Abstract: A pacemaker is configured to operate in an atrial synchronous ventricular pacing mode and, after expiration of a conduction check time interval, switch to an asynchronous ventricular pacing mode that includes setting a ventricular pacing interval to a base pacing rate interval. The pacemaker is further configured to determine when atrioventricular block detection criteria are satisfied during the asynchronous ventricular pacing mode and, responsive to the atrioventricular block detection criteria being satisfied, switch back to the atrial synchronous ventricular pacing mode.

Abstract: An intracardiac ventricular pacemaker is configured to detect a ventricular diastolic event from a motion signal received by a pacemaker control circuit from a motion sensor. The control circuit starts an atrial refractory period having an expiration time set based on a time of the detection of the ventricular diastolic event. The control circuit detects an atrial systolic event from the motion signal after expiration of the atrial refractory period and controls a pulse generator of the pacemaker to deliver a pacing pulse to a ventricle of a patient's heart at a first atrioventricular pacing time interval after the atrial systolic event detection.

Abstract: An intracardiac ventricular pacemaker having a motion sensor is configured to produce a motion signal including an atrial systolic event and a ventricular diastolic event indicating a passive ventricular filling phase, set a detection threshold to a first amplitude during an expected time interval of the ventricular diastolic event and to a second amplitude lower than the first amplitude after an expected time interval of the ventricular diastolic event. The pacemaker is configured to detect the atrial systolic event in response to the motion signal crossing the detection threshold and set an atrioventricular pacing interval in response to detecting the atrial systolic event.

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: A ventricular pacemaker is configured to determine a ventricular rate interval by determining at least one ventricular event interval between two consecutive ventricular events and determine a rate smoothing ventricular pacing interval based on the ventricular rate interval. The pacemaker is further configured to detect an atrial event from a sensor signal and deliver a ventricular pacing pulse in response to detecting the atrial event from the sensor signal. The pacemaker may start the rate smoothing ventricular pacing interval to schedule a next pacing pulse to be delivered upon expiration of the rate smoothing ventricular pacing 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 is configured determine a numerical value of a variable that is monitored by the implantable medical device and convert the numerical value to a data sequence of modulated electrical stimulation rate intervals. The implantable medical device delivers electrical stimulation pulses according to the data sequence of modulated stimulation rate intervals to cause a modulated rate of activation of excitable tissue of a patient corresponding to the modulated stimulation rate intervals. The modulated rate of activation is detectable by a rate monitor for demodulation to the numerical value of the monitored variable data value. In some examples, the implantable medical device is a pacemaker delivering cardiac pacing pulses according to modulated pacing rate intervals to cause a modulated heart rate of the patient detectable by a heart rate monitor for demodulation to the numerical value of the monitored variable.

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 is configured to detect a ventricular diastolic event from a motion signal received by a pacemaker control circuit from a motion sensor. The control circuit starts an atrial refractory period having an expiration time set based on a time of the detection of the ventricular diastolic event. The control circuit detects an atrial systolic event from the motion signal after expiration of the atrial refractory period and controls a pulse generator of the pacemaker to deliver a pacing pulse to a ventricle of a patient's heart at a first atrioventricular pacing time interval after the atrial systolic event detection.

Abstract: A pacemaker is configured to operate in an atrial synchronous ventricular pacing mode and, after expiration of a conduction check time interval, switch to an asynchronous ventricular pacing mode that includes setting a ventricular pacing interval to a base pacing rate interval. The pacemaker is further configured to determine when atrioventricular block detection criteria are satisfied during the asynchronous ventricular pacing mode and, responsive to the atrioventricular block detection criteria being satisfied, switch back to the atrial synchronous ventricular pacing mode.

Abstract: An intracardiac ventricular pacemaker having a motion sensor is configured to produce a motion signal including an atrial systolic event and a ventricular diastolic event indicating a passive ventricular filling phase, set a detection threshold to a first amplitude during an expected time interval of the ventricular diastolic event and to a second amplitude lower than the first amplitude after an expected time interval of the ventricular diastolic event. The pacemaker is configured to detect the atrial systolic event in response to the motion signal crossing the detection threshold and set an atrioventricular pacing interval in response to detecting the atrial systolic event.

Abstract: A medical device includes a motion sensor for producing a motion signal including cardiac event signals. The medical device generates a ventricular pacing pulse upon expiration of a pacing interval. The medical device determines a synchrony metric from the motion signal after a delivered ventricular pacing pulse and adjusts the pacing interval based on the synchrony 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 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: A medical device includes a motion sensor for producing a motion signal including cardiac event signals. The medical device generates a ventricular pacing pulse upon expiration of a pacing interval. The medical device determines a synchrony metric from the motion signal after a delivered ventricular pacing pulse and adjusts the pacing interval based on the synchrony metric.

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: The control module of a first pacemaker included in an implantable medical device system including the first pacemaker and a second pacemaker is configured to set a pacing escape interval in response to a far field pacing pulse sensed by the first pacemaker. The far field pacing pulse is a pacing pulse delivered by the second pacemaker. The pacing escape interval is allowed to continue without restarting the in response to a far field intrinsic event sensed by the first pacemaker during the pacing escape interval. The first pacemaker delivers a cardiac pacing pulse to the heart upon expiration of the pacing escape interval.

Abstract: A medical device is configured to generate an acceleration signal and a temperature signal. The device is configured to determine an activity metric from the acceleration signal that is representative of patient physical activity. In response to determining that the activity metric is equal to or greater than a previously determined activity metric, the device is configured to adjust a target cardiac pacing rate based at least on a temperature change determined from the temperature signal. The device may include a pulse generator for generating cardiac pacing pulses based on the target cardiac pacing rate.

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.