Medical valve apparatus

A medical valve placed in a tubular duct of at least one of an artificial heart device and an artificial heart-lung device capable of passing a first flow of a liquid but interrupting a second flow which flows in an opposite direction to the first flow, the medical valve comprising:

• a substantially circular valve seat, having a substantially flat surface, provided in the tubular duct, having the valve-seat surface at one side of said valve seat, said valve-seat surface being located at a downstream side of the first flow, said valve seat further having a plurality of small through holes substantially evenly allocated thereupon except for a central part thereof;
• and
• a flexible flap provided solely at the downstream side of the valve seat and having a surface area slightly smaller than that of the circular valve seat in a manner such that the flexible flap covers all the plurality of small through holes, the flexible flap being fixed to the central part of the valve-seat surface, wherein a circumferential part of the flexible flap moves apart from the valve-seat surface so as to pass the first flow while the circumferential part sealingly adheres to the valve-seat surface so as to interrupt the second flow, wherein the flexible flap is made of a copolymer film which is comprised of polyurethane and polysiloxane and has a thickness of 0.1 to 0.4 mm said copolymer film having at least anti-thrombogenic properties for the passage of blood.