What is this condition?

This disorder involves focal or diffuse inflammation of the cardiac muscle (myocardium). It may be acute or chronic and can occur at any age. Frequently, this disease fails to cause specific cardiovascular symptoms or electrocardiogram abnormalities, and recovery is usually spontaneous, without residual defects. Occasionally, it’s complicated by heart failure.

What causes it?

Inflammation of the heart muscle is caused by:

  • viral injections, such as coxsackievirus A and B strains and, possibly, polio, influenza, measles, German measles, adenoviruses, and echoviruses (most common causes in the United States)
  • bacterial injections, such as diphtheria, tuberculosis, typhoid fever, tetanus, and staphylococcal, pneumococcal, and gonococcal infections
  • hypersensitive immune reactions, such as acute rheumatic fever and postcardiotomy syndrome
  • radiation therapy from large doses of radiation to the chest in treating lung or breast cancer
  • chemical poisons, as in chronic alcoholism
  • parasitic injections, especially South American trypanosomlasis (Chagas’ disease) in infants and immunosuppressed adults, and toxoplasmosis
  • injections caused by parasitic worms, such as trichinosis.

What are its symptoms?

Inflammation of the heart muscle usually causes nonspecific symptoms (such as fatigue, shortness of breath, palpitations, and fever) that reflect the accompanying infection. Occasionally, it may cause mild, continuous pressure or soreness in the chest.

How is it diagnosed?

The person’s history commonly reveals recent febrile upper respiratory tract infection, viral pharyngitis, or tonsillitis. A physical exam detects irregular heart rhythms, abnormal heart sounds, and possibly a murmur.

An electrocardiogram typically shows abnormalities in heart rhythm. Stool and throat cultures may identifY bacteria.

How is Myocarditis Treated?

Myocarditis treatment includes antibiotics for bacterial infection, modified bed rest to decrease the heart’s workload, and careful management of complications.

Heart failure requires restricted physical activiry to minimize myocardial oxygen consumption, supplemental oxygen therapy, restricted salt intake, diuretics to decrease fluid retention, and Lanoxin to increase myocardial contractility. However, Lanoxin must be used cautiously because some people with inflammation of the heart muscle may be sensitive to even small doses.

Irregular heart rhythms require prompt but cautious administration of antiarrhythmic drugs, such as Cardioquin or Pronestyl.