EVALUATIONS OF PROSTHETIC CARDIAC VALVES--IN VIVO STUDIES

本项目的研究是对正在进行的开发和 幼体活体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。 前几年的研究主要集中在常规液压和 正常心脏瓣膜和人工心脏的血流动力学评价 瓣膜替代物，并根据形态和物理特征 生物瓣膜钙化变性。目前的努力强调 心内血流动力学定量评价心脏病理生理的研究 两个民族的狭窄和反流性病变都出现了异常 和人工心脏瓣膜。在过去的一年里，两种类型的 二尖瓣关闭不全与两种类型二尖瓣关闭不全的实验准备 对二尖瓣狭窄的实验准备进行了研究。 彩色多普勒血流图技术。二尖瓣关闭不全动物 由于小叶穿孔或肌腱索断裂， 对返流流量和返流分数的测定进行了研究。 二尖瓣环缩窄致二尖瓣狭窄动物 钙化生物瓣膜用于确定狭窄瓣口。 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 保存方法可用于评价心内血流动力学 病理生理学；以及2)对空间(几何)和 时间(脉动)特性在应用基本特性时很重要 心脏复杂性的流体力学物理理论 瓣膜流动动力学。研究探索了方法论，说明了 原理，并证明了这些非侵入性的有效性和实用性 获取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.