Confirming physiologic parameter sensing in a multi-device implanted system

Abstract

A first device comprises an accelerometer and is configured to deliver cardiac pacing to a patient, and sense physiological activity of the patient sensed via the accelerometer. A second device is configured to sense the physiological activity of the patient via a plurality of electrodes. Processing circuitry is configured to compare the sensing of the physiological activity by the first device to the sensing of the physiological activity by the second device and based on the comparison, control whether the first device delivers the cardiac pacing based on the sensing of the physiological activity via the accelerometer.

Description

CONFIRMING PHYSIOLOGIC PARAMETER SENSING IN A MULTI-DEVICE IMPLANTED SYSTEM

[0001] This application claims the benefit of U.S. Provisional Patent Application Serial No. 63 / 711,366, filed October 24, 2024, the entire content of which is incorporated herein by reference.FIELD

[0002] This disclosure generally relates to medical devices and, more particularly, to medical devices that control therapy based on sensed physiological activity of patients.BACKGROUND

[0003] In healthy humans, heart rate naturally increases during inspiration and decreases during expiration. This phenomenon, known as respiratory sinus arrhythmia (RSA), supports ventilation / perfusion matching as blood enters the lungs, i.e., increases pulmonary blood flow when the lungs are inflated. Some patients lose natural RSA, and delivery of cardiac pacing to mimic natural RSA, referred to as respirophasic pacing, has been proposed for such patients. Delivery of respirophasic pacing may include sensing respiration of a patient and delivering / modifying the cardiac pacing based on the sensed respiration.

[0004] Delivery of respirophasic pacing is one example of controlling delivery of a therapy based on sensed physiological activity of a patient. Delivery of many other cardiac and non-cardiac therapies is controlled based on sensed physiological activity. As one other example, delivery of atrioventricular synchronous ventricular pacing is controlled based on sensing atrial activity, e.g., P-waves or atrial contractions.

[0005] Conventional cardiac pacemakers and implantable cardioverter defibrillators (ICDs) have been implanted subcutaneously or submuscularly, e.g., pectorally, and connected to intracardiac electrodes via one or more transvenous leads. To avoid potential complications associated with transvenous and intracardiac leads, other configurations of these devices have been proposed. For example, leadless cardiac pacemakers configured for implantation within the heart have been proposed. Additionally, ICD systems in whichall electrodes are extravascular or otherwise extracardiac, e.g., subcutaneous or substemal, have been proposed.SUMMARY

[0006] While leadless pacing devices (LPDs) and extracardiac ICDs may provide advantages relative to devices coupled to transvenous and / or intracardiac leads, there may be challenges associated with their ability to provide certain types of cardiac pacing.While extracardiac ICDs can deliver cardiac pacing, the relatively greater distance between their electrodes and cardiac tissue may result in relatively high capture thresholds, and thus relatively greater power source consumption and relatively higher chance of patient discomfort associated with pacing. Ventricular LPDs can deliver pacing with capture thresholds similar to conventional pacemakers, but typically have closely spaced electrodes, and thus may have difficultly electrically sensing P-waves for atrioventricular synchronous pacing and respiration for respirophasic pacing. Such LPDs may be configured to use an accelerometer to sense atrial activity and respiration, but the quality of such sensing may be variable over time and / or between patients and may generally be lower than electrical sensing by conventional pacemakers.

[0007] In general, this disclosure describes techniques for determining whether a device, e.g., an LPD, will deliver cardiac pacing based on its sensing of physiological activity, e.g., via an accelerometer. The physiological activity may be atrial activity for atrioventricular synchronous pacing, or respiration for respirophasic pacing. The determination may be made based on a comparison between the sensing of the physiological activity by the first device and sensing of the physiological activity by a second device, e.g., a co-implanted extracardiac ICD. The sensing of the physiological activity by the first device may be mechanical, e.g., via an accelerometer of the first device. The sensing of the physiological activity by the second device may be electrical, e.g., recording electrogram (EGM) or impedance values via electrodes of the second device. The comparison between the sensing may comprise comparison of the timing of detection of the same events, e.g., P-waves and atrial contractions, or respiration phases, by the two devices. The devices may communicate, e.g., wirelessly, with each other and / or another computing device or computing system regarding their clocks and their sensing of physiological activity, e.g., event timings, to facilitate the comparison.

[0008] While the second device may be better able to sense the physiological activity than the first device, the first device may be better able to deliver the cardiac pacing. Wireless communication between the first and second device so that the second device could sense the physiological activity and trigger delivery of the pacing, e.g., respirophasic pacing, would consume significant energy of both devices. The techniques of this disclosure advantageously coordinate the activity of a multiple device system to facilitate therapeutic and energy effective pacing and sensing by the first device so long as its sensing satisfies one or more criteria, while also providing backup therapy options if needed.

[0009] In one example, this disclosure describes a system which includes a first device. The first device may include an accelerometer and may be configured to deliver cardiac pacing to a patient; and sense physiological activity of the patient sensed via the accelerometer. A second device may be configured to sense the physiological activity of the patient via a plurality of electrodes. Processing circuitry may be configured to compare the sensing of the physiological activity by the first device to the sensing of the physiological activity by the second device. Based on the comparison, the processing circuitry may be able to control whether the first device delivers the cardiac pacing based on the sensing of the physiological activity via the accelerometer.

[0010] In another example, this disclosure describes a method which includes comparing sensing of physiological activity of a patient by a first device via an accelerometer to sensing of the physiological activity by a second device via a plurality of electrodes. The first device may be configured to deliver cardiac pacing. The method further includes controlling, based on the comparison, whether the first device delivers the cardiac pacing based on the sensing of the physiological activity via the accelerometer.

[0011] In another example, this disclosure describes a non-transitory computer-readable medium storing instructions that when executed cause processing circuitry to: compare sensing of physiological activity of a patient by a first device via an accelerometer to sensing of the physiological activity by a second device via a plurality of electrodes, wherein the first device is configured to deliver cardiac pacing. The processing circuitry may further be caused to, based on the comparison, control whether the first device delivers the cardiac pacing based on the sensing of the physiological activity via the accelerometer.

[0012] In another example, this disclosure describes a system includes a first device configured to deliver respirophasic pacing to a patient; a second device configured to sense respiration of the patient; and processing circuitry configured to control the delivery of the respirophasic pacing by the first device based on the sensing of respiration by the second device.

[0013] In another example, this disclosure describes a method includes delivering respirophasic pacing to a patient by a first device; and controlling the delivery of the respirophasic pacing by the first device based on the sensing of respiration by a second device.

