Multi-site hybrid hardware-based cardiac pacemaker

A cardiac pacemaker, comprising:

• a cardiac cycle interval (CCI) timer, resetting of which defines a cardiac cycle;
• a CCI compare register for storing a specified CCI limit value;
• a CCI comparator for generating a timer expiration signal when an output of the timer equals the CCI limit value;
• a first ventricular sensing/pacing channel comprising an electrode for disposing near a ventricle of the heart, a stimulus generator for outputting pacing pulses, and a sense amplifier for detecting ventricular depolarization signals;
• a combinational logic array for generating sense signals from the detected depolarization signals, for triggering the stimulus generator to generate a pacing pulse upon expiration of the CCI timer, and for resetting the CCI timer upon generation of a ventricular sense signal or pacing pulse;
• and,
• a microprocessor-based controller for updating the compare register between cardiac cycles in accordance with instructions programmed therein.