Pulsatility index as a diagnostic parameter of reciprocating wall shear stress 2 parameters in physiological pulsating waveforms

TL;DR

This study demonstrates that incorporating the pulsatility index with heart rate and flow rate improves the prediction of wall shear stress parameters in pulsating arterial flows, aiding in better diagnosis of arterial pathologies.

Contribution

The paper introduces the pulsatility index as an essential third parameter to enhance the prediction of reciprocating wall shear stress in pulsating flow waveforms, validated through simulation and experimental data.

Findings

PI improves prediction of negative WSS, OSI, and min/max shear stress ratios.

Using PI alongside HR and Q yields better correlation with WSS parameters.

Experimental validation confirms simulation results.

Abstract

Arterial wall shear stress (WSS) parameters are widely used for prediction of the initiation and development of atherosclerosis and arterial pathologies. Traditional clinical evaluation of arterial condition relies on correlations of WSS parameters with average flow rate (Q) and heart rate (HR) measurements. We show that for pulsating flow waveforms in a straight tube with flow reversals that lead to significant reciprocating WSS, the measurements of HR and Q are not sufficient for prediction of WSS parameters. Therefore, we suggest adding a third quantity - known as the pulsatility index (PI) - which is defined as the peak-to-peak flow rate amplitude normalized by Q. We examine several pulsating flow waveforms with and without flow reversals using a simulation of a Womersley model in a straight rigid tube and validate the simulations through experimental study using particle image velocimetry (PIV). The results indicate that clinically relevant WSS parameters such as the percentage of negative WSS (P[%]), oscillating shear index (OSI) and the ratio of minimum to maximum shear stress rates (min/max), are better predicted when the PI is used in conjunction with HR and Q. Therefore, we propose to use PI as an additional and essential diagnostic quantity for improved predictability of the reciprocating WSS.