Abstract: Implantable medical systems enter an exposure mode of operation, either manually via a down linked programming instruction or by automatic detection by the implantable system of exposure to a magnetic disturbance. A controller then determines the appropriate exposure mode by considering various pieces of information including the device type including whether the device has defibrillation capability, pre-exposure mode of therapy including which chambers have been paced, and pre-exposure cardiac activity that is either intrinsic or paced rates. Additional considerations may include determining whether a sensed rate during the exposure mode is physiologic or artificially produced by the magnetic disturbance. When the sensed rate is physiologic, then the controller uses the sensed rate to trigger pacing and otherwise uses asynchronous pacing at a fixed rate.

Abstract: Cardiac resynchronization therapy (CRT) delivered to a heart of a patient may be adjusted based on detection of a surrogate indication of the intrinsic atrioventricular conduction of the heart. In some examples, the surrogate indication is determined to be a sense event of the first depolarizing ventricle of the heart within a predetermined period of time following the delivery of a fusion pacing stimulus to the later depolarizing ventricle. In some examples, the CRT is switched from a fusion pacing configuration to a biventricular pacing configuration if the surrogate indication is not detected, and the CRT is maintained in a fusion pacing configuration if the surrogate indication is detected.

Abstract: An implantable medical device is configured to determine a first atrial arrhythmia score from ventricular events sensed by a sensing circuit of an implantable medical device and determine a second atrial arrhythmia score from an intraventricular signal comprising atrial mechanical event signals attendant to atrial systole and produced by a sensor of the implantable medical device. An atrial arrhythmia is detected based on the first atrial arrhythmia score and the second atrial arrhythmia score.

Abstract: A medical device is configured to produce a cardiac motion signal by sampling a signal produced by an axis of a motion sensor, starting a blanking period, suspending the sampling of the signal during at least a portion of the blanking period, and restarting the sampling of the signal at the sampling frequency before the blanking period has expired. The medical device may detect a cardiac event from the cardiac motion signal and generate a pacing pulse in response to detecting the cardiac event in some examples.

Abstract: An intracardiac ventricular pacemaker having a motion sensor, a pulse generator and a control circuit coupled to the pulse generator and the motion sensor is configured to identify a ventricular systolic event, detect a ventricular passive filling event signal from the motion signal, and determine a time interval from the ventricular systolic event to the ventricular passive filling event. The pacemaker establishes a minimum pacing interval based on the time interval.

Abstract: An intracardiac pacemaker system is configured to produce physiological atrial event signals by a sensing circuit of a ventricular intracardiac pacemaker and select a first atrial event input as the physiological atrial event signals. The ventricular intracardiac pacemaker detects atrial events from the selected first atrial event input, determines if input switching criteria are met, and switches from the first atrial event input to a second atrial event input in response to the input switching criteria being met. The second atrial event input includes broadcast atrial event signals produced by a second implantable medical device and received by the ventricular intracardiac pacemaker.

Abstract: An implantable medical device includes an activity sensor, a pulse generator, and a control module. The control module is configured to determine activity metrics from the activity signal and determine an activity metric value at a predetermined percentile of the activity metrics. The control module sets a lower pacing rate set point based on the activity metric value at the predetermined percentile.

Abstract: A medical device includes a motion sensor configured to sense a motion signal. The medical device includes a control circuit configured to determine at least one ventricular event metric from the motion signal sensed over multiple of atrial cycles, determine that the ventricular event metric meets atrioventricular block criteria and generate an output in response to determining the atrioventricular block.

Abstract: An implantable medical device is configured to determine a first atrial arrhythmia score from ventricular events sensed by a sensing circuit of an implantable medical device and determine a second atrial arrhythmia score from an intraventricular signal comprising atrial mechanical event signals attendant to atrial systole and produced by a sensor of the implantable medical device. An atrial arrhythmia is detected based on the first atrial arrhythmia score and the second atrial arrhythmia score.

Abstract: An implantable medical device system receives a cardiac electrical signal produced by a patient's heart and comprising atrial P-waves and delivers a His bundle pacing pulse to the patient's heart via a His pacing electrode vector. The system determines a timing of a sensed atrial P-wave relative to the His bundle pacing pulse and determines a type of capture of the His bundle pacing pulse in response to the determined timing of the atrial P-wave.

Abstract: An implantable medical device system includes a pacemaker and an implantable cardioverter defibrillator (ICD). The pacemaker is configured to confirm a hemodynamically unstable rhythm based on an activity metric determined from an activity sensor signal after detecting a ventricular tachyarrhythmia and withhold anti-tachycardia pacing (ATP) pulses in response to confirming the hemodynamically unstable rhythm. The pacemaker may deliver ATP when a hemodynamically unstable rhythm is not confirmed based on the activity metric. The ICD is configured to detect the ATP and withhold a shock therapy in response to detecting the ATP in some examples.

