Woo Y R, Yoganathan A P
Life Support Syst. 1985 Oct-Dec;3(4):283-312.
A two-dimensional laser Doppler anemometer system was used to study the velocity and turbulent shear stress fields created by various types of mechanical aortic heart valve prostheses under physiological pulsatile flow conditions. The prosthetic valves studied were the Starr-Edwards caged ball valve, Bjork-Shiley tilting disc valve, Medtronic-Hall tilting disc valve, and St. Jude bileaflet valve. The results indicate that all four prosthetic valve designs studied create very disturbed flow fields with regions of flow separation and/or stagnation and regions of elevated turbulent shear stress. The maximum values of the mean turbulent shear stresses measured during peak systole were 1200 dynes/cm2 for the Starr-Edwards valve, 1600 dynes/cm2 for the Bjork-Shiley valve, 1000 dynes/cm2 for the Medtronic-Hall valve, and 1050 dynes/cm2 for the St. Jude valve. The corresponding values during the deceleration phase were about 800, 600, 450 and 800 dynes/cm2, respectively. These elevated turbulent shear stresses could cause sublethal and/or lethal damage to blood elements, and, together with the regions of flow separation and/or stagnation, could lead to thrombus formation and/or tissue overgrowth on the valve structure, as observed on the clinically recovered prosthetic valves.
采用二维激光多普勒风速仪系统，研究了各种类型的机械主动脉心脏瓣膜假体在生理脉动流条件下所产生的速度场和湍流剪应力场。所研究的人工瓣膜有斯塔尔-爱德华兹笼球瓣、比约克-希利倾斜盘瓣、美敦力-霍尔倾斜盘瓣和圣犹达双叶瓣。结果表明，所研究的所有四种人工瓣膜设计都会产生非常紊乱的流场，存在流动分离和/或停滞区域以及湍流剪应力升高的区域。在收缩期峰值期间测得的平均湍流剪应力最大值，斯塔尔-爱德华兹瓣膜为1200达因/平方厘米，比约克-希利瓣膜为1600达因/平方厘米，美敦力-霍尔瓣膜为1000达因/平方厘米，圣犹达瓣膜为1050达因/平方厘米。减速期的相应值分别约为800、600、450和800达因/平方厘米。这些升高的湍流剪应力可能会对血液成分造成亚致死和/或致死性损伤，并且，与流动分离和/或停滞区域一起，可能会导致瓣膜结构上形成血栓和/或组织过度生长，这在临床回收的人工瓣膜上已观察到。
