Propagation of pressure pulse in kangaroo arterial system.

The pressure pulse contour in the ascending aorta of kangaroos is markedly different from that seen in other species, but the changes undergone by the pulse propagating along the aorta are quite similar. Alteration of wave contour and progressive amplification of the pulse in the distal aorta and peripheral arteries of other mammals have been attributed to elastic nonuniformity of the aorta and to peripheral wave reflection. In kangaroos the aorta approximates a uniform tube with essentially constant viscoelastic properties, whereas wave reflection from the lower body appears to be unusually intense and to emanate from a single functionally discrete reflecting site; this appears to be the result of arterial terminations in the muscular lower body. Intense wave reflection from the lower body is the dominant mechanism responsible for changes in the pressure pulse of kangaroos between the ascending aorta and peripheral arteries. Contour of the pulse in the ascending aorta is attributable to this and to close proximity of reflecting sites in the upper body.