Biaxial biomechanics of aged human carotid arteries

This study characterized the passive biaxial biomechanics of human common carotid arteries from 10 cadaver donors, with emphasis on physiologically relevant loading and the role of axial pre-stretch. Left and right common carotid artery segments were collected, marked for anatomical orientation, measured for axial pre-stretch, cut into planar square tissue samples, and mechanically tested under multiple biaxial stretch ratios. A thick-walled Holzapfel-Gasser-Ogden constitutive model was fitted to the planar biaxial data and then used to simulate tubular inflation-extension experiments that incorporated the measured in situ axial pre-stretch. The older adult donors had low axial pre-stretches of approximately 1.03 on the left and 1.01 on the right, while the 19-year-old donor showed higher values of 1.25 and 1.16. Simulations showed that pressure and axial stretch strongly influenced circumferential and axial stress, stiffness, strain energy density, and reduced axial force. Regional and bilateral differences were generally minimal, although right common carotid arteries had larger loaded inner diameters at low pressures, greater circumferential stiffness at 100 and 140 mmHg, and greater reduced axial force at 140 mmHg, while left arteries showed higher axial stiffness at 100 and 140 mmHg. The young donor’s arteries showed distinctively different mechanics, reinforcing the importance of aging in carotid artery biomechanics.