Implantable medical system with the ability to switch between cardiac resynchronization therapy modes using mechanical activity

Abstract

An implantable medical system is used to: determine whether electrical activity indicates atrial fibrillation, determine whether mechanical activity indicates atrial fibrillation, and adjust pacing parameters or modes based on whether the electrical and mechanical activity indicate atrial fibrillation. Electrical activity can be detected based on far-field measurements. The system may include a leadless implantable medical device having a first electrode, a second electrode, a motion sensor for sensing mechanical activity of the heart, and a controller coupled to the first electrode, the second electrode, and the motion sensor. The controller is configured to switch between a dual-chamber sensing mode that delivers pacing based on sensing the electrical activity of at least one atrium and at least one ventricle of a patient's heart and a single-chamber sensing mode that delivers pacing based on sensing the electrical activity of only one or two ventricles of a patient's heart; in the dual-chamber sensing mode, pacing is delivered to at least one ventricle of the patient's heart using a first electrode; determining whether the electrical activity of one or two atria sensed by the second electrode indicates atrial fibrillation; in response to determining that the electrical activity of one or two atria indicates atrial fibrillation, determining whether the mechanical activity of the patient's heart sensed by the motion sensor indicates atrial contraction; and in response to determining that the mechanical activity of the patient's heart does not indicate atrial contraction, delivering suppressed pacing using the first electrode in the single-chamber sensing mode.

Description

[0001] This technology generally involves cardiac treatment, especially cardiac resynchronization therapy.

[0002] Cardiac therapy can be provided by implantable medical devices such as pacemakers or implantable cardioverter-defibrillators (ICDs), which deliver therapeutic electrical stimulation to a patient's heart via electrodes through one or more implantable leads. Therapeutic electrical stimulation can be delivered to the heart in the form of pulses or shocks used for pacing, cardioverter-defibrillation, or defibrillation. In some cases, implantable medical devices can sense the heart's inherent depolarization or inherent activation and control the delivery of therapeutic stimulation to the heart based on the sensed inherent activation.

[0003] Cardiac resynchronization therapy (CRT) is a type of treatment delivered by implantable medical devices. CRT can help increase cardiac output by resynchronizing the electromechanical activity of the ventricles. For example, ventricular dyssynchrony can occur in patients with congestive heart failure. CRT may vary depending on various parameters, such as the presence of atrial fibrillation (AF). Summary of the Invention

[0004] The techniques disclosed herein generally relate to cardiac treatment systems and methods that utilize mode switching to manage different sensing and pacing modes, such as during CRT based on the presence of atrial fibrillation (AF). Specifically, mechanical activity can be used to confirm electrical activity indicating the presence of AF. In some embodiments, signals from motion sensors can be used to confirm whether one or both atria are in AF, or whether P-wave detection parameters, such as detection sensitivity parameters or P-wave blanking period, should be adjusted.

[0005] In one aspect, this disclosure provides an implantable medical system comprising: a first electrode for sensing electrical activity of one or two ventricles of a patient's heart or for delivering cardiac treatment to one or two ventricles of the patient's heart; a second electrode for sensing electrical activity of one or two atria of the patient's heart; a motion sensor for sensing mechanical activity of the patient's heart; and a controller operatively coupled to the first electrode, the second electrode, and the motion sensor. The controller is configured to: switch between a dual-chamber sensing mode that delivers pacing based on sensing the electrical activity of at least one atrium and at least one ventricle of the patient's heart and a single-chamber sensing mode that delivers pacing based on sensing the electrical activity of only one or two ventricles of the patient's heart; deliver pacing to at least one ventricle of the patient's heart using the first electrode in the dual-chamber sensing mode; determine whether the electrical activity of one or two atria sensed by the second electrode indicates atrial fibrillation; determine whether the mechanical activity of the patient's heart sensed by the motion sensor indicates atrial contraction in response to determining that the electrical activity of one or two atria indicates atrial fibrillation; and deliver suppressed pacing using the first electrode in the single-chamber sensing mode in response to determining that the mechanical activity of the patient's heart does not indicate atrial contraction.

[0006] In another aspect, this disclosure provides a method comprising: delivering pacing to at least one ventricle of a patient's heart in a dual-chamber sensing mode based on sensing electrical activity of at least one atrium and at least one ventricle of a patient's heart; determining whether electrical activity of one or both atria of the patient's heart indicates atrial fibrillation; determining whether mechanical activity of the patient's heart indicates atrial contraction in response to determining that the electrical activity of one or both atria indicates atrial fibrillation; and delivering suppressed pacing to at least one ventricle of the patient's heart in a single-chamber sensing mode based on sensing electrical activity of only one or two ventricles of the patient's heart in response to determining that the mechanical activity of the patient's heart does not indicate atrial contraction.

[0007] In another aspect, this disclosure provides an implantable medical system comprising: a first medical device having a housing capable of being implanted in at least one ventricle of a patient's heart; the first medical device comprising: at least one electrode for sensing electrical activity of at least one ventricle of the patient's heart or delivering cardiac treatment to at least one ventricle of the patient's heart; and at least one motion sensor for sensing mechanical activity of the patient's heart. The system further comprises a second medical device operatively in communication with the first medical device, and a controller having at least one electrode for sensing electrical activity of one or both atria of the patient's heart. The controller is configured to: switch between a dual-chamber sensing mode that delivers pacing based on sensing the electrical activity of at least one atrium and at least one ventricle of the patient's heart and a single-chamber sensing mode that delivers pacing based on sensing the electrical activity of only one or two ventricles of the patient's heart; deliver pacing to at least one ventricle of the patient's heart in the dual-chamber sensing mode; determine whether the electrical activity of one or two atria sensed by the second medical device indicates atrial fibrillation; determine whether the mechanical activity of the patient's heart sensed by the first medical device indicates atrial contraction in response to determining that the electrical activity of one or two atria indicates atrial fibrillation; and deliver suppressed pacing to at least one ventricle of the patient's heart in the single-chamber sensing mode in response to determining that the mechanical activity of the patient's heart does not indicate atrial contraction.

[0008] Details of one or more aspects of this disclosure are set forth in the accompanying drawings and the following description. Other features, objectives, and advantages of the technology described in this disclosure will be apparent from the specification, drawings, and claims. Attached Figure Description

[0009] Figure 1 This is a conceptual diagram illustrating an example of a cardiac treatment system including a first medical device and a second medical device according to the present disclosure.

[0010] Figure 2 It shows that it can be used with, for example Figure 1 A conceptual diagram of an example of an implantable medical device inserted from the Koch triangle for use with cardiac treatment systems.

[0011] Figure 3 It is shown that, for example, Figure 1 A conceptual diagram of the electrode implantation location relative to the patient's heart map in a standard 17-segment view used in cardiac treatment systems.

[0012] Figure 4 It is shown that, for example, Figure 1A conceptual diagram of an example controller used in cardiac treatment systems.

[0013] Figure 5 It is shown that, for example, Figure 1 A flowchart illustrating an example of a mode-switching method used in conjunction with a cardiac treatment system.

[0014] Figure 6 It is shown that, for example, Figure 1 The implementation of using cardiac treatment systems Figure 5 A flowchart of an example of a specific method of the method.

[0015] Figure 7 It is shown that, for example, Figures 5 to 6 Method or Figure 1 A graph showing various intervals of electrical and mechanical activity signals used in cardiac treatment systems. Detailed Implementation

[0016] This disclosure relates to cardiac treatment, and more particularly to cardiac radiotherapy (CRT). Some types of CRT can utilize mode switching in response to specific conditions of the patient's heart, such as switching between different types of sensing modes and pacing modes. For example, some cardiac treatment systems can be configured to switch from VDD / DDD mode to VVI mode when AF is detected.

[0017] Some cardiac therapy systems are implanted only in certain areas or chambers of the heart. These systems can utilize far-field sensing technology to detect activity in other areas of the heart. During cardiac resuscitation (CRT) in a patient's heart, the P wave (also known as the atrial P wave) can be sensed by the cardiac therapy system and used to trigger pacing after a predetermined atrioventricular (AV) delay, such as in a VDD / DDD sensing and pacing mode.

[0018] Accurately sensing P waves using far-field sensing techniques may be more challenging than using near-field sensing techniques because far-field P waves are relatively smaller in size (such as amplitude or oscillation) and may contain noise sources compared to near-field P waves. Atrial fibrillation may further reduce the size of far-field P waves, which could complicate the challenge of detecting P waves using far-field sensing techniques.

