Rate adaptive pacemaker controlled by ejection fraction
First Claim
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1. A rate adaptive cardiac pacemaker comprising, in combination:
- (a) a pulse generator having timing means for establishing the rate at which cardiac stimulating pulses are produced;
(b) means for applying said stimulating pulses to cardiac tissue;
(c) means for developing a control signal proportional to at least one of residual fraction and ejection fraction of the heart; and
(d) means for applying said control signal to said timing means for varying the rate at which said cardiac stimulating pulses are produced as a function of the heart'"'"'s contractility.
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Abstract
A rate adaptive pacer designed to accommodate changes in a patient'"'"'s metabolic demand utilizes ventricular ejection fraction (EF) as the rate controlling parameter. Ejection fraction is measured by sensing intracardiac impedance at end-diastole and end-systole and then using these measurements to compute stroke volume (SV). Ejection fraction is the stroke volume divided by the end-diastolic volume. This calculated value of EF is processed by the pacemaker to determine the escape interval (pacing rate) through a simple conversion algorithm.
147 Citations
10 Claims
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1. A rate adaptive cardiac pacemaker comprising, in combination:
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(a) a pulse generator having timing means for establishing the rate at which cardiac stimulating pulses are produced; (b) means for applying said stimulating pulses to cardiac tissue; (c) means for developing a control signal proportional to at least one of residual fraction and ejection fraction of the heart; and (d) means for applying said control signal to said timing means for varying the rate at which said cardiac stimulating pulses are produced as a function of the heart'"'"'s contractility. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A rate adaptive pacemaker comprising, in combination:
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(a) an electronic pulse generator having variable timing means for determining the rate at which cardiac stimulating pulses are produced; (b) means for applying said pulses to the heart; (c) means for sensing intracardiac impedance variations occasioned by systolic events; (d) means responsive to said means for sensing intracardiac impedance for computing the ejection fraction of the heart; and (e) means for adjusting said timing means in relation to the computed ejection fraction. - View Dependent Claims (9, 10)
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Specification