[Determination of the optimal dose of captopril in the treatment of severe cardiac failure by hourly hemodynamic monitoring].

The optimal dose of Captopril was evaluated by hourly haemodynamic monitoring in 10 patients with chronic congestive cardiac failure (Stage IV of the NYHA Classification) after administration of 25 mg, 50 mg, and 100 mg of Captopril. A similar improvement was observed in all the parameters considered with all three dosages. At its peak effect (90 minutes) 25 mg of Captopril caused a fall in pulmonary capillary, and mean pulmonary artery pressures, and a fall in systemic resistance of 40%, 20% and 30% respectively; with 50 mg of Captopril, the effect was a fall of 36%, 24% and 35% respectively. The cardiac index rose by 17% with 25 mg of Captopril, 28% with 50 mg and 12% with 100 mg of Captopril. Although the fall in pulmonary capillary pressure remained significant up to the 6th hour, the improvement in cardiac index was not significant after the 3rd hour. After 8 days' treatment, plasma renin activity increased from 7.01 +/- 4.68 to 23.6 +/- 18.3 ng/ml/hour (p less than 0.02) and serum aldosterone fell from 1.175 +/- 386 p. moles/l to 497 +/- 277 p. moles/l (p less than 0.001). There was no correlation between basal plasma renin activity and pre- or post-therapeutic systemic resistances. The clinical and haemodynamic improvement was sustained after 2 months' treatment in 5 of these patients without side effects. Increasing the dosage of Captopril does not reinforce or prolong its action; moderate doses (25 mg) are as effective as high doses (100 mg). Captopril, which acts by inhibiting the renin- angiotensin-aldosterone system is the current treatment of choice in severe refractory cardiac failure.