* The mitral valve is the most commonly and severely affected valve in chronic rheumatic disease. * Chronic rheumatic valvulitis is characterized by irregular thickening and calcification of the leaflets, with fusion of the commissures and chordae tendineae -the valve orifice becomes reduced to a "fish mouth" or "buttonhole"stenosis *The pressure in the left atrium rises and is transmitted the pulmonary veins to the pulmonary vasculature. -Image shows Rheumatic vegetation on mitral valve in chronic rheumatic disease -Image shows "fish mouth" or "buttonhole"stenosis * In cases of aoic insufficiency or stenosis, the left atrium is initially protected by closure of the mitral valve. The other choices are not associated with atrial enlargement or pulmonary edema.