EFFECTS OF NITROGLYCERIN ON MYOCARDIAL BLOOD FLOW IN MAN - MEASURED BY COINCIDENCE COUNTING AND BOLUS INJECTIONS OF 84RUBIDIUM

Myocardial blood flow was measured using 84Rb, given as a bolus, and a double coincidence counting system. Twenty-four normal subjects and 24 patients with coronary heart disease were studied. The tests revealed that under control conditions, values for myocardial blood flow are reproducible within 2.1 per cent. Myocardial blood flow and coronary flow fraction in normal subjects and patients with coronary artery disease increased after sublingually administered nitroglycerin. The increase was statistically significant in both groups at 45 seconds; however, a significant increase was noticeable at 90 seconds in arteriosclerotic patients only. The hemodynamic effects of nitroglycerin included a decrease in arterial systolic pressure, mean arterial pressure and left ventricular work. The data demonstrate an early increase in nutritional blood flow after nitroglycerin, thus suggesting a redistribution of blood flow within the heart muscle. The early direct cardiac action, together with the observed prolonged peripheral hemodynamic effects of the drug, may well explain its beneficial action. © 1969.