In 14 patients with severe congestive heart failure (CHF) due to ischemic heart disease or idiopathic dilated cardiomyopathy, the hemodynamic response to intravenous infusion of dobutamine (D) was compared to that of a new non-catechol, non-glycoside, inotropic and vasodilator agent, MDL-17,043 (MDL) administered in incremental intravenous doses. D and MDL produced comparable increases in cardiac index (L/min/m2) (1.8 +/- 0.4 to 2.9 +/- 0.8 and 1.7 +/- 0.3 to 3.3 +/- 0.6, respectively; both p = 0.001) and stroke volume index (ml/beat/m2) (24 +/- 8 to 35 +/- 9 and 22 +/- 7 to 39 +/- 11, respectively; both p = 0.001). Both D and MDL reduced left ventricular filling pressure (29 +/- 5 to 24 +/- 5 and 29 +/- 6 to 17 +2- 6 mm Hg, respectively; both p less than 0.05), and mean right atrial pressure (11 +/- 4 to 8 +/- 4 and 13 +/- 5 to 6 +/- 4 mm Hg, respectively; both p = 0.001). The overall changes in heart rate and mean arterial pressure were small with both D and MDL. However, MDL in comparison to D resulted in a significantly lower left ventricular filling pressure (p = 0.001), mean pulmonary arterial pressure (p = 0.001), and mean arterial pressure (p less than 0.05). The salutary hemodynamic effects of MDL on cardiac index and left ventricular filling pressure were sustained for an average of 9.6 hours, whereas the effects of D dissipated within 30 minutes of stopping the infusion. No serious adverse effects were noted during acute administration with either drug. Therefore, intravenous MDL may be a useful substitute for D in the acute therapy of severe CHF.