Barclay S A, Eidenvall L, Karlsson M, Andersson G, Xiong C, Ask P, Loyd D, Wranne B
Department of Clinical Physiology, University of Linköping, Sweden.
J Am Soc Echocardiogr. 1993 Jul-Aug;6(4):433-45. doi: 10.1016/s0894-7317(14)80242-3.
The hemispheric proximal isovelocity surface area method for quantification of mitral regurgitant flow (i.e., Qc = 2 pi r2v), where 2 pi r2 is the surface area and v is the velocity at radius r, was investigated as distance from the orifice was increased. Computer simulations and steady flow model experiments were performed for orifices of 4, 6, and 8 mm. Flow rates derived from the centerline velocity and hemispheric assumption were compared with true flow rates. Proximal isovelocity surface area shape varied as distance from each orifice was increased and could only be approximated from the hemispheric equation when a certain distance was exceeded: > 7, > 10, and > 12 mm for the 4, 6, and 8 mm orifices, respectively. Prediction of relative error showed that the best radial zone at which to make measurements was 5 to 9, 6 to 14 and 7 to 17 mm for the 4, 6, and 8 mm orifices, respectively. Although effects of a nonhemispheric shape could be compensated for by use of a correction factor, a radius of 8 to 9 mm can be recommended without the use of a correction factor over all orifices studied if a deviation in calculated as compared with true flow of 15% is considered acceptable. These measurements therefore have implications for the technique in clinical practice.
研究了用于量化二尖瓣反流流量的半球近端等速表面积法（即Qc = 2πr²v，其中2πr²为表面积，v为半径r处的速度）随距瓣口距离增加的变化情况。针对4毫米、6毫米和8毫米的瓣口进行了计算机模拟和稳流模型实验。将根据中心线速度和半球假设得出的流量与实际流量进行比较。随着距每个瓣口距离的增加，近端等速表面积形状会发生变化，只有当超过一定距离时，才能用半球方程近似：4毫米、6毫米和8毫米瓣口分别为> 7毫米、> 10毫米和> 12毫米。相对误差预测表明，4毫米、6毫米和8毫米瓣口进行测量的最佳径向区域分别为5至9毫米、6至14毫米和7至17毫米。虽然非半球形状的影响可以通过使用校正因子来补偿，但如果将计算流量与实际流量的偏差15%视为可接受，那么对于所有研究的瓣口，可不使用校正因子而推荐8至9毫米的半径。因此，这些测量结果对临床实践中的该技术具有重要意义。
