IMMEDIATE EFFECTS OF HYDRALAZINE-ISOSORBIDE DINITRATE COMBINATION ON EXERCISE CAPACITY AND EXERCISE HEMODYNAMICS IN PATIENTS WITH LEFT-VENTRICULAR FAILURE

Resting hemodynamics improve during vasodilator administration in patients with congestive heart failure (CHF), but the effects of these agents on exercise is unknown. 22 patients with class II or III CHF performed bicycle exercise to symptomatic maximum before and 90 minutes after random double-blind administration of oral hydralazine (100 mg) and isosorbide dinitrate (40 mg)(11 patients, group 1) or placebo (11 patients, group 2). Exercise duration was unchanged after treatment in either group. Maximal oxygen consumption changed insignificantly in both groups, from 12.6 ± 1.2(SEM) to 13.6 ± 1.6 ml/kg/min in group 1, and from 11.7 ± 1.4 to 13.4 ± 1.7 ml/kg/min in group 2. Maximal cardiac index was unchanged in both group 1 (4.00 ± 0.33 to 4.41 ± 0.29 1/min/m2) and group 2 (4.11 ± 0.43 to 4.14 ± 0.42 1/min/m2). Systemic vascular resistance at peak exercise was also unchanged in both group 1 (14.1 ± 1.6 to 11.8 ± 1.0 units) and group 2 (14.7 ± 1.6 to 13.5 ± 1.6 units). At submaximal exercise (300 kilopond-meters/min), however, cardiac index after treatment increased in group 1 (0.51 ± 0.18 1/min/m2, p<0.05) and systemic vascular resistance decreased (-3.3 ± 1.3 units, p<0.05), but were unchanged in group 2. Thus, although vasodilators do not improve maximal exercise capacity acutely, they can improve hemodynamics at lower work loads which may, therefore, be better tolerated in patients with CHF.