Vortex shedding as a mechanism for free emboli formation in mechanical heart valves
Vortex shedding as a mechanism for free emboli formation in mechanical heart valves
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DOI：
10.1115/1.429634
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发表时间：
2000-04-01
影响因子：
1.7
通讯作者：
Gharib, M
中科院分区：
文献类型：
--
作者：
Bluestein, D;Rambod, E;Gharib, M
机械心脏瓣膜（MHV）血栓栓塞并发症的高发生率限制了其作为永久性植入物的成功。所有MHV的致血栓性主要是由于与异物表面接触和非生理性流动模式引起的血小板活化。后者包括由瓣膜设计特征引起的升高的流动应力和血液再循环区域。采用Wilcox k-omega湍流模型对双叶MHV内部低雷诺数流动进行了非定常湍流数值模拟，并与采用数字粒子图像测速仪（DPIV）的脉冲复制系统进行的定量流动可视化进行了比较。在减速阶段，瓣叶的尾流显示了相互作用的脱落涡流的复杂模式。颗粒路径显示，暴露于瓣叶周围最高流动应力的血小板被截留在脱落涡流中。潜在活化的这种血小板可能倾向于聚集并形成游离栓子。一旦形成，这种游离栓塞将通过脱落的体积对流到下游，增加全身栓塞的风险。【S0148-0731（00）01202-4】。
The high incidence of thromboembolic complications of mechanical heart valves (MHV) limits their success as permanent implants. The thrombogenicity of all MHV is primarily due to platelet activation by contact with foreign surfaces and by nonphysiological flow patterns. The latter include elevated flow stresses and regions of recirculation of blood that are induced by valve design characteristics. A numerical simulation of unsteady turbulent flow through a bileaflet MHV was conducted, using the Wilcox k-omega turbulence model for internal low-Reynolds-number flows, and compared to quantitative flow visualization performed in a pulse duplicator system using Digital Particle Image Velocimetry (DPIV). The wake of the valve leaflet during the deceleration phase revealed an intricate pattern of interacting shed vortices. Particle paths showed that platelets that were exposed to the highest flow stresses around the leaflets were entrapped within the shed vortices. Potentially activated such platelets may tend to aggregate and form free emboli. Once formed, such free emboli would be convected downstream by the shed vol tices, increasing the risk of systemic emboli. [S0148-0731(00)01202-4].