中文摘要：

目的探讨可回收Niti记忆合金支架在犬气管狭窄模型中置入及回收后的影像和病理变化。方法 16只实验犬,在DSA引导下经口在气管内置入裸支架制作气管狭窄模型,裸支架置入3个月内。选取狭窄程度为50%~60%的实验犬,再同法置入覆膜支架扩张狭窄气管,研究覆膜支架置入后影像学动态变化,后于4、6、8、10、12、14周随机抽取2只实验犬进行覆膜支架回收,处死实验犬,对支架和留置段气管进行病理分析,了解气管壁粘膜黏膜增生和损伤情况,对支架留置和回收的时限进行评估。结果实验犬均于裸支架置入后2周左右出现喘鸣渐加重,3个月内共有12只实验犬气管狭窄程度符合进一步实验要求,2只实验犬死亡（感染1只,窒息1只）,2只实验犬气管狭窄程度低于预定标准;置入覆膜支架后实验犬呼吸困难症状减轻,DSA-3 D测量气管狭窄程度明显减轻,差异有统计学意义（t=48.407,P〈0.05）;第4周~第10周支架回收容易,回收支架表面光滑,支架内无明显组织增生及痰液潴留,其中第4周~第8周支架回收后气管狭窄处出现一定弹性回缩,第10周气管支架回收后无明显弹性回缩;第12周支架回收较为困难,支架与气管壁贴合较为紧密,回收支架表面残留片状气管内壁组织,病理提示为肉芽组织增生;第14周支架回收困难,1例回收未成功,1例回收过程中出现严重出血,且实验犬躁动明显。结论应用裸支架支架建立犬气管狭窄模型具有较强的可行性;可回收覆膜支架治疗实验犬良性气管狭窄效果明显,支架置入后10周左右为较佳回收时段,10周后随时间的推移回收难度相应增加。

英文摘要：

Objective To explore the changes in imaging and pathology after the implantation and retrieval of nickel-titanium shape memory alloy stent in a tracheal stricture canine model. Methods Tracheal stricture model were established by endotracheal implantation with bare stent in 16 dogs under the guidance of DSA. The polyurethane covered stents were placed in experimental dogs （the degree of stenosis is 50%-60% in three months. Observe the imaging features and changes of each experimental dog. At the time of 4 weeks, 6 weeks, 8 weeks, 10 weeks, 12 weeks and 14 weeks after stent placement, two dogs were randomly selected to remove the polyurethane covered stents and sacrificed to observe the pathological changes. And evaluated the time limite of stent placement and recovery. Results About 2 weeks after the bare metal stent placement, the dogs were wheezing and aggravated gradually. A total of 12 tracheal stricture canine models were successfully established in three months. 2 of 16 dogs died （1 infection, 1 asphyxia）, 2 of 16 dogs＇ degree of tracheal stenosis is lower than the predetermined criteria.The experimental dogs had dyspnea remission after the treatment of polyurethane covered stents implantation, and the extent of tracheal stenosis significantly reduced monitored by DSA- 3 D（t--48.407, P〈0.05）. It was easy to retrieve the polyurethane covered stents without obvious hyperplasia and obstruction of secretion like sputum during the 4-10 weeks. The elastic recoil happened in 4 week to 8 weeks, and vanished gradually after 10 weeks. About 12 weeks, stent-related granuloma formation had been developed excessively, and the recovery of stents became progressively more difficult. In 14 weeks, the recoveries were so difficult that 1 failed and 1 severe hemorrhage complication and the dogs were restlessness. Conclusion Application bare metal stents to dogs tracheal stenosis model is a stable and reproductive method; retrievable nickl-titanium shape memery aUory stent is very effective for the treatment of b