Replacement of left ventricular activation time

Abstract

The present disclosure relates to an alternative left ventricular activation time (110, 107, 107A) representing or relating to a left ventricular activation time for use in determining a left bundle branch (LBB) (8a) capture and LBB pacing configuration. The alternative left ventricular activation time (110, 107, 107A) may be determined or measured from electrical activity monitored from one or more implanted electrodes (40, 42, 44, 46, 48, 50, 58, 61, 62, 64, 66) such as, for example, an LBB pacing electrode or an electrode located in the right ventricle (28).

Description

[0001] The present disclosure as a whole relates to the use of electrogram signal analysis to determine left bundle branch capture, for example, to ensure capture of the left bundle branch, rather than capture of the myocardial tissue of the heart. More specifically, the present disclosure relates to electrogram signal analysis, rather than electrocardiogram signal analysis, which, for example, may advantageously provide a more efficient means for determining left bundle branch capture, or may advantageously eliminate the need for a visit to a clinic.

[0002] Implantable medical devices (IMDs), such as pacemakers or implantable cardioverter-defibrillators, deliver therapeutic stimulation to the patient's heart, thereby improving the lives of millions of heart disease patients. Figure 1 As shown, conventional pacing techniques involve pacing one or more of the four chambers of the patient's heart 12, including the left atrium (LA) 33, the right atrium (RA) 26, the left ventricle (LV) 32, and the right ventricle (RV) 28. A common conventional therapeutic pacing technique for treating a slow heart rate (called bradycardia) involves delivering electrical pulses to the patient's right ventricular tissue. In response to the electrical pulses, both the right and left ventricles contract. However, because the pulse propagates from the right ventricle through the left ventricle, the heartbeat process may be significantly delayed. The electrical pulses pass through muscle cells called myocytes. Conduction between myocytes can be very slow. The delayed electrical pulses may cause the left ventricle to lose synchronization with the right ventricle.

[0003] Over time, the left ventricle can become very inefficient in pumping blood to the body. For some patients, heart failure may develop into a heart that is too weak to pump blood to the body. Heart failure can be a devastating diagnosis, because, for example, 50 percent of heart failure patients have a life expectancy of five years. Another possible cause of heart failure is atrial fibrillation, which is an irregular and often very fast heart rhythm or arrhythmia. During atrial fibrillation, for example, the atria of the heart may beat out of sync with the ventricles of the heart due to the arrhythmia of the atria, and this may cause tissue (such as blood) to clot in the heart or increase the risk of stroke or heart failure. In order to avoid the potential development of heart failure, some physicians have considered alternative pacing methods involving the cardiac conduction system. The cardiac conduction system can be described as being able to conduct electrical impulses quickly (e.g., similar to a car driving on a highway), while the paced heart muscle (myocardial) tissue can conduct electrical impulses more slowly (e.g., similar to a car driving on a muddy road).

[0004] The cardiac conduction system includes the sinoatrial node (SA node) 1, atrial internode bundles 2, 4, 5 (i.e., anterior internode 2, middle internode 4 and posterior internode 5), the atrioventricular node (AV node) 3, the His bundle 13 (also called the atrioventricular bundle or His bundle), and the left bundle branch 8a and the right bundle branch 8b. Figure 1Also shown are the aortic arch 6 and the Buckman bundle 7. The SA node, located at the junction of the superior vena cava and the right atrium, is considered the natural pacemaker of the heart because it continuously and repeatedly emits electrical pulses. The electrical pulses propagate through the muscles of the right atrium 26 to the left atrium 33 to cause synchronous contraction of the atria. The electrical pulses are also delivered to the atrioventricular (AV) node 3 through the atrial nodal bundle, which is the only connection between the atria and the ventricles. Conduction through the AV node tissue takes longer than through the atrial tissue, resulting in a delay between atrial contraction and the start of ventricular contraction. The AV delay (which is the delay between atrial contraction and ventricular contraction) allows the atria to empty blood into the ventricles. Then, before causing ventricular contraction via the branches of the His bundle, the valve between the atria and the ventricles closes. The His bundle 13 is located in the membrane atrioventricular septum near the tricuspid annulus. The His bundle 13 is divided into a left bundle branch 8a and a right bundle branch 8b, and is formed by specialized fibers called "Purkinje fibers" 9. Purkinje fibers 9 can be described as rapidly conducting action potentials along the ventricular septum (VS), rapidly extending the depolarization wave front through the remaining ventricular myocardium, and producing a coordinated contraction of the ventricular myocardium.

[0005] Although cardiac conduction system pacing therapy is increasingly being used as an alternative to traditional pacing techniques, cardiac conduction system pacing therapy has not been widely adopted for a variety of reasons. For example, cardiac conduction system pacing electrodes should be positioned within a precise target location (e.g., within about 1 mm) of a portion or region of the cardiac conduction system, such as the bundle of His, which can be difficult. In addition, it can be challenging to adjust the cardiac conduction system pacing therapy during delivery of therapy. Furthermore, it can also be challenging to determine whether the cardiac conduction system pacing therapy is selective (i.e., pacing only the cardiac conduction system) or non-selective (i.e., pacing both the cardiac conduction system and myocardial tissue). It is desirable to develop novel cardiac conduction system pacing therapy systems, devices, and methods and systems that overcome some of the disadvantages associated with previously performed cardiac conduction system pacing therapies. Summary of the invention

[0006] The present disclosure as a whole relates to the use of electrogram (EGM) signal analysis to determine left bundle branch (LBB) capture, for example to ensure capture of the LBB rather than capture of the myocardial tissue of the heart. LBB pacing is a physiological pacing method, and this method requires LBB capture. In contrast, left ventricular (LV) septal pacing captures and paces at the septum, which is not part of the cardiac conduction system. It may be difficult to implant a lead close enough to the LBB to effectively pace the LBB, or the implanted LBB lead may shift over time, for example due to natural movement or due to injury, and thus LV septal pacing may occur. In order to distinguish LBB pacing from LV septal pacing and ensure capture of the LBB, a standard 12-lead electrocardiogram (ECG) is typically used, and the resulting ECG signal is analyzed. Typically, the resulting ECG is used to determine the left ventricular (LV) activation time in order to distinguish LBB pacing from LV septal pacing. If the LV activation time remains short and constant under different pacing outputs, it is generally inferred that the LBB is captured rather than capturing the myocardial tissue of the heart.

[0007] Specifically, exemplary devices and methods are described herein to determine LBB capture using EGM signal analysis (rather than ECG signal analysis) and alternative LV activation times determined based on the EGM signal analysis. For example, using EGM signals rather than ECG signals can advantageously provide a more efficient or more effective analysis and can eliminate the need for a patient to visit a clinic to measure an ECG signal. Alternative LV activation times are detected from a cardiac conduction system pacing pulse (e.g., an LBB pacing pulse) to a sensed ventricular event (e.g., RV depolarization as measured using an electrical signal QRS morphology, etc.).

[0008] Alternative LV activation times can be used to determine effective LBB capture and effective LBB pacing using a variety of methods and applications as described herein. In one or more embodiments, exemplary devices and methods are described herein to periodically determine that effective LBB pacing therapy is being delivered, such as instead of LV septal pacing, so as to provide effective cardiac therapy to the patient over time. For example, effective LBB capture and LBB pacing may be desirable for a patient undergoing cardiac resynchronization therapy (CRT), or for another example, it may be desirable to ensure capture of the patient's right ventricle (RV).

[0009] Exemplary devices and methods may be described as utilizing at least a single chamber device solution for patients indicated for LBB pacing therapy, which solution may include one or more of a standard right atrial lead, a 3830 or 3830D lead for cardiac conduction system pacing, and a left ventricular lead.

[0010] An exemplary implantable medical device may include one or more implantable electrodes. The one or more implantable electrodes may include a left bundle branch (LBB) electrode. The LBB electrode may be capable of being positioned proximate to a portion of a patient's left bundle branch. The implantable medical device may also include a computing device. The computing device may include a processing circuit. The computing device may be capable of being operably coupled to the one or more implantable electrodes. The computing device may be configured to deliver LBB pacing proximate to the LBB using the LBB electrode in one or more pacing configurations. The computing device may be further configured to monitor electrical activity using the one or more implantable electrodes during the delivery of LBB pacing in the one or more pacing configurations. The computing device may be further configured to determine an alternative LV activation time based on the monitored electrical activity for each of the one or more pacing configurations. The alternative LV activation time may represent the LV activation time. The computing device may be further configured to determine whether LBB pacing has captured the LBB for each of the one or more pacing configurations based on the determined alternative LV activation time for each of the one or more pacing configurations.

[0011] An exemplary method may include delivering LBB pacing proximate to a left bundle branch (LBB) of a patient. Such delivery of LBB pacing may be performed using an LBB electrode positioned proximate to a portion of the LBB. Such delivery of LBB pacing may be performed in one or more pacing configurations. The method may also include monitoring electrical activity using one or more electrodes during delivery of LBB pacing in one or more pacing configurations. The method may also include determining an alternative LV activation time based on the monitored electrical activity for each of the one or more pacing configurations. The alternative LV activation time may represent the LV activation time. The method may also include determining whether LBB pacing has captured the LBB for each of the one or more pacing configurations based on the determined alternative LV activation time for each of the one or more pacing configurations.

[0012] The above summary is not intended to describe each embodiment or every implementation of the present disclosure. A more complete understanding will become apparent and appreciated by referring to the following detailed description and claims in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 is a schematic diagram of a patient's heart.

[0014] Figure 2A is a conceptual diagram illustrating an example of a therapy system (e.g., a three-chamber implantable medical device) that is configured to provide therapy to a patient's heart using an implantable medical device (IMD) via a His bundle or bundle branch pacing lead and a lead placed in the right ventricle or right atrium.

[0015] Figure 2Bis a schematic diagram illustrating an example of a His bundle or bundle branch pacing lead positioned in the His bundle in a cross-sectional view of the heart.

[0016] Figure 3A is a conceptual diagram illustrating an example therapy system (eg, a dual chamber implantable medical device) configured to include His bundle or bundle branch pacing leads using an IMD and a lead placed in the left ventricle.

[0017] Figure 3B is a schematic diagram illustrating an example of a His bundle or bundle branch pacing lead positioned in the His bundle in a cross-sectional view of a heart using an IMD.

[0018] Figure 3C is a cross-sectional view of a patient's heart implanted with implantable medical electrical leads to deliver bundle branch pacing.

[0019] Figure 3D yes Figure 3C A close up view of the leads in a patient's heart.

[0020] Figure 4 is a conceptual diagram illustrating an example of a therapy system (e.g., a dual-chamber implantable medical device) configured to provide therapy to a patient's heart using an IMD via a His bundle or bundle branch pacing lead and a lead placed in the left ventricle.

[0021] Figure 5 is an example Figure 2A as well as FIG. 3A to FIG. 4 A functional block diagram of an example configuration of an implantable medical device.

[0022] Figure 6 Based on Figure 2 to Figure 5 A block diagram of an illustrative method for utilizing monitored electrical activity by a device to determine effective LBB capture and LBB pacing.

[0023] Figure 7 is a depiction of exemplary ECG and EGM signals over time, illustrating the Figure 6 Alternative methods for determination of LV activation timing.

