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Page 10 of 15 Qiu et al. Vessel Plus 2018;2:12 I http://dx.doi.org/10.20517/2574-1209.2018.13

Stress (MPa)

Strain
Figure 7. Constructed poly-L-lactic acid stress-strain curves for Absorb scaffold at different degradation time points [41]

Normalised ratio

Degradation time (days)

Figure 8. Radial strength and stiffness data obtained from simulation for Absorb scaffold compared to experimental data at different
degradation time points [41]

Material property of biodegradable polymer shows a difference during degradation, and therefore mechanical
behaviour of polymeric stents is also influenced by stent degradation. Several studies have been carried out
to predict the degradation behaviour of polymeric stents by developing constitutive models for degradable
material, but neglected stent-artery interaction during degradation. For the first time, Qiu et al. evaluated
[41]
the mechanical behaviour of a polymeric BRS using computational method, with a focus on stent-artery
interaction during the process of degradation and artery remodelling. In particular, stress-strain responses
were calibrated for polymeric stents over 2-year in vitro degradation period, according to experimentally
measured strength and stiffness [Figures 7 and 8]. Effect of degradation on stent behaviour was simulated
by considering the change of material’s property over time. In addition, vessel remodelling was simulated
by manually changing the geometry of diseased artery, following those published clinical data. Over 2-year
degradation times, stresses in the plaque and vessel layers showed a consistent decrease; while the stent
experienced an increase in stress at the beginning followed by a gradual decrease, corresponding to the
changing properties of the polymeric material [Figure 9]. In addition, vessel remodelling led to a reduction