Renovascular Hypertension Identified by Captopril-Induced Changes in the Renogram

SUMMARY Radloisotope renography was performed in 21 patients with hypertension and unilater-al renal artery stenosis with and without premeditation with 25 mg of captopril, and the results were compared with the effect of percutaneous transluminal angioplasty on the blood pressure, assessed 6 weeks after angioplasty. Angioplasty caused a considerable decrease in blood pressure in 15 of the 21 patients. In 12 of these 15 patients, captopril induced changes in the time-activity curves of the affected kidney only, suggesting deterioration of the excretory function of that kidney, while the function of the contralateral kidney remained normal. After angioplasty the asymmetry in the time-activity curves diminished despite identical pretreatment with captopril. Such captopril-induced unilateral impair-ment of the renal function was not seen in the six patients with unilateral renal artery stenosis whose blood pressure did not change after percutaneous transluminal angioplasty or hi 13 patients with hypertension and normal renal arteries. The functional impairment of the affected kidneys was characterized by a decrease of •'•Tc-diethylenetriamine pentaacetic acid uptake and a delay of I3II-hippurate excretion, while the ulI-hippurate uptake remained unaffected. These data are in agree-ment with a reduced glomerular filtration rate and diuresis during preservation of the renal blood flow, changes that can be expected after converting enzyme inhibition in a kidney with low perfusio