Load-dispersing design with twined-spring geometry of a distensible intracranial stent for cerebral aneurysms

Endovascular stents are increasingly being used to treat cerebral aneurysms. Mechanically, a cerebrovascular stent must have a low radial stiffness to prevent vessel dissection and rupture. To minimize these complications, we need to consider a stent design that has a low radial force and disperses the load within the stented artery. Therefore, highly distensible, load-dispersion stent designs are desirable for intracranial stenting. This study focused on closed-cell stent geometries and calculated the differences in stress within the artery because of the structure by using finite-element modeling. The results showed that the design with hexagonal cell geometry stretched in the circumferential direction had lower radial and circumferential stresses than did the other models. Comparing the maximum radial stress of our models, stress reduction of 35% was obtained with this design. Moreover, its radial stress was 47 kPa, which was similar to the critical stress of 42 kPa assumed in this study. This stent model was characterized by narrow strut spacing and a large surface area, which was dominated by the twined-spring geometry. It had low radial and circumferential stresses and a dispersed stress distribution compared with the other models. Therefore, this design is a desirable load-dispersing design for cerebrovascular treatment.