More than a decade has passed since the development of modern techniques for the surgical treatment of mitral stenosis. During this relatively brief interval a remarkable experience has been gained in the indications for and the response to surgical intervention. Almost at the outset it was demonstrated that a satisfactory increase in the size of the valve orifice could arrest or reverse the pathophysiological patterns of mitral stenosis. However, it also became quite clear with time, even to the most enthusiastic protagonists, that surgery had important limitations.
Under the restrictions imposed by closed heart techniques, an effective reconstitution of structure and function proved difficult, if not impossible, when extensive calcification and fusion rendered the valve exceptionally distorted and misshapen. The issue was always compounded under these circumstances and even under more favorable ones by the constant hazard of inadvertently creating valvular incompetence. Actually the frequency with which the clinical manifestations of