Determination of cardiac physiological conditions

Abstract

A treatment system comprises: an implantable medical device comprising one or more implantable electrodes (40, 42, 48, 50, 94); and a computing device (24) comprising processing circuitry and operably coupled to the one or more implantable electrodes (40, 42, 48, 50, 94). The one or more implantable electrodes (40, 42, 48, 50, 94) include an LBB electrode positionable adjacent a portion of a left bundle branch (LBB) of a patient and an RBB electrode positionable adjacent a portion of a right bundle branch (RBB) of the patient. The computing device (24) is configured to monitor electrical activity using the LBB electrode and the RBB electrode, detect electrical activity based on the monitored electrical activity indicative of left ventricular (LV) depolarization and right ventricular (RV) depolarization, determine a time difference value based on the detected electrical activity indicative of LV depolarization and the detected electrical activity indicative of RV depolarization, and determine a time difference value based on the determined time difference value. And determining whether there is a cardiac physiological condition based on the determined difference.

Description

[0001] The present disclosure generally relates to using electrogram signal analysis to determine one or more different cardiac physiological conditions, such as to update or modify pacing parameters to optimize pacing delivered to a patient according to the patient's needs. For example, instead of capturing cardiac myocardial tissue, pacing can be delivered to ensure capture of the cardiac conduction system and vice versa. More specifically, the present disclosure relates to electrogram signal analysis as opposed to electrocardiogram signal analysis, which can advantageously provide a more efficient means for determining cardiac physiological conditions or can advantageously eliminate the need to visit a clinic.

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

[0003] Over time, the left ventricle can become very inefficient at pumping blood to the body. For some patients, heart failure may develop where the heart becomes too weak to pump blood to the body. Heart failure can be a devastating diagnosis as, for example, fifty percent of heart failure patients have a life expectancy of five years or less. Another possible cause of heart failure is due to atrial fibrillation, which is an irregular and often very rapid heart rhythm or arrhythmia. During atrial fibrillation, the atria of the heart may beat out of sync with the ventricles of the heart due to the arrhythmia of the atria, which can cause blood clots in the heart and increase the risk of, for example, stroke or heart failure.

[0004] To avoid the potential development of heart failure, some physicians have considered alternative pacing methods involving the cardiac conduction system. Pacing the cardiac conduction system can conduct electrical pulses quickly (e.g., similar to a car traveling on a highway), while pacing cardiac muscle or myocardial tissue can conduct electrical pulses more slowly (e.g., similar to a car traveling on a muddy road).

[0005] The cardiac conduction system includes the sinoatrial node 1, atrial internodal tracts 2, 4, 5 (i.e., anterior internodal 2, middle internodal 4, and posterior internodal 5), atrioventricular node 3, bundle of His 13 (also known as the atrioventricular bundle or bundle of His), left bundle branch 8a, and right bundle branch 8b, as Figure 1 shown. The aortic arch 6 and Bachmann's bundle 7 are also shown in Figure 1 it. The sinoatrial node 1, 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 repetitively emits electrical impulses. The electrical impulses propagate through the muscle of the right atrium 26 to the left atrium 33 to cause synchronous contraction of the atria. The electrical impulses are also delivered via the atrial internodal tracts to the atrioventricular node 3 (the only connection between the atria and the ventricles). Conduction through the atrioventricular node or atrioventricular nodal tissue takes longer than through atrial tissue, which results in a delay between the onset of atrial contraction and the onset of ventricular contraction. The atrioventricular delay is the delay between atrial contraction and ventricular contraction, which allows the atria to empty blood into the ventricles. Then, concomitant with causing ventricular contraction via the branches of the bundle of His, the valves between the atria and the ventricles close. The bundle of His 13 is located in the membranous atrioventricular septum, near the tricuspid annulus. The bundle of His 13 divides into the left bundle branch 8a and the right bundle branch 8b and is formed by specialized fibers called "Purkinje fibers" 9. The Purkinje fibers 9 can be described as being able to rapidly conduct action potentials along the ventricular septum (VS), rapidly spread the depolarization wavefront through the remaining ventricular myocardium, and produce coordinated contraction of the ventricular muscle mass.

[0006] Additionally, some patients may suffer from cardiac physiological conditions, such as left bundle branch (LBB) or right bundle branch (RBB) block, in which electrical impulses cannot travel normally through the Purkinje fibers 9. This can lead to uncoordinated contraction of the right and left ventricles. In such cases, for example, during an attempt to coordinate ventricular contraction, cardiac conduction system pacing therapy may require higher amplitude pacing pulses or may require delivery of the pulses to a site in the cardiac conduction system distal (or farther along the cardiac conduction system away from the site) to the LBB block or RBB block. In some cases, instead of the cardiac conduction system, pacing the myocardial tissue of the heart may be more desirable. SUMMARY OF THE INVENTION

[0007] The present disclosure generally relates to using electrogram (EGM) signal analysis to determine one or more different cardiac physiological conditions, e.g., to update or modify pacing modes and parameters to optimize pacing delivered to a patient according to the patient's needs. LBB pacing is a physiological pacing method and this method requires LBB capture. RBB pacing is a physiological pacing method and this method requires RBB capture. In patients with LBB block or RBB block, electrical impulses do not propagate normally through the Purkinje fibers. In such cases, e.g., LBB pacing or RBB pacing may require a higher pulse output to overcome the conduction block, or the LBB or RBB may be paced at a location across or distal to the blocked site. Conversely, left ventricular (LV) or right ventricular (RV) septal pacing captures and paces at the respective septum, which is not part of the cardiac conduction system, and can provide another example of a pacing mode useful for patients with LBB block or RBB block.

[0008] It may be difficult to implant a lead close enough to the LBB to effectively pace the LBB, or the implanted LBB lead may shift over time, e.g., due to natural movement or due to injury, and thus LV septal pacing may occur. This is also true for RBB pacing that transfers to RV septal pacing. On the one hand, for patients with a normally functioning cardiac conduction system, in some cases, septal pacing may not be desirable. On the other hand, for patients with a non - normally functioning cardiac conduction system, in some cases (such as, e.g., when the LBB block or RBB block cannot be corrected or bypassed), septal pacing may be desirable. In other cases for patients with a non - normally functioning cardiac conduction system (such as, e.g., when the LBB block or RBB block can be corrected or bypassed), cardiac conduction system pacing is still desirable. The pacing mode can be selected based on the needs of the individual patient.

[0009] Specifically, exemplary devices and methods are described herein to use EGM signal analysis (as opposed to ECG signal analysis using an external device) to determine LBB function or RBB function, and to further determine various cardiac physiological conditions based on the EGM signal analysis, and to provide effective pacing therapy in response thereto. For example, as opposed to an ECG signal, the use of an EGM signal can advantageously provide a more efficient or effective analysis, provide timely modification of pacing parameters based on the patient's changing physiological conditions, resulting in more effective pacing, and can eliminate the need for the patient to visit a clinic to measure an ECG signal. EGM signal analysis can indicate, e.g., LBB block, RBB block, atrioventricular (AV) block, normal intrinsic conduction, and variations therebetween based on the difference between the measured onset of depolarization of the left and right ventricles.

[0010] In some examples, if the difference between the measured depolarization onsets of the RV is before the measured depolarization onset of the LV, LBB block may be determined. If the difference between the measured depolarization onsets of the LV is slightly before the measured depolarization onset of the RV (as determined using at least one threshold), intrinsic cardiac conduction may be determined. If the measured depolarization onset of the LV is significantly before the measured depolarization onset of the RV (as determined using an RBB threshold, which may or may not be the same value as the at least one threshold above), RBB block may be determined. AV block may be determined, for example, by calculating the time from an atrial pacing event to RV and LV depolarization prior to any determination, and if both depolarize at a time greater than an intrinsic AV conduction threshold, AV block may be determined.

[0011] The determination of various cardiac physiological conditions as described herein can be used to select and deliver a pacing configuration (e.g., cardiac conduction system pacing, myocardial pacing, or other pacing modes) that better meets the patient's needs, as described herein. For example, if a patient has LBB block, LBB pacing may need to be stronger (e.g., at a higher output voltage) to correct the block, or the site of the block may need to be bypassed, or myocardial pacing of the LV may be more effective than LBB pacing to control LV depolarization and ensure ventricular synchronization. As another example, if a patient has RBB block, RBB pacing may need to be stronger to correct the block, or the site of the block may need to be bypassed, or myocardial pacing of the RV may be more effective than RBB pacing to control RV depolarization and ensure ventricular synchronization. Additionally, selecting a pacing configuration to better meet the patient's needs can conserve battery life, prevent overpacing (which can cause, e.g., cardiomyopathy or atrial fibrillation), and provide an automated way to monitor and optimize cardiac pacing.

[0012] In one or more embodiments, illustrative devices and methods are described herein for periodically determining various cardiac physiological conditions in order to provide effective cardiac therapy to a patient over time. For example, for a patient receiving cardiac resynchronization therapy (CRT), an effective pacing mode may be desirable. Further, as the patient's physiological condition changes, such a pacing mode may need to be modified over time.

[0013] An exemplary treatment system may include an implantable medical device that includes a computing device. The computing device may also include processing circuitry and be operatively coupled to one or more implantable electrodes. The one or more implantable electrodes include an LBB electrode that can be positioned adjacent to a portion of a patient's LBB and an RBB electrode that can be positioned adjacent to a portion of the patient's RBB. The computing device is configured to: monitor electrical activity using the one or more implantable electrodes at the described locations. The computing device is further configured to: detect electrical activity based on the monitored electrical activity indicative of intrinsic LV depolarization and indicative of intrinsic RV depolarization. The computing device is further configured to: determine a time difference based on the detected electrical activity indicative of LV depolarization and the detected electrical activity indicative of RV depolarization. The computing device is further configured to: determine whether a cardiac physiological condition exists based on the determined difference.

[0014] An exemplary method may include: monitoring electrical activity using one or more implantable electrodes, the implantable electrodes including an LBB electrode positioned adjacent to a portion of a patient's LBB and an RBB electrode positioned adjacent to a portion of the patient's RBB. The method may further include: detecting electrical activity based on the monitored electrical activity indicative of LV depolarization and indicative of RV depolarization. The method may further include: determining a difference based on the detected electrical activity indicative of LV depolarization and the detected electrical activity indicative of RV depolarization. The method may further include: determining whether a cardiac physiological condition exists based on the determined difference.

[0015] An exemplary system may include a conduction system pacing lead. The conduction system pacing lead may include one or more implantable electrodes. The one or more implantable electrodes may include an LBB electrode that can be positioned adjacent to a portion of a patient's left bundle branch (LBB) and an RBB electrode that can be positioned adjacent to a portion of the patient's right bundle branch (RBB). The system may further include an implantable medical device. The device may include a computing device. The computing device may include processing circuitry. The computing device is operatively coupled to the one or more implantable electrodes. The computing device is configured to: monitor electrical activity using the one or more implantable electrodes. The computing device is further configured to: detect electrical activity based on the monitored electrical activity indicative of LV depolarization and indicative of RV depolarization. The computing device is further configured to: determine a difference based on the detected electrical activity indicative of LV depolarization and the detected electrical activity indicative of RV depolarization. The computing device is further configured to: determine whether a cardiac physiological condition exists based on the determined difference.

[0016] The foregoing summary is not intended to describe every embodiment or every implementation of the present disclosure. A more complete understanding will become apparent and appreciated by reference to the following detailed description and claims in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 is a schematic diagram of a patient's heart and conduction system.

[0018] Figure 2A is a conceptual diagram of an exemplary therapy system configured to provide cardiac conduction system pacing therapy to the left bundle branch and / or right bundle branch using a lead placed in the right ventricle.

[0019] Figure 2B shows Figure 2A a detailed conceptual diagram of the exemplary therapy system but including only two leads.

[0020] Figure 3A is a conceptual diagram of an exemplary therapy system configured to provide cardiac conduction system pacing therapy to the left bundle branch using a single lead placed in the right ventricle.

[0021] Figure 3B is Figure 2A a close-up view of the lead in the patient's heart.

[0022] Figure 4 illustrates Figures 2A to 3B a functional block diagram of an example of the configuration of an implantable medical device.

[0023] Figure 5 is a block diagram of an exemplary method for determining a cardiac physiological condition based on monitored electrical activity that can be utilized by the devices of FIGS. 2-3 and optionally pacing the heart based on the determined cardiac physiological condition.

[0024] Figure 6 determines Figure 5 a block diagram of an exemplary method for determining the difference in monitored electrical activity.

[0025] Figure 7 is a block diagram of an exemplary method for determining AV block, illustrating Figure 5 the determination of the cardiac physiological condition of the method.

[0026] Figure 8 is a block diagram of an exemplary method for determining LBB block, illustrating Figure 5 the determination of the cardiac physiological condition of the method.

[0027] Figure 9 is a block diagram of an exemplary method for determining RBB block, illustrating Figure 5 the determination of the cardiac physiological condition of the method.

[0028] Figure 10 is Figure 5 a block diagram of an exemplary method for determining the absence of a cardiac physiological condition of the method.

