Cardiac pacemaker with selective unipolar/bipolar pacing

摘要

A dual chamber cardiac pacemaker is programmable for either unipolar or bipolar pacing of the atrium or the ventricle, independently of the pacing mode for the other chamber. Transistor switches are utilized for selectively connecting the various anodic electrodes to ground such that one of those electrodes is grounded at all times and isolation is maintained from circuit paths for non-selected modes. Switch control is effected using signals having the highest voltage level of proper polarity in the system, to assure maintenance of the selected switch states despite possible random voltages arising from external influences. Cumulative buildup of charge on coupling capacitors is prevented by selectively and actively discharging them after the respective chamber is paced.