Definition

Myocarditis is a rare inflammation of the heart’s muscle. Myocarditis can occur without symptoms and remain undiagnosed.

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Causes

In most children, the condition is often caused by a viral infection. Other potential causes include:

• Certain medications
• Autoimmune disorders
• Infections by bacteria, parasites, or fungus

Sometimes the cause cannot be found.

Risk Factors

There are no known risk factors for developing myocarditis.

Symptoms

Some children may have no symptoms. Those who do may have a variety symptoms that can appear slowly or come on suddenly. Children older than 2 years old may have fewer symptoms than babies.

Symptoms may include:

• Flu-like complaints, including fever, fatigue, muscle or joint pain, vomiting, diarrhea, and weakness
• Rapid or irregular heart rate
• Chest pain
• Trouble breathing
• Loss of consciousness
• Swelling of the face, feet, or legs
• Abdominal pain
• Decreased urine output

Diagnosis

You will be asked about your child’s symptoms and medical history. A physical exam will be done. There is no specific test for myocarditis. The diagnosis can usually be made based on the history, physical exam, and test results.

Your child's bodily fluids and tissues may be tested. This can be done with:

• Blood tests
• Biopsy

Images may be taken of your child's bodily structures. This can be done with:

• Chest x-ray
• Echocardiogram
• MRI scan 

The electrical activity of your child's heart may be measured. This can be done with an electrocardiogram (ECG).

Treatment

Your child will need bed rest. Physical activity should be avoided. Myocarditis may be relieved by treating the underlying cause if possible:

• Antibiotics may be given for a bacterial infection
• Antiviral agents may be given if a virus in involved
• Immunosuppressive or immunoglobulin therapy may be used if an autoimmune disorder is involved

Medication may also be given to support the heart function and remove extra fluid from the lungs or other body tissues.

Prevention

To help prevent viral or bacterial infections, practice good hygiene. For example, have your child wash his or her hands regularly.