The hemodynamic response to amrinone was analyzed in 19 patients with severe heart failure (NYHA III or IV). In 17 patients, 2 bolus of amrinone (0.75 mg/kg) were administered with an interval of 30 minutes, while a single bolus only was administered in 2 patients. In all patients the initial bolus was followed by continuous perfusion of Amrinone (10 micrograms/kg/min in 17 patients; 7 and 5 micrograms/kg/min in the remaining two). Cardiac index increased from 1.8 +/- 0.2 to 2.5 +/- 0.4 l/min/m2 (p less than 0.01), and pulmonary capillary wedge pressure and mean right atrial pressure decreased significantly (from 24 +/- 5.2 to 14 +/- 6 mmHg, p less than 0.01; and from 8.7 +/- 6.5 to 3.2 +/- 3.4, p less than 0.05 respectively). There were no significant changes in mean blood pressure (93 +/- 17 versus 88 +/- 13), heart rate (81 +/- 15 versus 84 +/- 14 beats per minute) and systolic work index (26.4 +/- 10.7 versus 37.7 +/- 12.3 g-m/m2). The maximum effect was obtained at 60 minutes and maintained throughout the period of monitoring (8 hours). In the 2 patients who received a single bolus of amrinone the maximum effect was reached at 30 minutes (cardiac index 1.3 +/- 0.1 versus 2.5 +/- 0.1 l/min/m2; pulmonary capillary pressure 24 +/- 5 versus 16.8 +/- 6.5 mmHg; mean right atrial pressure 11 +/- 1 versus 3.5 +/- 3.5 mmHg), and was followed by a progressive loss of efficiency, until effect had totally disappeared and situation basal returned, between the third and fourth hours.(ABSTRACT TRUNCATED AT 250 WORDS)