Appearance of Disease:

The heart has been opened to display an enlarged left atrium, with irregular zones of thickening just above the posterior leaflet of the mitral valve. These thickenings (McCallum plaques) are areas of scarring due to a previous episode of rheumatic fever. The mitral valve leaflets are thickened and distorted by scarring, as are the chords which attach the leaflets to the left ventricle (chordae tendineae). These abnormalities would have caused a failure of both normal opening and normal closure of the mitral valve. The left ventricular muscle is enlarged (hypertrophied) and somewhat dilated.