A self-sealing, penetrable, hemostasis valve for a catheter introducer or the like which comprises an elastomeric gasket member having first and second opposed faces adapted to be secured in a valve housing, wherein faces define generally concave surfaces to reduce the central thickness of the gasket...http://www.google.es/patents/US5125903?utm_source=gb-gplus-sharePatente US5125903 - Hemostasis valve
