Schuster P R, Wagner J W
U.S. Food and Drug Administration, Division of Mechanics and Materials Science, Rockville, Maryland 20852.
J Biomed Mater Res. 1989 Feb;23(2):207-22. doi: 10.1002/jbm.820230206.
Bioprosthetic heart valves are being used more often because of certain advantages they have over artificial valves. The bioprostheses are less thrombogenic, cause a lower incidence of hemolysis, and usually fail in a slow progressive manner. A combination of flow characterization and accelerated testing was used to assess the durability of two types of pericardial valves, the Ionescu-Shiley Low Profile Mitral and the Carpentier-Edwards Low Profile Aortic valve. The flow characterization work was done in an aortic chamber designed for in vivo simulation. The function of the valve was monitored between different stages of the accelerated testing using laser Doppler anemometry. Accelerated testing was performed at 1300 cardiac cycles per minute, and physiologic conditions both in closing pressures and the ambient temperature were maintained. Results indicated a change in flow characteristics owing to cyclic loading of the leaflet tissue. The flow orifice increased over time leading to a decrease in peak velocity. Future developments in Doppler ultrasound may facilitate non-invasive assessment of these peak velocity variations. Calcification of the tissue was not considered, since this was an in vitro study.
生物人工心脏瓣膜因其相对于人工瓣膜具有某些优势而被更频繁地使用。生物人工瓣膜的血栓形成性较低，溶血发生率较低，并且通常以缓慢渐进的方式失效。采用流动特性表征和加速测试相结合的方法来评估两种心包瓣膜（Ionescu-Shiley 低剖面二尖瓣和 Carpentier-Edwards 低剖面主动脉瓣）的耐久性。流动特性表征工作在一个设计用于体内模拟的主动脉腔室中进行。在加速测试的不同阶段之间，使用激光多普勒测速仪监测瓣膜的功能。加速测试在每分钟 1300 个心动周期下进行，并维持关闭压力和环境温度方面的生理条件。结果表明，由于瓣叶组织的循环加载，流动特性发生了变化。流动孔口随时间增加，导致峰值速度降低。多普勒超声的未来发展可能有助于对这些峰值速度变化进行非侵入性评估。由于这是一项体外研究，未考虑组织的钙化情况。
