US Patent 9468766 Sensing and atrial-synchronized ventricular pacing in an intracardiac pacemaker

An intracardiac pacemaker is configured to receive a cardiac electrical signal developed across a pair of electrodes coupled to the pacemaker and detect a crossing of a first sensing threshold of the cardiac electrical signal. A pacing escape interval timer is set to a first pacing escape interval in response to the cardiac electrical signal crossing the first sensing threshold. The pacing escape interval timer is adjusted if the cardiac electrical signal crosses a second sensing threshold during a time limit.