Abstract 522: Computational Fluid Dynamics Analyses Of Geometric Incompatibility And Seal Zone Stability In Endovascular Aneurysm Repair

Abstract

Introduction: Long-term durability of endovascular aneurysm repair (EVAR) is often compromised due to inadequate sealing of the endograft to the aorta. We hypothesize that geometric mismatch between the aorta and endograft can lead to the development of bird-beak regions, type Ia endoleaks, and endograft migration. Our novel computational model shows how geometric incompatibility at the seal zone contributes to endoleak formation and propagation. Methods: Using finite-element modeling, we simulated endograft crimping and deployment in pressurized aortic models with different degrees of curvature (0°, 30°, 60°) and oversizing (0%, 20%, 25%). We then performed computational fluid dynamics (CFD) modeling with a detailed pressure analysis of various regions along the length of each model. Results: Across our models, pressure gradients developed between the bulk flow and endoleak regions. For all degrees of curvature, the average total pressure in the endoleak region was higher than that of the bulk flow in the 20% and 25% oversized models. While oversizing decreased the aorta-endograft geometric mismatch in the 60° model and mitigated the volume of endoleak, too much oversizing in the 0° models worsened endoleak. Conclusions: We present one of the first computational models to study the sensitivity of seal zone mechanics to the degree of aorta-endograft mismatch. Our finding of pressure gradients that exist between the endoleak and bulk flow may represent regions of high mechanical instability that may further propagate the endoleak. Our results highlight the importance of shape and oversizing considerations when selecting the appropriate endovascular therapy for EVAR patients. Figure 1: CFD simulations of aorta-endograft models with different degrees of curvature and oversizing show endoleak formation as a function of geometric incompatibility.