Analysis of a coupled fluid-structure interaction model of the left atrium and mitral valve
Analysis of a coupled fluid-structure interaction model of the left atrium and mitral valve
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DOI：
10.1002/cnm.3254
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发表时间：
2019-11-01
影响因子：
2.1
通讯作者：
Luo, Xiaoyu
中科院分区：
文献类型：
--
作者：
Feng, Liuyang;Gao, Hao;Luo, Xiaoyu
我们提出了一个耦合的左心房二尖瓣模型的基础上，计算机断层扫描与纤维增强超弹性材料。流固耦合是通过浸入式边界有限元框架实现的。研究了病理条件（如二尖瓣返流和房颤）以及几何和结构变化（即均匀与非均匀心房壁厚度以及基于规则与基于图谱的纤维结构）对系统的影响。我们发现，在心房颤动的情况下，肺静脉血流逆转在晚期房颤消失，和左心耳口的充盈波在收缩期已减少幅度。在二尖瓣返流的情况下，可以看到更高的心房压力和紊乱的血流，特别是在收缩期，当可以发现大的反流性射流与抑制的肺静脉血流。我们还表明，基于规则和基于图谱的纤维定义方法导致类似的流场和心房壁变形。然而，壁厚从不均匀到均匀的变化往往低估了心房变形。使用均匀但加厚的壁也降低了整体应变水平。左心耳内的流速随着左心房壁的厚度而增加，这在心耳血栓形成方面是重要的。能量分析表明，左心房内的流动的动能和耗散能量被心房颤动和二尖瓣反流不同地改变，提供了一个有用的指示心房的性能在病理情况下。
We present a coupled left atrium-mitral valve model based on computed tomography scans with fibre-reinforced hyperelastic materials. Fluid-structure interaction is realised by using an immersed boundary-finite element framework. Effects of pathological conditions, eg, mitral valve regurgitation and atrial fibrillation, and geometric and structural variations, namely, uniform vs non-uniform atrial wall thickness and rule-based vs atlas-based fibre architectures, on the system are investigated. We show that in the case of atrial fibrillation, pulmonary venous flow reversal at late diastole disappears, and the filling waves at the left atrial appendage orifice during systole have reduced magnitude. In the case of mitral regurgitation, a higher atrial pressure and disturbed flows are seen, especially during systole, when a large regurgitant jet can be found with the suppressed pulmonary venous flow. We also show that both the rule-based and atlas-based fibre defining methods lead to similar flow fields and atrial wall deformations. However, the changes in wall thickness from non-uniform to uniform tend to underestimate the atrial deformation. Using a uniform but thickened wall also lowers the overall strain level. The flow velocity within the left atrial appendage, which is important in terms of appendage thrombosis, increases with the thickness of the left atrial wall. Energy analysis shows that the kinetic and dissipation energies of the flow within the left atrium are altered differently by atrial fibrillation and mitral valve regurgitation, providing a useful indication of the atrial performance in pathological situations.