Longitudinal strain of canine and porcine aortas.

The in situ longitudinal strain of canine and porcine aortas was investigated. Marks of black water-resistant ink were placed on the aortas and the axial lengths between the marks were measured in situ and in vitro. When the aortas were cut, the retraction was measured and described by the stretch ratio, which is defined as the length of a segment in situ divided by the length at no-load state. Results show that the stretch ratios of both porcine and canine aortas increase monotonically from 1.2 in the descending region to about 1.5 in abdominal region. Species differences are seen in the middle region. In both animals, the stretch ratio is correlated to the cross-sectional area of the vessel wall.