Dual chamber pacing system with dynamic physiological tracking and

Abstract

A dual chamber pacemaker system is provided having means for determining when sensed atrial signals have a physiological rate, and tracking only such sensed atrial signals as are found to have physiological rates. The pacemaker provides logic means for continuously determining a physiological rate as a function of sensed atrial rate, whereby physiological rate substantially tracks the rate of sensed physiological atrial signals. The pacemaker also determines dynamic decision rates which are coupled to follow the physiological rate. The decision rates comprise a dynamic pacing limit, which sets the pacing escape interval; a dynamic tracking limit, which sets the upper limit of the physiological range of rates which are tracked; and the dynamic Wenckebach limit, which defines the upper rate for a dynamic Wenckebach range. The pacemaker enables time out of an AV delay for synchronizing delivery of ventricular pacing pulses with respect to atrial heartbeats which occur within the range between the dynamic pacing limit and the dynamic tracking limit, i.e., the physiological range. Synchronized ventricular pacing pulses are delivered when both the sensed atrial signal and the scheduled synchronized ventricular signal have rates within the determined physiological range. The pacemaker substantially continuously determines atrial rate, sensing all atrial signals except for a short PVAB which limits atrial sensing only to the extent required to block far field R-waves.