Geometrical consequences of kissing stents and the Covered Endovascular Reconstruction of the Aortic Bifurcation configuration in an in vitro model for endovascular reconstruction of aortic bifurcation

ObjectiveKissing stents (KS) are commonly used to treat aortoiliac occlusive disease, but patency results are often lower than those of isolated stents. The Covered Endovascular Reconstruction of the Aortic Bifurcation (CERAB) technique was recently introduced to reconstruct the aortic bifurcation in a more anatomical and physiological fashion. The aim of this study is to compare the geometrical consequences of various stent configurations in vitro.MethodsAnatomic vessel phantoms of the aortoiliac bifurcation were created to accommodate stent configurations. Self-expandable nitinol KS, balloon-expandable covered KS, and two versions of the CERAB configuration were deployed, one with the iliac legs positioned inside the tapered part of the aortic cuff (1) and one with the legs deployed above this level (2). Computed tomography data were obtained to assess the geometry. The conformation ratio (D-ratio) was calculated by use of the ratio of the major and minor axes. The proximal mismatch area, mean mismatch area, and total mismatch volume were calculated.ResultsThe highest D-ratios were observed in the nitinol KS and the CERAB configuration, implying an ideal “double-D” shape. The proximal and mean mismatch areas were four- to sixfold lower in the CERAB (1) configuration when compared with nitinol KS and CERAB (2), respectively, whereas the covered KS had the highest mismatch area. Nitinol and covered KS had the largest mismatch volume, whereas the mismatch volume was the lowest in the CERAB (1) configuration.ConclusionsAlthough nitinol self-expandable stents have a high stent conformation, the lowest radial mismatch was found in the CERAB (1) configuration, supporting the hypothesis that the CERAB configuration is the most anatomical and physiological reconstruction of the aortic bifurcation. Within the CERAB configuration, the two limbs are ideally positioned inside the tapering portion of the cuff, minimizing mismatch.

Clinical RelevanceStents in kissing stent (KS) position have frequently been used to reconstruct the aortic bifurcation and several modifications exist. The 1-year primary patency rate of KS varies between 70%-100%, with a morbidity rate of 6% to 24%, including distal embolization in up to 8% of cases. The use of covered stents appears to improve patency rates. Various aspects of the KS configuration may affect patency rates, including the positioning of the stents and the discrepancy between the stented lumen and the aortic lumen, the so-called radial mismatch. The latter causes flow perturbations and thrombus formation, which, in turn, may decrease stent patency. Choosing a configuration with the lowest radial mismatch may thus be crucial.