多重裸支架治疗腹主动脉瘤的血流动力学数值和实验研究

Abdominal aortic aneurysm (AAA) is one of diseases which risk the lives of old people. Multilayer stent technology isolates AAA and meanwhile keeps the blood flow in branch artery unobstructed through placing multiple overlapping stents. Thus, it is used in the treatment of complicated AAA. However, the multilayer stent with too high or too low mesh density either contributes to the obstruction of blood flow in branches, or cannot isolate the blood completely or quickly reduce the pressure in AAA, which could cause the continued expansion or even rupture of AAA. Consequently, the mesh density of multilayer stent plays a vital role in isolating AAA and maintaining unimpeded blood flow in branch artery. This project focuses on the hemodynamics of AAA after implantation of the multilayer stent. At first, clinical trials would provide data for developing the multi-scale numerical model. Secondly, an in vitro experimental platform will be established on the basis of clinical data and numerical simulation results. Then, animal experiments will be conducted to investigate and verify the effects of the mesh density on AAA treatment and blood flow. Moreover, a mathematical model will be developed in accordance with the relationship among mesh density, the morphology/size of AAA and the diameter of the branch vessel. And the effects of mesh density on the treatment of AAA will be presented further. In conclusion, our study could offer the theoretical basis for the reasonable selection of the multilayer stent and design optimization of mesh density, and it has important scientific and clinical significances for improving AAA treatment.

腹主动脉瘤是一种严重威胁老年人生命的疾病。多层裸支架技术通过放置多层网状支架结构，在隔绝动脉瘤的同时保持分支动脉通畅，常被用于复杂腹主动脉瘤的治疗。但过密或过疏的多层裸支架要么阻塞分支动脉的血流，要么不能完全隔绝血液并迅速降低瘤腔压力，使瘤腔有继续扩大甚至破裂的风险，因此合理的支架网格密度在隔绝瘤体并保持分支血管通畅起着至关重要的作用。为此，本项目围绕多层裸支架植入后的血流动力学问题，首先，通过临床检测收集多尺度数值模型所需的数据，其次，利用临床数据和数值模拟结果构建体外实验平台，然后，通过动物实验分析和验证网格密度对血液输运和动脉瘤治疗的影响，此外，还将利用网格密度与瘤体形态、瘤体大小、分支血管直径之间的关系，建立数学模型，进一步揭示网格密度对腹主动脉瘤治疗的影响。综上，本课题将对多层裸支架的合理选型及网格密度的优化设计提供理论依据，对改进腹主动脉瘤治疗具有重要的科学和临床意义。

腹主动脉瘤是一种严重威胁老年人生命的疾病。多层裸支架技术通过放置多层网状支架结构，在隔绝动脉瘤的同时保持分支动脉通畅，常被用于复杂腹主动脉瘤的治疗。但过密或过疏的多层裸支架要么阻塞分支动脉的血流，要么不能完全隔绝血液并迅速降低瘤腔压力，使瘤腔有继续扩大甚至破裂的风险，因此合理的支架网格密度在隔绝瘤体并保持分支血管通畅起着至关重要的作用。本项目围绕多层裸支架在治疗腹主动脉瘤的血流动力学问题，重点展开以下研究：（1）多种胸腹动脉瘤形态学研究，建立动脉瘤理想模型及通过3D打印完成模型制作；（2）为后续数值模拟的基础，突破了3-4层支架的叠加建模和计算网格划分的障碍，建立多层裸支架植入动脉瘤的计算模型；（3）建立一整套体外测试系统，既能用于腹主动脉瘤的体外实验，也能用于下肢的肌肉灌注实验，该测试系统对研究动脉瘤在不同大小和形态下的血流动力学变化规律，验证了数值模拟的精确性；（4）首次提出氧气传输模型，并以此为基础计算多层裸支架植入后的低氧低壁面切应力区域，比较了低氧和低壁面切应力的作用，得到在血栓化中低切应力占主导地位的结论；（5）研究覆膜支架和多层裸支架的安放顺序，解释了临床中使用双支架组合方案的合理性；（6）研究多层裸支架的覆盖率，解释了为什么临床需要植入多层的效果；（7）对临床常见的多达四层的裸支架非定常数值模拟，得到支架越密越有利于动脉瘤的隔绝，进而促进动脉瘤内的血栓化，继而有助于防止动脉瘤破裂甚至使其萎缩的结论；（8）对不同偏心程度动脉瘤的研究，发现多层裸支架对非偏心动脉瘤的隔绝效果更好；（9）设计编织型多层裸支架，完成新西兰兔腹主动脉的动脉瘤造模，所造动脉瘤完全支架植入的标准；通过本项目的研究结果，力图探寻多层裸支架植入对腹主动脉瘤的治疗效果及血流动力学影响，为阐明腹主动脉瘤发生和发展机制、多层裸支架和覆膜支架临床治疗效果，为胸腹动脉瘤的临床支架植入提供理论指导。