[0029] Figure 11 is a block diagram of another exemplary method for determining a cardiac physiological condition based on monitored electrical activity that can be utilized by the apparatus of FIGS. 2-3.

[0030] Figure 12 is an exemplary illustration of a portion of the heart and a medical lead utilized by the apparatus of FIGS. 2-3.

[0031] Figure 13 is another depiction over time of exemplary ECG and EGM signals, illustrating the determination of Figure 5 and Figure 8 for LBB block using the method of

[0032] Figure 14 is another depiction over time of exemplary ECG and EGM signals, illustrating the determination of Figure 5 and Figure 9 for RBB block using the method of

[0033] Figure 15 is another depiction over time of exemplary ECG and EGM signals, illustrating the determination of Figure 5 and Figure 10 for no cardiac physiological condition using the method of DETAILED DESCRIPTION

[0034] In the following detailed description of the 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 may be practiced. It is to be understood that other embodiments may be utilized and structural changes may be made without departing from (e.g., still falling within) the scope of the present disclosure presented herein.

[0035] Reference should be made to Figures 1 to 15 for a description of the 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 combinations of features set forth herein are not limited to the specific embodiments shown in the figures and / or described herein. Further, it will be recognized that the embodiments described herein may include many elements that are not necessarily shown to scale. Still further, it will be recognized that the timing of the processes herein and the size and shape of the various 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 preferred over other timings, one or more shapes and / or sizes, or element types.

[0036] Figure 1Depicts a schematic diagram of the heart 12, and FIGS. 2-3 depict conceptual diagrams showing exemplary treatment systems that can be used to provide treatment to a patient's heart 12. The patient is typically but not necessarily a human. As Figures 2A to 2B shown, the treatment system 10 can include an IMD 16 and a programmer 24 coupled to three leads 18, 20, 23. The IMD 16 can be, for example, an implantable pacemaker, cardioverter, and / or defibrillator that provides electrical pulses to the heart 12 via electrodes coupled to one or more of the leads 18, 20, 23. Other non-limiting examples of the IMD 16 include the following: a pacemaker with medical leads, an implantable cardioverter defibrillator (ICD), an intravascular device, a leadless pacing device (LPD), a subcutaneous ICD (S-ICD), and a subcutaneous medical device (e.g., a nerve stimulator, an insertable monitoring device, etc.).

[0037] The leads 18, 20, 23 can extend into the patient's heart 12 to sense the electrical activity of the heart 12 and / or deliver electrical stimulation to the heart 12. In Figure 2A the example shown, the right atrial (RA) lead 23 extends through one or more veins (not shown), the superior vena cava (not shown), and into the right atrium 26. The right atrial lead 23 can be positioned to place the electrodes 40, 42 near, adjacent to, on, within, or around the right atrium to sense electrocardiogram signals and pace the right atrial myocardium. The RA lead 23 is shown having an annular electrode 40 and a helical tip electrode 42, which can be selected from various bipolar pacing electrode pairs for pacing the right atrial myocardial tissue and sensing the right atrial epicardial electrocardiogram signals. One of the electrodes 40, 42 can be selected in combination with the IMD housing 60 or a coil electrode (62) to deliver unipolar right atrial myocardial pacing and / or sense unipolar atrial electrocardiogram signals.

[0038] The left ventricular coronary sinus lead 20 extends through one or more veins, the vena cava, the right atrium 26, and into the coronary sinus 30 to reach a region adjacent to the free wall of the left ventricle 32 of the heart 12. The left ventricular coronary sinus lead 20 can be positioned to place the electrodes 94a, 94b, 94c, 94d (collectively "94") epicardially along the left ventricular myocardium for sensing electrocardiogram signals and pacing the left ventricular myocardium. The left ventricular coronary sinus lead 20 is shown as a quadripolar lead carrying four electrodes 94a to 94d, which can be selected from various bipolar pacing electrode pairs for pacing the left ventricular myocardial tissue and sensing the left ventricular epicardial electrocardiogram signals. One of the electrodes 94 can be selected in combination with the IMD housing 60 or the coil electrode 64 for delivering unipolar left ventricular myocardial pacing and / or sensing unipolar ventricular electrocardiogram signals.

[0039] In one embodiment, a cardiac conduction system pacing therapy lead 18 (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, the right atrium 26, through the tricuspid valve and into the right ventricle 28 of the heart 12 to pace the cardiac conduction system (e.g., within the ventricular septum, near and / or in direct contact with the left bundle branch 8a, near and / or in direct contact with the right bundle branch 8b, near and / or in direct contact with the His bundle 13, etc.). In some embodiments, the cardiac conduction system pacing therapy lead 18 may be positioned within about 1 millimeter of a portion of the cardiac conduction system (e.g., the His bundle 13, the left bundle branch 8a, the right bundle branch 8b, etc.). The cardiac conduction system pacing therapy lead 18 may be positioned to locate electrodes 48, 50 (respectively) near, adjacent to, on, within, or around the RBB, LBB to sense electrocardiogram signals and pace the cardiac conduction system. The cardiac conduction system pacing therapy lead 18 is shown having an annular electrode 48 and a helical tip electrode 50, which annular electrode and helical tip electrode may be selected among various bipolar pacing electrode pairs for (respectively) pacing the RBB and LBB and for (respectively) sensing RBB electrocardiogram signals and LBB electrocardiogram signals. One of the electrodes 48, 50 may be selected in combination with the IMD housing 60 or a coil electrode (66) for delivering unipolar RBB and LBB pacing and / or sensing unipolar RBB and LBB electrocardiogram signals. In an alternative embodiment, the cardiac conduction system pacing therapy lead 18 is also used to pace the RA (shown in Figures 3A to 3B ), or to pace the RA in addition to the cardiac conduction system, such as in a dual lead configuration that does not include an RA lead 23.

[0040] An example of a cardiac conduction system pacing therapy lead (e.g., a His lead) may be SELECTSECURE TM 3830. For a description of SELECTSECURE TM 3830, see the Medtronic model SELECTSECURE TM 3830 manual (2013), which is incorporated herein by reference in its entirety. SELECTSECURE TM 3830 includes two conductors having lumens.

[0041] As used herein, cardiac conduction system pacing therapy refers to any technique configured to deliver pacing therapy (e.g., pacing pulses, electrical stimulation, etc.) to a cardiac conduction system that includes, for example, the His bundle 13, left bundle branch 8a, right bundle branch 8b, etc., in order to initiate activation. As used herein, the term "activation" refers to a sensed or paced event. For example, atrial activation may refer to an atrial sense or event (As) or an atrial pace or atrial pace artifact (Ap). As will be described herein, atrial sense may be detected or identified in one or more different signals monitored using one or more different devices or sensors located at one or more different locations. For example, atrial sense may be detected in a near-field electrical signal using an electrode located in the right atrium and a corresponding reference electrode (e.g., an electrode on the housing of an implantable medical device). Further, for example, atrial sense may be detected in a far-field electrical signal using an electrode located external to the right atrium (such as in the right ventricle or ventricular septum) and a corresponding reference electrode. Additionally, for example, atrial sense may be detected in a far-field signal using a mechanical cardiac activation sensor such as an accelerometer or microphone (e.g., a heart sound sensor) located external to the right atrium (such as in the right ventricle or ventricular septum) or in another part of the patient's body (e.g., within the can or housing of an IMD located external to the patient's heart). Similarly, ventricular activation may refer to a ventricular sense or event (Vs) or a ventricular pace or ventricular pace artifact (Vp), which may 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 may be detected. Specifically, the activation intervals may include a pace (Ap or Vp) to ventricular interval (left ventricular or right ventricular sense) or an atrial sense (As) to ventricular sense interval (left ventricular or right ventricular sense).

[0042] An exemplary IMD may be described as delivering one or both of conventional pacing therapy and cardiac conduction system pacing therapy. Conventional or traditional pacing therapy may be described as delivering pacing pulses into myocardial tissue that is not part of the cardiac conduction system of the patient's heart such that, for example, the pacing pulses trigger 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 prior to the myocardial tissue. For example, conventional pacing therapy may deliver pacing pulses directly into the muscular heart tissue (e.g., myocardial tissue) to be depolarized to provide cardiac contraction. For example, conventional left ventricular pacing therapy may utilize an implanted left ventricular coronary sinus lead 20 to 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 free wall of the left ventricle 32 of the heart 12 to deliver pacing pulses to the myocardial tissue of the free wall of the left ventricle 32.

[0043] An exemplary left ventricular lead 20 having a set of spaced electrodes is shown in U.S. Patent Publication WO2019 / 104174A1, filed May 4, 2012, by Ghosh et al., the entire disclosure of which is incorporated herein by reference. Exemplary electrodes on leads for forming pacing vectors are shown and described in U.S. Patent No. 8,355,784B2 and U.S. Patent No. 8,126,546, each of which is incorporated herein by reference in its entirety.

[0044] Additionally, pacing therapy leads 18, 20, 23 can be used to deliver left ventricular or left ventricular septal pacing to the ventricular septum. 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 a region adjacent to the septum of the left ventricle 32 of the heart 12.

[0045] Exemplary cardiac conduction system pacing therapy can be described, for example, in U.S. Patent Application Publication 2019 / 0111270A1, titled "His Bundle and Bundle Branch Pacing Adjustment," published on April 18, 2019, the entire disclosure of which is incorporated herein by reference. Exemplary left ventricular septal pacing can be described, for example, in U.S. Patent Application Serial No. 16 / 521,000, titled "AV Synchronous Septal Pacing," filed on July 24, 2019, the entire disclosure of which is incorporated herein by reference.

[0046] One or more elongated conductors of any of the leads 18, 20, 23 can extend through a hermetic feedthrough assembly and be within the insulating tubular member of the respective lead, and can electrically couple an electrical pulse generator (contained within a housing) to one or more electrodes, such as, for example, a ring electrode, a tip electrode, a helical electrode, etc. The conductors can be formed of one or more wire leads in a coiled or cabled configuration, including, for example, an MP35N alloy known to those skilled in the art, and the insulating tubular member can be any suitable medical-grade polymer, such as polyurethane, silicone rubber, or blends thereof. According to one or more exemplary embodiments, the flexible lead body can extend a predetermined length (e.g., from about 10 centimeters (cm) to about 20 cm, or from about 15 cm to 20 cm) from the proximal end to the distal end. The lead body can be sized to be less than about 7 French (FR), but is typically in the range of about 3 FR to 4 FR. In one or more embodiments, a lead body sized from about 2 FR to about 3 FR is employed.

[0047] Cardiac conduction system pacing may include at least one of His bundle pacing, LBB pacing, and RBB pacing. Bundle branch pacing may bypass pathological regions and may have a low and stable pacing threshold. In some embodiments, only one of the left or right bundle branches may be paced using one or more pacing leads. In another embodiment, both bundle branches may be paced simultaneously (e.g., dual bundle branch pacing), which may mimic the propagation of intrinsic activation via the His-Purkinje conduction system. For example, the paced activation may propagate to both ventricles via both bundle branches for synchronous contraction. On the other hand, His bundle pacing typically paces the His bundle near the bundle branches. In some embodiments, the IMD 16 may be coupled to one, two, or more electrodes located in one or more of the bundle branches configured for bundle branch pacing.

[0048] In some embodiments, the IMD 16 may be an intracardiac pacemaker or a leadless pacing device (LPD) configured to pace one or more portions of the cardiac conduction system, such as one or two of the bundle branches. As used herein, "leadless" refers to a device that does not have leads extending out of the heart 12. In other words, the leads of a leadless device may not extend from the outside of the heart to the inside of the heart. Some leadless devices may be introduced through a vein, but once implanted, the leadless device may not have or may not include any transvenous leads and may be configured to provide cardiac therapy without using any transvenous leads. In one or more embodiments, an exemplary LPD for bundle pacing does not use a lead to operably connect to an electrode disposed near the septum when the housing of the device is positioned in the atrium. The leadless electrode may be coupled to the housing of the medical device without using a lead between the electrode and the housing.

[0049] The IMD 16 may sense electrical signals associated with depolarization and repolarization of the heart 12 via various electrodes shown as Figure 2A coupled to at least one of the leads 18, 20, 23. In some examples, the IMD 16 provides pacing pulses to the heart 12 based on electrical signals sensed within the heart 12. The configuration of the electrodes of the IMD 16 for sensing and pacing may be unipolar or bipolar.

[0050] The IMD 16 may also provide defibrillation therapy and / or cardioversion therapy via electrodes located on at least one of the leads 18, 20, 23. For example, the IMD 16 may detect atrial arrhythmias of the heart 12, such as atrial fibrillation of the atria 26, 33, and then deliver defibrillation therapy to the heart 12 in the form of electrical pulses. The IMD 16 may also detect ventricular arrhythmias of the heart 12, such as ventricular fibrillation of the ventricles 28, 32, and then deliver defibrillation therapy to the heart 12 in the form of electrical pulses. In some examples, the IMD 16 may be programmed to deliver a treatment progression, e.g., pulses with increasing energy levels, until fibrillation of the heart 12 ceases. The IMD 16 may employ one or more fibrillation detection techniques known in the art to detect fibrillation.