[0014] This summary is intended to provide an overview of the subject matter described in this disclosure. It is not intended to provide an exclusive or exhaustive explanation of the apparatus and methods described in detail within the accompanying drawings and description below. Further details of one or more examples are set forth in the accompanying drawings and the description below.BRIEF DESCRIPTION OF DRAWINGS

[0015] FIGS. 1 A, IB, and 1C are front-view, side-view, and top-view conceptual drawings, respectively, illustrating an example medical device system in conjunction with a patient, in accordance with one or more techniques of this disclosure.

[0016] FIG. 2 is a functional block diagram illustrating an example configuration of the implantable cardioverter defibrillator of FIGS. 1A, IB, and 1C.

[0017] FIG. 3 is a functional block diagram illustrating an example configuration of the pacing device of FIGS. 1A, IB, and 1C.

[0018] FIG. 4 is a functional block diagram illustrating an example configuration of the external device of FIGS. 1A, IB, and 1C.

[0019] FIG. 5 is a block diagram illustrating an example system that includes a server and one or more computing devices that are communicatively coupled to the system of FIGS. 1A, IB, and 1C.

[0020] FIG. 6 is a flowchart illustrating an example technique for controlling whether a device delivers cardiac pacing based on its sensing of physiological activity.

[0021] FIG. 7 is a flowchart illustrating an example technique for determining whether a device delivers atrioventricular synchronous ventricular pacing based on its sensing of atrial activity using an accelerometer.

[0022] FIG. 8 is a flowchart illustrating an example technique for determining whether a device delivers respirophasic pacing based on its sensing of respiration using an accelerometer.

[0023] Like reference characters refer to like elements throughout the figures and description.DETAILED DESCRIPTION

[0024] FIGS. 1 A, IB, and 1C are front-view, side-view, and top-view conceptual drawings, respectively, illustrating an example medical device system 8 in conjunction with a patient 14, in accordance with one or more techniques of this disclosure. Medical device system 8 is an example of a medical device system configured to implement the techniques described herein for controlling whether a device delivers cardiac pacing based on its sensing of physiological activity.

[0025] In the illustrated example, medical device system 8 includes an extracardiac ICD system 100 implanted within patient 14. ICD system 100 includes an ICD 10 connected to at least one extracardiac, e.g. extravascular, implantable lead 102. ICD 10 is configured to deliver high-energy cardioversion or defibrillation pulses to heart 16 of patient 14 when atrial or ventricular fibrillation is detected. Cardioversion shocks are delivered in synchrony with a detected R-wave when sustained ventricular tachycardia criteria are met. Defibrillation shocks are delivered when sustained ventricular fibrillation criteria are met.

[0026] ICD 10 is implanted subcutaneously or submuscularly on the left side of patient 14 above the ribcage. Defibrillation lead 102 may be implanted at least partially in a substernal location, e.g., between the ribcage and / or sternum 110 and heart 16. In one such configuration, a proximal portion of lead 102 extends subcutaneously from ICD 10 toward sternum 110 and a distal portion of lead 102 extends superior under or below the sternum 110 in the anterior mediastinum 112 (FIG. 1C). The anterior mediastinum 112 is bounded laterally by the pleurae 116 (FIG. 1C), posteriorly by the pericardium 114 (FIG.1C), and anteriorly by the sternum 110. In some instances, the anterior wall of the anterior mediastinum may also be formed by the transversus thoracis and one or more costal cartilages. The anterior mediastinum includes a quantity of loose connective tissue (suchas areolar tissue), some lymph vessels, lymph glands, substemal musculature (e.g., transverse thoracic muscle), branches of the internal thoracic artery, and the internal thoracic vein. In one example, the distal portion of lead 102 extends along the posterior side of the sternum 110 substantially within the loose connective tissue and / or substemal musculature of the anterior mediastinum. Lead 102 may be at least partially implanted in other intrathoracic locations, e.g., other non-vascular, extra-pericardial locations, including the gap, tissue, or other anatomical features around the perimeter of and adjacent to, but not attached to, the pericardium or other portion of the heart and not above the sternum 110 or ribcage. Lead 102 may be at least partially implanted within extracardiac, thoracic vasculature.

[0027] In other examples, lead 102 may be implanted at other extracardiovascular locations. For example, lead 102 may extend subcutaneously above the ribcage from ICD 10 toward a center of the torso of patient 14, bend or turn near the center of the torso, and extend subcutaneously superior above the ribcage and / or sternum 110. Lead 102 may be offset laterally to the left or the right of the sternum 110 or located over the sternum 110. Lead 102A may extend substantially parallel to the sternum 110 or be angled lateral from the sternum 110 at either the proximal or distal end.

[0028] Lead 102 includes an insulative lead body having a proximal end that includes a connector 104 configured to be connected to ICD 10 and a distal portion that includes one or more electrodes. Lead 102 also includes one or more conductors that form an electrically conductive path within the lead body and interconnect the electrical connector and respective ones of the electrodes.

[0029] Lead 102 includes a defibrillation electrode that includes two sections or segments 106A and 106B, collectively (or alternatively) defibrillation electrode 106. The defibrillation electrode 106 is toward the distal portion of lead 102, e.g., toward the portion of lead 102 extending along the sternum 110. Lead 102 is placed below and / or along sternum 110 such that a therapy vector between defibrillation electrodes 106 A or 106B and a housing electrode formed by or on ICD 10 (or other second electrode of the therapy vector) is substantially across a ventricle of heart 16. The therapy vector may, in one example, be viewed as a line that extends from a point on defibrillation electrode 106 (e.g., a center of one of the defibrillation electrode sections 106 A or 106B) to a point onthe housing electrode of ICD 10. Defibrillation electrode 106 may, in one example, be an elongated coil electrode.

[0030] Lead 102 may also include one or more pace / sense electrodes, such as electrodes 108 A and 108B (individually or collectively, “electrode(s) 108”), located along the distal portion of defibrillation lead 102. In the example illustrated in FIG. 1 A and FIG. IB, electrodes 108 A and 108B are separated from one another by defibrillation electrode 106A. In other examples, however, electrodes 108 A and 108B may be both distal of defibrillation electrode 106 or both proximal of defibrillation electrode 106. In other examples, lead 102 may include more or fewer electrodes at various locations proximal and / or distal to defibrillation electrode 106. In the same or different examples, ICD 10 may be coupled to one or more electrodes on another lead (not shown).

