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Abstract：
Supravalvular aortic stenosis (SVAS) is an aortic malformation characterized by a narrowing of the ascending aorta, resulting in abnormal hemodynamics and pressure drop across the stenosed region. It has been observed that the pressure drops measured from Doppler ultrasound exams often tend to be higher than those obtained from invasive cardiac catheterization. These misleadingly elevated pressure measurements may drive the decision to refer patients for surgical treatment prematurely. Considering this strong clinical association, the purpose of this work is to develop a computational modeling approach using a two-way coupled fluid-structure interaction methodology to determine an accurate prediction of trans-stenotic pressure drop and to further highlight the discrepancy between the SVAS assessment methods. Blood is modeled using Navier-Stokes equations while the aortic wall is simulated by a composite poroelastic structure to represent the three main layers of the arterial wall. The relationship between aortic wall elasticity and the blood flow conditions is examined in varying levels of stenosis, ranging from mild to severe degrees of vessel diameter narrowing. A substantial overestimation of the traditional Doppler pressure drop measurement is observed, especially for severe stenosis levels. The simulation results indicate that elasticity of the aortic wall has a relatively little effect on trans-stenotic pressure drop for the range of mild to moderate SVAS cases, but predicted to have a profound effect for severe SVAS cases. Moreover, significant sensitivity to the pressure drop across the SVAS region from stenosis severity is observed.
摘要：
主动脉瓣上狭窄(SVAS)是一种以升主动脉狭窄为特征的主动脉畸形,导致狭窄区域的异常血流动力学和压降。已经观察到,从多普勒超声检查测量的压降通常倾向于高于从侵入性心脏导管插入术获得的压降。这些错误的升高的压力测量值可能会促使决定过早地将患者转诊以进行手术治疗。考虑到这种强烈的临床关联，这项工作的目的是开发一种使用双向耦合流体-结构相互作用方法的计算建模方法，以确定跨狭窄压降的准确预测，并进一步强调SVAS评估方法之间的差异。使用Navier-Stokes方程对血液进行建模，而主动脉壁由复合多孔弹性结构模拟，以表示动脉壁的三个主要层。在不同程度的狭窄中检查主动脉壁弹性与血流状况之间的关系，范围从轻度到严重的血管直径变窄的程度。观察到对传统多普勒压降测量的大幅高估，特别是对于严重的狭窄水平。模拟结果表明，对于轻度至中度SVAS病例，主动脉壁弹性对经狭窄压降的影响相对较小。但预计对严重的SVAS病例有深远的影响。此外，观察到狭窄严重程度对SVAS区域压降的显著敏感性。
