and right bundle branch 8b as shown in FIG. 1. The arch of aorta 6 and the Bachman’s bundle 7 are also shown in FIG. 1. The sinoatrial node 1, located at the junction of the superior vena cava and right atrium, is considered to be the natural pacemaker of the heart as it continuously and repeatedly emits electrical impulses. The electrical impulses spread through the muscles of right atrium 26 to left atrium 33 to cause synchronous contraction of the atria. The electrical impulses are also carried through atrial internodal tracts to the atrioventricular node 3 — the sole connection between the atria and the ventricles. The conduction through the atrioventricular node or atrioventricular nodal tissue takes longer than through the atrial tissue, which results in a delay between the atrial contractions and the start of the ventricular contractions. The atrioventricular delay, which is the delay between atrial contractions and ventricular contractions, allows the atria to empty blood into the ventricles. Then, the valves between the atria and ventricles close in conjunction with ventricular contraction via branches of the bundle of His. The bundle of His, or His bundle, 13 is located in the membranous atrioventricular septum near the annulus of the tricuspid valve. The His bundle 13 splits into the left and right bundle branches 8a, 8b and are formed of specialized fibers called “Purkinje fibers” 9. The Purkinje fibers 9 may be described as being capable of rapidly conducting an action potential down the ventricular septum (VS), spreading the depolarization wavefront quickly through the remaining ventricular myocardium, and producing a coordinated contraction of the ventricular muscle mass.

[0007] Cardiac conduction system pacing therapy is widely becoming accepted in the pacing industry with the goal to mimic normal cardiac conduction as much as possible by activating the left bundle branch (LBB). When cardiac conduction system pacing activation and intrinsic activation occur at or near the same time, fusion occurs. A fused beat results in decreased effectiveness of cardiac conduction system pacing therapy.SUMMARY

[0008] The present disclosure relates to adjustment of cardiac conduction system pacing therapy, and in particular, to adjustment of cardiac conduction system pacing therapy based on determination of cardiac conduction system capture using monitored cardiac morphology. The present disclosure may be described as providing cardiac conduction system pacing therapy methods, processes, and algorithms to promote effective left bundle branch (LBB) pacing and prevent fused beats from occurring.

[0009] The present disclosure may be further described preventing ventricular fusion using dynamic methods processes, and algorithms that will continuously adjust the cardiac conduction system pacing therapy to ensure effective cardiac conduction system pacing therapy. Effective cardiac conduction system pacing therapy can be confirmed by the cardiac morphology, for example, monitored using a right ventricular lead. For example, a cardiac conduction system pacing vector may be adjusted until proper cardiac morphology (e.g., indicative of effective cardiac conduction system pacing therapy, indicative of no fusion, etc.) is monitored. In particular, adjustment of the cardiac conduction system pacing therapy may include adding or removing one or more electrodes from the cardiac conduction system pacing vector. Further, adjustment of the cardiac conduction system pacing therapy may include changing or switching the polarity (e.g., anode or cathode) of the one or more cardiac conduction system pacing electrodes. Further, adjustment of the cardiac conduction system pacing therapy may include adjusting one or more both paced and sensed AV delays, which is the time period between an atrial event, such intrinsic atrial activation or atrial pace, and delivery of a cardiac conduction system pace, until the proper cardiac morphology is monitored, circuit. Thus, the illustrative systems, methods processes, and algorithms described herein will ensure that each cardiac conduction system pacing therapy paced beat will be the most effective.

[0010] One embodiment of an illustrative implantable medical device includes a computing apparatus including processing circuitry and operably coupled to a plurality of implantable electrodes configured to sense and pace a patient's heart. The computing apparatus is configured to initiate delivery of cardiac conduction system pacing therapy using a cardiac conduction system pacing vector using a first electrode and a second electrode of the plurality of implantable electrodes. The first electrode is positioned proximate a portion of the patient's cardiac conduction system. The computing apparatus is further configured to monitor cardiac electrical activity using the plurality of implantable electrodes, determine acardiac morphology based on the cardiac electrical activity, and adjust the cardiac conduction system pacing vector based on the cardiac morphology.

[0011] One embodiment of an illustrative method includes delivering cardiac conduction system pacing therapy using a cardiac conduction system pacing vector using a first electrode and a second electrode of a plurality of implantable electrodes. The first electrode is positioned proximate a portion of the patient's cardiac conduction system. The method further includes monitoring cardiac electrical activity using the plurality of implantable electrodes, determining a cardiac morphology based on the cardiac electrical activity, and adjusting the cardiac conduction system pacing vector based on the cardiac morphology.

[0012] One embodiment of an illustrative implantable medical device includes a computing apparatus including processing circuitry and operably coupled to a plurality of implantable electrodes configured to sense and pace a patient's heart. The computing apparatus is configured to initiate delivery of cardiac conduction system pacing therapy using a cardiac conduction system pacing vector using a first electrode and a second electrode of the plurality of implantable electrodes. The first electrode is positioned proximate a portion of the patient's cardiac conduction system, and the delivery of cardiac conduction system pacing therapy is based on an atrioventricular (AV) delay. The AV delay is a time period between an atrial event and delivery of a cardiac conduction system pace of the cardiac conduction system pacing therapy. The computing apparatus is further configured to monitor cardiac electrical activity using the plurality of implantable electrodes, determine a cardiac morphology based on the cardiac electrical activity, determine whether the cardiac conduction system pacing therapy is ineffective based on the cardiac morphology, adjust AV delay in response to determination that the cardiac conduction system pacing therapy being ineffective until exhaustion of the AV delay adjustments, and adjust the cardiac conduction system pacing vector in response to exhaustion of the AV delay adjustments.

[0013] One embodiment of an illustrative method includes delivering cardiac conduction system pacing therapy using a cardiac conduction system pacing vector using a first electrode and a second electrode of a plurality of implantable electrodes. The first electrode is positioned proximate a portion of the patient’s cardiac conduction system, and the delivery of cardiac conduction system pacing therapy is based on an atrioventricular (AV) delay. The AV delay is a time period between an atrial event and delivery of a cardiac conduction system pace of the cardiac conduction system pacing therapy. The method further includesmonitoring cardiac electrical activity using the plurality of implantable electrodes, determining a cardiac morphology based on the cardiac electrical activity, and determining whether the cardiac conduction system pacing therapy is ineffective based on the cardiac morphology. The method further includes adjusting AV delay in response to determination that the cardiac conduction system pacing therapy being ineffective until exhaustion of the AV delay adjustments and adjusting the cardiac conduction system pacing vector in response to exhaustion of the AV delay adjustments.

[0014] The above summary is not intended to describe each embodiment or every implementation of the present disclosure. A more complete understanding will become apparent and appreciated by referring to the following detailed description and claims taken in conjunction with the accompanying drawings.BRIEF DESCRIPTION OF DRAWINGS

[0015] FIG. 1 is a schematic diagram of a heart and conduction system of a patient.

[0016] FIG. 2A is a conceptual diagram illustrating an illustrative therapy system that is configured to provide cardiac conduction system pacing therapy to the His bundle using a lead placed in the right atrium.

[0017] FIG. 2B is a more detailed conceptual diagram showing the illustrative therapy system of FIG. 2 A.

[0018] FIG. 3 A is a conceptual diagram illustrating an illustrative therapy system that is configured to provide cardiac conduction system pacing therapy to the left bundle branch using a lead placed in the right ventricle.

[0019] FIG. 3B is a close-up view of the lead in the patient’s heart of FIG. 3 A.

[0020] FIG. 4 is a conceptual diagram an illustrative therapy system that is configured to provide cardiac conduction system pacing therapy to the left and / or right bundle branches using a lead placed in the right ventricle.

[0021] FIG. 5 is a functional block diagram illustrating an example of a configuration of an implantable medical device of FIGS. 2-4.

[0022] FIG. 6 is a block diagram of an illustrative method of cardiac conduction system pacing therapy adjustment that may be utilized by the devices of FIGS. 2-5.

[0023] FIG. 7 is a block diagram of illustrative adjustment of cardiac conduction system pacing therapy of FIG. 6.

[0024] FIG. 8 is a block diagram of another illustrative adjustment of cardiac conduction system pacing therapy of FIG. 6.DETAILED DESCRIPTION

[0025] In the following detailed description of illustrative embodiments, reference is made to the accompanying figures of the drawing which form a part hereof, and in which are shown, by way of illustration, specific embodiments which may be practiced. It is to be understood that other embodiments may be utilized, and structural changes may be made without departing from (e.g., still falling within) the scope of the disclosure presented hereby.

[0026] Illustrative systems, devices, and methods shall be described with reference to FIGS. 1-8. It will be apparent to one skilled in the art that elements or processes from one embodiment may be used in combination with elements or processes of the other embodiments, and that the possible embodiments of such systems, devices, and methods using combinations of features set forth herein is not limited to the specific embodiments shown in the Figures and / or described herein. Further, it will be recognized that the embodiments described herein may include many elements that are not necessarily shown to scale. Still further, it will be recognized that timing of the processes and the size and shape of various elements herein may be modified but still fall within the scope of the present disclosure, although certain timings, one or more shapes and / or sizes, or types of elements, may be advantageous over others.

[0027] Conceptual diagrams showing illustrative therapy systems that may be used to provide cardiac conduction system pacing therapy to the heart 12 of a patient 14 are depicted in FIGS. 2-5. The patient 14 ordinarily, but not necessarily, will be a human. As shown in FIGS. 2A-2B, the therapy system 10 may include IMD 16, which, in this example, is coupled to three leads 18, 20, 23, and a programmer 24. The IMD 16 may be, for example, an implantable pacemaker, cardioverter, and / or defibrillator that provides electrical pulses to the heart 12 via electrodes coupled to one or more of the leads 18, 20, 23. Further non-limitingexamples of the IMD 16 include the following: a pacemaker with a medical lead, an implantable cardioverter-defibrillator (ICD), an intracardiac device, a leadless pacing device (LPD), and a subcutaneous ICD (S-ICD).

