Atherosclerosis in large arteries has been linked to local haemodynamics. In some arteries, sites of low and oscillating wall shear stress (WSS) appear to coincide with sites of atherosclerotic plaque formation. This may be due to increased particle residence time near the wall and/or haemodynamic effects on the endothelium. Intima media thickness (IMT) of the arterial wall is an indicator of early atherosclerosis. We have studied relationships between WSS and IMT in the carotid arteries in normotensive and hypertensive subjects using realistic CFD models and in vivo measurements.

A novel 3D ultrasound technique was used to create realistic CFD models of the carotid bifurcations of 14 subjects (5 normotensives, 9 hypertensives, age 25-75). Flow simulations were carried out under subject-specific flow conditions obtained from pulsed Doppler ultrasound measurements in the proximal and distal internal and external carotid arteries. IMT was measured in the distal common carotid and the carotid bulb of each subject using B-mode ultrasound.

It was found that IMT could be related to mean WSS in the common carotid artery as the Pearson correlation coefficient was relatively high (r=−0.777; p=0.0179) while there seemed to be no evidence for such a relationship between IMT and the oscillatory shear index (OSI). Additionally, the hypertensives exhibited overall higher IMT and lower WSS than the normotensives. The outcome of this study seems to support the postulated relationship between WSS and IMT. However, more extensive research should be carried out with increased sample size and additional WSS parameters.