IDENTIFICATION OF ATHEROPRONE MORPHOLOGICAL FEATURES IN WALL SHEAR STRESS WAVEFORMS IN CAROTID BIFURCATIONS: A CFD-BASED INTEGRATEDAPPROACH

摘要

Vascular endothelial cells functions are modulated by shear stress at vessel wall. The presence of 'abnormal' blood flow patterns can give rise to local variations from physiological wall shear stress (WSS) time histories. These variations might be risk factors that increase a vessel's atherosusceptibiliry.Several studies [e.g., 1] suggest that the shape of the WSS waveforms in carotid bifurcations is an important factor both in the onset and progression of atherosclerosis, but they do not delineate which morphological features are most atheroprone. In this preliminary study we propose a CFD-based integrated approach aimed at identifying, if any, atheroprone morphological features in WSS waveforms in a 3D-OD coupled model of carotid bifurcation. In detail, we firstly solved the unsteady flow field within the coupled model. Then, we reduced the dimension of the dataset of the computed WSS(t) waveforms (i.e., the modulus of the WSS vector) by means of Self Organizing Maps (SOMs). Finally, we applied on the reduced dataset the Principal Component Analysis (PCA). This allowed us to discriminate WSS waveforms from regions of abnormal flow and waveforms from regions where the flow is less disturbed (as measured by the haemodynamic descriptor Relative Residence Time, RRT [ 1,2]) only on the basis of their morphological features.