Abstract
Summary
Changes in contractility indices for left ventricular muscle were calculated during air and oxygen breathing in 19 studies on 14 patients with coronary artery disease. The following significant changes were observed on oxygen breathing: rises in pO2 of arterial blood, in left ventricular systolic pressure, and in tension-time index, and a fall in the velocity of the shortening of the contractile element of the left ventricular muscle at zero load (V max). The fall in V max was similar even when heart rate was maintained constant. These observations suggest that oxygen breathing diminishes myocardial contractility and consequently may reduce myocardial oxygen demand. It is recognized that the reduction in myocardial contractility may be only one of the factors responsible for the decrease in myocardial oxygen demand induced by oxygen administration.
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