The area of the pressure – flow loop for assessment of arterial stenosis: A new index

Abstract

This study describes a novel method for assessing stenotic severity, based on simultaneous pressure and flow wave measurements. Pressure and flow measurements were performed in latex and rubber tubes, and in a clinically-used vascular graft. Pressure waves were recorded at several degrees of stenosis and at different distances proximal to the stenosis. Pressure wave versus flow wave was plotted. Internal pressure-flow loop area (PFLA), loop slope and pressure-axis intercept were calculated. Values of these three indices significantly increased with increasing degrees of stenosis $\mathit{P}\mathrm{<}0.001$ ). Similar phenomenon was observed during in-vivo experiments. Polynomial functions were fitted, resulting in an excellent PFLA variable/percent stenosis correlation, independent of distance between sensor and stenosis ( ${\mathit{R}}^2\mathrm{>}0.96$ ). In addition, tube compliance was measured and found to correlate with the polynomial coefficients ( $|\mathit{R}|\mathrm{>}0.9$ ). This innovative approach could significantly contribute to detecting and evaluating arterial stenoses, and to characterize the elasticity of the artery.