Experimental Broad-Based Curved Sidewall Aneurysms in Rabbits Mimicking Human Carotid Siphon Aneurysms: Proof of Feasibility and Comparability Using Computational Fluid Dynamics

Abstract

Broad-based sidewall aneurysms of the carotid artery are primarily treated endovascularly. However, recurrence or rupture after treatment still pose a significant risk. Hence, reliable animal models mimicking this aneurysm type are essential for to evaluate the performance of new advanced endovascular devices. Experimental aneurysms were created in 12 New Zealand white rabbits (2.5-3.5kg). The human carotid siphon was mimicked with an end-to-end anastomosis of both common carotid arteries. A venous pouch was sutured on the convexity to mimic a broad-based side wall aneurysm. Patency and configuration was investigated 4 weeks postoperatively by 3 T-MRA. To compare flow conditions of broad-based sidewall aneurysms in rabbits and humans exemplary computational fluid dynamics (CFD) simulations were performed using species specific blood viscosity values. We were able to achieve 0% peri- or postoperative mortality. Patency was confirmed by 3T-MRA in 11 out of 12 aneurysms (91.7%). Aneurysm lengths ranged from 6.4 - 9.8mm and aneurysm necks from 7.3-9.8mm. CFD showed simple flow profiles with one vortex in rabbit as well as in human aneurysms. Wall shear stress (WSS) rates were comparable using species-specific blood viscosity values (rabbit mean 1.65 Pa vs. human mean 1.7 Pa). The broad-based curved sidewall aneurysm model mimicking the carotid siphon showed high aneurysm patency rates with low morbidity. High comparability with human flow patterns and human intranaeurysmal biomechanical forces was shown using simulations.