EVALUATIONS OF PROSTHETIC CARDIAC VALVES--IN VIVO STUDIES

该项目的研究是正在进行的开发， 使用青少年的体内原位动物模型系统的应用 用于评估心脏瓣膜和心血管血流动力学的绵羊。 前几年的研究集中在传统的水力和 正常心脏瓣膜和人工心脏瓣膜血流动力学评价 瓣膜替代品，以及形态和物理特征， 生物瓣膜钙化变性。 目前的努力强调 心内血流动力学的研究，用于量化病理生理学 两个自体血管的狭窄性和非狭窄性病变发生的异常 和人工心脏瓣膜。 在过去的一年里， 二尖瓣返流的实验制剂和两种类型的 二尖瓣狭窄的实验制备已经使用 彩色多普勒血流图技术。 二尖瓣返流动物 由于瓣叶穿孔或腱索断裂， 研究了确定洗脱剂流量和洗脱剂分数。 由于二尖瓣环收缩或由于 对钙化生物瓣进行研究，以确定狭窄口 面积和二尖瓣血流。 这些研究表明：（1） 用动量连续性原理观测收敛流 保存可用于评价心内血流动力学 病理生理学;和2）空间（几何）和 时间（脉动）特性在应用基本 流体力学的物理理论与心脏的复杂性 瓣膜血流动力学 这些研究探讨了方法论， 原则，并证明这些非侵入性的有效性和实用性 获得临床相关定量信息的技术。

The studies of this project are those of the ongoing development and applications of an in vivo, in situ animal model system using juvenile sheep for evaluating cardiac valves and cardiovascular flow dynamics. Previous years' studies have concentrated upon conventional hydraulic and hemodynamic evaluations of normal cardiac valves and prosthetic cardiac valvular substitutes, and upon morphologic and physical characterization of calcific degeneration of bioprosthetic valves. Current efforts emphasize studies of intracardiac flow dynamics for quantifying the pathophysiologic abnormalities occuring with stenotic and regurgitant lesions of both native and prosthetic cardiac valves. During the past year two types of experimental preparations of mitral regurgitation and two types of experimental preparations of mitral stenosis have been investigated using color Doppler flow mapping technology. Animals with mitral regurgitation due to perforated leaflets or due to disrupted chordae tendineae were studied to determine regurgitant flow volume and regurgitant fraction. Animals with mitral stenosis due to mitral annular constriction or due to calcified bioprosthetic valves were studied to determining stenotic orifice area and transmitral flow. These studies demonstrate: 1) that observations of convergent flow using principles of momentum continuity preservation may be used to evaluate intracardiac hemodynamic pathophysiology; and 2) that clarification of both spatial (geometric) and temporal (pulsatile) characteristics are important in applying fundamental physical theories of fluid mechanics to the complexities of cardiac valvular flow dynamics. The studies explore methodology, illustrate principles, and demonstrate the validity and utility of these non invasive techniques for obtaining clinically relevant quantitative information.