EVALUATION OF BIOPROSTHETIC CARDIAC VALVE FAILURE IN AN ANIMAL MODEL

本课题的目的是建立生物假体的动物模型 心脏瓣膜衰竭，并利用该动物模型系统来评估 病理改变和血流动力学功能障碍， 阀门。 我们已经证明，在青少年中植入生物瓣膜 绵羊表现出相同的变性病理变化， 与植入人体的钙化物一样， 与人类相比，这些变化在绵羊中加速。 近 来自10个国家的600枚猪主动脉或牛心包生物瓣膜 将不同的源植入动物模型系统中以评估 病理变化的特征，比较变化 在不同类型的瓣膜中，比较 植入二尖瓣与三尖瓣位置的瓣膜， 评价植入前接受处理的瓣膜， 以消除钙化过程。 由于这些类型的 观察，临床试验已经开始与一种新型的 生物瓣膜 同样重要的，如果不是更多，至少有五个 已经从临床使用的考虑中拒绝了一些类型的瓣膜。 该模型还用于验证超声波技术， 包括彩色编码的二维多普勒，用于表征 生物、机械和合成瓣叶瓣膜速度/流量 轮廓和瓣膜故障的非侵入性检测。

The purpose of this project is to develop an animal model of bioprosthetic cardiac valve failure and to utilize this animal model system to evaluate the pathologic alterations and hemodynamic dysfunction which develops in the valves. We have shown that bioprosthetic valves implanted in juvenile sheep demonstrate the same pathologic alterations of degeneration and calcification as those implanted in humans; however, the development of these alterations is accelerated in sheep as compared to humans. Nearly 600 porcine aortic or bovine pericardial bioprosthetic valves from ten different sources have been implanted in the animal model system to assess the characteristics of the pathologic changes, to compare the alterations in different types of valves, to compare the alterations occurring in valves implanted in the mitral versus the tricuspid positions, and to evaluate valves treated prior to implantation with processes to retard or to eliminate the calcification process. Due to these types of observations, clinical trials have been initiated with one new type of bioprosthetic valve. Equally important, if not more so, at least five types of valves have been rejected from consideration for clinical use. The model additionally being utilized to validate ultrasonic techniques, including color-encoded 2-D Doppler, for the characterization of bioprosthetic, mechanical, and synthetic leaflet valve velocity/flow profiles and for the noninvasive detection of valve failure.