Renovascular disease among patients referred for renal duplex ultrasonography

Abstract

This study was conducted to determine the prevalence of renal artery stenosis (RAS) among patients referred to a vascular laboratory in a university hospital, to identify those who are possible candidates for revascularization, and to determine the prevalence of other pathologies incidentally detected. Consecutive patients referred to our laboratory for exclusion of RAS were included. Color duplex ultrasound (DU) imaging of the abdominal aorta, renal vasculature, and kidney parenchyma was performed. The resistivity index of the kidney (RI) was measured, and 0.8 was used as a cutoff to identify those with severe kidney disease that could be excluded from an intervention. Incidental findings were also noted. A total of 324 patients were included from September 1998 to August 2003. Unilateral RAS was found in 14% and bilateral in 7%. Unilateral (1.5%) and bilateral (0.6%) renal artery occlusions were rare. The main reason for referral was uncontrolled (43%) and controlled hypertension (34%). Most patients (63%) were taking two or more antihypertensive drugs. The diagnostic yield was 22% among those using two drugs and 55% among those using three or more. In 46 patients (64%), the RI was <0.8. Seven cases of fibromuscular dysplasia were found (10% of RAS patients or 2% overall). Incidental findings were detected in 24% and were significant enough to alter management in 26% among those with such findings. Our study identified a RAS prevalence of 22% and a renal artery occlusion prevalence of 4%. There was a high yield for RAS in patients receiving three or more drugs; however, the yield was also significant among those receiving two or more. About two thirds of patients diagnosed with RAS were potential revascularization candidates, evidenced by a low RI. DU imaging is also very useful in detecting pathology that is significant to alter patients' management.