A biphasic, anisotropic model of the aortic wall

A biphasic, anisotropic elastic model of the aortic wall is developed and c ompared to literature values of experimental measurements of vessel wall ra dii, thickness, and hydraulic conductivity as a function of intraluminal pr essure. The model gives good predictions using a constant wall modulus for pressures less than 60 mmHg, but re,quires a strain-dependent modulus for p ressures greater than this. In both bovine and rabbit aorta, the tangential modulus is found to be approximately 20 times greater than the radial modu lus. These moduli lead to predictions that, when perfused in a cylindrical geometry, the aortic volume and its specific hydraulic conductivity are rel atively independent of perfusion pressure, in agreement with experimental m easurements. M, the parameter that relates specific hydraulic conductivity to tissue dilation, is found to be a positive quantity correcting a previou s error in the literature.