Development of nitinol-based stent-graft for the treatment of aortic aneurysms : with special reference to a thin and flexible stent-graft system.

本研究的目的是开发一种薄且柔性的覆膜支架系统，其均匀附着于整个主动脉壁。根据我们以前的实验研究，我们构建了一种新型的镍钛合金网状支架，该支架由一根镍钛合金（0.30mm金属丝，直径20- 30 mm支架中每根金属丝之间的距离为4- 5 mm）金属丝覆盖薄聚酯膜（0.1mm厚，孔隙率500-1000，编织型）制成。对该覆膜支架进行了体内检查，通过强度和振动试验，其耐受性良好（径向力几乎与Z支架相同，在振动试验中观察到金属丝轻微腐蚀，与8年以上的心跳计数相当）。离体犬主动脉检查显示主动脉通畅，分支阻断。经过这些基本的测试，这种新型的覆膜支架在严格的知情同意后被用于无法手术的主动脉瘤急诊病例。截至2001年3月，应用该系统治疗了约30例难以治愈的主动脉瘤急诊病例。未观察到明确的系统相关并发症。这种柔性覆膜支架系统与迂曲的动脉吻合良好。约90%的病例最终排除了主动脉瘤。目前正在对这些案件作进一步评估。此外，该系统在体内和动物中的基本评价也正在进行，以进一步改进该系统和开发更先进的系统。

The purpose of this study was to develop a thin and flexible stent-graft system with homogeneous attachment to the entire aortic wall. According to our previous experimental study, we constructed a new type of nitinol based mesh type stent made of one nitinol (0.30mm wire, distances between each wires was 4-5mm in 20-30mm diameter stent) wire covered with thin polyester membrane (0.1mm thickness, porosity 500-1000, woven type). This stent-graft was examined in vivo and it was well tolerated by strength and vibration tests (almost the same radial force as that of Z stent, slight erosion of the wires was seen in vibration test comparable to more than 8 years heart beats counts). In vitro examination in aorta of the dogs revealed good patency of the aorta and blockade of its branches. After these basic tests, this new type of stent- graft was used for the inoperable emergent cases of aortic aneurysms after intense informed consent. Until March 2001, around 30 cases of inonerable emergent cases of aortic aneurysm were treated by this system. No definite system-related complications were seen. This flexible stent-graft system well fitted the tortuous aortas. Final exclusion of the aortic aneurysm was seen around 90% of cases. Further evaluation of these cases is now undergoing. In addition, the basic evaluation of this system in vivo and in animals is also being performed for further improvement of this system and for the development of more advanced system.