一种新型胸主动脉覆膜支架的设计与工艺研究
发布时间：2018-12-12 03:02
【摘要】：胸主动脉瘤是常见的扩张性主动脉高危疾病。随着医疗技术的发展,主动脉腔内修复技术(EVAR)已成为治疗胸主动脉瘤的首选治疗方案,而腔内修复术的关键在于人工血管系统的研制。人工血管系统主要包括覆膜支架和输送系统,覆膜支架的选择在一定程度上影响了治疗效果。现阶段国内在覆膜支架的结构设计及加工制作方面的研究明显不足,临床运用的覆膜支架大部分依靠进口,价格昂贵。覆膜支架分为支架和覆膜材料,支架多为基于NiTi合金超弹性设计的自膨胀式支架。但目前关于支架定型工艺的资料比较少,如何调整合金相变温度和组织状态,使支架在体温下具有良好的超弹性是本论文的重点。 对患者主动脉的MRI扫描图像进行图像分割及三维重建,通过实体造型及快速成型技术得到胸主动脉瘤模型。根据胸主动脉模型,利用脱模铸造法制作胸主动脉人工血管模型。利用人工血管模型搭建体外模拟循环装置,对覆膜支架进行体外模拟循环和流体实验。 本文研究利用短时连续热处理工艺来加工NiTi合金支架单元,研究热处理工艺条件对NiTi合金相变点的影响,利用NiTi合金应力-应变曲线评价NiTi合金超弹性特性,研究模具热惰性对支架定型处理的影响,确定了支架单元的定型工艺。选用支架的定型工艺为两步连续热处理：400℃,30min处理后,放入定型模具中,550℃定型处理15min,支架单元定型效果和力学性能最佳,具有优异的超弹性。 利用DSC测试支架单元相变温度为10℃,支架单元在体温下处于奥氏体状态,能够发生自膨胀,具有良好的超弹性。利用电子万能试验机测试支架单元的支撑力,主体支架单元的径向支撑力为3-5N,迷你环支架单元和顶端喇叭口支架单元的径向支撑力为2-3N。对血管壁有适宜的径向支撑力。 根据胸主动脉模型设计了一种新型覆膜支架。选用涤纶作为覆膜材料与定型后的支架单元缝合,缝制覆膜支架。支架为渐细的弯曲覆膜支架,顶端设有迷你环及喇叭口支架单元,弯曲支架的内侧设有加强筋。支架设计更加符合胸主动脉的生理结构,便于放入输送器中,保证支架对于弯曲的胸主动脉具有良好的贴壁性,支架支撑力良好。
[Abstract]:Thoracic aortic aneurysm is a common high risk disease of dilated aorta. With the development of medical technology, (EVAR) has become the first choice in the treatment of thoracic aortic aneurysm, and the key of endovascular repair is the development of artificial vascular system. The artificial vascular system mainly includes covered stent and delivery system, and the choice of covered stent affects the therapeutic effect to a certain extent. At present, the domestic research on the structure design and fabrication of membrane covered stent is obviously insufficient, most of the clinical application of membrane covered stent rely on import, and the price is expensive. The scaffolds are mainly self-expandable ones based on NiTi alloy super-elastic design. However, there is little information about the scaffold shaping process at present. How to adjust the phase transition temperature and the microstructure of the alloy to make the scaffold have good superelasticity at body temperature is the focus of this thesis. The thoracic aortic aneurysm model was obtained by solid modeling and rapid prototyping by segmenting and reconstructing the MRI images of the aorta. According to the model of thoracic aorta, the model of thoracic aortic prosthesis was made by the method of demoulding casting. The artificial vascular model was used to set up an extracorporeal circulation device to simulate the extracorporeal circulation and fluid flow of the coated scaffold. In this paper, the short-time continuous heat treatment process is used to process the NiTi alloy support unit. The influence of the heat treatment conditions on the transformation point of the NiTi alloy is studied. The stress-strain curves of the NiTi alloy are used to evaluate the superelastic properties of the NiTi alloy. The influence of mould thermal inertia on the setting treatment of the bracket was studied, and the setting process of the support unit was determined. The setting process of the support is two-step continuous heat treatment: 400 鈩，
本文编号：2373776
[Abstract]:Thoracic aortic aneurysm is a common high risk disease of dilated aorta. With the development of medical technology, (EVAR) has become the first choice in the treatment of thoracic aortic aneurysm, and the key of endovascular repair is the development of artificial vascular system. The artificial vascular system mainly includes covered stent and delivery system, and the choice of covered stent affects the therapeutic effect to a certain extent. At present, the domestic research on the structure design and fabrication of membrane covered stent is obviously insufficient, most of the clinical application of membrane covered stent rely on import, and the price is expensive. The scaffolds are mainly self-expandable ones based on NiTi alloy super-elastic design. However, there is little information about the scaffold shaping process at present. How to adjust the phase transition temperature and the microstructure of the alloy to make the scaffold have good superelasticity at body temperature is the focus of this thesis. The thoracic aortic aneurysm model was obtained by solid modeling and rapid prototyping by segmenting and reconstructing the MRI images of the aorta. According to the model of thoracic aorta, the model of thoracic aortic prosthesis was made by the method of demoulding casting. The artificial vascular model was used to set up an extracorporeal circulation device to simulate the extracorporeal circulation and fluid flow of the coated scaffold. In this paper, the short-time continuous heat treatment process is used to process the NiTi alloy support unit. The influence of the heat treatment conditions on the transformation point of the NiTi alloy is studied. The stress-strain curves of the NiTi alloy are used to evaluate the superelastic properties of the NiTi alloy. The influence of mould thermal inertia on the setting treatment of the bracket was studied, and the setting process of the support unit was determined. The setting process of the support is two-step continuous heat treatment: 400 鈩，
本文编号：2373776
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