高分辨C臂CT对镁合金支架治疗巴马小型猪颈动脉狭窄体内降解情况动态观察可行性探讨

Dynamic observation of degradation property of novel magnesium alloy stents in Bama mini-pig models of carotid artery stenosis by high-resolution C-arm CT:a feasibility study

目的:探讨高分辨C臂CT动态观察可降解镁合金支架治疗巴马小猪颈动脉狭窄后体内降解情况的可行性。方法:以12头巴马小猪为研究对象,通过大球囊过度扩张+高脂高盐配方饲料喂养方式建立巴马小猪颈动脉狭窄模型。造模24周后采用DSA造影证实颈动脉狭窄模型建立并采用球囊扩张的方式置入自制编织型可降解镁合金支架。术后即刻和术后第30、60、90天根据DSA造影评价支架置入后血管通畅情况及再狭窄情况;术后第30、60、90天分别处死4头实验猪,根据支架置入区域高分辨C臂CT扫描结果及狭窄处标本染色结果观察镁合金支架降解情况并总结支架降解过程中影像学特点。结果:12头巴马小猪颈动脉狭窄模型建立后成功置入12枚编织型可降解镁合金支架,技术成功率100%。术后即刻及术后各时间点DSA均显示小猪血管管腔通畅,未见明显狭窄。高分辨C臂CT扫描和病理学检查显示支架置入30 d时支架整体轮廓清晰,支架编织丝及网孔可辨,支架轻度降解;置入60 d时支架轮廓模糊,部分金属丝断裂,网孔部分可见,支架部分降解;置入90 d时支架整体轮廓模糊或不可辨,未见金属丝和网孔,支架几乎全部降解。结论:可降解镁合金支架在巴马小猪颈动脉内90 d时几乎完全降解,高分辨C臂CT可动态监测其体内降解情况。

Objective To explore the degradation property of novel magnesium alloy stents in Bama mini-pig models of carotid artery stenosis,and evaluate the feasibility of observing their dynamic and continuous process by high-resolution C-arm CT.Methods Twelve Bama mini-pigs were selected;carotid artery stenosis models were established by large balloon over-dilation and high-fat and high-salt diet in Bama pigs;24 weeks after that,self-made braided degradable magnesium alloy stents were inserted into the carotid artery stenosis models(confirmed by DSA)by balloon dilation.Degrees of stent patency and in-stent restenosis were examined by DSA immediately after procedure and on the 30th,60th and 90th d of procedure.Four experimental pigs were sacrificed on the 30th,60th and 90th d of procedure,respectively;the degradation property of the novel magnesium alloy stents was observed according to results of high-resolution C-arm CT in the inserted-stent areas and staining results of specimens in the stenosis areas,and stent imaging features during degradation were summarized.Results Twelve Bama mini-pig models of carotid artery stenosis were established and 12 magnesium alloy stents were successfully inserted with a technical success rate of 100%.Both immediate postoperative and follow-up angiography showed patency of the vascular lumens without obvious in-stent restenosis.High-resolution C-arm CT and pathological examination showed homogeneous stent lumens and clear delineation of the stent meshes,with slightly degraded stent on the 30th d of procedure;the stent lumen was blurred and some magnesium alloy wires were fractured with developed degradation of the stent on the 60th d of procedure;and the stent meshes and stent strut could not be visualized due to severe degradation of the stent on the 90th d of procedure.Conclusion Magnesium alloy degradable stent is almost completely degraded within 90th d of procedure in Bama mini-pig models of carotid artery stenosis,and high-resolution C-arm CT can be used to dynamically monitor the degradation of the stent in vivo.