Health Encyclopedia

Myocarditis

Definition

Myocarditis is inflammation of the heart muscle.

Alternative Names

Inflammation - heart muscle

Causes, incidence, and risk factors

Myocarditis is an uncommon disorder that is usually caused by viral, bacterial, or fungal infections that reach the heart.

Viral infections:

Coxsackie
Cytomegalovirus
Hepatitis C
Herpes
HIV
Parvovirus

Bacterial infections:

Chlamydia
Mycoplasma
Streptococcus
Treponema

Fungal infections:

Aspergillus
Candida
Coccidioides
Cryptococcus
Histoplasma
Schistosomiasis

When you have an infection, your immune system produces special cells that release chemicals 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 medications 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)

Symptoms

There may be no symptoms. If symptoms occur, they may include:

Abnormal heartbeat
Chest pain that may resemble a heart attack
Fatigue
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:

Fainting, often related to irregular heart rhythms
Low urine output

Signs and tests

A physical examination 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

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

Treatment is aimed at the cause of the problem, and may involve:

Antibiotics
Anti-inflammatory medicines to reduce swelling
Diuretics to remove excess water from the body
Low-salt diet
Reduced activity

If the heart muscle is very weak, your health care provider will prescribe medicines to treat heart failure. Abnormal heart rhythms may require the use of additional medications, a pacemaker, or an implantable cardioverter-defibrillator. If a blood clot is in the heart chamber, you will also receive blood thinning medicine.

Expectations (prognosis)

How well you do depends on the cause of the problem and your overall health. The outlook varies. Some people may recover completely. Others may have permanent heart failure.

Complications

Calling your health care provider

Call your health care provider if you have symptoms of myocarditis, especially after a recent infection.

Seek immediate medical help if you have severe symptoms or have been diagnosed with myocarditis and have increased:

Prevention

Promptly treating conditions that cause myocarditis may reduce the risk.

References

Liu PP, Schultheiss HP. Myocarditis. In: Libby P, Bonow RO, Mann DL, Zipes DP. Libby: Braunwald's Heart Disease: A Textbook of Cardiovascular Medicine. 8th ed. Philadelphia, Pa: Saunders Elsevier; 2007;chap 66.

Review Date:5/15/2008
Reviewed By:Alan Berger, MD, Assistant Professor, Divisions of Cardiology and Epidemiology, University of Minnesota, Minneapolis, MN. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.

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