Haemodynamic effects of saluretic treatment and beta-receptor blockade in patients with essential hypertension

The long-term haemodynamic effects of treatment with mefruside alone or in combination with alprenolol have been studied in nine patients with essential hypertension. After four months of mefruside therapy alone there was a significant decrease in intraarterial BP both at rest and during standardized leg exercise. Cardiac output and calculated total peripheral vascular resistance (TPVR) showed only minor mean decreases which were not statistically significant. Stroke volume tended to decrease and heart rate to increase. After another four months' treatment with addition of alprenolol there was a further significant decrease in intraarterial BP, related mainly to a further mean decrease in cardiac output which was not statistically significant. Heart rate decreased significantly, stroke volume was not significantly changed. Compared with the pretreatment levels, combination therapy induced a substantial decrease in intraarterial BP and a significant decrease in cardiac output both at rest in supine position and during standardized leg exercise. TPVR decreased slightly both at rest and during exercise but the change was not statistically significant. The results suggest that the decrease in BP after combined therapy with mefruside and alprenolol is mainly related to a decrease in cardiac output, the changes in TPVR being not significant. The additive hypotensive effect of alprenolol seems to be related in part to blocking of the increase in sympathetic activity that was found after treatment with mefruside alone.