Advanced pacing delay during atrial fibrillation

Abstract

The present disclosure relates generally to pacing of a cardiac conduction system and / or to a patient's left ventricular septum, and more particularly to providing cardiac conduction system and / or left ventricular septum pacing according to an advanced pacing delay during atrial fibrillation. The advanced pacing delay may be determined in various ways during or not during atrial fibrillation.

Description

[0001] This application claims the benefit of U.S. Provisional Patent Application Serial No. 63 / 393,072, filed on July 28, 2022, the entire contents of which are incorporated herein by reference. Technical Field

[0002] The present disclosure generally relates to determining and using advance pacing delays during atrial fibrillation, for example, to ensure capture of the left ventricle.

[0003] 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.

[0004] Over time, the left ventricle can become very inefficient at 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, fifty percent of heart failure patients have a life expectancy of five years. Another possible cause of heart failure is due to atrial fibrillation, which is an irregular and often very rapid heart rhythm or arrhythmia. During atrial fibrillation, the atria of the heart may beat out of sync with the ventricles of the heart due to the arrhythmia of the atria, and this may cause blood clots in the heart and increase the risk of, for example, 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).

[0005] 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 is a delay between atrial contraction and ventricular contraction, which 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.

[0006] 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

[0007] The present disclosure as a whole relates to pacing the heart using, for example, cardiac conduction system pacing, left ventricular septal pacing, etc., using an IMD that uses an advance pacing delay and / or a selected pacing rate during atrial fibrillation. The left ventricle (LV) may not be effectively captured during atrial fibrillation because, for example, chaotic activation timing caused by atrial fibrillation may depolarize the ventricle before a pacing pulse can be delivered. The advance pacing delay represents a time period or time period delay from the delivery of a pacing pulse (e.g., a left bundle branch pulse) to a ventricular event (e.g., ventricular myocardial depolarization). Using the advance pacing delay, the IMD can effectively capture and pace the LV during atrial fibrillation. Such effective LV capture may be desirable for patients undergoing cardiac resynchronization therapy (CRT).

[0008] Specifically, exemplary devices and methods are described herein to provide therapeutic pacing that effectively captures the LV during atrial fibrillation. For example, effective capture of such LV can be accomplished by pacing the cardiac conduction system, or can be accomplished by pacing the left ventricular septal tissue. The paced cardiac conduction system may include pacing, for example, a His-Purkinje system, including a left bundle branch, a right bundle branch, or a His bundle. Specifically, exemplary devices and methods are described herein to provide a cardiac conduction system pacing therapy that can effectively capture and pace the LV by effectively capturing the left bundle branch (LBB) of the cardiac conduction system. Such cardiac conduction system pacing therapy can determine and adjust an advance pacing delay based on a near-field signal or a far-field signal so as to be able to provide effective cardiac therapy to a patient during atrial fibrillation.

[0009] In one or more embodiments, exemplary devices and methods are described herein to provide left ventricular septal pacing (LVSP) that can effectively capture and pace the LV. Such LVSP therapy can determine and adjust advance pacing delays based on near-field signals or far-field signals so as to provide effective cardiac therapy to patients during atrial fibrillation.

[0010] Exemplary devices and methods may be described as employing at least a single chamber device solution for patients indicated for cardiac resynchronization therapy, which solution may include one or more of a standard right atrial lead, a 3830 or 3830D lead for pacing the cardiac conduction system, and a left ventricular lead.

[0011] An exemplary implantable medical device may include one or more implantable electrodes for sensing and pacing a patient's heart. The one or more implantable electrodes include a cardiac conduction system electrode that can be positioned proximate to a portion of the patient's cardiac conduction system. The device also includes a computing device that includes a processing circuit. The computing device can be operably connected to the one or more implantable electrodes. The computing device is configured to determine an advance pacing delay to capture the cardiac conduction system. The advance pacing delay represents a time period from the delivery of a cardiac conduction system pacing pulse to a ventricular event. The computing device is further configured to initiate delivery of cardiac conduction system pacing during atrial fibrillation using the cardiac conduction system electrode based on the advance pacing delay.

[0012] An exemplary implantable medical device may include one or more implantable electrodes for sensing and pacing a patient's heart, wherein the one or more implantable electrodes include an electrode that can be positioned near the left ventricle of the patient's heart. The device may also include a computing device, which includes a processing circuit. The computing device can be operably connected to the one or more implantable electrodes. The computing device is configured to determine an advance pacing delay to capture ventricular myocardium. The advance pacing delay represents a time period from the delivery of an LV septal pacing pulse to a ventricular event. The computing device is further configured to initiate the delivery of LV septal pacing during atrial fibrillation using the electrodes according to the advance pacing delay. In order to determine the advance pacing delay, the computing device is further configured to initiate the delivery of a test LV septal pacing during atrial fibrillation to capture the ventricular myocardium according to one or more parameters. The one or more parameters include an AV delay that is shorter than an intrinsic atrioventricular (AV) delay. The computing device is further configured to monitor a far-field electrogram using at least one of the one or more implantable electrodes and the one or more surface electrodes during the test LV septal pacing. The computing device is further configured to determine a reference point within the far-field electrogram. The computing device is further configured to determine an advance pacing delay based on a reference point. The advance pacing delay is a delay period from the delivery of a test LV septal pacing pulse of a test LV septal pacing to a reference point. The reference point is a maximum negative QRS deflection identified within a far-field electrogram.

[0013] An exemplary method may include determining an advance pacing delay to capture a cardiac conduction system of a patient. The advance pacing delay represents a time period from delivery of a cardiac conduction system pacing pulse to a ventricular event. The method may also include delivering cardiac conduction system pacing during atrial fibrillation using a cardiac conduction system electrode positioned proximate to a portion of the patient's cardiac conduction system based on the advance pacing delay.

[0014] An exemplary method may include determining an advance pacing delay to capture a patient's left ventricle. The advance pacing delay represents a time period from the delivery of a pacing pulse to a ventricular event. The method may include delivering LV septal pacing during atrial fibrillation using an electrode positioned proximate to the left ventricle of the patient's heart according to the advance pacing delay. Determining the advance pacing delay also includes delivering a test LV septal pacing during atrial fibrillation to capture the ventricular myocardium according to one or more parameters. The one or more parameters include an AV delay that is shorter than an intrinsic atrioventricular (AV) delay. Determining the advance pacing delay also includes monitoring a far-field electrogram using at least one of one or more implanted electrodes and one or more surface electrodes during the test LV septal pacing. Determining the advance pacing delay also includes determining a reference point within the far-field electrogram. Determining the advance pacing delay also includes determining the advance pacing delay based on the reference point. The advance pacing delay is a delay time period from the delivery of a test LV septal pacing pulse of the test LV septal pacing to the reference point. The reference point is a maximum negative QRS deflection identified within the far-field electrogram.

[0015] 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

[0016] Figure 1 is a schematic diagram of a patient's heart and conduction system.

[0017] Figure 2A is a conceptual diagram illustrating an example 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.

[0018] Figure 2B is a conceptual diagram illustrating an example therapy system (e.g., a three-chamber implantable medical device) configured to provide therapy to the heart of a patient suffering from atrial fibrillation using an IMD via a His bundle or bundle branch pacing lead and a lead placed in the left ventricle.

[0019] Figure 3A is a schematic diagram illustrating an example His bundle or bundle branch pacing lead positioned in the His bundle via the right atrium in a cross-sectional view of the heart.

[0020] 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.

[0021] Figure 3C is a cross-sectional view of a patient's heart implanted with implantable medical electrical leads to deliver bundle branch pacing.

[0022] Figure 3D yes Figure 3C A close up view of the leads in a patient's heart.

[0023] Figure 3E is a conceptual diagram of another example of a medical device system for delivering ventricular cardiac conduction system pacing therapy.

[0024] Figure 3F is a conceptual diagram of yet another example of a medical device system for delivering ventricular cardiac conduction system pacing therapy.

[0025] 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 in the right atrium and a lead placed in the left ventricle.

[0026] Figure 5 is an example FIG. 2A to FIG. 2B as well as FIG. 3B to FIG. 4 A functional block diagram of an example configuration of an implantable medical device.

[0027] Figure 6 It can be seen from Figure 2 to Figure 5 A block diagram of an illustrative method for determining and using an advance pacing delay for cardiac conduction system pacing during atrial fibrillation as utilized by an apparatus.

[0028] Figure 7 It is used to determine the pacemaker used in the cardiac conduction system Figure 6 Block diagram of an illustrative method of advance pacing delay of a method.

[0029] Figure 8 It is used to determine the pacemaker used in the cardiac conduction system Figure 6 Block diagram of another illustrative method of advance pacing delay of the method.

[0030] Fig. 9 is a depiction of exemplary electrocardiogram and electrogram signals at various AV delays, illustrating Figure 8 method.

[0031] Fig.10 It is used to determine the pacemaker used in the cardiac conduction system Figure 6 Block diagram of another illustrative method of advance pacing delay of the method.

[0032] Fig.11 is an exemplary graph of QRS width as a function of pacing rate, illustrating Fig.10 method.

[0033] Fig.12 is an exemplary graph illustrating application of the determined advance pacing delay.

[0034] Fig.13 is an exemplary graph of QRS width as a function of the difference between the pacing rate and the intrinsic rate, which can be applied to Fig.12 activation phase.

[0035] Fig.14 It can be seen from Figure 2 to Figure 5 A block diagram of an illustrative method for determining and using an advance pacing delay for LV septal pacing during atrial fibrillation is provided. DETAILED DESCRIPTION

[0036] 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.

[0037] Will refer to Figures 1 to 14 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.