[0019] This disclosure provides cardiac treatment systems and methods that utilize mode switching to manage different sensing and pacing modes during CRT based on the presence of atrial fibrillation (AF). Specifically, mechanical activity can be used to confirm electrical activity indicating the presence of AF. In some embodiments, signals from motion sensors can be used to confirm whether one or both atria are in AF, or whether P-wave detection parameters, such as detection sensitivity parameters or P-wave blanking period, should be adjusted.

[0020] For example, when no far-field P wave is detected, mechanical activity can be used to determine whether the patient's heart is in AF based on accompanying measurements. Specifically, cardiac treatment systems can use motion sensors to measure mechanical activity to determine whether the patient's heart is in AF. Based on the AF determination, the system can be configured to switch modes or adjust the P wave sensitivity level to better detect far-field P waves when the patient's heart is not in AF.

[0021] As used herein, the term "or" is generally used in its inclusive sense, such as meaning "and / or," unless the context clearly specifies otherwise. The term "and / or" refers to one or all elements or a combination of at least two elements.

[0022] The accompanying drawings of this disclosure depict one or more aspects described herein. However, other aspects not depicted in the drawings also fall within the scope of this disclosure. The same numerals may be used in the drawings to denote the same parts, steps, or other elements. However, the use of a reference character to denote an element in a given drawing is not intended to limit elements in another drawing labeled with the same reference character, and vice versa; the use of different reference characters to denote elements in different drawings is not intended to indicate that elements referenced differently cannot be identical or similar.

[0023] Figure 1 This is an example of a cardiac treatment system 100 used with patient 102. The systems, devices, and techniques described in this disclosure provide mode switching that is robust enough to be used with far-field sensing, such as atrial activation. Typically, system 100 may include one or more implantable medical devices (IMDs) to perform cardiac treatments with mode switching capabilities. Each IMD may be configured to detect electrical activity in one or more chambers of patient's heart 108. One or more IMDs may be used to detect ventricular electrical activity, atrial electrical activity, and mechanical activity in one or more chambers. In particular, one or more electrodes may be used to sense or detect electrical activity, and one or more motion sensors may be used to sense or detect mechanical activity.

[0024] One or more IMDs of system 100 may include leadless or led IMDs. As used herein, a “leadless” device refers to a device that does not have leads extending out of the patient’s heart 108. In other words, a leadless device may have leads that do not extend from the outside of the patient’s heart 108 into the inside of the patient’s heart. Some leadless devices may be introduced via a vein, but once implanted, the device does not contain or may not contain any transvenous leads and may be configured to provide cardiac therapy without the use of any transvenous leads. In one example, in particular, a leadless device implanted in the left ventricle (LV) does not use leads to be operatively connected to electrodes in the LV when the housing of the device is positioned in the LV.

[0025] System 100 may include one or more intracardiac IMDs. As used herein, an "intracardiac" device refers to a device configured to be fully implanted within the heart 108. An intracardiac IMD may include leads that do not extend out of the patient's heart 108.

[0026] The first electrode of system 100 can be configured to sense the electrical activity of one or both ventricles (left, right, or both) of the patient's heart 108, or to deliver cardiac therapy to a specific ventricle of the patient's heart. The second electrode of system 100 can be configured to sense the electrical activity of the atria of the patient's heart 108. In some cases, the second electrode can also be configured to deliver cardiac therapy to a specific atrium of the patient's heart 108.

[0027] One or more leadless electrodes may be coupled to the housing of the IMD. An IMD having only leadless electrodes can be described as a leadless IMD. As used herein, a "leadless" electrode refers to an electrode operatively coupled to the device that has no leads or does not use leads, extending between the electrode and the housing of the device. In some embodiments, the first medical device 104 employs a leadless MICRA similar to that implanted in an LV. TM In the form of the leadless MICRA TM Available from Medtronic plc in Dublin, Ireland.

[0028] The motion sensor of system 100 can be configured to sense the mechanical activity of a patient's heart 108. In some cases, the motion sensor can be configured to sense at least the mechanical activity of one or both atria (left, right, or both) of the patient's heart 108. The motion sensor used can be related to... Figure 2 The motion sensor 11 described is the same as or similar to the one described.

[0029] The controller of system 100 (which may include processing circuitry) can be operatively coupled to one or more electrodes and to a motion sensor. The operative coupling can be made using wired or wireless connections. Using one or more electrodes and a motion sensor, the controller can be configured to deliver pacing to at least one ventricle of the patient's heart 108 using a first electrode, based on dual-chamber sensing in dual-chamber sensing mode or single-chamber sensing in single-chamber sensing mode. The controller can also be configured to determine whether electrical activity of at least one atrium sensed by a second electrode indicates AF. The controller can also be configured to determine, for example, whether mechanical activity of the patient's heart 108 sensed by the motion sensor indicates AF, in response to determining that electrical activity of one or both atria indicates AF. Mechanical activity may represent atrial contraction. A patient's atrial contraction may be referred to as "atrial pumping." The absence of atrial pumping may indicate AF. Furthermore, the controller can be configured to deliver suppressed pacing using the first electrode, for example, in response to determining that mechanical activity of the patient's heart 108 indicates AF (or does not indicate atrial contraction or atrial pumping).

[0030] In one implementation, system 100 may consist of only one implantable intracardiac or leadless IMD (e.g., implantable in the right atrium (RA) facing the left LV) Figure 2 The intracardiac or leadless IMD may include a first electrode implantable to sense the near-field electrical activity of the LV of the patient's heart 108 or to deliver cardiac therapy to the LV of the patient's heart. The intracardiac or leadless IMD may also include a second electrode implantable to sense the near-field electrical activity of the RA of the patient's heart 108 or to deliver cardiac therapy to the RA of the patient's heart.

[0031] In another implementation, system 100 may consist of only one implanted intracardiac or leadless IMD (such as...) in the LV. Figure 1 The first medical device 104). The intracardiac or leadless IMD may include a first electrode implantable to sense near-field electrical activity of the LV of a patient's heart 108 or to deliver cardiac therapy to the LV of a patient's heart. The intracardiac or leadless IMD may also include a second electrode implantable to sense far-field electrical activity of the RA of a patient's heart 108.

[0032] In another embodiment, system 100 may include an intracardiac or leadless IMD and a leaded IMD (such as... Figure 1The first medical device 104 and the second medical device 106). An intracardiac or leadless IMD may be implanted in the LV and include a first electrode to sense the electrical activity of the LV of the patient's heart 108 or to deliver cardiac treatment to the LV of the patient's heart. A led IMD may include a second electrode to sense the electrical activity of the RA of the patient's heart 108 or to deliver cardiac treatment to the RA of the patient's heart. A led IMD may be configured to transmit at least the atrial activation time to the intracardiac or leadless IMD.

[0033] System 100 may include one or both of a first medical device 104 and a second medical device 106. Any suitable medical device may be used for the first medical device 104 and the second medical device 106. For example, the first medical device 104 or the second medical device 106 may represent a defibrillator, a cardiac resynchronization pacemaker / defibrillator, or a pacemaker. The first medical device 104 and the second medical device 106 may be referred to as an IMD. In the illustrated embodiment, one or both of the first medical device 104 and the second medical device 106 may be configured to deliver pacing therapy, such as delivering pacing therapy to the right ventricle and left ventricle of the heart 108, respectively, to provide CRT pacing.

[0034] Typically, when using two or more medical devices, these devices can be implanted in different chambers of the patient's heart 108. As shown, the first medical device 104 is a leadless IMD implanted in the LV of the patient 102, while the second medical device 106 is a led IMD with a leaded electrode implanted in each of the RA and right ventricle (RV) of the patient's heart.

[0035] The first medical device 104 may be a leadless IMD inside the patient's heart 108. The first medical device 104 may also be referred to as an intracardiac IMD. The first medical device 104 may be referred to as a left-side IMD implanted on the left side of the patient's heart 108. In some embodiments, one or more IMDs similar to the first medical device 104 (…) Figure 1 (Not shown) It may be implanted additionally or alternatively into other chambers of the heart 108 or attached to the epicardium of the heart.

