Abstract: A replaceable catheter system provides a way to replace an implantable sensor, electrode system, and/or fluid delivery/receiving system. The replaceable catheter system includes an implantable shunt, such as an arteriovenous shunt, attached to an implantable introducer. The introducer and implantable shunt are adapted for surgical implantation within a patient such that it extends from immediately below the patient's skin to the implantable shunt site. The replaceable catheter system further includes a replaceable catheter that is adapted to be contained within the introducer and properly aligned such that an implantable sensor, electrode system, and/or fluid delivery system that is carried by the replaceable catheter is placed in operative association with the implantable shunt and exposed to any fluids passing through the implantable shunt.