Alteration of intraaneurysmal hemodynamics for flow diversion using enterprise and vision stents

Objective Flow diversion is a novel concept for intracranial aneurysm treatment. The recently developed Enterprise Vascular Reconstruction Device (Codman & Shurtleff, Inc., Raynham, MA, USA) allows easy delivery and repositioning. Although designed specifically for restraining coils within an aneurysm, this stent has theoretical effects on modifying flow dynamics, which have not been studied. The goal of this study was to quantify the effect of single and multiple self-expanding Enterprise stents alone or in combination with balloon-mounted stents on aneurysm hemodynamics using computational fluid dynamics. Methods The geometry of a wide-necked, saccular, basilar trunk aneurysm was reconstructed from computed tomographic angiography images. Various combinations of one to three stents were "virtually" conformed to fit into the vessel lumen and placed across the aneurysm orifice. Computational fluid dynamics analysis was performed to calculate hemodynamic parameters considered important in aneurysm pathogenesis and thrombosis for each model. Results The complex aneurysmal flow pattern was suppressed by stenting. Stent placement lowered average flow velocity in the aneurysm; further reduction was achieved by additional stent deployment. Aneurysmal flow turnover time, an indicator of stasis, was increased to 114%117% for single-stent, 127%128% for double-stent, and 141% for triple-stent deployment. Furthermore, aneurysmal wall shear stress decreased with increasing number of deployed stents. Conclusion This is the first study analyzing flow modifications associated with placement of Enterprise stents for aneurysm occlusion. Placement of two to three stents significantly reduced intraaneurysmal hemodynamic activities, thereby increasing the likelihood of inducing aneurysm thrombotic occlusion.