[0038] Figure 1 is a schematic diagram of the heart 12 . FIG. 2A to FIG. 2B 1 is a conceptual diagram illustrating an example treatment system 10 that can be used to provide treatment to a heart 12 of a patient 14. Patient 14 is typically, but not necessarily, a human. Treatment system 10 includes an IMD 16 coupled to leads 18, 20, 23 and a programmer 24. IMD 16 may be, for example, an implantable pacemaker, cardioverter, and / or defibrillator that provides electrical signals to heart 12 via electrodes coupled to one or more of leads 18, 20, 23. Other non-limiting examples of 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.).

[0039] 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 2AIn 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. In one or more embodiments, the cardiac conduction system treatment lead can be further positioned or positioned into the right ventricle through the tricuspid valve and implanted in the ventricular septum, for example, about 1 cm to 2 cm in the apical direction, as will be referred to herein. FIG. 3C to FIG. 3F Further description.

[0040] 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, activation intervals 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).

[0041] 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.

[0042] 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). SELECTSURE TM 3830 includes two or more conductors with or without lumens.

[0043] An exemplary left ventricular lead having a set of spaced electrodes is shown in U.S. Patent Publication No. WO2019 / 104174A1, 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 8,355,784B2, US 8,96S,5G7, and US 8,126,546, all of which are incorporated by reference and may implement features of the present disclosure.

[0044] In addition, the pacing therapy leads 18, 20, 23 can be used to deliver left ventricular or left ventricular septal pacing to the ventricular septal wall. At least one of the pacing therapy leads 18, 20, 23 can extend through one or more veins, the vena cava, the right atrium 26, and into the coronary sinus 30 to reach an area adjacent to the septal wall of the left ventricle 32 of the heart 12.

[0045] 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. Exemplary left ventricular septal pacing may be described, for example, in U.S. Patent Application Serial No. 16 / 521,000, entitled “AV Synchronous Septal Pacing,” filed on July 24, 2019.

[0046] 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.

[0047] 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. Multi-site pacing may be delivered simultaneously or sequentially, as described and illustrated in U.S. Patent Application Publication No. 2016 / 0339248, filed on April 21, 2016, entitled “EFFICIENT DELIVERY OF MULTI-SITE PACING,” the disclosure of which is incorporated herein by reference in its entirety.

[0048] 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.

[0049] 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 positioned toward the left side of the ventricular septum for left bundle branch pacing, and the second electrode (proximal) toward the right side of the ventricular septum for right bundle branch pacing. 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 mm, 4 mm, 5 mm, 6 mm, 7 mm, or 8 mm (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.

[0050] 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.

[0051] 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).

[0052] 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.

[0053] 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 accompanying 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.

[0054] 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.

[0055] 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.

[0056] Further, the near-field signal or the far-field signal can be used to adjust or configure the advance pacing delay. Each of the following exemplary embodiments will be discussed in more detail herein. For example, a left bundle branch electrocardiogram or electrogram can be monitored at multiple AV delays or at multiple pacing rates, and the electrical activity of the earliest QRS deflection illustrated can be used to determine the advance pacing delay. Also for example, a left bundle branch electrocardiogram or electrogram illustrating an AV delay associated with fusion pacing and a left bundle branch electrocardiogram or electrogram illustrating the shortest AV delay associated with ineffective LV capture can both be used to determine the advance pacing delay, as described below. For another example, a left ventricular septum electrocardiogram or electrogram illustrating an AV delay associated with a maximum negative QRS deflection can be used to determine the advance pacing delay of the LVSP.

[0057] Effective fusion can be described as synchronizing the timing of LV pacing with the earliest activation on the RV chamber. For example, in a fusion pacing configuration, a medical device can deliver one or more fusion pacing pulses to the later contracting left ventricle (LV) in order to pre-excite the LV and synchronize the depolarization of the LV with the depolarization of the earlier contracting right ventricle (RV). The ventricular activation of the LV may "fuse" or "merge" with the ventricular activation of the RV due to the intrinsic conduction of the heart. In this way, the intrinsic and pacing-induced excitation wavefronts can fuse together, thereby resynchronizing the depolarization of the LV with the depolarization of the RV.

[0058] Still further, the left bundle branch electrocardiogram following the post-blanking period following ventricular pacing may be analyzed to determine whether the cardiac conduction system pacing therapy was selective or non-selective.

[0059] Thus, near-field electrical signals and / or far-field electrical signals can be used to determine the pacing rate that results in a particular QRS morphology. For example, far-field electrical signals can be sensed in a far-field electrogram (EGM) monitored by IMD 16 and corresponding leads or a separate device (such as a subcutaneously implanted device).

[0060] As used herein, the term "far-field" electrical signals refers to the results of measuring cardiac activity using sensors or electrodes located outside the region of interest. For example, ECG signals measured from electrodes located outside a patient's heart are an example of far-field electrical signals of the patient's heart. As another example, far-field electrical signals representing electrical activity of a patient's heart chamber may be measured from sensors or electrodes located in an adjacent chamber.

[0061] 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 located to the left of a patient's ventricular septum is an example of a near field electrical signal of a patient's LV.

[0062] 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.

[0063] 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.

[0064] 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 TM 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.

[0065] 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.

[0066] Figure 2B 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.

[0067] 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 2B 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.

[0068] 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.

[0069] 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 Figure 2B and Figure 3BAs shown in , IMD 16 includes one or more housing electrodes, such as housing electrode 58, which can 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 can be defined by an uninsulated portion of the outwardly facing portion of housing 60 of IMD 16. Electrode 50 can be used for pacing and / or sensing of cardiac conduction system tissue (e.g., His bundle tissue or bundle branch tissue). Other separations between the insulated and non-insulated portions of housing 60 can 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 can 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 can enclose a stimulation generator that produces cardiac pacing pulses and defibrillation or cardioversion shocks (see Figure 5 ), and a sensing module for monitoring the patient's heart rhythm.

[0070] 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.

[0071] The pressure sensor 38 may be coupled to one or more coil conductors within the lead 18. Figure 2B In 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.

[0072] Figure 3BIMD 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.

[0073] 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 723 in the patient's heart 12. In some embodiments, electrical lead 723 can be the only lead implanted in the patient's heart 12. In other embodiments as discussed herein, there can be multiple leads implanted in the patient's heart 12. For example, the one or more implantable electrodes can include a pacing electrode that can be implanted proximate to the cardiac conduction system, or can be implanted in the ventricular septum to deliver cardiac conduction system pacing therapy.

[0074] In one embodiment, lead 723 can be configured for dual-bundle pacing. Lead 723 can be used with 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 2B ), 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.

[0075] Electrode assembly 761 may be described as a monopolar cathode electrode that may be implanted on the left side of the patient's diaphragm. Electrode 752 may be described as a monopolar cathode electrode that may be implanted on the right side of the patient's diaphragm.

[0076] 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.

[0077] 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.

[0078] Figure 3E is a conceptual diagram of lead 818 configured as a quadripolar lead carrying four electrodes, electrode 832, electrode 834, electrode 842, and electrode 844, along a single lead body of lead 818. As described above, a plurality of pacing electrode configurations are selectable for delivering bundle branch pacing using electrodes 832, electrode 834, electrode 842, and / or electrode 844 in various unipolar and / or bipolar pacing electrode vectors and selectable anode and cathode polarity assignments for each electrode electrode 832, electrode 834, electrode 842, and electrode 844. For example, tip electrode 832 and ring electrode 834 may deliver bipolar pacing pulses for capturing the LBB, and ring electrode 842 and ring electrode 844 may deliver bipolar pacing pulses for capturing the RBB using two different bipolar pacing electrode vectors. Alternatively, a single bipolar pacing electrode vector (e.g., tip electrode 832 paired with either electrode 834, electrode 842, or electrode 844) may be selected to deliver bipolar bilateral bundle branch pacing including cathode and anodal capture. Any combination of two electrodes of electrodes 832, 834, 842, and 844 may be selected in a bipolar pacing electrode vector with selectable anode and cathode polarities to achieve bipolar bilateral bundle branch pacing using a single bipolar pacing electrode vector. The selected electrode combination may be based on anode and cathode pacing capture thresholds for LBB and RBB, and / or based on maximum improvement in ventricular electrical synchronization based on analysis of ECG and / or EGM signals according to the techniques disclosed herein.

[0079] In addition, any of electrodes 832, 834, 842, and 844 may be selected as a pacing cathode electrode in a unipolar pacing electrode vector of a pacemaker housing 815 that includes pacing of the RBB or LBB. Two unipolar pacing electrode vectors may be selected based on the minimum pacing pulse output required to capture both the RBB and the LBB. However, in some examples, correction of ventricular conduction conditions and improvement of ventricular electrical synchronization may be achieved by a cardiac conduction system pacing therapy that includes only single bundle branch pacing (e.g., only LBB pacing or only RBB pacing) using a selected bipolar or unipolar pacing electrode vector with only cathode capture at the selected cathode electrode. As described herein, one or more processors, one or more processing circuits, and / or computing devices of the pacemaker 814 may analyze EGM signals to determine an advance pacing delay for delivering cardiac conduction system pacing therapy during atrial fibrillation.

[0080] Figure 3F 8 is a conceptual diagram of a pacemaker 814 configured as a multi-chamber pacemaker including an RA pace and sense lead 919 and a coronary sinus (CS) lead 992 and a lead 918 configured for delivering bundle branch pacing. Figure 3E Atrial lead 919 is not shown in the drawings, but it should be understood that the various pacing lead and electrode configurations described herein and shown in the drawings for delivering cardiac conduction system pacing therapy may include an atrial lead 919 for providing atrial sensing and pacing and enabling the pacemaker 814 to deliver atrial synchronous ventricular pacing. FIG. 3E to FIG. 3F Any of the leads shown in the drawings carrying one or more electrodes may be combined in other combinations than the illustrative examples presented herein, with more or fewer leads and / or electrodes than shown in these examples.