[0036] The first medical device 104 may be configured to sense electrical activity of the heart 108 and deliver pacing therapy, such as CRT, to the heart 108. The first medical device 104 may be attached to the inner wall of the heart 108 via one or more fixation elements that penetrate the tissue. These fixation elements may secure the first medical device 104 to the cardiac tissue and hold electrodes (e.g., cathodes or anodes) on the housing of the first medical device, in contact with cardiac tissue such as the endocardium or myocardium. In addition to delivering pacing pulses, the first medical device 104 may be configured to sense or monitor electrical activity in one or more forms of electrical signals using electrodes carried on the housing of the first medical device 104. The electrical activity may be generated by the myocardium and indicates depolarization and repolarization of the heart 108 at different times during the cardiac cycle.

[0037] The second medical device 106 may include a housing coupled to one or both of the ventricular lead 110 and the atrial lead 112. In various embodiments, the second medical device 106 is an implantable cardioverter-defibrillator (ICD) capable of delivering pacing, cardioversion, and defibrillation therapy to the heart 108. In particular, the second medical device 106 may be an extravascular ICD (EVICD) with a vascular housing. The ventricular lead 110 and the atrial lead 112 may be operatively coupled or electrically coupled to the housing of the second medical device 106 and extend into the patient's heart 108. The ventricular lead 110 may include electrodes on the lead located in the patient's RV (ventricular ventricle). Figure 1 (Not labeled), used to sense ventricular electrogram (EGM) signals and pacing in the RV. Atrial leads 112 include electrodes on the leads located in the patient's RA (radial artery apnea). Figure 1 (Not shown in the image) for sensing atrial EGM signals and pacing in RA. Ventricular lead 110 or atrial lead 112 may also include coil electrodes for delivering cardioversion and defibrillation shocks. The second medical device 106 may also include one or more electrodes on its housing.

[0038] The first medical device 104, the second medical device 106, the ventricular lead 110, or the atrial lead 112 can be used to acquire near-field or far-field cardiac EGM signals from the patient 102 and to deliver cardiac treatment in response to the acquired data. In some embodiments, the sensed electrical activity of one of the atria can be based on one or more far-field measurements sensed by one of the electrodes coupled to the first medical device 104, the second medical device 106, the ventricular lead 110, or the atrial lead 112. For example, a housing-based electrode coupled to the first medical device 104, a housing-based electrode coupled to the second medical device 106, or the ventricular lead 110 can be used to detect far-field atrial signals, such as far-field P-wave signals. In another example, one or more devices or leads can be used to detect far-field intrinsic ventricular activation signals.

[0039] The second medical device 106 is shown configured for a dual-chamber IMD configuration, but other examples may include one or more additional leads, such as coronary sinus leads extending into the RA, through the coronary sinus and into the cardiac vein, to position electrodes along the LV for sensing LV EGM signals and delivering pacing pulses to the LV.

[0040] In some embodiments, the second medical device 106 may be configured for a single-chamber IMD system, or otherwise exclude the atrial lead 112. In such embodiments, the cardiac treatment system 100 may not be able to obtain near-field EGM signals from one or both atria. The first medical device 104 or the second medical device 106 may be used to detect far-field EGM signals from one or both atria.

[0041] Processing circuitry, sensing circuitry, and other circuitry configured to perform the techniques described herein with respect to the first medical device 104 and the second medical device 106 may be housed within a respective sealed housing. The housing (or a portion thereof) may be conductive to serve as an electrode for pacing or sensing, or as an active electrode during defibrillation. Thus, the housing of some IMDs may be referred to as including housing electrodes or housing-based electrodes.

[0042] In some examples, the first medical device 104 and the second medical device 106 can engage in wireless communication to facilitate this coordinated activity. The communication can be one-way or two-way. In some embodiments, the wireless communication can utilize distinctive signaling or triggering electrical pulses provided by electrodes of the first medical device 104, which are conducted through the patient's tissue and detectable by the second medical device 106, and vice versa. The wireless communication can use a communication interface that may include an antenna to provide electromagnetic radiation that propagates through the patient's tissue and is detectable, for example, using the communication interface of another IMD.

[0043] In various embodiments, one or both of the first medical device 104 and the second medical device 106 are configured to communicate wirelessly or wiredly with the external device 116.

[0044] The first medical device 104 or the second medical device 106 can transmit EGM signal data, cardiac rhythm event data, or data regarding treatment delivery to the external device 116. In various embodiments, the external device 116 can be a computing device, such as one used in a home, outpatient, clinic, or hospital setting, for wireless or wired telemetry communication. The external device 116 can be coupled to remote patient monitoring, such as that available from Medtronic plc in Dublin, Ireland. External device 116 may be, for example, a programmer, an external monitor, or a consumer device such as a smartphone.

[0045] External device 116 can be used to program commands or operating parameters into the first medical device 104 or the second medical device 106 to control the functions of these devices. Typically, external device 116 can be used to interrogate these devices to retrieve data, including device operating data and physiological or neural data accumulated in the memory of either of these devices. Interrogation can be automatic, such as according to a schedule, or in response to commands from a remote or local user. One or more of these external devices may also be referred to as an “instrument” or a group of instruments. External device 116 can be included as part of a recharging system configured to recharge the battery or other power source supplied within the first medical device 104 or the second medical device 106.

[0046] The cardiac treatment system 100 may also include a transceiver 118, which is coupled to communicate wirelessly or wiredly with the first medical device 104 or the second medical device 106. In some embodiments, the transceiver 118 may be referred to as an access point, such as a network, providing a communication link between the first medical device 104 and the second medical device 106. The transceiver 118 may use communication technologies similar to those used with other devices and may be included as part of a recharging system.

[0047] The first medical device 104 and the second medical device 106 may be configured to coordinate their cardiac rhythm detection and treatment activities. In some embodiments, the second medical device 106 is operatively coupled to the first medical device 104 to transmit the atrial activation time to the first medical device, thereby delivering pacing from the first medical device based on the atrial activation time.

[0048] For example, a leadless resynchronization pacing device, such as a first medical device 104 implanted in the left ventricle (LV), can communicate with a second medical device 106 or a right-side implanted system or extravascular system (e.g., EVICD). The second medical device 106 can be used to sense atrial electrical activity, which can trigger the first medical device 104 to pace with a predetermined AV delay after intrinsic atrial activation or an atrial sensing event (e.g., a P wave). When the second medical device 106 does not directly sense atrial electrical activity and uses, for example, far-field P wave sensing technology, the P wave may be more difficult to sense accurately during AF. The cardiac treatment system 100 can be configured to switch modes upon detection of AF, such as from VDD / DDD mode to VVI mode. In this case, accompanying measurements can help confirm the presence of AF and thus help the cardiac treatment system 100 to correctly perform mode switching. In some embodiments, the first medical device 104 may include a motion sensor. Mechanical activity detected by the motion sensor can be used as an accompanying measurement to facilitate AF detection.

[0049] Figure 2 An example of the anatomy of an intracardiac or leadless implantable medical device 140 and a patient's heart 108 that can be used with the cardiac treatment system of this disclosure is shown. Device 140 may be identical or similar to the first medical device 104, except that device 140 is implanted from the Koch's triangle in the RA into the LV, rather than implanted within the LV. One or more features described with respect to device 140 may also be used with the first medical device 104 or even with a leaded IMD. For example, device 140 may be used alone or in conjunction with a second medical device 106 as an alternative to or supplement to the first device 104.

[0050] In other embodiments (not shown), IMD 140 may be replaced by a leaded device coupled to an implantable medical lead (which may be similar to lead 110 or lead 112) and may be coupled to a second IMD, such as device 106, or may be coupled to an external device, such as device 116. An example of a leaded device is described in U.S. Patent Application No. 62 / 805,749 (Yang et al.), filed February 14, 2019, entitled “Lead-in-lead systems and methods for cardiac therapy,” which is incorporated herein by reference. Motion sensor 11 may be integrated into, for example, the distal end portion or distal tip of the leaded device to detect mechanical activity of the heart rather than non-inherent motion. In some embodiments, the distal end portion or distal tip of the leaded device may have a small piezoelectric sensor in motion sensor 11 configured to detect myocardial motion.

[0051] The intracardiac IMD 140 may include a housing 30. The housing 30 may define a hermetically sealed cavity in which internal components of the device 140 reside, such as sensing circuitry, therapy delivery circuitry, control circuitry, memory, telemetry circuitry (or communication interface), other optional sensors, and a power supply. The housing 30 may be at least partially formed of a conductive material. Alternatively, the housing 30 may be at least partially formed of a non-conductive material.

