Swirling Flow Can Suppress Flow Disturbances in Endovascular Stents: A Numerical Study

To test the hypothesis that by intentionally inducing swirling flow in an endovascular stent, hemodynamic performance of the stent can be improved, we numerically analyzed the flow characteristics in a simplified model of a stent within a straight segment of an artery in which swirling flow was introduced intentionally. The study was designed with two purposes: 1) to investigate whether swirling flow is beneficial to suppress flow disturbance in the stent; and 2) to determine the minimum helical strength of the swirling flow required in the design of a swirling flow stent. The numerical simulation showed that the swirling flow indeed reduced the size of the disturbed flow zones, enhanced the average wall shear stress, and lowered oscillatory shear index in the stent, which have been believed to be adverse factors involved in the development of arterial restenosis after stent deployment. The minimum inlet helicity density (or strength) of the swirling flow required was approximately 6.5 m/s(2). Based on the study, it is also believed that a stent with a structure that possesses intrinsic characteristics to automatically induce swirling flow in the stent is better than a stent with a front swirling flow inducer in terms of hemodynamics. ASAIO Journal 2009; 55:543-549.