The present invention relates to subcutaneously implanted graft-port systems, devices and methods for establishing access to the vascular system of a patient requiring multiple blood treatments over an extended period of time. The systems, devices and methods disclosed herein reduce miscannulation, promote intra-session hemostasis, and decrease the incidence of bacteremia and sepsis among other improvements and advantages. The devices include a port with a flattened plateau-like surface for receiving an access tube. The flat surface may include a tactile or visual guide to assist with placement of the access tube into the tapered seat. Optional valve mechanisms reduce the size and form factor of the implantable graft-port device and seals the conduit of the port closed to physiologic pressures until the valve is opened upon percutaneous insertion of the access tube. The access tube does not pass into the conduit. A mismatch fit between the access tube and tapered seat causes a decrease in the cross-sectional sealing area, a reduction in the overall device size, and an increase in blood flow during treatment. Lock solutions to prevent fowling and infection are also disclosed.
