Sex different abdominal artery anatomy may induce different displacement force on stent-graft after endovascular aneurysm repair

Women with abdominal aortic aneurysm (AAA) have a higher incidence of complications after Endovascular aneurysm repair (EVAR), most of which are related to the migration of stent-graft. The different force acting on the stent-graft after EVAR caused by different abdominal artery anatomy of male and female AAA patients may be the reason for the sex-different complications. This article aims to explore the possible biomechanical mechanisms of sex differences by making a comparison of displacement force acting on the stent graft of male and female AAA patients. To explore the effect of different vascular anatomy on stent-graft migration, the uniformed models were constructed according to the specific vascular anatomy parameters of AAA patients of different sex, which have been measured before. The computational fluid dynamics method was used to quantitate the pulsatile force acting on the stent-graft after EVAR in a cardiac cycle. Then the displacement force was calculated with the pressure and the wall shear stress, and the total and area-weighted average of displacement force acting on the stent-graft were compared respectively. In one cardiac cycle, the wall pressure for the male model is greater than that of the female model (2.7-4.4 vs. 2.2-3.4 N), and the wall shear force for the female model is slightly greater (0-0.0065 vs. 0-0.0055 N). The displacement force is mainly provided by the wall pressure, which is also greater in the male model. However, the area-averaged displacement force is greater for the female model than that for the male model (180-290 vs. 160-250 Pa). Because of the different vascular anatomies, the impact caused by the pulsating aortic blood flow on the AAA stent-graft of women after EVAR was greater than that of men. Women's vascular anatomy leads to greater area-averaged displacement force after stent-graft implantation, resulting in a greater risk of stent-graft migration, which might be one of the reasons why women had a higher incidence of complications after EVAR.