Atrial tracking in an intracardiac ventricular pacemaker

A non-transitory computer-readable medium storing a set of instructions which when executed by a control circuit of an intracardiac ventricular pacemaker having a motion sensor, cause the pacemaker to:

• produce by the motion sensor a motion signal comprising an atrial systolic event and a ventricular diastolic event indicating a passive ventricular filling phase and;
• 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;
• detect the atrial systolic event in response to the motion signal crossing the detection threshold;
• set an atrioventricular pacing interval in response to detecting the atrial systolic event;
• and
• deliver a pacing pulse upon expiration of the atrioventricular pacing interval to a ventricle of a patient's heart via electrodes coupled to the pacemaker.