[0031] ICD system 100 may sense electrical signals via one or more sensing vectors that include combinations of electrodes 108 A and 108B and a housing electrode of ICD 10. In some instances, ICD 10 may sense cardiac electrical signals using a sensing vector that includes one of the defibrillation electrode sections 106 A and 106B and one of sensing electrodes 108 A and 108B or the housing electrode of ICD 10. The sensed electrical intrinsic signals may include electrical signals generated by cardiac muscle and indicative of depolarizations and repolarizations of heart 16 at various times during the cardiac cycle. ICD 10 analyzes the electrical signals sensed by the one or more sensing vectors to detect cardiac depolarizations, and thereby detect arrhythmia, such as ventricular tachycardia or ventricular fibrillation (referred to collectively as ventricular tachyarrhythmias). In response to detecting the tachyarrhythmia, ICD 10 may begin to charge a storage element, such as a bank of one or more capacitors, and, when charged, deliver one or more defibrillation pulses via defibrillation electrode 106 of lead 102 if the tachyarrhythmia is still present.

[0032] In some examples, ICD 10 may be configured to deliver cardiac pacing, e.g., to the ventricles of heart 16, via a combination of electrodes 108 A and 108B, electrode segments 106A and 106B, and / or the housing electrode of ICD 10. ICD may deliver bradycardia pacing, cardiac resynchronization therapy, antitachyarrhythmia pacing, or post shock pacing. In some examples, ICD 10 may be configured to deliver respirophasic pacing.

[0033] Medical device system 8 also includes a leadless pacing device (LPD) 12, which is implanted within heart 16 and configured to deliver cardiac pacing to the heart. In the illustrated example, LPD 12 is implanted within the right ventricle of heart 16. However, in other examples, system 8 may additionally or alternatively include one or more LPDs 12 within other chambers of heart 16, or similarly configured pacing devices attached to an external surface of heart 16 (e.g., in contact with the epicardium) such that the pacing device is disposed outside of heart 16. Further, although generally leadless, some LPDs may include a leadlet or extension to position an electrode a distance from the LPD housing.

[0034] LPD 12 is configured to sense electrical activity of heart 16 and deliver pacing therapy, e.g., bradycardia pacing therapy, cardiac resynchronization therapy (CRT), antitachycardia pacing (ATP) therapy, post-shock pacing, rate adaptive pacing, and / or respirophasic pacing to heart 16. In some examples, the ventricular pacing may be atrioventricular synchronous, in which the timing of the ventricular pacing is timed from an atrial activation event. LPD 12 may be capable of sensing electrical signals using the electrodes carried on the housing of LPD 12. These electrical signals may be electrical signals generated by cardiac muscle and indicative of depolarizations and repolarizations of heart 16 at various times during the cardiac cycle. LPD 12 may detect mechanical activity of patient 14 and / or heart 16 via an accelerometer on or within LPD 12. LPD 12 may additionally or alternatively detect mechanical activity of patient 14 and / or heart 16 via a pressure sensor on or within LPD 12. LPD 12 may be attached to an interior wall of heart 16 via one or more fixation elements that penetrate the tissue. These fixation elements may secure LPD 12 to the cardiac tissue and retain an electrode (e.g., a cathode or an anode) in contact with the cardiac tissue.

[0035] In general, respirophasic pacing includes detecting respiration of patient 14, including inspiration and expiration phases of respiratory cycles, and modifying the cardiac pacing rate during the respiratory cycle, e.g., increasing pacing rate during the inspiration phase and decreasing the pacing rate during the expiration phase. Each of ICD 10 and LPD 12 may be configured to detect respiration, e.g., respiratory cycles and phases thereof, and / or control a cardiac pacing rate to provide respirophasic pacing. ICD 10 may be configured to detect respiration based on changes in impedance, e.g., measured via one or more of electrodes 106 or 108 in combination with the housing electrode of ICD 10.LPD 12 may be configured to detect respiration via an accelerometer of LPD 12. ICD 10 and / or LPD 12 may be configured to detect respiration based on a baseline shift of the EGM, e.g., measured shifts in the EGM via one or more of electrodes 106 or 108 in combination with the housing electrode of ICD 10. ICD 10 and / or LPD 12 may be configured to detect respiration based on one or more optical sensors, e.g., one or more optical sensors may detect localized changes to light absorption and reflection based on breathing cycles. ICD 10 and / or LPD 12 may be configured to detect respiration based on R-Wave peak variation, e.g., one or more R-Wave detection methods may detect a downward shift in R-wave amplitude during an inhalation and an upwards shift in R-Wave amplitude during an exhalation due to respiratory sinus arrythmia. With respect to the techniques of this disclosure, LPD 12 may be a first device configured to deliver cardiac pacing, and ICD 10 may be considered a second device, where both the first and second devices are configured to sense physiological activity but may do so via different sensor modalities.

[0036] ICD 10 and LPD 12 may be configured to wirelessly communicate with each other, e.g., in order to coordinate their sensing and therapy delivery activities and / or implement the techniques of this disclosure. One or both of ICD 10 and LPD 12 may also be configured to wirelessly communicate with external device 30. External device 30 may be a computing device that may be used in a home, ambulatory setting, clinic, or hospital setting, to communicate with one or both devices via wireless telemetry. External device 30A may be coupled to a remote patient monitoring system, such as Carelink®, available from Medtronic, Inc, of Minneapolis, Minnesota. External device 30 may be, as examples, a programmer, external monitor, or consumer device, e.g., smart phone.

[0037] External device 30 may be used to program commands or operating parameters into one or both devices for controlling its functioning, e.g., when configured as a programmer. External device 30 may be used to interrogate ICD 10 and / or LPD 12 to retrieve data, including device operational data as well as physiological data accumulated in IMD memory. The interrogation may be automatic, e.g., according to a schedule, or in response to a remote or local user command. Examples of communication techniques used by the IMDs and external device 30 may include radiofrequency (RF) telemetry, which may be an RF link established via Bluetooth®, WiFi, acoustic, optical, tissue conductance communication (TCC) or medical implant communication service (MICS). Insome examples, communication techniques used by the IMDs and external device 30 may include one device of the IMDs and external device 30 delivering a subthreshold pacing pulse which may be picked up by a second device of the IMDs and external device 30, whereby two or more subthreshold pacing pulse may communicate information.

[0038] Although FIGS. 1 A - 1C are shown or described in the context of LPD 12 as the first device and ICD 10 as the second device, techniques in accordance with one or more aspects of the present disclosure may be applicable to other coexistent systems. For example, the first device and / or second device may be coupled to transvenous leads, or the second device may be any implantable device configured to sense, e.g., electrically, atrial activity and / or respiration, such as an insertable cardiac monitor or a neurostimulator. Furthermore, one or both of the first and second device need not be implantable, and the second device may be a consumer device rather than a dedicated medical device. As such, the example of FIGS. 1 A - 1C is illustrated for example purposes only and should not be considered limiting of the techniques described herein.

