An atrial synchronized pacemaker having an adaptive atrial refractory period.

摘要

An atrial synchronized pacer having an atrial refractory period which is extended in response to the detection of retrograde activated P-waves for interrupting pacemaker meditated tachycardia. Atrial sensing amplifier 14 supplies atrial sense signals to A-V timer 20 and atrial refractory timer 30. After the A-V delay, timer 20 produces a ventricular pacing pulse, which may be delayed by upper rate limit timer 60. A V-A time measuring circuit 40 measures the times between ventricular and atrial pulses and if the times are both short and invariant, indicative of the detection of retrograde P-waves, atrial refractory control 50 operates to extend the atrial refractory period so that the pacer does not respond to the retrograde P-waves.