A prediction of in vivo mechanical stresses in blood vessels using thermal expansion method and its application to hypertension and vascular stenosis

Mechanical stimuli play critical roles in cardiovascular diseases, in which in vivo stresses in blood vessels present a great challenge to predict. Based on the structural-thermal coupled finite element method, we propose a thermal expansion method to estimate stresses in multi-layer blood vessels under healthy and pathological conditions. The proposed method provides a relatively simple and convenient means to predict reliable in vivo mechanical stresses with accurate residual stress. The method is first verified with the opening-up process and the pressure-radius responses for single and multi-layer vessel models. It is then applied to study the stress variation in a human carotid artery at different hypertension stages and in a plaque of vascular stenosis. Our results show that specific or optimal residual stresses exist for different blood pressures, which helps form a homogeneous stress distribution across vessel walls. High elastic shear stress is identified on the shoulder of the plaque, which contributes to the tearing effect in plaque rupture. The present study indicates that the proposed numerical method is a capable and efficient in vivo stress evaluation of patient-specific blood vessels for clinical purposes.