This study aims to investigate whether displacement force on stents can accurately represents the displacement of the stent after endovascular aneurysm repair (EVAR) by comparing the measured stent displacement with the displacement forces calculated by computational fluid dynamics (CFD). And the effect of cross-limb and parallel-limb EVAR on stent displacements is further studied. Based on our objective, in this study, ten cross-limb EVAR patients and ten parallel-limb EVAR patients in West China Hospital of Sichuan University were enrolled. Patient-specific models were first reconstructed based on the computed tomography angiography images, then the stent displacements were measured, and the displacement forces acting on the stents were calculated by CFD. Finally, the \begin{document}$ \mathrm{cos}\;\alpha $\end{document} value of the angle between the displacement force and the displacement vector was used to analyze the matching degree between the displacement and the displacement force. The results showed that the displacement forces on cross-limb stents and parallel-limb stents were (2.67 ± 2.14) N and (1.36 ± 0.48) N, respectively. Displacements of stent gravity center, stent displacements relative to vessel, and vessel displacements of cross-limb and parallel-limb stents were (4.43 ± 2.81) mm and (6.39 ± 2.62) mm, (0.88 ± 0.67) mm and (1.11 ± 0.71) mm, (3.55 ± 2.88) mm and (5.28 ± 2.52) mm, respectively. The mean \begin{document}$ \mathrm{cos}\;\alpha $\end{document} for cross-limb and parallel-limb stents were 0.02 ± 0.66 and − 0.10 ± 0.73, respectively. This study indicates that the displacement force on the stent can’t accurately represent the displacement of the stent after EVAR. In addition, the cross-limb EVAR is probably safer and more stable than the parallel-limb EVAR.
Objective To investigate the technical feasibility and effectiveness of intraoperative sac embolizaion with coils and fibrin glue for preventing type Ⅱ endoleak after endovascular aneurysm repair (EVAR). Methods A patient with abdominal aortic aneurysm (AAA), which had high risk of type Ⅱ endoleaks, was treated with combined packing of coils and fibrin glue in order to prevent type Ⅱ endoleak after EVAR. Percutaneous catheter preset and balloon occlusion were used to ensure accurate packing. Results At the end of the operation, the angiography showed that the blood flow of the stent and distal artery was unobstructed, there was no type Ⅰ and Ⅲ endoleaks, and delayed angiogram showed no collateral circulation of aneurysm. The procedure was successful. The operative duration was 120 min and the blood loss was only 20 mL. No complications such as colonic ischemia and ectopic embolism occurred, and the patient was discharged on 3 days after operation. At 6 months after follow-up, the computerized topographic angiography showed that the aneurysm cavity was completely thrombotic, without type II endoleak, and the diameter and volume of aneurysm were reduced. Conclusions The technique of intraoperative sac embolizaion with coils and fibrin glue during EVAR is safe and effective to prevent postoperative endoleaks, which is simple and feasibility. Intraoperative indwelling catheter and balloon blocking are the key points of successful implementation of this technique.