Enhancement of stent-induced thromboembolism by residual stenoses: Contribution of hemodynamics

In vitro stent-induced thromboembolism was altered by the presence of resid ual stenoses placed upstream ol placed upstream and downstream of the stent . Heparinized (3 mu/ml) bovine blood was gravity fed through a conduit with a deployed coronary stent. Embolism was continuously monitored using a lig ht-scattering microemboli detector, and the thrombus accumulated on the ste nt at the conclusion of the experiment was assessed gravimetrically. Gaussi an stenoses (75% reduction in the cross-sectional area) were placed upstrea m or upstream and downstream of the stent to alter flow characteristics in the stent region. The presence of stenoses enhanced embolization from the s tent in all cases, while end-point thrombus accumulation on the stent decre ased with only an upstream stenosis present, and increased when upstream an d downstream stenoses were present. Computational fluid dynamics with and w ithout hypothetical model thrombi were used to ascertain the alterations in the flow environment caused by the stenoses and thrombi. Combining the com puted hemodynamic parameters with experimental results indicated that incre ased radial transport of blood components and low wall shear stress provide d by the stenoses and thrombi may explain the enhancement of end-point thro mbus accumulation. Analysis further showed that thrombi growing at the sten osis-induced reattachment and separation points will be subjected to high s hear forces which may explain the increased embolism when stenoses are pres ent. (C) 2000 Biomedical Engineering Society. [S0090-6964(00)00602-0].