Mitral valve stenosis

Mitral stenosis (MS) is a valvular anomaly of the mitral valve that leads to obstruction of blood flow into the left ventricle. The most common cause of MS is rheumatic fever. The clinical manifestations depend on the extent of stenosis: reduced mitral opening leads to progressive congestion behind the stenotic valve. Initial dilation of the left atrium (complications: atrial fibrillations, emboli) is followed by progressive congestion of the lungs and subsequent cardiac asthma (coughing, dyspnea). Acute decompensation can cause pulmonary edema. Echocardiography is the main diagnostic tool for evaluating the mitral valve apparatus, left atrial size, and pulmonary pressure. In the event of high grade and/or symptomatic stenosis, percutaneous valvuloplasty or surgical valve replacement is often required.

• Most commonly due to rheumatic fever
• Autoimmune diseases: systemic lupus erythematosus, rheumatoid arthritis
• Congenital
• Some conditions may mimic mitral stenosis: bacterial endocarditis of the mitral valve with large vegetation, left atrial myxoma
• Degenerative aortic stenosis

• Mitral valve stenosis → obstruction of blood flow into the left ventricle (LV) → limited diastolic filling of the LV (↓ end-diastolic LV volume) → decreased stroke volume → decreased cardiac output (forward heart failure)
• Mitral valve stenosis → increase in left atrial pressure → backup of blood into lungs → increased pulmonary capillary pressure → cardiogenic pulmonary edema → pulmonary hypertension → backward heart failure and right ventricular hypertrophy

• Initially asymptomatic; (onset ∼ 10 years after acute rheumatic carditis)
• Dyspnea (paroxysmal nocturnal dyspnea) and orthopnea, especially when supine
• Hemoptysis
• Hoarseness
• Dysphagia
• Mitral facies
• Atrial fibrillation and embolic complications
• Later stages: signs and symptoms of right-sided heart failure

References:^[1][2][3]

• Auscultation (see auscultation in valvular defects)
  • Diastolic murmur typically heard best at the 5^th left intercostal space at the mid-clavicular line (the apex)
    • Heard loudest when the patient is lying on his/her left side.
  • Loud first heart sound (S₁)
  • Opening snap of the mitral valve after S₂: A high frequency, early-to-mid diastolic sound that occurs when leaflet motion suddenly stops during diastole after the stenosed valve has reached its maximum opening
  • Shorter interval between S₂ and opening snap is indicative of more severe disease; , because left atrial pressure is greater than left ventricular end-diastolic pressure (LVEDP).
• X-ray chest
  • Posterior-anterior image
    • LA enlargement with prominent left auricle (left atrial appendage) → straightening of the left cardiac border
    • Signs of pulmonary congestion; (see “X-ray findings in pulmonary congestion”)
  • Lateral image
    • Dorsal displacement of the esophagus (visible in barium swallow test)
    • Signs of right ventricular hypertrophy
• ECG
  • P mitrale
  • Atrial fibrillation
  • Signs of right ventricular hypertrophy (Sokolow-Lyon index)
• Echocardiography: most important diagnostic method for detecting and assessing valvular abnormalities
  • Assess the mitral valve structure, function, and stenosis severity
    • Leaflet thickening and rigidity
    • Calcification
    • Subvalvular thickening
    • Decreased mitral valve area (MVA): ≤ 1.5 cm² is considered to be severe MS.
  • Assess for left atrial thrombus and concomitant mitral regurgitation.
• Coronary angiography may be conducted prior to surgical interventions to assess the risk of associated coronary artery disease

References:^[2][3][4]

• Conservative treatment
  • Treatment of heart failure: only diuretics may be administered!
  • Beta blockers or calcium channel blockers: ↓ heart rate and ↓ cardiac output
  • Endocarditis prophylaxis in high-risk cases e.g., history of IE, prosthetic valve (see “Infective endocarditis”)
• Interventional
  • Indication: severe (MVA ≤ 1.5 cm²) and/or symptomatic mitral stenosis
  • First-line: percutaneous balloon commissurotomy of the mitral valve (PMBC) if the following criteria are fulfilled:
    • Favorable valve morphology e.g., no valvulvar calcifications
    • No left atrial thrombus
    • No or mild mitral regurgitation
  • Alternatives: open commissurotomy and surgical valve replacement (mechanical prosthetic valve or biological prosthetic valve)

ACE inhibitors and other afterload-reducing drugs are contraindicated because they cause dilation of peripheral blood vessels, which may lead to cardiovascular decompensation!

• Atrial fibrillation → thromboembolic events
• Progressive congestion of the lungs, pulmonary edema, pulmonary hypertension
• Congestive heart failure
• Enlarged left atrium (rare) → esophageal compression; , recurrent laryngeal nerve palsy

We list the most important complications. The selection is not exhaustive.

1. Jenkins B, McInnis M, Lewis C. Step-Up to USMLE Step 2 CK. Lippincott Williams & Wilkins ; 2015
2. Mitral Valve Disease: Stenosis and Regurgitation. http://www.clevelandclinicmeded.com/medicalpubs/diseasemanagement/cardiology/mitral-valve-disease/. Updated: August 1, 2014. Accessed: February 13, 2017.
3. Dima C. Mitral Stenosis. Mitral Stenosis. New York, NY: WebMD. http://emedicine.medscape.com/article/155724-overview. Updated: November 6, 2014. Accessed: February 26, 2017.
4. Nishimura RA, Otto CM, Bonow RO, et al. 2014 AHA/ACC guideline for the management of patients with valvular heart disease: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines. J Am Coll Cardiol. 2014; 63 (22): p.e57-185. doi: 10.1016/j.jacc.2014.02.536 . | Open in Read by QxMD
5. Herold G. Internal Medicine. Herold G ; 2014