Peripheral and Renal Vein Plasma Renin Activity in Coarctation of the Aorta

Fifteen patients (ages 4 to 21 years) with coarctation of the aorta were studied. Ten patients were catheterized prior to surgery and both peripheral and renal vein plasma renin activity (PRA) were measured. Twelve patients were operated upon and peripheral PRA was measured pre-operatively and during the acute (postoperative day 0 to 10) and long-term postoperative (M = 112 days) period. Three children, not as yet operated upon, have been catheterized. Prior to catheterization, each received a sodium restricted diet (less than 500 mg NaCl) for 48 hours. The peripheral plasma renin activity was within the range of normal both preoperatively (18 ± 10 ng/ml) and long-term postoperatively (12 ± 5 ng/ml) p > 0.1 . The three patients who received sodium restriction prior to catheterization showed borderline to moderately elevated peripheral and renal vein PRA, suggesting that the renin apparatus responded to appropriate stimulation. During the acute postoperative period, each patient had a transient elevation of peripheral PRA. This elevation might be a partial stimulus to aldosterone production in the acute postoperative period. There was no correlation between peripheral PRA and blood pressure levels in the postoperative period. It was concluded that the renin-angio-tensin system does not play a significant role in maintaining the chronic hypertension which is associated with coarctation of the aorta.