 This a randomised controlled study to evaluate the effect of Iliac arterio-venous anastamosis in patients with neurally mediated syncope. The Head up tilt test is used as an objective measure to evaluate the effect of the arterio-venous anastamosis in patients with NMS. Participants with tilt test proven NMS will be eligible for the study if they satisfy all other eligibility criteria. Participants will be randomised to ROX coupler intervention or standard therapy. The primary outcome measure will be absence of loss consciousness on tilt table testing at 3 months post intervention. 