CONTRACTILE ELEMENT WORK: A MAJOR DETERMINANT OF MYOCARDIAL OXYGEN CONSUMPTION.

The study of the determinants of myocardial oxygen consumption during the past years has formed historical sequence. Left ventricular volume was determined by the thermal dilution technic (18). The error and reproducibility of this method have been presented Each study consisted of the simultaneous measurement of cardiac output, left ventricular and aortic pressures, heart rate, left ventricular volume and left ventricular coronary blood flow, and oxygen extraction. Alterations of the hemodynamic state were achieved by changing the degree of aortic obstruction, volume loading by the rapid infusion of 500 to 1,500 ml of whole blood or inotro-pism induced by the infusion of isoproterenol in a dose of 1 to 5 ,Ag per minute. At the conclusion of each experiment, the left ventricle with the interventricular septum was dissected from the remainder of the heart and was weighed.

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