[0039] FIG. 2 is a functional block diagram illustrating an example configuration of ICD 10 in accordance with one or more techniques of this disclosure. In the illustrated example, ICD 10 includes switch circuitry 202 that may selectively couple sensing circuitry 204 and therapy delivery circuitry 206 to combinations of electrodes 208 as controlled by processing circuitry 210. Electrodes 208 may correspond to electrodes 106 and 108, and a housing electrode, as described with respect to FIGS. 1A - 1C. Switch circuitry 202 may include a switch array, switch matrix, multiplexer, or any other type of switching device suitable to selectively couple circuitry to selected electrodes. ICD 10 may also include one or more sensors 209, communication circuitry 212, and memory 214. Memory 214 includes computer-readable instructions that, when executed by processing circuitry 210, cause ICD 10 and processing circuitry 210 to perform various functions attributed to ICD 10 and processing circuitry 210 herein. Memory 214 may include any volatile, non-volatile, magnetic, optical, or electrical media, such as a random access memory (RAM), read-only memory (ROM), non-volatile RAM (NVRAM), electrically-erasable programmable ROM (EEPROM), flash memory, or any other digital or analog media.

[0040] Processing circuitry 210 may include any one or more of a microprocessor, a controller, a digital signal processor (DSP), a tensor signal processor (TSP) an applicationspecific integrated circuit (ASIC), a field-programmable gate array (FPGA), a neural processing unit (NPU), graphical processing unit (GPU), or equivalent discrete or analog logic circuitry. In some examples, processing circuitry 210 may include multiple components, such as any combination of one or more microprocessors, one or more controllers, one or more DSPs, one or more TSPs, one or more ASICs, or one or more FPGAs, as well as other discrete or integrated logic circuitry. The functions attributed to processing circuitry 210 herein may be embodied as software, firmware, hardware or any combination thereof, e.g., may be embodied as software or firmware executed on processing circuitry.

[0041] Processing circuitry 210 controls therapy delivery circuitry 206 to deliver therapy to heart 16, e.g., cardiac pacing and / or antitachyarrhythmia shocks, via electrodes 208 according to therapy parameters and programs which may be stored in memory 214. Therapy delivery circuitry 206 includes circuitry, such as charge pumps, capacitors, current mirrors, or other signal generation circuitry for generating a pulse or other signal.

[0042] Sensing circuitry 204 monitors signals from electrodes 208 in order to monitor cardiac EGM signals of heart 16 and / or other patient parameters. Sensing may be done to detect intrinsic cardiac depolarizations, e.g., ventricular depolarizations (R- waves) and atrial depolarizations (P -waves), to detect arrhythmias, to determine heart rates or heart rate variability, or to detect other electrical signals. Memory 214 may store the cardiac EGM signals and / or indications of the timing of detected events, e.g., depolarizations and arrhythmias. Sensing circuitry 204 may include one or more filters, amplifiers, analog-to-digital converters, or other sensing circuitry. In some examples, sensing circuitry 204 may measure impedance, e.g., to sense respiration, and may include voltage or current generation circuitry and circuitry for sampling measuring the other of current or voltage to determine the impedance.

[0043] Switch circuitry 202 may selectively couple sensing circuitry 204 to a combination of electrodes 208 depending upon which electrode combination, or electrode vector, is used in the current sensing or measurement configuration. In some examples, processing circuitry 210 may select the electrodes that function as sense electrodes, i.e., select the sensing configuration, via the switch circuitry. Sensing circuitry 204 may include one or more detection channels, each of which may be coupled to a selected electrode configuration for detection of cardiac signals via that electrode configuration.Some detection channels may be configured to detect cardiac events, such as P- or R-waves, and provide indications of the occurrences of such events to processing circuitry 210.

[0044] One or more sensor(s) 309 may include, as examples, one or more accelerometers, microphones, temperature sensors, or optical sensors that are configured to provide signals or data representing one or more patient parameters to processing circuitry 210. In some examples, processing circuitry 210 may determine a patient state, e.g., whether patient 14 is experiencing arrhythmia, heart failure, or some other disease state, based on signals sensed via one or more sensor(s) 209 in addition to or instead of the cardiac EGM signal.

[0045] Processing circuitry 210 may implement programmable counters that control the basic time intervals associated with VDD, VVI, and other modes of pacing. Intervals defined by processing circuitry 210 may include atrial and ventricular pacing escape intervals, A-V intervals, refractory periods during which sensed P-waves and R-waves are ineffective to restart timing of the intervals. The durations of these intervals may be determined by processing circuitry 210 in response to stored data in memory 214.

[0046] Memory 214 may also store data usable by processing circuitry 210 to control therapy delivery circuitry 206 to deliver respirophasic pacing. The data may define pacing rate increases and decreases, e.g., ramped or stepped, during the inhalation and expiration phases of the cardiac cycle. The rate changes may be defined as absolute or percentage changes relative to the current base pacing rate, which may be a sensor indicated rate for rate responsive pacing.

[0047] Interval counters implemented by processing circuitry 210 may be reset upon sensing of R-waves and P-waves with detection channels of sensing circuitry 204 and / or delivery of pacing pulses. The value of the count present in the interval counters when reset by sensed R-waves and P-waves may be used by processing circuitry 210 to measure the durations of R-R intervals, P-P intervals, P-R intervals and R-P intervals, which are measurements that may be stored in memory 214. Processing circuitry 210 may use the count in the interval counters to detect a tachyarrhythmia event, such as atrial fibrillation (AF), atrial tachycardia (AT), ventricular fibrillation (VF), or ventricular tachycardia (VT).

[0048] Communication circuitry 212 includes any suitable hardware, firmware, software or any combination thereof for communicating with another device, such as LPD 12 and / or external device 30 (FIGS. 1A - 1C). Under the control of processing circuitry 210, communication circuitry 212 may communicate with the aid of an antenna, which may be internal and / or external, according to any of the wireless protocols discussed above.

[0049] FIG. 3 is a functional block diagram illustrating an example configuration of LPD 12. LPD 12 may include switch circuitry 302, sensing circuitry 304, therapy delivery circuitry 306, electrodes 308, sensor(s) 309, processing circuitry 310, communication circuitry 312, and memory 314. The components of LPD 12 may be configured in a substantially similar manner to the like numbered and named components of ICD 10, with some differences noted herein.

[0050] For example, therapy delivery circuitry 306 may not be configured to deliver antitachyarrhythmia shocks. Furthermore, due to the location of electrodes 308 within a ventricle of heart 16, sensing circuitry 304 may not be configured to sense P-waves.