[0051] In some examples, as Figures 2A to 2B shown, the programmer 24 may be a handheld computing device or a computer workstation or a mobile phone. The programmer 24 may include a user interface that receives input from a user. The user interface may include, for example, a keypad and a display, which may 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. The programmer 24 may additionally or alternatively include a peripheral pointing device (such as a mouse) via which the user may interact with the user interface. In some embodiments, the display of the programmer 24 may include a touchscreen display, and the user may interact with the programmer 24 via the display. Through the graphical user interface on the programmer 24, the user may configure one or more pacing therapies, select one or more pacing modes, etc.

[0052] Additionally, various pacing settings may be adjusted or configured based on various sensed signals. For example, various near-field signals and far-field signals may be sensed by one or more of the electrodes coupled to the IMD 16 and / or other devices operatively coupled thereto. For example, the right ventricular depolarization interval and the left ventricular depolarization interval may be monitored or measured within the near-field signal or the far-field signal and then used to adjust, configure, and select cardiac conduction system pacing therapy. Further, for example, the QRS morphology (e.g., QRS peak, various QRS intervals) may be monitored or measured within the near-field signal or the far-field signal and then used to adjust, configure, and select cardiac conduction system pacing therapy. Still further, for example, one or more of the right ventricular depolarization and left ventricular depolarization interval consistency and QRS morphology consistency may be monitored or measured within the near-field signal or the far-field signal and then used to adjust, configure, and select cardiac conduction system pacing therapy.

[0053] The exemplary treatment systems described herein (such as IMD 16) can be used to deliver cardiac conduction system pacing therapies according to a variety of different modes (such as, for example, an inhibited pacing mode, a ventricular fusion pacing mode, an atrioventricular synchronous pacing mode, an atrial fibrillation pacing mode, etc.).

[0054] The ventricular fusion pacing mode can be configured to deliver a cardiac conduction system pacing therapy to provide effective ventricular fusion. Effective ventricular fusion can be described as synchronizing the timing of left ventricular activation with the activation on the right ventricle. For example, in a fusion pacing configuration, the medical device can deliver one or more pacing pulses in order to pre-excite the left ventricle and synchronize the depolarization of the left ventricle with the depolarization of the earlier contracting right ventricle. The ventricular activation of the left ventricle may “fuse” (or “merge”) with the ventricular activation of the right ventricle, which is attributed to the intrinsic conduction of the heart. In this way, the intrinsic and pacing-induced wavefronts of excitation can fuse together, thereby resynchronizing the depolarization of the left ventricle with the depolarization of the right ventricle.

[0055] For patients experiencing LBB block, the selected pacing mode (such as, for example, an inhibited pacing mode, a ventricular fusion pacing mode, etc.) can also be configured to provide LBB pacing pulses at a high enough voltage output to correct the LBB block, or can be configured to provide LBB pacing pulses at a location distal to the block so that the block is bypassed, or can be configured to stop any ongoing delivery of cardiac conduction system pacing through the LBB and deliver left ventricular septal pacing using an implanted electrode. For patients experiencing RBB block, the selected pacing mode (such as, for example, an inhibited pacing mode, a ventricular fusion pacing mode, etc.) can also be configured to provide RBB pacing pulses at a high enough voltage output to correct the RBB block, or can be configured to provide RBB pacing pulses at a location distal to the block so that the block is bypassed, or can be configured to stop any ongoing delivery of cardiac conduction system pacing through the RBB and deliver right ventricular septal pacing using an implanted electrode. These effectively switch the mode from cardiac conduction system pacing to more traditional myocardial pacing in an effort to achieve ventricular fusion.

[0056] As used herein, the term "far-field" electrical signal refers to the result of measuring cardiac activity using a sensor (such as an electrode) positioned outside the region of interest. For example, a far-field electrical signal representing the electrical activity of a region of interest of a patient's heart can be measured from an electrode positioned in an adjacent chamber (i.e., a chamber different from the chamber of interest that is adjacent to or near the chamber of interest). More specifically, for example, atrial electrical activity representing depolarization of one or both atria or electrical activity originating from one or more bilateral atria can be monitored in a far-field electrical signal that is measured using an electrode positioned outside the right atrium (such as in the right ventricle or left ventricle) or in the ventricular septum. As used herein, the term "near-field" electrical signal refers to the result of measuring cardiac activity using a sensor (such as an electrode) positioned near the region of interest. For example, an electrical signal measured using an electrode positioned on the left side of a patient's ventricular septum is an example of a near-field electrical signal of the patient's LV.

[0057] P-wave timing is the time at which the P wave is detected. Typically, P-wave timing includes using the maximum first derivative of the rising edge of the P wave (or the time of the maximum P-wave value). P-wave timing is also used in the device marker channel to indicate the P-wave time or atrial activation time. P-wave timing can be determined using near-field signals obtained from sensors (such as electrodes, accelerometers, heart sound sensors, etc.) positioned in the atrium (e.g., the right atrium) and / or far-field near-field signals obtained from sensors (such as electrodes, accelerometers, heart sound sensors, etc.) positioned outside the atrium (e.g., the right atrium), such as in the right ventricle and / or the ventricular septum.

[0058] R-wave timing is the time at which the QRS complex is detected. Typically, R-wave timing includes using the maximum first derivative of the rising edge of the R wave (or the time of the 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.

[0059] A user (such as a physician, technician, or other clinician) can interact with the programmer 24 to communicate with the IMD 16. For example, the user can interact with the programmer 24 to retrieve physiological or diagnostic information from the IMD 16. Additionally, the user can also interact with the programmer 24 to program the IMD 16, for example, to select values for the operating parameters of the IMD 16. The IMD 16 and the programmer 24 can communicate via wireless communication using any technique known in the art. Examples of communication techniques can include, for example, low-frequency or radio frequency (RF) telemetry, but other techniques are also contemplated. In some examples, the programmer 24 can include a programming head that can be placed adjacent to the patient's body near the IMD 16 implantation site to improve the quality or security of the communication between the IMD 16 and the programmer 24.

[0060] The triple-chamber IMD 16 can be used for cardiac resynchronization therapy and defibrillation or cardioversion therapy (CRT-D). Leads 18, 20, 23 can be electrically coupled to a stimulation generator, a sensing module, or other modules of the IMD 16 via a connector block 34. In some examples, the proximal ends of leads 18, 20, 23 can include electrical contacts that are electrically coupled to corresponding electrical contacts within the connector block 34. Additionally, in some examples, leads 18, 20, 23 can be mechanically coupled to the connector block 34 by means of set screws, connection pins, or another suitable mechanical coupling mechanism.

[0061] Although the cardiac conduction system pacing lead 18 is shown and described as being placed in the RV along the ventricular septum Figure 2A , Figure 2B , Figure 3A and Figure 3B are shown and described as being placed in the RV along the ventricular septum, in other examples, the cardiac conduction system pacing lead 18 can be placed in the right atrium within the triangle of the Koch area (not shown), where the corresponding electrodes 48, 50 tunnel through septal tissue to be positioned near the RBB and LBB, respectively. In such examples, the system may not include a lead positioned within the RV, but still obtain the benefits of LBB pacing and sensing or RBB pacing and sensing as described herein. Additionally or alternatively, the system in such examples can include additional leads or electrodes (e.g., RA lead 23 or electrodes 40, 42) positioned in the RA, which are configured to pace the RA and can be different from the cardiac conduction system pacing lead 18 or the corresponding LBB and RBB electrodes.

[0062] Each of the leads 18, 20, 23 includes an elongated insulated lead body that can carry any number of conductors. In the illustrated example, an optional pressure sensor 38 and bipolar electrodes 48 and 50 are positioned near the distal end of the cardiac conduction system pacing lead 18. The pressure sensor 38 can respond to the absolute pressure inside the RV, or can be positioned in other regions of the heart 12 or within or near the patient's cardiovascular system elsewhere to monitor cardiovascular pressures associated with the mechanical contraction of the heart. Additionally, in some examples, the pressure sensor 38 can be an integrated device implanted within the heart 12 and wirelessly corresponding to the IMD 16. Additionally, bipolar electrodes 94a to 94d (collectively referred to by reference numeral 94) are positioned near the distal end of the left ventricular lead 20, and bipolar electrodes 40 and 42 are positioned near the distal end of the RA lead 23. Electrodes 48, 50 can be used for pacing and / or sensing of cardiac conduction system tissue (e.g., His bundle tissue or bundle branch tissue).

[0063] The electrodes 40, 94a to 94c, and 48 may take the form of annular electrodes, and the electrodes 42, 94d, and 50 may take the form of extendable and / or fixed helical tip electrodes respectively mounted within insulating electrode heads 52, 54, and 56. Each of the electrodes 40, 42, 94, 48, and 50 may be electrically coupled to a respective one of the coil conductors within the lead body of its associated lead 23, 20, 18, and thereby to a respective one of the electrical contacts at the proximal end of the leads 23, 20, 18.

[0064] The electrodes 40, 42, 94, 48, and 50 may sense electrical signals associated with depolarization and repolarization of the heart 12. The electrical signals are conducted via the respective leads 23, 20, 18 to the IMD 16. In some examples, the IMD 16 also delivers pacing pulses via the electrodes 40, 42, 94, 48, 50 to cause depolarization of the cardiac tissue of the heart 12. In some examples, as Figure 2B illustrated, the IMD 16 may include one or more can electrodes (such as can electrode 58), which may be integrally formed with or otherwise coupled to the outer surface of the hermetic can 60 of the IMD 16. In some examples, the can electrode 58 may be defined by a non-insulating portion of the outward-facing portion of the can 60 of the IMD 16. Other separations between the insulating and non-insulating portions of the can 60 may be used to define two or more can electrodes. In some examples, the can electrode 58 substantially comprises the entirety of the can 60. Any one of the electrodes 40, 42, 94, 48, 50 may be used in combination with the can electrode 58 for unipolar sensing or pacing, or for bipolar sensing with two electrodes in the same pacing lead. In one or more embodiments, the can 60 may enclose a stimulation generator that produces cardiac pacing pulses and defibrillation or cardioversion shocks (see Figure 4 ), and a sensing module for monitoring the patient's heart rhythm.

[0065] The leads 23, 20, 18 may also respectively include elongated electrodes 62, 64, 66 (shown in Figure 2A ) that may take the form of coils. The IMD 16 may deliver defibrillation shocks to the heart 12 via any combination of the elongated electrodes 62, 64, 66 and the can electrode 58. The electrodes 58, 62, 64, 66 may also be used to deliver cardioversion pulses to the heart 12. The electrodes 62, 64, 66 may be made of any suitable conductive material (such as but not limited to platinum, platinum alloy, or other materials known to be used in implantable defibrillation electrodes).

[0066] The elongated electrode can be selected, along with either a lead-based tip or ring electrode, in a unipolar electrode vector to sense a unipolar electrocardiogram signal for analyzing and determining ventricular conduction status. In some cases, the elongated electrode can be used with the housing 60 to sense far-field electrocardiogram signals for determining atrial depolarization or activation, etc. The pressure sensor 38 can be coupled to one or more coil conductors within the lead 18.

[0067] Figures 2C through Figure 3B is a conceptual diagram illustrating additional examples of a dual-chamber therapy system 70 and a single-chamber therapy system 71. The therapy system 70 is similar to Figure 2A therapy system 10 but includes two leads 18, 23 instead of three leads. The therapy system 70 can utilize an IMD 16 configured to deliver or perform dual-chamber pacing. The leads 18, 23 are implanted within the RV and RA to pace one or more portions of the cardiac conduction system (such as the His bundle or one or both bundle branches) and the RA, respectively. The therapy system 71 is similar to Figure 2A therapy system 10 but includes a single cardiac conduction system pacing lead 18 instead of three leads. The therapy system 71 can utilize an IMD 16 configured to deliver or perform single-chamber pacing. The cardiac conduction system pacing lead 18 is implanted within the RV to pace one or more portions of the cardiac conduction system, such as one or both bundle branches.

[0068] The cardiac conduction system pacing lead 18 can include an electrode 50 in the form of a helix (also referred to as a helical electrode) that can be positioned proximate to, adjacent to, or within a region or portion of the cardiac conduction system (such as, for example, the ventricular septum, Koch's triangle, His bundle, left bundle branch tissue, and / or right bundle branch tissue). The cardiac conduction system pacing lead 18 can be configured as a bipolar lead for use with a pacemaker device, a CRT-P device, or a CRT-ICD.

[0069] Figures 3A to 3B Shows the patient's heart 12 with a cardiac conduction system pacing lead 18 implanted to deliver bundle branch pacing according to one example of the single-chamber therapy system 71. The cardiac conduction system therapy lead 18 is positioned through the tricuspid valve or into the RV and implanted into the ventricular septum, for example, approximately 1 centimeter to 2 centimeters in the apical direction away from the RA (as Figures 2A to 2B illustrated). Figure 3B is Figure 3AClose-up view of the cardiac conduction system therapy lead 18 in the patient's heart 12. In some embodiments, the cardiac conduction system therapy lead 18 can be the only lead implanted in the heart 12. In other embodiments as discussed herein, there can be additional leads in addition to the cardiac conduction system therapy lead 18 implanted in the heart 12. One or more implantable electrodes of the cardiac conduction system therapy lead 18 can include pacing electrodes capable of being implanted close to the cardiac conduction system for delivering cardiac conduction system pacing therapy.

