The incompetent valves in the majority of patients with mitral regurgitation can be surgically corrected by the technics described above. The ease and effectiveness of the correction are largely dependent upon the severity of the pathologic process. The roles of chronic myocarditis, myocardial failure, pulmonary vascular sclerosis, and the presence of other valvular defects are important factors in the eventual result. Fortunately, the abnormality in the majority of valves can be corrected, and the myocardial reserve is usually sufficient to provide satisfactory function. With continued progress in this field, earlier surgical intervention, and probably less severe disease from improved treatment, better results can be anticipated in the future.