Jiaxuan Chen

The emergence of biodegradable stents addresses the limitations of the long-term presence of permanent bare metal stents in the human body. Following implantation, these stents can significantly reduce the occurrence of chronic complications such as inflammation and thrombosis, thus becoming a mainstream approach in the treatment of interventional cardiovascular diseases. Currently, the materials used for biodegradable stents are typically polymers. However, the inherent properties of the materials dictate that polymer stents exhibit lower mechanical performance and biocompatibility. Magnesium alloy materials, on the basis of their biodegradability, exhibit superior mechanical performance when compared to polymers, possessing the potential to address this issue. However, the presence of stress concentration in the stent structure necessitates further designs and mechanical performance analyses of magnesium alloy stents. In this work, a biodegradable stent based on WE43 alloy is designed. The stent incorporates the micro-protrusion structure to enhance the mechanical performance. Furthermore, to evaluate the clinical applicability of the stent, the mechanical performance of the biodegradable magnesium alloy stent is conducted through finite element analysis (FEA). The results show that the maximum equivalent stress in all four aspects is below the ultimate tensile strength of 370 MPa for the WE43 magnesium alloy, demonstrating excellent mechanical performance. Additionally, after crimping and expansion, the radial support strength and radial support force reached 780 mN/mm and 1.56 N, respectively. Compared to the advanced reported stent structures, the radial support strength and radial support force are enhanced by 13% and 47%, respectively. Additionally, flexibility analysis indicated that the flexibility of the stent design in this study is improved by a factor of 9.76, ensuring the stent’s capability to navigate through complex vasculature during implantation.

The shedding of thrombosis can pose diagnostic difficulties for clinicians as it results in risks of damage. Determining the appropriate treatment, drug thrombolysis, implanted vascular stents, clinical research, or surgical cutting is often challenging. To better understand the interfacial mechanical mechanism of thrombus shedding, a fluid-solid coupling finite element model was created based on viscoelasticity-based blood vessels, line elastic thrombosis, and Euler fluid blood to establish a connective interface between blood vessels and thrombosis. Under hypertension conditions, the interface mechanics model calculated the finite element interface performance of thrombosis with different degrees of calcification, thicknesses, and coverage angles, using the mechanical parameters to assess damage for the interface of different structural thromboses. The study analyzed and clarified the evolution mechanism of damage and exfoliation of the thrombotic interface in blood vessels under various conditions. The results revealed that the mechanics of damage and the shedding mechanism of the thrombosis were significantly affected by the different coverage angles. Based on these analyses, this study determined that the finite element method based on the Coupled Eulerian–Lagrangian method, including the interface model of the cohesive zone volume element layer, could well simulate the mechanics of damage and the shedding mechanism of the thrombotic interface under the impact of hypertension. This study is the first to explore the finite element interface damage model of thrombosis and the vessel wall using interfacial mechanics.