Investigation of PET-braided vascular stents potential compared with commercial metallic stents

Abstract

Braided polymeric biomedical stents were developed as an alternative to replace commercial metallic ones presenting several failures caused especially by the used metals. Among those materials, the polyethylene terephthalate PET has been used to develop stents since it is suitable for several biomedical uses, such as vascular prosthesis. But in order to obtain the ideal PET-braided stent, its manufacturing parameters should be carefully chosen. For that, the current study aims at developing polymeric braided vascular stents made of PET monofilaments. According to a two-level fractional factorial design, stents are braided by varying most of their manufacturing and heat-setting parameters (monofilament diameter, stent diameter, braiding angle, heat-setting temperature and heat-setting time). Then, the structural (cover factor, porosity, unchanged bending diameter) and mechanical tests (radial compression, longitudinal compression, longitudinal elongation) are performed. Developed stents performances are compared to those of the Gore's Nitinol stents. Then, effects of manufacturing parameters on stents properties were investigated. After selecting the significant parameters for each performance, optimal values were determined. According to the experimental results, manufactured stents showed good performances comparing to Nitinol stents. According to the factorial analysis, considered factors have different effects from a response to another. The most common significant factors are monofilament diameter, stent diameter and braiding angle, whereas the least important factors are heat-setting temperature and heat-setting time. Also, models are adequate (p-value < 0,05 and R2 > 80%) at the 95% confidence level. Furthermore, the obtained optimum stent's manufacturing settings can lead to PET-braided stents as performant as Gore's Nitinol ones.