Vascular Tissue Response to Experimentally Altered Local Blood Flow Conditions

Abstract

Local factors related to shear stress may influence atherogenesis through several mechanisms. It is probably for this reason that lesion development does not show a consistent relation to shear stress when different experimental models are compared. Thus, there is currently emphasis on the correlation that has been observed between low shear and lesion formation in several experimental models, for example, the human carotid bifurcation studied by Ku and co-workers (1985).As these investigators point out, however, it is often difficult to divorce low shears from shears that fluctuate rapidly in magnitude and especially in direction. Furthermore, atherosclerosis occurs in high shear regions in some models, although it now appears that this is not commonplace and tends to be species specific. Indeed, frequent sparing of high shear regions has raised speculations of adaptive responses to shear. Finally, it frequently appears that reproducible lesions may be distributed at sites not well correlated with shear stress. Thus, the distribution of lesions within the aorta of animals or humans is not readily related to available maps of aortic shear in mammals.