Finite Element Analysis and Evaluation of Bare Metal Stent in the Treatment of Aortic dissection from the Perspective of Stent Size and False Lumen area

Abstract

Endovascular aortic repair is considered a mainstream treatment for aortic dissection. Although stent-grafts have demonstrated positive effects, they still have several limitations. Our team proposes implanting a self-expandable bare metal stent at the lesion site to close tears through its chronic outward forces. This novel treatment strategy aims to improve intervention outcomes and reduce long-term risks. As part of the ongoing preclinical evaluation, we used finite element analysis to examine bare metal stent interventions for aortic dissection. Different false lumen areas were achieved by varying the intimal flap locations in the aorta (10, 30, and 50% of the aortic diameter), and peeling of an intimal flap was simulated by finite element analysis. The sizes of the bare metal stent were set at 30, 32, and 34 mm. In the 30% dissection model, 32- and 34-mm bare metal stents successfully closed two tears, reducing the area ratio between the lumens from 12% to less than 6%, while also ensuring good contact with the aortic wall. These two stent sizes changed the cross-sectional shape of the aorta, producing higher stress on the blood vessel wall. Similar shape changes were observed in the 50% dissection model with a 32-mm bare metal stent; however, the true lumen area was still enlarged. In contrast, a 32-mm bare metal stent was sufficient to reduce the false lumen in the 10% dissection model, whereas a larger stent was required for the 50% dissection model. In conclusion, simulations showed tear closure and reduction of the false lumen area by the chronic outward force of the stent. Use of a bare metal stent with an oversizing ratio of 1.2-1.4 is recommended. Although the interventions may change the cross-sectional shape of the aorta, expansion of the true lumen can still be guaranteed. Unlike stent-grafts, therapeutic outcomes with bare metal stents depend on the degree of intimal flap deformation and the degree of struts-wall contact; therefore, the expansion capability of the stent itself is essential for this treatment.