Myocarditis is inflammation of the heart muscle.
The condition is called pediatric myocarditis when it occurs in children.
Inflammation - heart muscle
Myocarditis is an uncommon disorder. Most of the time, it is caused by a viral, bacterial, or fungal infection that reaches the heart.
When you have an infection, your immune system produces special cells to fight off disease. If the infection affects your heart, the disease-fighting cells enter the heart. However, the chemicals produced by an immune response can damage the heart muscle. As a result, the heart can become thick, swollen, and weak. This leads to symptoms of heart failure.
Other causes of myocarditis may include:
- Allergic reactions to certain medicines or toxins (alcohol, cocaine, certain chemotherapy drugs, heavy metals, and catecholamines)
- Being around certain chemicals
- Certain diseases that cause inflammation throughout the body (rheumatoid arthritis, sarcoidosis)
There may be no symptoms. Symptoms may be similar to the flu. If symptoms occur, they may include:
- Abnormal heartbeat
- Chest pain that may resemble a heart attack
- Fever and other signs of infection including headache, muscle aches, sore throat, diarrhea, or rashes
- Joint pain or swelling
- Leg swelling
- Shortness of breath
Other symptoms that may occur with this disease:
Exams and Tests
A physical exam may show no abnormalities, or may reveal the following:
- Abnormal heartbeat or heart sounds (murmurs, extra heart sounds)
- Fluid in the lungs
- Rapid heartbeat (tachycardia)
- Swelling (edema) in the legs or abdomen
Tests used to diagnosis myocarditis include:
- Blood cultures for infection
- Blood tests for antibodies against the heart muscle and the body itself
- Chest x-ray
- Electrocardiogram (ECG)
- Heart muscle biopsy (endomyocardial biopsy)
- Red blood cell count
- Ultrasound of the heart (echocardiogram)
- White blood cell count
Treatment is aimed at the cause of the problem, and may involve:
- Anti-inflammatory medicines to reduce swelling
- Diuretics to remove excess water from the body
- Low-salt diet
- Reduced activity
If the heart muscle is weak, your health care provider will prescribe medicines to treat heart failure. Abnormal heart rhythms may require the use of other medicines. You may also need a device such as a pacemaker, or an implantable cardioverter-defibrillator to correct an irregular heartbeat. If a blood clot is in the heart chamber, you will also receive blood thinning medicine.
Rarely, a heart transplant may be needed if the heart muscle has become very weak or you have other health problems.
Your outcome can vary, depending on the cause of the problem and your overall health. Some people may recover completely. Others may have lasting heart failure.
When to Contact a Medical Professional
Call your health care provider if you have symptoms of myocarditis, especially after a recent infection.
Seek medical help right away if:
- Your symptoms are severe
- You have been myocarditis, and you have increased chest pain, swelling, or breathing problems
Treat conditions that cause myocarditis promptly to reduce the risk.
Liu P, Baughman KL. Myocarditis. In: Bonow RO, Mann DL, Zipes DP, Libby P, eds. Braunwald's Heart Disease: A Textbook of Cardiovascular Medicine. 9th ed. Philadelphia, PA: Saunders Elsevier; 2011:chap 70.
McKenna W. Diseases of the myocardium and endocardium. In: Goldman L, Schafer AI, eds. Goldman's Cecil Medicine. 24th ed. Philadelphia, PA: Saunders Elsevier; 2011:chap 60.
Reviewed By: Michael A. Chen, MD, PhD, Associate Professor of Medicine, Division of Cardiology, Harborview Medical Center, University of Washington Medical School, Seattle, Washington. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.