[0024] Figure 8 is an example such as Figure 7 Shown is a scatter plot of the correlation between the determined surrogate LV activation times and the measured LV activation times.

[0025] Fig. 9 is another depiction of exemplary ECG and EGM signals over time, illustrating the Figure 6 Alternative methods for determination of LV activation timing.

[0026] Fig.10 is an example such as Fig. 9 Shown is a scatter plot of the correlation between another different surrogate LV activation time determined and the LV activation time.

[0027] Fig.11 It can be used from Figure 2 to Figure 7 and Fig. 9 Block diagram of an illustrative method for utilizing an EGM signal to determine LBB capture by an apparatus, method, and process.

[0028] Fig.12 It can be used from Figure 2 to Figure 7 and Fig. 9 A block diagram of another illustrative method of utilizing an EGM signal to determine LBB capture by an apparatus, method, and process.

[0029] Fig.13 are scatter plots illustrating associated surrogate LV activation times and LVAT at various pacing outputs indicating effective LBB capture.

[0030] Fig.14 are scatter plots illustrating associated surrogate LV activation times and LVAT at various pacing outputs indicating ineffective LBB capture. DETAILED DESCRIPTION

[0031] In the following detailed description of exemplary embodiments, reference is made to the accompanying drawings, which form a part of the embodiments, and in which are shown by way of illustration specific embodiments that can be practiced. It should be understood that other embodiments can be utilized and the structural scope can be changed without departing from (e.g., still falling within) the scope of the present disclosure hereby presented.

[0032] Reference Figures 1 to 12 Describe exemplary systems, devices and methods. It will be apparent to those skilled in the art that elements or processes from one embodiment may be used in combination with elements or processes of other embodiments, and possible embodiments of such systems, devices and methods using the feature combinations set forth herein are not limited to the specific embodiments shown in the figures and / or described herein. Further, it will be appreciated that the embodiments described herein may include many elements that are not necessarily shown to scale. Further, it will be appreciated that the timing of the processes herein and the size and shape of the individual elements may be modified but still fall within the scope of the present disclosure, but certain timings, one or more shapes and / or sizes or element types may be superior to other timings, one or more shapes and / or sizes or element types.

[0033] Figure 1 is a schematic diagram of the heart 12 . Figure 2A and Figure 3A1 is a conceptual diagram illustrating an example therapy system 10 that can be used to provide therapy to heart 12 of patient 14. Patient 14 is typically, but not necessarily, a human. Therapy system 10 includes an IMD 16 coupled to leads 18, 20, 23 and a programmer 24. Leads 23 are located at Figure 2B 18 , 20 , 23. The bundle branches 8a, 8b and Purkinje fibers 9 are shown in isolation or individually relative to the heart 12. The IMD 16 may be, for example, an implantable pacemaker, cardioverter, and / or defibrillator that provides electrical signals to the heart 12 via electrodes coupled to one or more of the leads 18, 20, 23. Other non-limiting examples of the IMD 16 include: a pacemaker with medical leads, an implantable cardioverter-defibrillator (ICD), an intracardiac device, a leadless pacing device (LPD), a subcutaneous ICD (S-ICD), and a subcutaneous medical device (e.g., a neurostimulator, an insertable monitoring device, etc.).

[0034] Leads 18, 20, 23 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. Figure 2A In the example shown, the right ventricle (RV) lead 18 extends through one or more veins (not shown), the superior vena cava (not shown), and the right atrium (RA) 26, and into the right ventricle 28. The left ventricle (LV) coronary sinus lead 20 extends through one or more veins, the vena cava, the right atrium 26, and into the coronary sinus 30 to a region adjacent to the free wall of the left ventricle 32 of the heart 12. The cardiac conduction system pacing therapy lead 23 (e.g., a left bundle branch pacing lead, a right bundle branch pacing lead, a His bundle pacing lead, etc.) extends through one or more veins and the vena cava, and into the right atrium 26 of the heart 12 to pace the cardiac conduction system (e.g., Koch's triangle, septal wall, left bundle branch, right bundle branch, His bundle, etc.). In some embodiments, the cardiac conduction system pacing therapy lead 23 may be positioned within about 1 mm of Koch's triangle, septal wall, His bundle, or one or both bundle branches.

[0035] As used herein, cardiac conduction system pacing therapy refers to any pacing therapy configured to deliver pacing therapy (e.g., pacing pulses) to the cardiac conduction system, including, for example, the His bundle, left bundle branch, right bundle branch, etc. As used herein, the term "activation" refers to a sensed or paced event. For example, atrial activation can refer to atrial sensing or event (As) or atrial pacing or atrial pacing artifact (Ap). Similarly, ventricular activation can refer to ventricular sensing or event (Vs) or ventricular pacing or ventricular pacing artifact (Vp), which can be described as a ventricular stimulation pulse. In some embodiments, the activation interval or "activation time" from As or Ap to Vs or Vp and from Vp to Vs can be detected. Specifically, the activation interval may include pacing (Ap or Vp) to ventricular interval (LV or RV sensing) or atrial sensing (As) to ventricular sensing interval (LV or RV sensing). Further, the activation time may include a cardiac conduction system pacing pulse (e.g., LBB pacing pulse) to a ventricular interval, such as a sudden ventricular myocardial depolarization (RV sensing). A surrogate LV activation time is detected from a cardiac conduction system pacing pulse (e.g., LBB pacing pulse) to a sensed ventricular event (e.g., RV depolarization as measured using electrical signal QRS morphology, etc.).

[0036] IMD can be described as delivering one or both of conventional pacing therapy and cardiac conduction system pacing therapy. Conventional or traditional pacing therapy can be described as delivering pacing pulses to myocardial tissue that is not part of the cardiac conduction system of the patient's heart, such that, for example, the pacing pulse triggers electrical activation that propagates primarily from one myocardial cell to another (also referred to as "cell to cell"), as opposed to propagating within the cardiac conduction system before the myocardial tissue. For example, conventional pacing therapy can deliver pacing pulses directly to the muscular heart tissue to be depolarized to provide cardiac contraction. For example, conventional left ventricular pacing therapy can utilize an implanted left ventricular (LV) coronary sinus lead to extend through one or more veins, the vena cava, the right atrium and into the coronary sinus to reach an area adjacent to the free wall of the left ventricle of the heart to deliver pacing pulses to the myocardial tissue of the free wall of the left ventricle.

[0037] An example of a cardiac conduction system pacing therapy lead 23 (eg, a His lead) may be a SELECTSURE TM 3830. SELECTSURE TM For a description of the 3830 see Medtronic Model SELECTSURE TM 3830 Manual (2013), which is incorporated herein by reference in its entirety. TM 3830 includes two or more conductors with or without lumens.

[0038] An exemplary left ventricular lead having a set of spaced electrodes is shown in U.S. Patent Publication No. WO 2019 / 104174 A1, filed May 4, 2012 by Ghosh et al., and commonly assigned by the assignee of the present disclosure, the disclosure of which is incorporated herein by reference in its entirety. Exemplary electrodes on a lead for forming a pacing vector are shown and described in U.S. Patent Nos. US 8,355,784 B2, US 8,96S,5G7, and US 8,126,546, all of which are incorporated by reference and may implement features of the present disclosure.

[0039] Exemplary cardiac conduction system pacing therapy may be described, for example, in U.S. patent application publication No. 2019 / 0111270A1, entitled “His Bundle and Bundle Branch Pacing Adjustment,” published on April 18, 2019, which is incorporated herein by reference in its entirety.

[0040] The elongated conductor of the lead can extend through the sealed feedthrough assembly and be located within the insulating tubular member of the lead, and can electrically connect an electrical pulse generator (contained within the housing) to the spiral tip electrode or the cardiac conduction system electrode of the cardiac conduction system pacing therapy lead 23. The conductor can be formed by one or more conductive wires, such as MP35N alloy known to those of ordinary skill in the art, in a coiled or cabled configuration, and the insulating tubular member can be any suitable medical grade polymer, such as polyurethane, silicone rubber, or a mixture thereof. According to an exemplary embodiment, the flexible lead body extends from the proximal end of the housing to a predetermined length (e.g., about 10 centimeters (cm) to about 20 cm, or about 15 cm to 20 cm) to the other end. The size of the lead body is less than about 7 French (FR), but is typically in the range of about 3FR to 4FR. In one or more embodiments, a lead body of about 2FR to about 3FR size is used.

[0041] Cardiac conduction system pacing therapy may be performed via other leads. Another exemplary lead including two or more pacing electrodes may be used to deliver multi-site pacing pulses to the cardiac conduction system via the His bundle or one or both bundle branches. Multi-site pacing may be delivered simultaneously or sequentially, as described and illustrated in U.S. Patent Application Publication No. 2016 / 0339248, entitled “EFFICIENT DELIVERY OF MULTI-SITE PACING,” filed on April 21, 2016, the disclosure of which is incorporated herein by reference in its entirety.

[0042] Because electrodes in multi-site or multi-point stimulation may be in close proximity to one another, detecting and verifying effective capture of a single electrode during delivery of such therapy may be important. Delivering a multi-site pacing pulse may include delivering a pacing pulse to a first tissue site and a second tissue site via a first pacing electrode and a second pacing electrode, respectively, all of which may occur within the same cardiac cycle.

[0043] Specifically, a lead other than the LV coronary sinus lead 20 configured to perform multi-site pacing can be placed in the ventricular septum, with the first (distal) electrode toward the left side of the ventricular septum for left bundle branch pacing, and the second electrode (proximal) toward the right side of the septum for pacing the right bundle branch. The inter-electrode distance can be defined as the distance between the first electrode and the second electrode, or the distance between the electrodes. In some embodiments, the inter-electrode distance is at least about 3 millimeters, 4 millimeters, 5 millimeters, 6 millimeters, 7 millimeters, or 8 millimeters (mm). In some embodiments, the inter-electrode distance is at most about 15 mm, 14 mm, 13 mm, 12 mm, 11 mm, or 10 mm. For example, the inter-electrode distance can be in the range of about 6 mm to 12 mm. Once pacing is delivered, both the left and right bundle branches can be stimulated so that the two ventricles are naturally or nearly naturally synchronized. In contrast, in conventional CRT, the ventricles may be described as not being naturally synchronized.

[0044] A single lead including two (or more) pacing electrodes (eg, cathodes) can deliver cathodic pacing outputs at two separate locations (eg, the left and right bundle branches), thereby stimulating both bundle branches simultaneously.

[0045] Cardiac conduction system pacing may include at least one of the His bundle or left bundle branch pacing or right bundle branch pacing. Bundle branch pacing may bypass pathological areas and may have a low and stable pacing threshold. In some embodiments, only one bundle branch may be paced using a pacing lead. In another embodiment, two bundle branches may be paced simultaneously (e.g., dual bundle branch pacing), which may simulate the propagation of intrinsic activation via the His bundle-Purkinje conduction system, for example, the activation of pacing propagates to the two ventricles via the two bundle branches for synchronous contraction. On the other hand, conventional His bundle pacing typically paces the His bundle close to the bundle branch. 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. In some embodiments, the IMD 16 may be an intracardiac pacemaker or a leadless pacing device (LPD).

