Patients with end stage renal disease are at 18-20 times greater risk of dying from cardiovascular disease as the general population. Both traditional and non-traditional cardiovascular risk factors are thought to be important. Of the non-tradtional cardiovascular risk factors, creation of an arteriovenous fistula or graft for the purposes of a blood access for hemodialysis may contribute to an elevation in BNP and left ventricular hypertrophy - both factors that have been associated with an increased risk of mortality Prior to access creation and at one month and one year post access creation - samples for BNP will be collected Prior to access creation and at one year post access creation - echocardiography will be performed