Renal artery duplex ultrasound criteria for the detection of significant in-stent restenosis.

OBJECTIVES To define velocity criteria by ultrasonography for the detection of hemodynamically significant (>60%) renal artery in-stent restenosis (ISR). BACKGROUND The restenosis rate after renal artery stenting ranges between 10% and 20%. While duplex ultrasound criteria have been validated for native renal artery stenosis, there are no uniformly accepted validated criteria for stented renal arteries. METHODS Vascular laboratory databases from two academic medical centers were retrospectively reviewed for patients who underwent renal artery stenting followed by duplex ultrasound evaluation and angiography (CT angiography or catheter angiography) as the gold standard. RESULTS A cohort of 132 stented renal arteries that had angiographic comparisons was analyzed. Eighty-eight renal arteries demonstrated 0-59% stenosis while 44 renal arteries revealed 60-99% stenosis by angiography. Both the mean peak systolic velocity (PSV) and the renal artery-to-aortic ratio (RAR) were significantly higher in renal arteries with 60-99% restenosis compared with those with 0-59% restenosis (PSV: 382 cm/sec ± 128 vs. 129 cm/sec ± 62, P<0.001; RAR: 5.3 ± 2.4 vs. 2.1 ± 1.0, P <0.001). The optimal PSV and RAR cutoffs for detecting 60-99% ISR were calculated by receiver operator characteristics curve analysis. The velocity criteria that are associated with these results will be discussed. CONCLUSION Duplex ultrasonography is an accurate technique to identify significant restenosis in stented renal arteries. The PSV and RAR cutoffs for detecting renal artery ISR are higher than those in native, unstented renal arteries. A normal duplex ultrasound after renal artery stenting virtually excludes significant restenosis.