Renal perfusion in experimental coarctation of the aorta during antihypertensive therapy.

Renal perfusion and the effectiveness of antihypertensive therapy were evaluated in experimental coarctation. A sham operation was performed at the age of two months on one group of dogs (n = 5); coarctation of the thoracic aorta was produced at the same age in a second group (n = 7) which was not treated with antihypertensive drugs; and coarctation was similarly produced in a third group (n = 6) which was treated with antihypertensive drugs; the drug treatment was begun one month after the coarctation operation. After operation, all dogs were observed for seven months under similar circumstances. With high doses of antihypertensive agents (hydrochlorothiazide 25 mg/day, propranolol 80 mg/day, and prazosin 20 mg/day), the blood pressure decreased significantly in the coarctation with treatment group compared with the coarctation without treatment group. Renal perfusion, when measured by xenon-133 washout at the age of five months, was similar in the coarctation without drug treatment and control groups but significantly lower (23% decrease, p less than 0.01) in the coarctation with drug treatment group; renal perfusion was similar in all three groups when measured at the ages of eight and nine months. The observed temporary decrease suggests a need to evaluate renal perfusion during antihypertensive treatment in coarctation in man.