[0051] Additionally, as illustrated in FIG. 3, sensor(s) 309 may include one or more accelerometers 311. In some examples, processing circuitry 310 may analyze the one or more signals from accelerometer(s) 311 to identify atrial activity, e.g., atrial contractions corresponding to P-waves. Processing circuitry 310 may control delivery of atrioventricular synchronous ventricular pacing based on the detected atrial activity, e.g., an A-V interval after detection of the activity. In some examples, processing circuitry 310 may analyze the one or more signals from accelerometer(s) 311 to identify respiration, e.g., including respiratory cycles and phases of respiratory cycles. Processing circuitry 310 may control delivery of respirophasic pacing based on the detected respiration, e.g., increase and decrease pacing rate as discussed above.

[0052] FIG. 4 is a block diagram illustrating an example configuration of an external device 30 that operates in accordance with one or more techniques of this disclosure. External device 30 is configured to communicate one or both of ICD 10 and LPD 12. In the example of FIG. 4, external device 30 includes processing circuitry 410, communication circuitry 412, user interface 404, and memory 414.

[0053] Processing circuitry 410, in one example, may include one or more processors that are configured to implement functionality and / or process instructions for executionwithin external device 30. For example, processing circuitry 410 may be capable of processing instructions stored in memory 414. Processing circuitry 410 may include, for example, microprocessors, DSPs, ASICs, FPGAs, GPUs, TPUs, or equivalent discrete or integrated logic circuitry, or a combination of any of the foregoing devices or circuitry. Accordingly, processing circuitry 410 may include any suitable structure, whether in hardware, software, firmware, or any combination thereof, to perform the functions ascribed herein to processing circuitry 410.

[0054] A user, such as a clinician or patient 14, may interact with external device 30 through user interface 404. User interface 404 includes a display (not shown), such as an LCD or LED display or other type of screen, with which processing circuitry 410 may present information related to an IMD, e.g., current programmed parameters, programming options, and indications of detected parameters, events, or episodes of patient 14, some or all of which may be received from the IMD. In addition, user interface 404 may include an input mechanism to receive input from the user. The input mechanisms may include, for example, any one or more of buttons, a keypad (e.g., an alphanumeric keypad), a peripheral pointing device, a touch screen, or another input mechanism that allows the user to navigate through user interfaces presented by processing circuitry 410 of external device 30 and provide input, e.g., make programming or review selections. In other examples, user interface 404 also includes audio circuitry for providing audible notifications, instructions or other sounds to the user, receiving voice commands from the user, or both.

[0055] Communication circuitry 412 may include any suitable hardware, firmware, software or any combination thereof for communicating with another device, such as ICD 10 and / or LPD 12. Memory 414 may be configured to store information within external device 30 during operation. In some examples, memory 414 may be referred to as a storage device and include computer-readable instructions that, when executed by processing circuitry 410, cause external device 30 and processing circuitry 410 to perform various functions attributed to external device 30 and processing circuitry 410 herein. Memory 414 may include any volatile, non-volatile, magnetic, optical, or electrical media, such as RAM, DRAM, SRAM, magnetic discs, optical discs, flash memories, ROM, NVRAM, EPROM, EEPROM, flash memory, or any other digital media. Memory 414 may also store data generated by ICD 10 and / or LPD 12, such as atrial activity orrespiration signals, and / or data corresponding to timing of detections of atrial activity and respiration cycles or phases. In some examples, processing circuitry that performs the example techniques described herein for controlling whether LPD 12 delivers cardiac pacing based on its sensing, e.g., using accelerometer 311, may include processing circuitry 410 of external device 30.

[0056] FIG. 5 is a block diagram illustrating an example system 500 that includes an access point 501, a network 502, external computing devices, such as server 504, and one or more other computing devices 510A-510N (collectively, “computing devices 510”), which may be coupled to ICD 10 and / or LPD 12, referred to as IMDs 10,12, and external device 30 via network 502, in accordance with one or more techniques described herein. IMDs 10,12 may also communicate with network 502 via access point 501, which may be a device that connects to network 502 via any of a variety of connections, such as telephone dial-up, digital subscriber line (DSL), or cable modem connections. In some examples, access point 501 may be a user device, such as a tablet or smartphone, or a device dedicated to allowing IMDs to access network 502, that may be co-located with the patient. As discussed above, IMDs 10,12 may be configured to transmit data to external device 30. In addition, access point 501 may interrogate HMDs 10,12, such as periodically or in response to a command from the patient or network 502, in order to retrieve patient data from the IMDs.

[0057] In some cases, server 504 may be configured to provide a secure storage site for data that has been collected from IMDs 10,12, and / or external device 30. In some cases, server 504 may assemble data for viewing by clinicians via computing devices 510. One or more aspects of the illustrated system of FIG. 5 may be implemented with general network technology and functionality, which may be similar to that provided by the Medtronic CareLink™ Network developed by Medtronic, Inc.

[0058] Server 504 may include processing circuitry 508 and memory 506. Processing circuitry 508 may include fixed function circuitry and / or programmable processing circuitry and may include any one or more of a microprocessor, a controller, DSP, GPU, TSP, ASIC, FPGA, or equivalent discrete or analog logic circuitry. In some examples, processing circuitry 508 may include multiple components, such as any combination of one or more microprocessors, one or more controllers, one or more DSPs, one or more ASICs, or one or more FGPAs, one or more GPUs, one or more TPUs, as well as otherdiscrete of integrated logic circuitry. The functions attributed to processing circuitry of server 508 may be embodied as software, firmware, hardware, or any combination thereof.

[0059] Memory 506 includes computer-readable instructions that, when executed by processing circuitry 508, cause server 504 and processing circuitry 508 to perform various functions attributed to them herein. The memory 506 may include any volatile, nonvolatile, magnetic, optical, or electrical media, such as random access memory (RAM), read only memory (ROM), non-volatile RAM (NVRAM), electronically erasable programmable ROM (EEPROM), flash memory, or any other digital media. Memory 506 may provide storage for data retrieved from ICD 10 and / or LPD 12, such as atrial activity or respiration signals, and / or data corresponding to timing of detections of atrial activity and respiration cycles or phases. In some examples, processing circuitry that performs the example techniques described herein for controlling whether LPD 12 delivers cardiac pacing based on its sensing, e.g., using accelerometer 311, may include processing circuitry 508 of server 504.

[0060] FIG. 6 is a flowchart illustrating an example technique for controlling whether a device, e.g., LPD 12, delivers cardiac pacing based on its sensing of physiological activity, e.g., via accelerometer 311. The example technique illustrated in FIG. 6 may be performed by processing circuitry of system 500, such as any one or more of processing circuitry 210 of ICD 10, processing circuitry 310 of LPD 12, processing circuitry 410 of external device 30, or processing circuitry 508 of server 504. The various devices of system 500 may communicate, e.g., wirelessly, such as physiological signals and / or timing of detections of events, to facilitate the techniques of this disclosure.

