Importance

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Abstract

A dual-chamber implantable pacemaker configured to operate in the DDD or DDDR mode automatically sets its AV (or PV) interval to an amount that is equal to the natural conduction time of a patient plus or minus a small prescribed amount, e.g., 1-100 msec. When set to a value that is less than the natural conduction time, preemptive ventricular pacing thus occurs at a time in the patient's cardiac cycle that is near when a natural ventricular contraction (an R-wave) would occur. Such ventricular pacing causes a mechanical contraction sequence of the patient's heart that differs from the natural contraction sequence following a natural depolarization, resulting in improved cardiac output. The pacemaker includes a pulse generator that generates ventricular stimulation pulses (V-pulses) at the conclusion of a pacemaker-defined AV (or PV) interval if no natural ventricular activity (an R-wave) is sensed during such AV (or PV) interval. The AV (or PV) intervals are automatically adjusted by the pacemaker to be a function of the natural conduction time sensed by the pacemaker, where the natural conduction time is the time between atrial activity (a sensed P-wave or a delivered A-pulse) and the subsequent natural ventricular activity (R-wave).

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First Claim