Purpose: Pulse wave velocity (PWV) is an indicator of arterial stiffness used in the prediction of cardiovascular disease such as atherosclerosis. Non-invasive methods performed with ultrasound probes allow one to compute PWV and aortic stiffness through the measurement of the aortic diameter (D) and blood flow velocity (U) with the lnD-U method. This technique based on in vivo acquisitions lacks validation since the aortic elasticity modulus cannot be verified with mechanical strength tests.
Method: In the present study, an alternative validation is carried out on an aorta phantom hosted in an aortic flow simulator which mimics pulsatile inflow conditions. This in vitro setup included a Particle Image Velocimetry device to visualize flow in a 2D longitudinal section of the phantom, compute velocity fields (U), and track wall displacements in the aorta phantom to measure the apparent diameter (AD) variations throughout cycles.
Results: The lnD-U method was then applied to evaluate PWV (5.79 ± 0.33 m/s) and calculate the Young's modulus of the aorta phantom (0.56 ± 0.12 MPa). This last value was compared to the elasticity modulus (0.53 ± 0.07 MPa) evaluated with tensile strength tests on samples cut from the silicone phantom.
Conclusion: The PIV technique PWV measurement showed good agreement with the direct tensile test method with a 5.6% difference in Young's modulus. Considering the uncertainties from the two methods, the measured elasticities are consistent and close to a 50-60 years old male aortic behavior. The choice of silicone for the phantom material is a relevant and promising option to mimic the human aorta on in vitro systems.
Keywords: Aorta; Circulatory mock loop; Particle Image Velocimetry; Phantom; Pulse wave velocity.
© 2022. The Author(s) under exclusive licence to Biomedical Engineering Society.