Vasodilator therapy of pump failure complicating acute myocardial infarction.

In patients with pump failure complicating acute infarction, vasodilating drugs, by reducing impedance to left ventricular outflow and venous return to the heart, improve cardiac performance without affecting myocardial contractility. Sodium nitroprusside currently is the vasodilator of choice in most patients with both elevated left ventricular filling pressures and reduced cardiac output. Patients with accompanying mechanical defects, such as acute mitral regurgitation or ventricular septal rupture, are particularly amenable to vasodilator therapy. Some patients may require combined therapy, with inotropic catecholamines or mechanical assistance devices together with vasodilators, in order to avoid undesirable hypotension. Side effects and toxicity are rare when patients are carefully selected and monitored. It is uncertain whether vasodilators reduce ischemia or salvage jeopardized myocardium, but they appear to improve the initial prognosis of some patients with severe pump failure. The long-term prognosis of these patients remains poor, however, and therefore a more aggressive approach to their chronic management seems warranted.