title: Electrical potentials between stent-grafts made from different metals induce negligible corrosion.
abstract: OBJECTIVE
  Evaluation of the risk of galvanic corrosion in various stent-grafts in current practice, when devices with unmatched alloy compositions are deployed together.
  
  
  METHODS
  Five nitinol (NT) and two steel (SS) stent-grafts produced by different companies were used in different combinations to create 21 samples (NT:NT, n = 10; NT:SS, n = 10; SS:SS, n = 1). Electric potential was measured between the metal couplings after immersion in 0.9% NaCl at a temperature of 37 °C. Subsequently, the same samples were incubated for 24 months in 0.9% NaCl at 37-39 °C under hermetic conditions and examined under a scanning electron microscope in order to search for any evidence of corrosion.
  
  
  RESULTS
  Electric potentials between different metals alloys were found (means: NT:SS, 181 μV; NT:NT, 101 μV; SS:SS, 160 μV). The mean electrical potential between stainless steel and nitinol samples was significantly higher than between NT:NT couplings (p < .001). During the final scanning electron microscope examination, only one spot of pitting corrosion (>10 μm) on a nitinol surface was found (associated with previous mechanical damage) in an NT:SS sample after 24 months of incubation in vitro and no sign of mechanical failure of the wires was found.
  
  
  CONCLUSIONS
  Direct contact between the stainless steel and the nitinol alloys does indeed create electrical potential but with a minimal risk of galvanic corrosion. No evidence was found for significant galvanic corrosion when two endovascular implants (stent-grafts) made from different metal composition were used in the same procedure.
authors.affiliation: Department of Vascular Surgery and Angiology, Pomeranian Medical University, Szczecin, Poland. Electronic address: biker2000@wp.pl.
authors.forename: A
authors.initials: A
authors.lastname: Kazimierczak
authors.forename: W
authors.initials: W
authors.lastname: Podraza
authors.forename: S
authors.initials: S
authors.lastname: Lenart
authors.forename: I
authors.initials: I
authors.lastname: Wiernicki
authors.forename: P
authors.initials: P
authors.lastname: Gutowski
mesh_terms: D000497:Alloys / Q000737:chemistry*; D001807:Blood Vessel Prosthesis; D003343:Corrosion; D004553:Electric Conductivity; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D011474:Prosthesis Design; D011475:Prosthesis Failure; D012307:Risk Factors; D012965:Sodium Chloride / Q000737:chemistry; D013193:Stainless Steel / Q000737:chemistry*; D015607:Stents; D013499:Surface Properties; D013696:Temperature; D013997:Time Factors
chemical_list: D000497:Alloys; D013193:Stainless Steel; C013616:nitinol; D012965:Sodium Chloride
keywords: Electrical potentials; Galvanic corrosion; Pitting corrosion; Stent-graft