A 3D-LDA study of the relation between wall shear stress and intimal thickness in a human aortic bifurcation

A realistic model experiment on hemodynamics was performed to study correlations between wall shear stresses measured in a cast model of the aortic bifurcation and intimal thickness at each corresponding site of the native blood vessel from which the cast had been made. An elastic model of a 54 year old human aortic bifurcation was made of a polyurethane elastomer using a dipping method, and was perfused with Newtonian or non-Newtonian fluid under physiologic pulsatile flow condition. Local flow velocities were measured with an optical-fibered, 3-dimensional laser Doppler anemometer (3D-LDA) to determine wall shear stresses. Distribution of intimal thickness was determined using histological specimens of the native blood vessel. The results obtained are: 1) Non-Newtonian fluid rheology increased wall shear stresses; 2) Positive correlations were observed between intimal thickness and the maximum instantaneous wall shear stress, and 3) However, if we take only the data from the circumference at the level of the flow divider tip, there were negative correlations between them.