Abstract: A medical device includes a motion sensor configured to produce a motion signal and a control circuit configured to sense atrial events from the motion signal. In some examples, the control circuit is configured to set a ventricular diastolic event window and set a threshold amplitude during the ventricular diastolic event window for sensing an atrial event in response to the motion signal crossing the threshold amplitude during the ventricular diastolic window. The control circuit may determine a maximum amplitude of the motion signal during the ventricular diastolic event window for multiple ventricular cycles and determine an amplitude metric based on at least a portion of the determined maximum amplitudes. The control circuit may determine a target value of the threshold amplitude based on at least the amplitude metric and adjust the threshold amplitude toward the target value.

Abstract: Implantable medical systems enter an exposure mode of operation, either manually via a down linked programming instruction or by automatic detection by the implantable system of exposure to a magnetic disturbance. A controller then determines the appropriate exposure mode by considering various pieces of information including the device type including whether the device has defibrillation capability, pre-exposure mode of therapy including which chambers have been paced, and pre-exposure cardiac activity that is either intrinsic or paced rates. Additional considerations may include determining whether a sensed rate during the exposure mode is physiologic or artificially produced by the magnetic disturbance. When the sensed rate is physiologic, then the controller uses the sensed rate to trigger pacing and otherwise uses asynchronous pacing at a fixed rate.

Abstract: A medical device includes a motion sensor configured to produce a motion signal and a control circuit configured to set sensing control parameters and sense atrial events from the motion signal during ventricular cycles according to the sensing control parameters. In some examples, the control circuit is configured to determine a feature of the motion signal for at least some ventricular cycles, determine a metric of the motion signal based on the determined features, and adjust at least one of the sensing control parameters based on the metric.

Abstract: An intracardiac pacemaker system is configured to produce physiological atrial event signals by a sensing circuit of a ventricular intracardiac pacemaker and select a first atrial event input as the physiological atrial event signals. The ventricular intracardiac pacemaker detects atrial events from the selected first atrial event input, determines if input switching criteria are met, and switches from the first atrial event input to a second atrial event input in response to the input switching criteria being met. The second atrial event input includes broadcast atrial event signals produced by a second implantable medical device and received by the ventricular intracardiac pacemaker.

Abstract: An implantable medical device system receives a cardiac electrical signal produced by a patient's heart and comprising atrial P-waves and delivers a His bundle pacing pulse to the patient's heart via a His pacing electrode vector. The system determines a timing of a sensed atrial P-wave relative to the His bundle pacing pulse and determines a type of capture of the His bundle pacing pulse in response to the determined timing of the atrial P-wave.

Abstract: Implantable medical systems enter an exposure mode of operation, either manually via a down linked programming instruction or by automatic detection by the implantable system of exposure to a magnetic disturbance. A controller then determines the appropriate exposure mode by considering various pieces of information including the device type including whether the device has defibrillation capability, pre-exposure mode of therapy including which chambers have been paced, and pre-exposure cardiac activity that is either intrinsic or paced rates. Additional considerations may include determining whether a sensed rate during the exposure mode is physiologic or artificially produced by the magnetic disturbance. When the sensed rate is physiologic, then the controller uses the sensed rate to trigger pacing and otherwise uses asynchronous pacing at a fixed rate.

Abstract: An intracardiac ventricular pacemaker is configured to operate in in a selected one of an atrial-tracking ventricular pacing mode and a non-atrial tracking ventricular pacing mode. A control circuit of the pacemaker determines at least one motion signal metric from the motion signal, compares the at least one motion signal metric to pacing mode switching criteria, and, responsive to the pacing mode switching criteria being satisfied, switches from the selected one of the non-atrial tracking pacing mode and the atrial tracking pacing mode to the other one of the non-atrial tracking pacing mode and the atrial tracking pacing mode for controlling ventricular pacing pulses delivered by the pacemaker.

Abstract: A medical device is configured to set a post-atrial time interval in response to an atrial event and generate an event time signal in response to a ventricular electrical signal crossing an R-wave sensing threshold during the post-atrial time interval. The device accumulates oversensing evidence in response to the event time signal and adjusts a ventricular sensing control parameter based on the accumulated oversensing evidence in some examples.

Abstract: A medical device is configured to sense a cardiac electrical signal and determine from the cardiac electrical signal at least one of a maximum peak amplitude of a positive slope of the cardiac electrical signal and a maximum peak time interval from a pacing pulse to the maximum peak amplitude. The device is configured to determine a capture type of the pacing pulse based on at least one or both of the maximum peak amplitude and the maximum peak time interval.