The invention provides vascular access methods, systems and devices facilitating long-term, repeated, percutaneous access to a patient's blood stream. This is provided by an access tube apparatus adapted for anastomosis to the sidewall of a target anatomical vessel. The access tube has a replaceable occluder that fits within the conduit of the access tube in between blood treatments or when vascular access is otherwise not needed. When such access is desired, the percutaneously accessible occluder is simply removed from the access tube.