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Cardiac pacer with improved battery system, output circuitry, and emergency operation

  • US 4,590,941 A
  • Filed: 10/17/1983
  • Issued: 05/27/1986
  • Est. Priority Date: 03/02/1981
  • Status: Expired due to Term
First Claim
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1. An implantable tissue stimulator having at least one output channel, a plurality of parameter registers for rate and pulse intensity, stimulating logic means for producing an output signal to said output channel in accordance with the parameter values stored in said registers, wherein the improvement comprises:

  • said stimulating logic means including a crystal oscillator timing means and a digital circuit means for producing said pacing logic means output in accordance with said parameter registers;

    means for detecting an emergency condition and for generating an emergency mode signal;

    a continuously operating emergency oscillator separate from said crystal oscillator timing means and from said parameter registers for continuously producing an emergency output at a predetermined acceptable rate and predetermined pulse width both during non-emergency condition operation of said stimulator and during emergency condition operation of said stimulator;

    said emergency detecting means including means for checking the frequency of said crystal oscillator relative to the output of said emergency oscillator for producing an output indicative of failure of said crystal oscillator;

    gating means for substituting the output of said continuously operating emergency oscillator for the output of said stimulating logic means when said emergency detecting means produces an output indicative of failure of said crystal oscillator.

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