[0081] exist Figure 3F , the pacemaker 814 is shown coupled to the RA lead 919, which carries a pacing tip electrode 936 and a proximal ring electrode 938 that can be used to sense RA signals and deliver atrial pacing to the RA. The CS lead 992 can be advanced into the RA, through the coronary sinus ostium and into the cardiac veins of the LV to position electrodes 94a, 94b, 94c and 94d (collectively referred to as electrodes 94) on the epicardium along the LV myocardium to sense EGM signals and pace the LV myocardium. The CS lead 992 is shown as a quadripolar lead carrying four electrodes 94a to 94d, which can be selected from a variety of bipolar pacing electrode pairs to pace the LV myocardial tissue and sense LV epicardial EGM signals. One of the CS electrodes 94 can be selected in conjunction with the pacemaker housing 815 (or coil electrode 935, if available) to deliver unipolar LV myocardial pacing and / or sense unipolar ventricular EGM signals.

[0082] In this example, the pacemaker 814 may be capable of delivering a high voltage CV / DF shock therapy for cardioversion or defibrillation of the heart in response to detecting a ventricular tachyarrhythmia. Thus, the lead 918 is shown as carrying a coil electrode 35 for delivering a high voltage shock pulse. In various examples, one or more coil electrodes may be included along one or more of the leads 918, 919, or 992. A coil electrode such as coil electrode 935 may be selected in a unipolar pacing electrode vector with any of the lead-based tip or ring electrodes 932, 934, 936, 938, or 94 to sense a unipolar EGM signal for analyzing and determining ventricular conduction conditions. In some cases, the coil electrode 935 may be used with the housing 815 to sense a far-field EGM signal for analyzing the QRS signal to determine the ventricular conduction condition and select a cardiac conduction system pacing therapy.

[0083] When pacing lead 918 is positioned for delivering bundle branch pacing of one or both bundle branches, cardiac conduction system pacing therapy can be combined with ventricular myocardial pacing of the LV (using CS lead 992) to correct LV conduction delays and achieve electrical and mechanical synchronization of the ventricles. Thus, in some examples, one or more processors, one or more processing circuits, or computing devices of pacemaker 814 can select cardiac conduction system pacing therapy plus LV myocardial pacing therapy, which LV myocardial pacing therapy includes, for example, single bundle branch pacing or dual bundle branch pacing (e.g., using lead 918) combined with LV myocardial pacing using CS lead 992. As described below, one or more processors, one or more processing circuits, or computing devices of pacemaker 814 can receive EGM signals using one or more electrodes as further described herein (e.g., tip electrode to RV coil electrode monopolar EGM, tip electrode to shell electrode monopolar EGM, etc. as described below) to determine an advance pacing delay as further described herein. In various examples, two or more EGM signals sensed using two or more corresponding sensing electrode vectors selected from available electrodes connected to the pacemaker 814 and, in some cases, to the housing 815 can be analyzed by the pacemaker 814 to determine an advance pacing delay, as further described herein.

[0084] 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 414, 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.

[0085] 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 1 ). As 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. As another example, the therapy system may include a single lead extending from IMD 16 into left ventricle 32 to deliver LVSP. Examples of such therapy systems include Figure 3A and FIG. 3C to FIG. 3E As 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.

[0086] 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. 3B 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.

[0087] The cardiac conduction system pacing lead 23 can be in the form of a spiral (also referred to as a spiral electrode) and 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 and right 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.

[0088] Figure 5 8 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.

[0089] 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.

[0090] 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.

[0091] 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.

[0092] 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.

[0093] 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.

[0094] 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. 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.

[0095] 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.

[0096] 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.

[0097] The intervals defined by the pacemaker timing and control module can include atrial and ventricular pacing escape intervals, refractory periods during which the sensed P and R waves are ineffective for restarting the timing of the escape interval, and the pulse width of the pacing pulse. 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 pulse. The pacemaker timing and control module can also determine the advance pacing delay using the various pacing settings discussed above. As further described herein, the advance pacing delay represents a time period or time period delay from the delivery of the pacing pulse to the ventricular event.

[0098] 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.

[0099] 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.

[0100] 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.

[0101] 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.

[0102] The exemplary devices and methods described herein may provide and use advance pacing delays for cardiac therapy and cardiac resynchronization therapy (CRT), such as cardiac conduction system pacing and left ventricular septal pacing (LVSP). The advance pacing delay represents the time period for delivering a pacing pulse (e.g., a cardiac conduction system pacing pulse such as a left bundle branch pacing pulse) to a ventricular event (e.g., a sudden myocardial depolarization). Using the advance pacing delay, the IMD can effectively capture and pace the LV during atrial fibrillation. For example, exemplary CRT and effective capture of the left ventricle during CRT are described in U.S. Patent No. 9,339,656B2, entitled "Methods and systems for identifying causes for ineffective left ventricular capture in care based on EGMmorphology" filed on February 28, 2014. Exemplary pacing therapy may be delivered using an advance pacing delay to effectively capture the left ventricle (LV). The advance pacing delay for cardiac conduction system pacing and the advance pacing delay for LVSP may be the same or different values, as will be further described herein.

[0103] Figure 6 Depicted can be Figure 2 to Figure 5 An exemplary method 100 for determining and using an advance pacing delay for pacing a cardiac conduction system during atrial fibrillation is provided for use with a device of the invention. The method 100 may optionally include (e.g., as shown in a dashed box) determining atrial fibrillation 102. In some embodiments, the advance pacing delay may be determined during the occurrence of atrial fibrillation, and in some other embodiments, the advance pacing delay may be determined when atrial fibrillation is not occurring. It should be understood that any one or more methods or techniques known in the art may be used to determine or detect atrial fibrillation. Exemplary determination of atrial fibrillation may be described, for example, in U.S. Pat. No. 7,146,206 B2, filed on March 6, 2003, entitled “Detection of cardiac arrhythmia using mathematical representation of standard ΔRR probability density histograms,” and, for example, in U.S. Pat. No. 7,233,822 B2, filed on June 29, 2004, entitled “Combination of electrogram and intra-cardiac pressure to discriminate between fibrillation and tachycardia.”

[0104] In response to determining that atrial fibrillation is occurring 102 or in embodiments that do not utilize process 102, method 100 may also include determining an advance pacing delay 104. When a cardiac conduction system pacing pulse is initiated, it may 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. The time it takes for a pacing pulse to travel from a cardiac conduction system pulse location (e.g., left bundle branch, right bundle branch, bundle of His, AV node, SA node, etc.) to a sudden myocardial depolarization (e.g., left ventricular or right ventricular myocardium) may be equivalent to an advance pacing delay as used herein.

[0105] In some embodiments, where the cardiac conduction system pulse is delivered to the left bundle branch, the advance pacing delay is equivalent to the time it takes for the pulse to be conducted from the left bundle branch (LBB) to the sudden LV myocardial depolarization. In such embodiments, it is also necessary to effectively capture the LBB so that most of the sudden LV myocardial depolarization occurs via activation of the LBB (e.g., as opposed to myocardial activation near the implanted electrode). Pacing based on or using the advance pacing delay can effectively capture the LBB.

[0106] In response to or after determining the advance pacing delay 104, the method 100 may also include delivering cardiac conduction system pacing using an advance pacing delay 106. Various embodiments describing the delivery of cardiac conduction system pacing are described above (e.g., using an IMD). Delivering cardiac conduction system pacing using an advance pacing delay can be delivering cardiac conduction system pacing so that each pacing pulse is initiated "early" at a time equal to the advance pacing delay. The early refers to the pacing pulse being initiated before the time it should have been initiated. For example, pacing pulses can be delivered during atrial fibrillation so that they occur before or beyond the intrinsic heartbeat in order to effectively capture the LV. The advance pacing delay can help limit how early each pacing pulse can be delivered in order to successfully surpass the intrinsic heart rate or intrinsic heartbeat / intrinsic activation. This can provide pacing therapy (e.g., CRT) that effectively captures the LV during atrial fibrillation, which can result in improved stroke volume and cardiac output during atrial fibrillation.

[0107] In one embodiment, delivering cardiac conduction system pacing using the advance pacing delay 106 may include increasing the pacing rate of the cardiac conduction system pacing based on the advance pacing delay. Increasing the pacing rate of the cardiac conduction system pacing may result in faster pacing of the patient's heart during atrial fibrillation in order to exceed the intrinsic heart rate, and the advance pacing delay may be used to ensure effective LBB capture and effective LV capture during cardiac conduction system pacing. Figures 7 to 13 Various examples of determining advance pacing delay are described.

[0108] Figure 7Describes the determination of the use of pacing in the cardiac conduction system Figure 6 104A. As shown, method 104A may include delivering a test cardiac conduction system pacing to a patient's cardiac conduction system using a cardiac conduction system electrode implanted proximate a portion of the patient's cardiac conduction system 108. Delivering the test cardiac conduction system pacing 108 occurs during atrial fibrillation and may capture the cardiac conduction system (such capture of the cardiac conduction system as described above). The test cardiac conduction system pacing may be performed as described above with reference to FIGS. 2 to 3. Figure 5 The described systems and devices deliver. Test cardiac conduction system pacing is referred to as "test" cardiac conduction system pacing because in this case it is not used for cardiac therapy, but rather to determine advance pacing delays.

