Abstrakt
The research in the field of cardiovascular biomechanics is focused primarily on the heart and blood vessels, but the surrounding tissues, on the other hand, are often overlooked in the literature. This study shows that the human perivascular adipose tissue can significantly affect mechanical response of the human abdominal aorta.
Analytical model of incompressible bilayer thick-walled closed cylindrical tube has been created and subsequently used to simulate the inflation-extension response of the aorta surrounded with adipose tissue. The inner layer, abdominal aorta, was assumed to exhibit residual stresses.
The material of this layer was considered as anisotropic and was described by hyperelastic nonlinear constitutive model. The outer layer, fat tissue, was considered to be a hyperelastic isotropic material which does not exhibit residual stress.
The outer radius of the aorta and inner radius of the external fatty tube were considered to be equal during the pressurization and axial stretch. The inflation-extension response of bilayer tube was compared with one-layer representing only the abdominal aorta.
The simulations showed that the abdominal aorta is more compliant in the circumferential and axial direction in comparison with the fat tissue. The Cauchy stress across the wall thickness of bilayer model and the one-layer tube was determined and compared.
The plot of the Cauchy stress versus deformed radius proved that the radial stress satisfies the boundary condition σrr(riA) = -P, ρrr(r0p) = 0 and σrr(r0A) = σrr(riP). An abrupt change in the axial stress by approx. 80 kPa occurs on the contact between the aorta and perivascular tissue.
The results of this study suggest that the surrounding tissue should not be neglected in the modeling of blood vessels.