An improved mitral valve prosthesis

A Dacron velour–covered, Teflon-disc mitral valve prosthesis was developed in an effort to reduce thromboembolic complications of mitral valve replacement. A 12- to 28-month follow-up of 202 patients receiving these prostheses demonstrated only a 4.5% total incidence of such complications. However, a continuing search has been made for more durable materials. The most promising of these has been Pyrolite carbon, which now has been used for both the disc and the struts. Sacrifice of calves at intervals up to 12 months with scanning electron microscopical studies has demonstrated a disc and strut wear curve projecting 140 years prior to penetration of the Pyrolite carbon coating. Orifice and frustum areas of all sizes have been enlarged without change in mounting diameter. Clinical investigations of this prosthesis in several centers have been associated with as low an incidence of thromboembolic complications as that achieved with the Teflon-disc prosthesis. This improved prosthesis now has been released for general use.