[Neurohumoral and hemodynamic effects in combination therapy of enoximone and dopamine]

Twelve patients with severe heart failure (NYHA class III-IV) were investigated by intraindividual comparison for the hemodynamic and neurohumoral effects of dopamine (3 and 6 micrograms/kg/min), enoximone (8 micrograms/kg/min), and the combination of both medications (dopamine 3 micrograms/kg/min+enoximone 8 micrograms/kg/min) using right heart catheterization. The duration of active treatment was 8 h for each substance with a subsequent washout time of 16 h. Dopamine led to a dose-dependent increase in cardiac index of 10-13% and 18-37% under 3 and 6 micrograms/kg/min, respectively (p < 0.001). Enoximone monotherapy produced a comparable increase in cardiac index between 27 and 32% (p < 0.001). Enoximone, but not dopamine, resulted in a significant decrease in mean pulmonary artery pressure (21-26%; p < 0.01), pulmonary capillary wedge pressure (24-30%; p < 0.01), and right atrial mean pressure (26-28%; p < 0.001). The systemic vascular resistance was without significant changes at low-dose dopamine therapy, decreased by 10-19% insignificantly at a dose of 6 micrograms/kg/min, and reached the level of significance with enoximone therapy (-20 to -25%; p < 0.001). There was a highly significant decrease by 49-55% in systemic vascular resistance with enoximone (p < 0.001), in contrast to dopamine. Heart rate and blood pressure remained without significant changes at low-dose dopamine, with the heart rate increasing significantly by 25% at a dose of 6 micrograms/kg/min within the first 2 h (p < 0.01). Enoximone produced a heart rate increase by 8-13% (being significant after 2 h; p < 0.05) with no changes in blood pressure. The combination therapy with dopamine and enoximone led to an additive increase in cardiac index by 35-43% (p < 0.001), a decrease in right atrial mean pressure by 28-36% (p < 0.01), a decrease in systemic vascular resistance by 27-30% (p < 0.01) and in pulmonary vascular resistance by 46-51%. An additive effect on heart rate was not observed. The respective monotherapies with low-dose dopamine and enoximone had no remarkable effect on plasma catecholamines, while dopamine at a dose of 6 micrograms/kg/min and combination therapy led to a significant increase in noradrenaline levels. There was a highly significant decrease in the plasma concentration of the atrial natriuretic factor under enoximone and combination therapy (p < 0.001) as well as a significant decrease in aldosterone (0 < 0.05).(ABSTRACT TRUNCATED AT 400 WORDS)