Endograft-specific hemodynamics after endovascular aneurysm repair: a CFD analysis

Intraluminal prosthetic graft thrombus (IPT) has been described in case of endovascular aortic pathology repair. This study aimed to assess hemodynamic indicators associated with various anatomical morphologies following endovascular aortic repair (EVAR), aiming to offer further references for the choice of clinical therapy. Six model models (normal, iliac compression, aortic compression, aortoiliac compression, iliac distortion, and long-leg stent) were established based on common anatomical morphologies following EVAR. Hemodynamic indicators, such as flow velocity, time-average wall shear stress (TAWSS), oscillatory shear stress index (OSI), and relative residence time (RRT), were captured using computational fluid dynamics (CFD), and the differences between the six models were examined. The peak blood flow velocity at the compressed side iliac artery and the uncompressed side iliac artery corresponding to the aortoiliac artery compression model and the aortic compression model decreased by 30.63% to 48.62%, compared with that in the normal model. Compared with that in the normal model, the peak blood flow velocity at the aorta and the distorted side iliac artery in the iliac distortion model decreased by 7.89% and 41.13%, respectively. The length of the iliac artery stent has little effect on the blood flow velocity. The TAWSS at Iliac grafts showed varying degrees of decline in the other three compression models, particularly in the aortic compression model compared to the normal model. The TAWSS increases at the corner of the artery showing distortion but exhibited a significant decrease toward the distal end of the corner. The areas with higher OSI, and longer RRT were concentrated in the aortoiliac compression model and the iliac distortion model. We found that endograft compression and distortion may be risk factors for IPT. Moreover, the influence of longer stents on the hemodynamics inside stent-grafts is negligible. However, future real-world studies should be conducted to test and verify this speculation.