Diagnostic role of new Doppler index in assessment of renal artery stenosis

Sergio Chain,Gabriela Feldman,Juan Muntaner,Ricardo Ronderos,Sofia Berman,Ramón N Herrera,Javier Ochoa,Eduardo M Escudero,Hector Luciardi

doi:10.1186/1476-7120-4-4

Sergio Chain, Gabriela Feldman + Show 7 more

Open Access

https://doi.org/10.1186/1476-7120-4-4

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Abstract

BackgroundRenal artery stenosis (RAS) is one of the main causes of secondary systemic arterial hypertension. Several non-invasive diagnostic methods for RAS have been used in hypertensive patients, such as color Doppler ultrasound (US). The aim of this study was to assess the sensitivity and specificity of a new renal Doppler US direct-method parameter: the renal-renal ratio (RRR), and compare with the sensitivity and specificity of direct-method conventional parameters: renal peak systolic velocity (RPSV) and renal aortic ratio (RAR), for the diagnosis of severe RAS.MethodsOur study group included 34 patients with severe arterial hypertension (21 males and 13 females), mean age 54 (± 8.92) years old consecutively evaluated by renal color Doppler ultrasound (US) for significant RAS diagnosis. All of them underwent digital subtraction arteriography (DSA). RAS was significant if a diameter reduction > 50% was found. The parameters measured were: RPSV, RAR and RRR. The RRR was defined as the ratio between RPSV at the proximal or mid segment of the renal artery and RPSV measured at the distal segment of the renal artery. The sensitivity and specificity cutoff for the new RRR was calculated and compared with the sensitivity and specificity of RPSV and RAR.ResultsThe accuracy of the direct method parameters for significant RAS were: RPSV >200 cm/s with 97% sensitivity, 72% specificity, 81% positive predictive value and 95% negative predictive value; RAR >3 with 77% sensitivity, 90% specificity, 90% positive predictive value and 76% negative predictive value. The optimal sensitivity and specificity cutoff for the new RRR was >2.7 with 97% sensitivity (p < 0.004) and 96% specificity (p < 0.02), with 97% positive predictive value and 97% negative predictive value.ConclusionThe new RRR has improved specificity compared with the direct method conventional parameters (RPSV >200cm/s and RAR >3). Both RRR and RPSV show better sensitivity than RAR for the RAS diagnosis.

Highlights

Renal artery stenosis (RAS) is one of the main causes of secondary systemic arterial hypertension
We have made a comparative study of three Doppler US parameters: renal peak systolic velocity (RPSV), renal aortic ratio (RAR), and the new renal-renal ratio (RRR) for the diagnosis of RAS
We found with digital subtraction arteriography (DSA) 35 main stenotic renal arteries and 29 main normal renal arteries (Table 3)

Summary

Introduction

Renal artery stenosis (RAS) is one of the main causes of secondary systemic arterial hypertension. Renovascular hypertension might account for 1–5% of all cases of hypertension [1,2] It affects 15–30% of patients who have clinical criteria suggestive of renovascular hypertension as refractory hypertension to an appropiate three-drug treatment associated either with moderate impairment of renal function or with carotid, peripheral or coronary atherosclerotic disease. Atherosclerosis accounts for 90% of cases of RAS, and usually involves the ostium and the proximal segment of the main renal artery and the perirenal aorta. Fibromuscular dysplasia accounts for less than 10% of cases of RAS. Its prevalence increases with age, in patients who have diabetes, aortoiliac occlusive disease, coronary artery disease or hypertension [4]. Reports of end-stage renal disease indicate a prevalence of RAS of 10–22% [7,8]

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