Comparative effects of beta-adrenergic blockade in systolic hypertension according to age.

Hemodynamic variables were measured in 34 patients with isolated systolic hypertension before and after acute administration of propranolol. The patients were separated into two groups, those younger than and those older than 45 years of age, respectively. After drug administration, systolic pressure decreased significantly (P less than 0.001) in younger subjects with a concomitant increase in rapid ejection time (P less than 0.001). In the older patients, cardiac and peripheral factors determining systolic pressure were each altered after beta-adrenergic blockade. The most striking result was the reduction in systemic arterial compliance (P less than 0.01) probably due to unmasked alpha-adrenergic vasoconstriction. This arterial effect explains the lack of systolic pressure reduction despite a decrease in cardiac performance.