Abstract:

Objective    To explore the effects of increased, lowered and oscillatory wall shear stresses in the progress of atherosclerosis by placing the arterial cannula in the rabbit carotid artery. Method    According to the theory of hydromechanics, the rabbit model of atherosclerosis was established by the arterial cannula designed by us and a high fat diet. The data was detected at three designated time points, including the common carotid arterial intimamedia thickness(IMT), end diastolic diameter(Dr), systolic peak velocity(Vs), diastolic end velocity(Vd), mean velocity(Vm). Then, the shear stress was calculated.  At the end of 12 weeks, the rabbits were sacrificed, and arterial samples were obtained to observe the pathological changes in common carotid artery through hematoxylin and eosin stain. Results    The levels of the increased and lowered shear stresses caused by the cannula were significantly different from the basic line(both P<0.05),  the vascular ultrasound showed there was turbulent blood flow in the area of oscillatory shear stresses. Compared to the  oscillatory shear stresses, the area of the lowered shear stress contained bigger plaques, more lipids and smooth muscle cells, but less collagen. There was no obvious plague in the area of the increased shearstress. Conclusions    The cannula in the common carotid artery can induce different shear stresses, including increased, lowered and oscillatory, in different segments of a single artery. Increased shear stresses can inhibit atherosclerosis, while the lowered and oscillatory ones can boost its formation.

Key words: Wall shear stress; Cannula in common carotid artery; Atherosclerosis; Vascular ultrasound; Rabbit