NUS Graduate School for Integrative Sciences and Engineering, National University of Singapore, Singapore, Singapore.
Department of Biomedical Engineering, National University of Singapore, Singapore, Singapore.
Biomech Model Mechanobiol. 2020 Dec;19(6):2643-2656. doi: 10.1007/s10237-020-01361-0. Epub 2020 Jul 3.
Aortic dissection (AD) is one of the most catastrophic cardiovascular diseases. AD occurs when a layer inside the aorta is disrupted and gives rise to the formation of a true lumen and a false lumen. These lumens can be connected through tears in the intimal flap which are known as entries. Despite being known for about two centuries, the effects of many factors on the morbidity and mortality of this disease are still unknown. As the blood interaction with the aorta is crucial in the severity and the progression of the aortic dissection, a biomechanical approach is chosen to investigate the influence of different morphologies on the severity of this disease. Using the finite element method (FEM) and the fluid-structure interaction (FSI) approach, we have evaluated the blood flow characteristics along the diseased aorta, in conjunction with the deformation of the aortic wall. In this study, an idealized geometry of a dissected descending aorta (type B) with two entries has been studied. The values for the diameter of the entry tear were chosen to be 5 mm and 10 mm. Therefore, a total of four conditions were investigated. According to our results, the retrograde flow through the proximal tear is dependent on the size of the distal re-entry and vice versa. Our results revealed that when both entry and re-entry tears are 10 mm in diameter, the flow passes through the true and false lumens with smaller resistance, resulting in a smaller flutter of the intimal flap, and therefore more stable intimal flap. Major oscillation frequencies of 2.5 Hz and 7.4 Hz were observed for the oscillation of the intimal flap, and amplitudes of the waves with higher frequencies were negligible.
主动脉夹层（AD）是最具灾难性的心血管疾病之一。当主动脉内部的一层破裂时，会形成真腔和假腔，从而导致 AD 的发生。这些腔室可以通过内膜瓣的撕裂（称为入口）相连。尽管这种疾病已经被认识了大约两个世纪，但许多因素对其发病率和死亡率的影响仍然未知。由于血液与主动脉的相互作用对主动脉夹层的严重程度和进展至关重要，因此选择了生物力学方法来研究不同形态对这种疾病严重程度的影响。我们使用有限元方法（FEM）和流固耦合（FSI）方法，评估了沿病变主动脉的血流特性，同时考虑了主动脉壁的变形。在这项研究中，研究了具有两个入口的理想化 B 型降主动脉夹层的几何形状。入口撕裂的直径值分别选为 5 毫米和 10 毫米。因此，总共研究了四种情况。根据我们的结果，近端撕裂处的逆行血流取决于远端再入口的大小，反之亦然。我们的结果表明，当入口和再入口撕裂的直径均为 10 毫米时，血流通过真腔和假腔的阻力较小，导致内膜瓣的颤动较小，因此内膜瓣更稳定。内膜瓣的主要振荡频率为 2.5 Hz 和 7.4 Hz，并且较高频率的波的幅度可以忽略不计。
