自膨式人工血管内支架对胸主动脉损伤的生物力学建模与数值仿真

Based upon a series of studies, our research team put stent-graft-induced mechanical injury forward as a hypothesis underlying the stent-graft-induced new entry (SINE) which was considered the first important fatal complication after the thoracic endovascular aortic repair (TEVAR) for Stranford type B aortic dissection. After a preliminary experiment supporting the hypothesis, we are applying for this project (1) to test the mechanical features of the human thoracic aorta and the self-expanding stent graft (SESG); (2) to conduct a preliminary numerical simulation of the thoracic aorta and the implanted SESG based upon the individual CT imaging and boundary conditions in 3 representative cases; (3) according to their respective aortic morphology and mechanical parameters, to customerize 3 aortic models with the silica gel and make a corresponding mechanical test, and to compare the analysis outcomes between the numerical and the physical models so as to acquire a reasonable conditions for the following experiment ; (4) and to select and group 60 post-TEVAR cases into 6 groups on the basis of their different SINE-related factors, and then conduct a numerical simulation of the thoracic aorta and the implanted SESG based upon their individual CT imaging and boundary conditions. The anticipated outcomes would contribute to (1) obtaining the mechanical features of the human thoracic aorta and the SESG; (2) showing the mechanical effects of the SESG on the thoracic aorta and the characters of their distribution, and providing the experimental evidence for the hypothesis of stent-graft-induced mechanical injury; (3) and offering a theoretical guidance for the improvement on the SESG design and the TEVAR planning, and thus hopefully reducing the incidence of SINE.

申请人前期研究发现了主动脉夹层胸主动脉腔内修复（TEVAR）术后严重并发症-支架源性新破口（SINE），并在大量临床观察的基础上提出了"支架源性力学损伤"的机制假说，但缺乏定量实验证据。本申请拟（1）测试胸主动脉与人工血管内支架（SESG）的力学性能参数；（2）基于临床采集的CT图像和边界条件，完成胸主动脉－SESG生物力学建模与数值仿真；（3）利用CT数据建立硅胶模型模拟体内真实环境，优化调试模型和仿真参数；（4）选择大样本TEVAR患者，基于个体化CT数据进行数值建模和仿真分析。以期获得胸主动脉与SESG之间的相互作用模式，尤其是后者造成力学损伤的原因、性质和特点，从而为"支架源性力学损伤"假说提供实验依据；对不同患者的具体情况，提供选择合适SESG，或优化SESG结构的依据，对已接受TEVAR治疗的患者分析发生SINE的可能性和预防措施，减少SINE的发生率，提高TEVAR的有效性。

申请人前期研究发现了主动脉夹层胸主动脉腔内修复（TEVAR）术后严重并发症-支架源性新破口（SINE），并提出了"支架源性力学损伤"的机制假说，但缺乏定量实验证据。本研究（1）通过采集猪胸主动脉标本进行力学测试，确定了可用于人主动脉标本的力学实验方法。之后分别获取人正常、主动脉瘤及主动脉夹层三类标本进行力学测试，得出了三者的弹性和血管壁抵抗局部垂直力破坏的能力依次减低的结论；而获取的力学参数也为后期本构模型的建立及数值仿真提供了基础条件。（2）分别使用HeartPrint™ Flex和传统有机玻璃材料建立主动脉模型并于其中置入人工血管内支架（SESG），发现HeartPrint™材料在重现正常人胸主动脉形态及模拟其力学性能两方面都明显优于传统模型，同时得出了支架对主动脉模型的压力主要集中于弓大弯侧左锁骨下动脉近端的结论。（3）通过对本中心收治的急性非复杂性Stanford B型夹层病人的胸腹主动脉计算机断层扫描血管造影（CTA）和医学数字成像和通信数据（DICOM）数据，结合前期实验结果建立本构模型，并通过ANSYS软件进行分析，发现原发破口对主动脉夹层假腔血流量率有显著影响，并可能进一步影响夹层的进展及预后；另外，根据该类患者的CTA及DICOM数据建立了主动脉夹层的数值模型，通过ADINA软件进行流固耦合模拟，探索了夹层真假腔内的应力特点；而将此模型通过ABAQUS进行有限元模拟，得出了支架置入后其应力的变化及主动脉壁不同部位的受力特点。基于个体化CT数据进行数值建模和仿真分析，可以在术前为术者提供选择合适SESG的依据，对已接受TEVAR治疗的患者，可协助分析其发生SINE的可能性和预防措施，减少SINE的发生率，提高TEVAR的有效性。（4）由于CTA不包含血流信息，因此我们在之前的实验基础上通过腔内超声和压力及流速导丝在TEVAR术中测得了真实的夹层病人的血流动力学数据。此外，我们通过获取病人的4D PC-MRI检查结果并分析，以无创的方法更加精确地取得了病人的血流动力学数据，为今后更好地预测主动脉夹层的病程及预后打下了基础。