Experimental studies and numerical analysis of the inflation and interaction of vascular balloon catheter-stent systems.

Balloon angioplasty with stenting is a well-established interventional procedure to treat stenotic arteries. Despite recent advances such as drug eluting stents, clinical studies suggest that stent design is linked to vascular injury. Additionally, dilation of the medical devices may trigger pathological responses such as growth and migration of vascular smooth cells, and may be a potent stimulus for neointimal hyperplasia. The purpose of this study is to experimentally investigate the mechanical characteristics of the transient expansion of six commercially available balloon-expandable stent systems, and to develop a robust finite element model based on the obtained experimental results. To reproduce the inflation of stent systems as in clinical practice, a pneumatic-hydraulic experimental setup is built, able to record loads and deformations. Characteristic pressure-diameter diagrams for the balloon-expandable stents and the detached balloons are experimentally obtained. Additionally, typical measures such as the burst opening pressure, the maximum dog-boning and foreshortening, and the elastic recoil are determined. The adopted constitutive models account for elastoplastic deformation of the stent, and for the nonlinear and anisotropic behavior of the balloon. The employed contact algorithm, based on a C(2)-continuous surface parametrization, efficiently simulates the interaction of the balloon and stent. The computational model is able to successfully capture the experimentally observed deformation mechanisms. Overall, the numerical results are in satisfactory agreement with experimental data.