Definition

Myocarditis is an inflammation of the heart’s wall. It is rare and can be very serious.

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Causes

The cause of myocarditis is not always known. Causes that are known are:

• Infectious—from bacteria, protozoa, viruses, or fungi
• Toxic—from medicines, or exposure to heavy metals, toxins, shock, or radiation
• Problems of the immune system—allergic reactions, heart transplant rejection, or autoimmune disease

Risk Factors

There are no known risk factors.

Symptoms

Myocarditis may not cause symptoms. When symptoms happen, they may be:

• Flu-like symptoms—such as fever, tiredness, muscle pain, vomiting, loose stools (poop), and weakness
• Fast or uneven heartbeats
• Chest pain
• Leg swelling
• Problems breathing
• Loss of consciousness
• Sudden, unexpected death

Myocarditis can lead to heart failure.

Diagnosis

It can be hard to diagnosis myocarditis. There is no specific test for it. Other causes of heart problems must be ruled out first.

The doctor will ask about symptoms and past health. A physical exam will be done. Tests may include:

• Blood tests—to look for signs of heart damage or infection
• ECG—to see the heart’s electrical activity
• Biopsy—a sample of heart tissue is removed for testing (rare)

Images of the heart may be taken with:

• Echocardiogram
• MRI scan

Treatment

The first line of treatment is support care. The goal is to manage symptoms and slow or prevent more damage. Care will often require a hospital stay.

When possible, the cause will be treated. For example:

• Antibiotics—for bacterial infections
• Antiviral medicine—for viral infections
• Medicines to adjust the immune system—for autoimmune disorders (such as systemic lupus erythematosus or scleroderma)

If heart failure is present, it may be treated with:

• Medicines to support the heart
• An implanted device to help pump blood—if other treatments do not help
• A heart transplant—for severe heart damage

Prevention

It is not possible to prevent all myocarditis. To lower the risk of infection that could lead to myocarditis:

• Wash hands often.
• Use latex condoms during sex.
• Do not use drugs for non-medical reasons.

For those with HIV, special antiviral therapy may help lower the risk of myocarditis.