12 for insertion into the circulatory system of a living body extending upward from the conduit 12 is an upright structure 14 that will extend through the skin when the device is implanted in a living body and through which access to the conduit 12 is gained to aid description 34 lower 34 or 34 downward 34 are used herein to denote the direction toward the interior of the body while 34 upper 34 or 34 upward 34 are used to describe the direction toward the exterior of the body the conduit 12 of the percutaneous access device 10 is generally cylindrical in shape and has a smooth cylindrical central passageway 15 for unhindered flow therethrough the conduit 12 can be inserted in line with a blood vessel by means of any of the well known techniques with ridges 16 on the exterior of the conduit 12 providing for a more secure attachment between the blood vessel and the conduit the valve body 10 should be strong and durable and its surfaces should be biocompatible and thromboresistant accordingly the valve body 11 may be made of metals such as titanium stainless steel or chromium cobalt alloys or the surfaces of the valve body 11 may be made biocompatible and thromboresistant by coating them with carbon by vapor deposition as described in u s pat no 3 952 336 issued apr 27 1976 to bokros et al in accordance with the invention the valve housing 11 is provided with at least one pair of intersecting passages and a cooperating plunger to provide access to the central passageway 15 of the conduit 12 from the region exterior of the body upon selective withdrawal of the plunger with reference to the illustrated embodiment which is particularly suited for use in.