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Pacemaker and method of operating same that provides functional atrial cardiac pacing with ventricular support

  • US 5,873,895 A
  • Filed: 08/03/1998
  • Issued: 02/23/1999
  • Est. Priority Date: 11/13/1992
  • Status: Expired due to Term
First Claim
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1. A method of operating a dual-chamber electronic pacemaker in a positive AV hysteresis mode, the pacemaker having sensing means for sensing selected events, including the presence of AV conduction and AV block;

  • pulse generating means for selectively generating an atrial stimulation pulse (A-pulse) and a ventricular stimulation pulse (V-pulse);

    timing means for generating specified time intervals, including an AV interval, which time intervals start upon the sensing of prescribed events by the sensing means or the generation of specified stimulation pulses by the pulse generating means;

    control means for controlling the pulse generating means as a function of whether the sensing means senses certain prescribed events during a given time interval generated by the timing means;

    the method comprising;

    (a) setting the AV interval to a first value;

    (b) sensing whether AV conduction is present during the AV interval, and if so, keeping the AV interval set to its first value;

    (c) sensing whether AV block is present during the AV interval, and if so, issuing a V-pulse at the conclusion of the AV interval;

    (d) shortening the AV interval to a second value, less than the first value, after issuing the V-pulse in step (c);

    (e) sensing whether AV block continues after shortening the AV interval to its second value, and if so, keeping the AV interval at its second value;

    (f) sensing whether AV conduction is present after shortening the AV interval to its second value, and if so, resetting the AV interval to its first value;

    (g) sensing whether a prescribed length of time has elapsed since shortening the AV interval to its second value, and if so, resetting the AV interval to its first value in order to test for the return of AV conduction; and

    (h) repeating steps (b) through (g) for as long as the pacemaker is to be operated in the positive AV hysteresis mode;

    whereby the AV interval assumes either its first value or its second value as a function of whether AV conduction or AV block is sensed; and

    further whereby not more than the prescribed length of time ever elapses without testing for the return of AV conduction.

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