Thrombus Deposition on Surface Modified Flow Diverting Stents in A Novel Bifurcation Blood Flow Loop Model

BACKGROUND AND PURPOSE: Blood flow loop (BFL) models offer controlled and customizable environments to simulate the dynamic conditions of blood circulation. Historically, these evaluations of flow diverting stents have consisted of a simple single lumen model. This study is the first of its kind to compare surface modified flow diverters deployed distal to a bifurcation in a BFL model and is supported through additional data generated from a thrombin-antithrombin (TAT) assay. MATERIALS AND METHODS: Test articles were deployed distal to a bifurcation, designed to present a more challenging environment for platelet activation than the traditional Chandler loop. Test articles included the following devices: Surpass Elite® with BioStealth™ Surface, Surpass Elite without BioStealth Surface, and Pipeline™ devices with Shield Technology™. Adhered platelet count, thrombus coverage scoring, flow rate at test termination, optical and scanning electron microscopy images, and TAT concentration were collected for each device type. RESULTS: The bifurcated blood flow loop model enabled differentiation between device types. Compared to the Unmodified surface, the BioStealth surface had a lower adhered platelet count, lower average thrombus coverage scores, and higher flow rate at test termination across six bovine donors, and a lower TAT concentration in human blood. The BioStealth Surface had no immature thrombus accumulation when viewed under SEM compared to the other studied surfaces. CONCLUSIONS: In an evaluation utilizing the novel bifurcated BFL model, Surpass Elite with BioStealth Surface demonstrated significantly lower adhered platelet count when compared to the Unmodified surface and statistically equivalent adhered platelet count to Shield. The TAT assay with human blood produced similar trends. The implications of these findings should be investigated through future in vitro and in vivo studies.