Nitinol is generally considered biocompatible and corrosion resistant for many in-body applications. It has been successfully used in permanent cardiovascular, orthopedic and urologic implants. In spite of this general acceptance literature reports can be found that describe nitinol degradation after relatively short term, 1 month, in-vivo exposure. Device processing is frequently targeted as the cause for negative results but it is important to confirm the sample cleaning methods do not alter the explanted device.

The present work examined the impact of several tissue removal and cleaning methods on pristine Vanguard AAA stent-grafts. Results showed significant nitinol wire degradation after cleaning in commercial bleach but no noticeable degradation with dilute sodium hydroxide or Tergazyme(R) enzymatic cleaner. Surface analysis performed on similar stent-grafts implanted for up to 60 months showed no signs of nitinol wire frame degradation.