[0046] As used herein, "leadless" refers to a device that has no leads extending from the patient's heart 12. In other words, the leads of a leadless device may not extend from the outside of the patient's heart to the inside of the patient's heart. Some leadless devices can be introduced through a vein, but once implanted, the device does not or may not include any transvenous leads and can be configured to provide cardiac therapy without the use of any transvenous leads. In one or more embodiments, when the housing of the device is positioned in the atrium, an LPD for bundle pacing does not use leads to be operably connected to electrodes disposed proximate to the septum. The leadless electrodes can be coupled to the housing of the medical device without leads, without the use of leads between the electrodes and the housing.

[0047] IMD 16 may be coupled to at least one of leads 18, 20, 23 via an electrode ( FIG. 2A to FIG. 2B 12 (not shown) to sense electrical signals associated with depolarization and repolarization of heart 12. In some examples, IMD 16 provides pacing pulses to heart 12 based on the electrical signals sensed within heart 12. The configuration of the electrodes used by IMD 16 for sensing and pacing may be unipolar or bipolar. IMD 16 may also provide defibrillation therapy and / or cardioversion therapy via electrodes located on at least one of leads 18, 20, 23. IMD 16 may detect atrial arrhythmias of heart 12, such as atrial fibrillation of atria 26 and 33, and may deliver defibrillation therapy to heart 12 in the form of electrical pulses. In addition, IMD 16 may detect ventricular arrhythmias of heart 12, such as ventricular fibrillation of ventricles 28 and 32, and may deliver defibrillation therapy to heart 12 in the form of electrical pulses. In some examples, IMD 16 may be programmed to deliver a course of therapy, such as pulses with increasing energy levels, until the fibrillation of heart 12 ceases. IMD 16 may detect fibrillation using one or more fibrillation detection techniques known in the art.

[0048] In some examples, programmer 24 ( Figure 1 ) may be a handheld computing device or a computer workstation or a mobile phone. 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 be, for example, a cathode ray tube (CRT) display, a liquid crystal display (LCD), or a light emitting diode (LED) display. The keypad may take the form of an alphanumeric keypad or a reduced set of keys associated with specific functions. Programmer 24 may additionally or alternatively include a peripheral pointing device such as a mouse, and the user may interact with the user interface via the peripheral pointing device. In some embodiments, the display of programmer 24 may include a touch screen display, and the user may interact with programmer 24 via the display. Through a graphical user interface on programmer 24, the user may select one or more optimization parameters.

[0049] In addition, various pacing settings can be adjusted or configured based on various sensed signals. For example, various near-field signals and far-field signals can be sensed by one or more electrodes of the IMD 16 and / or other devices operatively coupled thereto. For example, the Vp to QRS end or offset within the near-field signal or the far-field signal can be used to adjust or configure the AV delay of a cardiac conduction system pacing therapy. In addition, for example, the QRS within the near-field signal or the far-field signal can be used to adjust or configure the VV delay between a cardiac conduction system pacing therapy and a conventional left ventricular pacing therapy. The QRS duration is the time from when the Q wave is detected until the S wave ends.

[0050] In one or more embodiments, the near-field or far-field signals can be used to determine an alternative LV activation time, which in turn can be used to determine effective LBB capture and LBB pacing. The alternative LV activation time can be an activation time as described above, including a cardiac conduction system pacing pulse (e.g., an LBB pacing pulse) to a sudden ventricular myocardial depolarization (e.g., RV depolarization as measured using an electrical signal QRS morphology).

[0051] Each of the following exemplary embodiments will be discussed in greater detail herein. For example, one or more EGM signals may be monitored at multiple AV delays or at multiple pacing rates during the delivery of LBB pacing and then analyzed to determine an alternative LV activation time that can be used to determine effective LBB capture. For example, the use of EGM signals can advantageously provide a more efficient or more effective determination of LBB capture and can further eliminate the need for a patient to visit a clinic in person to use an ECG placed on the patient by a medical provider. Although EGM signals are described as being utilized, it should be understood that any other type of electrical signal known to those skilled in the art may be monitored.

[0052] For example, electrical activity signals may be acquired from the right ventricle (RV) or any other place in or around the heart, such as the LBB, left ventricle (LV), etc. For example, a QRS peak within the monitored electrical activity may be used to determine an alternative LV activation time, and effective LBB capture may then be determined based on the alternative LV activation time. Also, for example, a maximum slope prior to a QRS peak within the monitored electrical activity may be used to determine an alternative LV activation time, and effective LBB capture and pacing may then be determined based on the alternative LV activation time.

[0053] Further, the near-field and / or far-field electrical signals can be used to determine a target pacing setting that induces a specific QRS morphology or induces a specific QRS morphology over time. For one example, the far-field electrical signals can be sensed in a far-field electrogram (EGM) monitored by the IMD 16 and corresponding leads or a separate device (such as a subcutaneously implanted device).

[0054] As used herein, the term "far-field" electrical signal refers to the result of measuring cardiac activity using sensors or electrodes located outside the region of interest. For example, an EGM signal measured from an electrode positioned outside the RV (or heart chamber of interest) of a patient's heart is an example of a far-field electrical signal of the patient's heart. The sensor or electrode may be positioned in a chamber adjacent to the heart chamber of interest.

[0055] As used herein, the term "near field" electrical signal refers to the result of measuring cardiac activity using sensors or electrodes positioned near a region of interest. For example, an EGM signal measured from an electrode positioned on the right side of a patient's ventricular septum is an example of a near field electrical signal of the patient's RV.

[0056] R wave timing is the time in which the QRS is detected. Typically, R wave timing includes using the maximum first derivative of the rising edge of the R wave (or the time of maximum R wave value). R wave timing is also used in the device marker channel to indicate the R wave time or ventricular activation time.

[0057] Pace-RV sense or pace-LV sense (e.g., pace to RV sense or pace to LV sense) is the time interval from pacing (or pacing artifact) to the RV or LV sense time. For example, if pace-RV sense is much longer than pace-LV sense, this may indicate that LV activation occurs much earlier than RV activation (thus pace-RV sense is longer), then RV pacing can be delivered synchronously with bundle pacing, so RV activation and LV activation can occur approximately simultaneously.

[0058] A user, such as a physician, technician, or other clinician, may interact with programmer 24 to communicate with IMD 16. For example, a user may interact with programmer 24 to retrieve physiological or diagnostic information from IMD 16. Medtronic AMPLIAMRI™ CRT-D SURESCAN TM An exemplary IMD 16 is described in the DTMB2D1 manual, which is incorporated herein by reference in its entirety.A user may also interact with programmer 24 to program IMD 16, eg, to select values ​​for operating parameters of the IMD.

[0059] IMD 16 and programmer 24 may communicate via wireless communication using any technique known in the art. Examples of communication techniques may include, for example, low frequency or radio frequency (RF) telemetry, although other techniques are also contemplated. In some examples, programmer 24 may include programming leads that may be placed proximate to the patient's body near the implant site of IMD 16 to improve the quality or safety of communication between IMD 16 and programmer 24.

[0060] Figure 3A is a conceptual diagram illustrating IMD 16 and leads 18, 20, 23 of therapy system 10 in greater detail. Three-chamber IMD 16 may be used for cardiac rhythm therapy and defibrillation or cardioversion therapy (CRT-D). 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 are electrically coupled to corresponding electrical contacts within connector block 34. Additionally, in some examples, leads 18, 20, 23 may be mechanically coupled to connector block 34 by means of set screws, connecting pins, or another suitable mechanical coupling mechanism.

[0061] Each of leads 18, 20, 23 includes an elongated insulated lead body that may carry a plurality of concentric coiled conductors separated from one another by a tubular insulating sheath. In the illustrated example, optional pressure sensor 38 and bipolar electrodes 40 and 42 are positioned proximate the distal end of lead 18. Additionally, bipolar electrodes 44 and 46 are positioned proximate the distal end of lead 20, and bipolar electrodes 48 and 50 are positioned proximate the distal end of lead 23. Figure 3A In the embodiment of the present invention, pressure sensor 38 is disposed in right ventricle 28. Pressure sensor 38 can be responsive to absolute pressure within right ventricle 28 and can be, for example, a capacitive or piezoelectric absolute pressure sensor. In other examples, pressure sensor 38 can be positioned in other areas of heart 12 and can monitor pressure within one or more of the other areas of heart 12, or pressure sensor 38 can be positioned elsewhere within or near the cardiovascular system of patient 14 to monitor cardiovascular pressure associated with mechanical contraction of the heart. Optionally, a pressure sensor in the pulmonary artery in communication with IMD 16 can be used.

[0062] Electrodes 40, 44, and 48 may take the form of ring electrodes, and electrodes 42, 46, and 50 may take the form of extendable and / or fixed spiral tip electrodes mounted within insulating electrode heads 52, 54, and 56, respectively. Each of electrodes 40, 42, 44, 46, 48, and 50 may be electrically coupled to a respective one of the coil conductors within the lead body of its associated lead 18, 20, 23, and thereby to a respective one of the electrical contacts on the proximal ends of leads 18, 20, and 23.

[0063] Electrodes 40, 42, 44, 46, 48, and 50 may sense electrical signals associated with depolarization and repolarization of heart 12. The electrical signals are conducted to IMD 16 via respective leads 18, 20, and 23. In some examples, IMD 16 also delivers pacing pulses via electrodes 40, 42, 44, 46, 48, and 50 to cause depolarization of cardiac tissue of heart 12. In some examples, such as FIG. 3A to FIG. 3B As shown, IMD 16 includes one or more housing electrodes, such as housing electrode 58, which may be integrally formed with an outer surface of an airtight housing 60 of IMD 16 or otherwise coupled to housing 60. In some examples, housing electrode 58 may be defined by an uninsulated portion of an outwardly facing portion of housing 60 of IMD 16. Electrode 50 may be used for pacing and / or sensing of cardiac conduction system tissue (e.g., LBB, His bundle, or other bundle branch tissue such as RBB). Other separations between insulated and non-insulated portions of housing 60 may be used to define two or more housing electrodes. In some examples, housing electrode 58 substantially includes all of housing 60. Any of electrodes 40, 42, 44, 46, 48, 50 may be used in combination with housing electrode 58 for unipolar sensing or pacing, or for bipolar sensing with two electrodes in the same pacing lead. In one or more embodiments, housing 60 may enclose a stimulation generator (see Figure 5 ), and a sensing module for monitoring the patient's heart rhythm.

[0064] Leads 18, 20, 23 may also include elongated electrodes 62, 64, 66, respectively, which may take the form of coils. IMD 16 may deliver a defibrillation shock to heart 12 via any combination of elongated electrodes 62, 64, 66 and housing electrode 58. Electrodes 58, 62, 64, 66 may also be used to deliver cardioversion pulses to heart 12. Electrodes 62, 64, 66 may be made of any suitable conductive material, such as, but not limited to, platinum, platinum alloys, or other materials known to be useful in implantable defibrillation electrodes.

[0065] The pressure sensor 38 may be coupled to one or more coil conductors within the lead 18. Figure 3AIn some examples, pressure sensor 38 is located on lead 18 more distally than elongated electrode 62. In other examples, pressure sensor 38 may be located closer to elongated electrode 62, rather than distal to electrode 62. Furthermore, in other examples, pressure sensor 38 may be coupled to another of leads 20, 23, or to leads other than leads 18, 20, 23 that carry stimulation and sensing electrodes. Additionally, in some examples, pressure sensor 38 may be a stand-alone device implanted within heart 12, such as within a septum that separates right ventricle 28 from left ventricle 32, or within a septum that separates right atrium 26 from left atrium 33. In such examples, pressure sensor 38 may communicate wirelessly with IMD 16.

