1.School of Life Science, Beijing Institute of Technology;2.Department of Vascular and Endovascular Surgery, Chinese PLA General Hospital
The National Basic Research Program of China (973 Program),The National Natural Science Foundation of China (General Program, Key Program, Major Research Plan)
目的 结合形态学分析与计算流体力学方法(computational fluid dynamics, CFD),探索Stanford B型主动脉夹层病发机理,为有效预测B型主动脉夹层发生提供依据。方法 对6例初发夹层患者(夹层组)的CTA数据和6例正常志愿者(对照组)的MR黑血成像数据进行图像分割和三维重建,获得个体化的主动脉三维模型。使用压缩算法去除假腔,获得夹层病发前主动脉形态,与对照组进行对比。结果 研究发现,与对照组相比,夹层组主动脉弓降交界处的截面积呈现明显增大(892.03±263.78mm2 vs 523.67±64.10mm2, p=0.036) ；左锁骨下动脉和主动脉之间的夹角明显减小(66.62±20.11 vs 100.40±15.35, p=0.036)；主动脉弯曲度显著增加(0.37±0.07 vs 0.21±0.51, p=0.011) ；通过模拟血液流动,可以发现夹层组的平均壁面剪切力(Average Wall Shear Stress, AWSS) 明显高于对照组；发生夹层区域的血液呈现低速漩涡流动状态；且夹层区域的震荡剪切指数(Oscillating Shear Index, OSI) 也明显升高。结论 研究结果可用于指导临床B型主动脉夹层病发初期诊疗决策。
Objective The objective of this study is to use computational fluid dynamics (CFD) numerical simulation method to compare geometric and hemodynamic parameters between the cases suffering from primary dissection and the normal cases, providing evidence for the pathogenesis and prediction of Type-B aortic dissection. Methods The study includes six primary Type-B dissection cases scanned by CT and six normal cases applied to MRI. Then patient-specific three-dimensional models of aorta were established through image segmentation and 3-D reconstruction. The pre-Type-B dissection aortas were constructed by applying the scaling algorithm to shrink the dissection. We compared the differences between morphological parameters and hemodynamic parameters of the two groups. Results Compared with the normal cases, the area of the descending aorta increases dramatically in the dissection group (892.03±263.78mm2 vs 523.67±64.10mm2, p=0.036); significant drop in the angle of the left subclavian artery occurred(66.62±20.11vs100.40±15.35, p=0.036); the tortuosity of the aorta also has an obvious increase(0.37±0.07vs0.21±0.51, p=0.011). If somewhere in the aorta shows higher average wall shear stress (AWSS); the velocity is not uniform and the value of the Oscillating Shear Index (OSI) is higher, Type-B aortic dissection is more likely to occur in this area. Conclusions Obvious changes in anatomical (larger area of the descending aorta; smaller angle of the left subclavian artery;more tortuous aorta)and flow related parameters(higher average wall shear stress; unsteady flow; higer Oscillating Shear Index) for the aorta subjected to dissection, providing guidance for the clinical practice.