Abstract: A feature named “atrial tracking recovery” (ATR) provides for restoring delivery of cardiac pacing therapy upon identification of an atrial refractory sense-ventricular sense (AR-VS) pattern of cardiac activity. In one embodiment, such patterns are monitored to determine if they are terminable. Once the AR-VS pattern is identified, the then operative post-ventricular atrial refractory period (PVARP) is shortened to allow sensing of the atrial event, which previously was unable to initiate a sensed atrioventricular (SAV) interval. Subsequent SAV intervals are shortened until an atrial event is sensed so that a ventricular pacing stimulus is delivered after the SAV interval expires. Since the SAV interval is normally programmed to an interval that is shorter than the intrinsic conduction time, ventricular pacing stimulus is provided after the SAV ends, thereby effectively restoring delivery of a ventricular pacing modality such as cardiac resynchronization therapy (CTR).

Abstract: A feature named “atrial tracking recovery” (ATR) provides a means of restoring delivery of cardiac pacing therapy upon identification of an AR-VS pattern of cardiac activity. The present invention incorporates a method of monitoring such patterns to determine if they are terminable. Once the AR-VS pattern is identified, according to the present invention the PVARP is shortened to allow sensing of the atrial event, which previously was unable to initiate an SAV interval. Subsequent SAV intervals are shortened until an atrial event is sensed so that a ventricular pacing stimulus is delivered after the SAV interval expires. Since the SAV interval is normally programmed to an interval that is shorter than the intrinsic conduction time, ventricular pacing stimulus is provided after the SAV ends, thereby effectively restoring delivery of a ventricular pacing modality such as cardiac resynchronization therapy (CRT).