Hemodynamic interaction of nonselective vs. beta-1-selective beta-blockade with hydralazine in normal humans

To assess the effects of nonselective vs. beta 1-selective beta-blockade on the hyperdynamic circulation induced by hydralazine, eight healthy volunteers received placebo, propranolol, 20 and 40 mg, and atenolol, 25 and 50 mg, on 5 separate days, followed by hydralazine (range 75 to 150 mg). Hydralazine decreased afterload (end-systolic wall stress) and increased venous return and left ventricular performance (by M-mode echocardiography). Both beta-blockers blunted the increases in heart rate, cardiac output, and venous return similarly, although heart rate and cardiac output were not completely normalized. Atenolol did not affect the hydralazine-induced decrease in afterload, whereas propranolol significantly opposed this change (P less than 0.03). The hyperdynamic circulation seen with hydralazine is mostly beta mediated, primarily beta 1. When given with hydralazine the two beta-blocker types differ primarily in their effects on afterload.