Penetration Mechanics of Endovascular Stent Graft Barbs in Aortic Tissue

Endovascular stent grafts with barbs — tiny needle-like pins that provide active fixation — are increasingly used for treating aortic aneurysms and dissections. Characterization of barb penetration mechanics may help improve stent-graft designs. Barb angle varies among manufacturers (10–50°). But little is known regarding aortic wall penetration characteristics in relationship to barb angle. There is a body of work on needle insertion properties such as insertion forces into soft tissues. However, there have not been specific studies involving the aorta and the relationship between entry angle and entry force. Kratzberg et al. [1,2] demonstrated that barb angle was closely related to penetration angle and that lower angles between the barb and the body of the aortic stent-graft resulted in better penetration probability and fixation strength in the aortic wall. In order to assess why lower barb angles (i.e., barb axis closer to the graft axis) resulted in better penetration, this study investigates the relationship between barb penetration angle and aortic tissue entry force and compared it to a homogeneous control membrane made of silicone.