Pressure-diameter relations of excised aorta

¹ Department of Physiology, Medical College of Georgia, Augusta, Georgia

A length of abdominal aorta was excised, and volume pulses were made at different pressure values by volume injections. The expected diameter changes were calculated from a static stretch curve made from a ring cut from the vessel. External diameter changes were recorded by a transformer coil. The two sets of data could be compared only after calculating the expected changes in wall thickness. Agreement was good enough to conclude that both techniques could measure wall extensibility. When the vessel was elongated to the in situ length, the external diameter showed an appreciable decrease. If wall volume was constant, this could be accounted for by a wall thinning. With such elongation, circumferential extensibility was clearly decreased. The vessel wall was almost isotropic at pressure values above 50 mm Hg, but at lower pressures it showed evidence of an architectural nonhomogeneity in its stretch behavior.