[0070] As illustrated, the cardiac conduction system pacing therapy lead 18 is implanted from the RV towards the LV into the interventricular septum or ventricular septum. The cardiac conduction system pacing therapy lead 18 does not pierce the LV wall or extend into the LV cavity. Electrodes 48 and 50 can be disposed on the distal end portion of the cardiac conduction system pacing therapy lead 18, as discussed herein at least with respect to Figure 2A that which is discussed. The cardiac conduction system pacing therapy lead 18 can also be described as an axis. Electrodes 48 and 50 can be the same as or similar to electrodes 48 and electrode 50 as Figure 2A shown, and electrode 48 is configured to sense or pace the right bundle branch and electrode 50 is configured to sense or pace the left bundle branch, for example, during biventricular pacing. Thus, electrode 48 can be implanted near the right bundle branch 8b, and electrode 50 can be implanted near the left bundle branch 8a. Electrode 50 can be implanted towards the left side of the patient's ventricular septum. Electrode 48 can be implanted towards the right side of the patient's ventricular septum. In one embodiment, electrode 50 can be a helical electrode, and electrode 48 can be a ring electrode.

[0071] During biventricular pacing, both electrodes 48 and 50 can each deliver pulses to effect synchronous activation or excitation of the right bundle branch 8b and the left bundle branch 8a, which can result in synchronous activation of the RV and LV. In some embodiments, the pulses can be delivered simultaneously to effect synchronization. In other embodiments, the delivery of the pulses can be delayed to effect synchronization.

[0072] Although the illustrated cardiac conduction system pacing therapy lead 18 is configured for biventricular pacing using electrodes 48, 50, it should be understood that the cardiac conduction system pacing therapy lead 18 or a lead similar thereto is considered herein to include only one of electrodes 48 and electrode 50, and is thus configured to deliver cardiac conduction system pacing therapy to only one of the right bundle branch and the left bundle branch. In an alternative embodiment, both electrodes 48 and 50 can be located on the cardiac conduction system pacing therapy lead 18, but the IMD 16 can use only one of electrodes 48, 50 to pace only one bundle branch.

[0073] Additionally, the cardiac conduction system pacing therapy lead 18 may include an RA electrode 75 disposed proximally to the electrodes 48, 50 along the cardiac conduction system pacing therapy lead 18. The RA electrode 75 may be positioned in or near the RA and may serve as an anode for cathodal pulses from the electrode 48 and / or the electrode 50. Further, the RA electrode 75 may provide atrial sensing to sense, for example, atrial depolarization or activation, atrial fibrillation, etc. Although the illustrated cardiac conduction system pacing therapy lead 18 includes the RA electrode 75, it should be understood that the cardiac conduction system pacing therapy lead 18 may not include the RA electrode 75 and instead may include only one or both of the electrodes 48 and 50.

[0074] When the cardiac conduction system pacing therapy lead 18 is positioned for delivering bundle branch pacing to one or both bundle branches, the cardiac conduction system pacing therapy may be combined with conventional ventricular myocardial pacing of the left ventricle using the coronary sinus lead 20 to correct left ventricular conduction delay and achieve electrical and mechanical synchronization of the left and right ventricles. Thus, in some examples, one or more processors, one or more processing circuits, or computing devices of the IMD 16 may select cardiac conduction system pacing therapy plus conventional left ventricular myocardial pacing therapy, which includes, for example, single bundle branch pacing or dual bundle branch pacing (e.g., using the cardiac conduction system pacing therapy lead 18) combined with left ventricular myocardial pacing using the coronary sinus lead 20.

[0075] The configurations of the therapy systems 10, 70, and 71 illustrated in FIGS. 2-3 are merely examples. In other examples, the therapy system may include epicardial leads and / or patch electrodes to replace or supplement the transvenous leads 18, 20, 23 illustrated in FIGS. 2-3, or other configurations shown or described herein or incorporated by reference. Further, the IMD 16 need not be implanted within the patient. Thus, it should be understood that the exemplary therapy systems described herein may include any suitable number of leads coupled to the IMD 16, and each of these leads may extend to any location within or near the heart 12. For example, the exemplary therapy system may include three transvenous leads positioned as Figure 2A illustrated, a single transvenous lead positioned as Figures 3A to 3B illustrated, or two transvenous leads positioned as Figure 2B illustrated.

[0076] Figure 4 is a functional block diagram of an example configuration of the IMD 16. Figure 4The operation of the IMD 16 can be substantially similar to that of the IMD 16. The IMD 16 includes a processor 80, a memory 82, a stimulation generator 84 (e.g., an electrical pulse generator or a signal generation 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, can be housed within the housing of the IMD 16 (e.g., housed within the housing of a pacemaker). The telemetry module 88, the sensing module 86, or both the telemetry module 88 and the sensing module 86 can be included in a communication interface. The memory 82 includes computer-readable instructions that, when executed by the processor 80, cause the IMD 16 and the processor 80 to perform various functions attributed to the IMD 16 and the processor 80 herein. The memory 82 can include any volatile, non-volatile, magnetic, optical, or dielectric medium, such as random access memory (RAM), read-only memory (ROM), non-volatile RAM (NVRAM), electrically erasable programmable ROM (EEPROM), flash memory, or any other digital medium.

[0077] The processor 80 can 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 equivalent discrete or integrated logic circuitry. In some examples, the processor 80 can include multiple components (such as any combination of one or more microprocessors, one or more controllers, one or more DSPs, one or more ASICs, or one or more FPGAs) and other discrete or integrated logic circuitry. The functions attributed to the processor 80 herein can be embodied as software, firmware, hardware, or any combination thereof. The processor 80 controls the stimulation generator 84 to select a therapy mode (e.g., select one or more of an inhibition pacing mode, a ventricular fusion pacing mode, an atrioventricular synchronous pacing mode, an atrial fibrillation pacing mode, etc.), and delivers stimulation therapy to the heart 12 based on the selected pacing mode and various sensed parameters (such as atrial depolarization or activation, ventricular atrial depolarization or activation, heart rate, P-wave to R-wave interval, etc.) that 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 therapy programs and therapy modes.

[0078] In some embodiments, the cardiac conduction system pacing lead 18 can be operatively coupled to an electrode 75 that can be used to monitor or pace the RA. The stimulation generator 84 can be electrically coupled to the electrodes 40, 42, 94, 48, 50, 58, 75, 62, 64, and 66, for example, via the conductors of the respective leads 23, 20, 18 or, in the case of the can electrode 58, via electrical conductors disposed within the housing 60 of the IMD 16. The stimulation generator 84 can be configured to generate and deliver electrical stimulation therapy to the heart 12. For example, the stimulation generator 84 can deliver defibrillation shocks to the heart 12 via at least two of the electrodes 58, 62, 64, 66. The stimulation generator 84 can deliver pacing pulses via the ring electrodes 40, 94, 48 respectively coupled to the leads 23, 20, 18 and / or via the helical electrodes 42, 94, 50 of the leads 23, 20, or 18 respectively. In various embodiments, cardiac conduction system pacing therapy can be delivered via the cardiac conduction system pacing lead 18 connected to the atrial, right ventricular, or left ventricular connection port of the connector block 34. In some examples, the stimulation generator 84 delivers pacing, cardioversion, or defibrillation stimulation in the form of electrical pulses. In other examples, the stimulation generator 84 can deliver one or more of these types of stimulation in the form of other signals, such as sine waves, square waves, or other substantially continuous time signals.

[0079] The stimulation generator 84 can include a switching module, and the processor 80 can use the switching module to select, for example via the data / address bus, which of the available electrodes to use for delivering defibrillation shocks or pacing pulses. The switching module can include a switch array, a switch matrix, a multiplexer, or any other type of switching device suitable for selectively coupling the stimulation energy to the selected electrode.

[0080] The sensing module 86 monitors signals from at least one of the electrodes 40, 42, 94, 48, 50, 58, 75, 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 can also include a switching module for selecting which of the available electrodes to use for sensing cardiac activity. In some examples, the processor 80 can select, via the switching module within the sensing module 86, for example by providing a signal via the data / address bus, the electrode that serves as the sensing electrode. In some examples, the sensing module 86 includes one or more sensing channels, and each of the sensing channels can include an amplifier. In response to a signal from the processor 80, the switching module can couple the output from the selected electrode to one of the sensing channels.

[0081] In some examples, one channel of the sensing module 86 may include an R-wave amplifier that receives signals from electrodes 94 that are used for pacing and sensing in the LV of the heart 12. Another channel may include another R-wave amplifier that receives signals from electrodes 48, 50 that are used for pacing and sensing in the RV of the heart 12. In some examples, the R-wave amplifier may take the form of an automatic gain control amplifier that provides an adjustable sensing threshold based on the R-wave amplitude of the measured heart rate.

[0082] Additionally, in some examples, one channel of the sensing module 86 may include a P-wave amplifier that receives signals from electrodes 40, 42 that are used for pacing and sensing in the RA 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, titled "APPARATUS FOR MONITORING ELECTRICAL PHYSIOLOGIC SIGNALS," issued to Keimel et al. on June 2, 1992, which is hereby incorporated by reference in its entirety. Other amplifiers may also be used. Additionally, in some examples, one or more of the sensing channels in the sensing module 86 may be selectively coupled to the can electrode 58 or the elongated electrodes 62, 64, or 66, either together with or in place of one or more of the electrodes 40, 42, 94, 48, or 50, for example, for unipolar sensing of R-waves or P-waves in any of the chambers 26, 28, or 32 of the heart 12.

[0083] In some examples, the sensing module 86 includes a channel that includes an amplifier having a relatively wider passband than the R-wave amplifier or the P-wave amplifier or a high-resolution amplifier having a relatively narrow passband for recording His bundle or bundle branch potentials. Signals from the selected sensing electrodes that are selected for coupling to this wideband amplifier may be provided to a multiplexer and thereafter converted to a multi-bit digital signal by an analog-to-digital converter for storage as an electrogram (EGM) in the memory 82. 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 the numerous signal processing methods known in the art.

[0084] If the IMD 16 is configured to generate and deliver pacing pulses to the heart 12, the processor 80 may include a pacemaker timing and control module, which may be embodied as hardware, firmware, software, or any combination thereof. The pacemaker timing and control module may include dedicated hardware circuitry (such as an ASIC) separate from other components of the processor 80, such as a microprocessor, or a software module executed by a component of the processor 80 that may be a microprocessor or an ASIC. The pacemaker timing and control module may include a programmable counter that controls the 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 foregoing 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 being paced, the second letter may indicate the chamber in which an electrical signal is sensed, and the third letter may indicate the chamber in which a response to the sensed signal is provided.

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

[0086] During pacing, the escape interval counter within the pacemaker timing / control module may be reset upon sensing of R waves and P waves. The stimulus 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, 94, 48, 50, 58, 75, 62, or 66 in a chamber of the heart 12 suitable for delivering bipolar or unipolar pacing pulses. The processor 80 may reset the escape interval counter when pacing pulses are generated by the stimulus generator 84, and thereby control the basic timing of the cardiac pacing function, including anti-tachyarrhythmia pacing.

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

[0088] The telemetry module 88 includes any suitable hardware, firmware, software, or any combination thereof for communicating with another device, such as a programmer 24. Under the control of the processor 80, the telemetry module 88 may receive downlink telemetry from the programmer 24 and transmit uplink telemetry to the programmer by means of an antenna that may be internal and / or external. The processor 80 may provide, for example, via an address / data bus, data to be uplink-transmitted to the programmer 24 and control signals for the telemetry circuitry within the telemetry module 88. In some examples, the telemetry module 88 may provide received data to the processor 80 via a multiplexer.

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

[0090] The exemplary systems, devices, and methods described herein may provide adaptive cardiac conduction system pacing therapy that may select a suitable cardiac conduction system pacing therapy mode based on one or more conditions or parameters measured from a patient.

[0091] The exemplary devices and methods described herein may provide and use monitored electrical activity (e.g., EGM, etc.) to determine various cardiac physiological conditions to provide an effective pacing mode for cardiac therapy, such as, for example, resynchronization therapy (CRT), biventricular pacing, LBB pacing (with or without atrial pacing), LV septal pacing, LBB block mode pacing; RBB pacing, RV septal pacing, RBB block mode pacing, etc. Further, the monitored electrical activity may be used to determine the difference in the monitored electrical activity indicative of LV and RV depolarization, which in turn may be used to determine various cardiac physiological conditions. As will be further described herein, the electrical activity of the heart may be monitored for specific regions of the heart, such as specific chambers (e.g., RV, LV), and may be acquired using various devices (e.g., EGM) as described herein.

