Electronic system to distinguish between sinus and nonsinus atrial depolarizations which do not stimulate ventricular depolarizations in response to nonsinus atrial depolarizations

Claim 1

An electronic system for pacing a heart that distinguishes between sinus and nonsinus atrial depolarizations and that does not stimulate ventricular depolarizations in response to nonsinus atrial depolarizations, comprising: an electric lead having first and second ends; at least two electrodes; means attaching one electrode to a first end of the lead and means attaching the other electrode to the lead for location in the right atrium when the first end is implanted in the right atrial appendage; a sensing circuit including an indifferent electrode connected to the second end of the electric lead, said sensing circuit for detecting voltage difference between one of the electrodes and the indifferent electrode and for detecting voltage difference between the two electrodes; a timing circuit connected to the sensing circuit said timing circuit for determining the time interval between the time a voltage difference is detected between one electrode and an indifferent electrode and the time a voltage difference is detected between the two electrodes; a logic circuit connected to the timing circuit said logic circuit for comparing the time intervals determined by the timing circuit to time intervals indicative of sinus atrial depolarizations; and a ventricular stimulating circuit connected to the logic circuit said ventricular stimulating circuit that does not stimulate ventricular depolarization when the comparison made by the logic circuit indicates that the immediately preceding atrial depolarization was nonsinus said ventricular stimulating circuit effective to stimulate ventricular depolarization only when an immediately preceding atrial contracting is a spontaneous or pacemaker stimulated sinus atrial depolarization.