[0066] Figure 3B IMD 16 is shown coupled to leads 18, 20, 22, 23. Right atrial (RA) lead 22 may extend through one or more veins and the vena cava and into the right atrium 26 of heart 12. RA lead 22 may be connected to a three-chamber IMD 16, for example, using a Y-adapter. IMD 16 may be used for cardiac rhythm therapy and defibrillation or cardioversion therapy (CRT-D). RA lead 22 may include electrodes that are the same or similar to those of leads 18, 20, 23, such as ring electrodes 40, 44, and 48, extendable helical tip electrodes 42, 46, and 50, and / or elongated electrodes 62, 64, 66 in the form of a coil.

[0067] FIG. 3C to FIG. 3D A patient's heart 12 implanted with an IMD 716 is shown operably coupled to implantable medical electrical leads 723 to deliver bundle branch pacing according to one example of an IMD system 710 . Figure 3D yes Figure 3C A close up view of lead 723 in patient's heart 12. In some embodiments, electrical lead 723 may be the only lead implanted in patient's heart 12.

[0068] Specifically, lead 723 can be configured for dual-branch or single-branch pacing. Lead 723 can be connected to lead 23 ( FIG. 2A to FIG. 2B ) is the same or similar to the lead 723, except that the lead 723 is implanted in the bundle branch rather than, for example, near the His bundle 13. As shown, the lead 723 is implanted in the septal wall from the RV 28 toward the LV 32. The lead 723 may not pierce the wall of the LV 32 or extend into the LV chamber. The electrode 752 and the tissue-piercing electrode assembly 761 may be disposed on the distal end portion of the lead 723, which may also be described as a shaft. The electrode 752 and the tissue-piercing electrode assembly 761 may be arranged with the electrode and tissue-piercing electrode assembly 50 ( Figure 3A), except that electrode 752 is configured as a cathode electrode to sense or pace the RBB and electrode assembly 761 is configured to sense or pace the LBB, for example, during dual-branch pacing. Thus, electrode 752 can be implanted near RBB 8b and electrode assembly 761 can be implanted near LBB 8a. During single-branch pacing, for example, one of electrode 752 and electrode assembly 761 can be used to pace only the RBB or the LBB, respectively.

[0069] Electrode assembly 761 may be described as a monopolar cathode electrode that may be implanted toward the left side of a patient's diaphragm. Electrode 752 may be described as a monopolar cathode electrode that may be implanted toward the right side of a patient's diaphragm.

[0070] During dual-branch pacing, both electrode 752 and electrode assembly 761 (which also includes electrodes) can each deliver cathodic pulses to achieve synchronized activation or excitation of RBB 8b and LBB 8a, which can result in synchronized activation of RV 28 and LV 32. In some embodiments, the pulses can be delivered simultaneously to achieve synchronization. In other embodiments, the pulses can be delivered with a delay to achieve synchronization.

[0071] Lead 723 can include electrode 770 disposed closer to electrode 752 and electrode assembly 761. Electrode 770 can be positioned in or near RA 26 and can serve as an anode for cathodic pulses from electrode 752 and / or electrode assembly 761.

[0072] Figures 2A to 4 The configuration of the treatment system 10 shown is only one example. In other examples, the treatment system may include epicardial leads and / or patch electrodes instead of or in addition to Figures 2A to 4 14, or other configurations shown or described herein or incorporated by reference. In addition, IMD 16 need not be implanted in patient 14. In examples where IMD 16 is not implanted in patient 14, IMD 16 can deliver defibrillation shocks and other therapies to heart 12 via percutaneous leads extending through the skin of patient 14 to various locations inside or outside of heart 12.

[0073] In other examples of a therapy system that provides electrical stimulation therapy to heart 12, such a therapy system may include any suitable number of leads coupled to IMD 16, and each of the leads may extend to any location within or near heart 12. For example, a therapy system may include, for example, Figures 2A to 4 Three transvenous leads are shown positioned with an additional lead positioned in or near the left atrium 33 ( Figure 1As another example, the therapy system may include a single lead extending from IMD 16 into right atrium 26 or right ventricle 28 or two leads extending into a respective one of right ventricle 28 and right atrium 26. FIG. 3A to FIG. 3B An example of this type of therapy system is shown. If four leads are required for therapy delivery, the IS-1 connector can be used in conjunction with a Y-adapter 25 extending from the RA port of the connector. The Y-adapter allows two separate leads (e.g., a right atrial lead and a bundle pacing bundle lead) to extend from two separate legs of the "Y", while the single leg is inserted into the connector block 34 on the IMD 16.

[0074] Figure 4 is a conceptual diagram illustrating another example of the treatment system 70 . Figure 4 The illustrated therapy system 70 may be used to provide defibrillation and pacing pulses to the heart 12. The therapy system 70 is similar to FIG. 2A to FIG. 2B or FIG. 3A to FIG. 3D Therapy system 10 of the present invention is similar to that of the present invention, but includes two leads 18, 23 instead of three leads. Therapy system 70 can utilize an IMD 16 configured to deliver or perform dual-chamber pacing. Leads 18, 23 are implanted in the right ventricle 28 and 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.

[0075] The cardiac conduction system pacing lead 23 can be in the form of a spiral (also referred to as a spiral electrode) that can be positioned near, adjacent to, adjacent to, or in an area or portion of the cardiac conduction system, such as the ventricular septum, Koch's triangle, His bundle, left bundle branch tissue, and / or right bundle branch tissue. The cardiac conduction system pacing lead 23 can be configured as a bipolar lead or a quadripolar lead that can be used with a pacemaker device, a CRT-P device, or a CRT-ICD.

[0076] Figure 58 is a functional block diagram of an example configuration of an IMD 16, including a processor 80, a memory 82, a stimulation generator 84 (e.g., an electrical pulse generator or signal generating circuit), a sensing module 86 (e.g., a sensing circuit), a telemetry module 88, and a power source 90. One or more components of the IMD 16, such as the processor 80, may be housed within a housing of the IMD 16 (e.g., housed 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 the 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), a read-only memory (ROM), a non-volatile RAM (NVRAM), an electrically erasable programmable ROM (EEPROM), a flash memory, or any other digital media.

[0077] The processor 80 may include any one or more of the following: a microprocessor, a controller, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), or an equivalent discrete or integrated logic circuit. In some examples, the 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) and other discrete or integrated logic circuits. The functions of the processor 80 attributed to this article may be embodied as software, firmware, hardware, or any combination thereof. The processor 80 controls the stimulation generator 84 to deliver stimulation therapy to the heart 12 according to one or more of the selected treatment programs (e.g., optimization of AV delay, VV delay, VV delay, etc.), and the treatment program can be stored in the memory 82. Specifically, the processor 80 can control the stimulation generator 84 to deliver electrical pulses having an amplitude, pulse width, frequency, or electrode polarity specified by the selected one or more treatment programs.

[0078] In some embodiments, RA lead 22 can be operably coupled to electrode 61, which can be used to monitor or pace RA. Stimulation generator 84 can be electrically coupled to electrodes 40, 42, 44, 46, 48, 50, 58, 61, 62, 64, and 66, for example, via conductors of respective leads 18, 20, 22, 23 or, in the case of housing electrode 58, via electrical conductors disposed within housing 60 of IMD 16. Stimulation generator 84 can be configured to generate and deliver electrical stimulation therapy to heart 12. For example, stimulation generator 84 can deliver a defibrillation shock to heart 12 via at least two of electrodes 58, 62, 64, 66. Stimulation generator 84 can deliver pacing pulses via ring electrodes 40, 44, 48 coupled to leads 18, 20, and 23, respectively, and / or via helical electrodes 42, 46, or 50 of leads 18, 20, or 23, respectively. Cardiac conduction system pacing therapy can be delivered via cardiac conduction system lead 23 connected to an atrial, RV, or LV connection port of connector block 34. In some embodiments, cardiac conduction system pacing therapy can be delivered via leads 18 and / or 23. In some examples, stimulation generator 84 delivers pacing, cardioversion, or defibrillation stimulation in the form of electrical pulses. In other examples, stimulation generator 84 can 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.

[0079] Stimulation generator 84 may include a switch module, and processor 80 may use the switch module to select which of the available electrodes is used to deliver a defibrillation shock or pacing pulse, for example, via a data / address bus. The switch module may include a switch array, a switch matrix, a multiplexer, or any other type of switching device suitable for selectively coupling stimulation energy to selected electrodes.

[0080] The sensing module 86 monitors a signal from at least one of the electrodes 40, 42, 44, 46, 48, 50, 58, 61, 62, 64, or 66 to monitor the electrical activity of the heart 12, such as via an electrocardiogram (ECG) signal and / or an electrogram (EGM). The sensing module 86 may also include a switch module to select which of the available electrodes is used to sense cardiac activity. In some examples, the processor 80 may select an electrode to act as a sensing electrode via a switch module within the sensing module 86, such as by providing a signal 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 a signal from the processor 80, the switch module may connect an output from a selected electrode to one of the sensing channels.

[0081] In some examples, one channel of sensing module 86 may include an R-wave amplifier that receives signals from electrodes 44, 46 used for pacing and sensing in the left ventricle 32 near heart 12. Another channel may include another R-wave amplifier that receives signals from electrodes 40, 42 used for pacing and sensing in the right ventricle 28 of heart 12. In some examples, the R-wave amplifier may take the form of an automatic gain control amplifier that provides an adjustable sensing threshold based on the R-wave amplitude of the measured heart rate.

[0082] Additionally, in some examples, one channel of the sensing module 86 may include a P-wave amplifier that receives signals from electrodes 48, 50 that are used for pacing and sensing in the right atrium 26 of the heart 12. In some examples, the P-wave amplifier may take the form of an automatic gain control amplifier that provides an adjustable sensing threshold based on the P-wave amplitude of the measured heart rate. Examples of R-wave amplifiers and P-wave amplifiers are described in U.S. Patent No. 5,117,824, entitled "APPARATUS FOR MONITORING ELECTRICAL PHYSIOLOGIC SIGNALS," issued to Keimel et al. on June 2, 1992, which is incorporated herein by reference in its entirety. Other amplifiers may also be used. In addition, in some examples, one or more of the sensing channels of the sensing module 86 can be selectively connected to the shell electrode 58 or the slender electrodes 62, 64 or 66, together with or in place of one or more of the electrodes 40, 42, 44, 46, 48 or 50, for example for unipolar sensing of R waves or P waves in any of chambers 26, 28 or 32 of the heart 12.

[0083] In some examples, the sensing module 86 includes a channel including an amplifier having a relatively wider passband than an R wave amplifier or a P wave amplifier or a high resolution amplifier having a relatively narrow passband for recording of His bundle or bundle branch potentials. Signals from selected sensing electrodes selected for connection to this broadband amplifier may be provided to a multiplexer and thereafter converted by an analog-to-digital converter into a multi-bit digital signal for storage in a 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 the memory 82 to detect and classify the patient's heart rhythm from the electrical signals. The processor 80 may detect and classify the patient's heart rhythm by employing any of numerous signal processing methods known in the art.