[0092] If the determined time difference from at least one of (Ap) and (As) to LV depolarization is higher than the AV conduction threshold and the determined time difference from at least one of (Ap) and (As) to RV depolarization is higher than the AV conduction threshold, this may indicate AV block. If AV block is not determined, the device, system, and method may continue to determine other cardiac physiological conditions. If AV block is determined, the device, system, and method may or may not continue to determine other cardiac physiological conditions as discussed herein.

[0093] For example, the difference (of the monitored electrical activity indicating LV and RV depolarization) may be determined by analyzing the monitored electrical activity. In one embodiment, the monitored electrical activity may include one or more EGM signals monitored from the RBB and LBB as described herein. The difference may be determined or measured as the time difference between a reference point of the electrical activity monitored using an electrode such as the LBB electrode 50 indicating LV depolarization and a reference point of the electrical activity monitored using an electrode such as the RBB electrode 48 indicating RV depolarization. For example, the monitored electrical activity indicating LV depolarization may be determined or measured as the time point when the EGM signal measured using the LBB electrode intersects the isoelectric line before the main QRS waveform or morphology. The monitored electrical activity indicating RV depolarization may be determined or as the time point when the EGM signal measured using the RBB electrode intersects the isoelectric line before the main QRS waveform or morphology. The isoelectric line represents the resting membrane potential and has no positive or negative charges generating deflections. It should be understood that any other EGM signal parameters may be used. In any case, the determined reference points may be used to determine the difference between the reference points and thus determine various cardiac physiological conditions.

[0094] For example, EGM signal parameters and the determined time difference obtained between the parameters of the left ventricle and the right ventricle may be monitored to determine LBB block, RBB block, and normal AV conduction. If the determined time difference from the parameters of the LV to the parameters of the RV is negative, this may indicate LBB block. If the determined time difference from the parameters of the LV to the parameters of the RV is positive and higher than the RBB threshold, this may indicate RBB block. If the determined time difference from the parameters of the LV to the parameters of the RV is positive and lower than the normal conduction threshold, this may indicate normal AV conduction (e.g., no LBB or RBB block).

[0095] The IMD can utilize the determined cardiac physiological condition to, for example, select and deliver a pacing configuration (e.g., cardiac conduction system pacing, myocardial pacing, or other pacing modes). Additionally, the IMD can adjust one or more pacing parameters in the selected pacing configuration to optimize the selected pacing configuration (e.g., pacing pulse voltage, pacing rate, etc.). Additionally, the determined difference between the parameters of the left and right ventricles can be monitored over time to ensure optimized continuous cardiac system pacing for the patient. Exemplary pacing therapy can be delivered using the device described in FIGS. 2 to Figure 4 as described herein.

[0096] Additionally, many cardiac conduction system pacing therapy systems may not include electrodes positioned near the atrium (e.g., right atrium) to acquire and monitor near-field or local atrial electrical activity. For example, a cardiac conduction system pacing therapy system can include electrodes positioned external to the right atrium. In at least one embodiment, a cardiac conduction system pacing therapy system can include only a single-chamber device having an electrode implanted in the RV. As a result, such systems can utilize far-field electrical activity using one or more electrodes positioned external to the right atrium of the patient's heart. Such far-field electrical activity can be processed to determine a P wave indicative of atrial depolarization for use in timing and delivering cardiac conduction system pacing therapy.

[0097] For example, a single-chamber device can include a single lead extending through the right atrium into the RV, as Figures 3A to 3B shown. A dual-chamber device can include one or more leads or one or more leadless devices. For example, a dual-chamber device can include a first lead extending into the right atrium and a second lead extending into the RV, as Figure 2B shown. A triple-chamber device can include multiple leads or multiple leadless devices. For example, a triple-chamber device can include a first lead extending into the RV, a second lead extending into the coronary sinus to an area adjacent to the free wall of the LV, and a third lead extending into the right atrium, as Figure 2A shown.

[0098] In Figure 5Illustrative method 100 for determining a cardiac physiological condition based on a determined difference is depicted, where the determined difference is based on monitored electrical activity (and method 100 may be utilized by the apparatus of FIGS. 2 - 3). Method 100 may include an ongoing delivery of cardiac system pacing therapy (not shown) as a preset for a patient. During the delivery of the therapy, electrical activity of the heart may be monitored using one or more of the electrodes as part of a pacing protocol. Specifically, one or more of intrinsic atrial depolarization or activation, paced atrial depolarization or activation, intrinsic ventricular depolarization or activation, and paced ventricular depolarization or activation may be sensed in the monitored electrical activity for detecting various cardiac physiological conditions. Periodically, in one embodiment, the cardiac system pacing therapy delivered to the ventricles may be paused. In other words, ventricular pacing therapy may be temporarily aborted or inhibited such that electrical activity of the heart may be monitored using one or more of the electrodes, and the monitored electrical activity may be used to detect various cardiac physiological conditions.

[0099] In at least one embodiment, the ongoing delivery of cardiac system pacing therapy may include a set atrioventricular delay. During the paused period, the atrioventricular delay may be set or configured to a time value that is long enough to observe intrinsic conduction of the ventricles for intrinsic depolarization or activation while still delivering pacing therapy if needed. In other words, the atrioventricular delay may be extended or lengthened to allow for intrinsic ventricular activation, but ventricular pacing is still delivered if no intrinsic ventricular activation occurs (e.g., due to AV block, etc.). Reference is made herein Figures 5 to 15 to the determination of various cardiac physiological conditions.

[0100] Method 100 may include: pausing any ongoing pacing or setting an atrioventricular delay long enough to allow for intrinsic conduction, as described herein, and method 100 may include: monitoring electrical activity 102 in one or more implanted electrodes.

[0101] Monitoring electrical activity in the heart may include: monitoring near - field electrical signals using the systems and devices as described above. For example, as described herein, monitoring of electrical activity may be accomplished using sensing module 86. The electrical activity may include near - field electrogram (EGM) signals sensed from at least one implanted electrode. In one or more embodiments, electrical activity may be monitored in the RV and LV of the heart. In an alternative embodiment, electrical activity may be monitored in, on, or around the LBB, RBB, or the left or right ventricular septum, etc. Sensing module 86 or other sensing devices may monitor electrical activity 102 (e.g., EGM signals) during an intrinsic heartbeat.

[0102] In one embodiment, monitoring electrical activity 102 may include: using as described herein with respect to Figures 1 to 4One or more of the implanted electrodes discussed, such as the annular electrode to the can electrode unipolar EGM, the tip electrode to the can electrode unipolar EGM, the RV coil electrode to the can electrode unipolar EGM, and the atrial annular electrode to the can electrode unipolar EGM. The tip electrode can be an electrode located at the tip of any of the leads as described above. The coil electrode can be an electrode formed in or on a coil and positioned along the lead body near the tip of the lead. The annular 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 can electrode can be an electrode located in or around the housing of the IMD. Location identifiers such as RBB are examples of possible electrode locations. For example, the "atrial" location can be one of the atria in either atrium. In an alternative embodiment, bipolar EGM signals can be monitored.

[0103] In one embodiment, and as described above, the RBB unipolar electrode (e.g., the RBB ring for saving a unipolar implant electrogram using electrode 48) can be used to monitor the electrical activity along the RBB of the right ventricle. The RBB unipolar electrode can be used to generate the EGM signal 102B, as Figures 13 to 15 illustrated and labeled in, illustrates Figure 5 at least a portion of the monitored electrical activity of the method 100 of. The LBB unipolar electrode (e.g., the LBB tip for saving a unipolar implant electrogram using electrode 50) can be used to monitor the electrical activity along the LBB of the left ventricle. The LBB unipolar electrode can be used to generate the EGM signal 102C, as Figures 13 to 15 illustrated and labeled in, illustrates Figure 5 at least a portion of the monitored electrical activity of the method 100 of. Additionally, Figures 13 to 15 illustrates the EGM signal 102A, which can be generated using a right atrial ring to house a unipolar implant electrogram (similar to the right atrial electrode 75 discussed herein). Further still, the device or system can also include an LV implantable electrode implanted in the left ventricle but not in the cardiac conduction system, such as described herein with respect to lead 20. The LV electrode 94 can additionally or alternatively be used to monitor Figure 5 the electrical activity of the method 100 of.

[0104] In one embodiment, each of the EGM signals 102B and 102C can be any EGM signal obtained from the RBB and LBB electrodes as discussed herein. In another embodiment, each of the EGM signals 102B and 102C can be a single EGM signal that has passed through a low-pass filter, or can be, for example, an average EGM signal obtained from more than one electrode or over more than one heartbeat. The isopotential lines of the RBB electrode EGM 102B are represented by line 420, and the isopotential lines of the LBB electrode EGM 102C are represented by line 440.

[0105] The monitored electrical activity can be based on, for example, the patient's intrinsic ventricular cardiac electrical activity during the ventricular pacing pause as described herein following RA sensing or pacing of the cardiac electrical activity.

[0106] Method 100 can further include: detecting electrical activity 104 indicative of LV and RV depolarization based on the monitored electrical activity 102 (and as Figures 5 to 15 illustrated and further described herein). For example, the detected electrical activity indicative of LV depolarization can be based on the monitored electrical activity from the LBB electrode. The detected electrical activity indicative of RV depolarization can be based on the monitored electrical activity from the RBB electrode. The detected electrical activity indicative of LV depolarization and the detected electrical activity indicative of RV depolarization can be determined based on the monitored electrical activity from an initial monitored heartbeat, based on a second monitored heartbeat, based on subsequent monitored heartbeats, based on an average heartbeat, etc.

[0107] In one embodiment, the EGM signal 102B is used to illustrate RV depolarization, and the EGM signal 102C is used to illustrate LV depolarization. For example, RV depolarization is detected based on the RBB reference point 520 in the monitored EGM signal 102B, and LV depolarization is detected based on the LBB reference point 540 in the monitored EGM signal 102C. The reference point 520 illustrates the monitored QRS deflection indicative of RV depolarization via the RBB electrode. The reference point 540 illustrates the monitored QRS deflection indicative of LV depolarization via the LBB electrode.

[0108] In another embodiment, LV depolarization is detected based on an LV reference point (not shown) in the monitored EGM signal of the septal LV electrode (as discussed herein with respect to Figure 2A ). Hereinafter, the LBB reference point is understood to cover both the EGM signal using the LBB electrode and the EGM signal using the LV electrode.

[0109] The fiducial points discussed herein can be any measurable points within the near-field electrical activity signal or its derivatives (e.g., differential signals) that correspond to or are related to the actual corresponding chamber depolarization. To determine the fiducial points, the devices and systems as described herein can use any calculation or method (such as by using the sensing module 86 as described herein, the processor 80 as described herein, etc.) to identify the fiducial points. Some examples of fiducial points can include one or more of the following: the start 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, the points where the monitored electrical activity intersects the isopotential lines 420, 440 (which can be located, for example, at 0 volts), any other monitored electrical activity signal waveforms, etc. In one embodiment, the fiducial points 520, 540 are where the monitored electrical activity intersects the isopotential lines 420, 440, as discussed herein.

[0110] Method 100 may further include: determining a difference 106 based on the detected electrical activity (illustrated as "X" in Figures 13 to 15 ). In one embodiment, determining the difference X may include: measuring any detectable time difference from the LBB fiducial point 540 to the RBB fiducial point 520 (such as the optional method 106A and block 118 illustrated in Figure 6 ). If the LBB fiducial point 540 occurs before the RBB fiducial point 520, the difference X may be positive, and if the RBB fiducial point 520 occurs before the LBB fiducial point 540, the difference X may be negative. In an alternative embodiment, for example, the difference X may include measuring any detectable time difference from the RBB fiducial point 520 to the LBB fiducial point 540, such that if the RBB fiducial point occurs before the LBB fiducial point, X is positive, and if the LBB fiducial point occurs before the RBB fiducial point, X is negative. In another alternative embodiment, the difference X may include measuring any detectable time difference from the LV depolarization to the RV depolarization, and vice versa. For the purposes of this disclosure, the difference X is discussed as any detectable time difference from the LBB fiducial point 540 to the RBB fiducial point 520 for determining LBB block, RBB block, and intrinsic AV conduction (such as the optional method 106A and block 118 illustrated in Figure 6 ). For the purposes of this disclosure, the difference X is also discussed as any detectable time difference from at least one of (Ap) or (As) to the LV depolarization and the time difference from at least one of (Ap) or (As) to the RV depolarization for determining AV block (such as the optional method 108A and block 121 illustrated in Figure 7 ). Thus, the difference X is always based on the detected electrical activity 106.

[0111] In one embodiment, the EGM signal using the RBB electrode 102B may include an RBB reference point 520, which may be identified during an intrinsic heartbeat during a pause in pacing as described herein (or during intrinsic conduction during a long atrioventricular delay). The monitored electrical activity from the intrinsic heartbeat may be monitored during the first heartbeat after pacing is paused (or the atrioventricular delay is lengthened), or it may be monitored during the second or subsequent or average heartbeat after pacing is paused (or the atrioventricular delay is lengthened).