[0052] The housing 30 can be described as extending in a generally cylindrical shape between a distal end region 32 and a proximal end region 34 for ease of delivery. The housing 30 may include, for example, a delivery tool interface member 26 at the proximal end 34 for engagement with a delivery tool during implantation of the device 140. For example, the delivery tool interface member 26 may be used when advancing the device 140 toward the target implantation region 4 using a delivery catheter.

[0053] All or part of the housing 30 can be used as an electrode during cardiac therapy, such as in sensing and / or pacing. In the example shown, the housing-based electrode 24 is shown as a proximal portion of the outer housing 30. When the housing 30 comprises a conductive material (e.g., formed of a conductive material), portions of the housing 30 can be electrically insulated by a non-conductive material (such as a coating), thereby exposing one or more discrete regions of the conductive material to define the housing-based proximal electrode 24. When the housing 30 comprises a non-conductive material (e.g., formed of a non-conductive material), a conductive coating or layer can be applied to one or more discrete regions of the housing 30 to form the housing-based proximal electrode 24. In other examples, the housing-based proximal electrode 24 can be a component mounted or assembled onto the housing 30, such as a ring electrode. When the housing 30 comprises a non-conductive material, the housing-based proximal electrode 24 can be electrically connected to the internal circuitry of the device 140, for example, via the conductive housing 30 or an electrical conductor.

[0054] In the example shown, the housing-based electrode 24 is positioned closer to the proximal end region 34 of the housing than the distal end region 32 of the housing, and can therefore be described as a proximal housing-based electrode. However, in other examples, the housing-based electrode 24 may be located at other locations along the housing 30, for example, relatively more distally than the location shown.

[0055] At the distal end region 32, the device 140 may include a distal fixation and electrode assembly 36, which may include one or more fixation members 20 in addition to one or more dart electrodes 12 of equal or unequal length. The one or more dart electrodes 12 of the assembly 36 may be described as tissue puncture electrodes. In other embodiments (not shown), the distal fixation and electrode assembly 36 may include a helical or spiral electrode. The dart electrode or spiral electrode may also be described as a tissue puncture electrode.

[0056] As depicted, the device 140 includes a single dart electrode 12, which may include a shaft 40 extending distally away from the distal end region 32 of the housing, and may include one or more electrode elements, such as a tip electrode element 42 at or near the free distal end region of the shaft 40. The tip electrode element 42 may have a conical or hemispherical distal tip with a relatively narrow tip diameter (e.g., less than about 1 millimeter (mm)) for penetration into and through the tissue layer without using a sharp or needle-like tip with a pointed or slanted edge.

[0057] The shaft 40 of the dart electrode 12 can be a normally straight member and can be rigid. In other embodiments, the shaft 40 can be described as relatively rigid but still having limited flexibility (e.g., elastic or semi-rigid) in the lateral direction. The dart electrode 12 can be configured to pierce one or more tissue layers to position the tip electrode element 42 within a desired tissue layer (e.g., ventricular myocardium). Thus, the length or height 47 of the shaft 40 can correspond to the intended pacing site depth. If a second dart electrode 12 is used, its length or height may not be equal to the intended pacing site depth and can be configured to act as an independent electrode for delivering pacing energy to the tissue.

[0058] One or more fixation members 20 may be described as one or more “teeth” having a normal bending position. The teeth may be held in a distally extended position within the delivery tool. The distal tip of the teeth may penetrate cardiac tissue to a limited depth before elastically bending proximally back to the normal bending position (shown) upon release from the delivery tool.

[0059] In some examples, the distal fixation and electrode assembly 36 includes a housing-based distal electrode 22. When the device 140 is used as a pacemaker for multi-chamber pacing (e.g., dual-chamber or triple-chamber pacing) and sensing, the tip electrode element 42 can be used as a cathode electrode paired with the housing-based proximal electrode 24, which serves as a return anode electrode. Alternatively, the housing-based distal electrode 22 can be used as a return anode electrode paired with the tip electrode element 42 for sensing ventricular signals and delivering ventricular pacing pulses. In other examples, the housing-based distal electrode 22 can be a cathode electrode for sensing atrial signals and delivering pacing pulses to the atrial myocardium in the target implantation region 4. When the housing-based distal electrode 22 is used as an atrial cathode electrode, the housing-based proximal electrode 24 can be used as a return anode paired with the tip electrode element 42 for ventricular pacing and sensing, and as a return anode paired with the housing-based distal electrode 22 for atrial pacing and sensing.

[0060] As illustrated, in some pacing applications, the target implantation region 4 is along the atrial endocardium 18, typically below the AV node 15 and His bundle 5. The dart electrode 42 may define the length or height 47 of its axis 40 for penetration through the atrial endocardium 18 in the target implantation region 4, through the central fiber body 16, and into the ventricular myocardium 14, without penetrating through the ventricular endocardial surface 17. When the length or height 47 of the dart electrode 12 is fully advanced into the target implantation region 4, the tip electrode element 42 may rest or be positioned within the ventricular myocardium 14, and the distal electrode 22, based on the housing, may be positioned in close contact with or very close to the atrial endocardium 18.

[0061] Device 140 (as shown) and devices 104, 106 may include a motion sensor 11 or motion detector that can be housed within housing 30. Motion sensor 11 can be used to monitor mechanical activity, such as atrial mechanical activity (e.g., atrial contraction) and / or ventricular mechanical activity (e.g., ventricular contraction). In some embodiments, motion sensor 11 can be used to detect RA mechanical activity. Non-limiting examples of motion sensor 11 include an accelerometer. In some embodiments, the mechanical activity detected by motion sensor 11 can be used to supplement or replace electrical activity detected by one or more electrodes of device 140. For example, motion sensor 11 can be used in addition to, or as an alternative to, the housing-based proximal electrode 24.

[0062] The mechanical activity detected by motion sensor 11 can correspond to various heart sounds. Typically, heart sounds are associated with the mechanical vibrations of the patient's heart and the flow of blood through the heart valves, and therefore can be highly correlated with pressure gradients and blood pressure across the heart valves. Heart sounds may be due not only to vibrations and pressure within the heart, but also to the entire cardiac circulatory system, such as blood, the heart, aorta, etc. Heart sounds can be reproduced with each cardiac cycle and are separated and classified according to the activity associated with the vibration.

[0063] The first heart sound is called "S1" and can be considered as the vibrational sound produced by the heart during the closure of the atrioventricular or AV valves (i.e., the mitral and tricuspid valves). The S1 sound can sometimes be decomposed into an M1 sound component from the closure of the mitral valve and a T1 sound component from the closure of the tricuspid valve. The second heart sound is called "S2" and is produced by the closure of the semilunar valves (i.e., the pulmonary and aortic valves). The S2 heart sound can be considered as marking the beginning of diastole. The S2 sound can also be decomposed into components. The P2 sound component comes from the closure of the pulmonary valve, and the A2 sound component comes from the closure of the aortic valve. The third and fourth heart sounds are called "S3" and "S4," respectively, and can be conceptualized as relating to the filling of the ventricles during diastole. S3 is caused by the rapid filling of the ventricles, which occurs when a large amount of blood flows from the atria into the ventricles without the ventricular walls relaxing. S4 is caused by the rapid filling of the ventricles with blood from the atria due to atrial contraction.

[0064] The device 140 can be implanted such that the electrode 12 is positioned to sense electrical activity or deliver pacing therapy to a specific part of the patient's LV myocardium. For example, the electrode 12 can be implanted in the basal region, septal region, or baso-septal region of the LV.

[0065] Figure 3This is a two-dimensional (2D) ventricular mapping 60 (e.g., top view) of a patient's heart, showing LV 62 and RV 64 in a standard 17-segment view. Mapping 60 includes multiple regions 68 corresponding to different areas of the human heart. As shown, regions 68 are numerically labeled 1-17 (which, for example, correspond to the standard 17-segment model of the human heart, corresponding to the 17 segments of the left ventricle of the human heart, etc.). Regions 68 of mapping 60 may include the anterior basal region 1, the anterior basal septal region 2, the infrabasal septal region 3, the subbasal region 4, the lateral basal region 5, the anterolateral basal region 6, the anterior midline region 7, the anterior midline septal region 8, the inframidal midline septal region 9, the inframidal midline region 10, the inframidal midline region 11, the anterolateral midline region 12, the anterior apical region 13, the apical septal region 14, the infraapical region 15, the lateral apical region 16, and the apical region 17. The infraseptal and anterior septal regions of the right ventricle 64, as well as the right bundle branch (RBB) and left bundle branch (LBB), are also shown.

