Myocarditis
Description Diagnostic criteria General and supportive measures Medicine treatment of viral myocarditis Referral ICD-10 code: 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 arrhythmia, heart failure or cardiogenic sho
Description
Diagnostic criteria
General and supportive measures
Medicine treatment of viral myocarditis
Referral
ICD-10 code: 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 arrhythmia, 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, CPAP or high flow.
For pulmonary oedema:
- Furosemide, IV, 1 mg/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.
If response still inadequate consider:
- Spironolactone, oral, 1–3 mg/kg/dose once daily in consultation with a paediatric cardiologist. May be divided 12 hourly.
- Inotropic support may be needed, see: Heart failure, acute with pulmonary oedema.
- IV immunoglobulins are not recommended12.
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.
Standard Treatment Guidelines And Essential Medicines List For South Africa, Hospital Level, Paediatrics, 2023 Edition
Chapter 4: Cardiovascular System , 4.5 Myocarditis