[0112] In an alternative embodiment, an RA electrode 75 that can be positioned adjacent to a portion of the patient's RA may be used to pace the heart. Such an electrode may be as described above with respect to Figure 3A described. The computing device is also configured to use the RA electrode 75 to deliver RA pacing. Thus, in any embodiment, the heart either beats intrinsically or via RA pacing. In such alternative embodiments, the atrioventricular delay may be set long enough to allow intrinsic conduction. The monitored electrical activity from the paced heartbeat may be monitored during the first paced heartbeat, or it may be monitored during the second or subsequent or average paced heartbeat.

[0113] As described herein, the RBB reference point 520 may be identified in various ways. For example, the RBB reference point 520 may be determined based on the monitored electrical activity of an implantable RBB electrode 48 that can be positioned adjacent to a portion of the RBB 8b (as illustrated in block 114 of Figure 6 ). Similarly, the EGM signal using the LBB electrode 102C may include an LBB reference point 540, which may be identified in the same intrinsic heartbeat as the RBB reference point 520. For example, the LBB reference point 540 may be determined based on the monitored electrical activity of an implantable LBB electrode 50 that can be positioned adjacent to a portion of the LBB 8a (as illustrated in block 116 of Figure 6 ). In the described embodiment, the electrode 48 is a ring electrode and the electrode 50 is a tip electrode, and both are coupled to the IMD housing and any housing electrodes located therein (as described herein).

[0114] In another embodiment, one or more implantable electrodes further include an LV electrode that can be positioned adjacent to a portion of the patient's LV, such as described herein with respect to lead 20. Detecting electrical activity indicative of LV depolarization may be based on the monitored electrical activity using an LV electrode 94 that is opposite or in addition to the LBB electrode.

[0115] As discussed herein, the determined time difference X between the EGM signal and the reference point can be used to determine the cardiac physiological condition. Also as discussed herein, the EGM signal and the determined difference X can be periodically monitored and measured to ensure the accuracy of the determined difference X, and the relative consistency of the determined difference X over time or at one or more pacing settings can also be averaged to calculate the determined difference X. Signal noise can cause the waveform to intersect the isopotential line more than once or more frequently, making it difficult to detect the reference point based on the isopotential line. The noise can be filtered such that, for example, crossing the isopotential line can mean exceeding a hysteresis threshold added to the isopotential line.

[0116] The relative consistency of the determined difference X (as defined anywhere in this specification) can be determined over time. For example, the relative consistency of the determined difference X can be defined as having the difference X at one intrinsic heartbeat within about 9% of the difference X at a previous intrinsic heartbeat (e.g., the immediately previous heartbeat or another previous heartbeat). In other embodiments, the defined consistency can be maintained within about 5%, or about 10%, or about 15%, or about 20%, or about 25%, or about 30%, or about 35%, or about 40%, or about 50%, or about 60%, or about 70%, or about 80%, or about 90% of the difference X at the previous intrinsic heartbeat. In another embodiment, the consistency can be defined according to a ratio relative to a percentage, or can be defined according to a set difference X time value or threshold. Further, for example, the consistency can be any consistency within a selected range.

[0117] After determining the difference X based on any detectable time difference from at least one of (Ap) or (As) to LV depolarization and the time difference from at least one of (Ap) or (As) to RV depolarization, method 100 can further include: determining the cardiac physiological condition 108 based on the determined difference X. As Figure 7 Illustrated, method 108A can include: determining AV block 120 based on the determined difference. Such determination can analyze the time (e.g., milliseconds) between at least one of (Ap) and (As) and the depolarization of the LV and whether the time between at least one of (Ap) and (As) and the depolarization of the RV is higher than the AV conduction threshold 121. If the determined time is higher than the AV conduction threshold, this indicates AV block 123. If the determined time is not higher than the AV conduction threshold, this indicates no AV block 122.

[0118] An AV conduction threshold can be pre-set for a patient, such as by a physician or other healthcare professional, based on the patient's physiological condition and needs. The AV conduction threshold can be based on a statistical analysis of a specific group having shared characteristics. The AV conduction threshold can be determined according to a template heartbeat. In another embodiment, AV block can be determined by monitoring, for example, the PR interval or QRS morphology of one or more electrograms from an implanted device to determine whether the patient has AV block.

[0119] The AV conduction threshold can be between approximately 200 ms and approximately 450 ms. In at least one embodiment, the AV conduction threshold is 300 ms. In other embodiments, the AV conduction threshold can be greater than or equal to 200 ms, greater than or equal to 250 ms, greater than or equal to 275 ms, greater than or equal to 300 ms, greater than or equal to 350 ms, greater than or equal to 400 ms, greater than or equal to 450 ms, etc., and / or less than or equal to 450 ms, less than or equal to 400 ms, less than or equal to 350 ms, less than or equal to 300 ms, less than or equal to 250 ms, less than or equal to 200 ms, etc.

[0120] In any embodiment, if AV block is not determined, the device, system, and method can continue to determine other cardiac physiological conditions. If AV block is determined, the device, system, and method may not continue to determine other cardiac physiological conditions as discussed herein. Additionally, if LV depolarization and RV depolarization occur after atrial activity at or greater than the AV conduction threshold, the patient may have AV conduction block, and the device, system, and method may not continue to determine other cardiac physiological conditions as discussed herein.

[0121] Further, if there are ectopics in the heartbeat monitored using the monitored electrical activity, there may be an inconsistent PP interval or an inconsistent RR interval between the monitored heartbeat and the previous average heart rate. If there are ectopics, the device, system, and method may not continue to determine other cardiac physiological conditions as discussed herein. If there are no ectopics, the device, system, and method can continue to determine other cardiac physiological conditions as discussed herein.

[0122] As Figure 8 illustrated, method 108A can include: determining LBB block 126 based on the determined difference. Such determination can analyze whether the determined time difference X (e.g., in milliseconds) from the depolarization of the LV to the depolarization of the RV is negative 127. This is in Figure 13is illustrated, where the RBB reference point 520 occurs before the LBB reference point 540 and thus results in a negative time difference. If the determined time difference X is negative, this indicates an LBB block 129. If the determined time difference X is not negative, this indicates no LBB block 128. Additionally, in some cases, the determined difference may be negative (e.g., due to signal noise), but the patient has not experienced an LBB block. In an alternative embodiment, if the determined difference X is negative and below the LBB threshold (not shown), this indicates an LBB block.

[0123] The LBB threshold (not shown) can be preset (such as by a physician or other healthcare professional) for a patient and based on the patient's physiological condition and needs. The LBB threshold can be based on a statistical analysis of a specific group having shared characteristics. The LBB threshold can be determined according to a template heartbeat. The LBB threshold can be between about 0 ms and about -40 ms. In at least one embodiment, the LBB threshold is -10 ms. In other embodiments, the LBB threshold can be greater than or equal to -40 ms, greater than or equal to -30 ms, greater than or equal to -20 ms, greater than or equal to -10 ms, greater than or equal to -5 ms, greater than or equal to 0 ms, etc., and / or less than or equal to 0 ms, less than or equal to -5 ms, less than or equal to -10 ms, less than or equal to -20 ms, less than or equal to -30 ms, less than or equal to -40 ms, etc.

[0124] As Figure 9 is illustrated, method 108A can include: determining an RBB block 132 based on the determined difference. Such determination can analyze whether the determined time difference X (e.g., in milliseconds) from the depolarization of the LV to the depolarization of the RV is positive and above the RBB threshold 133. If the determined time difference X is positive and above the RBB threshold, this indicates an RBB block 135. If the determined time difference X is not positive or not above the RBB threshold, this indicates no RBB block 134. This is also illustrated in Figure 14 where the RBB reference point 520 occurs after the LBB reference point 540 (thus a positive time difference), and the value of the determined difference X is above the RBB threshold.

[0125] The RBB threshold can be the same as or different from the AV conduction threshold. The RBB threshold can be preset for a patient and based on the patient's physiological condition and needs (such as by a physician or other healthcare professional). The RBB threshold can be based on a statistical analysis of a specific group having shared characteristics. The RBB threshold can be determined according to a template heartbeat. The RBB threshold can be between approximately 25 milliseconds (ms) and approximately 40 ms. In at least one embodiment, the RBB threshold is 30 ms. In other embodiments, the RBB threshold can be greater than or equal to 30 ms, greater than or equal to 32 ms, greater than or equal to 34 ms, greater than or equal to 36 ms, greater than or equal to 38 ms, greater than or equal to 40 ms, etc., and / or less than or equal to 40 ms, less than or equal to 38 ms, less than or equal to 36 ms, less than or equal to 34 ms, less than or equal to 32 ms, less than or equal to 30 ms, etc.

[0126] As Figure 10 illustrated, method 108D can include: determining normal intrinsic AV conduction 138 based on the determined difference. Such determination can analyze whether the determined time difference X (e.g., in milliseconds) from the depolarization of the LV to the depolarization of the RV is positive (e.g., the left ventricle is activated before the right ventricle) and below the normal conduction threshold 139. If the determined time difference X is positive and below the normal conduction threshold, this is acceptable intrinsic pacing 141. If the determined time difference X is not positive or not below the normal conduction threshold, this indicates unacceptable intrinsic pacing 140. This is also illustrated in Figure 15 where the RBB reference point 520 occurs after the LBB reference point 540, and the value of the determined difference X is below the normal conduction threshold. Acceptable intrinsic pacing is defined as an intrinsic, non-paced heartbeat having normal AV conduction through the heart. Thus, no cardiac conduction system pacing is required, and the cardiac conduction system of the heart functions in a normal and healthy manner.

[0127] The normal conduction threshold may be the same as or different from the AV conduction threshold and the RBB threshold. The normal conduction threshold may be preset for a patient and based on the patient's physiological condition and needs (such as by a physician or other healthcare professional). The normal conduction threshold may be based on a statistical analysis of a specific group having shared characteristics. The normal conduction threshold may be determined according to a template heartbeat. The normal conduction threshold may be between about 10 ms and about 40 ms. In at least one embodiment, the normal conduction threshold is 10 ms. In other embodiments, the normal conduction threshold may be greater than or equal to 15 ms, greater than or equal to 20 ms, greater than or equal to 25 ms, greater than or equal to 27 ms, greater than or equal to 30 s, greater than or equal to 35 ms, greater than or equal to 40 ms, etc., and / or less than or equal to 40 ms, less than or equal to 35 ms, less than or equal to 30 ms, less than or equal to 25 ms, less than or equal to 20 ms, less than or equal to 15 ms, less than or equal to 10 ms, etc.

[0128] In an alternative embodiment, acceptable intrinsic pacing may include a slightly negative determined difference X (e.g., due to signal noise). In such cases, the LBB threshold (not shown) is also used because in some cases, a slightly negative X may indicate acceptable intrinsic pacing and may not indicate LBB block. For example, the LBB threshold may be more negative than the normal conduction threshold. In such alternative embodiments, the normal conduction threshold may be between about -10 ms and about 40 ms. In at least one embodiment, the normal conduction threshold is 0 ms. In other embodiments, the normal conduction threshold may be greater than or equal to -10 ms, greater than or equal to 0 ms, greater than or equal to 10 ms, greater than or equal to 20 ms, greater than or equal to 30 s, greater than or equal to 35 ms, greater than or equal to 40 ms, etc., and / or less than or equal to 40 ms, less than or equal to 35 ms, less than or equal to 30 ms, less than or equal to 25 ms, less than or equal to 20 ms, less than or equal to 10 ms, less than or equal to 0 ms, less than or equal to -10 ms, etc.

[0129] Additionally, if there is unblocked intrinsic AV conduction, the RBB reference point 520 and the LBB reference point 540 are approximately equal in time. For example, the reference points can be spaced apart from each other by about 0 ms to about 15 ms. In at least one embodiment, the difference between them is 0 ms. In other embodiments, the difference between them can be greater than or equal to 1 ms, greater than or equal to 2 ms, greater than or equal to 3 ms, greater than or equal to 4 ms, greater than or equal to 5 ms, greater than or equal to 6 ms, greater than or equal to 7 ms, greater than or equal to 10 ms, greater than or equal to 15 ms, etc., and / or less than or equal to 15 ms, less than or equal to 10 ms, less than or equal to 7 ms, less than or equal to 6 ms, less than or equal to 5 ms, less than or equal to 4 ms, less than or equal to 3 ms, less than or equal to 2 ms, less than or equal to 1 ms, less than or equal to 0 ms, etc.

[0130] Such reference points (when there is unblocked intrinsic conduction) should be below the AV conduction threshold. If the AV delay is short and there is a slight difference in the reference points (as described above), then continued intrinsic activation may be allowed. If the AV delay is not short and there is a difference in the reference points, then continued intrinsic activation may not be allowed and a pacing configuration may be selected.

[0131] A short AV delay can be between about 30 ms and about 70 ms. In at least one embodiment, the short AV delay is 50 ms. In other embodiments, the short AV delay can be 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, greater than or equal to 70 ms, etc., and / or 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, less than or equal to 30 ms, etc.

