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而灵活的支架移植物系统，均匀附着于整个主动脉壁。根据我们之前的实验研究，我们构建了一种新型的镍钛诺基网状支架，由一根镍钛诺（0.30mm丝，20-30mm直径支架中每根丝之间的距离为4-5mm）丝覆盖薄聚酯膜（厚度0.1mm，孔隙率500-1000，编织型）。这种支架移植物在体内进行了检查，强度和振动测试对其耐受性良好（与Z支架几乎相同的径向力，振动测试中观察到轻微的导线侵蚀，可与8年以上的心跳次数相媲美）。犬主动脉体外检查显示主动脉通畅良好，分支阻滞。经过这些基本的测试，这种新型的支架-移植物被用于在强烈知情同意后不能手术的急诊主动脉瘤病例。截至2001年3月，约有30例无法忍受的急诊主动脉瘤患者接受了该系统的治疗。未见明确的系统相关并发症。这种灵活的支架移植系统很好地适应了弯曲的主动脉。大约90%的病例最终排除了主动脉瘤。目前正在对这些病例进行进一步评价。此外，为了进一步完善该系统，开发更先进的系统，也正在对该系统进行体内和动物试验的基本评估。

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.