The Effect Of Carotid Artery Bifurcation Anatomy And Hemodynamics On Wall Shear Stress Based On Ultrasound Vector Flow Imaging(V Flow) Technique

Objective To investigate the effect of carotid artery bifurcation anatomy and hemodynamics on wall shear stress by using ultrasound vector flow imaging（V Flow）technique.Methods A total of 70 normal patients with carotid artery ultrasound examination were selected as the study subjects.Place the region of interest of V Flow at the bifurcation of the carotid artery.The ratio(D_CB/D_CCA)of the inner diameter of carotid bulb(D_CB)where the area is the most obvious expansion at the end-systolic to the inner diameter of terminal segment of common carotid artery(D_CCA)was measured.The angle between the carotid bulb and the common carotid artery was measured.The ratio(Q_CB/Q_CCA)of the blood flow of the carotid bulb(Q_CB)to the terminal segment of common carotid artery(Q_CCA)was measured.Recording the visualized area of blood flow disorder in the carotid bulb(A_CB),and measuring the average shear stress of the inner wall&outer wall of the carotid bulb,The above parameters were analyzed by statistical method.Results （1）The WSS_I-CBvalue of the inner wall of the carotid bulb was（0.88±0.30）Pa,and the WSS_E-CB value of the outer wall was（0.32±0.15）Pa,The WSS_E-CB value of the outer wall was significantly smaller than the WSS_I-CB of the inner wall,and the difference was statistically significant（P<0.01）.（2）The angle between the carotid bulb and the common carotid artery was（24.5±12.1）°,and the correlation coefficient with WSS_E-CB was r=-0.171,and that there was no correlation between them,the difference was not statistically significant（P>0.05）.The ratio of the most obvious enlargement of carotid bulb to the inner diameter of common carotid artery(D_CB/D_CCA)was（0.66±0.09）,which was negatively correlated with WSS_E-CB value,and the correlation coefficient was r=-0.312,and the difference was statistically significant（P<0.05）.（3）The ratio of the volume of carotid bulb to the volume of terminal carotid artery(Q_CB/Q_CCA)was（0.69±0.15）,which was positively correlated with WSS_E-CBvalue,and the correlation coefficient was r=0.428,and the difference was statistically significant（P<0.01）.The area of blood flow disorder in the carotid bulb(A_CB)was（0.27±0.17）cm²,which was negatively correlated with WSS_E-CBvalue,and the correlation coefficient was r=-0.545,and the difference was statistically significant（P<0.01）.Conclusions The blood flow of internal carotid artery,the area of the bifurcation where the blood flow is diffuse amorphous,and the degree of bulbar enlargement are the main factors affecting the lateral wall WSS,but it is not closely related to the angle of the internal carotid artery.