Abstract
Drug-eluting stent (DES) is tiny wire mesh tubes coated with drug used to open narrowed and diseased coronary arteries. DES releases drug slowly to prevent scar tissue growth in the artery, which causes in-stent restenosis. However, clinical problems remain such as stent fractures and polymer coating detachment. During the balloon catheter expansion, DES has to undergo the plastic deformation. Moreover, after implantation, stent has to undergo the load given by the heart pulse. In this study, fatigue behavior of stent is investigated and morphologies of polymer coating in relation to stent expansion and cyclic strain were observed using scanning electron microscope (SEM) to assess the reliability of DES. Fatigue test of stent indicated that there were no significant differences in fatigue behavior between DES and bare-metal stent (BMS). From the SEM appearance, two kinds of irregularities caused by expansion process were observed in the coating of DES, that is, crack and delamination. Additionally, no significant increase of irregularities was found in the coating of DES after fatigue test.