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Apparatus and method for adjusting heart/pacer rate relative to cardiac pO.sub.2 obtain a required cardiac output

  • US 4,827,933 A
  • Filed: 05/15/1987
  • Issued: 05/09/1989
  • Est. Priority Date: 10/30/1986
  • Status: Expired due to Term
First Claim
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1. An implantable apparatus for pacing a heart in accordance with the heart/pacer rate needed to produce a required cardiac output relative to the partial pressure of oxygen in the blood in the heart, pO2, while the person having the apparatus implanted within his body is exercising, comprising:

  • a demand pacer, for implantation in the human body in a conventional manner, said pacer having control circuitry, a pulse generator coupled to said control circuitry and conventional sensing circuitry coupled to said control circuitry for sensing through a pacing lead heart electrical activity;

    a pacing lead for implantation in a heart, said lead being mechanically and electrically coupled to said pacer and including a lead body having a conductor therein and a tip electrode thereon coupled to said conductor, said tip electrode being placeable in a ventricle of the heart for supplying pacing pulses to the heart, and said lead having an opening therein which is located in a portion of the lead body that is proximal to said tip electrode and receivable in a heart;

    pO2 sensing means mounted in said opening for sensing the partial pressure (tension) of oxygen dissolved in the blood in a heart and for generating signals related to the pO2 sensed;

    condutor means in said lead coupled between said pO2 sensing means and said control circuitry;

    said control circuitry comprising a microprocessor including memory means for storing the relationship between Δ

    pO2 and Δ

    R, a maximum rate increase allowed, Δ

    RMax.1, a minimum rate decrease allowed Δ

    RMax.2, a minimum programmed pacing rate RMin. and a maximum programmed pacing rate RMax., means for relating a signal from the pO2 sensing means to the partial pressure of oxygen, pO2, in the blood, means for determining changes in the partial pressure of oxygen, Δ

    pO2, and for relating such changes to a corresponding change in pacer rate, Δ

    R, between the maximum rate increase allowed, Δ

    RMax.1, and the maximum rate decrease allowed, Δ

    RMax.2, means for adjusting the pacing rate R by adding Δ

    R to the present pacing rate R, to obtain a new pacing rate, R, between the minimum programmed pacing rate RMin. and the maximum programmed pacing rate RMax., needed to supply a required cardiac output relative to the pO2 measured, and means for causing the pacer to pace the heart at the newly calculated required pacing rate, R, when heart electrical activity is not sensed while the person is exercising.

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