Sukavaneshvar S, Rosa G M, Solen K A
Department of Chemical Engineering, Brigham Young University, Provo, UT 84602, USA.
Ann Biomed Eng. 2000 Feb;28(2):182-93. doi: 10.1114/1.243.
In vitro stent-induced thromboembolism was altered by the presence of residual stenoses placed upstream or placed upstream and downstream of the stent. Heparinized (3 micro/ml) bovine blood was gravity fed through a conduit with a deployed coronary stent. Embolism was continuously monitored using a light-scattering microemboli detector, and the thrombus accumulated on the stent at the conclusion of the experiment was assessed gravimetrically. Gaussian stenoses (75% reduction in the cross-sectional area) were placed upstream or upstream and downstream of the stent to alter flow characteristics in the stent region. The presence of stenoses enhanced embolization from the stent in all cases, while end-point thrombus accumulation on the stent decreased with only an upstream stenosis present, and increased when upstream and downstream stenoses were present. Computational fluid dynamics with and without hypothetical model thrombi were used to ascertain the alterations in the flow environment caused by the stenoses and thrombi. Combining the computed hemodynamic parameters with experimental results indicated that increased radial transport of blood components and low wall shear stress provided by the stenoses and thrombi may explain the enhancement of end-point thrombus accumulation. Analysis further showed that thrombi growing at the stenosis-induced reattachment and separation points will be subjected to high shear forces which may explain the increased embolism when stenoses are present.
体外支架诱导的血栓栓塞会因在支架上游或支架上下游放置残余狭窄而发生改变。将肝素化（3微克/毫升）的牛血通过带有已展开冠状动脉支架的导管进行重力灌注。使用光散射微栓子探测器持续监测栓塞情况，并在实验结束时通过重量法评估积聚在支架上的血栓。在支架上游或支架上下游放置高斯狭窄（横截面积减少75%）以改变支架区域的血流特性。在所有情况下，狭窄的存在都会增强支架的栓塞，而仅存在上游狭窄时，支架上的终点血栓积聚减少，当存在上下游狭窄时则增加。使用有和没有假设模型血栓的计算流体动力学来确定由狭窄和血栓引起的血流环境变化。将计算得到的血流动力学参数与实验结果相结合表明，狭窄和血栓所提供的血液成分径向运输增加以及低壁面剪应力可能解释了终点血栓积聚的增强。分析进一步表明，在狭窄诱导的再附着和分离点处生长的血栓将受到高剪切力作用，这可能解释了存在狭窄时栓塞增加的原因。
