Intravenous nitroglycerin in acute myocardial infarction.

Vasodilator therapy has been shown to improve ventricular function in patients with left ventricular failure complicating acute myocardial infarction. Sublingual nitroglycerin also improves ventricular function in these patients but its effects are transient and variable. Infusion of intravenous nitroglycerin in 12 patients with acute infarction resulted in a decrease in left ventricular filling pressure from a mean of 22 plus or minus 2 mm Hg to 12 plus or minus 1 mm Hg (P less than 0.001) associated with a 7 mm Hg decrease in mean arterial pressure (P less than 0.05). Since stroke work index did not change significantly, this represents and improvement in ventricular performance and/or an alteration in ventricular compliance. All six patients in whom serial precordial mapping studies were performed showed a decrease in sigma ST (P less than 0.001). These findings suggest that intravenous nitroglycerin improved left ventricular function and decreased the extent of myocardial ischemia. Longer infusion may act to preserve borderline ischemic myocardium and thus limit infarct size.