[0109] Method 104A may also include the above reference Figures 1 to 5 Monitoring far-field electrical activity 110 as described. Monitoring electrical activity may include monitoring near-field electrical signals or far-field electrical signals using the systems and devices described above. In one embodiment, monitoring electrical activity may include using one or more surface electrodes (e.g., a standard 12-lead ECG), including, for example, electrodes positioned on the surface of the patient near or at standard I, II, III, IV, V, and VI chest leads and / or right upper and left arm and right lower and left leg limb leads. In the same embodiment, monitoring electrical activity may also include using the above with respect to Figures 1 to 5 The one or more implanted electrodes discussed include, for example, a tip electrode to the RV coil electrode monopolar EGM, a tip electrode to the shell electrode monopolar EGM, an RV coil electrode to the shell electrode monopolar EGM, and an atrial ring electrode to the 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 the 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, for example, an electrode located in or around the IMD shell. Position identifiers such as the RV are examples of possible electrode locations. For example, the "atrial" position can be an atrium in any atrium. In alternative embodiments, for example, bipolar EGM signals can be monitored. In alternative embodiments, only surface electrodes or only implanted electrodes can be used. One or more surface electrodes and one or more implanted electrodes can include any other electrodes or electrode positions known to those of ordinary skill in the art that are not specifically described herein.

[0110] Method 104A may also include configuring or setting one or more parameters of the cardiac conduction system for determining the early pacing delay. For example, as shown, method 104A may include setting a short AV delay 112 and / or setting a rapid pacing rate 114. The short AV delay may be between about 5 milliseconds (ms) and about 70 ms. In at least one embodiment, the short AV delay is 30 ms. In other embodiments, the short AV delay may be greater than or equal to 2 ms, greater than or equal to 15 ms, greater than or equal to 30 ms, greater than or equal to 40 ms, greater than or equal to 50 ms, greater than or equal to 60 ms, etc., and / or less than or equal to 80 ms, less than or equal to 75 ms, less than or equal to 70 ms, less than or equal to 60 ms, less than or equal to 50 ms, less than or equal to 40 ms, etc.

[0111] In another embodiment, the short AV delay can be determined to be related to or as a function of the patient's intrinsic AV delay. For example, the short AV delay can be configured as a selected or set percentage or ratio of the patient's intrinsic AV delay. In another embodiment, the short AV delay can be configured to be a selected or set period of time less than the patient's intrinsic AV delay.

[0112] The rapid pacing rate can be about 10 beats per minute (bpm) faster to about 15 bpm faster than the patient's intrinsic or observed heart rate. In at least one embodiment, the rapid pacing rate is 5 bpm faster than the patient's intrinsic or observed heart rate. In other embodiments, the rapid pacing rate can be greater than or equal to 2 bpm, greater than or equal to 12 bpm, greater than or equal to 18 bpm, greater than or equal to 20 bpm, greater than or equal to 22 bpm, greater than or equal to 25 bpm, etc., and / or less than or equal to 20 bpm, less than or equal to 15 bpm, less than or equal to 12 bpm, less than or equal to 10 bpm, less than or equal to 5 bpm, less than or equal to 2 bpm, etc.

[0113] In another embodiment, the rapid pacing rate can be determined to be related to or as a function of the patient's intrinsic heart rate. For example, the rapid pacing rate can be configured as a selected or set percentage or ratio of the patient's intrinsic heart rate. In another embodiment, the rapid pacing rate can be configured to be a set number of beats per minute that is faster than the patient's intrinsic heart rate.

[0114] The method 104A may also include monitoring far-field electrical activity using one or more implanted electrodes during delivery of the test cardiac conduction system pacing 110. As described above, monitoring far-field electrical activity may be accomplished using, for example, the sensing module 86. The far-field electrical activity may include far-field electrogram (EGM) signals sensed from at least one implanted electrode. In alternative embodiments, the far-field electrical activity may include, for example, far-field electrocardiogram (ECG) signals sensed from external electrodes. The sensing module 86 or other sensing device may monitor far-field electrical activity (e.g., EGM signals) during delivery of the test cardiac conduction system pacing 108.

[0115] Method 104A may also include determining a reference point within the far-field electrical activity 116. The reference point may be any measurable point within the far-field electrical activity signal. To determine the reference point, the apparatus and system described above may use any calculation known to a person of ordinary skill in the art to identify the reference point. Some examples of reference points may include one or more of the following: the starting point of the QRS morphology or any specific point therein, the maximum signal amplitude, the minimum signal amplitude, the minimum signal slope, and the maximum signal slope, etc. In one embodiment, the reference point is the earliest QRS deflection identified within the monitored far-field electrical activity after a pacing pulse to the test cardiac conduction system.

[0116] The method 104A may also include determining an advance pacing delay based on the determined reference point 118. In one embodiment, the advance pacing delay may be determined as a delay period from delivery of a test cardiac conduction system pacing pulse of the test cardiac conduction system pacing to the determined reference point. Further, for example, the advance pacing delay may be determined as a delay period from delivery of a test cardiac conduction system pacing pulse of the test cardiac conduction system pacing to the earliest QRS deflection monitored on the far-field EGM (i.e., time from LBB pacing pulse to burst LV myocardial depolarization).

[0117] Figure 8 and Fig. 9 Describes the determination of the use of pacing in the cardiac conduction system Figure 6 Another exemplary method of the method of advance pacing delay 104B. Fig. 9 Depicted are exemplary electrocardiogram and electrogram signals monitored during delivery of cardiac conduction system pacing at a plurality of different AV delays.

[0118] Method 104B (eg Figure 8 ) may include delivering test cardiac conduction system pacing at a plurality of different AV delays within the test time period 120, such as Fig. 9As shown in method 104B, test cardiac conduction system pacing is typically not delivered during atrial fibrillation because electrical activity during atrial fibrillation may be inconsistent and difficult to monitor. For example, each of the plurality of AV delays may correspond to a single paced heartbeat. For example, Fig. 9 As shown, the plurality of AV delays may be any number of AV delays ranging between about 20 ms and about 200 ms. In other embodiments, the range of AV delays may be, for example, between about 10 ms and about 300 ms, or between about 5 ms and about 250 ms, or between about 3 ms and about 400 ms. The AV delays may be any AV delay within the range and do not necessarily need to be in increments of 20 ms, such as Fig. 9 As shown. For example, the AV delay may include every AV delay possible within the range, or may be stepped, for example, in increments of 1 ms or 5 ms or 10 ms or 25 ms. For example, the longest AV delay may be the AV delay that results in a pacing rate that does not exceed an intrinsic heartbeat. In other words, the longest AV delay may be the AV delay that results in, for example, an intrinsic heartbeat and an intrinsic activation.

[0119] Method 104B may also include monitoring electrical activity using one or more implanted electrodes during delivery of test cardiac conduction system pacing 122. Electrical activity may be monitored over any suitable time period, such as a time period that includes each of a plurality of different AV delays tested on consecutive heartbeats.

[0120] Monitoring electrical activity 122 can include monitoring near-field electrical signals or far-field electrical signals using systems and devices as described above. In one embodiment, monitoring electrical activity can include using one or more surface electrodes as described above. In another embodiment, monitoring electrical activity can include using one or more implanted electrodes as described above. In another embodiment, monitoring electrical activity can include using one or more surface electrodes and one or more implanted electrodes.

[0121] Method 104B may also include identifying a fused AV delay among the plurality of AV delays based on the monitored electrical activity 124. A fused AV delay is an AV delay in which pacing of the test cardiac conduction system results in fusion. Fusion is described above as synchronizing the timing of LV pacing with the earliest activation on the RV chamber. Fig. 9 In the depicted exemplary embodiment, the fused AV delay 124A occurs at an AV delay of, for example, 120 ms. As known to one of ordinary skill in the art, identifying the fused AV delay based on the monitored electrical activity can be accomplished or performed by analyzing the electrical activity, such as morphology analysis, timing between reference points, etc. For example, when the electrical activity monitored from the VI surface electrode leads shows a loss of R wave morphology, the fused AV delay may be the shortest AV delay (e.g., Fig. 9In another embodiment, the fused AV delay may be the AV delay for which the electrical activity monitored from the VI surface electrode leads shows the narrowest QRS complex morphology. In another embodiment, the fused AV delay may be the shortest AV delay that results in fusion. In another embodiment, as described above, the fused AV delay may be the longest AV delay before fusion is first identified.

[0122] The method 104B may also include identifying an effective captured AV delay among the plurality of AV delays based on the monitored electrical activity 126. Fig. 9 In the depicted exemplary embodiment, the effective capture AV delay 126A occurs at an AV delay of, for example, 180 ms. As known to those of ordinary skill in the art, identifying the effective capture AV delay based on the monitored electrical activity can be accomplished or performed by analyzing the electrical activity, such as morphological analysis, timing between reference points, etc. For example, the effective capture AV delay can be the longest AV delay at which the test cardiac conduction system pacing results in effective capture of the patient's LV (or can be the shortest AV delay at which the test cardiac conduction system pacing results in ineffective capture of the patient's LV, such as Fig. 9 ). Effective capture of the LV can be determined using any device, system, or method known to one of ordinary skill in the art. For example, the "EFFECTIVCRT TM The "DURING AF" feature classifies individual heartbeats as valid, invalid, or sensed based on the pattern of electrical activity. Trademark EFFECTIVCRT TM The use of has been indicated in this application.

[0123] In response to identifying the fused AV delay of the plurality of AV delays 124 and the valid captured AV delay of the plurality of AV delays 126, the method 104B may further include determining an early pacing delay based on the fused AV delay and the valid captured AV delay 128. For example, the early pacing delay may be determined by calculating a difference between the two identified AV delays. Fig. 9 As shown, the difference 127 between AV delay 124A and 126A is 60ms. Therefore, 60ms is used Fig. 9 The advance pacing delay determined by monitoring electrical activity of . In alternative embodiments, the advance pacing delay can be a different calculated value, such as 50 ms, and as described above.

[0124] Fig.10 Describes the determination of the use of pacing in the cardiac conduction system Figure 6 Another exemplary method of the method of advance pacing delay 104C. Fig.11 An illustrative graph depicting QRS width as a function of pacing rate is depicted to illustrate method 104C.

