The measurement of coronary blood flow, oxygen consumption, and efficiency of the left ventricle in man

The left ventricular coronary blood flow and left ventricular oxygen consumption per unit weight have been determined in twenty-six patients by means of the nitrous oxide method in conjunction with catheterization of the coronary sinus. The studies were performed on normal individuals and on patients with various forms of cardiovascular disease. The technique of coronary sinus catheterization and of the nitrous oxide method as applied to the coronary circulation in man have been presented. In the normal subject the left ventricular coronary blood flow per 100 grams per minute and the left ventricular oxygen consumption per 100 grams per minute averaged 65 c.c. and 7.8 c.c, respectively. The average oxygen extraction was 12 volumes per cent. In acutely anemic patients the left ventricular coronary blood flow per 100 grams per minute was slightly increased, whereas the left ventricular oxygen consumption per 100 grams per minute and the left ventricular oxygen extraction were reduced. In patients with essential hypertension, left ventricular coronary blood flow per 100 grams per minute, left ventricular oxygen consumption per 100 grams per minute, and left ventricular oxygen extraction were normal. In patients with coarctation of the aorta, the average left ventricular coronary blood flow per 100 grams per minute, left ventricular oxygen consumption per 100 grams per minute, and left ventricular oxygen extraction were all increased. In congestive failure due to mitral stenosis and insufficiency and to arteriosclerotic heart disease the left ventricular coronary blood flow per 100 grams per minute, was normal. The oxygen extraction was slightly elevated. Despite clinical and radiological evidence of marked left ventricular enlargement, the oxygen consumption per 100 grams per minute was only slightly elevated. Left ventricular coronary blood flows per 100 grams per minute were increased in patients with aortic insufficiency, arteriovenous fistula, and hyperthyroidism. The left ventricular coronary blood flow was normal in the patient with aortic stenosis. The left ventricular oxygen consumption per 100 grams per minute was normal in patients with aortic stenosis, with arteriovenous fistula, and with hyperthyroidism. It was elevated in the patient with aortic insufficiency. In one patient with clinical and electrocardiographic evidence of coronary occlusion with myocardial damage, the left ventricular coronary flow per 100 grams per minute, the oxygen extraction, and the left ventricular oxygen consumption per 100 grams per minute were markedly reduced. The results indicate that chronic increase in the energy requirements of the heart were met, not by an increase in the oxygen consumption per unit weight, but by an increase in the total oxygen consumption due to hypertrophy. The efficiency of the failing heart was low as a result of markedly decreased work in conjunction with slightly increased oxygen consumption.