[0061] According to the example of FIG. 6, processing circuitry compares sensing of physiological activity by first and second devices (600). For example, processing circuitry may compare sensing of physiological activity by LPD 12 via accelerometer 311 to sensing of the same or corresponding physiological activity by ICD 10 via electrodes 208. The physiological activity may include atrial activity or respiration, as described herein. The comparison may include comparing timing of detection of events, such as P-waves to atrial contractions, or respiratory cycles or phases. The comparison may include comparing timing of any fiducial markers between signals sensed respectively by the first and second devices over the same time periods.

[0062] Based on the comparison, the processing circuitry controls whether the first device delivers cardiac pacing based on its sensing of the physiological activity, e.g., whether LPD 12 paces based on its sensing via accelerometer 311 (602). If processing circuitry of another device, e.g., the second device or a computing device, makes the determination based on the comparison, the other device may control the first device by transmitting a message to the first device.

[0063] FIG. 7 is a flowchart illustrating an example technique for determining whether a device, e.g., LPD 12, delivers atrioventricular synchronous ventricular pacing based on its sensing of atrial activity using an accelerometer, e.g., accelerometer 311. The example technique illustrated in FIG. 7 may be performed by processing circuitry of system 500, such as any one or more of processing circuitry 210 of ICD 10, processing circuitry 310 of LPD 12, processing circuitry 410 of external device 30, or processing circuitry 508 of server 504. The various devices of system 500 may communicate, e.g., wirelessly, such as physiological signals and / or timing of detections of events, to facilitate the techniques of this disclosure.

[0064] According to the example of FIG. 7, processing circuitry collects a timing history of atrial activity sensed by first and second devices, e.g., atrial contractions and P-waves respectively sensed by LPD 12 and ICD 10 (700). The processing circuitry compares the timing histories between the devices (702), and determines whether the comparison satisfies one or more criteria (704). Comparison may include determining a cumulative, mean, or median difference between event detections or other fiducials in the sensing by the first and second devices, determining other metrics of correlation between signals, e.g., cross correlation, or evaluating whether one signal has more noise.

[0065] A first one or more criteria may require closer agreement between the sensing by the different devices than a second one or more criteria. The first and second criteria may include different thresholds for one or more of the metrics of comparison discussed above. If the comparison satisfies the first one or more criteria (FIRST), the first device may deliver atrioventricular synchronous (VDD) pacing based on its sensing of atrial activity using its accelerometer, e.g., LPD 12 delivers VDD pacing using accelerometer 311 (706). FIRST may additionally or alternatively include a determination of whether the second device is inaccurately detecting cardiac activity, and default to the first device delivering the VDD pacing. If the comparison does not satisfy the more stringent firstcriteria, but satisfies the second one or more criteria (SECOND), the first device may deliver VDD pacing based on its sensing of atrial activity using its accelerometer with an offset, e.g., apply an offset to the A-V interval (708). If the comparison does not satisfy either the first or the second criteria (NO), the first device may deliver ventricular pacing that is not atrioventricular synchronous, e.g., VVI pacing (710). In some examples, if the comparison does not satisfy either the first or the second criteria (NO), the second device may provide trigger signals, based on its sensing of atrial activity, to the first device so that the first device may deliver atrioventricular synchronous pacing. In some examples, if the comparison does not satisfy either the first or the second criteria (NO), the second device may deliver atrioventricular synchronous pacing, e.g., ICD 10 delivers VDD pacing via electrodes 106A / 106B.

[0066] In some examples, the system may modify or not use the criteria based on heart rate. For example, the detection of atrial contractions by the first device may be considered less reliable above a threshold heart rate, e.g., 100 beats per minute.Consequently, the processing circuitry of the system may change the criteria above the heart rate threshold to favor (or require) use the second device to sense atrial activity. Additionally, or alternatively, for all physiological sensing examples (e.g., both atrial activity and respiration) a healthcare provider may, via any user interface such as user interface 404, disable one or more criteria based on specific attributes of the patient.

[0067] FIG. 8 is a flowchart illustrating an example technique for determining whether a device, e.g., LPD 12, delivers respirophasic pacing based on its sensing of respiration using an accelerometer, e.g., accelerometer 311. The example technique illustrated in FIG. 8 may be performed by processing circuitry of system 500, such as any one or more of processing circuitry 210 of ICD 10, processing circuitry 310 of LPD 12, processing circuitry 410 of external device 30, or processing circuitry 508 of server 504. The various devices of system 500 may communicate, e.g., wirelessly, such as physiological signals and / or timing of detections of events, to facilitate the techniques of this disclosure.

[0068] According to the example of FIG. 8, processing circuitry collects a timing history of respiration (cycles and / or phases) sensed by first and second devices, e.g., LPD 12 and ICD 10 (800). The processing circuitry compares the timing histories between the devices (802), and determines whether the comparison satisfies one or more criteria (804). Comparison may include determining a cumulative, mean, or median difference betweenevent detections or other fiducials in the sensing by the first and second devices, determining one or more other metrics of correlation between signals, e.g., cross correlation, or determining a noise level of the data recorded from one or both of devices. Each of the one or more metrics may additionally or alternatively be weighted, such that certain factors may entirely outweigh the other factors. In some examples, the weighting may be predetermined by a healthcare provider or come as a default with the device. In other examples, the weighting may be actively updated by ICD 10 and / or LPD 12. The weighting may be updated based on prior success in predicting or any other factor which could influence the accuracy of the weighting.

[0069] A first one or more criteria may require closer agreement between the sensing by the different devices than a second one or more criteria. The first and second criteria may include different thresholds one or more of the metrics of comparison discussed above. If the comparison satisfies the first one or more criteria (FIRST), the first device may deliver respirophasic pacing based on its sensing of atrial activity using its accelerometer, e.g., LPD 12 delivers respirophasic pacing using accelerometer 311 (806). If the comparison does not satisfy the more stringent first criteria, but satisfies the second one or more criteria (SECOND), the first device may deliver respirophasic pacing based on its sensing of atrial activity using its accelerometer with an offset, e.g., apply an offset to the detection of phases before increasing / decreasing the pacing rates (808). If the comparison does not satisfy either the first or the second criteria (NO), the first device may not deliver respirophasic pacing (which may or may not be delivered by the second device (e.g., ICD 10)), or deliver respirophasic pacing where the second device detects the respiration phases and communicates with the first device to trigger the cardiac pacing rate changes (810).

