Aortic mechanics in the living dog

Abstract

The relationship between longitudinal strain, circumferential strain, lateral intravascular pressure, blood velocity, and longitudinal motion was examined in the aortas of 25 living thoracotomized dogs. Electrical calipers with adequate recording characteristics were used for instantaneous measurement of diameter and length. The results indicate: a) with inspiration, the thoracic aorta increased in length and the abdominal aorta shortened. b) During cardiac systole the length in the thoracic aorta increased with a rise in pressure, mean value for longitudinal extensibility x 10 3 was 15% (α 4.8 S.D., α 1.1 S.E.M.) per centimeter H 2 O pulse pressure. The mean value for the ratio of circumferential extensibility to longitudinal extensibility was 10. c) The abdominal aorta shortened with cardiac systole. This shortening is thought to be produced by elongating strain of the thoracic aorta. d) The absolute magnitude of aortic wall velocities, both radial and longitudinal, was very small as compared to the blood velocity at the same site. Submitted on August 18, 1960