An electrical caliper for measurement of pulsatile arterial diameter changes in vivo.

Abstract

The measurement of dynamic elasticity and wall viscosity of living arteries requires a sensitive technique which does not unduly disturb the vessel within its surroundings. Electrical calipers have been developed which record pulsatile changes in arterial diameter varying from 1.5 mm to 5[mu]. These instruments have been shown to have an amplitude response flat to + -5% to 20 cyles/sec and also to exhibit negligible phase distortion; drift was approximately 1% of the normal pulsatile signal. Loading of the vessel was shown to be insignificant. Fourier analysis of a consecutive series of waves from the femoral artery of a dog demonstrated excellent reproducibility of both the pressurediameter ratio and the phase difference of the first 5-corresponding harmonic terms.