Mitral Stenosis

The leading cause of mitral stenosis is rheumatic heart disease which has a higher predilection for women than men. The other cause is calcific degenerative mitral stenosis which is unrelated to Rheumatic fever.

Pathophysiology of Mitral stenosis

  • Immune-mediated damage to the mitral valve (due to rheumatic fever) caused by cross-reactivity between the streptococcal antigen and the valve tissue leads to scarring and narrowing of the mitral valve orifice.
  • Mitral stenosis results in elevated left atrial and pulmonary venous pressure leading to pulmonary congestion.
  • Anything that increases flow across the mitral valve (exercise, tachycardia, and so on) exacerbates the pulmonary venous HTN and associated symptoms.
  • Long-standing MS can result in pulmonary HTN and ultimately can result in right ventricular failure (RVF).
  • It can also lead to AFib due to increased left atrial pressure and size.
  • Patients are usually asymptomatic until the mitral valve area decreases to approximately 1.5 cm2 (normal valve area is 4 to 5 cm2).

Clinical Features of Mitral stenosis

  • Symptoms
    • Exertional dyspnea, orthopnea, PND
    • Palpitations, chest pain
    • Hemoptysis—as the elevated LA pressure ruptures anastomoses of small bronchial veins
    • Thromboembolism—often associated with AFib
    • If RV failure occurs, ascites and edema may develop
  • Signs
    • Mitral stenosis murmur. The opening snap is followed by a low-pitched diastolic rumble and presystolic accentuation. This murmur increases in length as the disease worsens. Heard best with bell of stethoscope in left lateral decubitus position. S2 is followed by an opening snap. The distance between S2 and the opening snap can give an indication as to the severity of the stenosis. The closer the opening snap follows S2, the worse is the stenosis.
    • Mitral stenosis murmur is followed by a loud S1. A loud S1 may be the most prominent physical finding.
    • With long-standing disease, we will find signs of RVF (e.g., right ventricular heave, JVD, hepatomegaly, ascites) and/or pulmonary HTN (loud P2).
    • All signs and symptoms will increase with exercise and during pregnancy.
  • Complications of MS:
    • Hemoptysis
    • AF
    • Pulmonary edema
    • IE
    • Chest pain

Features of Mitral stenosis murmur

Mitral Stenosis murmur
Mitral stenosis Murmur

Read about Aortic Stenosis Murmur

Diagnosis

  1. Echocardiogram—the most important test in confirming mitral stenosis. Findings include
    • Left atrial enlargement
    • Thick, calcified mitral valve
    • Narrow, “fish mouth”–shaped orifice
    • Signs of RVF, if advanced disease
      TTE is used to assess disease severity of mitral stenosis by measuring valve area and transvalvular gradient. TEE provides better visualization for the presence of left atrial appendage thrombus.
  2. CXR: Left atrial enlargement (early) Chest x-ray shows an enlarged pulmonary artery, left atrium, right ventricle, and right atrium.
  3. ECG shows RV hypertrophy and a notched P-wave duration >0.12 s in lead II (P mitrale).

Treatment

  1. Medical
    • No therapy is required in asymptomatic patients.
    • Diuretics—for pulmonary congestion and edema.
    • β-Blockers—to decrease heart rate (increase diastolic time to improve LV filling and LA emptying) and cardiac output.
    • If AFib develops at any time, treat accordingly
  2. Surgical (for severe disease)
    • PTMC
    • Mitral Valve surgery

Indication of PTMC in Mitral stenosis

Percutaneous balloon mitral commissurotomy is indicated for symptomatic patients (NYHA functional class II, III, or IV) and for asymptomatic patients when the valve area is <1.0 cm2. Valvular characteristics that favor a successful percutaneous commissurotomy include the presence of pliable leaflets, minimal commissural fusion, and minimal valvular or subvalvular calcification. Concurrent MR and left atrial thrombus are contraindications to valvulotomy.

Indication of Mitral valve surgery

Mitral valve surgery (repair if possible) is indicated in patients with symptomatic (NYHA functional class III-IV) mitral stenosis when balloon valvotomy is unavailable or contraindicated or the valve morphology is unfavorable.

References
1. https://www.bmj.com/content/335/7628/1042
2. https://www.ahajournals.org/doi/10.1161/CIRCULATIONAHA.104.532498

Leave a Reply

Your email address will not be published. Required fields are marked *