Corrosion Resistance,Surface Evaluation,and Geometric Design Comparison of Five Self-Expanding Nitinol Stents Used in Clinical Practice

Abstract

Purpose

To investigate the corrosion resistance properties of 5 commercially available nitinol stents used to treat peripheral artery disease and compare their surface quality, elemental composition, and geometrical design.

Methods

Samples of 5 different designs of nitinol peripheral stents [LifeStent (n=4), Philon (n=6), Epic (n=6), S.M.A.R.T. Control (n=7), and Complete SE (n=7)] were examined using stereomicroscopy, environmental scanning electron microscopy, and x-ray photoelectron spectroscopy. Corrosion resistance testing was performed in accordance with ASTM International Standard F2129-08.

Results

Thirteen (43%) of 30 stents corroded during this experiment. Stent fracture was observed in 12 (92%) of these corroded stents. Mean breakdown potentials ranged from 517 to 835 mV (vs. Ag/AgCl) for the Philon, Complete SE, S.M.A.R.T. Control, Epic, and LifeStent models from lowest to highest. A statistically significant difference in breakdown potential was observed between the LifeStent vs. Philon stents (835 vs. 517 mV, p=0.01) and Epic vs. Philon stents (833 vs. 517 mV, p=0.03). Stents with lower breakdown potential and relative breakdown potentials were associated with a higher fracture frequency (Spearman correlation coefficient −0.44, p=0.015 and −0.869, p<0.01, respectively).

Conclusion

In this in vitro study, corrosion led independently to stent fracture. There is a significant association between lower mean breakdown/relative breakdown potentials and stent fracture.

Keywords

peripheral artery disease in vitro study nitinol stents corrosion surface properties stent fracture

Get full access to this article

View all access options for this article.

References

Scheinert

Sax

Prevalence and clinical impact of stent fractures after femoropopliteal stenting. J Am Coll Cardiol. 2005;45:312–315

Adlakha

Sheikh

Stent fracture in the coronary and peripheral arteries. J Interv Cardiol. 2010;23:411–419

Heintz

Riepe

Birken

Corroded nitinol wires in explanted aortic endografts: an important mechanism of failure?

J Endovasc Ther. 2001;8:248–253

Jacobs

Won

Gravereaux

Mechanical failure of prosthetic human implants: a 10-year experience with aortic stent graft devices. J Vasc Surg. 2003;37:16–26

Riepe

Heintz

Kaiser

What can we learn from explanted endovascular devices?

Eur J Vasc Endovasc Surg. 2002;24:117–122

Guidoin

Marois

Douville

Firstgeneration aortic endografts: analysis of explanted Stentor devices from the EUROSTAR registry. J Endovasc Ther. 2000;7:105–122

Halwani

Anderson

Brott

Clinical device-related article: surface characterization of explanted endovascular stents: evidence of in vivo corrosion. J Biomed Mater Res B Appl Biomater. 2010;95:225–238

Russel

Ni-45Ti. In: ASM International ed. Materials and Coatings for Medical Devices: Cardiovascular, 1st ed. Materials Park, OH, USA: ASM International; 2009:94–112

ASTM Standard F2129-2008. Standard Test Method for Conducting Cyclic Potentiodynamic Polarization Measurements to Determine the Corrosion Susceptibility of Small Implant Devices. West Conshohocken, PA, USA: ASTM International; 2008:1–9

10.

Stoeckel

Bonsignore

Duda

A survey of stent designs. Minim Invasive Ther Allied Technol. 2002;11:137–147

11.

Weldon

McHugh

Carroll

The influence of passivation and electropolishing on the performance of medical grade stainless steels in static and fatigue loading. J Mater Sci Mater Med. 2005;16:107–117

12.

Stoeckel

Pelton

Duerig

Self-expanding nitinol stents: material and design considerations. Eur Radiol. 2004;14:292–301

13.

Shabalovskaya

Rondelli

Rettenmayr

Nitinol surfaces for implantation. J Mater Eng Perform. 2009;18:470–474

14.

Shabalovskaya

SA.

Physicochemical and biological aspects of nitinol as a biomaterial. Int Mater Rev. 2001;46:233–250

15.

Trépanier

Tabrizian

Yahia

Effect of modification of oxide layer on NiTi stent corrosion resistance. J Biomed Mater Res. 1998;43:433–440

16.

Steegmueller

Fleckenstein

Schuessler

Is electropolishing equal electropolishing? A comparison study of nitinol stents. In: Venugopalan

eds. Medical Device Materials III Proceedings of the Materials & Processes for Medical Devices Conference [held Nov 14–16, 2005, in Boston, MA, USA]. Materials Park, OH, USA: ASM International; 2006:163–168

17.

Rosenbloom

Corbett

An assessment of ASTM F2129 electrochemical testing of small medical implants-lessons learned. In: Corrosion 2007 Conference & Expo [held March 11–15, 2007, in Nashville, TN, USA]. Houston, TX, USA: NACE International; 2007. Available at: www.corrosionlab.com/papers/NACE2007.pdf . Last accessed January 8, 2014

18.

U.S. Food and Drug Administration. Guidance for industry and FDA staff-non-clinical engineering tests and recommended labeling for intravascular stents and associated delivery systems. April 18, 2010. Available at: www.fda.gov/MedicalDevices/DeviceRegulationandGuidance/GuidanceDocuments/ucm071863.htm . Last accessed January 8, 2014