Age-related changes in longitudinal prestress in human abdominal aorta

Studies on the influence of aging on the longitudinal mechanical response of elastic arteries are rare, though longitudinal behavior may have a significant effect on pressure pulse transmission. Our study was designed to elucidate how aging is reflected in changes of the longitudinal prestress, prestretch, and pretension force. The study involved ten human samples (six female and four male) of the abdominal aorta with longitudinal prestretch determined in autopsy. Cylindrical samples underwent a longitudinal elongation test in order to estimate the force necessary to attain the in situ length and to determine the corresponding axial prestress. The elastic modulus was estimated employing hyperelastic limiting chain extensibility model. It was found that pretension force, longitudinal prestress, and prestretch are negatively correlated with age. The decreased longitudinal force necessary to obtain the in situ length suggested that the decrease in the prestress occurs not only due to the age-related increase in the cross-section area. Since elastin is the main constituent responsible for bearing the prestretch, this suggests that the observed decrease in the longitudinal prestress and prestretch reflects aging-induced damage to the elastin. Finally, constitutive modeling showed that limiting chain extensibility is a concept that is suitable for describing the aging effect.