Vitafin N.v.

Wim Boute

Frederik H Wittkampf

Gerrit W Van Arragon

A programmable dual chamber cardiac pacemaker is provided which provides improved means for responding to sensed high atrial rates. The pacemaker monitors the sensed high atrial rates and determines whether they are physiological or not, and automatically controls the operative atrial refractory period as a function of whether or not the atrial rate is physiological. The pacemaker is permitted to go into a Wenckebach mode of operation only when it is determined that a sensed high atrial rate is physiological, and that under other conditions will automatically go into a block mode of operation.

Dual chamber pacemaker with automatic high rate limit mode determination

An improved cardiac pacemaker adapted to be programmed into one of a plurality of given modes of operation, including dual chamber modes, and in particular synchronous operation for pacing the patient's ventricle following detection of natural atrial heartbeats. The pacemaker has means for monitoring the time relationship between delivered ventricular stimulus pulses and next succeeding atrial heartbeats, for determining the occurrence of pacemaker induced retrograde P waves, or pacemaker caused tachycardia. The timing, and thus the rate of sensed P signals is processed to determine the desirability of establishing a special P sense window for looking for the occurrence of P signals at rates above a normal maximum operating rate, in which event the stability of the V-A timing is monitored in accordance with predetermined criteria to determine the existence of pacemaker mediated tachycardia, which may be broken up by skipping a ventricular stimulus. During detection of atrial beats at a rate higher then the predetermined maximum operating rate, the synchronous ventricular stimulus rate is maintained at an average at or below the maximum rate, while maintaining a substantially constant A-V interval.

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Doesburg, Netherlands

Wim Boute