Mitral Stenosis

Key Features

• Underlying rheumatic heart disease in almost all patients (although history of rheumatic fever is often absent)

Clinical Findings

• An opening snap following A₂ due to stiff mitral valve

• Interval between opening snap and aortic closure sound is long when the left atrial pressure is low but shortens as left atrial pressure rises and approaches the aortic diastolic pressure

• Low-pitched rumble at apex with patient in left lateral position, increased by brief exercise

• Moderate stenosis (valve area 1.5–1.0 cm²): exertional dyspnea and fatigue common, especially with tachycardia

• Severe stenosis (valve area < 1.0 cm²): severe pulmonary hypertension develops due to a "secondary stenosis" of the pulmonary vascular bed

• Sudden increase in heart rate may precipitate pulmonary edema

• Paroxysmal or chronic atrial fibrillation develops in ~50–80%, may precipitate dyspnea or pulmonary edema

Diagnosis

• ECG typically shows left atrial abnormality and, often, atrial fibrillation

• Doppler echocardiography confirms diagnosis and quantifies severity by assigning 1–4 points to each of four observed parameters, with 1 being the least involvement and 4 the greatest

  • Mitral leaflet thickening

  • Mitral leaflet mobility

  • Submitral scarring

  • Commissural calcium

• Cardiac catheterization to detect valve, coronary, or myocardial disease, usually done only after a decision to intervene has been made

Treatment

• Control heart rate

• Attempt conversion of atrial fibrillation

• Once atrial fibrillation occurs, provide lifelong anticoagulation with warfarin, even if sinus rhythm is restored

• Intervention to relieve stenosis indicated for symptoms (eg, pulmonary edema, decline in exercise capacity) or evidence of pulmonary hypertension

• Percutaneous balloon valvuloplasty

  • Low mortality rate (< 0.5%)

  • Low morbidity rate (3–5%)

  • Can be repeated if the morphology of the valve remains suitable

  • Not effective when bioprosthetic valve stenosis occurs

• Surgical valve replacement is done in combined stenosis and regurgitation or when the mitral valve is significantly distorted and calcified

• Operative mortality rate is ~1–3%