School of Chemistry, Physics and Mechanical Engineering, Queensland University of Technology, Brisbane, 4000, Australia.
Deformation Control Lab, Hokkaido University, Sapporo, Hokkaido, 060-8628, Japan.
Biomech Model Mechanobiol. 2020 Feb;19(1):7-20. doi: 10.1007/s10237-019-01191-9. Epub 2019 Jul 10.
Plaque rupture is related to the mechanical stress it suffered. The value and distribution of the mechanical stress in plaque could help on assessing plaque vulnerability. To look into the stress conditions in the coronary artery, a patient-specific coronary model was created by using optical coherence tomography (OCT) and angiography imaging data. The reconstructed coronary model consisted of the structure of the lumen, the arterial wall and plaque components. Benefited by the high resolution of OCT, detailed structures such as the thin fibrous cap could be observed and built into the geometry. On this reconstructed coronary model, a fully coupled fluid-structure interaction (FSI) simulation was performed. The principle stress in coronary plaque and the wall shear stress (WSS) were analyzed. The FSI simulation results show that the cap thickness had a significant effect on the stress, and the principle stress at the thin cap area was more than double of those at the locations with a larger thickness. WSS is thought as an important parameter to assess the potentially dangerous areas of the atherosclerosis-prone (caused by low WSS) and the plaque rupture (high WSS). From the WSS plots of our FSI model, the area with abnormal WSS value was detected around the position where a lipid core existed. The FSI simulation results were compared with the results from the conventional structure-only and the computational fluid dynamics (CFD)-only computational models to quantify the difference between the three models. We found little difference in the principle stress results between the FSI and the structure-only model, but a significant difference between the FSI and the CFD-only model when looking into the WSS. The WSS values at the two observation spots from the CFD-only model were higher than the values from the FSI model by 17.95% and 22.66% in average, respectively. Furthermore, the FSI model detected more areas of low WSS, because the fluid domain could expand circumferentially when pressure loaded on the flexible arterial. This study suggests that OCT-based FSI model may be useful for plaque vulnerability assessment and it may be critical to perform the FSI simulation if an accurate WSS value is required.
斑块破裂与它所承受的机械应力有关。斑块中的机械应力的大小和分布有助于评估斑块的脆弱性。为了研究冠状动脉中的应力状况，使用光学相干断层扫描（OCT）和血管造影成像数据创建了一个患者特定的冠状动脉模型。重建的冠状动脉模型由管腔、动脉壁和斑块成分的结构组成。得益于 OCT 的高分辨率，可以观察到并构建详细结构，如薄纤维帽。在这个重建的冠状动脉模型上，进行了完全耦合的流固耦合（FSI）模拟。分析了冠状动脉斑块中的主应力和壁面切应力（WSS）。FSI 模拟结果表明，帽厚度对应力有显著影响，薄帽区域的主应力是厚度较大区域的两倍以上。WSS 被认为是评估易发生动脉粥样硬化（由于低 WSS 导致）和斑块破裂（高 WSS）的潜在危险区域的重要参数。从我们的 FSI 模型的 WSS 图中，可以检测到脂质核心位置周围存在异常 WSS 值的区域。将 FSI 模拟结果与传统的仅结构模型和计算流体动力学（CFD）仅计算模型的结果进行比较，以量化这三种模型之间的差异。我们发现，在主应力结果方面，FSI 与仅结构模型之间几乎没有差异，但在 WSS 方面，FSI 与 CFD 仅模型之间存在显著差异。在 CFD 仅模型中，从两个观察点获得的 WSS 值比 FSI 模型高 17.95%和 22.66%。此外，FSI 模型检测到更多低 WSS 区域，因为当压力施加在柔性动脉上时，流体域可以沿圆周方向扩展。这项研究表明，基于 OCT 的 FSI 模型可能有助于评估斑块的脆弱性，如果需要准确的 WSS 值，则进行 FSI 模拟可能至关重要。