[0028] The leads 18, 20, 23 may extend into the heart 12 of the patient 14 to sense electrical activity of the heart 12 and / or deliver electrical stimulation to the heart 12. In the example shown in FIG. 2A, the right ventricular lead 18 extends through one or more veins (not shown), the superior vena cava (not shown), and the right atrium 26, and into the right ventricle 28. The left ventricular 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.

[0029] The cardiac conduction system pacing therapy lead 23 (e.g., left bundle branch pacing lead, right bundle branch pacing lead, His-bundle pacing lead, etc.) extends through one or more veins and the vena cava, and into the right atrium 26 of heart 12 to pace the cardiac conduction system (e.g., through triangle of Koch region, within the septal wall, proximate and / or in direct contact with the left bundle branch 8a, proximate and / or in direct contact with the right bundle branch 8b, proximate and / or in direct contact with the His bundle 13, etc.). In other words, the cardiac conduction system pacing lead 23 may include one or more electrodes that are positionable or implantable proximate a portion of the cardiac conduction system so as to be able deliver electrical pacing to the cardiac conduction system to activate the cardiac conduction system. In some embodiments, the cardiac conduction system pacing therapy lead 23 may be positioned within about 1 millimeter of a portion of the cardiac conduction system such as, e.g., the His bundle 13, the left bundle branch 8a, the right bundle branch 8b, etc. In one or more embodiments, a cardiac conduction system therapy lead 23 may be further positioned, or located, through the tricuspid valve into the right ventricle 28 and implanted in the interventricular septum (VS), e.g., about 1 to 2 centimeters in an apical direction as will be described further herein with reference to FIGS. 3A-3B and 4. One example of a cardiac conduction system pacing therapy lead (e.g., a His lead) can be the SELECTSECURE™ 3830. A description of the SELECT SECURE™ 3830 is found in the Medtronic model SELECTSECURE™ 3830 manual (2013), incorporated herein by reference in its entirety. The SELECTSECURE™ 3830 includes two or more conductors with or without lumens.

[0030] As used herein, cardiac conduction system pacing therapy refers to any pacing therapy configured to deliver pacing therapy (e.g., pacing pulses, electrical stimulation, etc.) to the cardiac conduction system including, e.g., the His bundle 13, the left bundle branch 8a, the right bundle branch 8b, etc. As used herein, the term “activation” refers to a sensed or paced event. For example, an atrial activation may refer to an atrial sense or event (As) or an atrial pace or artifact of atrial pacing (Ap). As will be described herein, an atrial sense may be detected, or identified, in one or more various signals monitored using one or more various devices or sensors located in one or more various locations. For example, an atrial sense may be detected in a near-field electrical signal from an electrode positioned in the right atrium. Further, for example, an atrial sense may be detected in a far-field electrical signal from an electrode positioned outside of the right atrium such as in the right ventricle or ventricular septum. Still, for example, an atrial sense may be detected in a far-field signal from a mechanical cardiac activation sensor such as an accelerometer or microphone (e.g., a heart sound sensor) positioned in the right atrium or positioned outside of the right atrium such as in the right ventricle or ventricular septum or another portion of the patient’s body. Similarly, a ventricular activation may refer to a ventricular sense or event (Vs) or a ventricular pace or artifact of ventricular pacing (Vp), which may be described as ventricular stimulation pulses. In some embodiments, an activation interval can be detected from As or Ap to Vs or Vp, as well as Vp to Vs. In particular, activation intervals may include a pacing (Ap or Vp) to ventricular interval (left ventricular or right ventricular sense) or an atrial-sensing (As) to ventricular-sensing interval (left ventricular or right ventricular).

[0031] Illustrative IMDs may be described as delivering one or both of conventional pacing therapy and cardiac conduction system pacing therapy. Conventional, or traditional, pacing therapy may 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, e.g., the pacing pulses trigger electrical activation that propagates primarily from one myocardial cell to another myocardial cell (also referred to as “cell-to-cell”) as opposed to propagating within the cardiac conduction system prior to the myocardial tissue. For instance, conventional pacing therapy may deliver pacing pulses directly into the muscular heart tissue (e.g., myocardial tissue) that is to be depolarized to provide the contraction of the heart. For example, conventional left ventricular pacing therapy may utilize a left ventricular coronary sinus lead 20 that is implanted so as to extend 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 32of the heart 12 so as to deliver pacing pulses to the myocardial tissue of the free wall of the left ventricle 32.

[0032] An illustrative left ventricular lead 20 with a set of spaced apart electrodes is shown in U.S. Pat. No. 11,278,727, filed on November 20, 2018, by Stegemann et al., which is incorporated by reference in its entirety herein. Illustrative electrodes on leads to form pacing vectors are shown and described in U.S. Pat. No. 8,355,784 B2, and U.S. Pat. No. 8,126,546, each of which are incorporated by reference in their entireties. Illustrative cardiac conduction system pacing therapy may be described in, for example, U.S. Pat. No. 11,207,529 Al entitled “His Bundle and Bundle Branch Pacing Adjustment” issued on December 28, 2021, which is incorporated herein by reference in its entirety. Illustrative left ventricular septal pacing may be described in, for example, U.S. Pat. No. 11,633,607 entitled “AV Synchronous Septal Pacing” issued on April 25, 2023, which is incorporated herein by reference in its entirety.

[0033] One or more elongated conductors of any of the leads 18, 20, 23 may extend through a hermetic feedthrough assembly, and within an insulative tubular member of the respective lead, and may electrically couple an electrical pulse generator (contained within housing) to one or more electrodes such as, e.g., ring electrodes, tips electrodes, helical electrodes, etc. The conductors may be formed by one or more electrically conductive wires comprising, for example, MP35N alloy known to those skilled in the art, in a coiled or cabled configuration, and the insulative tubular member may be any suitable medical grade polymer, for example, polyurethane, silicone rubber, or a blend thereof. According to one or more illustrative embodiments, the flexible lead body may extend a pre-specified length (e.g., about 10 centimeters (cm) to about 20 cm, or about 15 to 20 cm) from a proximal end to a distal end. The lead body may be less than about 7 French (FR) but typically in the range of about 3 FR to 4 FR in size. In one or more embodiments, about 2 FR size to about 3 FR size lead body is employed.

[0034] Cardiac conduction system pacing may include at least one of His bundle pacing and left and / or right bundle branch pacing. Bundle branch pacing may bypass the pathological region and may have a low and stable pacing threshold. In some embodiments, only one of the left bundle branch or the right bundle branch may be paced using one or more pacing leads. In further embodiments, both bundle branches may be paced at the same time (e.g., dual bundle branch pacing), which may mimic intrinsic activation propagation via theHis bundle-Purkinje conduction system, e.g., paced activation propagates via both bundle branches to both ventricles for synchronized contraction. His bundle pacing, on the other hand, typically paces the His bundle proximal to the bundle branches. In some embodiments, the IMD 16 may include one, two, or more electrodes located in one or more bundle branches configured for bundle branch pacing.

[0035] In some embodiments, the IMD 16 may be an intracardiac pacemaker or leadless pacing device (LPD) configured to pace one or more portions of the cardiac conduction system such as the His bundle. As used herein, “leadless” refers to a device being free of a lead extending out of the heart 12. In other words, a leadless device may have a lead that does not extend from outside of the heart to inside of the heart. Some leadless devices may be introduced through a vein, but once implanted, the leadless devices are free of, or may not include, any transvenous lead and may be configured to provide cardiac therapy without using any transvenous lead. In one or more embodiments, an illustrative LPD for bundle pacing does not use a lead to operably connect to an electrode disposed proximate to the septum when a housing of the device is positioned in the atrium. A leadless electrode may be leadlessly coupled to the housing of the medical device without using a lead between the electrode and the housing.

[0036] The IMD 16 may sense electrical signals attendant to the depolarization and repolarization of the heart 12 via various electrodes as shown in FIG. 2B coupled to at least one of leads 18, 20, 23. In some examples, the IMD 16 provides pacing pulses to the heart 12 based on the electrical signals sensed within the heart 12. The configurations of the electrodes used by the IMD 16 for sensing and pacing may be unipolar or bipolar.

[0037] The IMD 16 may also provide defibrillation therapy and / or cardioversion therapy via electrodes located on at least one of the leads 18, 20, 23. For example, the IMD 16 may detect atrial arrhythmias of heart 12, such as atrial fibrillation of the atria 26, 33, and then may deliver defibrillation therapy to the heart 12 in the form of electrical pulses. Also, the IMD 16 may detect ventricular arrhythmias of the heart 12, such as ventricular fibrillation of the ventricles 28, 32, and then may deliver defibrillation therapy to the heart 12 in the form of electrical pulses. In some examples, the IMD 16 may be programmed to deliver a progression of therapies, e.g., pulses with increasing energy levels, until fibrillation of the heart 12 is stopped. The IMD 16 may detect fibrillation employing one or more fibrillation detection techniques known in the art.

[0038] In some examples, the programmer 24 as shown in FIG. 2 A may be a handheld computing device or a computer workstation or a mobile phone. 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 cathode ray tube (CRT) display, a liquid crystal 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. Through the graphical user interface on the programmer 24, a user may configure one or more pacing therapies, select one or more pacing modes, etc.

[0039] Additionally, various pacing settings may be adjusted, or configured, based on various sensed signals. For example, various near-field and far-field signals may be sensed by one or more of the electrodes of the IMD 16 and / or other devices operatively coupled thereto.

[0040] For example, cardiac morphology, such as the morphology of ventricular activation, may be monitored or measured within a near-field or far-field signal and then may be used to adjust, configure, and select cardiac conduction system pacing therapy. More specifically, one or more or a plurality of fiducial points or portions of the ventricular morphology may be measured and compared to a representative, or template, ventricular morphology to determine whether the cardiac conduction system pacing therapy should be adjusted, to determine whether the cardiac conduction system pacing therapy has effectively captured one or both of the left ventricle and right ventricle, and to determine whether the cardiac conduction system pacing therapy has fused with intrinsic ventricular activation resulting in fused beats or ventricular activations. Further, for example, P-wave-to-R-wave interval may be monitored or measured within a near-field or far-field signal and then may be used to adjust, configure, and select cardiac conduction system pacing therapy. Further, for example, QRS width may be monitored or measured within a near-field or far-field signal and then may be used to adjust, configure, and select cardiac conduction system pacing therapy. Still further, for example, one or more of P-wave-to-R-wave interval consistency, T- wave-to-P-wave interval consistency, and P-wave morphology consistency may be monitored or measured within a near-field or far-field signal and then may be used to adjust, configure, and select cardiac conduction system pacing therapy.

