主动脉瓣口血流速度空间分布形成机理研究

目的： 通过动物试验探讨主动脉瓣口血流速度空间分布的形成机理。方法： 研究对象包括１０ 只猪， 在全麻下实施开胸手术暴露心脏， 并获得左室流出道长轴切面， 使其长轴平行于超声声束方向。研究内容包括： １） 利用彩色多普勒血流成像测量主动脉瓣口血流速度空间分布扭曲程度； ２） 观察左室流出道中轴线两侧彩色血流的对称性， 判断血流会聚状态； ３） 根据二维图像测量室间隔角度。然后观察在整个射血期内上述三个指标的动态变化。结果： 主动脉瓣口血流速度空间分布状态随左室流出道内血流会聚方式变化而变化。在射血早期， 左室流出道内血流会聚方式最不对称， 大部分血流沿室间隔及左室前壁流向主动脉瓣口。相应地， 主动脉瓣口血流速度分布的扭曲程度最大， 且最大流速紧靠室间隔及左室前壁。射血中、晚期，左室流出道内血流逐渐变为呈中轴对称性地进入主动脉瓣口，此时主动脉瓣口血流速度分布变为平坦对称。然而， 从左室射血早期到中、晚期， 室间隔角度却逐渐增大。结论： 左室流出道内的血流会聚方式是决定主动脉瓣口血流速度空间分布的最重要因素。

The Mechanisms Responsible for the Spatial Flow Velocity Distribution in Aortic Annulus

Objective:To explore the mechanisms responsible for the aortic annulus(AA) skewed spatial velocity distribution.Methods:Ten open chest normal pigs' AA cross sectional velocity profiles were constructed by using Doppler color flow mapping.The patterns of flow convergence in the left ventricular outflow tract(LVOT) were quantified by measuring the color flow areas on the anterior and posterior sides of the central axis of the AA and their differences were calculated.The dynamic changes of the velocity profile in AA,the flow convergence pattern in the LVOT and the septal angle throughout systole were all scrutinized.Results:The velocity profile in the AA pursued the flow convergence pattern in the LVOT.During early systole,the flow convergence pattern was mostly asymmetrical,the main part of the converging flow got along the anterior wall of the LVOT,consequently,the velocity profile was mostly skewed during early systole with highest velocity along the anterior wall.Towards late systole,the flow convergence pattern became more and more symmetrical,and the velocity profile in the AA gradually became flattened.To the contrary,the septal angle slightly increased throughout systole.Conclusion:The pattern of flow convergence in the LVOT is a major determinant for the velocity distribution in the AA.