The role of shear stress in the localization and progression of atherosclerosis in the carotid district: evaluation with echo-color-doppler

Aim. Low values of shear stress have an important role hi determining the preferential localization of atherosclerotic lesions in some vascular areas. The purpose of our study is to measure shear stress in the carotid area of healthy subjects, using the echo_color Doppler method, and further evaluating the potential role in the future development of atheromasic lesions and suggesting a new calculation scheme. Methods. Initially we evaluated echographically (ATL Ultramark 9) the possible atheromasic undertaking of carotid vessels in 4 767 subjects (45-85 years old) hospitalized at our Institute or under care in our medical clinic, not chosen for pathology or symptoms presented. Then, we calculated shear stress (0.1584 × acceleration of blood flow, in dyne/cm2) in the carotids of 54 healthy volunteers (35±4 years), in order to hypothesize under which forces the pathologic carotids of subjects composing the first group were subjected to in the past. The results were compared to the Student t test. Results. We found a greater number of atherosclerotic lesions and shear stress values significantly lower in the internal carotids with respect to the external and common ones. We did not find a preferential distribution of the pathology regarding the 2 sides. Conclusion. Exploiting the study model which was reasonably rapid in the progression of the atherogenic process and alternative to a study of the longitudinal type, we propose a new, simple, calculation method of in vivo shear stress: early evaluation in a healthy subject, of this hemodynamic force predisposed to atherosclerosis, could, potentially predict which vascular area is more at risk, and therefore, is worth serial evaluation in time.