[0084] If the IMD 16 is configured to generate and deliver pacing pulses to the heart 12, the processor 80 may include a pacemaker timing and control module, which may be embodied in hardware, firmware, software, or any combination thereof. The pacemaker timing and control module may include a dedicated hardware circuit such as an ASIC that is separate from other 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 an ASIC. The pacemaker timing and control module may include a programmable counter that controls basic time intervals associated with DDD, VVI, DVI, VDD, AAI, DDI, DDDR, VVIR, DVIR, VDDR, AAIR, DDIR, and other single-chamber and dual-chamber pacing modes. In the aforementioned pacing modes, "D" may indicate dual chamber, "V" may indicate ventricle, "I" may indicate inhibited pacing (e.g., no pacing), and "A" may indicate atrium. The first letter in the pacing mode may indicate the chamber that is paced, the second letter may indicate the chamber in which the electrical signal is sensed, and the third letter may indicate the chamber in which the response to the sensing is provided.

[0085] The intervals defined by the pacemaker timing and control module can include atrial and ventricular pacing escape intervals, refractory periods during which sensed P and R waves are ineffective for restarting the timing of the escape interval, and pulse widths of pacing pulses. As another example, the pacemaker timing and control module can define blanking periods and provide signals from the sensing module 86 to blank one or more channels, such as amplifiers, for a period of time during and after the delivery of electrical stimulation to the heart 12. The duration of these intervals can be determined by the processor 80 in response to data stored in the memory 82. The pacemaker timing and control module can also determine the amplitude of the cardiac pacing pulses.

[0086] During pacing, an escape interval counter within the pacemaker timing / control module may be reset when R and P waves are sensed. The stimulation generator 84 may include a pacemaker output circuit that is selectively coupled, for example, via a switch module, to any combination of electrodes 40, 42, 44, 46, 48, 50, 58, 61, 62, or 66 suitable for delivering bipolar or unipolar pacing pulses to one of the chambers of the heart 12. The processor 80 may reset the escape interval counter when a pacing pulse is generated by the stimulation generator 84, and thereby control the basic timing of cardiac pacing functions including anti-tachyarrhythmia pacing.

[0087] In some examples, processor 80 may operate as an interrupt driven device and respond to interrupts from a pacemaker timing and control module, where the interrupts may correspond to the occurrence of sensed P and R waves and the generation of cardiac pacing pulses. Any necessary mathematical calculations are performed by processor 80, and any updates of values ​​or intervals controlled by the pacemaker timing and control module of processor 80 may occur following such interrupts. A portion of memory 82 may be configured as a plurality of recirculating buffers capable of maintaining a series of measured intervals that may be analyzed by processor 80 in response to the occurrence of a pacing or sensing interruption to determine whether the patient's heart 12 is currently exhibiting an atrial or ventricular tachyarrhythmia.

[0088] Telemetry module 88 includes a module for communicating with another device such as programmer 24 ( Figure 2A ) communications. Telemetry module 88, under the control of processor 80, may receive downlink telemetry from programmer 24 and send uplink telemetry to the programmer via an antenna, which may be internal and / or external. Processor 80 may provide data to be uplinked to programmer 24 and control signals for telemetry circuitry within telemetry module 88, for example, via an address / data bus. In some examples, telemetry module 88 may provide received data to processor 80 via a multiplexer.

[0089] The various components of IMD 16 are coupled to a power source 90, which may include rechargeable or non-rechargeable batteries. Non-rechargeable batteries may be selected to last for several years, while rechargeable batteries may be inductively charged from an external device, for example, on a daily or weekly basis.

[0090] The exemplary devices and methods described herein can provide and use monitored electrical activity (e.g., EGM, etc.) to determine effective LBB capture to provide effective LBB pacing for cardiac therapy, such as, for example, cardiac resynchronization therapy (CRT), biventricular pacing, etc. In addition, the monitored electrical activity can be used to determine alternative LV activation times, which in turn can be used to determine effective LBB capture. As will be further described herein, the electrical activity of the heart can be monitored for specific areas of the heart, such as specific chambers (e.g., RV, LV), and can be acquired using various devices (e.g., EGM) as described herein.

[0091] The LV activation time of the replacement can be determined, for example, by analyzing the monitored electrical activity. In one embodiment, the monitored electrical activity may include one or more EGM signals monitored from the RV using the RV tip electrode as described herein. The LV activation time of the replacement can be determined or measured from the transfer of the pacing pulse to the cardiac conduction system (e.g., LBB) to the reference point in one or more EGM signals. For example, the LV activation time of the replacement can be determined or measured from the QRS peak value in the EGM signal delivered to the cardiac conduction system (e.g., LBB). In addition, for example, the LV activation time of the replacement can be determined or measured from the maximum slope of the signal before the QRS peak value in the EGM signal delivered to the cardiac conduction system (e.g., LBB). It should be understood that any other EGM signal parameters can be used. In any case, the determined LV activation time of the replacement can be used to determine effective LBB capture and effective LBB pacing. For example, EGM signal parameters and the resulting determined LV activation time of the replacement can be monitored and determined under different pacing settings. If the LV activation time of the replacement remains consistent under different pacing settings, this can indicate the effective capture of LBB. In another embodiment, if the surrogate LV activation times remain consistent with the template LV activation times, this may indicate effective capture of the LBB.

[0092] The IMD utilizes the surrogate LV activation time to determine whether effective capture of the LBB is occurring and adjusts one or more pacing parameters until effective LBB capture is achieved. In addition, the surrogate LV activation time may be monitored over time to ensure that continued cardiac conduction system pacing is capturing the LBB. Exemplary pacing therapy may use the surrogate LV activation time as shown in FIG. Figure 5 Delivered by the device described in.

[0093] exist Figure 6 The diagram is based on the Figure 5 An exemplary method 100 for determining effective LBB capture and LBB pacing using monitored electrical activity of a device of the invention. The method 100 may include delivering LBB pacing 102 in one or more pacing configurations. Various embodiments describing the delivery of cardiac conduction system pacing (e.g., using an IMD) are described above. When a cardiac conduction system pacing pulse is initiated, it can be described as being conducted or propagated very quickly through the cardiac conduction system and then more slowly through the ventricular myocardium before a sudden myocardial depolarization occurs.

[0094] In some embodiments where the cardiac conduction system pulses are delivered to the left bundle branch, the pacing pulses are conducted from the left bundle branch (LBB) to cause a sudden right ventricular (RV) myocardial depolarization. In such embodiments, it is also necessary to effectively capture the LBB so that a majority of the sudden RV myocardial depolarization occurs via activation of the LBB (e.g., as opposed to myocardial activation near the implanted electrode).

[0095] One or more pacing configurations may include one or more of the pacing output voltage delivered to the LBB, the number of pacing pulses, the location of the pacing electrodes, the timing between pacing pulses (otherwise referred to as the pacing rate or heart rate), atrial-ventricular (AV) delay, interventricular (VV) delay, pacing polarity, pacing pulse width, etc. Different pacing configurations may provide pacing therapy (e.g., CRT) that effectively captures the LBB, which may result in improved stroke volume and cardiac output.

[0096] In response to or during the delivery of LBB pacing 102 with one or more pacing configurations, the method 100 may also include monitoring electrical activity in the heart 104. Monitoring electrical activity in the heart may include monitoring near-field electrical signals or far-field electrical signals using the systems and devices described above. For example, as described above, monitoring of electrical activity may be accomplished using a sensing module 86. The electrical activity may include near-field or far-field electrogram (EGM) signals sensed from at least one implanted electrode. In one or more embodiments, electrical activity may be monitored in the right ventricle (RV) of the heart. In alternative embodiments, electrical activity may be monitored in another chamber or elsewhere in, on, or around the heart (such as the LBB, left or right ventricular septum, etc.). The sensing module 86 or other sensing device may monitor electrical activity (e.g., EGM signals) during the delivery 102 of LBB pacing.

[0097] In one embodiment, monitoring electrical activity may include using Figures 1 to 5 One or more implanted electrodes discussed, such as a tip electrode to a RV coil electrode monopolar EGM, a tip electrode to a shell electrode monopolar EGM, an RV coil electrode to a shell electrode monopolar EGM, and an atrial ring electrode to a shell electrode monopolar EGM. The tip electrode can be an electrode located at the tip of any lead as described above. The coil electrode can be an electrode formed in or on a coil and positioned along the lead body near the tip of the lead. The ring electrode can be an electrode formed in a ring around the lead body and positioned along the lead body near the tip of the lead. The shell electrode can be an electrode located in or around the shell of the IMD. Location identifiers such as the RV are examples of possible electrode locations. For example, the "atrial" location can be an atrium in any atrium. In an alternative embodiment, a bipolar EGM signal can be monitored.

[0098] In one embodiment, and as described above, an RV monopolar electrode (e.g., an RV tip to a monopolar implanted electrode) can be used to monitor RV electrical activity. The RV monopolar electrode can generate an EGM signal 104B, such as Figure 7 As illustrated and labeled in FIG. 1 , the EGM signal also includes an exemplary ECG 104A over the same time period, illustrating Figure 6The monitored electrical activity of method 100. More specifically, Figure 7 An ECG signal 104A is illustrated, which may be generated using one or more surface electrodes (e.g., a standard 12-lead ECG) including electrodes positioned on the surface of the patient near or at standard I, II, III, IV, V, and VI chest leads and / or upper right and left arm and lower right and left leg limb leads. More specifically, the ECG signal 104A may be an ECG signal obtained from a V5 (referred to above as V) standard surface electrode lead using a standard 12-lead ECG.

[0099] In one embodiment, the EGM signal 104B may be any EGM signal obtained from any electrode. In another embodiment, the EGM signal 104B may be an average EGM signal obtained from more than one electrode. In another embodiment, the EGM signal 104B is obtained from the RV monopolar electrode. Figure 7 Also illustrated and labeled is a signal designated 104C, which corresponds to a calculated difference signal based on the EGM signal 104B. The difference signal illustrates the rate of change of the original signal over time.

[0100] The ECG signal 104A is used to illustrate the LV activation time ("LVAT") 109 on a typical QRS waveform. Various electrodes as discussed herein can be used to define the LVAT 109. The LVAT 109 is the time interval from the delivery of a pacing pulse (corresponding to the pacing spike on the ECG signal 104A) to the peak of the R wave. As shown, the LVAT 109 is identified in the ECG signal 104A from the delivery of a pacing pulse 204 to the peak of the R wave 206.

[0101] The method 100 may also include 106: determining an alternative LV activation time 107 based on the monitored electrical activity for each of the one or more pacing configurations. The alternative LV activation time represents the LVAT. In one embodiment, the alternative LV activation time 107 is illustrated using the EGM signal 104B. In another embodiment, the alternative LV activation time 107 is illustrated using the differential EGM signal 104C. For example, the alternative LV activation time 107 extends from the delivery of the pacing pulse to a reference point on the EGM 104B or on the differential EGM 104C signal, as discussed below. The reference point discussed herein can be any measurable point within the far-field electrical activity signal or its derivative (e.g., a differential signal) that corresponds to or is related to the actual LVAT. In order to determine the reference point, the devices and systems described above may use any calculation or method (such as by using a sensing module 86 as described herein, a processor 80 as described herein, etc.) to identify the reference point. Some examples of fiducial points may include one or more of the following: the beginning of the QRS morphology or any specific point therein, maximum signal amplitude, minimum signal amplitude, minimum and maximum signal slopes, the point where the monitored electrical activity crosses an isoelectric line (which may be located, for example, at 0 volts), any other monitored electrical activity signal waveform, etc. In one embodiment, the fiducial point is the QRS peak 200. In another embodiment, the fiducial point is the maximum EGM signal slope (or peak of the differential EGM signal) 202 in the review time window 105B prior to the QRS peak 200, as discussed below.

