Duplex ultrasonographic study of the renal arteries before and after renal artery stenting

Abstract

The aim of our study was to evaluate feasibility and accuracy of colour-coded duplex US in the detection of renal artery stenosis before and after stenting. Eighty-four patients (23 women, 61 men; mean age 64 years) with significant renal artery stenosis were studied with Doppler US, before and after stenting. A combined anterior and translumbar approach was used to visualise the renal arteries. Renal artery stenosis and in-stent restenosis were proved by the increase of renal peak systolic velocity (PSV) and reno-aortic ratio (RAR). Laboratory-specific threshold values of PSV and RAR were used to assess sensitivity and specificity of Doppler US. The renal arteries were visualised in all patients (feasibility 100%). A statistically significant difference of PSV and RAR was demonstrated between patent and stenotic renal arteries, before stenting, and between stenotic and stented renal arteries. No difference was demonstrated in cases of in-stent restenosis ( n=21). Before stenting, sensitivity of PSV and RAR was 93%, whereas specificity rates were 92 and 96%, respectively. After stenting sensitivity and specificity rates were, respectively, 90 and 93% for PSV, and 95 and 95% for RAR. Doppler US represents a feasible and reliable technique in the detection of renal artery stenosis and in-stent restenosis, although laboratory-specific threshold values are required to improve its accuracy.

Parâmetros diretos do duplex scan no diagnóstico da estenose da artéria renal: estudo de validação e otimização dos pontos de corte

“…The mean values ± SD of renal artery PSV presented a significant statistical difference (p < 0.005) between the groups with RAS 0-59% and RAS 60-99% (see table 3) in agreement with the results obtained in various publications 22,23,24 .…”

“…This result agrees with the findings of other authors who also demonstrated that by reducing the RAR cut-off point to values between 2.5 and 3.2, the sensitivity was increased which lowered the occurrence of false negatives 24,26,27,28 . On the other hand, Miralles and associates demonstrated that the RAR with a cut-off point of 3.3 presented low sensitivity and that this parameter did not contribute to lesion diagnosis when compared to the individual use of PSV 22 .…”

“…In contrast to these findings, Motew and associates obtained better results with a cut-off point of 180cm/sec than with the value of 200 cm/sec 23 and Napoli and associates preferred the cut-off point of 159 cm/sec rather than 180 cm/sec 24 , due to the higher sensitivity rates obtained with these limits.…”

Enhanced Flow Velocity after Stenting of Renal Arteries Is Associated with Decreased Renal Function

“…The PSV within the stenosis decreases. The sensitivity and specificity of the PSV measurement for in-stent restenosis reach 90 and 93%, respectively [7]. Thus, restenosis can reliably be diagnosed by direct measurement of in-stent flow.…”

“…Its parameters of direct vascular and indirect renoparenchymal scanning have been thoroughly evaluated for diagnostic sensitivity and specificity [6]. The immediate effects of renal artery stenting on the results of duplex scanning are well documented [7, 8]. Studies on ultrasound follow-up after renal artery intervention have mostly been done either in angioplasty without stenting [9] or were limited by the small patient number (18–28 patients) [8, 10] or short follow-up time [11].…”