Modification of the Smeloff mitral prosthesis.

The simplicity of the ball valve with its random seating capabilities coupled with its durability, reliability, and predictability has made it the attractive choice of many surgeons. A low incidence of embolic phenomena with the Smeloff full-orifice, double-caged, bare-strutted ball valve has made us reluctant to alter the design over 17 years. Recent evaluation of the reasons for reoperation on the Smeloff mitral valve implantation in 376 cases revealed 16 cases in which development of fibrous subvalvular pannus with signs and symptoms of mitral stenosis occurred. The mean occurrence time was 7.5 years for adults and 4.6 years for children under age 8 years. No such problem has been encountered with the valve in the aortic position. Many of these patients are maintained on aspirin and Persantine alone. Valve design was explored as a possible cause of mitral subvalvular stenosis. Alterations of the design were examined in the engineering laboratory and in dog implantations by catheterization, electrophysiologic evaluation, and echocardiography. The results were encouraging.

Development of a cardiac valve substitute: the Smeloff-Cutter prosthesis.

Several criteria were used for the development of the Smeloff-Cutter prosthesis: (a) the valve must permit adequate pulsatile forward flow with minimal gradients and regurgitation; (b) materials used must be inert or compatible with tissue and blood; (c) the prosthesis must be durable; (d) attachment must be easy and secure; (e) the valve must be nonhemolytic and nonthrombogenic; (f) its geometry must not impinge on surrounding structures; (g) testing must be in vitro as well as in vivo; and (h) its use must result in an acceptable long-term clinical response. Application of these criteria to the design of the Smeloff-Cutter valve is described.