[0041] As used herein, the term “far-field” electrical signal refers to the result of measuring cardiac activity using a sensor, such as an electrode, positioned outside of an area of interest. For example, a far-field electrical signal representing electrical activity of a chamber of interest of the patient’s heart may be measured from an electrode positioned in an adjacent chamber (i.e., a chamber different from than that of the chamber of interest that is next to or near the chamber of interest). More specifically, for example, atrial electrical activity, or electrical activity originating one or more both atria, representative of depolarization of the one or both atria may be monitored in a far-field electrical signal measured using an electrode positioned outside of the right atrium such as in the right or left ventricle, or in the ventricular septum. As used herein, the term “near-field” electrical signal refers to the result of measuring cardiac activity using a sensor, such as an electrode, positioned near an area of interest. For example, an electrical signal measured from an electrode positioned on the left side of the patient’s ventricular septum is one example of a near-field electrical signal of the patient’s LV.

[0042] P-wave timing is the time at which a P-wave is detected. Typically, P-wave timing includes using the maximal first derivative of a P-wave upstroke (or the time of the maximal P-wave value). P-wave timing is also used in the device marker channel to indicate the time of the P-wave or the time of atrial activation. P-wave timing may be determined using near- field signals obtained by sensors (e.g., electrodes, accelerometers, heart sound sensors, etc.) positioned in the atria (e.g., the right atrium) and / or far-field near-field signals obtained by sensors (e.g., electrodes, accelerometers, heart sound sensors, etc.) positioned outside of the atria (e.g., the right atrium) such as in the right ventricle and / or ventricular septum.

[0043] R-wave timing is the time at which the QRS complex is detected. Typically, R- wave timing includes using the maximal first derivative of an R-wave upstroke (or the time of the maximal R-wave value). R-wave timing is also used in the device marker channel to indicate the time of the R-wave or the time of ventricular activation.

[0044] A user, such as a physician, technician, or other clinician, may interact with the programmer 24 to communicate with the IMD 16. For example, the user may interact with the programmer 24 to retrieve physiological or diagnostic information from the IMD 16. Additionally, a user may also interact with the programmer 24 to program the IMD 16, e.g., select values for operational parameters of the IMD 16. The IMD 16 and programmer 24 may communicate via wireless communication using any techniques known in the art. Examplesof 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 may be 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.

[0045] FIG. 2B is a conceptual diagram illustrating the IMD 16 and the leads 18, 20, 23 of the therapy system 10 in greater detail. The triple-chamber IMD 16 may be used for cardiac rhythm therapy and defibrillation or cardioversion therapy (CRT-D). The leads 18, 20, 23 may be electrically coupled to a stimulation generator, a sensing module, or other modules of IMD 16 via connector block 34. In some examples, proximal ends of leads 18, 20, 23 may include electrical contacts that electrically couple to respective electrical contacts within the connector block 34. In addition, in some examples, the leads 18, 20, 23 may be mechanically coupled to the connector block 34 with the aid of set screws, connection pins, or another suitable mechanical coupling mechanism.

[0046] Each of the leads 18, 20, 23 includes an elongated, insulative lead body, which may carry any number of concentric coiled conductors separated from one another by tubular, insulative sheaths. In the illustrated example, an optional pressure sensor 38 and bipolar electrodes 40 and 42 are located proximate to a distal end of the right ventricular lead 18. In addition, the bipolar electrodes 44 and 46 are located proximate to a distal end of the left ventricular lead 20 and bipolar electrodes 48 and 50 are located proximate to a distal end of cardiac conduction system pacing lead 23. The cardiac conduction system pacing electrode 50 may be used for pacing and / or sensing of the cardiac conduction system tissue (e.g., His bundle or bundle branch tissue).

[0047] In FIG. 2B, the pressure sensor 38 is disposed in right ventricle 28 and may respond to an absolute pressure inside right ventricle 28. The pressure sensor 38 may be, for example, a capacitive or piezoelectric absolute pressure sensor. In other examples, the pressure sensor 38 may be positioned within other regions of the heart 12 and may monitor pressure within one or more of the other regions of the heart 12, or the pressure sensor 38 may be positioned elsewhere within or proximate to the cardiovascular system of the patient 14 to monitor cardiovascular pressure associated with mechanical contraction of the heart. Optionally, a pressure sensor in the pulmonary artery can be used that is in communication with the IMD 16.

[0048] The electrodes 40, 44 and 48 may take the form of ring electrodes, and the electrodes 42, 46 and 50 may take the form of extendable and / or fixed helix tip electrodes mounted within the insulative electrode heads 52, 54 and 56, respectively. In particular, the cardiac conduction system pacing electrode 50 may take the form of a helix (also referred to as a helical electrode) that may be positioned proximate to, near, adjacent to, or in, area or portions of the cardiac conduction system such as, e.g., ventricular septum, triangle of Koch, the His bundle, left right bundle branch tissues, and / or right bundle branch tissue. The cardiac conduction system pacing lead 23 may be configured as a bipolar lead or as a quadripolar lead that may be used with a pacemaker device, a CRT-P device or a CRT-ICD. Each of the electrodes 40, 42, 44, 46, 48 and 50 may be electrically coupled to a respective one of the coiled conductors within the lead body of its associated lead 18, 20, 23, and thereby coupled to respective ones of the electrical contacts on the proximal end of the leads 18, 20 23.

[0049] The electrodes 40, 42, 44, 46, 48 and 50 may sense electrical signals 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, 23. In some examples, the IMD 16 also delivers pacing pulses via the electrodes 40, 42, 44, 46, 48, 50 to cause depolarization of cardiac tissue of heart 12. In some examples, as illustrated in FIG. 2B, the IMD 16 may include one or more housing electrodes, such as housing electrode 58, which may be formed integrally with an outer surface of a hermetically sealed housing 60 of the IMD 16 or otherwise coupled to the housing 60. In some examples, the housing electrode 58 may be defined by an uninsulated portion of an outward facing portion of the housing 60 of the IMD 16. Other divisions between insulated and uninsulated portions of housing 60 may be employed to define two or more housing electrodes. In some examples, the housing electrode 58 includes substantially all of the housing 60. Any of the electrodes 40, 42, 44, 46, 48, 50 may be used for unipolar sensing or pacing in combination with the housing electrode 58 or for bipolar sensing with two electrodes in the same pacing lead. In one or more embodiments, the housing 60 may enclose a stimulation generator (see FIG. 5) that generates cardiac pacing pulses and defibrillation or cardioversion shocks, as well as a sensing module for monitoring the patient’s heart rhythm.

[0050] The leads 18, 20, 23 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 cardioversionpulses to the heart 12. The electrodes 62, 64, 66 may be fabricated from any suitable electrically conductive material, such as, but not limited to, platinum, platinum alloy or other materials known to be usable in implantable defibrillation electrodes.

[0051] The pressure sensor 38 may be coupled to one or more coiled conductors within the lead 18. In FIG. 2B, the pressure sensor 38 is located more distally on the lead 18 than elongated electrode 62. In other examples, the pressure sensor 38 may be positioned more proximally than the elongated electrode 62, rather than distal to the electrode 62. Further, the pressure sensor 38 may be coupled to another one of the leads 20, 23 in other examples, or to a lead other than the leads 18, 20, 23 carrying stimulation and sense electrodes. In addition, in some examples, the pressure sensor 38 may be self-contained device that is implanted within the heart 12, such as within the ventricular septum separating the right ventricle 28 from the left ventricle 32, or the atrial septum separating the right atrium 26 from the left atrium 33. In such an example, the pressure sensor 38 may wirelessly communicate with the IMD 16.

[0052] Although FIGS. 2A-2B depict a three-chamber therapy system 10, it is to be understood that other systems configured to delivery therapy to less than three chambers, such as a dual-chamber therapy system or a single-chamber therapy system, may be configured to utilize the cardiac conduction system pacing therapy adjustment methods, processes, and algorithms described further herein. For example, an illustrative dual-chamber therapy system may include only leads 18, 23, of system 10. The leads 18, 23 may be implanted within the right ventricle 28 and the right atrium 26 to pace one or more portions of the cardiac conduction system such as the His bundle or one or both bundle branches, respectively. Further, for example, an illustrative single-chamber therapy system may include only lead 23 of system 10. The lead 23 may be implanted the right atrium 26 to pace one or more portions of the cardiac conduction system such as the His bundle or one or both bundle branches, respectively.

[0053] FIGS. 3A-3B show the patient’s heart 12 implanted with an implantable medical electrical lead 123 coupled to an IMD 116 to deliver bundle branch pacing according to one example of an IMD system 110. FIG. 3B is a close-up view of lead 123 in the patient’s heart 12 of FIG. 3 A. In some embodiments, the electrical lead 123 may be the only lead implanted in the heart 12. 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 pacingelectrode implantable proximate the cardiac conduction system or may be implantable in the ventricular septum (VS), to deliver cardiac conduction system pacing therapy, for examples.

