Inhibition of Angiotensin-Converting Enzyme for Diagnosis of Renal-Artery Stenosis

Abstract

To determine its utility as an aid in diagnosis of renovascular hypertension, we administered nonapeptide converting-enzyme inhibitor (CEI) (which inhibits conversion of angiotensin I to angiotensin II) (0.25 mg per kilogram) to 14 unselected hypertensive patients undergoing bilateral renal-vein catheterization. In seven (Group I) predominantly unilateral disease was discovered by angiography (renal-artery stenosis in six and hydronephrosis in one); in the remaining seven (Group II) no renal-artery abnormality was found. In Group I, mean (±S.E.) ratio of involved to uninvolved renal-vein plasma renin activity (PRA) increased from 2.94±0.91 before to 8.36±2.94 after CEI (P<0.01). In Group II, the ratio (of the initially higher to the lower side) was 1.99±0.49 before and 1.17±0.07 after CEI (P>0.2). Post-CEI PRA was predicted by pretreatment PRA. Mean blood pressure fell in both groups after CEI, and the decrement was predicted by pre-CEl PRA. These data suggest that CEI can be of use at the time of renal-vein catheterization, serving to increase diagnostic accuracy by increasing the difference in PRA between the two sides when there is unilateral disease. (N Engl J Med 298:582–586, 1978)