Apparatus and method for adjusting heart/pacer rate relative to cardiac pO.sub.2 obtain a required cardiac output
First Claim
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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Abstract
The apparatus for pacing a heart in accordance with the heart rate needed to produce a required cardiac output while the person is exercising, comprises a pacer adapted to be implanted in a human body and having a pulse generator and control circuitry (e.g. a microprocessor) therein, a pacing lead adapted to be implanted in a heart and having a distal electrode adapted to engage and supply pacing pulses to a right ventricle of a heart, and a pO2 sensor for sensing pO2 of the blood in the heart. An algorithm or routine utilizing same are stored in the control circuitry (microprocessor) and are adapted to relate pO2 and/or ΔpO2 with the required heart rate or change in heart rate, ΔR, needed to supply a desired cardiac output and to cause the pacer to pace the heart at the required heart rate when the heart is not naturally paced.
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Citations
25 Claims
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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:
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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. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 19, 20, 21, 22, 23, 24, 25)
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17. A method for pacing a heart in accordance with the heart/rate needed to produce a required cardiac output relative to the partial pressure of oxygen in the blood, pO2, while a person, whose heart is being paced, is exercising, said method comprising the steps of:
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implanting in a human body a demand pacer having control circuitry therein, a pulse gnerator coupled to said control circuitry and conventional sensing circuitry coupled to said control circuitry for sensing through a pacing lead heart electrical activity; implanting in a heart a pacing lead having a conductor therein and a tip electrode coupled to the conductor; placing the tip electrode in a ventricle of the heart; electrically coupling the lead to the pacer; providing an opening in a portion of the lead body which is proximal to the tip electrode and received in the heart; mounting a pO2 sensor in the opening for sensing the partial pressure (tension) of oxygen dissolved in the blood in the heart; sensing the pO2 in the heart with the pO2 sensor; determining with said control circuitry the partial pressure of oxygen pO2, in the blood from signals from the pO2 sensor; 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. ;determining the required rate needed to supply a desired cardiac output relative to the sensed pO2 including the steps of determining values of pO2 sensed;
determining changes in pO2 sensed;
relating the change, Δ
pO2, to a corresponding change in heart rate, Δ
R, between the maximum rate increase allowed, Δ
RMax.1., and the maximum rate decrease allowed, Δ
RMax.2 ;
adjusting the 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. ; andcausing 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. - View Dependent Claims (18)
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Specification