[0125] like Fig.11 As shown, for example, in patients with a common conduction abnormality of left bundle branch block, rapid pacing during atrial fibrillation typically results in a wide QRS width as a right bundle branch block (RBBB) pattern. Slow pacing during atrial fibrillation typically results in a wide QRS width as a left bundle branch block (LBBB). Intrinsic activation (or pseudofusion) is similar to slow pacing, typically resulting in a wide QRS width that is a LBBB pattern. Pseudofusion occurs when a ventricular pacing output is delivered, but too late to significantly change the intrinsic QRS morphology. In contrast, fusion typically results in a narrower QRS width than the LBBB or RBBB patterns (e.g., Fig.11 and Fig.13 shown).

[0126] Method 104C may include delivering test cardiac conduction system pacing at a plurality of pacing rates during test period 130, such as Fig.10 As shown. Delivery test cardiac conduction system pacing as shown in method 104C is typically accomplished during atrial fibrillation. For example, cardiac conduction pacing can be delivered at each of a plurality of delivered pacing rates during a single heartbeat or multiple heartbeats. The plurality of pacing rates can be any number of pacing rates within a range of about 15 bpm to about 20 bpm faster than the patient's intrinsic heart rate or the patient's most recently observed pacing rate. In other embodiments, for example, the range of pacing rates can be between about 0 bpm to about 30 bpm faster than the intrinsic or observed rate, or between about 10 bpm to about 20 bpm faster than the intrinsic or observed rate, or between about 15 bpm to about 20 bpm faster than the intrinsic or observed rate, or between about 5 bpm to about 15 bpm faster than the intrinsic or observed rate, or between about 10 bpm to about 15 bpm faster than the intrinsic or observed rate. As Fig.11 As shown, the pacing rate can be any pacing rate within the selected range.

[0127] Method 104C may also include monitoring electrical activity during delivery of test cardiac conduction system pacing at a plurality of different pacing rates using one or more implanted electrodes 132. Electrical activity may be monitored over any suitable time period, such as a time period that includes each of a plurality of pacing rates, each pacing rate being tested over a range of a plurality of heartbeats.

[0128] Monitoring electrical activity 132 can include monitoring near-field electrical signals or far-field electrical signals using systems and devices as described above. In one embodiment, monitoring electrical activity can include using one or more surface electrodes as described above. In another embodiment, monitoring electrical activity can include using one or more implanted electrodes as described above. In another embodiment, monitoring electrical activity can include using one or more surface electrodes and one or more implanted electrodes.

[0129] Method 104C may also include identifying a fusion pacing rate from among the plurality of pacing rates based on the monitored electrical activity 134. The fusion pacing rate may be a pacing rate at which pacing of the test cardiac conduction system results in fusion. Identifying the fusion pacing rate based on the monitored electrical activity may be performed using any modality of identification or calculation as known to one of ordinary skill in the art. For example, the fusion pacing rate may occur at a pacing rate having the narrowest QRS width, such as Fig.11 shown.

[0130] Method 104C may also include identifying an effective captured pacing rate from among a plurality of pacing rates based on the monitored electrical activity 136. For example, Fig.11 In the depicted exemplary embodiment, the effective capture pacing rate occurs at a pacing rate that is slower than the fusion pacing rate. Identifying the effective capture pacing rate based on the monitored electrical activity can be performed using any modality of identification or calculation as known to those of ordinary skill in the art. For example, the effective capture pacing rate can be the slowest pacing rate at which test cardiac conduction system pacing results in effective capture of the patient's LV (or can be the fastest pacing rate at which test cardiac conduction system pacing results in ineffective capture of the patient's LV), such as Fig.11 As shown. Effective capture of the LV can be determined using any device, system, or method known to those of ordinary skill in the art. For example, the "EFFECTIVCRT TM The "DURING AF" feature classifies individual heartbeats as valid, invalid, or sensed based on the pattern of electrical activity. Trademark EFFECTIVCRT TM The use of has been indicated in this application.

[0131] In one or more of the above embodiments, conduction disorders of LBBB are described. In one or more alternative embodiments, patients with RBBB will have Fig.11 The pattern is substantially the opposite of the pattern (such that the pattern is flipped longitudinally in the x-direction and the x-axis values ​​are reversed so that, for example, the x-axis provides increasing advance pacing delay from left to right, rather than as currently Fig.11 In such alternative embodiments, if the advance pacing delay is too short, an RBBB pattern is produced. If the advance pacing delay is too long, an LBBB pattern is produced. Identifying the fusion pacing rate can be similar to the embodiments described herein when the narrowest QRS width is identified. For patients with RBBB, selecting an AV delay that optimizes fusion between conduction system pacing and intrinsic activation can be similar to one or more embodiments described above.

[0132] In response to identifying a fused pacing rate of the plurality of pacing rates 134 and an effective captured pacing rate of the plurality of pacing rates 136, the method 104C may further include determining an advance pacing delay based on the fused pacing rate and the effective captured pacing rate 138. For example, the advance pacing delay may be determined by calculating a difference between the two identified pacing rates. Fig.11 As shown, the pacing rate is calculated in bpm and the advance pacing delay X is calculated in ms. This conversion from a rate in bpm to a time delay in ms can be accomplished in a variety of ways. For example, the difference in pacing rates can be converted from bpm to ms by multiplying the two pacing rates by a conversion factor from minutes to milliseconds. One of ordinary skill in the art will appreciate various ways to convert a pacing rate in bpm to an advance pacing delay in ms, and vice versa. The advance pacing delay can be a value within the ranges described above.

[0133] Once the advance pacing delay is determined using any of the above methods or embodiments, the advance pacing delay can be used to deliver cardiac conduction system pacing (e.g., Figure 6 106 shown). In one embodiment, the advance pacing delay can be determined once for each patient and then used as a consistent value. In one embodiment, the advance pacing delay can be determined based on a patient population and then used as a default or nominal value for all subsequent patients. In one embodiment, the advance pacing delay can be determined on a regular basis and further adapted over time after each subsequent determination. Each of the above embodiments can be used alone or together as needed.

[0134] Fig.12 Depicted are exemplary graphs of heart rate as a function of time during a maintenance phase, an activation phase, and another maintenance phase. Generally, the maintenance phase includes delayed delivery of cardiac conduction system pacing using advance pacing, such as in Figure 6 In the process 106 shown. Generally speaking, the activation phase includes removing the advance pacing delay from the pacing rate, so that the pacing cycle length increases by X ms and a slower intrinsic paced heart rate or observed paced heart rate occurs. During the activation phase, the boundary between valid capture and invalid capture of the LBB can be reanalyzed.

[0135] The method 100 as described above may also include delivering cardiac conduction system pacing according to a maintenance pacing rate during the maintenance phase (e.g., Fig.12 During the maintenance phase, the cardiac conduction system pacing rate is increased to ensure that the intrinsic heart rate during atrial fibrillation is covered (as described above with respect to the test cardiac conduction system pacing rate) and a significant portion of the LV myocardium is depolarized by the cardiac conduction system pacing pulses.

[0136] Method 100 may also include delivering cardiac conduction system pacing according to a plurality of activation pacing rates during the activation phase (e.g., Fig.12 ). During the transition from the maintenance phase to the activation phase, the pacing cycle length is increased by a selected amount. For example, the selected amount can be equivalent to the calculated advance pacing delay. Increasing the cycle length by advance pacing delay slows the pacing heart rate. The slower pacing heart rate is used to determine the transition point between invalid capture and effective capture. The determination of the transition point between invalid capture and effective capture is used to ensure effective capture of the patient's cardiac conduction system. In other words, as the pacing cycle length extends over more time, the pacing rate is reduced. During the activation phase, the pacing rate can be adjusted after each consecutive heartbeat. Since cardiac conduction system pacing will not be as effective as with an extended pacing cycle length, the activation phase is not lengthy. In addition, power consumption during the maintenance phase is lower than power consumption during the activation phase, so the activation phase keeps battery life shorter than the maintenance phase.

[0137] During the activation phase, if the pacing rate is determined to be effectively capturing the patient's cardiac conduction system (using the systems, devices, and methods discussed and incorporated herein), the pacing rate may be reduced ( Fig.12 If the pacing rate is determined to be ineffective in capturing the patient's cardiac conduction system, then Fig.12 In an alternative embodiment, the cardiac conduction system pacing rate can be gradually decreased during the activation phase to find the boundary where ineffective LV capture occurs.

[0138] Fig.13 is an exemplary graph of QRS width as a function of the difference between the pacing rate and the intrinsic rate. Fig.12 During the activation phase of the method 104C, the pacing rate can be modified and the QRS width can be monitored to reanalyze the boundary between effective and ineffective capture of the LBB and provide continued effective capture of the LBB. The difference between the pacing rate and the intrinsic rate can be as described above with respect to methods 104C and Fig.11 described.

[0139] Essentially, based on the QRS morphology, more specifically based on the QRS width, effective capture of the LBB can be continuously ensured. Fig.11As described above, rapid pacing during atrial fibrillation typically results in a wide QRS width that indicates RBBB and can therefore be referred to as an RBBB pattern. Intrinsic activation (or pseudofusion) typically results in a wide QRS width that indicates LBBB and can therefore be referred to as an LBBB pattern. Pseudofusion occurs when a ventricular pacing output is delivered, but too late to significantly change the intrinsic QRS morphology. In contrast, fusion typically results in a narrower QRS width than the LBBB or RBBB patterns (e.g., Fig.11 and Fig.13 shown).

