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Finite Element Shape Optimization for Biodegradable Magnesium Alloy Stents

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Abstract

Biodegradable magnesium alloy stents (MAS) are a promising solution for long-term adverse events caused by interactions between vessels and permanent stent platforms of drug eluting stents. However, the existing MAS showed severe lumen loss after a few months: too short degradation time may be the main reason for this drawback. In this study, a new design concept of MAS was proposed and a shape optimization method with finite element analysis was applied on two-dimensional (2D) stent models considering four different magnesium alloys: AZ80, AZ31, ZM21, and WE43. A morphing procedure was utilized to facilitate the optimization. Two experiments were carried out for a preliminary validation of the 2D models with good results. The optimized designs were compared to an existing MAS by means of three-dimensional finite element analysis. The results showed that the final optimized design with alloy WE43, compared to the existing MAS, has an increased strut width by approximately 48%, improved safety properties (decreased the maximum principal stress after recoil with tissue by 29%, and decreased the maximum principal strain during expansion by 14%) and improved scaffolding ability (increased by 24%). Accordingly, the degradation time can be expected to extend. The used methodology provides a convenient and practical way to develop novel MAS designs.

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Acknowledgments

The research is supported by a grant from the Fondazione Cassa di Risparmio di Trento e Rovereto, the financial support of the IIT through the project ‘Models and Methods for Degradable Materials’ and the financial support of the Politecnico di Milano through the project ‘Development of bioabsorbable magnesium alloy innovative stents’.

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Authors and Affiliations

  1. Laboratory of Biological Structure Mechanics, Department of Structural Engineering, Politecnico di Milano, Piazza Leonardo da Vinci, 32, 20133, Milan, Italy

    W. Wu, L. Petrini, D. Gastaldi, T. Villa & F. Migliavacca

  2. Department of Mechanical Engineering, Politecnico di Milano, Milan, Italy

    M. Vedani, E. Lesma & B. Previtali

Authors
  1. W. Wu
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  2. L. Petrini
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  3. D. Gastaldi
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  4. T. Villa
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  5. M. Vedani
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  6. E. Lesma
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  7. B. Previtali
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  8. F. Migliavacca
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Correspondence to L. Petrini.

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Associate Editor Jane Grande-Allen oversaw the review of this article.

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Wu, W., Petrini, L., Gastaldi, D. et al. Finite Element Shape Optimization for Biodegradable Magnesium Alloy Stents. Ann Biomed Eng 38, 2829–2840 (2010). https://doi.org/10.1007/s10439-010-0057-8

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  • DOI: https://doi.org/10.1007/s10439-010-0057-8

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