The influence of post angioplasty stent implant profile on arterial wall stress

One of the main causes for post angioplasty arterial restenosis is the excessive stress induced in the arterial wall during and after the medical intervention. The closed stent is introduced in the artery wrapped around the deflated balloon catheter and is expanded in the final position by inflating the balloon. Unfortunately, this process also stretches the arterial wall. Additionally, for the stent to be successful, its diameter must be slightly larger than the diameter of the inflated artery. The stent is usually a dense mesh of interconnected beams. Therefore, it is often considered that it applies a constant pressure to the artery / stent interface. However, in reality each beam individually presses against the innermost layer of the artery (intima). The current study proposes a model, which predicts the arterial wall subsurface stress field due to individual stent beams. It was found that the local shape of the contact (beam cross section) plays an important role close to the stent / intima contact. Sharper edged cross sections (e.g. square) promote higher stresses. It was observed that during restenosis a new inner layer (neointima) is formed, significantly reducing the stent efficiency. This could be related to local stress concentrations due to the choice of stent beam profile.