Correlation between intimal thickness and fluid shear in human arteries.

A realistic pulsatile flow was passed through a cast of the aortic bifurcation of a 63-year-old male with mild atherosclerosis, and a laser Doppler anemometer was used to measure fluid velocities in the cast at 15 selected sites near the lateral and medial walls. Intimal, medial and adventitial thickness were measured, and sudanophilia was scored, at corresponding sites in the vessel from which the cast had been made. A negative correlation was found between intimal thickness (IT) and wall shear rate (i.e., the velocity gradient at the blood-artery interface). The strongest negative correlation (P less than 0.005) was between IT and "pulse shear rate" (PSR), defined by analogy with pulse pressure. Sudanophilia also correlated negatively with PSR (P less than 0.01). These results suggest that large excursions of interfacial shear, at levels too low to cause damage, may inhibit intimal thickening.