CARDIOVASCULAR FLOW DYNAMICS--IN VIVO STUDIES

本年度在这一项目上的工作重点是研究 二维彩色血流显像心内血流动力学研究 多普勒超声定量病理生理血流动力学 异常 定量技术已应用于：1）二尖瓣 自体瓣膜返流，2）人工瓣膜狭窄病变 （3）小口径动脉和血管移植物狭窄病变。 在实验产生二尖瓣返流的动物中， 彩色多普勒血流数据分析证实了近端 用于非侵入性地定量抗肿瘤体积的加速度曲线 和不饱和馏分。 另一方面，在以下条件下进行的研究 类似的情况表明彩色喷射区的效用有限 用于评估二尖瓣返流严重程度的测量。 在 植入双叶人工二尖瓣的动物， 使用中心线加速度曲线的（空间导数）， 确定通过每个阀门的三个瞬时流速， 孔。 与狭窄相关的病理性血流紊乱 小口径动脉和血管移植物中的病变已经 表征了 这些研究表明：1）近端血流 利用动量连续性原理的收敛观测 保存可用于评价心内血流动力学 病理生理学;和2）自由射流通量的原理并不容易 适用于与心脏内异常低压相关的有界射流 钱伯斯 血管病变的定量研究已经开始。 这些基于基本物理原理的研究探索了 方法，说明原则，验证技术和演示 无创多普勒血流显像在临床上的应用 相关的量化信息。

The current year's efforts on this project have emphasized studies of intracardiac flow dynamics using flow imaging with two-dimensional color Doppler ultrasound for quantifying pathophysiologic hemodynamic abnormalities. Quantitative techniques have been applied to: 1) mitral regurgitation in native valves, 2) stenotic lesions in prosthetic valves and 3) stenotic lesions in small caliber arteries and vascular grafts. In animals with experimentally produced mitral regurgitation, digitally analyzed color Doppler flow data validated the use of proximal acceleration profiles for non invasively quantitating regurgitant volume and regurgitant fraction. On the other hand, studies performed under similar conditions demonstrated the limited utility of color jet area measurements for evaluating the severity of mitral regurgitation. In animals with bileaflet prosthetic mitral valves, the rate of change (spatial derivative) of the centerline acceleration profile was used to determine instantaneous flow rates through each of the valves' three orifices. the pathological flow disturbances associated with stenotic lesions in small caliber arteries and vascular grafts have been characterized. These studies demonstrate: 1) that proximal flow convergence observations using principles of momentum continuity preservation may be used to evaluate intracardiac hemodynamic pathophysiology; and 2) that principles of free jet flux are not readily applied to bounded jets associated with abnormal lows within cardiac chambers. Quantitative studies of vascular lesions have been initiated. these studies based on fundamental physical principles explore methodology, illustrate principles, validate techniques and demonstrate the utility of non invasive Doppler flow imaging to obtain clinically relevant quantitative information.