Mitral stenosis

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Dr. Gilbert H. Mudge: Mitral stenosis is one of the most common and most important results of rheumatic fever. Although a comprehensive discussion of the problem must include the cause and prevention of the underlying disease, this clinic has focused attention on the hemodynamic aspects of stenosis as a basis for considering the newer methods of surgical therapy. The action of the valve itself has been studied by direct visualization in experimental animals. This ingenious technic has permitted accurate description of the behavior of the valve throughout the cardiac cycle. Closure of the valve consists of two components: first, a muscular contraction of the ring which greatly reduces the aperture, and second, closure of the valve leaflets. The special significance of the large aortic leaflet is discussed. The hemodynamic sequelae of mitral stenosis are described in an attempt to correlate the functional abnormalities with important clinical features such as dyspnea, hemoptysis and arrhythmias. Cardiac function has been studied under different conditions of exercise, heart rate and cardiac rhythm; it can be analyzed in terms of at least three major factors, the valvular deformity, changes in the pulmonary vascular bed and the myocardial reserve of both sides of the heart. The importance of the muscular component is illustrated by the hemodynamic changes resulting from digitalization and from acute myocarditis. Physiologic effects of stenosis and insufficiency are so complex that it is often difficult to correlate symptoms with function. Since the success of surgical correction eventually depends on such a correlation, it is important to continue to follow patients by precise physiologic methods. The indications and contraindications for the surgical correction of mitral stenosis are considered, with recognition of both the tentative nature of present data as well as the benign nature of the lesion in the vast majority of patients. Rheumatic activity must be considered a major contraindication to surgery. The technical aspects of commissurotomy are discussed in relation to the structure and function of both the normal and diseased valve leaflets. Since acute mitral insufficiency is very poorly tolerated, the modern operation for correcting stenosis has been so devised that the baffle action of the large aortic leaflet is preserved, thus producing a “selective” mitral insufficiency. Problems of pre- and postoperative management are discussed, as are the acute circulatory changes which occur during the surgical procedure. Results of commissurotomy appear promising although longer periods of follow-up are needed for final evaluation.