Mechanical Impedance of the Dog's Hind Leg to Pulsatile Blood Flow

Abstract

Femoral arterial pressure and flow were recorded with apparatus capable of following cyclic changes at frequencies greater than those encountered. The records were subjected to Fourier analysis, and impedance magnitude and phase angle relations were computed at various frequencies. The impedance curve showed a dip at 180 cpm and a subsequent rise at higher frequencies, suggesting a resonant system. This suggestion was corroborated by the phase angle curve, which crossed from elastance controlled to inertia controlled behavior at 180 cpm. A simple physical model is suggested which contains some of the frequency characteristics of the vascular system studied. From this model rough values of compliance and inertance were computed.