An implantable device grafted directly to vascular structures for high volume blood and/or fluid infusion and/or removal for such purpose as hemodialysis, apheresis, exchange transfusion, or large volume fluid infusion. The device is also adaptable to intermittent access to the venous or arterial circulations for purpose of blood sampling or giving medications. The device is comprised of an implantable fluid chamber connected to a cannula or shunt segment which is then grafted directly to the vascular structure (e.g. artery or vein) using a sewable cuff located at the vascular end of the cannula or shunt segment. The vascular end of the device employs a valve which is directly adjacent to the vascular structure after grafting, in order to prevent reflux of blood and subsequent washout of anticoagulant during periods when the device is not in use. The device is accessed percutaneously with a needle or needle-introduced catheter and is filled with anti-coagulant prior to needle withdrawal to prevent thrombosis.