The effects of the nonselective beta blocker, propranolol,on coartectomy-induced hypertension were evaluated relative to changes in cardiac function, sympathetic tone, and plasma renin activity (PRA). A randomized, placebo-controlled, double-blind, age-stratifled design was employed. Propranolol (n = 11, mean age 9.4 years) or placebo (n = 12, mean age 10.2 years) was started 2 days before surgery and continued until 6 days after surgery. In patients on placebo, systolic and diastolic blood pressure, heart rate, and cardiac index increased rapidly and peaked within 1 day after surgery. Over the ensuing days these increases gradually abated. Plasma epinephrine and PRA increased markedly within 12 hours after surgery, but returned quickly toward preoperative levels. In contrast, plasma norepinephrine increased more gradually and remained elevated longer. In patients on propranolol, systolic blood pressure, heart rate, cardiac index and PRA showed only negligibie increases. However, diastolic blood pressure, increased even faster with propranolol than with placebo but to the same extent. Plasma catecholamines showed similar increases on the two treatments. Only in the placebo group was the code broken in the intensive care unit because of hypertension uncontrolled by soidum nitroprusside; this occurred in 6 of 12 patients. We conclude that nonselective beta blockade ameliorates the hyperdynamic circulation and increase in systolic blood pressure following coartectomy. The initial increase in diastolic blood pressure following surgery in the propranolol group may have been caused by vascular beta-2-receptor blockade resulting in unopposed alpha-receptor-mediatedvasoconstriction.
ASJC Scopus subject areas
- Cardiology and Cardiovascular Medicine