In Vitro Evaluation of Balloon-Expandable Chimney Grafts in the Renal Arteries Combined With the Endurant Endograft

Abstract

Purpose: To compare balloon-expandable covered stents (BECS) available for use as renal chimney grafts to the Advanta V12 approved for use with the Endurant endograft. Materials and Methods: A silicone model was manufactured based on preoperative computed tomography angiography (CTA) scans of a patient with a 7-cm juxtarenal aneurysm treated with an Endurant bifurcated endograft and an Advanta V12 covered stent for the 6-mm-diameter right renal artery. The model was placed in a flow box filled with a 37°C blood-mimicking solution equipped with a pulsatile pumping system (140/60 mm Hg). The tested BECS were the Advanta V12, the VBX, and the BeGraft+. A 36-mm-diameter Endurant II endograft with a 16-mm-diameter contralateral limb and a 6×59-mm BECS chimney graft were used in 9 consecutive tests (3 for each combination). After each implantation, the model was placed in the CT scanner, and 2 radiologists blinded to the test device independently measured the gutter areas and the patent chimney graft lumen at the level of the Endurant’s suprarenal stent, at the level of the chimney’s maximum curvature, and 10 mm inside the renal artery. The intraclass correlation coefficients (ICC) were calculated to assess interreader reliability. Results: The mean gutter areas were 19.3±7, 20.2±8, and 22.3±8 mm2 for the Advanta, VBX, and BeGraft+, respectively (all p>0.05). At the level of the aortic endograft’s suprarenal stent struts, the mean diameter of the Advanta V12, VBX, and BeGraft+ were 4.46±0.3, 4.12±0.4, and 4.12±0.3 mm, respectively (all p>0.05). At the level of the maximum chimney graft angulation, the mean diameters were 3.77±0.3, 4.16±0.1, and 3.74±0.3 mm, respectively (all p>0.05). In the right renal artery, the mean diameters were 3.91±0.2, 4.05±0.9, and 4.3±0.4 mm, respectively (all p>0.05). The ICCs varied between 0.7 and 0.9, indicating good agreement between readers. Conclusion: These in vitro findings showed comparable results between the Advanta V12 and the available BECS used in conjunction with the Endurant endograft according to the instructions for use. Further clinical evaluation is needed to confirm these results.