Myocarditis

I40

DESCRIPTION

Myocarditis is an inflammatory disease of the cardiac muscle. The majority of paediatric myocarditis cases are caused by viral infection. Viral myocarditis should be suspected whenever a child presents with dysrhythmia, heart failure or cardiogenic shock following a viral illness. Myocarditis should be considered in children with unexplained shortness of breath.

DIAGNOSTIC CRITERIA

Clinical

  • Tachycardia.
  • Clinical signs of biventricular heart failure.
  • May present with cardiogenic shock.

Investigations

  • ECG changes are non-specific but ST elevation, T wave inversion, prolonged QTc, small complexes, dysrhythmias or extra-systole may be seen.
  • Chest X-ray:
    • pulmonary congestion,
    • cardiomegaly,
    • possible pleural effusion.
  • Elevated cardiac troponin T levels are markers of myocarditis but normal levels do not exclude the diagnosis.

GENERAL AND SUPPORTIVE MEASURES

  • Restrict fluid (75% of daily requirements) – not at expense of adequate caloric intake.
  • Ensure adequate nutrition, tube-feeding may be necessary.

MEDICINE TREATMENT OF VIRAL MYOCARDITIS

To prevent hypoxia:

  • Oxygen via face mask, nasal cannula or head box.

For pulmonary oedema:

  • Furosemide, IV, 1mg/kg, 8 hourly monitor urinary output
  • If response is inadequate, change to an IV infusion 0.1-1 mg/kg/hour.
  • Switch to oral furosemide as soon as patient condition allows.
    • Monitor clinically and biochemically for, and avoid, over diuresis.
    • Monitor for hypokalaemia and other electrolyte disturbances.

LoEIII [3]

If response still inadequate consider:

  • Hydrochlorothiazide, oral, 1mg/kg/dose, 12 hourly in consultation with a paediatric cardiologist.

LoEIII [11]
LoEIII [12]

REFERRAL

  • All children with suspected myocarditis should be managed in consultation with a paediatrician. Long term (at least 6 months) exercise avoidance, medicine treatment and follow up is needed.