It may also be caused by bacterial infections such as Lyme disease.
Other causes of pediatric myocarditis include:
Allergic reactions to certain medicines
Exposure to chemicals in the environment
Infections due to fungus or parasites
Some diseases (autoimmune disorders) that cause inflammation throughout the body
The heart muscle may be directly damaged by the virus or the bacteria that infect it. The body's immune response can also damage the heart muscle (called the myocardium) in the process of fighting the infection. This can lead to symptoms of heart failure.
Symptoms may be mild at first and hard to detect. Sometimes in newborns and infants, symptoms may appear suddenly.
Heart biopsy (the most accurate way to confirm the diagnosis, but not always needed)
Special tests to check for the presence of viruses in the blood (viral PCR)
There is no cure for myocarditis. The heart muscle inflammation will often go away on its own.
The goal of treatment is to support heart function until the inflammation goes away. Many children with this condition are admitted to a hospital. Activity often needs to be limited while the heart is inflamed because it can strain the heart.
Treatment may include:
Antibiotics to fight bacterial infection
Anti-inflammatory medicines called steroids to control inflammation
Intravenous immunoglobulin (IVIG), a medicine made of substances (called antibodies) that the body produces to fight infection, to control the inflammatory process
Mechanical support using a machine to help the heart function (in extreme cases)
Medicines to treat symptoms of heart failure
Medicines to treat abnormal heart rhythms
Recovery from myocarditis depends on the cause of the problem and the child's overall health. Most children recover completely with proper treatment. However, some may have permanent heart disease.
Newborns have the highest risk for serious disease and complications (including death) due to myocarditis. In rare cases, severe damage to the heart muscle requires a heart transplant.
Complications may include:
Enlargement of the heart that leads to reduced heart function (dilated cardiomyopathy)
Heart rhythm problems
When to Contact a Medical Professional
Call your child's pediatrician if signs or symptoms of this condition occur.
There is no known prevention. However, prompt testing and treatment may reduce the disease risk.
Knowlton KU, Anderson JL, Savoia MC, Oxman MN. Myocarditis and pericarditis. In: Bennett JE, Dolin R, Blaser MJ, eds. Mandell, Douglas, and Bennett's Principles and Practice of Infectious Diseases. 9th ed. Philadelphia, PA: Elsevier; 2020:chap 84.
McNamara DM. Heart failure as a consequence of viral and nonviral myocarditis. In: Felker GM, Mann DL, eds. Heart Failure: A Companion to Braunwald's Heart Disease. 4th ed. Philadelphia, PA: Elsevier; 2020:chap 28.
Parent JJ, Ware SM. Diseases of the myocardium. In: Kliegman RM, St. Geme JW, Blum NJ, Shah SS, Tasker RC, Wilson KM, eds. Nelson Textbook of Pediatrics. 21st ed. Philadelphia, PA: Elsevier; 2020:chap 466.
Neil K. Kaneshiro, MD, MHA, Clinical Professor of Pediatrics, University of Washington School of Medicine, Seattle, WA. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.