Annals of Biomedical Engineering

, Volume 44, Issue 2, pp 419–431 | Cite as

Webbing and Delamination of Drug Eluting Stent Coatings

  • C. Hopkins
  • C. A. Sweeney
  • C. O’Connor
  • P. E. McHugh
  • J. P. McGarry
Medical Stents: State of the Art and Future Directions


The advancement of the drug-eluting stent technology raises the significant challenge of safe mechanical design of polymer coated stent systems. Experimental images of stent coatings undergoing significant damage during deployment have been reported; such coating damage and delamination can lead to complications such as restenosis and increased thrombogenicity. In the current study a cohesive zone modeling framework is developed to predict coating delamination and buckling due to hinge deformation during stent deployment. Models are then extended to analyze, for the first time, stent-coating damage due to webbing defects. Webbing defects occur when a bond forms between coating layers on adjacent struts, resulting in extensive delamination of the coating from the strut surfaces. The analyzes presented in this paper uncover the mechanical factors that govern webbing induced coating damage. Finally, an experimental fracture test of a commercially available stent coating material is performed and results demonstrate that the high cohesive strength of the coating material will prevent web fracture, resulting in significant coating delamination during stent deployment.


Drug eluting stent Coating Delamination Buckling Webbing Cohesive zone modeling 


  1. 1.
    Basalus, M. W. Z., M. J. K. Ankone, G. K. van Houwelingen, F. H. A. F. de Man, and C. von Birgelen. Coating irregularities of durable polymer-based drug-eluting stents as assessed by scanning electron microscopy. EuroIntervention. J. Eur. Collab. Work. Group Interv. Cardiol. Eur. Soc. Cardiol. 5:157–165, 2009.Google Scholar
  2. 2.
    Basalus, M. W. Z., K. Tandjung, T. van Westen, H. Sen, P. K. N. van der Jagt, D. W. Grijpma, A. A. van Apeldoorn, and C. von Birgelen. Scanning electron microscopic assessment of coating irregularities and their precursors in unexpanded durable polymer-based drug-eluting stents. Catheter. Cardiovasc. Interv. Off. J. Soc. Card. Angiogr. Interv. 79:644–653, 2012.CrossRefGoogle Scholar
  3. 3.
    Basalus, M. W., and C. von Birgelen. Benchside testing of drug-eluting stent surface and geometry. Interv. Cardiol. 2:159–175, 2010.CrossRefGoogle Scholar
  4. 4.
    Bedair, T. M., Y. Cho, B. J. Park, Y. K. Joung, and D. K. Han. Coating defects in polymer-coated drug-eluting stents. Biomater. Biomed. Eng. 1:121–141, 2014.Google Scholar
  5. 5.
    Denardo, S. J., P. L. Carpinone, D. M. Vock, C. D. Batich, and C. J. Pepine. Changes to polymer surface of drug-eluting stents during balloon expansion. JAMA 307:2148–2150, 2012.CrossRefPubMedGoogle Scholar
  6. 6.
    Feerick, E. M., X. (Cheryl) Liu, and P. McGarry. Anisotropic mode-dependent damage of cortical bone using the extended finite element method (XFEM). J. Mech. Behav. Biomed. Mater. 20:77–89, 2013.CrossRefPubMedGoogle Scholar
  7. 7.
    Feerick, E. M., and J. P. McGarry. Cortical bone failure mechanisms during screw pullout. J. Biomech. 45:1666–1672, 2012.CrossRefPubMedGoogle Scholar
  8. 8.
    Garg, S., and P. W. Serruys. Coronary Stents: Current Status. J. Am. Coll. Cardiol. 56:S1–S42, 2010.CrossRefPubMedGoogle Scholar
  9. 9.
    Garg, S., and P. W. Serruys. Coronary stents: looking forward. J. Am. Coll. Cardiol. 56:S43–S78, 2010.CrossRefPubMedGoogle Scholar
  10. 10.
    Hopkins, C. G., P. E. McHugh, and J. P. McGarry. Computational investigation of the delamination of polymer coatings during stent deployment. Ann. Biomed. Eng. 38:2263–2273, 2010.CrossRefPubMedGoogle Scholar
  11. 11.
    Hopkins, C., P. E. McHugh, N. P. O’Dowd, Y. Rochev, and J. P. McGarry. A combined computational and experimental methodology to determine the adhesion properties of stent polymer coatings. Comput. Mater. Sci. 80:104–112, 2013.CrossRefGoogle Scholar
  12. 12.
    Lee, S., C. W. Lee, and C.-S. Kim. FEA study on the stress distributions in the polymer coatings of cardiovascular drug-eluting stent medical devices. Ann. Biomed. Eng. 42:1952–1965, 2014.CrossRefPubMedGoogle Scholar
  13. 13.
