Age-related wall shear stress changes assessed by vascular vector flow mapping in the carotid arteries of healthy adults: a cross-sectional study.

Background: Wall shear stress (WSS) is related to the pathogenesis of atherosclerosis. WSS is affected by a variety of hemodynamic factors, and there is still a lack of accurate and objective methods for measuring it. This study sought to evaluate hemodynamic changes in WSS_{maximum (max)}, WSS_mean, WSS_{minimum (min)} in the common carotid artery of healthy adults of different ages using vascular vector flow mapping (VFM).

Methods: A retrospective analysis was conducted on 70 healthy volunteers aged 20-89 years who were recruited from our Ultrasound Department between February 2021 and June 2021. An ultrasound system with a 3-15 MHz probe was used to determine regions of interest (ROIs) of the common carotid artery. VFM-based WSS measurements were obtained by selecting ROIs with optimal image quality from three full cardiac cycles. The participants were divided into the following seven age groups: the 20s group, the 30s group, the 40s group, the 50s group, the 60s group, the 70s group, and the 80s group. The WSS parameters were compared among the age groups. An analysis of variance or a Kruskal-Wallis test was used to evaluate the difference among the groups, and a Pearson analysis and linear regression were used for the correlation and trend analysis.

Results: The WSS parameters were quantified using vascular VFM software. The WSS_max, WSS_mean, WSS_min differed among the age groups and gradually decreased with age, the elderly were significantly lower than the young. The Pearson correlation coefficient of the WSS_max and age was -0.556 (P<0.001), that of the WSS_mean and age was -0.461 (P<0.001), and that of the WSS_min and age was -0.308 (P<0.001). The WSS parameters with age are negatively correlated the carotid intima-media thickness differed between the groups.

Conclusions: The carotid WSS_max, WSS_mean, WSS_min can be quantitatively and visually analyzed using the vascular VFM technique. In healthy adults of different ages, the carotid WSS_max, WSS_mean, WSS_min decreased with age. Our findings about the normal values of carotid WSS maybe have clinical reference value for future studies.