Chen Zhuo, Zhou Yue, Wang Jingying, Liu Xiaowei, Ge Shuping, He Yihua
Department of Ultrasound, Beijing Anzhen Hospital, Capital Medical University, Beijing, China.
School of Aeronautic Sciences and Engineering, BEIHANG Unversity, Beijing, China.
Echocardiography. 2017 Dec;34(12):1858-1866. doi: 10.1111/echo.13644. Epub 2017 Aug 22.
We sought to develop a hemodynamic model of aortic and ductal arches using computational fluid dynamics (CFD) and 3D/4D spatio-temporal image correlation (STIC) fetal echocardiography and to investigate the hemodynamics of coarctation of aorta (CoA) in human fetuses using this approach.
We obtained 3D/4D STIC fetal echocardiographic images of the aortic and ductal arches (DA) in five normal fetuses. Based on these images, we simulated the hemodynamics in the two arches using CFD. Subsequently, we reduced the dimensions of aortic isthmus from 100% to 85%, 70%, 55%, 40%, and 25% of the original dimension digitally. Numerical simulation was repeated in each condition, and flow profile, velocity, pressure, and wall shear stress (WSS) were compared with those of the baseline normal aortic and ductal arches.
With the progressive narrowing in the aortic isthmus, there were alterations in the flow profile, velocity, pressure, and WSS. The downstream vortexes disappeared, and the double helix profile became single helix. When the aortic isthmus reduced by 55% in dimension, there was an exponential increase in velocity and WSS and decrease in pressure.
The aortic and ductal arch geometry and flow lead to the alterations in flow profile, velocity, pressure, and WSS in the aortic isthmus in normal and CoA models, which are conductive of ductal issue migration into these areas. A 55% reduction in the dimension of aortic isthmus is associated with exponential change in velocity, pressure, and WSS, a probable threshold for hemodynamically significant CoA.
我们试图利用计算流体动力学（CFD）和三维/四维时空图像相关（STIC）胎儿超声心动图技术建立主动脉弓和动脉导管弓的血流动力学模型，并使用该方法研究人类胎儿主动脉缩窄（CoA）的血流动力学。
我们获取了5例正常胎儿主动脉弓和动脉导管弓的三维/四维STIC胎儿超声心动图图像。基于这些图像，我们使用CFD模拟了两个弓的血流动力学。随后，我们将主动脉峡部的尺寸从原始尺寸的100%数字式地缩减至85%、70%、55%、40%和25%。在每种情况下重复进行数值模拟，并将血流剖面、速度、压力和壁面剪应力（WSS）与基线正常主动脉弓和动脉导管弓的相应参数进行比较。
随着主动脉峡部逐渐变窄，血流剖面、速度、压力和WSS均发生改变。下游涡流消失，双螺旋剖面变为单螺旋剖面。当主动脉峡部尺寸缩减55%时，速度和WSS呈指数增加，压力降低。
在正常和CoA模型中，主动脉弓和动脉导管弓的几何形状及血流导致主动脉峡部的血流剖面、速度、压力和WSS发生改变，这有利于动脉导管组织迁移至这些区域。主动脉峡部尺寸缩减55%与速度、压力和WSS的指数变化相关，这可能是血流动力学显著型CoA的一个阈值。
