Hemodynamic Effect of Unequal Anterior Cerebral Artery Flow Rates on the Anterior Communicating Artery Bifurcation: A Computational Fluid Dynamics Study

Computational fluid dynamics techniques were used to investigate the hemodynamic effectof unequal anterior cerebral artery flow rates on the anterior cerebral and anterior communicatingartery (ACA-ACOM) bifurcation. Hemodynamics have long been implicated as a majorfactor in cerebrovascular disease. Using an idealized 2D symmetric model of the ACA-ACOMgeometry, the flow field and wall shear stress (WSS) at the bifurcation regions are assessedfor pulsatile inflows with left to right flow ratios of 1:1, 2:1, 3:1, and 4:1. Unequal flow ratesthrough the ACA parent arteries result in bifurcation of the higher flow parent stream and ashifting of the impingement points along the A2-ACOM adjoining wall toward the contralateral ACA. Cross-flow through the ACOM is generally unstable and results in increased WSSat the impingement region from the higher flow parent artery and a double amplitude peakin the WSS at the contralateral bifurcation region from local recirculation effects. These resultssuggest that asymmetry in ACA flow rates result in increased hemodynamic stresses at the ACA-ACOM bifurcation regions and suggest a possible factor for vessel weakening andaneurysm formation