[0054] In one embodiment, the lead 123 may be configured for dual bundle branch pacing, and the lead 123 may be the same as or similar to the lead 23 shown in FIGS. 2A-2B except that the lead 123 of system 110 of FIGS. 3A-3B is implanted near the bundle branches in the ventricular septum (VS) from the right ventricle 28 instead of, for example, the His bundle 13. As illustrated, the lead 123 is implanted in the septal wall, or ventricular septum, from the right ventricle 28 toward the left ventricle 32. In one embodiment, the lead 123 may not pierce through the wall of the left ventricle 32 or extend into the left ventricular chamber. In one embodiment, the lead 123 may pierce through the wall of the left ventricle 32 and extend into the left ventricular chamber a short distance. An electrode 152 and a tissue-piercing electrode 150 may be disposed on a distal end portion of the lead 123, which may also be described as a shaft. The electrode 152 and the tissue-piercing electrode 150 may be the same as or similar to electrode and tissue-piercing electrode 50 shown in FIG. 2B except that the electrode 152 is configured as a cathode electrode to sense or pace the right bundle branch and the electrode 150 is configured as a cathode electrode to sense or pace the left bundle branch, for example, during dual bundle branch pacing. Accordingly, the electrode 152 may be implanted near right bundle branch 8b, and the electrode 150 may be implanted near the left bundle branch 8a. In other words, the electrode 150 may be described as a unipolar cathode electrode, which may be implanted on the left side of the patient’s ventricular septum, and the electrode 152 may be described as a unipolar cathode electrode, which may be implanted on the right side of the patient’s ventricular septum.

[0055] During dual bundle branch pacing, both the electrode 152 and the electrode 150 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.

[0056] Although the lead 123 as shown in configured for dual bundle branch pacing using the electrodes 150, 152, it is to be understood that the lead 123 or leads similar thereto are considered herein that may only include one of the electrode 150 and the electrode 152,and thus, only configured to deliver cardiac conduction system pacing therapy to one of the left bundle branch and the right bundle branch.

[0057] Additionally, the lead 123 may include a right atrial electrode 170 disposed more proximal to the electrodes 150, 152 along the lead 123. The right atrial electrode 170 may be positioned in or near the right atrium 26 and may function as an anode for cathodal pulses from the electrode 150 and / or the electrode 152. Further, the right atrial electrode 170 may provide atrial sensing to, e.g., sense atrial depolarizations or activations, to sense or detect atrial fibrillation, etc. Although the lead 123 as shown includes the right atrial electrode 170, it is to be understood that the lead 123 may not include the right atrial electrode 170, and instead, only include one or both of the electrode 150 and the electrode 152.

[0058] Still further, the system 110 may include a mechanical cardiac activation sensor 151 coupled to the lead 123 as shown in FIG. 3B. As shown, when the distal end of the lead 123 is implanted through the right ventricle 28 into the ventricular septum, the mechanical cardiac activation sensor 151 may be positioned in the right ventricle 28. The mechanical cardiac activation sensor 151 may be a motion sensor (e.g., an accelerometer) and / or a heart sound sensor (e.g., a microphone) that may be used to determined atrial activation or depolarization (e.g., atrial kick) so as to be used to deliver atrioventricular timed cardiac conduction system pacing therapy. In other words, the system 110 may be configured to monitor mechanical activity of the patient’s heart using the mechanical cardiac activation sensor, determine atrial activation based on the monitored mechanical activity, and deliver cardiac conduction system pacing using the cardiac conduction system pacing electrode based on the determined atrial activation. Additionally, in one or more embodiments, the mechanical cardiac activation sensor 151 may be located in a housing of the IMD 116, which not be located within the heart of the patient. For example, the house of the IMD 116 may be positioned subcutaneously with the body of the patient. Furthermore, if the system 110 includes a leadless device, the mechanical cardiac activation sensor 151 may be located in a housing of the leadless device implanted in the right ventricle 28.

[0059] Furthermore, atrial activations determined using the mechanical cardiac activation sensor 151 may be used in conjunction with atrial activations determined using near-field or far-field electrical activity. In at least one embodiment, the atrial activations determined using the mechanical cardiac activation sensor 151 may be used to confirm atrial activations determined using near-field or far-field electrical activity, or vice versa.

[0060] FIG. 4 is a conceptual diagram of an illustrative 210 including an IMD, or pacemaker, 216 configured as a multi-chamber pacemaker, a right atrial pacing and sensing lead 219 and a cardiac conduction system pacing lead 223 configured for delivering bundle branch pacing. The IMD 216 includes a housing 215 and is coupled to the right atrial lead 219 carrying a pacing tip electrode 236 and a proximal ring electrode 238 that may be used for sensing right atrial signals and delivering atrial pacing to the right atrium, and to the cardiac conduction system pacing lead 232 carrying a pacing tip electrode 250 and a proximal ring electrode 252 that may be used for sensing ventricular signals and delivering cardiac conduction system pacing to one or both bundle branches of the cardiac conduction system. The cardiac conduction system pacing lead 232 may further include, or carry, a coil electrode 235 for delivering unipolar right atrial pacing and / or sensing and delivering high voltage cardioversion / defibrillation shock therapies for cardioverting or defibrillating the heart in response to detecting a ventricular tachyarrhythmia. The coil electrode 235 may be selected in a unipolar pacing electrode vector with any of electrodes 250, 252, 236, 238

[0061] The configuration of therapy systems 10, 110, 210 illustrated in FIGS. 2-4 are merely examples. In other examples, therapy systems may include epicardial leads and / or patch electrodes instead of or in addition to the transvenous leads illustrated in FIGS. 2-4 or other configurations shown or described herein or incorporated by reference. Further, the IMDs 16, 116, 216 need not be implanted within patient 14. As such, it is to be understood that the illustrative therapy systems described herein may include any suitable number of leads coupled to IMDs 16, 116, 216 and each of the leads may extend to any location within or proximate to the heart 12. For example, illustrative therapy systems may include three transvenous leads as illustrated in FIGS. 2A-2B, a single transvenous lead as illustrated in FIGS. 3 A-3B, or two transvenous leads as illustrated in FIG. 4.

[0062] FIG. 5 is a functional block diagram of one example configuration of the IMD 16. Although the IMD 16 of FIG. 5 is described in terms of the systems shown in FIGS. 2A-2B, it is to be understood that the IMDs 116, 216 may be substantially similar to the IMD 16, and as such, the IMDs 116, 216 may include any or all of the described functionality with respect to the functional block diagram of IMD 16.

[0063] The IMD 16 includes a processor 80, a memory 82, a stimulation generator 84 (e.g., electrical pulse generator or signal generating circuit), a sensing module 86 (e.g., sensing circuit), a telemetry module 88, and a power source 90. One or more components ofthe IMD 16, such as the processor 80, may be contained within a housing of the IMD 16 (e.g., within a housing of a pacemaker). The telemetry module 88, the sensing module 86, or both the telemetry module 88 and the sensing module 86 may be included in a communication interface. The memory 82 includes computer-readable instructions that, when executed by the processor 80, cause the IMD 16 and the processor 80 to perform various functions attributed to the IMD 16 and the processor 80 herein. The memory 82 may include any volatile, non-volatile, magnetic, optical, 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, or any other digital media.

[0064] The processor 80 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), or equivalent discrete or integrated logic circuitry. In some examples, processor 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, or one or more FPGAs, as well as other discrete or integrated logic circuitry. The functions attributed to processor 80 herein may be embodied as software, firmware, hardware or any combination thereof. The processor 80 controls the stimulation generator 84 to provide and / or adjust, for example, cardiac conduction system pacing therapy according to illustrative methods, processes, algorithms, variables, and data which may be stored in the memory 82 and based on various sensing (e.g., cardiac morphology, ventricular morphology, QRS complex morphology, atrial depolarizations or activations, ventricular atrial depolarizations or activations, heartrate, P-wave-to-R-wave intervals, etc.). Specifically, the processor 80 may control the stimulation generator 84 to deliver electrical pulses with amplitudes, pulse widths, frequency, or electrode polarities according to various timings (e.g., atrioventricular delays).

[0065] The stimulation generator 84 may be electrically coupled to the electrodes 40, 42, 44, 46, 48, 50, 58, 62, 64, and 66, e.g., via conductors of the respective lead 18, 20, 23 or, in the case of housing electrode 58, via an electrical conductor disposed within the housing 60 of the IMD 16. The stimulation generator 84 may be configured to generate and deliver electrical stimulation therapy to the heart 12. For example, the stimulation generator 84 may deliver defibrillation shocks to the heart 12 via at least two of the electrodes 58, 62, 64, 66. The stimulation generator 84 may deliver pacing pulses via the ring electrodes 40, 44, 48 coupled to the leads 18, 20, 23, respectively, and / or the helical electrodes 42, 46, 50 of theleads 18, 20, or 23, respectively. The cardiac conduction system pacing therapy can be delivered through the cardiac conduction system lead 23 that is connected to an atrial, right ventricular, or left ventricular connection port of the connector block 34. In some embodiments, the cardiac conduction system pacing therapy can be delivered through the leads 18 and / or 23. In some examples, the stimulation generator 84 delivers pacing, cardioversion, or defibrillation stimulation in the form of electrical pulses. In other examples, the stimulation generator 84 may deliver one or more of these types of stimulation in the form of other signals, such as sine waves, square waves, or other substantially continuous time signals.

[0066] The stimulation generator 84 may include a switch module and the processor 80 may use the switch module to select, e.g., via a data / address bus, which of the available electrodes are used to deliver defibrillation shocks or pacing pulses. The switch module may include a switch array, switch matrix, multiplexer, or any other type of switching device suitable to selectively couple stimulation energy to selected electrodes.

[0067] The sensing module 86 monitors signals from at least one of the electrodes 40, 42, 44, 46, 48, 50, 58, 62, 64 or 66 in order to monitor electrical activity of the heart 12, e.g., via electrical signals, such as electrocardiogram (ECG) signals and / or electrograms (EGMs). The electrical signals may provide cardiac morphology, which may be analyzed to determine whether the cardiac conduction system pacing therapy is effective, to determine to adjust the cardiac conduction system pacing therapy, to determine whether the cardiac conduction system pacing therapy has captured one or both of the right ventricle and right ventricle, and to determine whether the cardiac conduction system pacing therapy has fused with intrinsic ventricular activation. The sensing module 86 may also include a switch module to select which of the available electrodes are used to sense the heart activity. In some examples, the processor 80 may select the electrodes that function as sense electrodes via the switch module within the sensing module 86, e.g., by providing signals via a data / address bus. In some examples, the sensing module 86 includes one or more sensing channels, each of which may include an amplifier. In response to the signals from the processor 80, the switch module may couple the outputs from the selected electrodes to one of the sensing channels.

