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Cardio-synchronous impedance measurement system for an implantable stimulation device

  • US 5,800,467 A
  • Filed: 12/13/1996
  • Issued: 09/01/1998
  • Est. Priority Date: 12/15/1995
  • Status: Expired due to Term
First Claim
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1. An implantable electrical system for delivering therapeutic shocks to a heart of a patient, the system comprising:

  • a lead, which extends into a ventricle of the heart, adapted for delivering electrical pulses;

    control means for selectively inducing the lead to deliver an impedance measurement excitation pulse and pacing pulses to the ventricle to regulate the function of the heart;

    measuring means, in response to the delivered excitation pulse, for measuring at least two instantaneous impedance measurements in the heart, wherein the impedance measurement excitation pulses are delivered to the heart at at least two different times during a measurement window to determine a single slope, the window being selected to coincide with contraction of the ventricle;

    means for determining an impedance slope based on the instantaneous impedance measurements, the impedance slope being indicative of contractility of the heart; and

    means for regulating the heart function based on the impedance slope.

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