Myocarditis

Definition

Myocarditis is an inflammation of the heart’s muscular wall, the myocardium. Although rare, it can be devastating. Myocarditis can occur with no symptoms and remain undiagnosed.

Healthy Myocardium

normal heart section

© 2008 Nucleus Medical Art, Inc.

Causes

Many cases of myocarditis have no identifiable cause. This is called idiopathic myocarditis. When a cause is identified, it falls into one of three categories: infectious, toxic, or immune-mediated.

Infectious

Toxic

  • Drugs, including chemotherapeutic drugs , lithium , or cocaine .
  • Heavy metals, including copper, iron, or lead.
  • Toxic substances, including arsenic, carbon monoxide, or other inhalants.
  • Physical agents, including electric shock or radiation.

Immune-mediated

  • Allergic reactions to penicillin or streptomycin.
  • Alloantigens, including heart transplant rejection.
  • Autoantigens, including Chagas’ disease, scleroderma , or lupus .

Risk Factors

A risk factor is something that increases your chance of getting a disease or condition.

There are no known risk factors for developing myocarditis.

Symptoms

The symptoms of myocarditis vary from person-to-person depending on the cause and the severity. Symptoms may appear slowly or come on suddenly.

If you have any of these symptoms you should contact your doctor right away.

  • Flu-like complaints, including fever, fatigue, muscle pain, vomiting, diarrhea , and weakness
  • Rapid heart rate
  • Chest pain
  • Shortness of breath and respiratory distress
  • Loss of consciousness
  • Sudden, unexpected death

Sudden, intense myocarditis can lead to congestive heart failure .

Some people have no symptoms (asymptomatic).

Diagnosis

The diagnosis of myocarditis is often difficult. There is no specific test for it. Many other causes of heart problems must be ruled out. To do this, your doctor will ask about your symptoms and medical history, and perform a physical exam.

Tests may include the following:

  • Electrocardiogram (ECG)—a test that records the heart’s activity by measuring electrical currents through the heart muscle.
  • Chest x-ray—a test that uses radiation to take pictures of structures inside the body.
  • Cardiac enzyme blood test—in some cases certain enzymes are elevated.
  • Echocardiogram—a test that uses high-frequency sound waves (ultrasound) to examine the size, shape, and motion of the heart.
  • Biopsy—removal of a sample of heart tissue to test for infection.
  • Cardiovascular magnetic resonance—the use of magnetic waves to take pictures of structures inside the body.

Treatment

The universally recommended therapy for myocarditis is bedrest, no physical activity, and supplemental oxygen. Corticosteroids may be given to help inflammation. You will most likely be admitted to a hospital.

Specific treatment is directed at the underlying cause if possible. For instance:

  • If the cause is a bacterial infection, antibiotics are prescribed.
  • If it is viral, antiviral agents will be prescribed.
  • Immunosuppressive therapy may be used if myocarditis is due to an autoimmune disorder such as lupus or scleroderma.

If heart failure symptoms are present, medications are given to support the function of the heart. These include diuretics, ACE-inhibitors, beta-blockers, and antiarrhythmic agents.

Additionally, a defibrillator, which helps maintain the normal rhythm of the heart, may be implanted into your chest. Severe cases may require a cardiac transplant.

Prevention

Myocarditis is hard to prevent. To help reduce your chances of getting myocarditis, reduce your exposure to identified causes. Some examples include:

  • Practice good hygiene to avoid the spread of infection. For example, wash your hands regularly.
  • Always use latex condoms during sexual activity.
  • Have sex with only one partner, who has sex only with you.
  • Do not use illegal drugs.

RESOURCES:

American Heart Association
http://www.americanheart.org

National Heart, Lung, and Blood Institute
http://www.nhlbi.nih.gov

CANADIAN RESOURCES:

BC Health Guide
http://www.bchealthguide.org/kbase/nord/nord1151.htm

Canadian Cardiovascular Society
http://www.ccs.ca/home/index_e.aspx

References:

Drory, Y, Turetz, Y, Hiss, Y, et al. Sudden unexpected death in persons less than 40 years of age. Am J Cardiol. 1991;68:1388.

Felker, GM, Thompson, R, Hare, J, et al. Underlying causes and long-term survival in patients with initially unexplained cardiomyopathy. N Engl J Med. 2000;342:1077.

Brady WJ, Ferguson JD, Ullman EA, Perron AD. Myocarditis: emergency department recognition and management. Emergency Medicine Clinics of North America . 2004;22(4):865-885.

Braunwald E, Zipes DP, Libby P, eds. Heart Disease: A Textbook of Cardiovascular Disease . 6th ed. Philadelphia, PA: WB Saunders Company; 2001.

Cohen J, et al. eds. Infectious Diseases . 2nd ed. Edinburgh, Scotland: Elsevier; 2004.

Feldman AM, McNamara D. Myocarditis. N Engl J Med . 2000;343(19):1388-1398.

Mandell GL, Bennett JE, Dolin R. Principles and Practice of Infectious Diseases . 6th ed. Philadelphia, Pa: Churchill Livingstone; 2005.

Marx JA, ed. Rosen’s Emergency Medicine: Concepts and Clinical Practice . 5th ed. St. Louis, MO: Mosby, Inc. 2002.

Myocardim and myocarditis. American Heart Association website. Available at: http://www.americanheart.org/presenter.jhtml?identifier=4729 . Accessed August 4, 2005.



Last reviewed March 2008 by Michael J. Fucci, DO

Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.

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