[0140] For example, during the activation phase, the pacing rate can be adjusted without applying an advance pacing delay, while the QRS width can be monitored or measured. For example, multiple different pacing rates (e.g., different rates for each beat, for a group of beats, etc.) can be applied one at a time, for example, each without applying an advance pacing delay. In addition, multiple different pacing rates can be defined based on intrinsic rates. For example, Fig.13 As shown, the different pacing rates extend from 5 bpm less than the intrinsic rate ("-5") to 30 bpm greater than the intrinsic rate ("+30"). More specifically, the plurality of different pacing rates can be any number of pacing rates within a range of about 0 bpm to about 20 bpm faster than the patient's intrinsic heart rate or the patient's most recently observed pacing rate. In other embodiments, for example, the range of pacing rates can be between about 0 bpm to about 30 bpm faster than the intrinsic or observed rate, or between about 10 bpm to about 20 bpm faster than the intrinsic or observed rate, or between about 15 bpm to about 20 bpm faster than the intrinsic or observed rate, or between about 5 bpm to about 15 bpm faster than the intrinsic or observed rate, or between about 10 bpm to about 15 bpm faster than the intrinsic or observed rate.

[0141] Adjusting the pacing rate without applying an advance pacing delay allows for the same Fig.12 The described beat-by-beat adjustment of the pacing rate. If the LBB is captured effectively, the pacing rate can be reduced. If the LBB is not captured effectively, the pacing rate can be increased. The QRS width can provide an indication of effective capture or ineffective capture of the LBB. For example, a narrow QRS width indicating fusion can provide an indication of effective capture of the LBB. In addition, for example, if the QRS width increases due to a change in the pacing rate, this will correspond to a movement from effective capture of the LBB to ineffective capture. If the QRS width decreases due to a change in the pacing rate, this will correspond to a movement toward effective capture of the LBB.

[0142] Thus, during the activation phase, the QRS width can be measured after each pacing pulse to determine whether effective capture of the LBB has occurred, and the pacing rate can be modified (e.g., increased or decreased) until the pacing rate that provides the narrowest QRS width is determined to indicate fusion, which can then be used to continuously ensure effective LBB capture. In addition, it should be understood that other variables besides QRS width indicating fusion can be used to ensure effective capture of the LBB in a similar manner.

[0143] In one or more of the above embodiments, conduction disorders of LBBB are described. In one or more alternative embodiments, patients with RBBB will have Fig.13 The fusion pacing rate may be identified by identifying the narrowest QRS width, similar to the embodiments described herein.

[0144] In response to delivering cardiac conduction system capture according to a plurality of activation pacing rates during the activation phase, method 100 may further include determining a lowest activation pacing rate that results in effective cardiac conduction system capture (using the systems, devices, and methods discussed and incorporated herein).

[0145] In response to determining the lowest activated pacing rate that resulted in effective cardiac conduction system capture, method 100 may further include setting a maintenance pacing rate (e.g., Fig.12 During the transition from the activation phase to the maintenance phase, the pacing cycle length is reduced by the same selected amount as the amount used to increase the pacing cycle length when transitioning from the maintenance phase to the activation phase. In other words, the pacing rate is increased as the pacing cycle length decreases in less time. This can continue to ensure effective capture of the patient's cardiac conduction system while moving back to the maintenance phase.

[0146] Fig.14 Depicted can be Figure 2 to Figure 5 An exemplary method 300 for determining and using an advance pacing delay for LV septal pacing (LVSP) during atrial fibrillation is provided by a device of the invention.

[0147] Method 300 may include determining an advance pacing delay to capture the patient's LV, wherein the advance pacing delay represents a period of time from the delivery of a pacing pulse (e.g., an LV septal pacing pulse) to a ventricular event (e.g., a sudden myocardial depolarization). Method 300 may be very similar to method 100 and method 104A as described above. Method 300 may also include delivering therapeutic pacing to the patient's LV using one or more implanted electrodes, the one or more implanted electrodes including an electrode implanted proximate a portion of the patient's LV according to the advance pacing delay.

[0148] Method 300 may optionally include determining atrial fibrillation 301, similar to method 100 as described above. In some embodiments, the advance pacing delay may be determined during the occurrence of atrial fibrillation, and in some other embodiments, the advance pacing delay may be determined when atrial fibrillation is not occurring. In response to determining that atrial fibrillation is occurring or in embodiments that do not utilize a process for determining atrial fibrillation, method 300 may also include determining the advance pacing delay.

[0149] In response to determining an advance pacing delay, method 300 may further include delivering LV septal pacing using an advance pacing delay. Various embodiments describing the delivery of LV septal pacing (e.g., using an IMD) are described above. Delivering LV septal pacing using an advance pacing delay can be delivering LV septal pacing such that each pacing pulse is initiated "early" at a time equal to the advance pacing delay. By early is meant that the pacing pulse is initiated before the time at which it should have been initiated. For example, pacing pulses can be delivered during atrial fibrillation such that they occur before or beyond the intrinsic heartbeat in order to effectively capture the LV. The advance pacing delay can help limit how early each pacing pulse can be delivered in order to successfully surpass the intrinsic heartbeat. This can provide pacing therapy (e.g., CRT) that effectively captures the LV during atrial fibrillation, which can result in, for example, improved stroke volume and cardiac output during atrial fibrillation.

[0150] Fig.14 An exemplary method of determining an advance pacing delay for a method 300 for LV septal pacing is depicted. As shown, the method 300 may include delivering a test LV septal pacing 302. Delivering a test LV septal pacing 302 may occur during atrial fibrillation and may capture the LV septal myocardium and other myocardial tissue in the LV. The LV septal pacing may be performed as described above with reference to FIGS. Figure 5 The systems and devices deliver.

[0151] Method 300 may also include configuring or setting one or more parameters of LV septal pacing for determining an advance pacing delay. For example, as shown, method 300 may include setting a short AV delay 112 and / or setting a rapid pacing rate 114, as described above with respect to method 104A.

[0152] Method 300 may also include monitoring far-field electrical activity using at least one of one or more implanted electrodes and one or more surface electrodes (as described above with respect to method 104A) during delivery of test LV septal pacing 110. For example, the one or more implanted electrodes may be implanted in the LV or ventricular septum.

[0153] The method 300 may also include determining a fiducial point within the far-field electrical activity 316. The fiducial point may be any measurable point within the far-field electrical activity signal. To determine the fiducial point, the apparatus and system described above may use any calculation known to one of ordinary skill in the art to identify the fiducial point. Some examples of fiducial points are described above. In one embodiment, the fiducial point is the maximum negative QRS deflection identified within the monitored far-field electrical activity after a test LV septal pacing pulse.

[0154] In response to determining a fiducial point within the far-field electrical activity 316, the method 300 may further include determining an advance pacing delay based on the determined fiducial point 318. In one embodiment, the advance pacing delay may be determined as a delay period from the delivery of a test LV septal pacing pulse of the test LV septal pacing to the determined fiducial point. The advance pacing delay according to this embodiment may be as described above with respect to the method 104A. Determining the advance pacing delay based on the determined fiducial point 318 may be performed by the devices and systems described above using any calculation known to those of ordinary skill in the art.

[0155] In response to determining an advance pacing delay, method 300 may further include delivering LV septal pacing using an advance pacing delay 320. Various embodiments describing the delivery of LV septal pacing (e.g., using an IMD) are described above. Delivering LV septal pacing using an advance pacing delay may be delivering LV septal pacing such that each pacing pulse is initiated "early" at a time equal to the advance pacing delay. By early is meant that the pacing pulse is initiated before the time at which it should have been initiated. For example, pacing pulses may be delivered during atrial fibrillation such that they occur before or beyond an intrinsic heartbeat in order to effectively capture the LV. The advance pacing delay may help limit how early each pacing pulse may be delivered in order to successfully surpass the intrinsic heart rate or intrinsic heartbeat. This may provide a pacing therapy (e.g., CRT) that effectively captures the LV during atrial fibrillation, which may result in improved stroke volume and cardiac output during atrial fibrillation.

[0156] 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.

[0157] Illustrative Embodiments

[0158] 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.

[0159] Embodiment Ex1: An implantable medical device, comprising:

[0160] one or more implantable electrodes for sensing and pacing a patient's heart, wherein the one or more implantable electrodes include a cardiac conduction system electrode positionable proximate a portion of the patient's cardiac conduction system; and

[0161] A computing device comprising processing circuitry, the computing device being operably coupled to the one or more implanted electrodes, wherein the computing device is configured to:

[0162] determining an advance pacing delay to capture the cardiac conduction system, wherein the advance pacing delay represents a period of time from delivery of a cardiac conduction system pacing pulse to a ventricular event;

[0163] as well as

[0164] Delivery of cardiac conduction system pacing is initiated during atrial fibrillation using the cardiac conduction system electrodes based on the advance pacing delay.

[0165] Embodiment Ex2: An implantable medical device according to Embodiment Ex1, wherein initiating delivery of cardiac conduction system pacing during atrial fibrillation using the cardiac conduction system electrodes according to the advance pacing delay comprises: increasing the pacing rate of the cardiac conduction system pacing based on the advance pacing delay.

[0166] Embodiment Ex3: The implantable medical device according to any one of Embodiments Ex1 to Ex2, wherein in order to determine the advance pacing delay, the computing device is further configured to:

[0167] Initiating delivery of test cardiac conduction system pacing during atrial fibrillation using the cardiac conduction system electrodes to capture the cardiac conduction system according to one or more parameters, wherein the one or more parameters include a pacing rate faster than an intrinsic rate and a pacing rate faster than an intrinsic atrioventricular (AV) rate.

[0168] AV delay with short latency;

[0169] monitoring far-field electrical activity using at least one of the one or more implanted electrodes and the one or more surface electrodes during delivery of the test cardiac conduction system pacing;

[0170] determining a reference point within the far-field electrical activity; and

[0171] The advance pacing delay is determined based on the reference point.

