The Influence of Experimental Condition on the Derivation of Propagation Coefficient in Arterials Systems: Numerical Investigation

Abstract

Over the last few decades several methods have been used to compute the propagation coefficient, which is a complex number that provides information about the viscoelastic properties of blood vessels. Results from these methods show a considerable disparity between them and when they are compared to theoretical values. Moreover, the attenuation and phase velocity obtained by the three-point method shows more significant discrepancies than those obtained by the other methods. In order to clarify the source of the disparity of results carried out by various methods concerning the estimation of phase velocity and attenuation in the arterial network, we made investigations using numerical tool several methods. We studied, for each method, the effects of distance between measurement sites, the sampling interval and measurement errors on the determination of the propagation coefficient by each of these methods. The values of wave speed and attenuation computed by these methods were compared to the known input values. Our simulation demonstrates that the distance between measurement sites and the sampling interval may introduce significant errors when the noise becomes high. Moreover the error on the values of attenuation and phase velocity obtained by occlusion and three-point methods is significantly higher than the error on the values obtained by RV-I and RV-II methods for all experimental conditions studied within the examined frequency range. This result supports the idea that the discrepancy between studies reported in literature seems to be due to the inaccuracy of experimental measurement techniques and not associated with the methods themselves as concluded by some authors.