Silent mitral regurgitation.

The occurrence of significant mitral regurgitation whithout the characteristic auscultatory signs, particularly the holosystolic murmur and the third heart sound, is unusual. It becomes of considerable importance when it occurs in combined lesions of the mitral valve, and more so in those areas where the treatment of mitral stenosis is by closed mitral valvotomy. Two cases of silent mitral incompetence are presented. The features that should have indicated the coexistence of regurgitation with mitral stenosis were cardiomegaly with considerable dilatation of the left atrium, and lesser degrees of right ventricular hypertrophy on electrocardiography for the severity of mitral stenosis and evidence of biventricular hypertrophy.