Hydralazine and isosorbide dinitrate: comparative central and regional hemodynamic effects when administered alone or in combination.

Central and regional hemodynamic studies were performed before and after the oral administration of 75 mg of hydralazine and/or 20 mg of isosorbide dinitrate in 15 patients with low-output congestive heart failure. Hydralazine increased mean cardiac output 17-25%, mean renal blood flow 19%, and limb blood flow 17% (all p < 0.05). Mean hepatic blood flow did not change significantly with hydralazine. Except for a small increase in cardiac output (6%, p < 0.05) at 30 minutes, isosorbide dinitrate did not significantly alter central, renal, hepatic or limb blood flow. Combining isosorbide dinitrate and hydralazine effected similar increases in cardiac output (17-24%, p < 0.05), renal (17%, p < 0.05) and limb (20%, p < 0.05) blood flow as those elicited by hydralazine alone. The combination did not significantly alter mean hepatic blood flow. Hydralazine, alone or combined with isosorbide dinitrate, increases renal and limb blood flow in congestive heart failure in proportion to the augmented cardiac output; isosorbide dinitrate alone does not alter blood flow to these regions. Neither drug (or combination) changes hepatic blood flow in this clinical setting.