[0172] Embodiment Ex4: An implantable medical device according to embodiment Ex3, wherein the advance pacing delay is a delay period from the delivery of a test cardiac conduction system pacing pulse of the test cardiac conduction system pacing to the reference point.

[0173] Embodiment Ex5: An implantable medical device according to any one of Embodiments Ex3 to Ex4, wherein the reference point is the earliest QRS deflection identified within the monitored far-field electrical activity after the test cardiac conduction system pacing pulse.

[0174] Embodiment Ex6: The implantable medical device according to any one of Embodiments Ex1 to Ex5, wherein in order to determine the advance pacing delay, the computing device is further configured to:

[0175] initiating delivery of test cardiac conduction system pacing using the cardiac conduction system electrodes at a plurality of AV delays during a test period;

[0176] monitoring electrical activity using at least one of the one or more implanted electrodes and the one or more surface electrodes during delivery of test cardiac conduction system pacing at the plurality of AV delays during the test time period;

[0177] identifying a fused AV delay among the plurality of AV delays based on the monitored electrical activity, wherein the fused AV delay is the shortest AV delay in which pacing of the test cardiac conduction system results in fusion;

[0178] identifying a valid captured AV delay among the plurality of AV delays based on the monitored electrical activity, wherein the valid captured AV delay is a longest AV delay for which the test cardiac conduction system pacing effectively captures the patient's cardiac conduction system; and

[0179] The advance pacing delay is determined based on the fused AV delay and the effective captured AV delay.

[0180] Embodiment Ex7: The implantable medical device according to any one of Embodiments Ex1 to Ex6, wherein in order to determine the advance pacing delay, the computing device is further configured to:

[0181] determining that the patient is experiencing atrial fibrillation;

[0182] in response to determining that the patient is experiencing atrial fibrillation, initiating delivery of test cardiac conduction system pacing at a plurality of pacing rates over a test time period using the cardiac conduction system electrodes;

[0183] monitoring electrical activity using at least one of the one or more implanted electrodes or the one or more surface electrodes during delivery of test cardiac conduction system pacing at the plurality of pacing rates during the test time period;

[0184] identifying a fusion pacing rate among the plurality of pacing rates based on the monitored electrical activity, wherein the fusion pacing rate is the pacing rate at which pacing of the test cardiac conduction system induces fusion;

[0185] identifying an effective capture pacing rate among the plurality of pacing rates based on the monitored electrical activity, wherein the effective capture pacing rate is the slowest pacing rate at which the test cardiac conduction system pacing effectively captures the patient's cardiac conduction system; and

[0186] The advance pacing delay is determined based on the fused pacing rate and the effective captured pacing rate.

[0187] Embodiment Ex8: An implantable medical device according to embodiment Ex7, wherein the advance pacing delay is the difference between the fusion pacing RR interval (e.g., the interval between two consecutive R waves) provided by the fusion pacing rate and the effective capture pacing RR interval providing the effective capture pacing rate.

[0188] Embodiment Ex9: An implantable medical device according to any one of Embodiments Ex1 to Ex8, wherein the cardiac conduction system electrode is implantable in the ventricular septum to deliver cardiac conduction system pacing therapy.

[0189] Embodiment Ex10: An implantable medical device, comprising:

[0190] one or more implantable electrodes for sensing and pacing a patient's heart, wherein the one or more implantable electrodes include an electrode positionable proximate to a left ventricle of the patient's heart; and

[0191] A computing device comprising processing circuitry, the computing device being operably coupled to the one or more implanted electrodes, wherein the computing device is configured to:

[0192] determining an advance pacing delay to capture ventricular myocardium, wherein the advance pacing delay represents a period of time from delivery of a LV septal pacing pulse to a ventricular event; and

[0193] initiating delivery of LV septal pacing during atrial fibrillation using the electrode according to the advance pacing delay,

[0194] Wherein, in order to determine the advance pacing delay, the computing device is further configured to:

[0195] initiating delivery of a test LV septal pacing to capture the ventricular myocardium during atrial fibrillation using the electrode according to one or more parameters, wherein the one or more parameters include an atrioventricular (AV) delay that is shorter than an intrinsic AV delay;

[0196] monitoring a far-field electrogram using at least one of the one or more implanted electrodes and the one or more surface electrodes during the test LV septal pacing;

[0197] determining a fiducial point within the far-field electrogram; and

[0198] determining the advance pacing delay based on the reference point,

[0199] wherein the advance pacing delay is a delay period from delivery of a test LV septal pacing pulse of the test LV septal pacing to the reference point, and

[0200] Wherein the reference point is the maximum negative QRS deflection identified within the far-field electrogram.

[0201] Embodiment Ex11: A method, comprising:

[0202] Determining an advance pacing delay to capture a patient's cardiac conduction system, wherein the advance pacing delay represents a time period from delivery of a cardiac conduction system pacing pulse to a ventricular event; and delivering cardiac conduction system pacing during atrial fibrillation using a cardiac conduction system electrode positioned proximate to a portion of the patient's cardiac conduction system based on the advance pacing delay.

[0203] Embodiment Ex12: A method according to embodiment Ex11, wherein delivering cardiac conduction system pacing during atrial fibrillation using the cardiac conduction system electrode positioned proximate to the portion of the patient's cardiac conduction system according to the advance pacing delay includes: increasing the pacing rate of the cardiac conduction system pacing based on the advance pacing delay.

[0204] Embodiment Ex13: The method according to any one of Embodiments Ex11 to Ex12, wherein determining the advance pacing delay further comprises:

[0205] delivering test cardiac conduction system pacing during atrial fibrillation to capture the cardiac conduction system using the cardiac conduction system electrode positioned proximate the portion of the patient's cardiac conduction system according to one or more parameters including a pacing rate faster than an intrinsic rate and an atrioventricular (AV) delay shorter than an intrinsic AV delay;

[0206] monitoring far-field electrical activity using at least one of the one or more implanted electrodes and the one or more surface electrodes during delivery of the test cardiac conduction system pacing;

[0207] determining a reference point within the far-field electrical activity; and

[0208] The advance pacing delay is determined based on the reference point.

[0209] Embodiment Ex14: A method according to embodiment Ex13, wherein the advance pacing delay is a delay period from the delivery of a test cardiac conduction system pacing pulse of the test cardiac conduction system pacing to the reference point.

[0210] Embodiment Ex15: A method according to any one of embodiments Ex13 to Ex14, wherein the reference point is the earliest QRS deflection identified within the monitored far-field electrical activity after the test cardiac conduction system pacing pulse.

[0211] Embodiment Ex16: The method according to any one of embodiments Ex11 to Ex15, wherein determining the advance pacing delay further comprises:

[0212] delivering test cardiac conduction system pacing using the cardiac conduction system electrodes at a plurality of AV delays during a test period;

[0213] monitoring electrical activity using at least one of one or more implanted electrodes and one or more surface electrodes during delivery of test cardiac conduction system pacing at the plurality of AV delays during the test time period;

[0214] identifying a fused AV delay among the plurality of AV delays based on the monitored electrical activity, wherein the fused AV delay is the shortest AV delay in which pacing of the test cardiac conduction system results in fusion;

[0215] identifying a valid captured AV delay among the plurality of AV delays based on the monitored electrical activity, wherein the valid captured AV delay is a longest AV delay for which the test cardiac conduction system pacing effectively captures the patient's cardiac conduction system; and

[0216] The advance pacing delay is determined based on the fused AV delay and the effective captured AV delay.

[0217] Embodiment Ex17: The method according to any one of Embodiments Ex11 to Ex16, wherein determining the advance pacing delay further comprises:

[0218] determining that the patient is experiencing atrial fibrillation;

[0219] in response to determining that the patient is experiencing atrial fibrillation, delivering test cardiac conduction system pacing at a plurality of pacing rates over a test time period using the cardiac conduction system electrodes;

[0220] monitoring electrical activity using at least one of the one or more implanted electrodes or the one or more surface electrodes during delivery of test cardiac conduction system pacing at the plurality of pacing rates during the test time period;

[0221] identifying a fusion pacing rate among the plurality of pacing rates based on the monitored electrical activity, wherein the fusion pacing rate is the pacing rate at which pacing of the test cardiac conduction system results in fusion;

[0222] identifying an effective capture pacing rate among the plurality of pacing rates based on the monitored electrical activity, wherein the effective capture pacing rate is the slowest pacing rate at which the test cardiac conduction system pacing effectively captures the patient's cardiac conduction system; and

[0223] The advance pacing delay is determined based on the fused pacing rate and the effective captured pacing rate.

[0224] Embodiment Ex18: An implantable medical device according to embodiment Ex17, wherein the advance pacing delay is the difference between the fusion pacing RR interval provided by the fusion pacing rate and the effective capture pacing RR interval providing the effective capture pacing rate.

[0225] Embodiment Ex19: The method according to any one of Embodiments Ex11 to Ex18, wherein the cardiac conduction system electrode is implantable in the ventricular septum to deliver cardiac conduction system pacing therapy.

[0226] Embodiment Ex20: A method, comprising:

[0227] determining an advance pacing delay to capture a left ventricle of the patient, wherein the advance pacing delay represents a period of time from delivery of a pacing pulse to a ventricular event; and

[0228] delivering LV septal pacing during atrial fibrillation using an electrode positioned proximate to a left ventricle of the patient's heart according to the advance pacing delay,

[0229] Wherein determining the advance pacing delay further comprises:

[0230] delivering test LV septal pacing to capture ventricular myocardium during atrial fibrillation using the electrodes according to one or more parameters, wherein the one or more parameters include an atrioventricular (AV) delay that is shorter than an intrinsic AV delay;

[0231] monitoring a far-field electrogram using at least one of one or more implanted electrodes and one or more surface electrodes during said test LV septal pacing;

[0232] determining a fiducial point within the far-field electrogram; and

[0233] determining the advance pacing delay based on the reference point,

[0234] wherein the advance pacing delay is a delay period from delivery of a test LV septal pacing pulse of the test LV septal pacing to the reference point, and

[0235] Wherein the reference point is the maximum negative QRS deflection identified within the far-field electrogram.

