P134 A COMPUTATIONAL INVESTIGATION OF CONFOUNDING FACTORS AFFECTING FLOW MEDIATED DILATION: TOWARDS IMPROVED ENDOTHELIAL FUNCTION ASSESSMENT

Abstract

Objective and motivation: Endothelial dysfunction is associated with cardiovascular diseases. Flow mediated dilation (FMD), assesses the endothelial function by measuring the brachial artery vasodilation following deflation of a sphygmomanometer cuff around the forearm. Vasodilation is assumed to be due to an increase in wall shear stress (WSS) only. However, there is evidence that the vasodilation may be affected by other confounding factors1. We aim to investigate the effects of confounding factors on the results of FMD. Methods: A dynamic simulation of FMD was carried out using a one-dimensional haemodynamic solver of blood flow in the arm arterial vasculature (Fig. 1a) 2. Haemodynamics during cuff deflation was simulated by prescribing a decrease in peripheral resistance (Fig. 1b) in a novel mathematical model which dynamically couples increasing WSS (Fig. 1c) to decreasing arterial wall Young’s modulus (Fig. 1d), taking into account endothelial function. Results: Our results show that the initial increase in flow velocity (Fig. 1e) is caused by the prescribed decrease in peripheral resistance and leads to an initial pressure drop affecting the FMD value. WSS induces a drop in Young’s modulus leading to vasodilation (Fig. 1f). In addition, for the same prescribed endothelial function (relating WSS to Young’s modulus variation) and decreased peripheral resistance, FMD increases with decreasing arterial stiffness (3.17% vs 5.31% vs 8.56% (Fig. 1f)). ConclusionOur numerical model successfully described FMD haemodynamics and highlighted one of the important confounding factors of FMD values: arterial stiffness. We are currently investigating other factors and ways of correcting those factors.