Reducing the spring-back force of the aortic stent graft — decreasing the risk of stent graft-induced new entry

Objective

This study utilized patient-specific model to quantitatively analyze, from a mechanical perspective, the impact of reducing the spring-back force of the stent graft on the proximal and distal landing zones of the aorta after thoracic endovascular aortic repair (TEVAR).

Methods

A patient-specific aortic dissection (AD) model was established based on preoperative computed tomography angiogram (CTA) images. The stent graft structure, according to the stent graft actually used by the patient, was optimized to reduce spring-back force using the Isight (Dassault Systèmes, France) optimization design platform, in combination with the Kriging model and Non-dominated sorting genetic algorithm (NSGA-II). The final optimized stent graft was virtually implanted into the patient’s aorta and compared with the original stent graft to analyze, from a mechanical perspective, the impact of reducing the spring-back force of the stent graft on the proximal and distal landing zones after TEVAR.

Results

In the proximal landing zone, the peak value of maximum principal stress caused by the final optimized stent graft was 257.0 KPa, a 1.5 % reduction compared to the original stent graft. In the distal landing zone, the peak value of maximum principal stress was 148.7 KPa, a 19.9 % reduction compared to the original stent graft. The reduction in peak maximum principal stress in the distal landing zone was much greater than in the proximal landing zone. Before and after optimization, the location of the peak value of maximum principal stress in the distal landing zone remained at the boundary of the intima flap and was located on the greater curvature of the aorta.

Conclusion

Reducing the spring-back force of the stent graft can decrease the stress on the proximal and distal landing zones of the aorta, thereby reducing the risk of stent graft-induced new entry.