Renal duplex ultrasound findings in fenestrated endovascular aortic repair for juxtarenal aortic aneurysms

Objective This study characterized duplex ultrasound (DUS) findings and clinical outcomes associated with covered stent placement in renal arteries during fenestrated endovascular aortic repair (FEVAR) to determine if velocity criteria for native renal artery stenosis can be applied. Methods Data from a prospectively maintained database of patients who underwent FEVAR between January 2010 and August 2014 were obtained before FEVAR (preoperative or baseline) and at follow-up assessments at 30 days, 6 months, and 1, 2, and 3 years. The established DUS threshold criteria for ≥60% stenosis in native renal arteries were applied at baseline and all follow-up intervals: renal artery peak systolic velocity (PSV) ≥200 cm/s or renal-aortic velocity ratio (RAR) ≥3.5. Results Forty-nine patients underwent placement of 88 covered renal artery stents during FEVAR. At least 30-day follow-up was available for 43 patients with 80 stents. A ≥60% stenosis was identified in seven renal arteries of six patients on baseline DUS, and these patients were analyzed separately. The remaining 73 renal arteries were classified as normal or <60% stenosis at baseline, with a median PSV of 121 cm/s (interquartile range, 96-143) and median RAR of 1.4 (interquartile range, 1.1-1.7). No significant differences were found between the baseline and follow-up PSV measurements at any time point. The RAR differed significantly at some time points, although median values remained below the ≥60% stenosis threshold. Some increased RAR values were attributed to low aortic velocities after repair. In the 13 patients with 17 covered renal artery stents found to have PSV or RAR exceeding a DUS threshold for ≥60% native renal artery stenosis, there was no evidence of stenosis by computed tomography angiography, of renal dysfunction by estimated glomerular filtration rate, or of renal volume decrease by three-dimensional analysis. None of the seven renal arteries with ≥60% stenosis at baseline showed evidence of restenosis at 1, 2, or 3 years. Conclusions Covered stent placement in nonstenotic renal arteries during FEVAR is safe and durable, with PSV and RAR remaining in the normal or <60% stenosis range in most patients. Increases in PSV or RAR that occur are not associated with clinically significant sequelae or in-stent stenosis on computed tomography angiography. DUS velocity criteria for stenosis in native renal arteries appear to overestimate the severity of stenosis in covered stents after FEVAR.