Effects of milrinone on left ventricular performance and myocardial contractility in patients with severe heart failure.

The potent vasodilating properties of the bipyridine derivatives confounds the assessment of changes in contractility as measured by peak positive left ventricular dP/dt and explains why the positive inotropic action of these agents has not been consistently demonstrated in patients with ventricular dysfunction. Therefore we studied the individual dose-response effects of intravenous milrinone on myocardial contractility as measured by peak positive left ventricular dP/dt in the context of concurrent changes in ventricular filling pressure. Incremental doses of milrinone caused a dose-related increase in peak positive left ventricular dP/dt in six of 11 patients. Peak positive left ventricular dP/dt was unchanged in four patients and reduced in one patient, all of whom experienced a substantial fall in left ventricular filling pressure. Thus milrinone has a definite inotropic effect in addition to its potent vasodilating properties.