Mitral valve stenosis

Viewed via the open left atrium is a “fishmouth” mitral valve as a long term sequel of rheumatic fever.

A markedly thickened, stiff mitral valve. Note fusion of leaflets and chordae.  The leaflets are thickened and fibrotic.

Once a common disease, acute rheumatic fever is now rare in developed countries. It is an acute multisystem disease, immunologically mediated. It follows a few weeks after group A alpha-hemolytic streptococcal infection, usually in the pharynx. Rheumatic carditis may be part of the acute process. Acute RF can be fatal but the major problem is that of cardiac sequelae including deforming fibrosis of the cardiac valves, especially the mitral and aortic valves, resulting in permanent dysfunction. The clinical manifestations of the valvular disease may not appear for years or decades when the patient is likely to first note exertional dyspnea, paroxysmal nocturnal dyspnea, and orthopnea. The leaflets or cusps become thickened and retract. This may result in valvular stenosis and/or insufficiency. The mitral or tricuspid valve (less often affected) in chronic RHD shows leaflet thickening and stiffness, fusion of the commissures, and shortening of the chordae. The cords also thicken and fuse. Histologically, fibrosis and neovascularization obscure the architecture of the valve. Aschoff bodies are not seen in chronic RHD unless there has been recent reactivation. Mitral stenosis results in increased left atrial pressure with resultant pulmonary congestion. With time, pulmonary hypertension and subsequent right heart failure may ensue. Besides congestive heart failure, complications of mitral stenosis include infectious endocarditis, formation of left atrial mural thrombi, especially after the onset of atrial fibrillation, with possible peripheral embolization.