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Cardiac stimulating apparatus and method for heart failure therapy

  • US 5,334,222 A
  • Filed: 11/03/1992
  • Issued: 08/02/1994
  • Est. Priority Date: 11/03/1992
  • Status: Expired due to Term
First Claim
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1. A method of operating an implantable cardiac stimulator implanted in a patient suffering from congestive heart failure, said cardiac stimulator being of the type having means for sensing atrial activity, means for sensing ventricular activity, means for sensing cardiac function of the heart, means for stimulating at least one ventricular chamber, and microprogrammable controller means coupled to said means for sensing said atrial activity, said means for sensing ventricular activity and said means for sensing cardiac function, said microprogrammable controller means controlling said means for stimulating said at least one ventricular chamber so as to issue ventricular stimulating pulses at computed AV delay intervals following the sensing of an atrial event, comprising the steps of:

  • (a) computing the electromechanical interval (EMI) of the patient'"'"'s heart using information derived from said cardiac function sensing means, said atrial sensing means and said ventricular sensing means;

    (b) computing the atrial cycle length (ACL) of the patient'"'"'s heart using information derived from said atrial sensing means;

    (c) changing the AV delay parameter of said pacemaker by a known increment from a previous value when it is determined that EMI is less than ACL;

    (d) using said cardiac function sensing means to determine whether each of the incremental changes in the AV delay parameter enhanced the cardiac function of the patient'"'"'s heart measured on a previous cycle;

    (e) repeating steps (a)-(d) until it is determined in step (d) that cardiac function degraded; and

    (f) adjusting the AV interval by a pre-programmed small time value.

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