Guardians Against Atherosclerosis? Deciphering the Role of a Vortex in Carotid Artery Health*

Carotid artery diseases, such as atherosclerosis, are significant contributors to mortality in the United States. While it is recognized that low wall-shear-stresses trigger plaque formation, specifically in the internal carotid artery sinus, there is limited understanding of why only certain patients are predisposed to form plaques.  Physiological pulsatile flow computational fluid dynamics simulations were performed on a ‘healthy’ and a ‘disease-prone’ carotid artery bifurcation model and a ‘hybrid’ model having a ‘healthy geometry with imposed disease-prone’ flow conditions’.  The models were constructed from patient-averaged anatomical clinical data for a healthy population and one which is predisposed to develop stenotic plaques.  

A hairpin vortical structure in the internal carotid artery sinus was observed to locally increase instantaneous wall shear stress to healthy levels, thus being physiologically beneficial.  However, in the ‘disease-prone’ geometry, this vortical structure has a significantly shorter lifespan. Results for the ‘hybrid’ model revealed that this shortened lifespan was due to the ‘disease-prone’ flow conditions, not the geometry (anatomical features). Playing a significant role in atherosclerotic plaque formation, this shortened vortex lifespan as well as its direct correlation to ‘disease-prone’ flow condition has the potential to facilitate clinical early diagnosis through medical imaging.