Action of drugs in patients early after cardiac surgery. I. Comparison of isoproterenol and dopamine.

Dopamine and isoproterenol were each administered in two different doses to 12 patients with coronary artery disease in the period immediately after open heart surgery. The two doses of dopamine resulted in respective increases in cardiac output of 23 and 43 percent and reductions in systemic vascular resistance of 23 and 32 percent; neither dose significantly altered heart rate. The two doses of isoproterenol caused respective increases of 23 and 37 percent in cardiac output and 18 and 28 percent in heart rate and reductions in systemic vascular resistance of 22 and 29 percent. We conclude that lack of chronotropic effect of dopamine as compared with isoproterenol may make the former the agent of choice in patients requiring inotropic agents for their care in the early period after cardiac surgery.