[0068] In some examples, one channel of the sensing module 86 may include an R-wave amplifier that receives signals from the electrodes 44, 46, which are used for pacing and sensing proximate to the left ventricle 32 of the heart 12. Another channel may includeanother R-wave amplifier that receives signals from the electrodes 40, 42, which are used for pacing and sensing in the right ventricle 28 of the heart 12. In some examples, the R-wave amplifiers may take the form of an automatic gain-controlled amplifier that provides an adjustable sensing threshold as a function of the measured R-wave amplitude of the heart rhythm.

[0069] In addition, in some examples, one channel of the sensing module 86 may include a P-wave amplifier that receives signals from electrodes the 48, 50, which are used for pacing and sensing in the right atrium 26 of heart 12. In some examples, the P-wave amplifier may take the form of an automatic gain-controlled amplifier that provides an adjustable sensing threshold as a function of the measured P-wave amplitude of the heart rhythm. Examples of R-wave and P-wave amplifiers are described in U.S. Patent No. 5,117,824 to Keimel et al., which issued on June 2, 1992, and is entitled, “APPARATUS FOR MONITORING ELECTRICAL PHYSIOLOGIC SIGNALS,” and is incorporated herein by reference in its entirety. Other amplifiers may also be used. Furthermore, in some examples, one or more of the sensing channels of the sensing module 86 may be selectively coupled to the housing electrode 58, or the elongated electrodes 62, 64, or 66, with or instead of one or more of the electrodes 40, 42, 44, 46, 48 or 50, e.g., for unipolar sensing of R-waves or P-waves in any of the chambers 26, 28, or 32 of the heart 12.

[0070] In some examples, the sensing module 86 includes a channel that includes an amplifier with a relatively wider pass band than the R-wave or P-wave amplifiers or a high- resolution amplifier with relatively narrow-pass band for His bundle or bundle branch potential recording. Signals from the selected sensing electrodes that are selected for coupling to this wide-band amplifier may be provided to a multiplexer, and thereafter converted to multi-bit digital signals by an analog-to-digital converter for storage in the memory 82 as an electrogram (EGM). In some examples, the storage of such EGMs in the memory 82 may be under the control of a direct memory access circuit. The processor 80 may employ digital signal analysis techniques to characterize the digitized signals stored in memory 82 to detect and classify the patient’s heart rhythm from the electrical signals. The processor 80 may detect and classify the heart rhythm of the patient 14 by employing any of the numerous signal processing methodologies known in the art.

[0071] If the IMD 16 is configured to generate and deliver pacing pulses to the heart 12, the processor 80 may include pacer timing and control module, which may be embodied ashardware, firmware, software, or any combination thereof. The pacer timing and control module may include a dedicated hardware circuit, such as an ASIC, separate from other the processor 80 components, such as a microprocessor, or a software module executed by a component of the processor 80, which may be a microprocessor or ASIC. The pacer timing and control module may include programmable counters which control the basic time intervals associated with DDD, VVI, DVI, VDD, AAI, DDI, DDDR, VVIR, DVIR, VDDR, AAIR, DDIR and other modes of single and dual chamber pacing. In the aforementioned pacing modes, “D” may indicate dual chamber, “V” may indicate a ventricle, “I” may indicate inhibited pacing (e.g., no pacing), and “A” may indicate an atrium. The first letter in the pacing mode may indicate the chamber that is paced, the second letter may indicate the chamber in which an electrical signal is sensed, and the third letter may indicate the chamber in which the response to sensing is provided.

[0072] Intervals defined by the pacer timing and control module may include atrial and ventricular pacing escape intervals, refractory periods during which sensed P-waves and R- waves are ineffective to restart timing of the escape intervals, and the pulse widths of the pacing pulses. As another example, the pace timing and control module may define a blanking time period and provide signals from sensing module 86 to blank one or more channels, e.g., amplifiers, for a period during and after delivery of electrical stimulation to the heart 12. The durations of these intervals may be determined by the processor 80 in response to stored data in the memory 82. The pacer timing and control module may also determine the amplitude of the cardiac pacing pulses.

[0073] During pacing, escape interval counters within the pacer timing / control module may be reset upon sensing of R- waves and P-waves. The stimulation generator 84 may include pacer output circuits that are coupled, e.g., selectively by a switching module, to any combination of the electrodes 40, 42, 44, 46, 48, 50, 58, 62, or 66 appropriate for delivery of a bipolar or unipolar pacing pulse to one of the chambers of the heart 12. The processor 80 may reset the escape interval counters upon the generation of pacing pulses by stimulation generator 84, and thereby control the basic timing of cardiac pacing functions, including antitachyarrhythmia pacing.

[0074] Additionally, sensing module 86 and the processor 80 may utilize, or use, one or more methods, processes, algorithms, or techniques to determine effectiveness of cardiac conduction system pacing therapy. The one or more methods, processes, algorithms, ortechniques may include determining effective capture of the cardiac conduction system over one or more cardiac cycles (or heart beats) using cardiac morphology monitored using one or more signals (e.g., measured using at least an electrode located in the right ventricle). For example, a percentage of cardiac cycles where the cardiac conduction system has been effectively captured may be determined and monitored. In one or more embodiments, the illustrative systems, devices, and methods may use, or utilize, the EffectivCRT™ algorithm, available from Medtronic pic of Dublin, Ireland, or similar process to determine effective cardiac conduction system pacing therapy, e.g., based on the morphology of resulting cardiac electrical activity in a particular observation vector, such as from a tip cardiac conduction system pacing electrode to a right-ventricular pacing cathode. An example of EffectivCRT™ is described in U.S. Patent No. 8,750,998 to Ghosh et al, which is entitled “EFFECTIVE CAPTURE TEST,” and issued on June 10, 2014, which is incorporated herein by reference in its entirety. Another example of use of the EffectivCRT™ algorithm to maintain effective CRT during atrial fibrillation is described in U.S. Patent No. 10,213,606 to Lu et al., which is entitled “MODULATE PACING RATE TO INCREASE THE PERCENTAGE OF EFFECTIVE VENTRICULAR CAPTURE DURING ATRIAL FIBRILLATION,” and issued on February 26, 2019, which is incorporated herein by reference in its entirety.

[0075] In some examples, the processor 80 may operate as an interrupt driven device and is responsive to interrupts from pacer timing and control module, where the interrupts may correspond to the occurrences of sensed P-waves and R-waves and the generation of cardiac pacing pulses. Any necessary mathematical calculations to be performed by the processor 80 and any updating of the values or intervals controlled by the pacer timing and control module of the processor 80 may take place following such interrupts. A portion of the memory 82 may be configured as a plurality of recirculating buffers, capable of holding series of measured intervals, which may be analyzed by the processor 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.

[0076] The telemetry module 88 includes any suitable hardware, firmware, software or any combination thereof for communicating with another device, such as the programmer 24. Under the control of the processor 80, the telemetry module 88 may receive downlink telemetry from and send uplink telemetry to the programmer 24 with the aid of an antenna, which may be internal and / or external. The processor 80 may provide the data to be uplinked to the programmer 24 and the control signals for the telemetry circuit within the telemetrymodule 88, e.g., via an address / data bus. In some examples, the telemetry module 88 may provide received data to the processor 80 via a multiplexer.

[0077] The various components of the IMD 16 are coupled to the 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.

[0078] The illustrative systems, devices, and methods described herein may provide adjustment of cardiac conduction system pacing therapy to result in a more effective cardiac conduction system pacing therapy for positive patient outcomes. More specifically, the illustrative systems, devices, and methods may be described as providing dynamic adjustment of one or more parameters, such as pacing vector including pacing polarity, and paced and sensed AV delays, to ensure effective conduction system pacing using morphology as criteria for successful cardiac conduction system capture (e.g., His bundle capture, left bundle branch capture, right bundle branch capture, etc.).

[0079] An illustrative method 300 of dynamic adjustment of cardiac conduction system pacing therapy and delivery of such cardiac conduction system pacing therapy that may be utilized by the devices of FIGS. 2-5 is depicted in FIG. 6. As shown the method 300 may include delivering cardiac conduction system pacing therapy 302 and monitoring electrical activity 304. In particular, the method 300 may be performed by an IMD using one or more implantable electrodes to deliver cardiac conduction system pacing therapy to the patient’s heart 302 and to sense electrical activity from the patient’s heart 304. Although delivering cardiac conduction system pacing therapy 302 and monitoring electrical activity 304 are shown as separate, consecutive processes in FIG. 6, it is to be understood that both delivering cardiac conduction system pacing therapy 302 and monitoring electrical activity 304 may occur simultaneously and continuously.

[0080] The cardiac conduction system pacing therapy 302 may include delivering pacing pulses to one or more portions of the patient’s cardiac conduction system such as, e.g., the left bundle branch, the right bundle branch, and the bundle of His, using one or more implantable electrodes as described herein with respect to the systems and devices of FIGS. 1-5. For example, the cardiac conduction system pacing therapy 302 may be delivered to the left bundle branch via tip or helix electrode implanted or positioned proximate the left bundle branch within the ventricular septum.

[0081] Further, it is to be understood that the cardiac conduction system pacing therapy may be delivered to the cardiac conduction system using a particular pacing vector. The pacing vector may include (e.g., be formed of) at least two electrodes: at least one of which is the cathode; and at least one of which is the cathode. In one embodiment, a tip or helix electrode implanted or positioned proximate the left bundle branch the ventricular septum may be cathode and another electrode (e.g., a ring electrode) implanted or positioned in the right ventricle (e.g., located in the blood pool of the right ventricle, adjacent the right ventricular septal wall, etc.) may be the anode. The pacing vector may be adjusted, as will be further described herein, to switch polarities or add or subtract an electrode from the pacing vector. More specifically, when switching polarity, the electrode that is operating as the anode may be switched to operate as the cathode, and conversely, the electrode that is operating as the cathode may be switched to operate as the anode. Further, more specifically, when adding an electrode to a pacing vector, an additional electrode may be operated as another cathode in conjunction with an already configured, or used, cathodal electrode and / or an additional electrode may be operated as another anode in conjunction with an already configured, or used, anodal electrode. In this way, a plurality of different pacing vectors may be configured, and each different pacing vector will have, or include, at least one difference than the other different pacing vectors (e.g., one electrode may have a different polarity, a different set of electrodes may be used, etc.).

