Mitral Valve Surgery

Abstract

Today, there are a multitude of prosthetic valves available for mitral valve replacement. These can generally be divided into bioprosthetics and mechanical valves. Of the mechanical valves. the StarrEdwards valve has been employed since the early 1960’s. and the current valve model has not changed or been modified since 1966 (Fig.1a). Valve failure since that period of time is virtually unheard of. and the valve remains the gold standard against which durability can be compared. This valve has an unfavorable internal diameter-toexternal diameter ratio. especially in the small sizes. as we will later discuss. and. therefore. may contribute to unfavorable gradients. The other class of mechanical valves are the tilting disc varieties. These include the st. Jude (Figure 1b). the Omni-Science (Figure 1c). the Medtronic-Hall (Figure 1d). and the Duramedic valve among others. The majority of these valves had their inception between 1977 and 1981. and all incorporate the use of ferropyrolite to reduce thromboembolic incidents and decrease valve wear. An infrequent complication of tilting disc valves. and one that usually occurs in the presence of inadequate coagulation. is valve thrombOSiS. This process is due to defibrinogenation of the blood. and the incidence is probably proportional to the number of struts through which blood must pass.