Particle Image Velocimetry Measurements of Blood Flow in a modeled Carotid Artery Bifurcation

Cardiovascular diseases such as atherosclerosis are one of the leading causes of death in the developed world and associated monetary pressure on public health systems is considerable. The initiation and development of these diseases still remain poorly understood, but it is becoming increasingly identifiable as a dysfunction of the endothelia layer, which lines the arterial walls. The prevailing haemodynamic environment plays an important role in the development of atherosclerosis in specific regions of the human vasculature. Locally disturbed haemodynamics lead to very low wall shear stress and reduces convection of important blood borne chemicals to the arterial wall. The presented work investigates blood flow in a modeled human carotid artery by means of planar digital Particle Image Velocimetry (PIV) to qualitatively measure and visualise local flow phenomena. A scaled model of a tuning fork shaped average human carotid artery (TF-AHCA) bifurcation was constructed in a transparent silicon rubber using Magnetic Resonance Imaging (MRI) data and a rapid prototyping technique combined with a two step casting process. A waterglycerin mixture was used to simulate steady in-vivo flow conditions and to match the refractive index of the flow phantom. PIV recordings were processed using an iterative crosscorrelation method with ensemble correlation averaging. Measurements were taken in the plane of bifurcation and results show a large region of low momentum fluid at the outer wall of the carotid. The curvature of the vessel walls introduces radial pressure gradients, which in turn lead to strong secondary flows. The flow inside the carotid bifurcation and downstream assumes a heliocoidal trajectory with a large region of low wall shear stress along the outer wall.