[0082] The pacing pulses may be delivered periodically and timed accordingly with respect to an atrial sense such as an atrial pace or an intrinsic atrial activation. In particular, the cardiac conduction system pacing may be delivered based on an atrioventricular (AV) delay. The AV delay is the time period between an atrial event, such as an atrial pace or an intrinsic atrial activation, and delivery of a cardiac conduction system pace to the cardiac conduction system. Additionally, the cardiac conduction system pacing therapy may be delivered in accordance with a pacing mode, such as non-inhibited or inhibited mode.

[0083] During the delivery of the cardiac conduction system pacing therapy 302, cardiac electrical activity may be monitored using one or more of plurality of implantable electrodes. For example, cardiac electrical activity may be monitored use an observation vector, such as from a tip cardiac conduction system pacing electrode positioned proximate the left bundle branch to a right-ventricular electrode. The electrical activity may be described as electrocardiogram (ECG) signals and / or electrograms (EGMs). In particular, the cardiac electrical activity immediately following the delivery of a cardiac conduction system pacingpulse being delivered to the cardiac conduction system may be monitored and recorded, or saved, for analysis of the cardiac conduction system pacing therapy. In one or more embodiments, only a portion of the electrical activity following a cardiac conduction system pacing pulse may be monitored. For example, about 50 milliseconds (ms) and 350 ms of electrical activity may be monitored, or measured, following a cardiac conduction system pacing pulse. In one embodiment, the electrical activity may be monitored, or measured, for 150 ms following a cardiac conduction system pacing pulse.

[0084] The cardiac morphology may then be determined 306 based on the monitored cardiac electrical activity. In one or more embodiments, the cardiac morphology may be the ventricular cardiac morphology, which is the morphology of the cardiac electrical activity representative of the electrical activation of one or both of the ventricles. For example, the Il- wave or the QRS complex of the monitored electrical activity may be determined based on the monitored cardiac electrical activity. Each of the R-wave and QRS complex is representative of the electrical activation of one or both of the ventricles.

[0085] The method 300 further includes adjustment of the cardiac conduction system pacing therapy 308 based on the determined cardiac morphology. More specifically, the cardiac morphology may be used to adjust one or more parameters of the cardiac conduction system pacing therapy to provide, if desired, more effective cardiac conduction system pacing therapy. One illustrative adjustment of cardiac conduction system pacing therapy based cardiac morphology is described further herein with respect to FIG. 7. After adjusting the cardiac conduction system pacing therapy 308, the method 300 continues delivering cardiac conduction system pacing therapy 302 in accordance with any adjustments made, monitoring cardiac electrical activity, 304, and determining cardiac morphology 306 such that the method 300 may continuously dynamically adjust the cardiac conduction system pacing therapy.

[0086] An illustrative adjustment 308 of cardiac conduction system pacing therapy is shown in FIG. 7. As shown, the cardiac morphology may be compared 310 to a representative, or template, cardiac morphology and then used to determine whether the cardiac conduction system pacing therapy is effective 312 (e.g., whether the cardiac conduction system pacing therapy has effectively captured the cardiac conduction system, whether the cardiac conduction system pacing therapy is not fusing with intrinsic ventricular activation, whether the cardiac conduction system pacing therapy results in better strokevolume, whether the cardiac conduction system pacing therapy results in more or better synchronized electrical activation and mechanical contraction, etc.). The representative, or template, cardiac morphology may represent, or be representative of, ventricular activation that is effectively initiated, or triggered, via the cardiac conduction system by the cardiac conduction system pacing therapy. The representative, or template, cardiac morphology may not represent, or not be representative of, an ineffective cardiac conduction system pacing therapy. Moreover, the representative, or template, cardiac morphology may not represent, or not be representative of, a cardiac conduction system pacing therapy that has fused with intrinsic ventricular activation resulting in fusion or cardiac conduction system pacing therapy has not captured the cardiac conduction system.

[0087] For example, one or more fiducial points, features, or metrics derived therefrom of the cardiac morphology may be compared to one or more fiducial points, features, or metrics of the representative cardiac morphology to determine whether the cardiac conduction system pacing therapy is effective 312 (e.g., effectively captured the cardiac conduction system). For instance, one or more fiducial points, features, or metrics of the morphologies may include a maximum amplitude, a minimum amplitude, a ratio between the maximum amplitude and minimum amplitude, positive deflection timing with respect to negative deflection timing, and negative deflection timing with respect to positive deflection timing.

[0088] In one embodiment, to determine whether the cardiac conduction system pacing therapy effective (e.g., effectively captures the cardiac conduction system, effectively stimulates synchronous activation the left ventricle, etc.), one or more of the maximum amplitude (Max), the maximum time (Tmax) associated with the maximum amplitude (Max), the minimum amplitude (Min), and the minimum time (Tmin) associated with the minimum amplitude of the cardiac morphology may be utilized. For example, cardiac conduction system pacing therapy may be determined to be effective if one or more of the following is true:Tmax - Tmin > 30 ms;0.2 < |Max - baseline value (BL) | / \BL - Min| < 5; (|Max- Z| / |Min- Z| = and BL < |Min / 8|); Tmin < 60 ms; and Max - Min > 3.5 mVwherein the baseline data value (BL), used as a reference value, is sensed immediately before a pacing stimulus is delivered, and the lower limit (LL) and upper limit (UL) are associated with upper and lower ratio limits, respectively, of a morphological feature. Exemplary LL can be 0.2 with a range of 0.1 to 0.33 and exemplary UL can be 5.0 with a range of 3.0 to 10.0. Preferably, LL is set at 0.125 and the UL is set at 8.0.

[0089] For example, if Tmax-Tmin is greater than 30 ms, then the cardiac conduction system pacing therapy may be determined to be effective, and conversely if Tmax-Tmin is less than or equal to 30 ms, then the cardiac conduction system pacing therapy may be determined to be ineffective. Further, for example, if Tmin is less than 60 ms, then the cardiac conduction system pacing therapy may be determined to be effective, and conversely if Tmin is greater than or equal to 60 ms, then the cardiac conduction system pacing therapy may be determined to be ineffective.

[0090] In one or embodiments, the comparison may provide an effectiveness score. The effectiveness score may then be compared to a threshold capture score determine effective cardiac conduction system pacing therapy. For example, if the effectiveness score is greater than or equal to the threshold capture score, then it may indicate effective cardiac conduction system pacing therapy, and conversely, if the effectiveness score is less than to the threshold capture score, then it may indicate ineffective cardiac conduction system pacing therapy.

[0091] If effective cardiac conduction system pacing therapy is determined 312, then method may return to delivering cardiac conduction system pacing therapy and monitoring electrical activity without any adjustment. If effective cardiac conduction system pacing therapy is not determined 312, one or both of cardiac conduction system pacing therapy vector adjustment 320 and AV delay adjustment 322 may be performed in an attempt to achieve effective cardiac conduction system pacing therapy.

[0092] For example, as described herein, the cardiac conduction system pacing therapy may be delivered using a particular pacing vector such as, for instance, a cardiac conduction system pacing therapy electrode positioned proximate a portion of the cardiac conduction system may be utilized as a cathode and another implanted electrode may be used as an anode. In one embodiment, such as shown in FIGS. 2A-2B, the cardiac conduction system pacing therapy electrode 50 may be used as the cathode and the electrode 48 may be used as the anode. In one embodiment, such as shown in FIGS. 3 A-3B, the cardiac conductionsystem pacing therapy electrode 150 may be used as the cathode and the electrode 170 may be used as the anode. In one embodiment, such as shown in FIG. 4, the cardiac conduction system pacing therapy electrode 250 may be used as the cathode and the electrode 252 may be used as the anode.

[0093] If effective cardiac conduction system pacing therapy is not determined, the present cardiac conduction system pacing therapy vector may be changed 320. For example, the polarity of the anode and cathode of the pacing vector may be switched. More specifically, in the example, with respect to FIG. 4, cardiac conduction system pacing therapy electrode 250 may switched to be configured, or used, as the anode and the electrode 252 may be switched to be configured, or used, as the cathode. In this way, the cardiac conduction system pacing therapy vector may be modified, or adjusted, by switching the polarity of one or more electrodes of the cardiac conduction system pacing therapy vector.

[0094] Further, for example, one or more electrodes may be added to and subtracted from the cardiac conduction system pacing therapy vector. More specifically, in the example, with respect to FIGS. 2A-2B, the housing electrode 58 may replace the electrode 48 as the anode in the cardiac conduction system pacing therapy vector. In this way, the cardiac conduction system pacing therapy vector may be modified, or adjusted, by switching which electrode acts as the anode.

[0095] Further, for example, one or more electrodes may be added to the cardiac conduction system pacing therapy vector. More specifically, in the example, with respect to FIGS. 2A-2B, the housing electrode 58 may be used in addition to the electrode 48 as a multielectrode anode in the cardiac conduction system pacing therapy vector. In this way, the cardiac conduction system pacing therapy vector may be modified, or adjusted, by adding anodal electrodes. It is to be understood, however, that any change to the cardiac conduction system pacing therapy vector is contemplated by the present disclosure.

[0096] One factor leading to fused beats is a delay in right atrial sensing by the right atrial lead. When the sinoatrial (SA) node depolarizes, the impulse travels through the atrium. It is then sensed by the right atrial pacing lead. The signal sensed by the atrial lead begins the programmed sensed atrioventricular (AV) delay before cardiac conduction system ventricular pacing. However, a significant delay may occur between SA nodal depolarization and right atrial lead sensing, which has been described as right atrial sensing latency (RASL). Whenlatency occurs, the atrial activation wavefront reaches the AV nodal area at or near the same time as ventricular pacing, thus, resulting is fusion.

