Geometric and mechanical changes along the length of the porcine aorta.

Abstract

The aorta, the primary artery responsible for carrying blood away from the heart, exhibits variations in its geometric and mechanical properties along its total length. Although these properties have individually been investigated in various animal and human studies, comprehensive assessments measuring all these parameters simultaneously along the entire aortic length have not been well reported. Consequently, current models predicting the aorta's in vivo mechanical state are based on separately obtained parameters and thus have inherent limitations. The present study systematically quantified variations in ex vivo diameter and wall thickness, in vivo axial stretch, and ex vivo biaxial mechanical properties along the descending thoracic and abdominal segments of five Yorkshire male porcine aortas. Consistent with earlier findings, diameter decreased from ∼13 mm to ∼3.6 mm and wall thickness decreased from ∼2.05 mm to ∼1.02 mm toward distal segments, whereas in vivo axial stretch increased from ∼1.15 to ∼1.5. Notably, the infrarenal abdominal aorta exhibited significantly higher axial stiffness compared to the mid-descending thoracic region (p < 0.05). Estimated in vivo axial stress was found to increase distally (slope = 0.1, p = 0.12), while estimated in vivo circumferential stress remained relatively constant throughout the porcine aorta's length (slope = 0.004, p = 0.96). These results suggest that during development, position-specific axial stretches, possibly driven by spinal elongation, induce adaptive remodeling of aortic geometry and material properties to maintain relatively uniform circumferential stresses. The resulting dataset provides a comprehensive, location-specific characterization of aortic geometry and mechanics to support future computational modeling studies.