[0066] In some embodiments, any tissue biopsy electrode of this disclosure may be implanted in the base and / or septal region of the LV myocardium of a patient's heart. In particular, the tissue biopsy electrode may be implanted from the Koch's triangle of the RA through the RA endocardium and central fibrous tissue.

[0067] Once implanted, the tissue puncture electrode can be positioned in the target implantation area 4 ( Figure 2 In this context, the basal and / or septal regions, such as those of the LV myocardium, are included. Referring to Figure 60, the basal region includes one or more of the following: prebasal region 1, prebasal septal region 2, subbasal septal region 3, subbasal region 4, pre-intermediate region 7, pre-intermediate septal region 8, sub-intermediate septal region 9, and sub-intermediate region 10. Referring to Figure 60, the septal region includes one or more of the following: prebasal septal region 2, prebasal septal region 3, pre-intermediate septal region 8, sub-intermediate septal region 9, and apical septal region 14.

[0068] In some implementations, such as Figure 2 The tissue puncture electrode of the implantable medical device 140 can be positioned in the basal septal region of the LV myocardium during implantation. The basal septal region may include one or more of the following: the preseptal region 2, the subseptal region 3, the preseptal region 8, and the subseptal region 9.

[0069] In some implementations, upon implantation, the tissue puncture electrode can be positioned in the upper / posterior basal septal region of the LV myocardium. The upper / posterior basal septal region of the LV myocardium may include a portion of at least one of the subbasal septal region 3 and the intermediate subseptal region 9. For example, the upper / posterior basal septal region may include region 66, which is typically shown as a dashed boundary. As illustrated, the dashed boundary represents the approximate location of the upper / posterior basal septal region and may vary slightly in shape or size depending on the specific application. Without being bound by any particular theory, intraventricular synchronous pacing and / or activation may result from stimulation of the septal ventricular myocardium due to the functional electrical connection between the subendocardial Purkinje fibers and the ventricular myocardium.

[0070] Although Figures 1 to 2 Specific devices, such as devices 104, 106, and 140, are shown, but the technology disclosed herein can be used with any suitable cardiac treatment system. Such suitable cardiac treatment systems typically include a controller.

[0071] Figure 4 An example of a cardiac treatment system is shown, including a controller 160 that can be used with various IMDs of this disclosure. The controller 160 is operatively coupled to a first electrode 162, a motion sensor 164, and a second electrode 166. In particular, the controller 160 may include a processor 170, a memory 172 operatively coupled to the processor, and a communication interface 174 or input / output interface operatively coupled to the processor and the first electrode 162, motion sensor 164, and second electrode 166.

[0072] Typically, the various components of controller 160 can be housed in a first medical device, a second medical device, another medical device, or any combination of these devices. In some embodiments, the first electrode 162 and motion sensor 164 can be coupled to the housing of the first medical device. The second electrode 166 can be coupled to the housing of a second medical device separate from the first medical device. While various operable connections are envisioned, in some embodiments, the first electrode 162 and motion sensor 164 can be coupled to communication interface 174 using a wired connection. The second electrode 166 can be coupled to communication interface 174 using a wireless connection. Electrical signal pulses delivered through the patient's body can also be used. In other embodiments, the first electrode 162, motion sensor 164, and second electrode 166 are coupled to the housing of a single IMD and coupled using a wired connection.

[0073] One or more components of the apparatus described herein (such as controllers, interfaces, or sensors) may include a processor, such as a central processing unit (CPU), a computer, a logic array, or other means capable of introducing or extracting data into or out of the apparatus. Typically, a controller may include one or more computing devices having memory, processing, and communication hardware. The controller may include circuitry for connecting the various components of the controller together or to other components operatively coupled to the controller. The functionality of the controller may be performed by hardware and / or as computer instructions on a non-transient computer-readable storage medium.

[0074] The processor of the controller may include any one or more of a microprocessor, microcontroller, digital signal processor (DSP), application-specific integrated circuit (ASIC), field-programmable gate array (FPGA), and / or equivalent discrete or integrated logic circuitry. In some examples, the processor may include multiple components, such as one or more microprocessors, one or more controllers, one or more DSPs, one or more ASICs, and / or one or more FPGAs, and any combination of other discrete or integrated logic circuitry. The functionality attributed herein to the controller or processor may be implemented as software, firmware, hardware, or any combination thereof. Although this document describes a processor-based system, alternative controllers may utilize other components such as relays and timers, either alone or in combination with a microprocessor-based system, to achieve the desired results.

[0075] In one or more embodiments, exemplary systems, apparatuses, methods, and other functions may be implemented using one or more computer programs employing a computing device, which may include one or more processors and / or memory. The program code and / or logic described herein may be applied to input data / information to perform the functions described herein and generate desired output data / information. Output data / information may be applied as input to one or more other apparatuses and / or methods, as described herein or applied in a known manner. The controller functions described herein may be implemented in any manner known to those skilled in the art that benefits from this disclosure.

[0076] The cardiac treatment system disclosed herein can perform various functions to perform mode switching. For example, the cardiac treatment system can detect AF and switch modes accordingly between or within multiple different pacing modes. In some embodiments, the cardiac treatment system can switch between a dual-chamber sensing mode (e.g., VDD or DDD) and a single-chamber sensing mode (e.g., VVI) depending on whether AF has been detected.

[0077] Figure 5An example of a mode switching method 200 during cardiac treatment delivery that can be used with the cardiac treatment system of this disclosure is shown. Typically, method 200 facilitates mode switching between VDD or DDD (VDD / DDD) mode and VVI mode. Switching detection can be performed at any suitable rate. In some embodiments, method 200 is performed for each cardiac cycle. In other embodiments, method 200 is performed periodically (e.g., every 5 cardiac cycles, every 10 cardiac cycles, every 1 second, every 2 seconds, every 5 seconds, etc.).

[0078] VDD refers to a mode of cardiac therapy system configured to sense atrial and ventricular activity, such as electrical activation or other events, and to pace only one or both ventricles. This mode can be used, for example, in patients with a normal sinus rhythm but AV block. DDD refers to a mode of cardiac therapy system configured to sense activity and pace one or both atria as needed. as well as Pacing is delivered to one or both ventricles. VVI refers to a mode of cardiac therapy system configured to pace one or both ventricles in response to irregular intrinsic ventricular rhythms (e.g., below-threshold ventricular rhythms). VDD / DDD mode can be referred to as a pacing mode using dual-chamber sensing. VVI mode can be referred to as a pacing mode using single-chamber sensing.

[0079] Method 200 may include delivering cardiac therapy in VDD / DDD mode 202. In some embodiments, P wave sensing and / or atrial expulsion may be used to trigger pacing in VDD / DDD mode. The P wave may indicate atrial activation or other events.

[0080] Method 200 may include determining whether a patient's heart is experiencing atrial fibrillation (AF) 204. This determination may be made using monitored electrical or mechanical activity of the patient's heart, or some combination of these measurements. In some embodiments, at least one measurement of electrical activity and at least one measurement of mechanical activity are used to determine whether the patient's heart is experiencing AF. The determination 204 may be performed periodically once or multiple times, or triggered, for example, by the detection of the absence of a near-field or far-field P wave.

[0081] Method 200 may also include delivering cardiac treatment in VVI mode 206 in response to determining that the patient's heart is experiencing AF. In response to determining that the patient's heart is not experiencing AF, method 200 may return to or continue delivering cardiac treatment in VDD / DDD mode 202.

[0082] Far-field sensing of the P wave can be challenging in VDD / DDD mode due to its smaller amplitude. This problem can be further complicated when the patient enters AF, as the P wave may become even smaller and more difficult to pick up. Mechanical activity can facilitate confirmation that atrial activation has occurred. In particular, atrial expulsion typically occurs after activation of the normal or paced atrial system. Atrial expulsion can manifest as discernible amplitude changes in mechanical activity, for example, sensed by an integrated accelerometer.