    Levy, Y., D. Mandler, J. Weinberger, and A. J. Domb. Evaluation of drug-eluting stents’ coating durability–clinical and regulatory implications. J. Biomed. Mater. Res. B Appl. Biomater. 91:441–451, 2009.CrossRefPubMedGoogle Scholar
  14. 14.
    Máirtín, É. Ó., G. Parry, G. E. Beltz, and J. P. McGarry. Potential-based and non-potential-based cohesive zone formulations under mixed-mode separation and over-closure—part II: finite element applications. J. Mech. Phys. Solids 63:363–385, 2014.CrossRefGoogle Scholar
  15. 15.
    Mani, G., M. D. Feldman, D. Patel, and C. M. Agrawal. Coronary stents: a materials perspective. Biomaterials 28:1689–1710, 2007.CrossRefPubMedGoogle Scholar
  16. 16.
    McGarry, J. P., É. Ó. Máirtín, G. Parry, and G. E. Beltz. Potential-based and non-potential-based cohesive zone formulations under mixed-mode separation and over-closure. Part I: theoretical analysis. J. Mech. Phys. Solids 63:336–362, 2014.CrossRefGoogle Scholar
  17. 17.
    McGarry, J. P., B. P. O’Donnell, P. E. McHugh, E. O’Cearbhaill, and R. M. McMeeking. Computational examination of the effect of material inhomogeneity on the necking of stent struts under tensile loading. J. Appl. Mech. 74:978–989, 2007.CrossRefGoogle Scholar
  18. 18.
    O’Brien, B., and W. Carroll. The evolution of cardiovascular stent materials and surfaces in response to clinical drivers: a review. Acta Biomater. 5:945–958, 2009.CrossRefPubMedGoogle Scholar
  19. 19.
    Otsuka, Y., N. A. F. Chronos, R. P. Apkarian, and K. A. Robinson. Scanning electron microscopic analysis of defects in polymer coatings of three commercially available stents: comparison of BiodivYsio, Taxus and Cypher stents. J. Invasive Cardiol. 19:71–76, 2007.PubMedGoogle Scholar
  20. 20.
    Parry, G., and P. McGarry. An analytical solution for the stress state at stent–coating interfaces. J. Mech. Behav. Biomed. Mater. 10:183–196, 2012.CrossRefPubMedGoogle Scholar
  21. 21.
    Petrini, L., W. Wu, D. Gastaldi, L. Altomare, S. Farè, F. Migliavacca, A. G. Demir, B. Previtali, and M. Vedani. Development of biodegradable magnesium alloy stents with coating. Fract. Struct. Integr. 29:364–375, 2014.Google Scholar
  22. 22.
    Sweeney, C. A., P. E. McHugh, J. P. McGarry, and S. B. Leen. Micromechanical methodology for fatigue in cardiovascular stents. Int. J. Fatigue 44:202–216, 2012.CrossRefGoogle Scholar
  23. 23.
    Virmani, R., G. Guagliumi, A. Farb, G. Musumeci, N. Grieco, T. Motta, L. Mihalcsik, M. Tespili, O. Valsecchi, and F. D. Kolodgie. Localized hypersensitivity and late coronary thrombosis secondary to a sirolimus-eluting stent should we be cautious? Circulation 109:701–705, 2004.CrossRefPubMedGoogle Scholar
  24. 24.
    Waterhouse, A., Y. Yin, S. G. Wise, D. V. Bax, D. R. McKenzie, M. M. M. Bilek, A. S. Weiss, and M. K. C. Ng. The immobilization of recombinant human tropoelastin on metals using a plasma-activated coating to improve the biocompatibility of coronary stents. Biomaterials 31:8332–8340, 2010.CrossRefPubMedGoogle Scholar
  25. 25.
    Wiemer, M., T. Butz, W. Schmidt, K.-P. Schmitz, D. Horstkotte, and C. Langer. Scanning electron microscopic analysis of different drug eluting stents after failed implantation: from nearly undamaged to major damaged polymers. Catheter. Cardiovasc. Interv. Off. J. Soc. Card. Angiogr. Interv. 75:905–911, 2010.Google Scholar
  26. 26.
    Wu, W., M. Mercuri, C. Pedroni, F. Migliavacca, and L. Petrini. A computational study to investigate debonding in coated bioresorbable stents. J. Mech. Med. Biol. 15:1540015, 2015.CrossRefGoogle Scholar
  27. 27.
    Wu, W., L. Petrini, L. Altomare, S. Farè, R. Tremamunno, Y. Zhentao, and F. Migliavacca. Modeling and experimental studies of peeling of polymer coating for biodegradable magnesium alloy stents. Rare Met. Mater. Eng. 43:2877–2882, 2014.CrossRefGoogle Scholar

Copyright information

© Biomedical Engineering Society 2015

Authors and Affiliations

  • C. Hopkins
    • 1
  • C. A. Sweeney
    • 1
  • C. O’Connor
    • 1
  • P. E. McHugh
    • 1
  • J. P. McGarry
    • 1
  1. 1.Biomedical Engineering, College of Engineering and InformaticsNational University of Ireland GalwayGalwayIreland

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