Abstract
Understanding hemodynamics in blood circulation is crucial in order to unveil the mechanisms underlying the formation of stenosis and atherosclerosis. In fact, there are experimental evidences pointing out to the existence of some given vessel configurations that are more likely to develop the above mentioned pathologies. Along this manuscript, we performed an exhaustive investigation in a simplified model aiming to characterize by means of physical quantities those regions and configurations in vessel bifurcations that are more likely to develop such pathologies. The two-fold analysis is based, on the one hand, on numerical simulations (via CFD) and, on the other hand, on experiments realized in an ad-hoc designed polydimethylsiloxane (PDMS) channel with the appropriate parameters and appropriate fluid flows. The results obtained demonstrate that low velocity regions and low shear stress zones are located in the outer walls of bifurcations. In fact, we found that there is a critical range of bifurcation angles that is more likely to vascular disease than the others in correspondence with some experimental evidence. The effect of the inflow velocity on this critical range is also analyzed.
Highlights
Cardiovascular diseases, specially of ischemic etiology, are leading causes of death in humans[1]
We constructed an in-vitro idealization of a vessel bifurcation made with PDMS and made a sucrose flow circulate through it mimicking the actual blood circulation in a living being
An exhaustive investigation of both systems allowed us to determine the low flow velocity areas. Both sources of information yield to equivalent results. They demonstrate that low velocity zones and low shear stress areas are located in the outer walls of a bifurcation
Summary
Cardiovascular diseases, specially of ischemic etiology, are leading causes of death in humans[1]. Atherosclerosis is a chronic and systemic inflammatory disease of the arterial vessels characterized by the formation of intimal lesions (atherosclerotic plaques) in the vasculature. Despite the fact that the entire arterial tree is exposed to known systemic risks factors such as hypercholesterolemia, hypertension and diabetes, atherosclerotic plaques development occurs at geometrically predisposed areas, such as in the vicinity of branch points, the outer wall of bifurcations and the inner wall of curvatures, which are sites of low shear stress, turbulence and/or oscillating flow[2,3,4]. Our aim was to combine the numerical study with its experimental validation in order to define the predictable hemodynamic risk of planar arterial bifurcations. The flow remains during larger periods of time and (1) pathological particles have more time to deposit and bound to the vessel boundary, and (2) low shear stress at the endothelium of these zones make this “soil” more prone to disease
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