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Corroded nitinol wires in explanted aortic endografts : an important mechanism of failure?
Publikationstyp
Journal Article
Date Issued
2001-08-06
Sprache
English
Author(s)
Heintz, Carsten
Riepe, Gunnar
Kaiser, Edelgard
Chakfé, Nabil
Imig, Herbert
Journal
Volume
8
Issue
3
Start Page
248
End Page
253
Citation
Journal of Endovascular Therapy 8 (3): 48-253 (2001)
Publisher DOI
Scopus ID
Purpose: To analyze surface alterations and fractures observed in the nitinol stent wires of explanted endovascular grafts used for treatment of abdominal aortic aneurysm. Methods: Twenty-one explanted Stentor devices and 1 Cragg stent were received from investigators in Germany and France. After macroscopy and photography, the explants were cleaned and the polyester coating removed. The frame was examined completely by stereomicroscopy, and irregularities were assayed by scanning electron microscopy and energy dispersive x-ray analysis (EDAX). The observed alterations were classified according to stereomicroscopic and electron microscopic morphology. Results: The mean implantation interval for the endografts was 29.1 ± 13.2 months (range 5-46). All examined explants, even those retrieved after only a few months in situ, showed pitlike surface damage 10-25 μm in diameter. Larger, irregularly shaped surface alterations were observed in ∼70% of the explants. Older explants (age >32 months) presented vast regions of decay, with bending of the wire and stress cracks in some areas. EDAX examination revealed decreased nickel concentration in the corroded regions. Conclusions: Corrosion of the nitinol wire in endovascular grafts is confirmed. Presumably, the observed pitting and irregularly shaped corrosion defects are the precursors of material failure. They weaken the thin wire, which leads to stress cracks and eventually fracture of the stent wire under circulatory pulsation. Cell-induced electrochemical corrosion and active cellular destruction of surfaces are well-known mechanisms that must be investigated for their possible roles in the corrosion of stent metals.
Subjects
Endograft
Material fatigue
Pitting corrosion
Stentor
Wire fracture
DDC Class
610: Medicine, Health