Dual chamber pacemaker
First Claim
1. A cardiac pacemaker having atrial terminal means for connection thereto of P signals representing atrial heartbeats and ventricular terminal means for connection thereto of generated ventricular stimulus Vst pulses, ventricular pulse generating means for generating and connecting said Vst pulses to said ventricular terminal means, atrial sensing means for sensing P signals connected to said atrial terminal means from the patient'"'"'s heart,measuring means for measuring when a sensed P signal follows a connected Vst pulse by a V-A time which is within a predetermined range,counting means for counting the number of successive P signals having a V-A time within said predetermined range, andskipping means for causing skipping of sensing of the next P signal within said predetermined range following sensing of a P signal which is counted as the nth successive P signal by said counting means, where n is a predetermined number.
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Accused Products
Abstract
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.
65 Citations
24 Claims
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1. A cardiac pacemaker having atrial terminal means for connection thereto of P signals representing atrial heartbeats and ventricular terminal means for connection thereto of generated ventricular stimulus Vst pulses, ventricular pulse generating means for generating and connecting said Vst pulses to said ventricular terminal means, atrial sensing means for sensing P signals connected to said atrial terminal means from the patient'"'"'s heart,
measuring means for measuring when a sensed P signal follows a connected Vst pulse by a V-A time which is within a predetermined range, counting means for counting the number of successive P signals having a V-A time within said predetermined range, and skipping means for causing skipping of sensing of the next P signal within said predetermined range following sensing of a P signal which is counted as the nth successive P signal by said counting means, where n is a predetermined number.
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11. A dual chamber cardiac pacemaker, having means for sensing atrial heartbeats and means for delivering ventricular stimulus pulses, comprising
monitoring means for monitoring the time relationships between said ventricular stimulus pulses and the respective succeeding atrial heartbeats of the patient, means for storing data reflective of a plurality of said monitored time relationships, and means for determining the occurrence of pacemaker mediated tachycardia in accordance with said data, and means for altering pacer operation in response to the determining of a said occurrence.
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13. A cardiac pacemaker having cyclical means for cyclically sensing P signals representative of a patient'"'"'s atrial heartbeats and generating stimulus pulses for delivery to a patient'"'"'s ventricle, further comprising
means for measuring the stability of the V-A intervalbetween a delivered ventricular stimulus pulse and the next succeeding atrial heartbeat and for determining the existence of tachycardia as a predetermined criteria of said measured V-A internal stability, said means for measuring including means for measuring the occurrence of a plurality of P signals each occurring within a predetermined time window following a respective prior ventricular stimulus pulse, and means for changing the operation of said cyclical means over at least a portion of a cycle following determination of the existence of tachycardia.
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21. A dual chamber cardiac pacemaker for pacing a patient in at least an A-V synchronous mode, having means for sensing P signals, A-V timeout means for timing out an A-V delay following a sensed P signal, said A-V delay normally being a predetermined time TAV, and means for generating a ventricular stimulus pulse for delivery to the patient at the time out of a said A-V delay,
further comprising means for timing out an atrial refractory period following each sensed P signal, which atrial refractory period corresponds to a predetermined maximum heartbeat rate; - and
control means for controlling said A-V timeout means (i) to delay initiation of timing out said A-V delay to the end of said atrial refractory period whenever a P signal is sensed before the end of said atrial refractory period, and (ii) to reduce the length of said A-V delay to a time less than TAV following each said delay of initiation. - View Dependent Claims (22, 23, 24)
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Specification