Pacemaker with improved inhibit and trigger control

Abstract

A pacemaker for providing optimized inhibit and trigger responses, operating in a VVD or AAD mode. For each pacemaker cycle, the pacemaker is controlled to time out a refractory interval, an inhibit interval or range following a refractory interval, and a trigger interval or range which follows the inhibit interval and ends at the time out of the scheduled escape interval. A signal sensed during the inhibit range results in no pace pulse delivery, the pacemaker goes to the trigger mode and extends the escape interval. Any signal thereafter sensed before the time out of the extended escape interval results in delivery of a trigger pulse and restarting of a new pacemaker cycle. If no signal is sensed during the inhibit range, any signal sensed during the trigger range results in generation of a trigger pulse and the start of a new pacemaker cycle. The overall result is that noise or other signals which occur within the inhibit range are inhibited without a trigger, with only a small extension of the escape interval so that pacing rate is not greatly affected. Any signal sensed in the trigger range results in delivery of a trigger pulse. The result is an optimized combination of inhibition and triggering which ensures pacing in the presence of any noise that is sensed with relatively minimized sacrifice in rate change and battery energy depletion.