Effects of combined dopamine and nitroprusside therapy in patients with severe pump failure and hypotension complicating acute myocardial infarction.

In severe pump failure with hypotension complicating acute myocardial infarction, dopamine has been useful in raising arterial pressure by increasing myocardial performance and augmenting peripheral resistance. Once adequate blood pressure are obtained, vasodilators may be used to reduce peripheral resistance and thus enhance pump performance. Accordingly, the hemodynamic effects of dopamine and nitroprusside administration were monitored in eight patients who developed hypotension following an acute myocardial infarction. With dopamine therapy alone, mean arterial pressure averaged 84 +/- 3.6 mm Hg and mean left ventricular filling pressure 32 +/-7.9 mm Hg. The addition of nitroprusside, at doses ranging from 0.5 to 1.6 micrograms/kg/min, resulted in a decrease in arterial pressure to 75 +/- 2.4 mm Hg (p less than 0.01) and in left ventricular filling pressure to 23 +/- 7.2 mm Hg (p less than 0.001). Cardiac index increased modestly from 1.81 +/- 0.61 to 2.01 +/- 0.60 liters/min/m2 (p less than 0.05), while systemic vascular resistance fell from 1,967 +/- 707 to 1,586 +/- 634 dynes-sec-cm-5 (p less than 0.01). Heart rate did not change significantly. Seven of eight patients died in the hospital within 4 days of admission. It appears that despite a beneficial hemodynamic response effected by combined dopamine-nitroprusside administration, the prognosis of this group of patients may not be favorably altered because of the extensive destruction of myocardium.