[0083] Figure 6 It shows what can be used to implement Figure 5 Method 200 is an example of a specific approach for determining whether cardiac treatment is delivered in VDD / DDD mode 202 or VVI mode 206, particularly when using far-field P waves. As shown, method 300 may include determining whether atrial activation 302 has been detected, which can provide an indication of the possible presence of AF, while delivering cardiac treatment in VDD / DDD mode 202 using dual-chamber sensing. An example of detecting atrial activation includes detecting P waves. Method 300 may, for example, continue delivering cardiac treatment in VDD / DDD mode 202 in response to the detection of a P wave in sensed electrical activity.

[0084] When no P wave is detected, AF may be present. In other words, the absence of a P wave can indicate AF. Method 300 can pause or suppress pacing and detect intrinsic ventricular electrical activity 304, for example, detecting intrinsic ventricular excitation in response to determining that no P wave is detected.

[0085] In the absence of a detected P wave, the system can determine the presence of mechanical artifacts of atrial activation, such as atrial expulsion. Method 300 can, for example, determine a peak 306 in the motion sensor signal within a time window in response to determining inherent ventricular electrical activity. In some embodiments, the peak in the motion sensor signal can indicate mechanical activity corresponding to the S4 heart sound, which may be referred to as the A4 signal. Method 300 can then include, for example, determining whether atrial expulsion has been detected based on the peak and a threshold 308. For example, the amplitude of the peak can be compared to a threshold. In some embodiments, a small peak below the threshold indicates that a P wave is not present or is unlikely to appear in the far-field signal, for example, because the patient's heart is in AF.

[0086] In the absence of atrial pumping, the system can determine that AF is not present. Method 300 may include, for example, switching to VVI mode 206 using single-chamber sensing in response to determining that no atrial pumping has been detected. The next cardiac cycle can be paced in VVI mode 206. Method 300 may return or continue to determine whether a P wave 302 has been detected. If a P wave has been detected, method 300 may switch back to VDD / DDD mode 202.

[0087] When atrial blood flow is detected without a detected P wave, the system can adjust the P wave detection technique to reduce false negatives in P wave detection or false positives in possible AF detection. Method 300 can, for example, adjust the P wave detection sensitivity or blanking period 310 in response to determining that atrial blood flow has been detected. The P wave detection sensitivity can also be referred to as the atrial activation threshold, such as based on the amplitude of the expected peak where the P wave is located, to detect the P wave. Sensitivity can be based on the amplitude of electrical activity or the amplitude difference or temporal gradient of amplitude within the sensing time window (e.g., a slope threshold). Method 300 can return to or continue using the adjusted sensitivity or blanking period in VDD / DDD mode 202 to deliver cardiac treatment. These adjustments to sensitivity or blanking can help detect P waves more accurately and thus help detect AF more accurately using sensed electrical activity.

[0088] As used in this article, the term "blank period" refers to a period of time or pattern during which a device does not sense any electrical or mechanical activity, which can help avoid cross-interference or oversensing.

[0089] With various technologies described, Figure 7 An example graph 400 showing electrical activity and mechanical activity signals is provided; various techniques can be used for these signals. Electrical activity signal 402 can be acquired by any suitable method. In some embodiments, electrical activity signal 402 is an EGM signal. Mechanical activity signal 404 can be acquired by any suitable method. In some embodiments, mechanical activity signal 404 is an accelerometer signal from a motion sensor coupled to the patient's heart. In one example, mechanical activity signal 404 is obtained from a motion sensor implanted in the ventricle or atrium. The motion sensor can be coupled to a leadless or intracardiac IMD.

[0090] In one example, the electrical activity signal 402 can be obtained from a near-field signal detected by an electrode implanted in the atrium. In another example, the electrical activity signal 402 can be obtained from a far-field signal detected by an electrode implanted in the ventricle. The electrode used to detect the electrical activity signal 402 can be coupled to a leaded or leadless IMD, which may or may not be an intracardiac IMD.

[0091] Electrical activity signal 402 may or may not include a P wave 406. If a P wave 406 is present, the implantable medical system may continue pacing using VDD / DDD pacing, or may switch to VDD / DDD pacing. If a P wave 406 is absent, the implantable medical system may examine to confirm whether the patient has AF. Any suitable technique can be used to detect the P wave, such as detecting the peak and comparing the peak to a minimum amplitude threshold. Any suitable technique for P wave sensing and detection can be used, including, for example, the technique described in U.S. Patent No. 10,342,981 (Ghosh et al.), published July 9, 2019, entitled "Far-field P-wave sensing in near real-time for timing delivery of pacing therapy in a cardiac medical device and medical device system".

[0092] In one example, if the P wave 406 is absent, the system can suppress pacing and, instead of pacing, detect intrinsic ventricular activation 408, which can be represented as the start of a QRS complex on the electrical activity signal 402. The timestamp of intrinsic ventricular activation can be labeled with a timestamp.

[0093] The corresponding mechanical activity signal 404 can be examined within a time window 410 that begins earlier than the inherent ventricular activation, and this time window may immediately precede the timestamp. For example, the time window 410 may have a duration of less than or equal to 100 ms, 125 ms, 150 ms, 175 ms, or 200 ms. In one example, the time window 410 is equal to 150 ms. The system can determine whether atrial expulsion 412 (or the A4 signal corresponding to the S4 heart sound) is present in the mechanical activity signal 404 within the time window 410.

[0094] For example, atrial expulsion 412 can be detected when the mechanical activity signal 404 exceeds a minimum amplitude threshold. The minimum amplitude threshold can be set, for example, based on the logarithm of previous amplitudes of atrial expulsion during VDD / DDD pacing. The minimum amplitude threshold can also be based on the average atrial expulsion amplitude and standard deviation of recorded or historical amplitudes. In one example, the minimum amplitude threshold could be equal to the average atrial expulsion amplitude minus two standard deviations.

[0095] If atrial expulsion 412 is present, the system can continue pacing using VDD / DDD pacing, or can switch to VDD / DDD pacing. Additionally, for example, the sensitivity of P wave detection or one or both of the blanking periods associated with P wave detection can be adjusted to minimize false negative detections of P wave 406. If atrial expulsion 412 is absent, the system can switch to VVI pacing for the next cardiac cycle until, for example, one or both of P wave and atrial expulsion appear in the corresponding signal.

[0096] Exemplary implementation plan

[0097] While this disclosure is not limited thereto, an understanding of various aspects of this disclosure will be gained through discussion of the specific illustrative embodiments provided below. Various modifications to the exemplary embodiments and additional embodiments of this disclosure will become apparent herein.

[0098] In implementation scheme A1, one method includes:

[0099] Determine if electrical activity indicates atrial fibrillation;

[0100] Determine if mechanical activity indicates atrial fibrillation; and

[0101] The pacing parameters or mode are adjusted based on whether the electrical and mechanical activity indicates atrial fibrillation.

[0102] In implementation scheme A2, a method includes the method according to implementation scheme A1, wherein the electrical activity includes the electrical activity of one or both atria of a patient's heart based on far-field measurements.

[0103] In implementation scheme A3, a method includes the method according to any of the preceding implementation schemes A, wherein determining whether electrical activity indicates atrial fibrillation includes determining whether a P wave is detected.

[0104] In implementation scheme A4, a method includes the method according to any of the preceding implementation schemes A, wherein the mechanical activity includes mechanical activity of the patient's heart corresponding to the S4 heart sound.

[0105] In embodiment A5, a computer-readable medium includes instructions stored thereon that, when executed, cause a processor to perform the method according to any of the preceding embodiments A.

[0106] In implementation scheme B1, an implantable medical system includes:

[0107] A first electrode is used to sense the electrical activity of one or two ventricles of a patient's heart or to deliver cardiac treatment to one or two ventricles of the patient's heart.

[0108] The second electrode is used to sense the electrical activity of one or both atria of the patient's heart;

[0109] A motion sensor for sensing the mechanical activity of the patient's heart; and

[0110] A controller, operably coupled to the first electrode, the second electrode, and the motion sensor, is configured to:

[0111] Switching between a dual-chamber sensing mode that delivers pacing based on sensing the electrical activity of at least one atrium and at least one ventricle of the patient’s heart and a single-chamber sensing mode that delivers pacing based on sensing the electrical activity of only one or two ventricles of the patient’s heart;

[0112] In the dual-chamber sensing mode, the first electrode is used to deliver pacing to at least one ventricle of the patient's heart;

[0113] Determine whether the electrical activity of one or both atria sensed by the second electrode indicates atrial fibrillation;

[0114] In response to determining that the electrical activity of one or both atria indicates atrial fibrillation, it is determined whether the mechanical activity of the patient's heart sensed by the motion sensor indicates atrial contraction; and

[0115] In response to determining that the mechanical activity of the patient's heart does not indicate atrial contraction, the first electrode is used in the single-chamber sensing mode to deliver suppressed pacing.

