Department of Clinical Medicine, Faculty of Medicine, University of Bergen, N-5021 Bergen, Norway; Department of Orthopaedic Surgery, Haukeland University Hospital, N-5021 Bergen, Norway.
Department of Clinical Dentistry, Faculty of Medicine, University of Bergen, N-5009 Bergen, Norway.
J Mech Behav Biomed Mater. 2019 May;93:31-35. doi: 10.1016/j.jmbbm.2019.02.001. Epub 2019 Feb 4.
Intra-arterial stenosis due to atherosclerosis is often treated with endovascular balloon dilatation with a metal stent. Restenosis is common and is frequently treated with a new stent placed inside the existing one or the stents are placed with overlap to cover a larger area of the vessels. Observations of stent fractures, stent compression, accumulation of immunocompetent cells around stents have suggested the possibility of immunologic reactions to substances released from stents. An accelerated corrosion model was developed to study corrosion behaviour of commonly used surgical peripheral stents. Single nitinol stents (n = 6), connected stents of the same material (stent-in-stent, both nitinol, n = 7) and connected stents of dissimilar alloys (Nitinol with stainless steel stent inside, n = 7) were investigated. The stents were subjected to mechanical pulsatile radial strain (up to 8% strain at 1 Hz) and electrochemical stress (+112 mV vs. SCE). The release of nickel and titanium ions was compared. Scanning electron images were obtained. There was a higher release of nickel when combining two similar (range: 1382-8018 μg/L, p = 0.0012) and dissimilar (range: 170-2497 μg/L, p = 0.0023) stents compared to single stents (range: 0.4-216 μg/L). The concentration of titanium was low (range: 1.6-98.4 μg/L) with only a difference between the single and two similar stents (p = 0.0047). Deposits of corrosion products were clearly visible after fretting and pitting corrosion mainly on the Nitinol stents. Several mesh wires were fractured. The study demonstrated that mechanical strain combined with weak electric potential resulted in pronounced corrosion and fracture of stents, especially with overlapping stents. Single stents after pulsatile load released the lowest amount of ions. The combination of stents of the same material (Nitinol) had the highest release of metal ions.
动脉粥样硬化导致的动脉内狭窄通常采用血管内球囊扩张术联合金属支架进行治疗。再狭窄很常见，通常采用在现有支架内放置新支架或重叠放置支架来覆盖更大的血管面积来进行治疗。支架断裂、支架压缩、支架周围免疫活性细胞堆积的观察结果表明，支架释放的物质可能引发免疫反应。本研究建立了加速腐蚀模型以研究常用的外周血管支架的腐蚀行为。研究了 6 个单独的镍钛诺支架（n = 6）、相同材料（镍钛诺）的连接支架（支架内支架，n = 7）和不同合金（镍钛诺内有不锈钢支架）的连接支架（n = 7）。支架经受机械脉动径向应变（在 1 Hz 时应变最高可达 8%）和电化学应力（+112 mV 对 SCE）。比较了镍和钛离子的释放情况。获得了扫描电子图像。与单个支架（范围：0.4-216μg/L）相比，两个相似（范围：1382-8018μg/L，p = 0.0012）和不同（范围：170-2497μg/L，p = 0.0023）支架的组合时镍的释放更高。钛的浓度较低（范围：1.6-98.4μg/L），只有单个支架和两个相似支架之间存在差异（p = 0.0047）。在微动和点蚀腐蚀后，明显可见腐蚀产物的沉积物，主要在镍钛诺支架上。几个网丝断裂。研究表明，机械应变与弱电势相结合会导致支架明显腐蚀和断裂，尤其是重叠支架。脉动负载后的单个支架释放的离子量最少。相同材料（镍钛诺）支架的组合释放出最多的金属离子。
