Patent ID: 7509168

Claim:
An implantable cardiac stimulation device comprising: a pulse generator that provides right ventricular and left ventricular pacing pulse pairs to a right ventricle and left ventricle of a heart in a biventricular pacing mode; a sensing circuit that senses activations of an atrium of the heart; and a pacemaker mediated tachycardia (PMT) detector comprising a timer that times a plurality of V-P intervals from first issued pacing pulses of each pacing pulse pair to sensed activations of the atrium, a limit/mode circuit that sets V-P interval limits responsive to the plurality of timed V-P intervals, and a compare circuit that determines if a last timed V-P interval is within the V-P interval limits; wherein the limit/mode circuit records the plurality of V-P intervals in a histogram and based on the histogram, determines whether a PMT is unimodal or bi modal to thereafter set V-P interval limits; wherein if the histogram indicates a unimodal distribution, the limit/mode circuit sets V-P interval limits below and above a single distribution peak of V-P intervals; and wherein if the histogram indicates a bi modal distribution, the limit/mode circuit establishes a lower limit below a distribution of a shorter V-P interval and an upper limit above a distribution of a longer V-P interval.