Renovascular hypertension identified by captopril-induced changes in the renogram.

Abstract

Radioisotope renography was performed in 21 patients with hypertension and unilateral renal artery stenosis with and without premedication 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 impairment 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 in 13 patients with hypertension and normal renal arteries. The functional impairment of the affected kidneys was characterized by a decrease of 99mTc-diethylenetriamine pentaacetic acid uptake and a delay of 131I-hippurate excretion, while the 131I-hippurate uptake remained unaffected. These data are in agreement 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 perfusion and an active, renin-mediated autoregulation of the glomerular filtration rate. These data suggest that functional captopril-induced unilateral changes, shown by split renal function studies with noninvasive gamma camera scintigraphy, can be used as a diagnostic test for renovascular hypertension caused by unilateral renal artery stenosis.(ABSTRACT TRUNCATED AT 250 WORDS)

Simplified captopril renography in diagnosis and treatment of renal artery stenosis.

“…The results reported here extend our preliminary observations 38 and those of Geyskes and associates 12 that the presence of captopril-induced changes effectively differentiates functional from anatomic renal artery stenosis. We hypothesized that a normal precaptopril scan that remains normal after captopril administration suggests essential hypertension, perhaps in the setting of coincident but subcritical renal artery obstruction, and that an abnormal (using our criteria) precaptopril scan that does not change after drug administration indicates a fixed or irreversible renal ischemic lesion.…”

“…We also examined whether captopril induced changes in the scintigram. 12 A scan with captopril-induced changes was one in which a normal time to peak activity and/or glomerular filtration rate ratio became abnormal following the administration of the drug. A renal arteriogram was judged positive for atherosclerotic renal artery stenosis if an obstruction of greater than 75% was present.…”

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

“…Among these 4, two kidneys had stenosis of accessory RA with normal main RA and one kidney was poorly functioning. 11 Captopril Tc99m-DTPA Sensitivity-80%, Specificity-100% Nally JV et al (1988) 12 Captopril Tc99m-DTPA Sensitivity-100%, Specificity-100% Safakianakis GN (1989) 13 Captopril-131-OIH Sensitivity-100%, Specificity-100% Svetkey LP et al (1989) 14 Captopril Tc99m-DTPA Captopril-131-OIH Sensitivity-91%, Specificity-50% Sensitivity-80%, Specificity-42% Charles C et al (1990) 15 Captopril Tc99m-DTPA Without Captoril Sensitivity-91%, Specificity-93% Sensitivity-43-68% Kakizaki H et al (1992) 16 Captopril Tc99m-DTPA Sensitivity-86%, Specificity-100% Man SJ etv al (1992) 17 Captopril Tc99m-DTPA Sensitivity-93%, Specificity-95% 18 …”

“…27 As far as ACE inhibitor scintigraphy is concerned there are many studies available which are shown in Table 1, but yet there is no consensus on scintigraphy protocol including radiopharmaceutical, sequence of studies, ACE inhibitors, their dose and specific criteria. [8][9][10][11][12][13][14][15][16][17][18][19][20] Nally JV et al achieved the sensitivity and specificity of 100% and their criteria for positive test were decrease in maximum activity, delayed uptake, widening of peak activity and slowing the excretory phase. 12 But on contrary , Kumar r et al and Orellana P et al showed lower sensitivity of 44.4% and 60.9% respectively.…”

“…1 A large list of studies is available in the literature regarding the role of renal scintigraphy with Tc99m-DTPA and with other radioactive pharmaceutical agents, with or without captopril in screening and diagnosing patients with RAS with variable and concontrdictory results. [8][9][10][11][12][13][14][15][16][17][18][19][20] The exact role and accuracy of this investigation in screening of the patients with RAS is not established. With rapid advance in technique and radiotracer in nuclear medicine, there is need to find a suitable screening method for diagnosis of RAS.…”