Deformation characteristics of a bioabsorbable intravascular stent

Rationale and objectives: Biodegradable polymeric stents offer an alternative to metallic stents, which have a significant compliance mismatch with blood vessels and have the potential for long-term complications. In the current study, the deformation characteristics of polymeric stents have been investigated. Methods: Stents were subjected to radial compressive pressure by inserting them in a wrap-around collar, one end of which was loaded in tension using dead-weights. The resulting decrease in stent diameter was measured under an optical microscope. Deformation curves for the stents were plotted, and an effective stiffness, E', was determined for each. Results: The deformation curves exhibited two different regions: an initial linear region, followed by a steep nonlinear region. The transition from the linear region occurred at a fractional decrease in stent diameter of approximately 0.5. Conclusion: E’ decreases with increasing stent diameter and filament draw-ratio. The relationship between E' and the initial stent diameter is not linear. The deformation curves can be used for choosing the appropriate stents for specific applications.