BASE-LINE AND POSTCAPTOPRIL RENAL BLOOD-FLOW MEASUREMENTS IN HYPERTENSIVES SUSPECTED OF RENAL-ARTERY STENOSIS

Renal blood flow (RBF) measurements using first-pass radionuclide angi ography with DTPA, a glomerularly filtered agent, failed to show signi ficant differences between normal and stenotic kidneys, Since MAG3 is an ideal agent for the study of RBF, this agent might be an attractive alternative tracer to detect differences in RBF. Methods: An angiogra phically controlled prospective study was performed in 48 hypertensive patients, in whom a diagnosis of renovascular hypertension was suspec ted on clinical grounds. The study was done to determine whether RBF m easurements using first-pass radionuclide angiography with Tc-99m-MAG3 could be helpful in the diagnostic work-up of the patients. Additiona lly, the study was done before and after ACE-inhibition. Results: On r enal angiography, 29 patients showed to have normal renal arteries (50 patients had normal kidneys and 8 patients had small kidneys). Ninete en patients had renal artery stenosis (13 uni- and 6 bilateral disease ), In the patients with normal kidneys, the mean value of RBF measurem ents ranged from 10.5% to 10.9% of cardiac output, Only small stenotic and small kidneys with normal renal arteries showed a significant red uced baseline RBF as compared with normal kidneys (both p < 0.05); thi s difference disappeared after ACE-inhibition only for the small kidne ys with normal renal arteries, In patients with stenosed kidneys, RBF tended to be reduced both at baseline and after captopril, but the dif ferences with normal kidneys were not statistically significant, After ACE-inhibition RBF increased in the majority of kidneys, but postcapt opril RBF data did not differ significantly from those at baseline, Co nclusion: RBF measurements using first-pass radionuclide angiography w ith Tc-99m-MAG3, either before or after ACE-inhibition, cannot reliabl y discriminate between patients with essential hypertension and patien ts with renal artery stenosis.