Validation of Compliance Zone at Cerebral Arterial Bifurcation Using Phantom and Computational Fluid Dynamics Simulation

Objective: A zone compliant to pulsatile flow (compliance zone) showing evagination and flattening at the apex of the cerebral arterial bifurcation was documented in our previous report using electrocardiogram-gated computed tomographic and magnetic resonance angiography. We aimed to validate the existence of compliance zones and examine their relationship to local thin-elastic walls. Methods: We examined different bifurcating vascular models: a phantom with a thin elastic region at the apex and computational fluid dynamics models with either an elastic or rigid region at the apex of a bifurcation. Results: In the phantom, the elastic region at the apex of the bifurcation showed evagination and flattening in time with the pulsatile circulating fluids. The size of the evaginations increased when the outlet side was tilted down below the level of the flow-generating pump. Pulsatile evagination could be simulated in the computational fluid dynamics model with an elastic region at the bifurcation apex, and the pressure gradient was highest in the evaginating apex in peak systolic phase. Conclusions: We were able to demonstrate a compliance zone, which responds to pressure gradients, experimentally, in the form of a thin elastic region at an arterial bifurcation.