Myocarditis

Causes

Causes of Myocarditis

Medical conditions which can cause myocarditis include:

Viruses

A common form of myocarditis often occurs after a viral infection of the nose and throat, and often goes away on its own. Coxsackievirus B is a common cause of myocarditis in the United States. Other viruses include adenovirus (common cold), Parvovirus B19, echovirus, influenza (flu), Epstein-Barr, rubella, varicella (chickenpox), mumps and hepatitis.

HIV

About 10 percent of people with HIV develop cardiomyopathy. This can be due to the HIV invading the heart muscle, the drugs used to treat HIV, or the patient's weakened immune system which makes the heart muscle more susceptible to attack.

Bacteria

Myocarditis can occur as a complication of endocarditis, an infection of the heart valves and the lining inside the heart's chambers caused by bacteria such as staphylococcus aureus, enterococci and Corynebacterium diphtheriae (the cause of diphtheria).

Chagas' disease

Caused by a protozoa, this disease is transmitted by insects. In the United States, myocarditis caused by Chagas' disease is common among travelers or immigrants from Central and South America.

Lyme diseases

An infection caused by the tick-borne bacterium Borrelia burgdorferi, Lyme disease causes myocarditis or other heart problems in about 10 percent of patients.

Giant cell myocarditis

This rare form of myocarditis gets its name from large, abnormal giant cells that are found when a piece of the affected heart muscle is examined under a microscope. It is most common among patients with thymoma (a growth of the thymus gland), lupus, or thyrotoxicosis (an overactive thyroid), but its true cause remains a mystery. The illness usually strikes young adults, and it can quickly lead to death from heart failure and/or cardiac arrhythmia.

Other agents

Myocarditis also can be caused by alcohol, radiation, chemicals (hydrocarbons and arsenic) and some medications.

Prevention of Myocarditis

Prompt treatment of diseases that can lead to myocarditis may reduce the risk of developing the condition. Many cases caused by infections can be avoided by practicing good hygiene, especially frequent hand washing.

Diphtheria myocarditis can be prevented by immunization, and HIV can be prevented by following safe sex practices and avoiding intravenous drug use. Myocarditis caused by insect-borne Chagas' disease can be prevented by the use of effective insecticides in Latin American countries where the illness is common. A new vaccine recently was approved to prevent Lyme disease.