[0236] 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.

[0237] In one or more examples, the described techniques may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, the functions may be stored as one or more instructions or codes on a computer-readable medium and executed by a hardware-based processing unit. 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).

[0238] 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 foregoing 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.

[0239] 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.

[0240] 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.

[0241] 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.

[0242] Numerical ranges expressed by endpoints include all values ​​contained in that range (e.g., 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, and 5) and any range within that range. As used herein, the term "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).

[0243] 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).

[0244] 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.

[0245] 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.

[0246] 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.

[0247] The term "and / or" means one or all of the listed elements or a combination of at least two of the listed elements.

[0248] 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 for sensing and pacing a patient's heart, wherein the one or more implantable electrodes include a cardiac conduction system electrode positionable proximate a portion of the patient's cardiac conduction system; and A computing device comprising processing circuitry, the computing device being operably coupled to the one or more implanted electrodes, wherein the computing device is configured to: determining an advance pacing delay to capture the cardiac conduction system, wherein the advance pacing delay represents a period of time from delivery of a cardiac conduction system pacing pulse to a ventricular event; and Delivery of cardiac conduction system pacing is initiated during atrial fibrillation using the cardiac conduction system electrodes based on the advance pacing delay.

2. The implantable medical device of claim 1 , wherein initiating delivery of cardiac conduction system pacing during atrial fibrillation using the cardiac conduction system electrode in accordance with the advance pacing delay comprises: A pacing rate of the cardiac conduction system pacing is increased based on the advance pacing delay.

3. The implantable medical device of claim 1 or 2, wherein to determine the advance pacing delay, the computing device is further configured to: initiating delivery of test cardiac conduction system pacing during atrial fibrillation using the cardiac conduction system electrodes to capture the cardiac conduction system according to one or more parameters, wherein the one or more parameters include a pacing rate faster than an intrinsic rate and an atrioventricular (AV) delay shorter than an intrinsic AV delay; monitoring far-field electrical activity using at least one of the one or more implanted electrodes and the one or more surface electrodes during delivery of the test cardiac conduction system pacing; determining a reference point within the far-field electrical activity; as well as The advance pacing delay is determined based on the reference point.

4. An implantable medical device according to claim 3, wherein the advance pacing delay is a delay period from the delivery of a test cardiac conduction system pacing pulse of the test cardiac conduction system pacer to the reference point.

5. An implantable medical device according to claim 3 or 4, wherein the reference point is the earliest QRS deflection identified within the monitored far-field electrical activity after a pacing pulse of the test cardiac conduction system.

6. The implantable medical device according to any one of claims 1 to 5, wherein to determine the advance pacing delay, the computing device is further configured to: initiating delivery of test cardiac conduction system pacing using the cardiac conduction system electrodes at a plurality of AV delays during a test period; monitoring electrical activity using at least one of the one or more implanted electrodes and the one or more surface electrodes during delivery of test cardiac conduction system pacing at the plurality of AV delays during the test time period; identifying a fused AV delay among the plurality of AV delays based on the monitored electrical activity, wherein the fused AV delay is the shortest AV delay in which pacing of the test cardiac conduction system results in fusion; identifying a valid captured AV delay among the plurality of AV delays based on the monitored electrical activity, wherein the valid captured AV delay is a longest AV delay for which the test cardiac conduction system pacing effectively captures the patient's cardiac conduction system; and The advance pacing delay is determined based on the fused AV delay and the effective captured AV delay.

7. The implantable medical device of any one of claims 1 to 6, wherein to determine the advance pacing delay, the computing device is further configured to: determining that the patient is experiencing atrial fibrillation; in response to determining that the patient is experiencing atrial fibrillation, initiating delivery of test cardiac conduction system pacing at a plurality of pacing rates over a test time period using the cardiac conduction system electrodes; monitoring electrical activity using at least one of the one or more implanted electrodes or the one or more surface electrodes during delivery of test cardiac conduction system pacing at the plurality of pacing rates during the test time period; identifying a fusion pacing rate among the plurality of pacing rates based on the monitored electrical activity, wherein the fusion pacing rate is the pacing rate at which pacing of the test cardiac conduction system induces fusion; identifying an effective capture pacing rate among the plurality of pacing rates based on the monitored electrical activity, wherein the effective capture pacing rate is the slowest pacing rate at which the test cardiac conduction system pacing effectively captures the patient's cardiac conduction system; as well as The advance pacing delay is determined based on the fused pacing rate and the effective captured pacing rate.

8. An implantable medical device according to any one of claims 1 to 7, wherein the advance pacing delay is the difference between the fusion pacing RR interval provided by the fusion pacing rate and the effective capture pacing RR interval providing the effective capture pacing rate.

9. A method, the method comprising, via a processing circuit of an implantable medical device: determining an advance pacing delay to capture the patient's cardiac conduction system, wherein the advance pacing delay represents a period of time from delivery of a cardiac conduction system pacing pulse to a ventricular event; and Instructions are provided for delivering cardiac conduction system pacing during atrial fibrillation using a cardiac conduction system electrode positioned proximate a portion of the patient's cardiac conduction system in accordance with the advance pacing delay.

10. The method of claim 9, wherein providing instructions for delivering cardiac conduction system pacing during atrial fibrillation using the cardiac conduction system electrode positioned proximate the portion of the patient's cardiac conduction system in accordance with the advance pacing delay comprises: A pacing rate of the cardiac conduction system pacing is increased based on the advance pacing delay.

11. The method of claim 9 or 10, wherein determining the advance pacing delay further comprises: delivering test cardiac conduction system pacing during atrial fibrillation to capture the cardiac conduction system using the cardiac conduction system electrode positioned proximate to the portion of the patient's cardiac conduction system according to one or more parameters, monitoring far-field electrical activity using at least one of the one or more implanted electrodes and one or more surface electrodes during the delivering of the test cardiac conduction system pacing, wherein the one or more parameters include a pacing rate faster than an intrinsic rate and an atrioventricular (AV) delay that is shorter than an intrinsic AV delay; determining a reference point within the far-field electrical activity; as well as The advance pacing delay is determined based on the reference point.

12. A method according to claim 11, wherein the advance pacing delay is a delay period from the delivery of a test cardiac conduction system pacing pulse of the test cardiac conduction system pacer to the reference point, and wherein the reference point is the earliest QRS deflection identified within the monitored far-field electrical activity after the test cardiac conduction system pacing pulse.

13. The method of any one of claims 9 to 12, wherein determining the advance pacing delay further comprises: monitoring electrical activity using at least one of the one or more implanted electrodes and the one or more surface electrodes during test cardiac conduction system pacing delivered using the cardiac conduction system electrodes at a plurality of AV delays during a test period; identifying a fused AV delay among the plurality of AV delays based on the monitored electrical activity, wherein the fused AV delay is the shortest AV delay in which pacing of the test cardiac conduction system results in fusion; identifying a valid captured AV delay among the plurality of AV delays based on the monitored electrical activity, wherein the valid captured AV delay is a longest AV delay for which the test cardiac conduction system pacing effectively captures the patient's cardiac conduction system; and The advance pacing delay is determined based on the fused AV delay and the effective captured AV delay.

14. The method of any one of claims 9 to 13, wherein determining the advance pacing delay further comprises: determining that the patient is experiencing atrial fibrillation; responsive to determining that the patient is experiencing atrial fibrillation, monitoring electrical activity using at least one of the one or more implanted electrodes or the one or more surface electrodes during delivery of test cardiac conduction system pacing at a plurality of pacing rates over a test time period using the cardiac conduction system electrodes; identifying a fusion pacing rate among the plurality of pacing rates based on the monitored electrical activity, wherein the fusion pacing rate is the pacing rate at which pacing of the test cardiac conduction system results in fusion; identifying an effective capture pacing rate among the plurality of pacing rates based on the monitored electrical activity, wherein the effective capture pacing rate is the slowest pacing rate at which the test cardiac conduction system pacing effectively captures the patient's cardiac conduction system; as well as The advance pacing delay is determined based on the fused pacing rate and the effective captured pacing rate.

15. An implantable medical device, comprising: one or more implantable electrodes for sensing and pacing a patient's heart, wherein the one or more implantable electrodes include an electrode positionable proximate to a left ventricle of the patient's heart; and A computing device comprising processing circuitry, the computing device being operably coupled to the one or more implanted electrodes, wherein the computing device is configured to: determining an advance pacing delay to capture ventricular myocardium, wherein the advance pacing delay represents a period of time from delivery of a LV septal pacing pulse to a ventricular event; and initiating delivery of LV septal pacing during atrial fibrillation using the electrode according to the advance pacing delay, Wherein, in order to determine the advance pacing delay, the computing device is further configured to: initiating delivery of a test LV septal pacing to capture the ventricular myocardium during atrial fibrillation using the electrode according to one or more parameters, wherein the one or more parameters include an atrioventricular (AV) delay that is shorter than an intrinsic AV delay; monitoring a far-field electrogram using at least one of the one or more implanted electrodes and the one or more surface electrodes during the test LV septal pacing; determining a reference point within the far-field electrogram; as well as determining the advance pacing delay based on the reference point, wherein the advance pacing delay is a delay period from delivery of a test LV septal pacing pulse of the test LV septal pacing to the reference point, and Wherein the reference point is the maximum negative QRS deflection identified within the far-field electrogram.

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