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 (nDs) 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 (Dsd) and Tangential Elastic Modulus (Em). In flexible tubes, the average nDs was higher and nE was lower than Dsd and Em by 1.6% and 6.9%, respectively. In calf aortas, the results of nDs and nE agreed well with those of Dsd and Em, as demonstrated by Bland-Altman technique. The results of nDs and nE are comparable to those determined using traditional techniques. Our results suggest that nDs 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.