[0070] Example 1 : A system includes a first device which includes an accelerometer, the first medical device configured to deliver cardiac pacing to a patient; and sense physiological activity of the patient sensed via the accelerometer. The system may include a second device configured to sense the physiological activity of the patient via a plurality of electrodes. The system may include processing circuitry configured to compare the sensing of the physiological activity by the first device to the sensing of the physiological activity by the second device and based on the comparison, control whether the firstdevice delivers the cardiac pacing based on the sensing of the physiological activity via the accelerometer.

[0071] Example 2: The system of example 1, wherein the physiological activity comprises respiration, and the cardiac pacing comprises respirophasic pacing.

[0072] Example 3: The system of example 2, wherein the processing circuitry is configured to: based on the comparison satisfying one or more first criteria, control the first device to deliver phases of the respirophasic pacing timed to phases of respiration cycles sensed via the accelerometer; and based on the comparison satisfying one or more second criteria, control the first device to deliver phases of the respirophasic pacing offset relative to phases of respiration cycles sensed via the accelerometer.

[0073] Example 4: The system of example 3, wherein the processing circuitry is configured to, based on the comparison not satisfying the one or more first criteria or the one or more second criteria, control the first device to deliver phases of the respirophasic pacing triggered by one or more commands from the second device.

[0074] Example 5: The system of any of examples 3 and 4, wherein the second device is configured to deliver cardiac pacing, and the processing circuitry is configured to, based on the comparison not satisfying the one or more first criteria or the one or more second criteria, control the second device to deliver the respirophasic pacing.

[0075] Example 6: The system of any of examples 1 through 5, wherein the physiological activity comprises atrial activity and, based on the comparison, the processing circuitry is configured to control whether the first device delivers atrioventricular synchronous ventricular pacing based on sensing of the atrial activity via the accelerometer.

[0076] Example 7: The system of example 6, wherein the processing circuitry is configured to: based on the comparison satisfying one or more first criteria, control the first device to deliver ventricular pacing an atrioventricular interval after sensing an atrial contraction via the accelerometer; based on the comparison satisfying one or more second criteria, control the first device to deliver ventricular pacing an offset atrioventricular interval after sensing of the atrial contraction via the accelerometer; and based on the comparison not satisfying the one or more first criteria or the one or more second criteria, one of: control the first device to deliver non-atrioventricular synchronous ventricular pacing, control the first device to deliver atrioventricular synchronous ventricular pacingbased on trigger signals from the second device, or control the second device to deliver atrioventricular synchronous ventricular pacing.

[0077] Example 8: The system of any one or more of examples 3 to 5 or 7, wherein the processing circuitry is configured to adjust at least one of the one or more first criteria or the one or more second criteria based on an activity level of the patient.

[0078] Example 9: The system of any one or more of examples 1 to 8, wherein the first device is a medical device.

[0079] Example 10: The system of any one or more of examples 1 to 9, wherein the first device is configured for implantation within the patient.

[0080] Example 11 : The system of example any one or more of examples 1 to 10, wherein the first device is a leadless cardiac pacemaker.

[0081] Example 12: The system of any one or more of examples 1 to 11, wherein the second device is a medical device.

[0082] Example 13: The system of any one or more of examples 1 to 12, wherein the second device is configured for implantation within the patient.

[0083] Example 14: The system of any one or more of examples 1 to 13, wherein the second device is an extracardiac implantable cardioverter defibrillator.

[0084] Example 15: The system of any one or more of examples 1 to 14, wherein the processing circuitry comprises processing circuitry of at least one of: the first device; the second device; or a computing device configured to communicate with at least one of the first device or the second device.

[0085] Example 16: A method includes comparing sensing of physiological activity of a patient by a first device via an accelerometer to sensing of the physiological activity by a second device via a plurality of electrodes, wherein the first device is configured to deliver cardiac pacing; and based on the comparison, controlling whether the first device delivers the cardiac pacing based on the sensing of the physiological activity via the accelerometer.

[0086] Example 17: The method of example 16, wherein the physiological activity comprises respiration, and the cardiac pacing comprises respirophasic pacing.

[0087] Example 18: The method of any one or more of examples 16 or 17, wherein controlling whether the first device delivers the cardiac pacing based on the sensing of the physiological activity via the accelerometer comprises: based on the comparison satisfying one or more first criteria, controlling the first device to deliver phases of the respirophasicpacing timed to phases of respiration cycles sensed via the accelerometer; and based on the comparison satisfying one or more second criteria, controlling the first device to deliver phases of the respirophasic pacing offset relative to phases of respiration cycles sensed via the accelerometer.

[0088] Example 19: The method of any one or more of examples 16 to 18, wherein controlling whether the first device delivers the cardiac pacing based on the sensing of the physiological activity via the accelerometer comprises, based on the comparison not satisfying the one or more first criteria or the one or more second criteria, controlling the first device to deliver phases of the respirophasic pacing triggered by one or more commands from the second device.

[0089] Example 20: The method of any one or more of any of examples 16 to 19, wherein the second device is configured to deliver cardiac pacing, and controlling whether the first device delivers the cardiac pacing based on the sensing of the physiological activity via the accelerometer comprises, based on the comparison not satisfying the one or more first criteria or the one or more second criteria, controlling the second device to deliver the respirophasic pacing.

[0090] Example 21 : The method of any one or more of examples 16 to 20, further includes determining whether the second device is inaccurately sensing the physiological activity; and controlling, based on the determination, whether the first device delivers the cardiac pacing based on the sensing of the physiological activity via the accelerometer.

[0091] Example 22: The method of any one or more of examples 16 to 21, wherein the physiological activity comprises atrial activity, and controlling whether the first device delivers the cardiac pacing based on the sensing of the physiological activity via the accelerometer comprises controlling whether the first device delivers atrioventricular synchronous ventricular pacing based on sensing of the atrial activity via the accelerometer.

[0092] Example 23: The method of any one or more of examples 16 to 22, wherein controlling whether the first device delivers atrioventricular synchronous ventricular pacing based on sensing of the atrial activity via the accelerometer comprises: based on the comparison satisfying one or more first criteria, controlling the first device to deliver ventricular pacing an atrioventricular interval after sensing an atrial contraction via the accelerometer; based on the comparison satisfying one or more second criteria, controllingthe first device to deliver ventricular pacing an offset atrioventricular interval after sensing of the atrial contraction via the accelerometer; and based on the comparison not satisfying the one or more first criteria or the one or more second criteria, one of controlling the first device to deliver non-atrioventricular synchronous ventricular pacing, controlling the first device to deliver atrioventricular synchronous ventricular pacing based on trigger signals from the second device, or controlling the second device to deliver atrioventricular synchronous ventricular pacing.