[0132] As described above, the time from (As) to the reference point can be between about 100 ms and about 280 ms. In at least one embodiment, the time from (As) to the reference point is 200 ms. In other embodiments, the time from (As) to the reference point can be greater than or equal to 150 ms, greater than or equal to 175 ms, greater than or equal to 200 ms, greater than or equal to 225 ms, greater than or equal to 250 ms, etc., and / or less than or equal to 250 ms, less than or equal to 225 ms, less than or equal to 200 ms, less than or equal to 175 ms, less than or equal to 150 ms, etc.

[0133] As described above, the time from (Ap) to the fiducial point can be between about 120 ms and about 300 ms. In at least one embodiment, the time from (Ap) to the fiducial point is 250 ms. In other embodiments, the time from (Ap) to the fiducial point can be greater than or equal to 120 ms, greater than or equal to 200 ms, greater than or equal to 250 ms, greater than or equal to 275 ms, greater than or equal to 300 ms, etc., and / or less than or equal to 300 ms, less than or equal to 275 ms, less than or equal to 250 ms, less than or equal to 225 ms, less than or equal to 120 ms, etc.

[0134] Figure 5 Method 100 may also optionally include selecting a pacing configuration (e.g., cardiac conduction system pacing, myocardial pacing, dual pacing) 110 based on the determined cardiac physiological condition, such as the options illustrated using the optional dashed box. The selected pacing configuration may be selected by a physician or other healthcare professional or may be selected by the device or system. If the selected pacing configuration includes pacing with either or both of the RBB ring electrode 48 and the LBB tip electrode 50, the pacing settings (e.g., voltage, pacing rate, etc.) may be optimized to conserve energy and provide the best possible treatment to the patient. If only one of the above electrodes is used for pacing, more energy savings are possible.

[0135] Various embodiments describing the delivery of cardiac conduction system pacing are discussed herein (e.g., using an IMD). Additionally, method 100 may be performed more than once such that a healthcare provider or user may periodically recheck the determined difference X, change the pacing configuration, pacing configuration settings, etc., based on the determined difference X. Disease progression may make the LBB or RBB block more persistent, and continuous monitoring may ensure optimal treatment of the patient over time.

[0136] Method 100 may also optionally include: delivering pacing 112 based on the selected pacing configuration, and such delivery is also illustrated using the optional dashed box. Such pacing may be accomplished using the devices described with respect to FIGS. 2 to Figure 4 as described.

[0137] Figure 11 is a block diagram of another exemplary method 200 for determining the difference X between the QRS deflections of the left and right ventricles using a device that can be of FIGS. 2 to Figure 4 and using one or more processes the same as or similar to the methods illustrated with Figures 5 to 10 . Figure 11 Method 200 can be applied to or integrated with the capture management features described herein and can also be used to long - term track the trend of the determined difference X as a monitoring feature over time.

[0138] Method 200 includes: setting a timer 202 to know when to pause any ongoing pacing of a patient. Method 200 also includes: checking the IMD device status and setting the EGM polarities 204 of one or more implanted leads and one or more implanted electrodes of the device. Method 200 also includes: skipping the pacing of one heartbeat 206. This ensures that a fully intrinsic heartbeat is monitored as opposed to a paced heartbeat. In an alternative embodiment, the method may include: monitoring the fully intrinsic heartbeat to ensure, for example, that it is not ectopic, or that it is normal. Such normal intrinsic heartbeats may be determined based on statistical analysis of a particular population, or may be determined according to a template normal heartbeat, or may be determined by monitoring QRS morphology (such as QRS width, R wave amplitude, RR interval, PR interval, etc.) or any combination thereof. In a further alternative embodiment, the heartbeat may not be skipped and 206 may not be performed.

[0139] Method 200 also includes: determining the QRS deflections 208 of both the left ventricle and the right ventricle. This may be similar to determining the LBB reference point and the RBB reference point as discussed herein. Method 200 may also include: calculating the difference X (e.g., Δ) between the QRS deflections. This may be similar to determining the difference X as discussed herein. Method 200 may also include: at 212, analyzing whether the difference X is greater than or equal to zero. If the difference X is greater than or equal to zero, any cardiac system pacing (CSP) may be paused and / or a recording may be issued 214. If the difference X is not greater than or equal to zero, CSP may continue 216. Method 200 may also include: resetting the timer for the next check 218, and method 200 may be restarted again at the end of the timer.

[0140] Figure 12 is a simplified illustrative diagram of a portion of the heart and leads that may be utilized by the device of FIGS. 2 through Figure 4 The bundle of His 13, RBB 8b, and LBB 8a are all shaded or filled. The tricuspid valve 6000 is located at the entrance of the RV, while the mitral valve 4000 is located at the entrance of the LV. The cardiac conduction system pacing therapy lead 23 is implanted as described herein, having electrodes 48 and 50 as described herein.

[0141] Various embodiments have been described. These and other embodiments are within the scope of the appended claims. For example, a single-chamber, dual-chamber, or triple-chamber pacemaker (e.g., CRT-P) or ICD (e.g., CRT-D) device may be used to implement the illustrative methods described herein.

[0142] Exemplary embodiments

[0143] While the present disclosure is not limited thereto, an understanding of various aspects of the present disclosure will be obtained by discussing the specific illustrative embodiments provided below. Various modifications to the illustrative embodiments and additional embodiments of the present disclosure will become apparent herein.

[0144] Example Ex1: An implantable medical device, the implantable medical device comprising:

[0145] A computing device, the computing device including processing circuitry and operably coupled to one or more implantable electrodes, the one or more implantable electrodes including an LBB electrode that can be positioned adjacent to a portion of the patient's left bundle branch (LBB) and an RBB electrode that can be positioned adjacent to a portion of the patient's right bundle branch (RBB), wherein the computing device is configured to:

[0146] Use the LBB electrode and the RBB electrode to monitor electrical activity;

[0147] Detect electrical activity based on the monitored electrical activity indicating intrinsic left ventricular (LV) depolarization and indicating intrinsic right ventricular (RV) depolarization;

[0148] Determine a time difference based on the detected electrical activity indicating intrinsic LV depolarization and the detected electrical activity indicating intrinsic RV depolarization; and

[0149] Determine whether a cardiac physiological condition exists based on the determined difference.

[0150] Example Ex2: A method, the method comprising:

[0151] Use one or more implantable electrodes to monitor electrical activity, the one or more implantable electrodes including an LBB electrode positioned adjacent to a portion of the patient's left bundle branch (LBB) and an RBB electrode positioned adjacent to a portion of the patient's right bundle branch (RBB);

[0152] Detect electrical activity based on the monitored electrical activity indicating intrinsic left ventricular (LV) depolarization and indicating intrinsic right ventricular (RV) depolarization;

[0153] Determine a difference based on the detected electrical activity indicating intrinsic LV depolarization and the detected electrical activity indicating intrinsic RV depolarization; and

[0154] Determine whether a cardiac physiological condition exists based on the determined difference.

[0155] Example Ex3: The implantable medical device according to Example Ex1 or the method according to Example Ex2, wherein detecting the electrical activity indicative of intrinsic LV depolarization is based on the electrical activity monitored using the LBB electrode, and wherein detecting the electrical activity indicative of intrinsic RV depolarization is based on the electrical activity monitored using the RBB electrode.

[0156] Example Ex4: The implantable medical device or method according to any one of Examples Ex1 to Ex3, wherein the one or more implantable electrodes further include an LV electrode that can be positioned adjacent to a portion of the patient's LV, and wherein detecting the electrical activity indicative of intrinsic LV depolarization is based on the electrical activity monitored using the LV electrode.

[0157] Example Ex5: The implantable medical device or method according to any one of Examples Ex1 to Ex4, wherein the one or more implantable electrodes further include an RA electrode that can be positioned adjacent to a portion of the patient's right atrium (RA), and wherein the computing device is further configured to perform the following or the method further includes:

[0158] Using the RA electrode to detect intrinsic RA cardiac electrical activity or deliver RA pacing.

[0159] Example Ex6: The implantable medical device or method according to any one of Examples Ex1 to Ex5, wherein the monitored electrical activity is based on at least one of the patient's intrinsic RA cardiac electrical activity and RA-paced cardiac electrical activity, and wherein determining the detected electrical activity indicative of LV depolarization and indicative of RV depolarization is based on at least one of an initially monitored heartbeat or a second or subsequent monitored heartbeat.

[0160] Example Ex7: The implantable medical device or method according to any one of Examples Ex1 to Ex6, wherein the computing device is further configured to perform the following or the method further includes:

[0161] Select a pacing configuration based on the determined cardiac physiological condition; and

[0162] Deliver pacing using one or more implanted electrodes based on the selected pacing configuration.

[0163] Example Ex8: The implantable medical device or method according to any one of Examples Ex1 to Ex7, wherein the determined difference based on the detected electrical activity indicative of LV depolarization and the detected electrical activity indicative of RV depolarization is the time period extending from a reference point of the electrical activity monitored using the LBB electrode to a reference point of the electrical activity monitored using the RBB electrode.

[0164] Example Ex9: The implantable medical device or method according to Example Ex8, wherein the reference point of the electrical activity monitored using the LBB electrode is the earliest monitored QRS deflection, and wherein the reference point of the electrical activity monitored using the RBB electrode is the earliest monitored QRS deflection.

[0165] Example Ex10: The implantable medical device or method according to Example Ex9, wherein the respective earliest monitored QRS deflections are determined as the points at which the respective monitored electrical activities intersect the respective isopotential lines of the electrical activity monitored using the LBB electrode and the respective isopotential lines of the electrical activity monitored using the RBB electrode.

[0166] Example Ex11: The implantable medical device or method according to any one of Examples Ex1 to Ex10, wherein, in order to determine whether a cardiac physiological condition exists based on the determined difference, the computing device is further configured to perform the following or the method further comprises:

[0167] Determine whether atrioventricular (AV) block exists based on the time from at least one of an atrial pacing event and an atrial sensing event to LV depolarization and the time from the at least one of the atrial pacing event and the atrial sensing event to RV depolarization.

[0168] Example Ex12: The implantable medical device or method according to Example Ex11, wherein determining whether AV block exists based on the time from at least one of the atrial pacing event and the atrial sensing event to LV depolarization and the time from at least one of the atrial pacing event and the atrial sensing event to RV depolarization comprises: determining that the time from at least one of the atrial pacing event and the atrial sensing event to LV depolarization and the time from at least one of the atrial pacing event and the atrial sensing event to RV depolarization are higher than an AV conduction threshold.

[0169] Example Ex13: The implantable medical device or method according to Example Ex12, wherein the AV conduction threshold is determined according to one or more of the electrical activity of a template heartbeat and a preset value.

[0170] Example Ex14: The implantable medical device or method according to any one of Examples Ex1 to Ex13, wherein, in order to determine whether a cardiac physiological condition exists based on the determined difference, the computing device is further configured to perform the following or the method further comprises:

[0171] Determine whether LBB block exists based on the determined difference.

[0172] Example Ex15: The implantable medical device or method according to Example Ex14, wherein determining whether there is an LBB block based on the determined difference includes: determining that the determined difference from LV depolarization to RV depolarization is negative.

[0173] Example Ex16: The implantable medical device or method according to any one of Examples Ex1 to Ex15, wherein in order to determine whether there is a cardiac physiological condition based on the determined difference, the computing device is further configured to perform the following or the method further includes:

[0174] Determining whether there is an RBB block based on the determined difference.

[0175] Example Ex17: The implantable medical device or method according to Example Ex16, wherein determining whether there is an RBB block based on the determined difference includes: determining that the determined difference from LV depolarization to RV depolarization is positive and higher than the RBB threshold.

[0176] Example Ex18: The implantable medical device or method according to Example Ex17, wherein the RBB threshold is determined according to one or more of the electrical activity of the template heartbeat and a preset value.

[0177] Example Ex19: The implantable medical device or method according to any one of Examples Ex1 to Ex18, wherein in order to determine whether there is a cardiac physiological condition based on the determined difference, the computing device is further configured to perform the following or the method further includes:

[0178] Determining whether there is unblocked intact intrinsic AV conduction based on the determined difference.

[0179] Example Ex20: The implantable medical device or method according to Example Ex19, wherein determining whether there is unblocked intact intrinsic AV conduction based on the determined difference includes: determining that the determined difference from LV depolarization to RV depolarization is positive and lower than the normal conduction threshold.

[0180] Example Ex21: The implantable medical device or method according to Example Ex20, wherein the normal conduction threshold is determined according to one or more of the electrical activity of the template heartbeat and a preset value.

[0181] Example Ex22: A system, the system includes:

[0182] A conduction system pacing lead, the conduction system pacing lead includes:

[0183] One or more implantable electrodes, the one or more implantable electrodes including an LBB electrode capable of being positioned adjacent to a portion of a patient's left bundle branch (LBB) and an RBB electrode capable of being positioned adjacent to a portion of the patient's right bundle branch (RBB); and

[0184] An implantable medical device, the implantable medical device including:

[0185] A computing device, the computing device including processing circuitry and being operably coupled to the one or more implantable electrodes, wherein the computing device is configured to:

[0186] Use the one or more implantable electrodes to monitor electrical activity;

[0187] Detect electrical activity based on the monitored electrical activity indicative of intrinsic left ventricular (LV) depolarization and indicative of intrinsic right ventricular (RV) depolarization;

[0188] Determine a difference based on the detected electrical activity indicative of intrinsic LV depolarization and the detected electrical activity indicative of intrinsic RV depolarization; and determine whether a cardiac physiological condition exists based on the determined difference.

