A medical device, assembly and system

An apparatus 1 for subcutaneous implantation is disclosed. The apparatus comprises a port 40 for receiving a percutaneous connector 55, the port comprising an electrical contact 43 for providing electrical communication between the port and the connector. The port may further comprise a recess 41 with a septum 44 which may be pierced by the connector. The septum may also have a locking mechanism for retaining the connector. An RFID chip may be located proximate the recess for identifying the location of the port. Also disclosed is a percutaneous connector for engaging a subcutaneously implanted port, an implantable control unit 1 for a medical device 60 (Figure 6), a cardiac pump assembly 70 (Figure 7) and an extracorporeal charging device 80 (Figure 8).