Function of expanded-polytetrafluoroethylene laminated trileaflet valves in animals

A stent-mounted trileaflet cardiac valve prosthesis has been developed in which the valve leaflets were fabricated from 0.003-mm films of expanded polytetrafluoroethylene laminated in 4 to 15 layers. A total of 28 valves of varying leaflet thickness were implanted in the tricuspid position in dogs. Cardiac catheterization performed during the follow-up period between 1 week and 15 months after valve replacement in 20 surviving animals showed that the initial good function was maintained in 12 dogs for up to 15 months, whereas valve dysfunction developed in 8 other dogs within 6 months. Autopsy revealed that the cause of valve dysfunction among the eight dogs was cusp stiffening with or without retraction in six, dehiscence of the suture ring in one, and strut entrapment in one. This study demonstrated that the thickness of the leaflet material is an important factor affecting the long-term function in vivo.