An access port comprises a base and a flexible conduit. The port is subcutaneously implanted and the conduit is attached directly or indirectly to a blood vessel or other body lumen or cavity. An actuator mechanism is provided with a linkage which opens a valve in the port in response to percutaneous insertion of a needle into the access port. In particular, insertion of the needle opens the clamping mechanism to permit flow through the conduit between the blood vessel and the needle.
