Pulse wave reflections from arterial discontinuities.

The true or characteristic velocity of pulse waves along different arterial segments in both animals and man often permits the determination of the elastic state of the vessels in health and disease. In this study, the extent to which the measured, or apparent pulse wave velocity (PWV) suffers from reflection effects is investigated. An in vitro test-rig is used to demonstrate that PWV, measured in an elastic tube model, will oscillate about the value characteristic of the vessel wall, as distance progresses close to a discontinuity-generating reflection. These variations are shown to be markedly reduced if the segment length is longer than lambda/4 for the dominant harmonics in the pulse waves. Harmonic analysis of the pulse waves recorded from the elastic tube and from two human volunteers also show that phase velocities oscillate with increasing amplitude as reflection increases.