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Myocarditis

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Myocarditis, Viral Myocarditis, Postinfectious Myocarditis, Dilated Cardiomyopathy Secondary to Viral Myocarditis, Viral Carditis

  • Epidemiology
  1. Ages
    1. Children: Age <2 years old
    2. Adolescents: Age 14 to 18 years old
    3. Adults: Ages 20 to 40 years old
  • Causes
  1. See Secondary Cardiomyopathy (includes Viral Myocarditis Causes)
  • Associated Conditions
  • Symptoms
  1. Presentations vary widely
    1. Most cases are mild and asymptomatic
    2. However, can be severe and life-threatening (especially in children)
      1. May be responsible for up to 20% of unexplained cardiac death in young adults
  2. Influenza-like illness presentation is common
    1. Fever (Viral Myocarditis)
    2. Fatigue
    3. Myalgias
    4. Arthralgias
    5. Malaise
  3. Chest symptoms
    1. Palpitations
    2. Chest Pain
    3. Sinus Tachycardia out of proportion to other findings (or other dysrhythmia)
    4. Dyspnea on exertion
  4. Symptoms related to secondary events and decompensation
    1. Myocardial Infarction
    2. Congestive Heart Failure
  5. Infant and young child presentation
    1. Poor feeding
    2. Lethargy
    3. Respiratory distress (Tachypnea, intercostal retractions, grunting)
    4. Gastrointestinal Symptoms (Nausea, Vomiting or Abdominal Pain)
  • Signs
  1. Pericardial Friction Rub
  2. Loud S3 Gallop
  3. Sinus Tachycardia (or other fast dysrhythmia)
    1. Out of proportion to other causes (e.g. beyond what would be expected with fever alone)
  4. Weak pulses
  • Labs
  1. Complete Blood Count
    1. Leukocytosis
  2. Troponin I increased
    1. Often normal, especially in children
  3. Brain Natriuretic Peptide (BNP, ntBNP) increased
  4. Thyroid Stimulating Hormone (TSH)
  5. Lactic Acid
  6. Venous Blood Gas (VBG)
  7. Serum Aspartate Aminotransferase
    1. Nonspecific increase is also seen with Kawasaki Disease
  8. Acute phase reactants
    1. Erythrocyte Sedimentation Rate (ESR) >60 mm/h
    2. C-Reactive Protein (CRP) increased
  1. Sinus Tachycardia
  2. Low-voltage QRS Complexes
  3. Diffuse EKG changes (all leads)
  4. Saddle-shaped ST segment elevation progresses to T Wave inversion
  5. EKG normalizes in 2 months
  6. Conduction abnormalities including complete Heart Block may occur
  • Imaging
  1. Chest XRay
    1. Cardiomegaly in 50% cases
    2. Pulmonary vascular congestion
    3. Pleural Effusions
  2. Echocardiogram
    1. Dilated Cardiomyopathy
    2. Left Ventricular Dilation
    3. Decreased ejection fraction
  3. Cardiac MRI
    1. Most accurate non-invasive imaging modality to diagnose Myocarditis
    2. Assess LV Ejection fraction, wall thickness, ventricle size, tissue injury
  4. Endomyocardial Biopsy Indications
    1. Fulminant myocardititis
    2. Acute Dilated Cardiomyopathy with VT or complete Heart Block refractory to standard management
  • Management
  1. Management is typically symptomatic
  2. Specific management may be based on underlying cause
    1. Lyme Disease
    2. Mycobacterium tuberculosis
    3. Trypanosoma cruzi
  3. Disposition is based on severity of clinical presentation
    1. Initial inpatient management is waranted in severe cases
    2. Most acute Myocarditis in young children are admitted, often to intensive care unit
  4. Young children may present in severe CHF, and require intensive management
    1. Endotracheal Intubation
    2. Inotropic support (Dopamine, Dobutamine, Milrinone)
    3. Consider Diuretics (Furosemide) if hypertensive and Fluid Overload
    4. Afterload reduction
    5. Dysrhythmia management (e.g. Amiodarone, Lidocaine)
    6. Transfer to pediatric intensive care with ECMO capability
  5. Various agents have been used historically, especially for Viral Myocarditis (e.g. coxsachievirus)
    1. IV Ig (effective in Kawasaki's Disease, but not in Viral Myocarditis)
      1. Robinson (2015) Cochrane Database Syst Rev (5): CD004370 [PubMed]
    2. Immunosuppresants (Corticosteroids, Cyclosporine) have not been effective in Viral Myocarditis
      1. Chen (2013) Cochrane Database Syst Rev (1):CD004471 [PubMed]
  • References
  1. Claudius, Behar, Salway and Kearl in Herbert (2018) EM:Rap 18(5): 1-3
  2. Sharrief in Majoewsky (2012) EM:Rap 12(5): 8
  3. Klauer (2013) Congestive Heart Failure and Myocarditis, EM Bootcamp, CEME
  4. Pacheco and Rawani-Patel (2019) Crit Dec Emerg Med 33(5): 3-11