Wall Shear Stress Directional Abnormalities in BAV Aortas: Toward a New Hemodynamic Predictor of Aortopathy?
Wall Shear Stress Directional Abnormalities in BAV Aortas: Toward a New Hemodynamic Predictor of Aortopathy?
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DOI：
10.3389/fphys.2018.00993
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发表时间：
2018
影响因子：
4
通讯作者：
Sucosky P
中科院分区：
文献类型：
--
作者：
Liu J;Shar JA;Sucosky P
二叶式主动脉瓣（BAV）在升主动脉（AA）中产生壁面剪切应力（WSS）异常，这可能是BAV患者中动脉病高患病率的原因。虽然以前的研究已经分析了BAV AA中的总WSS或流向WSS的幅度和振荡特性，但缺乏对周向分量的评估，尽管其在这种高度螺旋流环境中具有预期的意义。这一差距可能阻碍了BAV动脉病变的稳健血流动力学预测因素的识别。本研究的目的是对BAV AA中的WSS幅度、振荡和方向特性进行全局和特定组件评估。使用我们先前的瓣膜-主动脉流体-结构相互作用（FSI）模型，在三尖瓣主动脉瓣（TAV）和BAV AA的近端和中间凸面中计算WSS环境。特定的WSS特征进行了研究的时间切变幅度（TSM）和振荡切变指数（OSI）。WSS方向性通过平均WSS矢量幅度和角度以及角分散指数（Dα）进行量化。当地WSS震级和多方向性被记录在一个新的剪切震级和方向性指数（SMDI）中，该指数计算为平均WSS震级和Dα的乘积。BAV使AA承受周向TSM过载（与TAV相比增加2.4倍）。TAV和BAV AA表现出单向周向WSS（OSI < 0.04），近端（OSI > 0.21）和中间（OSI < 0.07）部分之间的单向纵向WSS逐渐增加。BAV生成的平均WSS向量偏向前壁，WSS角分布显示近端AA的均匀性降低（Dα与TAV相比增加0.27个点）。所有BAV AA中的SMDI均升高，但在近端LR-BAV AA（相对于TAV增加3.6倍）和中间RN-BAV AA（相对于TAV增加1.6倍）中达到峰值。该分析证明了周向WSS分量的重要性以及BAV AA中存在大量WSS方向异常。BAV AA中的SMDI异常分布遵循BAV AA中扩张的形态型依赖性发生，表明该指标对BAV动脉病变的预测潜力。
The bicuspid aortic valve (BAV) generates wall shear stress (WSS) abnormalities in the ascending aorta (AA) that may be responsible for the high prevalence of aortopathy in BAV patients. While previous studies have analyzed the magnitude and oscillatory characteristics of the total or streamwise WSS in BAV AAs, the assessment of the circumferential component is lacking despite its expected significance in this highly helical flow environment. This gap may have hampered the identification of a robust hemodynamic predictor of BAV aortopathy. The objective of this study was to perform a global and component-specific assessment of WSS magnitude, oscillatory and directional characteristics in BAV AAs. The WSS environments were computed in the proximal and middle convexity of tricuspid aortic valve (TAV) and BAV AAs using our previous valve-aorta fluid-structure interaction (FSI) models. Component-specific WSS characteristics were investigated in terms of temporal shear magnitude (TSM) and oscillatory shear index (OSI). WSS directionality was quantified in terms of mean WSS vector magnitude and angle, and angular dispersion index (Dα). Local WSS magnitude and multidirectionality were captured in a new shear magnitude and directionality index (SMDI) calculated as the product of the mean WSS magnitude and Dα. BAVs subjected the AA to circumferential TSM overloads (2.4-fold increase vs. TAV). TAV and BAV AAs exhibited a unidirectional circumferential WSS (OSI < 0.04) and an increasingly unidirectional longitudinal WSS between the proximal (OSI > 0.21) and middle (OSI < 0.07) sections. BAVs generated mean WSS vectors skewed toward the anterior wall and WSS angular distributions exhibiting decreased uniformity in the proximal AA (0.27-point increase in Dα vs. TAV). SMDI was elevated in all BAV AAs but peaked in the proximal LR-BAV AA (3.6-fold increase vs. TAV) and in the middle RN-BAV AA (1.6-fold increase vs. TAV). This analysis demonstrates the significance of the circumferential WSS component and the existence of substantial WSS directional abnormalities in BAV AAs. SMDI abnormality distributions in BAV AAs follow the morphotype-dependent occurrence of dilation in BAV AAs, suggesting the predictive potential of this metric for BAV aortopathy.
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影响因子：
37.8
作者：
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通讯作者：
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