• Myocarditis—Adult

    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
    Copyright © Nucleus Medical Media, 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 or irregular 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

    Canadian Cardiovascular Society http://www.ccs.ca/home/index%5Fe.aspx

    Health Canada http://www.hc-sc.gc.ca/index-eng.php

    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.

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