AJP - Heart and Circulatory Physiology, Vol 247, Issue 1 95-H99, Copyright © 1984 by American Physiological Society
Directional disparity of pulse reflection in the dog
J. K. Li, J. Melbin and A. Noordergraaf
Local reflection coefficients were experimentally determined in the dog for
the first time at the aortoiliac junction using characteristic impedances
derived from phase velocity, fluid density, and the vessels'
cross-sectional areas. Reflection coefficients were determined for both the
normal trifurcation and with the segment of aorta between external and
internal iliacs occluded. For the normal case the coefficients were as
follows: antegrade, 0.7; retrograde, -0.74. For the occlusion case the
coefficients were as follows: antegrade, 0.33; retrograde, -0.67. These
results provide experimental support for the concept that the vascular
system, at least in this region, favors antegrade and suppresses retrograde
pulse transmission. In addition, global reflection coefficients were
determined in the femoral artery using a three-point pressure technique.
Coefficient magnitudes varied from low (1.6 Hz) to high (9.6 Hz)
frequencies, i.e., control, 0.42-0.22; vasoconstriction, 0.65-0.33;
vasodilation, less than 0.1 for all frequencies. Discrepancies between
results appearing in the literature are evaluated and shown to be
associated with the method utilized as well as with system nonlinearities
enhanced by tying branches.
