The 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, 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 to 2 minutes after taking the drug. In two of these subjects, flow decreased to 10 to 23 per cent below control at 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 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.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/33059/1/0000445.pd