EFFECTS OF SUBLINGUAL NITROGLYCERIN ON MYOCARDIAL BLOOD FLOW IN PATIENTS WITH CORONARY ARTERY DISEASE OR MYOCARDIAL HYPERTROPHY

Using selective intracoronary injections of xenon-133 in saline, the effect of sublingual nitroglycerin on myocardial blood flow was studied in nine patients undergoing cardiac catheterization. One normal patient showed a 14 per cent increase in flow, 1 1 2 minutes after drug administration, with a subsequent decline to 8 per cent below control at 6 minutes. Four of five patients with coronary artery disease showed increased flows of 3 to 13 per cent at 1 1 2 to 2 minutes after taking the drug. In two of these subjects, flow decreased to 10 to 23 per cent below control at 5 1 2 minutes. In the remaining three subjects with cardiomegaly and left ventricular hypertrophy, nitroglycerin produced a decrease of 7 to 12 per cent in myocardial blood flow at 1 1 2 minutes and a further reduction to 15 to 17 per cent below control in two of the subjects at 5 minutes. These results are felt to substantiate the theory that in some patients with coronary artery disease, nitroglycerin exerts a biphasic action with an initial increase in myocardial blood flow followed by a decrease in flow as the systemic effects of the drug become manifest. This biphasic action was not seen in patients with cardiac enlargement and hypertrophy. © 1969.