Renal scintigraphic captopril test in the diagnosis of renovascular hypertension.

Abstract

SUMMARY Angiotensin converting enzyme (ACE) inhibitor-induced renal failure has been reported in bilateral renal artery stenosis and in stenosis in solitary kidneys, but not in unilateral renal artery stenosis. In these patients, however, a functional impairment of the kidney ipsilateral to the stenosis can often be detected after ACE inhibition by scintigraphic techniques employing glomerular radionuclide tracers like 99n> Tc-diethylenetriamine pentaacetic acid (DTPA). Dynamic renal scintigraphy with "Tc-DTPA before and 1 hour after administration of captopril, 25 mg (renal scintigraphic captopril test; RSCT), was performed in a selected series of 39 hypertensive subjects with suspected renovascular hypertension. Changes in glomerular filtration rate induced by captopril on the individual kidney were estimated by assessing the early (120-180 seconds) DTPA uptake by the kidney. Values were expressed as the ratio between the kidney with the lower uptake and the contralateral one in 34 patients and as the ratio of the kidney counts to the injected dose in five patients with solitary kidneys, aortic coarctation, or both. Compared with precaptopril values, postcaptopril uptake decreased markedly in 14 subjects ( -62.42 ± 30.94 [SD]%; range, -25 to -100%) and decreased modestly or even increased in the other 25 ( + 0.57 ± 9.83%; range, + 28 to -13%). Of the 14 subjects considered to be RSCT-positive diagnostic workup revealed either established (10) or strongly suspected (2) renal artery stenosis in 12 and aortic coarctation in 2 subjects. In another patient with established renovascular hypertension, results of the RSCT were negative when performed in the supine position but became positive when repeated in the sitting position. Nine patients underwent repair of stenosis by either operation or angioplasty, and a striking correspondence was observed between response to RSCT and success of intervention. Taken together these findings strongly suggest that renal scintigraphy after ACE inhibition represents a promising tool for diagnosis of renovascular hypertension and its follow-up after operation or angioplasty. (Hypertension 10: 212-220, 1987) KEY WORDS • renovascular hypertension renal scintigraphy angiotensin converting enzyme inhibition

Prospective Study on Captopril Renography in Hypertensive Patients

“…Since the first reports on captopril-enhanced scintigra phy showing a sensitivity over 80% and a specificity close to 100% [17,18], the possibility of false-negative results in patients with very small ischemic kidneys and false positive results in cases of chronic renal parenchymal dis ease was widely recognized and the opportunity of an extensive study on a large series of patients was thought to be needed in order to justify the use of captopril-enhanced scintigraphy as first procedure in noninvasive screening test for RVH. Our results confirm, in a sample of 667 a priori unselected patients, that captopril-enhanced scin tigraphy is a reliable test, noninvasive, feasible even in high-risk patients, free of the nephrotoxic effects of the diagnostic procedures employing contrast media and that it has a definite role in the diagnostic screening of hyper tensive patients even in cases with preexisting renal im pairment, in which sensitivity and specificity have been a matter of debate [19], When a diagnosis of RAS is made, the fundamental problem is to discriminate between RAS coexistent with essential hypertension and RVH.…”

Captopril Renal Scintigraphy in Screening and Diagnosis of Renal Artery Stenosis - A Prospective Study

“…24 Fommei E at al (1987) reported positive captopril induced changes in Tc99m-DTPA scintigraphy which predicted patients who can be cured by revascularization or percutaneous transfemoral renal angioplasty (PTRA). 25 Mann S J et al (1991) compared usefulness of 131 I-OIH scintigraphy to be more accurate than Tc99m-DTPA. 26 captopril renal scintigraphy in RVH and showed that positive preoperative renal scintigraphy in strong predictor of hypertension curability of revascularization.…”

Introduction

“…This is reversible, as is the acute rise in plasma creatinine that accompanies administration of ACE inhibitors to patients with renovascular hyperten sion. This change in the isotopic renogram following captopril administration, together with the rise in plasma renin, can be used diagnostically to confirm renovascular hypertension [15],…”