To assess the inotropic, vasodilator, and after-load-reducing effects of intravenous milrinone in patients with severe congestive heart failure, a simple noninvasive echocardiographic study coupled with a right catheterization was performed in 12 patients. Milrinone was administered intravenously as a 50 micrograms.kg-1 bolus followed by a 24-h milrinone infusion at a rate of 0.5 mg.kg-1.min-1 [corrected]. Echocardiographic left ventricular end-diastolic diameter (Ded), end-systolic diameter (Des), and wall thickness were measured at baseline and at 24 h of milrinone infusion, before and after a sublingual nitrate administration (0.8 mg of nitroglycerin) that induced load variations. Hemodynamic measurements were performed simultaneously. Left ventricular end-systolic meridional wall stress (Ses) was then calculated. The slopes of percent fractional shortening (percent FS)/Ses and Ses/Des, obtained during sublingual nitrate administration, were traced. Both end-systolic relations are an index of the contractile state. Milrinone therapy improved hemodynamics in all patients, resulting in stabilized hemodynamic conditions between 12 and 24 h of continuous milrinone infusion. At these times, the cardiac index increased to 30% while the capillary pulmonary wedge pressure and systemic vascular resistance decreased to 26 and 24%, respectively (all p less than 0.01). The average slope of Ses/Des shifted upward from 47.5 +/- 30 to 69.25 +/- 34 (p less than 0.05) and the average slope of (percent FS)/Ses shifted from -0.032 +/- 0.025 to -0.082 +/- 0.061 (p less than 0.01), both variations attesting the inotropic effect of milrinone.(ABSTRACT TRUNCATED AT 250 WORDS)