[0102] In one embodiment, the QRS peak 200 can be identified within a first time window 105A extending from the delivery of the pacing pulse to a first time point on the EGM signal. The first time window 105A can be greater than or equal to 350 ms, greater than or equal to 400 ms, greater than or equal to 450 ms, greater than or equal to 500 ms, greater than or equal to 550 ms, greater than or equal to 600 ms, etc., and / or less than or equal to 350 ms, less than or equal to 300 ms, less than or equal to 250 ms, less than or equal to 200 ms, less than or equal to 150 ms, less than or equal to 100 ms, etc. The first time window 105A can be any first time window within a selected range, such as Figure 7 In another embodiment, rather than using a time window, the first QRS peak value identified after the pacing pulse is delivered may be used as a reference point. As described above, the QRS peak value 200 may be identified in a variety of ways.

[0103] In one embodiment, as described herein, the review time window 105B can be used to identify a reference point (before the QRS peak 200) of the maximum EGM signal slope 202. The review time window 105B can be greater than or equal to 60ms, greater than or equal to 65ms, greater than or equal to 70ms, greater than or equal to 75ms, greater than or equal to 80ms, greater than or equal to 100ms, etc., and / or less than or equal to 60ms, less than or equal to 55ms, less than or equal to 50ms, less than or equal to 45ms, less than or equal to 40ms, less than or equal to 35ms, etc. The review time window 105B can be any review time window within a selected range, such as Figure 7 In another embodiment, rather than using a look-back time window, the first maximum EGM signal slope 202 identified before the initial QRS peak after the pacing pulse is delivered may be used as a reference point. The maximum EGM slope 202 may be identified in a variety of ways, as described above.

[0104] The determined surrogate LV activation time 107 value may be the time interval from the delivery of the pacing pulse to the reference point. Figure 7 As shown, in one embodiment, the reference point is the maximum EGM signal slope 202.

[0105] The method 100 may also include determining LBB capture 108 based on the determined alternative LV activation time 107 for each of the one or more pacing configurations. In one embodiment, determining LBB capture may be based on the determined alternative LV activation time 107 remaining relatively consistent for each of the one or more pacing configurations. Similar to determining LBB capture based on a typical ECG and a typical LV activation time remaining constant and short, as discussed herein, the EGM signal and the alternative LV activation 107 time may be used to determine LBB capture.

[0106] The relative consistency of the alternative LV activation times 107 with one or more pacing configurations can be any selected or set defined consistency. For example, consistency can be defined as maintaining the alternative LV activation time 107 with one pacing configuration (of the one or more pacing configurations) within about 9% of the alternative LV activation time 107 with a previous pacing configuration (e.g., the pacing configuration used just before, or another pacing configuration used before that). In other embodiments, consistency as defined can maintain the alternative LV activation time 107 with the previous pacing configuration within about 5%, or about 10%, or about 15%, or about 20%, or about 25%, or about 30%, or about 35%, or about 40%, or about 50%, or about 60%, or about 70%, or about 80%, or about 90%. In another embodiment, consistency can be defined according to a ratio relative to a percentage, or can be defined according to a set alternative LV activation time value or threshold. In another embodiment, consistency can be any consistency within a selected range.

[0107] In another embodiment, the relative consistency of the surrogate LV activation times 107 with one or more pacing configurations may be defined as such that the surrogate LV activation time 107 at one paced heartbeat with one pacing configuration is within about 9% of the surrogate LV activation time 107 at a previous paced heartbeat (e.g., the immediately previous heartbeat, or another previous heartbeat) with the same pacing configuration. In other embodiments, the consistency as defined may be maintained within about 5%, or about 10%, or about 15%, or about 20%, or about 25%, or about 30%, or about 35%, or about 40%, or about 50%, or about 60%, or about 70%, or about 80%, or about 90% of the surrogate LV activation time 107 at the previous paced heartbeat. In another embodiment, the consistency may be defined in terms of a ratio relative to a percentage, or may be defined in terms of a set surrogate LV activation time value or threshold. Further, for example, the consistency may be any consistency within a selected range.

[0108] In another embodiment, the surrogate LV activation time 107 may be compared to a template or threshold surrogate LV activation time 107A (in Fig.10 and Fig.11107A). For example, the threshold surrogate LV activation time may be determined based on the electrical activity of the template paced heartbeat. If the surrogate LV activation time 107 is within about 9% of the threshold surrogate LV activation time 107A, the comparison of the surrogate LV activation time 107 with the threshold surrogate LV activation time 107A may indicate effective capture of the LBB. In other embodiments, the consistency as defined may be maintained within, for example, about 5%, or about 10%, or about 15%, or about 20%, or about 25%, or about 30%, or about 35%, or about 40%, or about 50%, or about 60%, or about 70%, or about 80%, or about 90% of the threshold surrogate LV activation time 107A. In another embodiment, the comparison may be defined in terms of a ratio rather than a percentage. For example, the consistency may be any consistency within a selected range. In further embodiments, effective capture of the LBB may be determined using any device, system, or method known to one of ordinary skill in the art.

[0109] After determining LBB capture 108 for one or more pacing configurations, the method 100 may further include selecting a pacing configuration 110 based on the determined alternative LV activation times. In one embodiment, where the determined alternative LV activation times 107 are used to determine LBB capture with one of the one or more pacing configurations, such pacing configuration that causes LBB capture may be beneficially used as the selected pacing configuration for the patient, and thus be selected. Furthermore, where various determined alternative LV activation times 107 cause effective LBB capture with more than one of the one or more pacing configurations, then one of the pacing configurations may be selected based on various criteria to serve as the selected pacing configuration for the patient. For example, a lower pacing output may result in less energy usage and longer device (e.g., using an IMD) battery life, and thus, if more than one pacing configuration causes effective LBB capture, then a pacing configuration that uses less energy and causes longer device battery life may be selected.

[0110] The method 100 may also include delivering LBB pacing in the selected pacing configuration 112. Various embodiments describing the delivery of cardiac conduction system pacing (e.g., using an IMD) are described above. In addition, the method 100 may be performed more than once, such that a medical provider or user may periodically recheck valid LBB capture based on an alternate LV activation time 107, change pacing configuration settings, monitor valid capture of the LBB, etc.

[0111] Figure 8 This is an example of using Figure 6Scatter plot of the correlation between the surrogate LV activation time 107 determined by the method and the actual LVAT 109. The illustrated data was captured from eight patients at different pacing outputs, and each illustrated data point indicates a representative heartbeat from one patient at one pacing output. The example pacing outputs vary between approximately 0.5 volts to approximately 2 volts per pacing pulse. In one or more embodiments, the pacing output may be less than or equal to 0.5V, 1V, 1.25V, 1.5V, 1.75V, 2V, 3V, 4V, 5V, 6V, etc. The pacing output may be greater than or equal to 0.5V, 1V, 2V, 2.25V, 2.5V, 3V, 4V, 5V, 6V, etc. More specifically, Figure 8 The correlation between the surrogate LV activation time 107 and the LVAT 109 based on the time interval from the delivery of the pacing pulse corresponding to the reference point maximum EGM signal slope 202 is illustrated. The LVAT 109 can be correlated with the LVAT 109 using the following formula: Figure 8 The alternative LV activation time 107 shown is related to and makes R 2 Value>0.95. Therefore, there is a high correlation between conventional LVAT 109 and surrogate LV activation time 107 based on reference point 202, indicating that surrogate LV activation time 107 may be used clinically similar to conventional LVAT 109.

[0112] LVAT = (0.92) * (alternative LV activation time based on 202)

[0113] Fig. 9 FIG. 1 is another depiction of an exemplary ECG signal 104A and an exemplary EGM signal 104B and an exemplary differential EGM signal 104C over time, illustrating a method of performing an operation according to one or more embodiments. Figure 6 The method 100 of monitoring electrical activity. Fig. 9 As shown above, Figure 7 The same signals described are used herein, and the same exemplary LVAT 109 is also illustrated. Fig. 9 Also illustrated with Figure 7 The first time window 105A may be the same as the QRS peak 200 of the possible reference point depicted in FIG. Figure 7 Same as described. On the contrary, Fig. 9 The example is based on extending from the delivery of the pacing pulse to the reference point QRS peak 200 (rather than the reference point of the maximum EGM signal slope 202, as discussed above and as shown in Figure 7 The determined surrogate LV activation time 107 value may be the time interval from the delivery of the pacing pulse to the reference point. Fig. 9 As shown, in one embodiment, the reference point is the maximum EGM QRS peak 200.

[0114] Fig.10 is an example Figure 6 A scatter plot of the correlation between another different determined surrogate LV activation time 107 and the actual LVAT 109 of method 100. Figure 8 The illustrated data is captured from eight patients at different pacing outputs, and each illustrated data point indicates a representative heartbeat from one patient at one pacing output. More specifically, Fig.10 The correlation between the surrogate LV activation time 107 and the LVAT 109 based on the time interval from the delivery of the pacing pulse to the reference point QRS peak 200 is illustrated. The LVAT 109 can be related to the surrogate LV activation time 107 using the following formula, and R 2 Value>0.95. Therefore, there is a high correlation between conventional LVAT 109 and surrogate LV activation time 107 based on reference point 200, indicating that surrogate LV activation time 107 can be used clinically similar to conventional LVAT 109.

[0115] LVAT = (0.62) * (alternative LV activation time based on 200)

[0116] Fig.11 It can be used from Figure 2 to Figure 5 The device utilizes the EGM signal and uses Figure 6 , Figure 7 and Fig. 9 A block diagram of another exemplary method 300 for determining LBB capture using one or more processes that are the same or similar to the method shown. Fig.11 The method 300 may be applied during a capture threshold test at implantation and tracked with a programmer. The capture threshold test may be used to determine the lowest pacing output voltage that still results in effective capture of the LBB and effective pacing of the LBB (as opposed to, for example, ineffective capture or pacing of the LBB, but rather capture or pacing of the ventricular myocardium, such as LV septal pacing, etc.). Such a capture threshold test method may include the steps of initiating a capture threshold test 301, delivering a test pacing pulse 302 in one of one or more test pacing configurations, and determining whether there is a loss of ventricular capture (e.g., Fig.11 In response to determining that there is a loss of ventricular capture, the capture threshold testing method may further include recording such determination that there is no ventricular capture in a report and continuing testing 308.

[0117] In response to determining that ventricular capture is still present, the capture threshold test method may further include determining the slope 202 from the test pacing pulse to the maximum EGM signal (at Fig.11310). The determined time interval may alternatively be the time interval from the test pacing pulse to the QRS peak 200, as described above. The method may also include comparing the determined time with a time determined for a previous test pacing pulse 312. The method may also include determining whether the comparison is within a first threshold 314. In response to a determination that the comparison is not within the first threshold, such a determination is associated with a non-valid LBB capture, and the method may also include issuing a warning message 316. In response to a determination that the comparison is within the first threshold, such a determination is associated with a valid LBB capture, and the method may also include comparing the determined time with a template time 318 (specified using a dashed line and a "template" designation 320). Template 320 may be equivalent to template threshold 107A discussed above.

