Hemodynamic characteristics of type I Endoleak and intra-prosthetic thrombus following endovascular aneurysm repair: A computational fluid dynamics study

BACKGROUND Endovascular aneurysm repair (EVAR) is preferred for abdominal aortic aneurysms (AAAs) due to minimal invasiveness, but complications like Type I endoleaks (T1EL) and intra-prosthetic thrombus (IPT) persist. While current risk prediction routinely involves anatomical assessment, the specific postoperative hemodynamic environments associated with these distinct complications remain under-investigated.

METHODS This study integrates patient-specific computed tomography (CT) angiography with a computational fluid dynamics (CFD)-based thrombus growth model to analyze postoperative geometries in 12 patients divided into three groups: T1EL, IPT, and no complications (Control). Key hemodynamic descriptors included flow patterns, wall shear stress (WSS), helicity, pressure gradients, and predicted thrombus distribution.

RESULTS T1EL patients showed complex flow patterns and distinct pressure gradients near the proximal or distal sealing zones. The IPT group exhibited significantly low time-averaged wall shear stress (TAWSS) and high relative residence time (RRT) within the graft limbs, fostering platelet aggregation. CFD simulations indicated different spatial distributions of potential thrombus formation between groups. Specifically, T1EL cases demonstrated stronger 3D helical flow features, while IPT cases had weaker rotational flow. Notably, graft geometry analysis revealed that cross-limb configurations induced specific flow disturbances distinct from standard configurations.

CONCLUSIONS By combining patient-specific biomechanics and thrombus modeling, this study offers new insights into the distinct flow phenotypes of post-EVAR complications. It highlights hemodynamic descriptors-helicity, TAWSS, oscillatory shear index (OSI), RRT, and endothelial cell activation potential (ECAP)-as potential quantitative metrics to complement anatomical assessment. Findings also suggest cross-limb graft configurations may modulate flow dynamics, potentially increasing thrombotic risk, providing preliminary clinical guidance requiring validation.