[0097] As noted herein, if effective cardiac conduction system pacing therapy is not determined 312, AV delay adjustment 322 may be performed in an attempt to achieve effective cardiac conduction system pacing therapy. For example, the AV delay at which the cardiac conduction system pacing therapy is being delivered may be adjusted 322 (e.g., increased or decreased) in response to effective cardiac conduction system pacing therapy being not determined 312. In one embodiment, the AV delay may be decreased by an AV adjustment value or AV adjustment percentage. The AV adjustment value may be between about 5 milliseconds (ms) and about 50 ms. In one embodiment, the AV adjustment value is 20 ms. Thus, if the AV delay was 220 ms, the AV adjustment value is 20 ms, and effective cardiac conduction system pacing therapy was not determined 312, the AV delay may be decreased by 20 ms resulting in an AV delay of 200 ms. Further, the AV adjustment percentage may be between about 2.5 % and about 15%. In one embodiment, the AV adjustment percentage is 5%. Thus, if the AV delay was 240 ms, the AV adjustment percentage is 10 %, and effective cardiac conduction system pacing therapy was not determined 312, the AV delay may be decreased by 24 ms (i.e., 20% of 240 ms) resulting in an AV delay of 216 ms.

[0098] As noted herein, one or both of the cardiac conduction system pacing therapy vector 320 and the AV delay 322 may be adjusted. For example, in one embodiment, the cardiac conduction system pacing therapy vector 320 is adjusted and the AV delay is not to be adjusted. Further, for example, in one embodiment, the AV delay is adjusted 322 and the conduction system pacing therapy vector 320 is not adjusted. Still further, for example, in one embodiment, the AV delay is adjusted 322 and the conduction system pacing therapy vector 320 is adjusted. After each adjustment, the cardiac conduction system pacing therapy may be delivered, electrical activity monitored, cardiac morphology determined, and it may again be determined whether or not to adjust the cardiac conduction system pacing therapy again as shown in method 300. This cycle may continue until all adjustments are exhausted or the adjustments succeed to achieving effective cardiac conduction system pacing therapy.

[0099] Another illustrative adjustment 308 of cardiac conduction system pacing therapy of FIG. 6 is depicted in FIG. 8. The adjustment processes 308 may be generally described as comparing the determined cardiac morphology based on monitored electrical activity to aLBB capture morphology, and adjusting AV delay until the determined cardiac morphology is substantively equivalent to the LBB capture morphology. The LBB capture morphology may be described as template morphology that is indicative of LBB capture. In some examples, the LBB capture morphology may be similar to R-prime morphology but monitorable using electrical activity monitored using implanted electrodes (e.g., intracardiac electrograms).

[0100] More specifically, initially, the cardiac morphology monitored while delivery of cardiac conduction system pacing therapy using a bipolar pacing vector is compared to the LBB capture morphology 342. The bipolar pacing vector may include a cardiac conduction system pacing therapy pacing electrode positioned proximate the left bundle branch being configured as the cathode and a right ventricular electrode positioned in or proximate to the right ventricle being configured as the anode. If the cardiac morphology substantively matches, or is substantively equivalent to, the LBB capture morphology within, for example, a selected tolerance, then the method 300 may continue delivering cardiac conduction system pacing therapy, monitoring cardiac electrical activity, and determining cardiac morphology using the newly configured, or adjusted, AV delay. If the cardiac morphology does not substantively match, or is not substantively equivalent to, the LBB capture morphology within, for example, a selected tolerance, then the cardiac conduction system pacing therapy may be adjusted by decreasing the AV delay by, for example, an AV adjustment value or percentage as described herein until the cardiac morphology substantively matches, or is substantively equivalent to, the LBB capture morphology within, for example, a selected tolerance. It is to be understood that the same bipolar pacing vector is utilized for the first adjustment cycle 344.

[0101] If the AV delay adjustments using the bipolar pacing vector are exhausted and the cardiac morphology still does not substantively match, or is still not substantively equivalent to, the LBB capture morphology, the bipolar pacing vector may be switched to a unipolar pacing vector 356. The unipolar pacing vector may include a cardiac conduction system pacing therapy pacing electrode positioned proximate the left bundle branch being configured as the cathode and a housing electrode located on the housing of an implanted IMD being configured as the anode. Then, the cardiac conduction system pacing therapy may again be adjusted by decreasing the AV delay by, for example, an AV adjustment value or percentage as described herein until the cardiac morphology substantively matches, or is substantively equivalent to, the LBB capture morphology within, for example, a selected tolerance 346. Ifthe cardiac morphology substantively matches, or is substantively equivalent to, the LBB capture morphology within, for example, a selected tolerance, then the method 300 may continue delivering cardiac conduction system pacing therapy, monitoring cardiac electrical activity, and determining cardiac morphology using the newly configured, or adjusted, AV delay. If the AV delay adjustments are exhausted and the cardiac morphology still does not substantively match, or is still not substantively equivalent to, the LBB capture morphology, then processes of FIG. 8 may cease and the parameters may be left as programmed 348.ILLUSTRATIVE EXAMPLES

[0102] While the present disclosure is not so limited, an appreciation of various aspects of the disclosure will be gained through a discussion of the specific illustrative examples provided below. Various modifications of the illustrative examples, as well as additional examples of the disclosure, will become apparent herein.

[0103] Example Exl : An implantable medical device comprising: a computing apparatus comprising processing circuitry, the computing apparatus operably coupled to a plurality of implantable electrodes configured to sense and pace a patient's heart, wherein the computing apparatus is configured to: initiate delivery of cardiac conduction system pacing therapy using a cardiac conduction system pacing vector using a first electrode and a second electrode of the plurality of implantable electrodes, wherein the first electrode is positioned proximate a portion of the patient's cardiac conduction system; monitor cardiac electrical activity using the plurality of implantable electrodes, determine a cardiac morphology based on the cardiac electrical activity, and adjust the cardiac conduction system pacing vector based on the cardiac morphology.

[0104] Example Ex2: A method comprising: delivering cardiac conduction system pacing therapy using a cardiac conduction system pacing vector using a first electrode and a second electrode of a plurality of implantable electrodes, wherein the first electrode is positioned proximate a portion of the patient's cardiac conduction system; monitoring cardiac electrical activity using the plurality of implantable electrodes; determining a cardiac morphology based on the cardiac electrical activity; and adjusting the cardiac conduction system pacing vector based on the cardiac morphology.

[0105] Example Ex3 : The device as in Example Exl or the method as in Example Ex2, wherein the portion of the patient's cardiac conduction system comprises the bundle of His.

[0106] Example Ex4: The device or method as in any one of Examples Ex 1-3, wherein the portion of the patient's cardiac conduction system comprises the left bundle branch.

[0107] Example Ex5: The device or method as in any one of Examples Ex 1-3, wherein the portion of the patient's cardiac conduction system comprises the right bundle branch.

[0108] Example Ex6: The device or method as in any one of Examples Ex 1-3, wherein the second electrode is positioned in the patient's right ventricle.

[0109] Example Ex7: The device or method as in any one of Examples Ex 1-6, wherein adjusting the cardiac conduction system pacing vector based on the cardiac morphology comprises changing the cardiac conduction system pacing vector to use a third electrode of the plurality of implantable electrodes instead of the second electrode of the plurality of implantable electrodes.

[0110] Example Ex8: The device or method as in Example Ex7, wherein the third electrode comprises a right atrial electrode located in the right atrium.

[0111] Example Ex9: The device or method as in Example Ex7, wherein the third electrode comprises a housing electrode coupled to a housing implanted subcutaneously.

[0112] Example ExlO: The device or method as in any one of Examples Ex 1-9, wherein adjusting the cardiac conduction system pacing vector based on the cardiac morphology comprises switching pacing polarity of the first electrode and the second electrode.

[0113] Example Exl 1 : The device or method as in any one of Examples Exl -10, wherein adjusting the cardiac conduction system pacing vector based on the cardiac morphology comprises: comparing the cardiac morphology of the cardiac electrical morphology to a representative morphology; and adjusting the cardiac conduction system pacing vector in response to the comparison of the cardiac morphology of the cardiac electrical morphology to the representative morphology indicating ineffective capture of the cardiac conduction system.

[0114] Example Exl2: The device or method as in Example Exl 1, wherein the cardiac morphology comprises R-wave morphology.

[0115] Example Exl3: The device or method as in any one of Examples Exl-12, wherein the cardiac conduction system pacing is delivered based on an atrioventricular (AV) delay, wherein the AV delay is a time period between an atrial event and delivery of a cardiac conduction system pace of the cardiac conduction system pacing therapy, wherein the computing apparatus is further configured to adjust AV delay based on the cardiac morphology.

[0116] Example Exl4: The device or method as in Example Exl3, wherein adjusting AV delay comprises: comparing the cardiac morphology of the cardiac electrical morphology to a representative morphology; and decreasing the AV delay in response to the comparison of the cardiac morphology of the cardiac electrical morphology to the representative morphology indicating ineffective cardiac conduction system pacing therapy.

[0117] Example Exl5: The device or method as in any one of Examples Exl-14, wherein monitoring cardiac electrical activity using the plurality of implantable electrodes comprises monitoring cardiac electrical activity using the first electrode and the second electrode.

[0118] Example Exl6: The device or method as in any one of Examples Exl-15, the device further comprising or the method further comprising providing the plurality of implantable electrodes to sense and pace a patient's heart.

[0119] Example Exl7: An implantable medical device comprising: a computing apparatus comprising processing circuitry, the computing apparatus operably coupled to a plurality of implantable electrodes configured to sense and pace a patient's heart, wherein the computing apparatus is configured to: initiate delivery of cardiac conduction system pacing therapy using a cardiac conduction system pacing vector using a first electrode and a second electrode of the plurality of implantable electrodes, wherein the first electrode is positioned proximate a portion of the patient's cardiac conduction system, wherein the delivery of cardiac conduction system pacing therapy is based on an atrioventricular (AV) delay, wherein the AV delay is a time period between an atrial event and delivery of a cardiac conduction system pace of the cardiac conduction system pacing therapy; monitor cardiac electrical activity using the plurality of implantable electrodes; determine a cardiac morphology based on the cardiac electrical activity; determine whether the cardiac conduction system pacing therapy is ineffective; adjust AV delay in response to determination that the cardiac conduction system pacing therapy being ineffective until exhaustion of the AV delayadjustments; and adjust the cardiac conduction system pacing vector in response to exhaustion of the AV delay adjustments.