[0118] The method may also include determining that the threshold comparison is within a second threshold 322. In response to a determination that the comparison is not within the second threshold, such determination is associated with non-valid LBB capture, and the method may also include issuing a warning message 324. In response to a determination that the comparison is within the second threshold, such determination is associated with valid LBB capture, and the method may also include determining whether the last test pace has been delivered 326. In response to a determination that the last test pace has not been delivered, the method may return to step 302 of delivering a test pacing pulse in one of the one or more test pacing configurations. In response to a determination that the last test pace has been delivered, the method may complete the capture threshold test 330. Once the method is completed, the conventional capture threshold may be recorded, reported, etc.

[0119] Fig.12 It can be used from Figure 2 to Figure 5 The device utilizes the EGM signal and uses Figure 6 , Figure 7 , Fig. 9 and Fig.11 A block diagram of another exemplary method 400 for determining LBB capture using one or more processes that are the same or similar to the method shown. Fig.12 The method 400 may be applied or integrated with capture management features as described herein, and may also be used for long-term tracking of trends in EGM-based surrogate LV activation time 107 as a monitoring feature over time.

[0120] Fig.12 Method 400 is similar to Fig.11 The method 300 does not include repetitions with various pacing configurations. Instead, Fig.12 The method 400 is not repeated and is performed only for one test pacing pulse with one pacing configuration. Based on the patient's surrogate LV activation time 107, Fig.12The results of method 400 may indicate that the patient's LBB is effectively captured or not effectively captured. If the results indicate that the patient's LBB is not effectively captured, changes in the patient's surrogate LV activation time 107 may be monitored over time, and in some cases, the surrogate LV activation time first threshold and second threshold (described below) may be changed or updated.

[0121] Method 400 may include the steps of checking device status 401, delivering a test pacing pulse in one of one or more test pacing configurations 402, and determining whether there is a loss of ventricular capture (e.g., Fig.12 In response to determining that there is a loss of ventricular capture, the capture threshold test method may further include completing the test and reporting the results 408 .

[0122] In response to determining that ventricular capture is still present, the capture threshold test method may further include determining the slope 202 from the test pacing pulse to the maximum EGM signal (at Fig.12 410). The determined time interval may alternatively be the time interval from the test pacing pulse to the QRS peak 200, as described above. The method may also include comparing the determined time with a time determined for a previous test pacing pulse 412. The method may also include determining whether the comparison is within a first threshold 414. In response to a determination that the comparison is not within the first threshold, such a determination is associated with a non-valid LBB capture, and the method may also include issuing a warning message 416. In response to a determination that the comparison is within the first threshold, such a determination is associated with a valid LBB capture, and the method may also include comparing the determined time with a template time 418 (specified using a dashed line and a "template" designation 420). Template 420 may be equivalent to the template threshold 107A discussed above.

[0123] The method may also include determining that the threshold comparison is within a second threshold 422. Responsive to a determination that the comparison is not within the second threshold, such determination is associated with non-valid LBB capture, and the method may also include issuing a warning message 424. Responsive to a determination that the comparison is within the second threshold, such determination is associated with valid LBB capture, and the method may complete the test 426. Once the method is completed, the surrogate LV activation time 107 or valid capture of the patient's LBB may be recorded, reported, etc.

[0124] Fig.13 This is an example of using Figure 6109 and the scatter plot of the correlation between the determined surrogate LV activation time 107 and the actual LVAT 109 of the method and the reference point 202. The illustrated data was captured from one patient and at different pacing outputs. The example pacing outputs varied between about .75 volts and about 5 volts per pacing pulse. In one or more embodiments, the pacing outputs may be as described herein with respect to Figure 8 More specifically, Fig.13 The correlation between the surrogate LV activation time 107 and the LVAT 109 based on the time interval from the delivery of the pacing pulse corresponding to the reference point maximum EGM signal slope 202 at different pacing outputs is illustrated. The aggregated data all appear similar, as shown by the dashed ellipse around the aggregated data. Such similarity at various pacing outputs indicates that the surrogate LV activation time 107 does not change with the pacing output. This indication, in turn, indicates that the LBB is effectively captured because the surrogate LV activation time 107 and the LVAT 109 remain constant at various pacing outputs.

[0125] Fig.14 This is an example of using Figure 6 A scatter plot of the correlation between the determined surrogate LV activation time 107 and the actual LVAT 109 of the method and the reference point 202 is similar to Fig.13 , but from a different patient and as described above Fig.13 In one or more embodiments, the pacing output may be as described herein. Figure 8 As stated. Fig.14 As shown, the data does not all look similar, as shown by the dashed circles around the different groups of aggregated data. Such differences at various pacing outputs indicate that the surrogate LV activation time 107 varies with the pacing output. This indication, in turn, indicates that the LBB is not being effectively captured at least at some of the pacing outputs because the surrogate LV activation time 107 and LVAT 109 do not remain constant at the various pacing outputs. For example, a prolonged LVAT 109 or prolonged surrogate LV activation time 107 may indicate undesirable LV septal pacing and ineffective LBB capture. In one or more embodiments, as shown in FIG. Fig.13 and Fig.14 Such aggregate data as shown may be useful to medical providers as another method of determining effective capture of LBB in a patient.

[0126] Various examples have been described. These and other examples are within the scope of the appended claims. For example, the illustrative methods described herein may be implemented using a single-chamber, dual-chamber, or triple-chamber pacemaker (e.g., CRT-P) or ICD (e.g., CRT-D) device.

[0127] Illustrative Embodiments

[0128] Although the present disclosure is not limited thereto, an understanding of various aspects of the present disclosure will be gained through a discussion of the specific exemplary embodiments provided below. Various modifications to the exemplary embodiments as well as additional embodiments of the present disclosure will become apparent herein.

[0129] Embodiment Ex1: An implantable medical device, comprising:

[0130] one or more implantable electrodes, the one or more implantable electrodes comprising a left bundle branch (LBB) electrode positionable proximate a portion of a left bundle branch of the patient; and

[0131] A computing device comprising processing circuitry and operably coupled to the one or more implantable electrodes, wherein the computing device is configured to:

[0132] delivering LBB pacing proximate to the LBB using the LBB electrode in one or more pacing configurations;

[0133] monitoring electrical activity using the one or more implanted electrodes during delivery of the LBB pacing in the one or more pacing configurations;

[0134] determining a substitute LV activation time based on the monitored electrical activity for each of the one or more pacing configurations, wherein the substitute LV activation time is representative of the LV activation time; and

[0135] A determination is made as to whether the LBB pacing has captured the LBB for each of the one or more pacing configurations based on the determined alternative LV activation time for each of the one or more pacing configurations.

[0136] Embodiment Ex2: A method, comprising:

[0137] delivering LBB pacing proximate a portion of a left bundle branch (LBB) of a patient using an LBB electrode positioned proximate the LBB in one or more pacing configurations;

[0138] monitoring electrical activity using one or more electrodes during delivery of said LBB pacing in said one or more pacing configurations;

[0139] determining a substitute LV activation time based on the monitored electrical activity for each of the one or more pacing configurations, wherein the substitute LV activation time is representative of the LV activation time; and

[0140] A determination is made as to whether the LBB pacing has captured the LBB for each of the one or more pacing configurations based on the determined alternative LV activation time for each of the one or more pacing configurations.

[0141] Embodiment Ex3: An implantable medical device according to Embodiment Ex1 or a method according to Embodiment Ex2, wherein the one or more implantable electrodes further include an RV electrode proximate to a portion of the patient's right ventricle (RV), and wherein monitoring electrical activity using the one or more electrodes during delivery of the LBB pacing with the one or more pacing configurations includes monitoring electrical activity using the RV electrode proximate to the RV.

[0142] Embodiment Ex4: An implantable medical device according to Embodiment Ex1 or a method according to Embodiment Ex2, wherein monitoring electrical activity using the one or more electrodes during delivery of the LBB pacing in the one or more pacing configurations comprises monitoring electrical activity using the LBB electrodes proximate to the LBB.

[0143] Embodiment Ex5: An implantable medical device or method according to any one of Embodiments Ex1 to Ex4, wherein the one or more pacing configurations comprises a plurality of pacing configurations,

[0144] The computing device is further configured to perform the following operations, or the method further includes:

[0145] selecting a pacing configuration from the plurality of pacing configurations based on the alternative LV activation time for each of the plurality of pacing configurations and a pacing setting for each of the plurality of pacing configurations; and

[0146] LBB pacing is delivered in the selected pacing configuration.

[0147] Embodiment Ex6: The implantable medical device or method of Embodiment Ex5, wherein selecting a pacing configuration from among the plurality of pacing configurations based on the alternative LV activation time for each of the plurality of pacing configurations and the pacing setting for each of the plurality of pacing configurations further comprises:

[0148] selecting one or more additional pacing configurations of the plurality of pacing configurations, wherein the one or more additional pacing configurations are each determined to capture the LBB based on the determined alternate LV activation time; and

[0149] Selecting one of the one or more additional pacing configurations in the plurality of pacing configurations, wherein the one pacing configuration comprises a lowest pacing output of the one or more additional pacing configurations, and wherein the one pacing configuration is the selected pacing configuration.

[0150] Embodiment Ex7: An implantable medical device or method according to any one of Embodiments Ex1 to Ex6, wherein the alternative LV activation time extends between a delivered LBB pacing pulse of LBB pacing and a reference point within the monitored electrical activity.

[0151] Embodiment Ex8: An implantable medical device or method according to embodiment Ex7, wherein the reference point is the maximum slope of the activity monitored within a review time window, wherein the review time window precedes the maximum peak of the electrical activity monitored within the post-pacing time window after the LBB pacing pulse.

[0152] Embodiment Ex9: An implantable medical device or method according to embodiment Ex8, wherein the review time window is less than or equal to 75 milliseconds (ms), and the post-pacing time window is less than or equal to 350 ms.

[0153] Embodiment Ex10: An implantable medical device or method according to embodiment Ex7, wherein the reference point is the maximum peak value of the activity monitored within the post-pacing time window after the LBB pacing pulse.

[0154] Embodiment Ex11: An implantable medical device or method according to Embodiment Ex10, wherein the post-pacing time window is less than or equal to 350 ms.

[0155] Embodiment Ex12: An implantable medical device or method according to any one of Embodiments Ex1 to Ex11, wherein determining whether the LBB pacing has captured the LBB for each of the one or more pacing configurations includes: determining that the LBB pacing has captured the LBB when the alternative LV activation time is within a selected percentage of one or more alternative LV activation times, the selected percentage being determined based on electrical activity monitored during delivery of LBB pacing using other pacing configurations in the one or more pacing configurations.

[0156] Embodiment Ex13: An implantable medical device or method according to embodiment Ex12, wherein the selected percentage is 20%.

[0157] Embodiment Ex14: An implantable medical device or method according to any one of Embodiments Ex12 to Ex13, wherein the one or more alternative LV activation times determined using the other pacing configurations in the one or more pacing configurations include previously determined alternative LV activation times, and the previously determined alternative LV activation times are determined based on electrical activity monitored during delivery of LBB pacing using the most recently used pacing configuration.

