The majority of bridge graft fistula with polytetrafluoroethylene (PTFE) for hemodialysis access will develop stenosis at the venous anastomosis and eventually will fail. Aspirin have been used for many years as a prophylactic drug therapy to prevent thrombosis but good clinical evidence for its benefit is lacking. Many drugs have been used to reduce intimal hyperplasia in animal models. Until recently there has been little success in clinical trials of anti-inflammatory, antiproliferative, antiplatelet, antithrombotic or calcium channel blocking drugs. Recently a major breakthrough was done by GORE when introducing the new heparin bonded PTFE graft by covalent attachment. This trial is planed to assess and compare between the GORE-TEX® PROPATEN vascular graft versus unmodified ePTFE grafts the patency and complication.