Structural deformities of cardiac valves are the usual accompaniment of rheumatic fever. The lesion most commonly produced by rheumatic carditis is stenosis of the mitral valve. The deleterious effect of this lesion on the pulmonary circulation and the right side of the heart leads in a considerable proportion of cases to eventual cardiac decompensation and death. The idea of correcting the stenosis by direct incision was entertained by many clinicians, but it was only recently that the newly acquired experience in cardiac surgery made it possible to invade the cardiac chambers and correct the existing valvular deformity. The technical problem in treating mitral stenosis was that of relieving the stenosis without the production of significant regurgitation.
One of the important problems confronting the surgeon about to perform a mitral commissurotomy is the question of whether the rheumatic infection in a given case has completely subsided. The possibility of reactivating a