DESPITE the remarkable advances in cardiac surgery, a suitable operation for the correction of all pathological types of mitral regurgitation has not yet been established. Many ingenious blind techniques have been devised and enthusiastically advocated for the surgical correction of mitral regurgitation in the recent past (Bailey, Jamison, Bakst, Bolton, Nichols, and Geminhardt, 1954;Blalock and Johns, 1954;Davila, The mitral valve is a flat cone (Van Der Spuy, 1958). This cone has as its base the mitral annulus, on which hinge the two cusps which form the sides of the cone. As the anteromedial half of the mitral annulus is closely related to the posterolateral half of the aortic root and the corresponding two aortic cusps, it is thus biconcave. The anteromedial mitral cusp, being hinged in this position, forms an integral Glover, Trout, Mansure, Waad, Janton, and Ioia, 1955; and Kuykendall, Ellis, and Grindlay, 1958), but success was invariably transitory and such operations were short-lived. The trend is now towards surgical treatment of mitral regurgitation by open heart surgery. Surely an intelligent attempt at correction can be made only when the valve is adequately visualized and the various pathological factors appraised, evaluated, and corrected under direct vision, employing a mechanical pump oxygenator ?Before attempting the correction of mitral regurgitation, the surgeon should acquire a clear, three-dimensional concept of the anatomy of the mitral valve region, a sound knowledge of the normal mechanism of mitral valve closure, and also the lesions which may cause the derangement of this mechanism.Anatomy of the Mitral Valve.-Anatomically, the mitral valve mechanism consists of four main parts: the annulus fibrosus, the valve leaflets, the chorde tendinee, and the papillary muscles. It is not within the scope of this paper to discuss the anatomy in detail, but certain observations which concern surgery in this region must be mentioned.
