Laboratoire de Biomécanique Appliquée, Aix-Marseille Université, IFSTTAR, LBA, UMR T24, 51 Bd. P. Dramard, 13015, Marseille, France.
Aix-Marseille Université, CNRS, CRMBM, UMR 7339, Marseille, France.
Biomed Eng Online. 2019 Feb 26;18(1):19. doi: 10.1186/s12938-019-0632-7.
The axial motion of aortic root (AR) due to ventricular traction was previously suggested to contribute to ascending aorta (AA) dissection by increasing its longitudinal stress, but AR in-plane motion effects on stresses have never been studied. The objective is to investigate the contribution of AR in-plane motion to AA stress levels.
The AR in-plane motion was assessed on magnetic resonance imagining data from 25 healthy volunteers as the movement of the AA section centroid. The measured movement was prescribed to the proximal AA end of an aortic finite element model to investigate its influences on aortic stresses. The finite element model was developed from a patient-specific geometry using LS-DYNA solver and validated against the aortic distensibility. Fluid-structure interaction (FSI) approach was also used to simulate blood hydrodynamic effects on aortic dilation and stresses.
The AR in-plane motion was 5.5 ± 1.7 mm with the components of 3.1 ± 1.5 mm along the direction of proximal descending aorta (PDA) to AA centroid and 3.0 ± 1.3 mm perpendicularly under the PDA reference system. The AR axial motion elevated the longitudinal stress of proximal AA by 40% while the corresponding increase due to in-plane motion was always below 5%. The stresses at proximal AA resulted approximately 7% less in FSI simulation with blood flow.
The AR in-plane motion was comparable with the magnitude of axial motion. Neither axial nor in-plane motion could directly lead to AA dissection. It is necessary to consider the heterogeneous pressures related to blood hydrodynamics when studying aortic wall stress levels.
先前有研究认为，由于心室牵引导致主动脉根部（AR）的轴向运动通过增加升主动脉（AA）的纵向应力而有助于升主动脉夹层，但 AR 的面内运动对应力的影响从未被研究过。本研究旨在探讨 AR 的面内运动对 AA 应力水平的贡献。
从 25 名健康志愿者的磁共振成像数据中评估 AR 的面内运动，作为 AA 节段质心的运动。将测量的运动施加到主动脉有限元模型的近端 AA 端，以研究其对主动脉应力的影响。该有限元模型是使用 LS-DYNA 求解器从患者特定的几何形状开发的，并针对主动脉可扩张性进行了验证。还使用流固耦合（FSI）方法来模拟血流动力学对主动脉扩张和应力的影响。
AR 的面内运动为 5.5±1.7mm，其中沿近端降主动脉（PDA）至 AA 质心方向的分量为 3.1±1.5mm，垂直于 PDA 参考系的分量为 3.0±1.3mm。AR 的轴向运动使近端 AA 的纵向应力升高了 40%，而面内运动对应的升高始终低于 5%。在考虑血流的 FSI 模拟中，近端 AA 的应力降低了约 7%。
AR 的面内运动与轴向运动的幅度相当。轴向和面内运动都不能直接导致 AA 夹层。在研究主动脉壁应力水平时，有必要考虑与血液动力学相关的不均匀压力。
