Pulse Wave Velocity Calculation in an Elastic U-Shaped Tube Using Computational Fluid Dynamics (CFD)
Introduction: Arterial stiffness is associated with cardiovascular mortality and can be non-invasively assessed by the estimation of pulse wave velocity (PWV). PWV is a surrogate of arterial stiffness, involving the vessel elasticity, geometry and wall thickness. Complex blood flow patterns, such as those found in the ascending or proximal descending aorta, might affect the PWV calculation. The aim of this work was to estimate PWV in a CFD simulation of an idealized aorta under several geometric and elastic configurations and to compare the obtained values to those predicted theoretically by the Moens-Korteweg (M-K) equation.
Methods: We simulated a Newtonian fluid circulating through a U-shaped elastic tube under a pulsatile flow regime. PWV was calculated by computing the peak pressure at several cross-sectional planes along the tube and estimating the transit-time (TT) among the waveforms. PWV was defined as the slope of the TT vs distance linear regression. Different values of Young’s modulus, diameter and wall thickness of the tube were tested.
Results: Simulated PWV systematically overestimated theoretical PWV by 12%. As predicted by M-K, the PWV was proportional to the vessel elasticity and wall thickness and inversely related to the tube diameter. Percentage changes of 10% in the tube elasticity, wall thickness and diameter modified the VOP by ~5%.
Conclusion: We verified the dependence of PWV in the M-K equation parameters in a CFD model and its value was overestimated by 12% in all cases. CFD can be a powerful tool analyze PWV in idealized geometries of aortas.