Key Laboratory of Ocean Energy Utilization and Energy Conservation of Ministry of Education, Dalian University of Technology, Dalian, 116024, China.
Department of Anesthesiology, The First Affiliated Hospital of Dalian Medical University, Dalian, 116011, China.
Comput Biol Med. 2017 Oct 1;89:236-247. doi: 10.1016/j.compbiomed.2017.07.029. Epub 2017 Aug 1.
Although the incidence of many cardiovascular diseases has declined as medical treatments have improved, the prevalence of aortic dissection (AD) has increased. Compared to type B dissections, type A dissections are more severe, and most patients with type A dissections require surgical treatment. The objective of this study was to investigate the relationships between the wall shear stress (WSS) on the aortic endothelium and the frequent tearing positions using computational fluid dynamics. Five type A dissection cases and two normal aortas were included in the study. First, the structures of the aortas before the type A dissection were reconstructed on the basis of the original imaging data. Analyses of flow in the reconstructed premorbid structures reveals that the rupture positions in three of the five cases corresponded to the area of maximum elevated WSS. Moreover, the WSS at the junction of the aortic arch and descending aorta was found to be elevated, which is considered to be related to the locally disturbed helical flow. Meanwhile, the highest WSS in the patients with premorbid AD was found to be almost double that of the control group. Due to the noticeable morphological differences between the AD cases and the control group, the WSSs in the premorbid structures without vasodilation in the ascending part were estimated. The computational results revealed that the WSS was lower in the aorta without vasodilation, but the pressure drop in this situation was higher than that with vasodilation in the ascending aorta. Significant differences were seen between the AD cases and the control group in the angles of the side branches of the aortic arch and its bending degree. Dilation of the ascending aorta and alterations in the branching angles may be the key determinants of a high WSS that leads to type A dissection. Greater tortuosity of the aortic arch leads to stronger helical flow through the distal aortic arch, which may be related to tears in this region.
虽然随着医疗水平的提高，许多心血管疾病的发病率有所下降，但主动脉夹层（AD）的患病率却有所上升。与 B 型夹层相比，A型夹层更为严重，大多数 A 型夹层患者需要手术治疗。本研究旨在使用计算流体动力学研究主动脉内皮壁面切应力（WSS）与频繁撕裂部位之间的关系。本研究纳入了 5 例 A 型夹层病例和 2 例正常主动脉。首先，基于原始影像学数据对 A 型夹层前的主动脉结构进行重建。分析重建的前病变结构中的血流发现，5 例病例中的 3 例破裂部位与最大升高的 WSS 区域相对应。此外，还发现主动脉弓和降主动脉交界处的 WSS 升高，这被认为与局部螺旋流紊乱有关。同时，患有前病变 AD 的患者的最高 WSS 几乎是对照组的两倍。由于 AD 病例和对照组之间存在明显的形态差异，因此估计了升主动脉无扩张时前病变结构中的 WSS。计算结果表明，无扩张的主动脉中的 WSS 较低，但在这种情况下，升主动脉的扩张会导致压力下降，比无扩张时更高。AD 病例与对照组在主动脉弓侧支的角度及其弯曲程度方面存在显著差异。升主动脉扩张和分支角度的改变可能是导致 A 型夹层的高 WSS 的关键决定因素。主动脉弓的迂曲程度越大，通过远端主动脉弓的螺旋流越强，这可能与该区域的撕裂有关。
