Wall shear stress and early atherosclerotic lesions in the abdominal aorta in young adults

Objectives:To study the correlation between wall shear stress and early atherosclerotic lesions in the abdominal aorta.Design:Blinded histomorphometric studies. Comparison with in vitro data.Materials:Abdominal aortic haemodynamics were simulated in a realistic pulsatile flow model. Abdominal aortas from 10 young adults with no signs of atherosclerotic disease were obtained during autopsy.Methods:Quantitative wall shear stresses were measured at rest and exercise in one suprarenal and two infrarenal positions using laser Doppler anemometry. Intimal thickening indices were measured blindedly at the corresponding locations using histomorphometric methods, and compared to wall shear stress variables using linear regression analysis.Results:Intimal thickness index increased significantly with age. Intimal thickness index was significantly lower in the suprarenal than the infrarenal aorta, and higher at the distal posterior vessel wall compared to the anterior wall. Intimal thickness index correlated significantly with mean, minimum and oscillating wall shear stresses measured at rest.Conclusion:Intimal thickness in the undiseased abdominal aorta correlated significantly with mean, minimum and oscillating wall shear stresses at rest measured in a pulsatile flow model. No correlations were found with maximum shear stress parameters. Exercise changed the local wall shear stresses away from the characteristics associated with intimal thickness index