Modeling the coupling between stent degradation and vascular remodeling considering the effects of mechanical stimuli and geometric interaction

Abstract

Background and objectives

The degradation of stents and vascular remodeling are processes involving mechanical and geometric interactions. However, in previous studies, these two processes were treated as independent. This study aims to develop a finite element coupling model based on the constitutive and stress-growth relationships to investigate the impact of mechanical stimuli and geometric interactions on the coupled process.

Methods

A stent degradation model that incorporates multiple corrosion factors and a vascular remodeling model that considers artery stress stimuli were first established. Then, these two models were coupled on spatio-temporal scales, and the mechanical and geometric interactions between them were carefully configured by setting material properties and corrosion properties for the individual element as well as marking the element status. Based on this coupling model, we simulated stent degradation and vascular remodeling under different mechanical and geometric interaction conditions.

Results

Compared to constant initial stress stimuli following stent deployment, dynamic stress stimuli during the coupling process prolonged stent fracture time by 4 % due to reduced stress corrosion and altered the neointima volume trend from a continuous linear increase to a gradual convergence by mitigating artery damage. Furthermore, the dynamic changes in geometric interaction during coupling extended stent fracture time by 24 % through the neointima's coverage of the stent.

Conclusions

These findings highlight the significant influence of dynamic mechanical stimuli and geometric interactions on the coupling outcomes. Therefore, it is crucial to incorporate these factors into the coupling model. Ultimately, this model may provide a biomechanical foundation for understanding the supporting performance, degradation rate, and in-stent restenosis of biodegradable vascular stents in clinical settings.