This study investigated the hemodynamic effects and tolerance of infusion of 10 micrograms/kg/min enoximone over 7 days in 12 patients (mean age 64.3 years) with severe chronic heart failure (10 NYHA Class III and 2 Class IV) with idiopathic dilated cardiomyopathy. Hemodynamic parameters were measured 10 minutes, 3 hours, 6 hours, 18 hours, 24 hours, and 7 days after the start of infusion. Catecholamines were assayed before the start of the infusion and on day 7. The heart rate increased on an average from 90.8 +/- 13.7 before infusion to 108.5 +/- 8.2 beats/min (p < 0.05) on day 7 (+20%). The mean arterial pressure decreased by approximately 10% (p < 0.05) between the start and end of the infusion. The pulmonary artery diastolic pressure dropped by a maximum of 30% at the 24th hour (23.1 +/- 5.1 to 16 +/- 5.4 mm Hg; p < 0.01). This decrease remained significant on day 7; the index cardiac was increased a maximum of 40% between the 18th and the 24th hour; p < 0.01). This increase was still significant on day 7 (2.35 +/- 0.44; p < 0.05; +22%). Finally, the decrease in systemic arterial resistance, which reached a maximum of 30% of the 24th hour, persisted on day 7 (-22%); 2076 +/- 451 to 1612 +/- 283 dynes/sec/cm5; p < 0.05). The norepinephrine level did not change significantly (4.5 +/- 1.2 nmol/l before infusion vs. 4.2 +/- 1.1 nmol/l on day 7). Infusion had to be stopped in one patient after 30 minutes because of prolonged severe hypotension.(ABSTRACT TRUNCATED AT 250 WORDS)