[0189] Example Ex23: The system according to Example Ex22, wherein the computing device is further configured to:

[0190] Select a pacing configuration based on the determined cardiac physiological condition; and

[0191] Deliver pacing based on the selected pacing configuration using one or more implanted electrodes.

[0192] Example Ex24: The system according to any one of Examples Ex22 to Ex23, the system further including:

[0193] A ventricular lead, the ventricular lead including one or more implantable electrodes, the one or more implantable electrodes including an LV electrode capable of being positioned adjacent to a portion of the patient's LV,

[0194] Wherein the computing device is further configured to use the LV electrode to detect electrical activity indicative of intrinsic LV depolarization.

[0195] Example Ex25: The system according to any one of Examples Ex22 to Ex24, the system further including:

[0196] An atrial lead, the atrial lead including one or more implantable electrodes, the one or more implantable electrodes including an RA electrode capable of being positioned adjacent to a portion of the patient's right atrium (RA),

[0197] Wherein the computing device is further configured to detect intrinsic RA cardiac electrical activity or deliver RA pacing using the RA electrode.

[0198] The present disclosure has been provided with reference to exemplary embodiments and examples and is not meant to be construed in a limiting sense. As previously mentioned, those skilled in the art will recognize that various other exemplary applications can utilize the beneficial features of the devices and methods described herein using the techniques described herein. Various modifications of the exemplary embodiments and examples will become apparent upon reference to this specification.

[0199] 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 on a computer-readable medium as one or more instructions or code and executed by a hardware-based processing unit. The computer-readable medium may include a 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 that can be accessed by a computer).

[0200] The instructions may be executed by one or more processors such as one or more digital signal processors (DSPs), general microprocessors, application specific integrated circuits (ASICs), field programmable gate arrays (FPGAs), or other equivalent integrated or discrete logic circuitry. Thus, as used herein, the term "processor" may refer to any one of the foregoing structures or any other physical structure suitable for implementing the described techniques. Additionally, the techniques may be fully implemented in one or more circuits or logic elements.

[0201] All references and publications cited herein are expressly incorporated herein by reference in their entirety for all purposes, unless any aspect is in direct contradiction with the present disclosure.

[0202] Unless otherwise indicated, 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 commonly used herein and are not intended to limit the scope of the present disclosure.

[0203] Unless otherwise specified, all numerical values representing feature sizes, amounts, and physical properties used in the specification and claims can be understood to be modified by the term "exactly" or "about". Accordingly, unless indicated to the contrary, the numerical parameters set forth in the foregoing specification and attached claims are approximations that may vary depending on the desired properties sought to be obtained by those skilled in the art using the teachings disclosed herein or, for example, within the typical range of experimental error.

[0204] Narrating a numerical range through endpoints includes all numerical values within the said range (for example, 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, and 5) and any range within the said range. In this article, the term "at most" or "not greater than" a numerical value (for example, at most 50) includes this numerical value (for example, 50), and the term "not less than" a numerical value (for example, not less than 5) includes this numerical value (for example, 5).

[0205] The term "coupled" or "connected" means that components are directly attached to each other (in direct contact with each other) or indirectly attached (having one or more components between the two components and attaching the two components). Both of these terms can be modified by the interchangeable "operably" and "operatively" to describe that the coupling or connection is configured to allow components to interact to perform at least some functions (for example, a mobile user device can be operably coupled to a cellular network to send data to it or receive data from it).

[0206] References to "one embodiment", "an embodiment", "certain embodiments", or "some embodiments", etc. mean that the specific features, configurations, compositions, or characteristics described in connection with that embodiment are included in at least one embodiment of the present disclosure. Therefore, the appearance of such phrases throughout the text does not necessarily refer to the same embodiment of the present disclosure. In addition, the specific features, configurations, compositions, or characteristics can be combined in any suitable manner in one or more embodiments.

[0207] As used in this specification and the appended claims, the singular forms "a / an" and "the" cover embodiments having multiple referents, unless the context clearly dictates otherwise. As used in this specification and the appended claims, the term "or" is generally used in its inclusive sense, including "and / or", unless otherwise clearly specified in the text.

[0208] As used herein, "having", "including", "containing", 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 in "including", etc.

[0209] The term "and / or" means a combination of one or all of the listed elements or at least two of the listed elements.

[0210] The phrases "at least one of...", "including at least one of...", and "one or more of..." accompanying a list refer to any one item in the list and any combination of two or more items in the list.

Claims

1. An implantable medical device, the implantable medical device comprising: A computing device, the computing device including processing circuitry and operably coupled to one or more implantable electrodes, the one or more implantable electrodes including an LBB electrode capable of being positioned adjacent to a portion of a patient's left bundle branch (LBB) and an RBB electrode capable of being positioned adjacent to a portion of the patient's right bundle branch (RBB), wherein the computing device is configured to: Use the LBB electrode and the RBB electrode to monitor electrical activity; Detect electrical activity based on the monitored electrical activity indicative of intrinsic left ventricular (LV) depolarization and indicative of intrinsic right ventricular (RV) depolarization; Determine a time difference based on the detected electrical activity indicative of intrinsic LV depolarization and the detected electrical activity indicative of intrinsic RV depolarization; And Determine whether a cardiac physiological condition exists based on the determined difference.

2. A method, the method comprising: Use one or more implantable electrodes to monitor electrical activity, the one or more implantable electrodes including an LBB electrode positioned adjacent to a portion of a patient's left bundle branch (LBB) and an RBB electrode positioned adjacent to a portion of the patient's right bundle branch (RBB); Detect electrical activity based on the monitored electrical activity indicative of intrinsic left ventricular (LV) depolarization and indicative of intrinsic right ventricular (RV) depolarization; Determine a difference based on the detected electrical activity indicative of intrinsic LV depolarization and the detected electrical activity indicative of intrinsic RV depolarization; And Determine whether a cardiac physiological condition exists based on the determined difference.

3. The implantable medical device according to claim 1 or the method according to claim 2, wherein detecting the electrical activity indicative of intrinsic LV depolarization is based on the electrical activity monitored using the LBB electrode, and wherein detecting the electrical activity indicative of intrinsic RV depolarization is based on the electrical activity monitored using the RBB electrode.

4. The implantable medical device or method according to any one of claims 1 to 3, wherein the one or more implantable electrodes further comprise LV electrodes that can be positioned adjacent to a portion of the patient's LV, and wherein detecting the electrical activity indicative of intrinsic LV depolarization is based on the electrical activity monitored using the LV electrodes.

5. The implantable medical device or method according to any one of claims 1 to 4, wherein the one or more implantable electrodes further comprise RA electrodes that can be positioned adjacent to a portion of the patient's right atrium (RA), and wherein the computing device is further configured to perform the following or the method further comprises: Use the RA electrode to detect intrinsic RA cardiac electrical activity or deliver RA pacing.

6. The implantable medical device or method according to any one of claims 1 to 5, wherein the monitored electrical activity is based on at least one of the patient's intrinsic RA cardiac electrical activity and RA-paced cardiac electrical activity, and wherein determining the detected electrical activity indicative of LV depolarization and indicative of RV depolarization is based on at least one of an initially monitored heartbeat or a second or subsequent monitored heartbeat.

7. The implantable medical device or method according to any one of claims 1 to 6, wherein the computing device is further configured to perform the following or the method further comprises: Select a pacing configuration based on the determined cardiac physiological condition; And Use one or more implanted electrodes to deliver pacing based on the selected pacing configuration.

8. The implantable medical device or method according to any one of claims 1 to 7, wherein the determined difference based on the detected electrical activity indicative of LV depolarization and the detected electrical activity indicative of RV depolarization is the time period extending from a reference point of the electrical activity monitored using the LBB electrode to a reference point of the electrical activity monitored using the RBB electrode.

9. The implantable medical device or method according to claim 8, wherein the reference point of the electrical activity monitored using the LBB electrode is the earliest detected QRS deflection, and wherein the reference point of the electrical activity monitored using the RBB electrode is the earliest detected QRS deflection.

10. The implantable medical device or method according to claim 9, wherein the respective earliest detected QRS deflections are determined as the points at which the respective monitored electrical activities intersect the respective isopotential lines of the electrical activity monitored using the LBB electrode and the respective isopotential lines of the electrical activity monitored using the RBB electrode.

11. The implantable medical device or method according to any one of claims 1 to 10, wherein in order to determine whether a cardiac physiological condition exists based on the determined difference, the computing device is further configured to perform the following or the method further comprises: Determine whether atrioventricular (AV) block exists based on the time from at least one of an atrial pacing event and an atrial sensing event to LV depolarization and the time from the at least one of the atrial pacing event and the atrial sensing event to RV depolarization.

12. The implantable medical device or method according to claim 11, wherein determining whether AV block exists based on the time from at least one of the atrial pacing event and the atrial sensing event to LV depolarization and the time from at least one of the atrial pacing event and the atrial sensing event to RV depolarization comprises: Determine that the time from the at least one of the atrial pacing event and the atrial sensing event to LV depolarization and the time from the at least one of the atrial pacing event and the atrial sensing event to RV depolarization are above an AV conduction threshold.

13. The implantable medical device or method according to claim 12, wherein the AV conduction threshold is determined based on one or more of the electrical activity of a template heartbeat and a preset value.

14. The implantable medical device or method according to any one of claims 1 to 13, wherein in order to determine whether a cardiac physiological condition exists based on the determined difference, the computing device is further configured to perform the following or the method further comprises: Determine whether LBB block exists based on the determined difference.

15. The implantable medical device or method according to claim 14, wherein determining whether LBB block exists based on the determined difference comprises: Determine that the determined difference from LV depolarization to RV depolarization is negative.

16. The implantable medical device or method according to any one of claims 1 to 15, wherein in order to determine whether a cardiac physiological condition exists based on the determined difference, the computing device is further configured to perform the following or the method further comprises: Determine whether RBB block exists based on the determined difference.

17. The implantable medical device or method according to claim 16, wherein determining whether there is a RBB block based on the determined difference includes: Determine that the determined difference from LV depolarization to RV depolarization is positive and above an RBB threshold.

18. The implantable medical device or method according to claim 17, wherein the RBB threshold is determined according to one or more of the electrical activity of the template heartbeat and a preset value.

19. The implantable medical device or method according to any one of claims 1 to 18, wherein in order to determine whether there is a cardiac physiological condition based on the determined difference, the computing device is further configured to perform the following or the method further includes: Determine whether unblocked intact intrinsic AV conduction exists based on the determined difference.

20. The implantable medical device or method according to claim 19, wherein determining whether there is unblocked intact intrinsic AV conduction based on the determined difference includes: Determine that the determined difference from LV depolarization to RV depolarization is positive and below a normal conduction threshold.

21. The implantable medical device or method according to claim 20, wherein the normal conduction threshold is determined according to one or more of the electrical activity of the template heartbeat and a preset value.

22. A system, the system comprising: A conduction system pacing lead, the conduction system pacing lead including: One or more implantable electrodes, the one or more implantable electrodes including an LBB electrode capable of being positioned adjacent to a portion of a patient's left bundle branch (LBB) and an RBB electrode capable of being positioned adjacent to a portion of the patient's right bundle branch (RBB); and An implantable medical device, the implantable medical device comprising: A computing device, the computing device including processing circuitry and being operatively coupled to the one or more implantable electrodes, wherein the computing device is configured to: Monitor electrical activity using the one or more implantable electrodes; Detect electrical activity based on the monitored electrical activity indicative of intrinsic left ventricle (LV) depolarization and indicative of intrinsic right ventricle (RV) depolarization; Determine a difference based on the detected electrical activity indicative of intrinsic LV depolarization and the detected electrical activity indicative of intrinsic RV depolarization; and Determine whether a cardiac physiological condition exists based on the determined difference.

23. The system according to claim 22, wherein the computing device is further configured to: select a pacing configuration based on the determined cardiac physiological condition; and deliver pacing based on the selected pacing configuration using one or more implanted electrodes.

24. The system according to any one of claims 22 to 23, the system further comprising: A ventricular lead, the ventricular lead including one or more implantable electrodes, the one or more implantable electrodes including an LV electrode that can be positioned adjacent to a portion of the patient's LV, wherein the computing device is further configured to detect electrical activity indicative of intrinsic LV depolarization using the LV electrode.

25. The system according to any one of claims 22 to 24, the system further comprising: An atrial lead, the atrial lead including one or more implantable electrodes, the one or more implantable electrodes including an RA electrode that can be positioned adjacent to a portion of the patient's right atrium (RA), wherein the computing device is further configured to detect intrinsic RA cardiac electrical activity or deliver RA pacing using the RA electrode.

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