Assessment of structure integrity, corrosion behavior and microstructure change of AZ31B stent in porcine coronary arteries

Abstract Magnesium alloy coronary stent becomes a hot research topic due to its biodegradable character for avoiding late thrombosis and late restenosis. However, fracture of Mg alloy stent was a common issue after implantation. In this study, 18 drug-eluting biodegradable AZ31B stents were implanted into porcine coronary arteries to assess its structural integrity, corrosion behavior and microstructure change in vivo . The coronary artery tissue responses to AZ31B stent implantation were detected by quantitative coronary angiography and optical coherence tomography at the set time periods. In addition, further analyses were focused on the stent structure integrity, corrosion behaviors and the microstructure change of Mg alloy stents after implantation. A large number of fractures on stent struts were observed by high-resolution transmission X-ray tomography clearly. Moreover, degradation products, twins and grain refinement that appeared in Mg alloy stent matrix after implantation were also observed during the study. Inferred from this study, it is shown that the loss of AZ31B stent structural integrity may be the result of stress concentration, degradation and microstructure change.