Guidelines for tracheal stent costumization and implantation

Abstract

One of the treatments of tracheal stenosis is by stent implantation to reopen the constricted trachea lumen. However, post-stenting complications such as stent migration has been reported. This migration is due to undersized implanted stent. On the other hand, oversized implanted stent may pose excessive stress onto the wall of the trachea. Therefore, there is a need to customize the stent size according to the patients’ requirements. Thus, this thesis proposes a correlation of a customized stent that addresses the two problems mentioned. The analysis of a healthy trachea is performed and the effect of the different locations of the stenosis is investigated. Then, the effects of implantations of selected stents are numerically studied. The stents are also subjected to several mechanical testing for failure analysis. The results show that the developed stent is able to withstand various mechanical loads and deformation. The currently developed stent performed better than that of the commercial stent by at least 60 percent in bending test, 10 percent in radial compression test and 15 percent in torsional test. The stent is then tested at various tracheal stenosis locations. For a stenosed trachea, the location of the stenosis at the bottom part will pose the highest risk to breathing problems. Post-stenting results show that the developed stent is able to revert the flow inside the trachea to the original flow conditions. The flow rate distributions to the right bronchus were reduced by more than 30 percent as compared to flow rate distributions in healthy trachea. Finally, a correlation is proposed to enable stent customization that best fits patients’ requirements. This customized stent is predicted to be able to address the stent migration problem and excessive stress exerted to the trachea wall.