[0093] Example 24: The method of any one or more of examples 18 to 20 or 23, further comprising adjusting at least one of the one or more first criteria or the one or more second criteria based on an activity level of the patient.

[0094] Example 25: The method of any one or more of examples 16 to 24, wherein the first device is a medical device.

[0095] Example 26: The method of example 25, wherein the first device is implanted within the patient.

[0096] Example 27: The method of example 26, wherein the first device is a leadless cardiac pacemaker.

[0097] Example 28: The method of any one or more of examples 16 to 27, wherein the second device is a medical device.

[0098] Example 29: The method of example 28, wherein the second device is implanted within the patient.

[0099] Example 30: The method of example 29, wherein the second device is an extracardiac implantable cardioverter defibrillator.

[0100] Example 31 : A non-transitory computer-readable medium storing instructions that when executed cause processing circuitry to: compare sensing of physiological activity of a patient by a first device via an accelerometer to sensing of the physiological activity by a second device via a plurality of electrodes, wherein the first device is configured to deliver cardiac pacing; and based on the comparison, control whether the first device delivers the cardiac pacing based on the sensing of the physiological activity via the accelerometer.

[0100] Example 32: A system includes a first device configured to deliver respirophasic pacing to a patient; a second device configured to sense respiration of thepatient; and processing circuitry configured to control the delivery of the respirophasic pacing by the first device based on the sensing of respiration by the second device.

[0101] Example 33: The system of example 32, wherein the first device is configured for implantation within the patient.

[0102] Example 34: The system of any of examples 32 or 33, wherein the first device comprises a leadless cardiac pacemaker.

[0103] Example 35: The system of any one or more of examples 32 to 34, wherein the second device is configured for implantation within the patient.

[0104] Example 36: The system of example 35, wherein the second device is an extracardiac implantable cardioverter defibrillator.

[0105] Example 37: The system of any one or more of examples 32 to 36, wherein the second device is configured to sense the respiration of the patient via a plurality of electrodes.

[0106] Example 38: The system of any one of examples 32 to 37, wherein the processing circuitry comprises processing circuitry of the second device, wherein the second device is configured to wireless transmit one or more messages to the first device to control the delivery of the respirophasic pacing by the first device.

[0107] Example 39: A method includes delivering respirophasic pacing to a patient by a first device; and controlling the delivery of the respirophasic pacing by the first device based on the sensing of respiration by a second device.

[0108] Example 40: The method of example 39, wherein the first device is implanted within the patient.

[0109] Example 41 : The method of example 40, wherein the first device comprises a leadless cardiac pacemaker.

[0110] Example 42: The method of any one or more of examples 39 to 41, wherein the second device is implanted within the patient.

[0111] Example 43: The method of example 42, wherein the second device is an extracardiac implantable cardioverter defibrillator.

[0112] Example 44: The method of any one or more of examples 39 to 43, further comprising sensing the respiration of the patient by the second device via a plurality of electrodes.

[0113] Example 45: The method of any one of examples 39 to 44, wherein controlling the delivery of the respirophasic pacing by the first device based on the sensing of respiration by the second device comprises, by the second device, wirelessly transmitting one or more messages to the first device to control the delivery of the respirophasic pacing by the first device.

[0114] Various examples have been described. These and other examples are within the scope of the following claims.

Claims

WHAT IS CLAIMED IS:

1. A system comprising:a first device comprising an accelerometer, the first medical device configured to:deliver cardiac pacing to a patient; andsense physiological activity of the patient sensed via the accelerometer; a second device configured to sense the physiological activity of the patient via a plurality of electrodes; andprocessing circuitry configured to:compare the sensing of the physiological activity by the first device to the sensing of the physiological activity by the second device; andbased on the comparison, control whether the first device delivers the cardiac pacing based on the sensing of the physiological activity via the accelerometer.

2. The system of claim 1, wherein the physiological activity comprises respiration, and the cardiac pacing comprises respirophasic pacing.

3. The system of claim 2, wherein the processing circuitry is configured to:based on the comparison satisfying one or more first criteria, control the first device to deliver phases of the respirophasic pacing timed to phases of respiration cycles sensed via the accelerometer; andbased on the comparison satisfying one or more second criteria, control the first device to deliver phases of the respirophasic pacing offset relative to phases of respiration cycles sensed via the accelerometer.

4. The system of claim 3, wherein the processing circuitry is configured to, based on the comparison not satisfying the one or more first criteria or the one or more second criteria, control the first device to deliver phases of the respirophasic pacing triggered by one or more commands from the second device.

5. The system of claim 3, wherein the second device is configured to deliver cardiac pacing, and the processing circuitry is configured to, based on the comparison notsatisfying the one or more first criteria or the one or more second criteria, control the second device to deliver the respirophasic pacing.

6. The system of claim 1, wherein the physiological activity comprises atrial activity and, based on the comparison, the processing circuitry is configured to control whether the first device delivers atrioventricular synchronous ventricular pacing based on sensing of the atrial activity via the accelerometer.

7. The system of claim 6, wherein the processing circuitry is configured to:based on the comparison satisfying one or more first criteria, control the first device to deliver ventricular pacing an atrioventricular interval after sensing an atrial contraction via the accelerometer;based on the comparison satisfying one or more second criteria, control the first device to deliver ventricular pacing an offset atrioventricular interval after sensing of the atrial contraction via the accelerometer; andbased on the comparison not satisfying the one or more first criteria or the one or more second criteria, one of:control the first device to deliver non-atrioventricular synchronous ventricular pacing,control the first device to deliver atrioventricular synchronous ventricular pacing based on trigger signals from the second device, orcontrol the second device to deliver atrioventricular synchronous ventricular pacing.

8. The system of any one or more of claims 3 to 5 or 7, wherein the processing circuitry is configured to adjust at least one of the one or more first criteria or the one or more second criteria based on an activity level of the patient.

9. The system of any one or more of claims 1 to 8, wherein the first device is a medical device.

10. The system of any one or more of claims 1 to 9, wherein the first device is configured for implantation within the patient.

11. The system of claim any one or more of claims 1 to 10, wherein the first device is a leadless cardiac pacemaker.

12. The system of any one or more of claims 1 to 11, wherein the second device is a medical device.

13. The system of any one or more of claims 1 to 12, wherein the second device is configured for implantation within the patient.

14. The system of any one or more of claims 1 to 13, wherein the second device is an extracardiac implantable cardioverter defibrillator.

15. The system of any one or more of claims 1 to 14, wherein the processing circuitry comprises processing circuitry of at least one of:the first device;the second device; ora computing device configured to communicate with at least one of the first device or the second device.

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