Issue 16

R. Laczkó et alii, Frattura ed Integrità Strutturale, 16 (2011) 28-33; DOI: 10.3221/IGF-ESIS.16.03 31 4.5/30 mm stent In the picture below (Fig.6) it is seen clearly how the flanges stick up on the strut of the stent. The struts were deformed sorely. Figure 6 : The head of the electrode during extraction (left) and the deformed stent after the procedure (right). 3.5/10 mm stent This is a drug eluting stent in a reservoir-base stent design. The stent became completely deformed and turned across in the tube which would involve grave consequences for human vessels during explantation. The reservoirs and slim parts of the struts may concentrate strain which may weaken the mechanical characteristics. Fig. 7 shows electron microscopic photographs of the damaged stent. Figure 7 : Deformed shape and damages to a reservoir stent. 3.5/10 mm stent The stent slipped out and was sheared as the electrode was removed. In the case of in vivo implantation, endothelisation occurs over time so a stent slipping out may cause internal injury. Figs. 8 and 9 demonstrate the stent became deformed during electrode extraction. Figure 8 : the beginning of electrode extraction Figure 9 : “S”-shaped stent after extraction