AbstractObjectives: to study the relationship between wall shear stresses measured in vivo and early atherosclerotic lesions in the abdominal aorta. Materials: eight young volunteers for in vivo wall shear-stress measurements. Abdominal aortas from 10 young adults without signs or history of atherosclerotic disease were obtained by autopsy for histomorphometric measurements. Methods: wall shear stresses were measured in the abdominal aorta above and below the renal arteries using a magnetic resonance technique with high resolution for imaging and blood velocity mapping. At identical abdominal aortic locations, intimal thickness was measured blindly using histomorphometric techniques and correlated to wall shear-stress variables using linear-regression analysis. Results: intimal thickness showed a linear decrease with mean wall shear stress (r=−0.90, p<0.01) and with maximum wall shear stress (r=−0.86, p<0.01). Conclusions: intimal thickness in the normal abdominal aorta is associated with mean, maximum and oscillating wall shear stresses. These in vivo data corroborate previous in vitro studies suggesting that low and oscillating wall shear stresses are localising factors for intimal thickening and hence the early development of atherosclerosis