[0116] In implementation scheme B2, a system includes the system according to implementation scheme B1, wherein the electrical activity of one or both atria of the patient's heart is based on far-field measurements sensed by the second electrode.

[0117] In embodiment B3, a system includes the system according to embodiment B1, wherein the first electrode and the second electrode are coupled to a leadless implantable medical device (IMD), wherein:

[0118] The shell of the leadless IMD can be implanted into the right atrium (RA) of the patient's heart; and

[0119] The first electrode can be implanted from the Koch triangle of the RA in the patient's heart to deliver cardiac therapy or sense electrical activity of the left ventricle (LV) in the basal region, septal region, or baso-septal region of the left ventricular myocardium of the patient's heart.

[0120] In embodiment B4, a system includes the system according to embodiment B1, wherein the electrical activity of one or both atria of the patient's heart is based on near-field measurements sensed by the second electrode.

[0121] In implementation scheme B5, a system includes the system according to any of the preceding B implementation schemes, wherein, in order to determine whether the electrical activity of one or two atria sensed by the second electrode indicates atrial fibrillation, the controller is further configured to determine whether a P wave is detected.

[0122] In implementation scheme B6, a system includes the system according to implementation scheme B5, wherein, in response to determining the mechanical activity of the patient's heart representing atrial contraction, the controller is further configured to:

[0123] Adjusting the atrial activation threshold to detect the P wave or adjusting the P wave detection latency; and

[0124] Continue to deliver pacing to at least one ventricle of the patient's heart in the dual-chamber sensing mode.

[0125] In implementation scheme B7, a system includes the system according to any of the preceding B implementation schemes, wherein, in response to determining that the electrical activity of one or two atria does not indicate atrial fibrillation, the controller is further configured to continue delivering pacing to at least one ventricle of the patient's heart in the dual-chamber sensing mode.

[0126] In implementation scheme B8, a system includes the system according to any of the preceding B implementation schemes, wherein the mechanical activity of the patient's heart sensed by the motion sensor includes mechanical activity corresponding to the S4 heart sound.

[0127] In implementation scheme B9, a system includes the system according to any of the preceding B implementation schemes, wherein, in order to determine whether the mechanical activity of the patient's heart sensed by the motion sensor indicates atrial contraction, the controller is further configured to detect inherent ventricular activation of the patient's heart.

[0128] In implementation scheme B10, a system includes the system according to implementation scheme B9, wherein, in order to determine whether the mechanical activity of the patient's heart sensed by the motion sensor indicates atrial contraction, the controller is further configured to use the mechanical activity in a time window that begins earlier than the inherent ventricular activation.

[0129] In implementation scheme B11, a system includes the system according to any of the preceding B implementation schemes, wherein, in order to determine whether the mechanical activity of the patient's heart sensed by the motion sensor indicates atrial contraction, the controller is further configured to determine whether the mechanical activity exceeds a threshold.

[0130] In implementation scheme B12, a system includes the system according to implementation scheme B11, wherein the controller is further configured to determine that the mechanical activity represents the atrial contraction in response to the mechanical activity exceeding the threshold.

[0131] In embodiment B13, a system includes the system according to any of the preceding embodiments B, wherein, after delivering suppressed pacing to at least one ventricle of the patient's heart in the single-chamber sensing mode, the controller is further configured to return to delivering pacing to at least one ventricle of the patient's heart in the dual-chamber sensing mode in response to determining that the electrical activity of one or two atria does not indicate atrial fibrillation or determining that the mechanical activity of the patient's heart indicates atrial contraction.

[0132] In implementation scheme B14, a system includes the system according to implementation scheme B13, wherein determining that the electrical activity of one or two atria does not indicate atrial fibrillation includes detecting P waves in the electrical activity of one or two atria, and wherein determining that the mechanical activity of the patient's heart indicates atrial contraction includes determining that the mechanical activity exceeds a threshold.

[0133] In implementation scheme C1, one method includes:

[0134] In a dual-chamber sensing mode, pacing is delivered to at least one ventricle of the patient's heart based on sensing the electrical activity of at least one atrium and at least one ventricle of the patient's heart;

[0135] Determine whether the electrical activity of one or both atria of the patient's heart indicates atrial fibrillation;

[0136] In response to determining whether the electrical activity of one or both atria indicates atrial fibrillation, it is determined whether the mechanical activity of the patient's heart indicates atrial contraction; and

[0137] In response to determining that the mechanical activity of the patient's heart does not indicate atrial contraction, and in a single-chamber sensing mode that delivers pacing based on sensing the electrical activity of only one or two ventricles of the patient's heart, suppressed pacing is delivered to at least one ventricle of the patient's heart.

[0138] In implementation scheme C2, a method includes the method according to implementation scheme C1, wherein the electrical activity of one or both atria of the patient's heart is based on far-field measurements.

[0139] In implementation scheme C3, a method includes the method according to any of the preceding C implementation schemes, wherein determining whether the electrical activity of one or both atria indicates atrial fibrillation includes determining whether a P wave is detected.

[0140] In implementation scheme C4, a method includes the method according to any of the preceding C implementation schemes, wherein the mechanical activity of the patient's heart includes mechanical activity corresponding to the S4 heart sound.

[0141] In embodiment C5, a computer-readable medium includes instructions stored thereon that, when executed, cause a processor to perform the method according to any of the preceding embodiments C.

[0142] In implementation scheme D1, an implantable medical system includes:

[0143] A first medical device, comprising a housing capable of being implanted in at least one ventricle of a patient's heart, further comprising:

[0144] At least one electrode, said at least one electrode being used to sense the electrical activity of at least one ventricle of the patient's heart or to deliver cardiac treatment to at least one ventricle of the patient's heart; and

[0145] At least one motion sensor, said at least one motion sensor being used to sense the mechanical activity of the patient's heart;

[0146] A second medical device, operatively communicating with the first medical device, includes at least one electrode for sensing electrical activity in one or both atria of the patient's heart; and

[0147] The controller is configured to:

[0148] Switching between a dual-chamber sensing mode that delivers pacing based on sensing the electrical activity of at least one atrium and at least one ventricle of the patient’s heart and a single-chamber sensing mode that delivers pacing based on sensing the electrical activity of only one or two ventricles of the patient’s heart;

[0149] In the dual-chamber sensing mode, pacing is delivered to at least one ventricle of the patient's heart;

[0150] Determine whether the electrical activity of one or both atria sensed by the second medical device indicates atrial fibrillation;

[0151] In response to determining that the electrical activity of one or both atria indicates atrial fibrillation, it is determined whether the mechanical activity of the patient's heart sensed by the first medical device indicates atrial contraction; and

[0152] In response to determining that the mechanical activity of the patient's heart does not indicate atrial contraction, suppressed pacing is delivered to at least one ventricle of the patient's heart in the single-chamber sensing mode.

[0153] In implementation D2, a system includes the system according to implementation D1, wherein the first medical device includes the controller.

[0154] In embodiment D3, a system includes the system according to any of the preceding embodiments D, wherein the electrical activity of one or both atria of the patient's heart is based on far-field measurements sensed by the at least one electrode of the second medical device.

[0155] In implementation scheme D4, a system includes the system according to any of the preceding D implementation schemes, wherein the first medical device is an intracardiac implantable medical device.

[0156] In embodiment D5, a system includes the system according to any of the preceding embodiments D, wherein the first medical device is a leadless implantable device positioned in the left ventricle of the patient's heart.

[0157] In embodiment D6, a system includes the system according to any of the preceding embodiments D, wherein the second medical device is a right-side implantable device or an extravascular device.

[0158] In embodiment D7, a system includes the system according to any of the preceding embodiments D, wherein the housing of the first medical device is implantable in the left ventricle (LV) of the patient's heart, and the at least one electrode of the first medical device is implantable to deliver cardiac treatment to the LV or sense the electrical activity of the LV, wherein the second medical device includes a vascular shell.

[0159] In implementation D8, a system includes the system according to any of the preceding D implementations, wherein the second medical device is operatively coupled to transmit the atrial activation time to the first medical device to deliver pacing from the first medical device based on the atrial activation time.

