 Neurally mediated syncope NMS is a debilitating condition, with no proven therapeutic measures. The ROX coupler is a device used to create an Iliac arterio-venous anastamosis which allows a shunt of 0.8 litres per minute. The haemodynamic changes following creation of an arterio-venous anastomosis at the iliac level leads to an increase in cardiac preload, reversing finding thought to induce NMS. 