Glomerular Filtration Rate Measured by 51Cr-EDTA Clearance: Evaluation of Captopril-Induced Changes in Hypertensive Patients with and without Renal Artery Stenosis

INTRODUCTION: Renal artery stenosis can lead to renovascular hypertension; however, the detection of stenosis alone does not guarantee the presence of renovascular hypertension. Renovascular hypertension depends on activation of the renin-angiotensin system, which can be detected by functional tests such as captopril renal scintigraphy. A method that allows direct measurement of the baseline and post-captopril glomerular filtration rate using chromium-51 labeled ethylenediamine tetraacetic acid (51Cr-EDTA) could add valuable information to the investigation of hypertensive patients with renal artery stenosis. The purposes of this study were to create a protocol to measure the baseline and post-captopril glomerular filtration rate using 51Cr-EDTA, and to verify whether changes in the glomerular filtration rate permit differentiation between hypertensive patients with and without renal artery stenosis. METHODS: This prospective study included 41 consecutive patients with poorly controlled severe hypertension. All patients had undergone a radiological investigation of renal artery stenosis within the month prior to their inclusion. The patients were divided into two groups: patients with (n=21) and without renal artery stenosis, (n=20). In vitro glomerular filtration rate analysis (51Cr-EDTA) and 99mTc-DMSA scintigraphy were performed before and after captopril administration in all patients. RESULTS: The mean baseline glomerular filtration rate was 48.6±21.8 ml/kg/1.73 m² in the group wuth renal artery stenosis, which was significantly lower than the GFR of 65.1±28.7 ml/kg/1.73m² in the group without renal artery stenosis (p=0.04). Captopril induced a significant reduction of the glomerular filtration rate in the group with renal artery stenosis (to 32.6±14.8 ml/kg/1.73m², p=0.001) and an insignificant change in the group without RAS (to 62.2±23.6 ml/kg/1.73m², p=0.68). Scintigraphy with technetium-99m dimercapto-succinic acid (DMSA) did not show significant differences in differential renal function from baseline to post-captopril images in either group. CONCLUSIONS: Captopril induced a decrease in the GFR that could be quantitatively measured with 51Cr-EDTA. The reduction is more pronounced in hypertensive patients with RAS

Tres casos de hipertención y Fístula Arteriovenosa Renal: con una fístula de novo

Fístula Arteriovenosa Renal (FAVR) é uma causa rara e potencialmente reversível de hipertensão e insuficiência renal e/ou cardíaca. O tratamento da FAVR visa preservar o máximo de parênquima renal e, concomitantemente, erradicar os sintomas e efeitos hemodinâmicos decorrentes da FAVR. No presente estudo, serão relatados três casos de FAVR, incluindo um caso de FAVR idiopática de novo, que se apresentaram com hipertensão e insuficiência renal e/ou cardíaca, e descrever a terapêutica adotada e os resultados obtidos.The Renal Arteriovenous Fistula (RAVF) is a rare and potentially reversible cause of hypertension and kidney and/or heart failure. The treatment of RAVF aims at preserving the most of the renal parenchyma and, concomitantly, eradicating the symptoms and hemodynamic effects caused by the RAVF. The present study reports three cases of RAVF, including one case of a de novo idiopathic RAVF, which presented with hypertension and kidney and/or heart failure and describes the therapeutic measures used to treat these patients as well as the outcomes.La Fístula Arteriovenosa Renal (FAVR) es una causa rara y potencialmente reversible de hipertensión e insuficiencia renal y/o cardíaca. El tratamiento de la FAVR busca preservar el máximo de parénquima renal y, concomitantemente, erradicar los síntomas y efectos hemodinámicos resultantes de la FAVR. En el presente estudio, se relatarán tres casos de FAVR, incluyendo un caso de FAVR idiopática de novo, que se presentaron con hipertensión e insuficiencia renal y/o cardíaca, y describir la terapéutica adoptada y los resultados obtenidos