PROSPECTIVE, IN-VIVO STUDY OF THE RELATIONSHIP BETWEEN BLOOD-FLOW HEMODYNAMICS AND ATHEROSCLEROSIS IN A HYPERLIPIDEMIC SWINE MODEL

Purpose: This is the first prospective evaluation of the relationship between shear stress and atherosclerotic plaque formation in a pulsati le, in vivo model. Methods: A 50% aortic stenosis was created in six Y ucatan micropigs by placing a suture line across the left half of the aorta. A specially modified 20 MHz Doppler ultrasound probe mounted at a 45 degree angle on a micromanipulator was used to measure blood flo w velocity along the lateral aspects of the aorta. Shear stress at the se locations was calculated with linear regression. The pigs were then fed a specially formulated hyperlipidemic diet for 7 months, after wh ich their aortas were harvested. Plaque thickness was measured and cor related with mean, maximum, and minimum shear stress at each site and side on or away from the aortic plication and distance from the level of the aortic plication with general linear modeling. Results: Plaque thickness was negatively correlated with the mean shear stress during the cardiac cycle (correlation coefficient -0.3972 p = 0.0164) and wit h the maximum shear stress during the cardiac cycle (correlation coeff icient -0.4581 p = 0.0050). Plaque thickness was correlated with a mul tivariate model of mean shear stress, maximum shear stress, and their interactive effects with other parameters in the model with a correlat ion coefficient of 0.6733, (P = 0.0048). Conclusions: This is the firs t prospective, in vivo study with a pulsatile, hyperlipidemic model, w hich clearly demonstrates that low shear stress is associated with pla que formation. 1994:19:58-64.)