[0120] Example Exl8: A method comprising: delivering cardiac conduction system pacing therapy using a cardiac conduction system pacing vector using a first electrode and a second electrode of a plurality of implantable electrodes, wherein the first electrode is positioned proximate a portion of the patient's cardiac conduction system, wherein the delivery of cardiac conduction system pacing therapy is based on an atrioventricular (AV) delay, wherein the AV delay is a time period between an atrial event and delivery of a cardiac conduction system pace of the cardiac conduction system pacing therapy; monitoring cardiac electrical activity using the plurality of implantable electrodes; determining a cardiac morphology based on the cardiac electrical activity; determining whether the cardiac conduction system pacing therapy is ineffective based on the cardiac morphology; adjusting AV delay in response to determination that the cardiac conduction system pacing therapy being ineffective until exhaustion of the AV delay adjustments; and adjusting the cardiac conduction system pacing vector in response to exhaustion of the AV delay adjustments.

[0121] Example Exl9: The device as in Example Ex 17 or the method as in Example Exl8, wherein the portion of the patient's cardiac conduction system comprises the bundle of His.

[0122] Example Ex20: The device as in Example Ex 17 or the method as in Example Exl8, wherein the portion of the patient's cardiac conduction system comprises the left bundle branch.

[0123] Example Ex21 : The device as in Example Ex 17 or the method as in Example Exl8, wherein the portion of the patient's cardiac conduction system comprises the right bundle branch.

[0124] Example Ex22: The device or method as in any one of Examples Exl7-21, wherein the second electrode is positioned in the patient's right ventricle.

[0125] Example Ex23: The device or method as in any one of Examples Exl7-22, wherein adjusting the cardiac conduction system pacing vector comprises changing the cardiac conduction system pacing vector to use a third electrode of the plurality of implantable electrodes instead of the second electrode of the plurality of implantable electrodes.

[0126] Example Ex24: The device or method as in Example Ex23, wherein the third electrode comprises a right atrial electrode located in the right atrium.

[0127] Example Ex25: The device or method as in Example Ex23, wherein the third electrode comprises a housing electrode coupled to a housing implanted subcutaneously.

[0128] Example Ex26: The device or method as in any one of Examples Exl7-25, wherein adjusting the cardiac conduction system pacing vector comprises switching pacing polarity of the first electrode and the second electrode.

[0129] Example Ex27: The device or method as in any one of Examples Exl7-26, wherein adjusting the cardiac conduction system pacing vector comprises: comparing the cardiac morphology of the cardiac electrical morphology to a representative morphology; and adjusting the cardiac conduction system pacing vector in response to the comparison of the cardiac morphology of the cardiac electrical morphology to the representative morphology indicating ineffective capture of the cardiac conduction system.

[0130] Example Ex28: The device or method as in Example Ex27, wherein the cardiac morphology comprises R-wave morphology.

[0131] Example Ex29: The device or method as in any one of Examples Exl7-28, wherein monitoring cardiac electrical activity using the plurality of implantable electrodes comprises monitoring cardiac electrical activity using the first electrode and the second electrode.

[0132] Example Ex30: The device or method as in any one of Examples Exl7-29, the device further comprising or the method further comprising providing the plurality of implantable electrodes to sense and pace a patient's heart.

[0133] This disclosure has been provided with reference to illustrative embodiments and examples and is not meant to be construed in a limiting sense. As described previously, one skilled in the art will recognize that other various illustrative applications may use the techniques as described herein to take advantage of the beneficial characteristics of the devices and methods described herein. Various modifications of the illustrative embodiments and examples will be apparent upon reference to this description.

[0134] In one or more examples, the described techniques may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, thefunctions 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 non-transitory computer-readable media, which corresponds to a tangible medium such as data storage media (e.g., RAM, ROM, EEPROM, flash memory, or any other medium that can be used to store desired program code in the form of instructions or data structures and that can be accessed by a computer).

[0135] 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. Accordingly, the term “processor” as used herein may refer to any of the foregoing structure or any other physical structure suitable for implementation of the described techniques. Also, the techniques could be fully implemented in one or more circuits or logic elements.

[0136] 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.

[0137] All scientific and technical terms used herein have meanings commonly used in the art unless otherwise specified. The definitions provided herein are to facilitate understanding of certain terms used frequently herein and are not meant to limit the scope of the present disclosure.

[0138] 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 contrary, 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 typical ranges of experimental error.

[0139] The recitation of numerical ranges by endpoints includes all numbers subsumed within that range (e.g., 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, and 5) and any range within that range. Herein, the terms “up to” or “no greater than” a number (e.g., up to 50) includes the number (e.g., 50), and the term “no less than” a number (e.g., no less than 5) includes the number (e.g., 5).

[0140] The terms “coupled” or “connected” refer to elements being attached to each other either directly (in direct contact with each other) or indirectly (having one or more elements between and attaching the two elements). Either term may be modified by “operatively” and “operably,” which may be used interchangeably, to describe that the coupling or connection is configured to allow the components to interact to carry out at least some functionality (for example, a mobile user device may be operatively coupled to a cellular network transmit data to or receive data therefrom).

[0141] Reference to “one embodiment,” “an embodiment,” “certain embodiments,” or “some embodiments,” etc., means that a particular feature, configuration, composition, or characteristic described in connection with 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.

[0142] As used in this specification and the appended claims, the singular forms “a,” “an,” and “the” encompass embodiments having plural referents, unless the content clearly dictates otherwise. As used in this specification and the appended claims, the term “or” is generally employed in its sense including “and / or” unless the content clearly dictates otherwise.

[0143] 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.

[0144] The term “and / or” means one or all of the listed elements or a combination of at least two of the listed elements.

[0145] The phrases “at least one of,” “comprises at least one of,” and “one or more of’ followed by a list refers to any one of the items in the list and any combination of two or more items in the list.

Claims

CLAIMSWhat is claimed is:

1. An implantable medical device comprising: a computing apparatus comprising processing circuitry, the computing apparatus operably coupled to a plurality of implantable electrodes configured to sense and pace a patient’s heart, wherein the computing apparatus is configured to: initiate delivery of cardiac conduction system pacing therapy using a cardiac conduction system pacing vector using a first electrode and a second electrode of the plurality of implantable electrodes, wherein the first electrode is positioned proximate a portion of the patient’s cardiac conduction system; monitor cardiac electrical activity using the plurality of implantable electrodes, determine a cardiac morphology based on the cardiac electrical activity, and adjust the cardiac conduction system pacing vector based on the cardiac morphology.

2. An implantable medical device comprising: a computing apparatus comprising processing circuitry, the computing apparatus operably coupled to a plurality of implantable electrodes configured to sense and pace a patient’s heart, wherein the computing apparatus is configured to: initiate delivery of cardiac conduction system pacing therapy using a cardiac conduction system pacing vector using a first electrode and a second electrode of the plurality of implantable electrodes, wherein the first electrode is positioned proximate a portion of the patient’s cardiac conduction system, wherein the delivery of cardiac conduction system pacing therapy is based on an atrioventricular (AV) delay, wherein the AV delay is a time period between an atrial event and delivery of a cardiac conduction system pace of the cardiac conduction system pacing therapy; monitor cardiac electrical activity using the plurality of implantable electrodes; determine a cardiac morphology based on the cardiac electrical activity;determine whether the cardiac conduction system pacing therapy is ineffective; adjust AV delay in response to determination that the cardiac conduction system pacing therapy being ineffective until exhaustion of the AV delay adjustments; and adjust the cardiac conduction system pacing vector in response to exhaustion of the AV delay adjustments.

3. The device as in any one of claim 1 and claim 2, wherein the portion of the patient’s cardiac conduction system comprises the bundle of His.

4. The device as in any one of claim 1 and claim 2, wherein the portion of the patient’s cardiac conduction system comprises the left bundle branch.

5. The device as in any one of claim 1 and claim 2, wherein the portion of the patient’s cardiac conduction system comprises the right bundle branch.

6. The device as in any one of claims 1-5, wherein the second electrode is positioned in the patient’s right ventricle.

7. The device as in any one of claims 1-6, wherein adjusting the cardiac conduction system pacing vector comprises changing the cardiac conduction system pacing vector to use a third electrode of the plurality of implantable electrodes instead of the second electrode of the plurality of implantable electrodes.

8. The device as in claim 7, wherein the third electrode comprises a right atrial electrode located in the right atrium.

9. The device as in claim 7, wherein the third electrode comprises a housing electrode coupled to a housing implanted subcutaneously.

10. The device as in any one of claims 1-9, wherein adjusting the cardiac conduction system pacing vector comprises switching pacing polarity of the first electrode and the second electrode.

11. The device as in any one of claims 1 and 3-5, wherein adjusting the cardiac conduction system pacing vector based on the cardiac morphology comprises: comparing the cardiac morphology of the cardiac electrical morphology to a representative morphology; and adjusting the cardiac conduction system pacing vector in response to the comparison of the cardiac morphology of the cardiac electrical morphology to the representative morphology indicating ineffective capture of the cardiac conduction system.

12. The device as in claim 11, wherein the cardiac morphology comprises R-wave morphology.

13. The device as in any one of claims 1, 3-5, 11, and 12, wherein the cardiac conduction system pacing is delivered based on an atrioventricular (AV) delay, wherein the AV delay is a time period between an atrial event and delivery of a cardiac conduction system pace of the cardiac conduction system pacing therapy, wherein the computing apparatus is further configured to adjust AV delay based on the cardiac morphology.

14. The device as in claim 2 and 13, wherein adjusting AV delay comprises: comparing the cardiac morphology of the cardiac electrical morphology to a representative morphology; anddecreasing the AV delay in response to the comparison of the cardiac morphology of the cardiac electrical morphology to the representative morphology indicating ineffective cardiac conduction system pacing therapy.

15. The device as in any one of claims 1-14, wherein monitoring cardiac electrical activity using the plurality of implantable electrodes comprises monitoring cardiac electrical activity using the first electrode and the second electrode.

Images