The Geometry of Y-stent Configurations Used for Wide-Necked Aneurysm Treatment: Analyzing Double-Barrel Stents in vitro Using Flat-Panel CT.

Abstract: Background Stent-assisted coil embolization of wide-necked bifurcation aneurysms often employs a “Y-stent” configuration. A similar stent configuration, termed “kissing” or “double-barrel” (KDB), is used often at the aortoiliac bifurcation. Studies of KDB in aortoiliac disease show that rates of thromboembolic complication vary with the cross-sectional geometry of the stent pair, a function of the radial crush resistive force (CRF) of each stent. We assessed the cross-sectional geometry of intracranial stent pairs in an in vitro model of the basilar artery using flat-panel CT. Methods In a silicone model of a wide-necked basilar tip aneurysm, six simulated KDB stent deployment trials were performed using combinations of five stents (Enterprise 1, 2, Neuroform Atlas, LVIS, LVIS Jr.). Flat-panel CT reconstructions were used to assess cross-sectional stent geometries. Relative conformability, defined by ovalization and “D-ratio”, radial crush resistive force (CRF, predicted vs. actual), and radial mismatch fraction were compared by stent type (braided vs. laser-cut). Results Several distinct forms of cross-sectional stent geometry were observed. Braided stents had lower ovalization and D-ratio (p = 0.015) than laser-cut stents. The Atlas/LVIS combination yielded the lowest radial mismatch fraction (19.7% vs. mean 44.3 ±0.7%). Braided stents tended to have a deployed stent radius closer to the expected (nominal) diameter (i.e. higher relative CRF) than laser-cut stents (measured vs. nominal diameter discrepancy +38.6 ± 21.1% vs. -10.7 ±16.1%, p = 0.14), respectively. Conclusions In constant anatomy, the cross-sectional geometry of the KDB stent configuration will vary depending on the design and structure of the stents employed