[0158] Embodiment Ex15: An implantable medical device or method according to any one of Embodiments Ex1 to Ex11, wherein determining whether the LBB pacing has captured the LBB for each of the one or more pacing configurations includes: determining that the LBB pacing has captured the LBB when the determined alternative LV activation time is within a selected percentage of a threshold alternative LV activation time.

[0159] Embodiment Ex16: An implantable medical device or method according to embodiment Ex15, wherein the threshold alternative LV activation time is determined based on the electrical activity of the template paced heartbeat.

[0160] Embodiment Ex17: An implantable medical device or method according to any one of Embodiments Ex15 to Ex16, wherein the selected percentage is 20%.

[0161] Embodiment Ex18: An implantable medical device or method according to any one of Embodiments Ex1 to Ex11, wherein determining whether the LBB pacing has captured the LBB for each of the one or more pacing configurations includes: determining that the LBB pacing has captured the LBB when the alternative LV activation time is within a selected percentage of one or more alternative LV activation times, the selected percentage being determined based on electrical activity monitored during delivery of LBB pacing using the same pacing configuration in the one or more pacing configurations.

[0162] Embodiment Ex19: An implantable medical device or method according to embodiment Ex18, wherein the selected percentage is 20%.

[0163] Embodiment Ex20: An implantable medical device or method according to any one of Embodiments Ex18 to Ex19, wherein the one or more alternative LV activation times determined using the same pacing configuration in the one or more pacing configurations include a previously determined alternative LV activation time, wherein the previously determined alternative LV activation time is determined based on electrical activity monitored during LBB pacing delivered using the most recent heartbeat.

[0164] The present disclosure has been provided with reference to exemplary embodiments and examples, and is not meant to be interpreted in a limiting sense. As previously mentioned, those skilled in the art will recognize that various other exemplary applications can utilize the beneficial properties of the apparatus and methods described herein using the techniques as described herein. Various modifications of the exemplary embodiments and examples will become apparent after reference to this specification.

[0165] In one or more examples, the described techniques can be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, the functions can be stored as one or more instructions or codes on a computer-readable medium and executed by a hardware-based processing unit. The computer-readable medium may include a non-transitory computer-readable medium that corresponds to a tangible medium, such as a data storage medium (e.g., RAM, ROM, EEPROM, flash memory, or any other medium that can be used to store desired program code in the form of instructions or data structures and can be accessed by a computer).

[0166] 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 circuits. Thus, the term "processor" as used herein may refer to any of the aforementioned structures or any other physical structure suitable for implementing the described techniques. Additionally, these techniques may be fully implemented in one or more circuits or logic elements.

[0167] All references and publications cited herein are expressly incorporated by reference in their entirety for all purposes unless in any respect directly contradictory to this disclosure.

[0168] Unless otherwise specified, all scientific and technical terms used herein have the meanings commonly used in the art. The definitions provided herein are intended to facilitate understanding of certain terms frequently used herein and are not intended to limit the scope of the present disclosure.

[0169] Unless otherwise indicated, all numerical values ​​expressing feature sizes, amounts, and physical properties used in the specification and claims may be understood to be modified by the terms "exactly" or "about." Therefore, unless otherwise indicated, the numerical parameters set forth in the foregoing specification and the appended claims are approximations that may vary depending upon the desired properties sought to be obtained by one skilled in the art utilizing the teachings disclosed herein or, for example, within typical ranges of experimental error.

[0170] The recitation of numerical ranges by endpoints includes all values ​​within the range (e.g., 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, and 5) and any range within the range. As used herein, the term "at most" or "not greater than" a value (e.g., at most 50) includes that value (e.g., 50), and the term "not less than" a value (e.g., not less than 5) includes that value (e.g., 5).

[0171] The terms "coupled" or "connected" refer to elements being directly attached to one another (being in direct contact with one another) or indirectly attached (having one or more elements between and attaching two elements). Both terms may be modified by the interchangeable use of "operably" and "operably capable of operating" to describe a connection or connection configured to allow the components to interact to perform at least some functions (e.g., a mobile user device may be operatively coupled to a cellular network to send data to or receive data from it).

[0172] References to "one embodiment," "an embodiment," "certain embodiments," or "some embodiments," etc., mean that a particular feature, configuration, composition, or characteristic described in conjunction with the embodiment is included in at least one embodiment of the present disclosure. Thus, the appearance of such phrases in various places throughout the text are not necessarily referring to the same embodiment of the present disclosure. Furthermore, the particular features, configurations, compositions, or characteristics may be combined in any suitable manner in one or more embodiments.

[0173] As used in this specification and the appended claims, the singular forms "a / an", and "the" encompass embodiments having plural referents, unless the content clearly dictates otherwise. As used in this specification and the appended claims, the term "or" is generally used in its sense, including "and / or", unless the context clearly dictates otherwise.

[0174] As used herein, "having", "including", "comprising", etc. are used in their open-ended sense and generally mean "including but not limited to". It should be understood that "consisting essentially of", "consisting of", etc. are subsumed under "comprising", etc.

[0175] The term "and / or" means one or all of the listed elements or a combination of at least two of the listed elements.

[0176] The phrases "at least one of," "including at least one of," and "one or more of" accompanying a list refer to any one of the items in the list and any combination of two or more items in the list.

Claims

1. An implantable medical device, comprising: one or more implantable electrodes, the one or more implantable electrodes comprising a left bundle branch (LBB) electrode positionable proximate a portion of a left bundle branch of the patient; and A computing device comprising processing circuitry and operably coupled to the one or more implantable electrodes, wherein the computing device is configured to: delivering LBB pacing proximate to the LBB using the LBB electrode in one or more pacing configurations; monitoring electrical activity using the one or more implanted electrodes during delivery of the LBB pacing in the one or more pacing configurations; determining a substitute LV activation time based on the monitored electrical activity for each of the one or more pacing configurations, wherein the substitute LV activation time represents a LV activation time; as well as A determination is made as to whether the LBB pacing has captured the LBB for each of the one or more pacing configurations based on the determined alternative LV activation time for each of the one or more pacing configurations.

2. A method comprising: delivering LBB pacing proximate a portion of a left bundle branch (LBB) of a patient using an LBB electrode positioned proximate the LBB in one or more pacing configurations; monitoring electrical activity using one or more electrodes during delivery of said LBB pacing in said one or more pacing configurations; determining a substitute LV activation time based on the monitored electrical activity for each of the one or more pacing configurations, wherein the substitute LV activation time represents a LV activation time; as well as A determination is made as to whether the LBB pacing has captured the LBB for each of the one or more pacing configurations based on the determined alternative LV activation time for each of the one or more pacing configurations.

3. An implantable medical device according to claim 1 or a method according to claim 2, wherein the one or more implantable electrodes further include an RV electrode proximate to a portion of the patient's right ventricle (RV), and wherein monitoring electrical activity using the one or more electrodes during delivery of the LBB pacing in the one or more pacing configurations includes monitoring electrical activity using the RV electrode proximate to the RV.

4. An implantable medical device according to claim 1 or a method according to claim 2, wherein monitoring electrical activity using the one or more electrodes during delivery of the LBB pacing in the one or more pacing configurations comprises monitoring electrical activity using the LBB electrodes proximate to the LBB.

5. An implantable medical device or method according to any one of claims 1 to 4, wherein the one or more pacing configurations comprises a plurality of pacing configurations, The computing device is further configured to perform the following operations, or the method further includes: selecting a pacing configuration from the plurality of pacing configurations based on the alternative LV activation time for each of the plurality of pacing configurations and a pacing setting for each of the plurality of pacing configurations; as well as LBB pacing is delivered in the selected pacing configuration.

6. The implantable medical device or method of claim 5, wherein selecting a pacing configuration of the plurality of pacing configurations based on the alternative LV activation time for each of the plurality of pacing configurations and the pacing settings for each of the plurality of pacing configurations further comprises: selecting one or more additional pacing configurations of the plurality of pacing configurations, wherein the one or more additional pacing configurations are each determined to capture the LBB based on the determined alternate LV activation time; and Selecting one of the one or more additional pacing configurations in the plurality of pacing configurations, wherein the one pacing configuration comprises a lowest pacing output of the one or more additional pacing configurations, and wherein the one pacing configuration is the selected pacing configuration.

7. An implantable medical device or method according to any one of claims 1 to 5, wherein the alternative LV activation time extends between a delivered LBB paced LBB pacing pulse and a reference point within the monitored electrical activity.

8. An implantable medical device or method according to claim 7, wherein the reference point is the maximum slope of activity monitored within a look-back time window, wherein the look-back time window precedes the maximum peak of electrical activity monitored within a post-pacing time window after the LBB pacing pulse.

9. The implantable medical device or method of claim 8, wherein the look-back time window is less than or equal to 75 milliseconds (ms) and the post-pacing time window is less than or equal to 350 ms.

10. The implantable medical device or method of claim 7, wherein the reference point is a maximum peak of activity monitored within a post-pacing time window following the LBB pacing pulse.

11. The implantable medical device or method of claim 10, wherein the post-pacing time window is less than or equal to 350 ms.

12. The implantable medical device or method of any one of claims 1 to 5, wherein determining whether the LBB pacing has captured the LBB for each of the one or more pacing configurations comprises: The LBB pacing is determined to have captured the LBB when the alternative LV activation time is within a selected percentage of one or more alternative LV activation times, the selected percentage being determined based on electrical activity monitored during delivery of LBB pacing using other pacing configurations among the one or more pacing configurations.

13. The implantable medical device or method of claim 12, wherein the selected percentage is 20%.

14. An implantable medical device or method according to claim 12, wherein the one or more alternative LV activation times determined using the other pacing configurations among the multiple pacing configurations include previously determined alternative LV activation times, and the previously determined alternative LV activation times are determined based on electrical activity monitored during delivery of LBB pacing using the most recently used pacing configuration.

15. The implantable medical device or method of any one of claims 1 to 5, wherein determining whether the LBB pacing has captured the LBB for each of the one or more pacing configurations comprises: In a case where the determined surrogate LV activation time is within a selected percentage of a threshold surrogate LV activation time, it is determined that the LBB pacing has captured the LBB.

16. The implantable medical device or method of claim 15, wherein the threshold surrogate LV activation time is determined based on the electrical activity of a template paced heartbeat.

17. The implantable medical device or method of claim 15, wherein the selected percentage is 20%.

18. The implantable medical device or method of any one of claims 1 to 5, wherein determining whether the LBB pacing has captured the LBB for each of the one or more pacing configurations comprises: The LBB pacing is determined to have captured the LBB when the alternative LV activation time is within a selected percentage of one or more alternative LV activation times, the selected percentage being determined based on electrical activity monitored during delivery of LBB pacing using the same pacing configuration among the one or more pacing configurations.

19. The implantable medical device or method of claim 18, wherein the selected percentage is 20%.

20. An implantable medical device or method according to claim 18, wherein the one or more alternative LV activation times determined using the same pacing configuration in the one or more pacing configurations include previously determined alternative LV activation times, and the previously determined alternative LV activation times are determined based on electrical activity monitored during LBB pacing delivered using a most recent heartbeat.

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