In low-output cardiac failure with hypertension developing early after aortocoronary surgery, the currently preferred vasodilators nitroglycerin and nitroprusside proved to be equally successful and safe for the closed-loop control of mean arterial pressure. With NP- and NTG-induced MAP reduction to the present level of 80 mm Hg cardiac index increased similarly from 2.0 +/- 0.35 to 2.4 +/- 0.3 l/min/m2 (p less than 0.05) and from 1.9 +/- 0.29 to 2.2 +/- 0.26 l/min/m2 (p less than 0.05), respectively. Once adequate blood pressure fall was obtained, the addition of dobutamine at 6 micrograms/kg/min resulted under maintenance doses of NP and NTG averaging 1.6 +/- 0.4 and 4.6 +/- 1.8 micrograms/kg/min, respectively. A further improvement of cardiac performance manifested itself by cardiac index rise to 3.4 +/- 0.4 l/min/m2 (p less than 0.005) and 3.3 +/- 0.3 l/min/m2 (p less than 0.001), respectively. The NP-Db and NTG-Db regimens induced comparable reductions of rate - pressure-products reflecting a decrease of myocardial oxygen demands and facilitation of myocardial work.