调控支架构型预防围主动脉弓部夹层平行支架术后内漏的生物力学研究

Continued development of endovascular stent-grafts has permitted their use in the proximal descending aorta. Recently, attention has been focused on the aortic arch. Aortic arch dissections included the aortic dissections with entry tears locating in the distal ascending aorta, in the arch, or in the proximal descending aorta with retrograde extension of the dissection into the arch. Hybrid procedures were used to be the classic treatment, including various methods to disconnect the arch branch arteries and transpose them to neighboring arteries or revascularize with bypasses. Can we treat para-arch aortic dissections by pure endovascular procedure? So fenestration techniques and branched stent-graft appeared to be alternatives to conventional open and hybrid surgery for the treatment of aortic arch dissections. But they have requirements on the anatomy of the aortic arch and the aortic dissection. So parallel stent techniques (PST) have been proposed as a novel procedure, needing no customization, without special requirements on the anatomy, with encouraging early results..However, endoleak after PST, defined as persistent blood flow within the false lumen, constitutes treatment failure and one of the major reasons for postoperative imaging surveillance. Despite of its importance, investigation on how to prevent the endoleak after PST has been least carried out. Based on our previous study, change the key parameters of the configuration of the stent-graft may result in the different interactions among main stent, chimney stents and aortic wall..Therefore, the hypothesis of this study is that: the gutter between stents and aortic wall can be diminished by manipulating the stent configuration. And the biologic reaction of the local contacting aortic wall can also be ameliorated so as not to increase the risk of generating new aortic dissection. .This study will be conducted in three aspects: First, retrospectively analyze the clinical data of endoleak after the PST to sieve out the risk factors on aortic morphology, the strategies of PST and stent-graft configurations. Thus to determine the targets and strategies for following ex-vivo simulation and mechanical test. Second, accurately calculate and depict the space structure of the gutter in the proximal sealing zone induced by different stents combination. And we planned to analyze the hemodynamic status of the gutter through PIV experiments. And we would also do the ex-vivo mechanical analyses of stent-graft and aortic wall using strain gage technique. Through above ex-vivo tests, the modified stent configuration can be recognized. Third, use the modified stent-graft on the animal model, test and analyze the biomechanical effects on the aorta as a whole, as well as on the local artery tissue of different contact regions. Then, integrating these results into a “stent configuration — gutter space structure — hemodynamic status — aortic biological reaction” effect model, which will help to find out the mechanical and space structure effect of the stent configuration, and to identify the best strategy and configuration of stent-graft for aortic arch dissection..This study will provide important insight on the endoleak after parallel stent technique in the aortic arch. And it will be essential for optimizing the configuration of the stent-graft to preferably match the aortic dissection morphology. As biomechanical rationales of endovascular treatment of aortic dissection, the outcomes of this study may have great clinical potential.

围主动脉弓部夹层是腔内微创治疗难点，平行支架技术提供了一种适于各种弓部解剖、无需定制的新疗法。但内漏是其主要并发症，阻碍其推广应用，如何预防亟待研究。支架间及支架-主动脉管壁间隙是导致内漏的直接原因。我们前期研究表明：改变支架构型可影响“支架-支架-管壁”间的相互作用，从而减少间隙。进一步需要研究：如何判别内漏的不同预后？如何预防内漏的发生？本项目拟：①分析临床资料，筛选平行支架腔内隔绝术后不良内漏的危险因素和关键特征，提出优化的方案和支架构型；②通过体外模拟和力学测试，以三维空间、流场状态、相互间作用力作为主要指标，进一步优化筛选支架匹配方案和优化构型；③将优化构型的支架移植物应用于动物模型，分析其管壁生物学反应，进一步论证改进构型和匹配方案的支架移植物的生物学效应。本研究有助阐明平行支架腔内修复术后内漏的机制和调控方案，为进一步提高平行支架技术的临床效果提供科学的实验依据和应用指导。

围主动脉弓部夹层是腔内微创治疗难点，平行支架技术提供了一种适于各种弓部解剖、无需定制的新疗法。但内漏是其主要并发症，阻碍其推广应用，如何预防亟待研究。支架间及支架-主动脉管壁间隙是导致内漏的直接原因。主要研究内容：①分析临床资料，筛选平行支架腔内隔绝术后不良内漏的危险因素和关键特征，提出优化的方案和支架构型；②通过体外模拟和力学测试，以三维空间、流场状态、相互间作用力作为主要指标，进一步优化筛选支架匹配方案和优化构型；③将优化构型的支架移植物应用于动物模型，分析其管壁生物学反应，进一步论证改进构型和匹配方案的支架移植物的生物学效应。本项目从cTEVAR术后内漏并发症最根本的原因：支架与支架，支架与管壁的交互作用来开展研究，从不同部位主动脉弓部置入不同构型的主体支架，施加的力学影响→不同支架搭配的力学效应和空间位置关系→支架-支架-管壁三者之间的材料学匹配改变的不同层面，来探索差异化烟囱腔内隔绝术器具选用与cTEVAR术后并发症的相关关系；根据临床研究得出的危险因素和体外力学研究的结果，筛选出了优化的烟囱腔内隔绝术方案，观察其与前期结果相比能否降低cTEVAR术后并发症的风险，为进一步改进烟囱腔内隔绝术的临床效能、并提出专用的新型主体-烟囱支架构型，提供科学性的实验依据。经过本项目的系统生物力学对比分析后建立的烟囱腔内隔绝术后不良预后的风险评估模型，以及形成的专适于治疗主动脉弓部病变的腔内移植物，将大大提高主动脉弓部病变微创介入治疗的水平。