CAPTOPRIL RENOGRAPHY IN THE DIAGNOSIS OF RENOVASCULAR HYPERTENSION

The administration of an angiotensin-converting enzyme (ACE) inhibitor transitorily reduces the GFR in a kidney with renal artery stenosis, effect that can be ascertained with scintigraphic studies using ACE in hibitors. We evaluated the clinical usefulness of captopril renography (CR) in the diagnosis of renovascular hypertension (RVH) in 51 hypert ensive patients in which this diagnosis was suspected. All subjects un derwent angiography and RVH was diagnosed when renal artery stenosis e xceded 60%, there was lateralization of renal vein renin or there was a concordant clinical outcome. Renography was performed 15 minutes aft er Lasix administration, using Tc-99m DTPA, before and 60 minutes afte r the oral administration of 50 mg of captopril. The scintigraphic cri teria for a positive test were a decreased split renal function, a del ayed peak uptake, a decreased excretion of DTPA and a prolonged transi t time. In three of 28 patients in whom angiography discarded RVH, CR was positive. In the 23 patients with confirmed RVH, CR was positive i n 10 of 12 with unilateral stenosis, in 3 of 8 with bilateral stenosis and 1 of 3 with stenosis in a transplanted kidney. The overall sensit ivity and specificity of the test for RVH was 60.9% and 89.2% respecti vely. There were no changes in blood pressure or adverse effects after captopril administration. We conclude that CR in RVH is useful to sel ect patients for further studies (angiography) and to perform a functi onal interpretation of angiographic alterations.