An algorithm is implemented in a circuit for sensing P-waves in a pacemaker to
ensure ventricular pacing synchronization with sensed atrial depolarization waves.
VDD and VDDR pacing (atrial synchronized, ventricular inhibited pacing) are implemented
via a single standard ventricular pacing lead (unipolar or bipolar) and preferably
a subcutaneous electrode array (SEA). Specifically, an implanted ventricular lead
provides ventricular pacing and ventricular sensing while the SEA enable atrial
sensing, thus eliminating the need for an implanted atrial lead or a specialized
single pass VDD lead. The algorithm manages the sensed cardiac waves to effect
a desired pacing regimen based on the input from the single lead and SEA.
