General overview and update of positive inotropic therapy.

Advances in our understanding of the pathophysiology of cardiac-ventricular failure and the pharmacophysiology of adrenergic receptors have greatly improved the short-term therapy of the low-output, hypotensive-hypoperfused, cardiac failure states. Agents are now specifically selected for these conditions on the basis of their predominant effects on the heart (positive inotropy) and the peripheral vasculature (vasodilatation or vasoconstriction). With the addition of dobutamine therapy, the pharmacophysiologic spectrum now includes norepinephrine (predominant vasopressor), dopamine (combined vasopressor-positive inotrope), dobutamine (predominant positive inotrope), and isoproterenol (combined positive inotrope-vasodilator). Digitalis was introduced to the medical profession 200 years ago. In terms of chronically administered positive inotropic therapy, to date, this "old-timer" has not been replaced. The yet experimental phosphodiesterase inhibitors, enoximone and milrinone, appear promising as long-term nonparenteral inotropes; however, the precise role, clinical effectiveness, and safety profile of these agents remain to be determined.