Mitral Regurgitation

Aka: Mitral Regurgitation, Mitral Valve Papillary Muscle Rupture

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II. Precautions

  1. Evaluation and management here focuses on chronic Mitral Regurgitation
  2. Acute Mitral Regurgitation with papillary Muscle rupture is also described, but requires emergent management

III. Pathophysiology

  1. Dysfunction of any of the mitral valve structure may result in Mitral Regurgitation
    1. Mitral valve leaflets
    2. Chordae Tendinae
    3. Papillary Muscles
    4. Mitral annulus
  2. Chronic Early or compensated Mitral Regurgitation
    1. Volume overload
    2. Left Ventricular Hypertrophy
    3. Left atrial enlargement
  3. Chronic Late or decompensated Mitral Regurgitation
    1. Left Ventricular Failure
    2. Decreased ejection fraction
    3. Pulmonary congestion
  4. Acute Mitral Regurgitation due to papillary Muscle rupture
    1. Typically affects posteromedial papillary Muscle (most tenuous blood supply)

IV. Causes: Acute Mitral Regurgitation (due to papillary Muscle rupture)

  1. Common causes of papillary Muscle rupture
    1. Acute Myocardial Infarction
      1. Associated with 50% acute mortality rate
  2. Rare causes of papillary Muscle rupture
    1. Infective Endocarditis
    2. Mitral Valve Prolapse

V. Causes: Chronic Mitral Regurgitation

  1. Rheumatic Heart Disease (50%)
    1. May be associated with Mitral Stenosis
  2. Mitral Valve Prolapse
    1. May be associated with Atrial Septal Defect (ASD)
    2. May be associated with Polycystic Kidney Disease
  3. Ischemic Heart Disease and papillary Muscle dysfunction
  4. Left Ventricular dilatation
  5. Mitral annular calcification
  6. Hypertrophic Cardiomyopathy
  7. Infective Endocarditis
  8. Congenital Mitral Regurgitation

VI. Symptoms

  1. Dyspnea
  2. Fatigue
  3. Weakness
  4. Cough

VII. Signs: General

  1. Holosystolic Murmur at Apex
    1. Harsh, medium pitched pansystolic murmur (without respiratory variation)
    2. Murmur obliterates M1
    3. Radiation
      1. Axilla
      2. Upper sternal borders
      3. Subscapular region
    4. Modifiers
      1. Murmur intensity decreases with squatting
      2. Murmur intensity increases with standing
  2. Other heart sounds
    1. Soft or diminished First Heart Sound (S1)
    2. P2 heart sound augmented
    3. S2 Heart Sound with wide split
    4. S3 Gallop rhythm (indicative of severe disease)
  3. Other findings
    1. Accentuated, hyperdynamic and displaced precordial Apical Thrust
    2. Systolic thrill
    3. Sharp carotid upstroke (contrast with the delayed and decreased pulsation of Aortic Stenosis)

VIII. Signs: Acute Mitral Regurgitation (in contrast to chronic MR)

  1. Pulsus Alternans (high volume in chronic MR)
  2. Jugular Venous Pressure markedly elevated (mild in chronic MR)
  3. Pulmonary Hypertension severe
  4. S3 gallup and S4 gallup present (S4 is always absent in chronic MR)
  5. Late Systolic Murmur (holosystolic in chronic MR)

IX. Signs: Rheumatic Heart Disease related Mitral Regurgitation (in contrast to MR with prolapse)

  1. Posterior valve leaflets affected
  2. Soft S1 (contrast with loud with midsystolic click in Mitral prolapse/regurgitation)
  3. Holosystolic murmur increases with with squatting and isometric handgrip
    1. Contrast with midsystolic murmur decreased with squatting/handgrip in prolapse/MR

X. Diagnostics: Electrocardiogram

  1. Left Ventricular Hypertrophy
  2. Left Axis Deviation
  3. Atrial Fibrillation may be present in chronic Mitral Regurgitation

XI. Imaging

  1. Chest XRay
    1. Enlarged left atrium
    2. Dilated left ventricle
  2. Echocardiogram
    1. Most important study in the evaluation of Mitral Regurgitation
    2. Test Sensitivity: 65-85%
    3. Associated Findings
      1. Enlarged left atrium
      2. Hyperdynamic left ventricle
      3. Doppler assesses severity

XII. Monitoring

  1. Annual or semi-annual Echocardiogram
    1. Assess ejection fraction
    2. Assess end-systolic dimension

XIII. Management

  1. SBE Prophylaxis is no longer recommended
  2. Anticoagulation in Atrial Fibrillation
  3. Treat Congestive Heart Failure
    1. Diuretics
    2. Digoxin
    3. Afterload reduction
      1. ACE Inhibitor
      2. Hydralazine
      3. Nitroprusside IV
      4. Milrinone (also inotropic)
  4. Surgery: Mitral Valve repair or replacement
    1. Repair before Heart Failure develops
      1. Keep ejection fraction >60%
      2. Keep end-systolic dimension <45 mm
    2. Indications
      1. Cardiopulmonary Symptoms
      2. Left Ventricular function impaired

XIV. Complications

  1. Congestive Heart Failure
  2. Atrial Fibrillation (chronic Mitral Regurgitation)
  3. Pulmonary Hypertension
  4. Systolic anterior motion of the mitral valve (SAM)
    1. May complicate Mitral valve regurgitation or Mitral Valve Prolapse
    2. Mitral valve lodges in the left ventricular outflow tract resulting in mechanical obstruction
    3. Risk for Left Ventricular Outflow Obstruction (LVOTO)

XV. References

  1. Baloor (2018) Exam Preparatory Manual for Undergraduates Medicine, Jaypee Brothers, India
  2. Kondos (1998) CMEA Medicine Review Lecture, San Diego
  3. Assi (1998) Postgrad Med 104(6):99-110 [PubMed]
  4. Bonow (1998) Circulation 98:1949-84 [PubMed]
  5. Carabello (1997) N Engl J Med 337(1):32-41 [PubMed]
  6. Shipton (2001) Am Fam Physician 63(11):2201-8 [PubMed]

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