Hemostasis valve having support shoulders

A hemostasis cannula unit comprising:

• (a) a longitudinally extended valve housing having a first opening and a central longitudinal chamber communicating with an opposite second opening;
• (b) a cap means enclosing the first opening of the valve housing and providing a hole to permit the insertion of a catheter into the housing's first opening through the central chamber and out the opposite second opening;
• and
• (c) a one-piece seal means stationarily located within said central chamber and having a conical receiving area tapered into a sealing neck and communicating with said hole in said cap means, said sealing neck further communicating with a sealing chamber having sealing exit lips, wherein said seal means has support shoulders on an outside surface of said seal means adjacent to the sealing neck, wherein said support shoulders are not greater in diameter than the widest portion of the sealing chamber, and wherein the widest portion of said sealing chamber has an outside diameter less than that of said valve housing such that an annular spacing is defined between said sealing chamber and interior walls of said valve housing, said annular spacing being maintained when a catheter is inserted into said seal means and wherein said sealing exit lips are formed of at least a pair of opposing normally closed lips.