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Qiu et al. Vessel Plus 2018;2:12 I http://dx.doi.org/10.20517/2574-1209.2018.13 Page 13 of 15

Recoil (%)

Loading rate (MPa/s)

Figure 11. Recoiling effect of the Elixir stent for different loading rates [50]

shown in Figure 11. These results proved that polymeric stent behaved differently during expansion process
if the loading rate was different. With the increase of inflating rate, stent intended to expand further, with
reduced recoiling but higher level of stresses. These results suggest that loading rate should be taken as an
additional factor in the surgical practice of stent deployment.

CONCLUSIONS
Stents have been developed from BMSs, to DESs and then BRSs to prevent various complications and improve
their clinical efficacy. Materials are also extended from metal (e.g., stainless steel and cobalt-chromium
alloy) to biodegradable polymer (PLLA). For polymeric stents, experimental studies showed stent designs
and materials played an important role in the stent behaviour during expansion. Physical properties (e.g.,
mass weight and molecular weight) and mechanical properties (e.g., tensile strength and elastic modulus)
showed a difference during stent degradation. Computational approaches have also been used to study the
stent performance during expansion and degradation. However, the development of bioresorbable polymeric
stents is still ongoing, and studies are extremely limited due to the microscale geometry of stent and complex
environment of human artery. Therefore, further research is urgently required for a better understanding of
the mechanical performance of polymeric stents, including long term clinical outcomes.

DECLARATIONS
Authors’ contributions
Carried out the review and drafted the paper: Qiu T
Discussed about the technical contents and also contributed to the writing of the review paper: Zhao L

Availability of data and materials
Not applicable.

Financial support and sponsorship
None.

Conflicts of interest
All authors declared that there are no conflicts of interest.