Manning Keefe B, Kini Vinayak, Fontaine Arnold A, Deutsch Steven, Tarbell John M
Department of Bioengineering, The Pennsylvania State University, University Park, PA 16802, USA.
Artif Organs. 2003 Sep;27(9):840-6. doi: 10.1046/j.1525-1594.2003.07194.x.
The regurgitant flow fields of clinically used mechanical heart valves have been traditionally studied in vitro using flow visualization, ultrasound techniques, and laser Doppler velocimetry under steady and pulsatile flow. Detailed investigation of the forward and regurgitant flow fields of these valves can elucidate a valve's propensity for blood element damage, thrombus formation, or cavitation. Advances in particle image velocimetry (PIV) have allowed its use in the study of the flow fields of prosthetic valves. Unlike other flow field diagnostic systems, recent work using PIV has been able to relate particular regurgitant flow field characteristics of the Bjork-Shiley Monostrut valve to a propensity for cavitation. In this study, the regurgitant flow field of the St. Jude Medical bileaflet mechanical heart valve was assessed using PIV under physiologic pulsatile flow conditions. Data collected at selected time points prior to and after valve closure demonstrated the typical regurgitant jet flow patterns associated with the St. Jude valve, and indicated the formation of a strong regurgitant jet, in the B-datum plane, along with twin vortices near the leaflets. Estimated ensemble-average viscous shear rates suggested little potential for hemolysis when the hinge jets collided. However, the vortex motion near the occluder tips potentially provides a low-pressure environment for cavitation.
传统上，临床上使用的机械心脏瓣膜的反流流场是在体外通过流动可视化、超声技术以及在稳定和脉动流条件下的激光多普勒测速法进行研究的。对这些瓣膜的正向和反流流场进行详细研究可以阐明瓣膜对血液成分损伤、血栓形成或空化的倾向。粒子图像测速技术（PIV）的进展使其能够用于人工心脏瓣膜流场的研究。与其他流场诊断系统不同，最近使用PIV的研究已经能够将比约克-希利单支柱瓣膜的特定反流流场特征与空化倾向联系起来。在本研究中，在生理脉动流条件下使用PIV评估了圣犹达医疗双叶机械心脏瓣膜的反流流场。在瓣膜关闭前后的选定时间点收集的数据显示了与圣犹达瓣膜相关的典型反流射流流动模式，并表明在B基准平面形成了强烈的反流射流，以及小叶附近的双涡旋。估计的总体平均粘性剪切率表明，当铰链射流碰撞时，溶血的可能性很小。然而，封堵器尖端附近的涡旋运动可能为空化提供一个低压环境。
