The On-X® Prosthetic Heart Valve is a bileaflet mechanical heart valve, which consists of an orifice housing and two leaflets. The orifice inflow area has a flared inlet designed to reduce flow turbulence, and the outflow rim consists of leaflet guards designed to protect the leaflets while in the closed position. The leaflets rotate around tabs located within the inner circumference of the orifice ring. In the closed position, each leaflet forms a nominal angle of 40º relative to the plane of the orifice. In the open position, the plane of each leaflet forms a nominal angle of 90deg relative to the plane of the orifice. The leaflets have a travel arc of 50deg to the closed position. The orifice, or housing, is composed of a graphite substrate coated with On-X® Carbon, a pure unalloyed form of pyrolytic carbon. The leaflets consist of On-X® Carbon deposited on a graphite substrate, which is impregnated with 10 weight% tungsten to provide radiopacity. The sewing cuff is constructed of polytetrafluoroethylene (PTFE) fabric mounted on the orifice using titanium retaining rings and 5-0 suture material. This form of sewing cuff attachment to the orifice allows for rotation of the sewing cuff in situ during implantation. Orientation reference marks are provided on the sewing cuff for valve orientation. The On-X® Prosthetic Heart Valve is available in 3 aortic and 2 mitral sewing cuff configurations. Aortic configurations are available in sizes 19, 21, 23, 25, and 27/29 mm. The standard mitral cuff is available in sizes 23, 25, 27/29 and 31/33, while the Conform-X® mitral cuff is available in size 25/33 only. Further detail for the On-X prosthetic heart valve is described in the Summary of Safety and Effectiveness documents for the On-X heart valves: http://www.accessdata.fda.gov/cdrh_docs/pdf/P000037b.pdf (aortic), and http://www.accessdata.fda.gov/cdrh_docs/pdf/P000037S001b.pdf (mitral).
A sterile artificial substitute for a natural aortic heart valve intended to be implanted during open heart surgery typically to treat acquired or congenital valvular disease. It consists of two flat, semicircular, pyrolytic carbon-coated or polymer leaflets that pivot about pyrolytic carbon or metal struts attached to the valve housing by hinges; the hinge points intersect the valve lumen resulting in a total of three openings. When pressurized blood hits the valve, the two halves of the circle fold away from the valve ring and allow blood to flow into the three openings before the valve flaps close again.