Material properties of different layers of aorta

The arterial wall has been considered as a single homogeneous layer vessel in a wide range of biomechanical modeling of aorta from traumatic injury to stent grafts, ignoring the fact that arteries are composed of distinct anatomical layers with different mechanical characteristics. In this study, changes in the mechanical properties of porcine thoracic aorta wall in the radial direction were characterized using a custom-made nanoindentation technique and a quasi-linear viscoelastic model. Two layers of equal thickness were mechanically distinguishable based on the radial variations in the instantaneous Young's modulus E and reduced relaxation function G(t). The results showed that the outer half layer was stiffer and showed less relaxation than the inner half one. These layers may correspond to media and adventitia in the specimens.