[0160] Therefore, various embodiments of the “CARDIAC RESYNCHRONIZATION THERAPY MODE SWITCHING USING MECHANICAL ACTIVITY” are disclosed. It should be understood that the various aspects disclosed herein can be combined with combinations different from those specifically presented in the specification and figures. It should also be understood that, depending on the example, certain actions or events of any process or method described herein may be performed in a different order, and may be completely added, combined, or omitted (e.g., performing the described technique may not require all the described actions or events). Furthermore, although for clarity some aspects of this disclosure are described as being performed by a single module or unit, it should be understood that the techniques of this disclosure can be performed by combinations of units or modules associated with, for example, a medical device.

[0161] In one or more examples, the described techniques may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, the functionality may be stored as one or more instructions or code on a computer-readable medium and executed by a hardware-based processing unit. Computer-readable media may include non-transitory computer-readable media, which correspond to tangible media such as data storage media (e.g., RAM, ROM, EEPROM, flash memory, or any other medium that can be used to store desired program code in the form of instructions or data structures and is accessible by a computer).

[0162] The instructions can be executed by one or more processors, such as one or more digital signal processors (DSPs), general-purpose microprocessors, application-specific integrated circuits (ASICs), field-programmable arrays (FPGAs), or other equivalent integrated or discrete logic circuits. Therefore, as used herein, the term "processor" can refer to any of the aforementioned structures or any other physical structures suitable for implementing the described technology. Furthermore, this technology can be fully implemented in one or more circuit or logic elements.

[0163] All references and publications cited herein are expressly incorporated in their entirety by way of citation for all purposes, unless in any way directly contradict this disclosure.

[0164] Unless otherwise stated, all scientific and technical terms used herein have their common meaning in the art. The definitions provided herein are intended to facilitate understanding of certain terms frequently used herein and are not intended to limit the scope of this disclosure.

[0165] Unless otherwise specified, all numerical values ​​used in the specification and claims to represent characteristic dimensions, quantities, and physical properties are to be understood as being modified by the terms “precisely” or “about”. Therefore, unless indicated to the contrary, the numerical parameters set forth in the foregoing specification and appended claims are approximate values ​​that may vary within typical ranges of experimental error, depending on the desired properties sought by a person skilled in the art using the teachings disclosed herein.

[0166] The numerical range described by the endpoints includes all values ​​contained within that range (e.g., 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, and 5) and any range within that range. In this document, the terms "at most" or "not greater than" a value (e.g., at most 50) include that value (e.g., 50), and the terms "not less than" a value (e.g., not less than 5) include that value (e.g., 5).

[0167] The term “connection” or “link” refers to components being directly attached to each other (in direct contact with each other) or indirectly attached to each other (having one or more components between and attaching to the two components). Either term may be modified by the interchangeable terms “operationally” and “operably” to describe that the connection or link is configured to allow components to interact to perform a function.

[0168] As used herein, unless otherwise expressly stated in this disclosure, the term “configured as” may be used interchangeably with the terms “suitable” or “structured as”.

[0169] Unless the context clearly specifies otherwise, the singular forms “a,” “an,” and “the” cover implementations with plural indicators.

[0170] 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 or any combination of two or more items in the list.

[0171] As used in this article, "have," "having," "include," "including," "comprise," and "comprising" are used in their open-ended sense and usually mean "including but not limited to." It should be understood that phrases such as "basically composed of" or "composed of" are categorized under "comprising."

[0172] References to “an embodiment,” “an embodiment,” “certain embodiments,” or “some embodiments,” etc., mean that a particular feature, configuration, composition, or characteristic described in connection with that embodiment is included in at least one embodiment of this disclosure. Therefore, the appearance of such shortened terms throughout the document does not necessarily refer to the same embodiment of this disclosure. Furthermore, particular features, configurations, compositions, or characteristics may be combined in any suitable manner in one or more embodiments.

Claims

1. An implantable medical system, the implantable medical system comprising: A first electrode is used to sense the electrical activity of one or two ventricles of a patient's heart or to deliver cardiac treatment to one or two ventricles of the patient's heart. The second electrode is used to sense the electrical activity of one or both atria of the patient's heart; A motion sensor for sensing the mechanical activity of the patient's heart; as well as A controller, operably coupled to the first electrode, the second electrode, and the motion sensor, is configured to: Switching between a dual-chamber sensing mode that delivers pacing based on sensing the electrical activity of at least one atrium and at least one ventricle of the patient’s heart and a single-chamber sensing mode that delivers pacing based on sensing the electrical activity of only one or two ventricles of the patient’s heart; In the dual-chamber sensing mode, the first electrode is used to deliver pacing to at least one ventricle of the patient's heart; Determine whether the electrical activity of one or both atria sensed by the second electrode indicates atrial fibrillation; In response to determining that the electrical activity of one or two atria indicates atrial fibrillation, it is determined whether the mechanical activity of the patient's heart sensed by the motion sensor indicates atrial contraction; as well as In response to determining that the mechanical activity of the patient's heart does not indicate atrial contraction, the first electrode is used in the single-chamber sensing mode to deliver suppressed pacing.

2. The system of claim 1, wherein the electrical activity of one or both atria of the patient's heart is based on far-field measurements sensed by the second electrode.

3. The system according to any one of claims 1-2, wherein the first electrode and the second electrode are coupled to a leadless implantable medical device (IMD), wherein: The housing of the leadless implantable medical device (IMD) is capable of being implanted into the right atrium (RA) of the patient's heart; and The first electrode can be implanted from the Koch triangle of the right atrium (RA) of the patient's heart to deliver cardiac therapy to the basal region, septal region, or baso-septal region of the left ventricular myocardium of the patient's heart or to sense the electrical activity of the left ventricle (LV) in these regions.

4. The system according to any one of claims 1-2, wherein the electrical activity of one or both atria of the patient's heart is based on near-field measurements sensed by the second electrode.

5. The system according to any one of claims 1-2, wherein, in order to determine whether the electrical activity of one or both atria sensed by the second electrode indicates atrial fibrillation, the controller is further configured to determine whether a P wave is detected.

6. The system according to claim 5, wherein, In response to determining that the mechanical activity of the patient's heart represents atrial contraction, the controller is further configured to: Adjust the atrial activation threshold to detect the P wave or adjust the P wave detection latency; and Continue to deliver pacing to at least one ventricle of the patient's heart in the dual-chamber sensing mode.

7. The system according to any one of claims 1-2, wherein, In response to determining that the electrical activity of one or two atria does not indicate atrial fibrillation, the controller is also configured to continue delivering pacing to at least one ventricle of the patient's heart in the dual-chamber sensing mode.

8. The system according to any one of claims 1-2, wherein the mechanical activity of the patient's heart sensed by the motion sensor includes mechanical activity corresponding to the S4 heart sound.

9. The system according to any one of claims 1-2, wherein, in order to determine whether the mechanical activity of the patient's heart sensed by the motion sensor indicates atrial contraction, the controller is further configured to detect intrinsic ventricular activation of the patient's heart.

10. The system of claim 9, wherein, in order to determine whether the mechanical activity of the patient's heart sensed by the motion sensor indicates atrial contraction, the controller is further configured to use the mechanical activity in a time window that begins earlier than the inherent ventricular activation.

11. The system according to any one of claims 1-2, wherein, in order to determine whether the mechanical activity of the patient's heart sensed by the motion sensor indicates atrial contraction, the controller is further configured to determine whether the mechanical activity exceeds a threshold.

12. The system of claim 11, wherein the controller is further configured to determine that the mechanical activity represents the atrial contraction in response to the mechanical activity exceeding the threshold.

13. The system according to any one of claims 1-2, wherein, After delivering suppressed pacing to at least one ventricle of the patient's heart in the single-chamber sensing mode, the controller is further configured to return to delivering pacing to at least one ventricle of the patient's heart in the dual-chamber sensing mode in response to determining that the electrical activity of one or two atria does not indicate atrial fibrillation or determining that the mechanical activity of the patient's heart indicates atrial contraction.

14. The system of claim 13, wherein determining that the electrical activity of one or two atria does not indicate atrial fibrillation includes detecting P waves in the electrical activity of one or two atria, and wherein determining that the mechanical activity of the patient's heart indicates atrial contraction includes determining that the mechanical activity exceeds a threshold.

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