An instruction memory for a microprocessor based cardiac pacer is equipped with code means defining improved pacing routines for accomplishing a programmably selectable 2:1 block mode in which every other atrial sense output is automatically ignored above a programmed maximum atrial rate. The 2:1 block...http://www.google.com/patents/US4467810?utm_source=gb-gplus-sharePatent US4467810 - Multi-mode microprocessor-based programmable cardiac pacer
