Towards the non-invasive determination of arterial wall distensible properties: New approach using old formulae

Arterial function and wall mechanical properties are important determinants of hemodynamics in the circulation. However, their non-invasive determination is not widely available. Therefore, the aim of this work is to present a novel approach for the non-invasive determination of vessel's distensibility and elastic modulus. Simultaneous measurements of vessel's Diameter (D) and flow velocity (U) were recorded to determine local wave speed (_nC) in flexible tubes and calf aortas non-invasively using the lnDU-loop method, which was used to calculate the Distensibility (_nD_s) and Elastic Modulus (_nE), also non-invasively. To validate the new approach, the non-invasive results were compared to traditionally invasive measurements of Dynamic Distensibility (D_sd) and Tangential Elastic Modulus (E_m). In flexible tubes, the average _nD_s was higher and _nE was lower than D_sd and E_m by 1.6% and 6.9%, respectively. In calf aortas, the results of _nD_s and _nE agreed well with those of D_sd and E_m, as demonstrated by Bland-Altman technique. The results of _nD_s and _nE are comparable to those determined using traditional techniques. Our results suggest that _nD_s and _nE could be measured in-vivo non-invasively, given the possibility of measuring D and U to obtain _nC. Further studies are warranted to establish the clinical usefulness of the new approach.