What is myocarditis?
Myocarditis is an inflammation of the muscular walls of the
heart. The inflammation damages the individual heart muscle
cells. When too many heart muscle cells are damaged, the
heart can't pump effectively. The process may be rapid and
may result in death. More commonly, the heart begins to
heal itself. Heart muscle heals by changing dead cells to
scar tissue. Scar tissue does not contract and can't help
the heart to pump. If enough scar tissue forms, heart
failure may result.
How does it occur?
Many things can inflame the heart. Causes of myocarditis
include:
- infection, especially viral infection (the most common
cause)
- reactions to some drugs, such as doxorubicin and
zidovudine (AZT)
- exposure to some chemicals, such as lead, arsenic, and
carbon monoxide
- parasites in some parts of Central and South America
- autoimmune diseases (an over-reaction of the body's
immune system), such as lupus and rheumatoid arthritis.
What starts the inflammation is not always known. When the
cause of myocarditis is not known it is called idiopathic
myocarditis.
What are the symptoms?
Sometimes there are no symptoms. When symptoms occur, they
are the symptoms of heart failure, such as:
- running out of energy easily
- shortness of breath or trouble breathing, at first during
exercise and later with any activity or even when you are
resting
- waking up at night with trouble breathing or having a
hard time lying flat in bed because of shortness of
breath
- swollen ankles and feet and weight gain due to too much
fluid in the body.
How is it diagnosed?
Your healthcare provider will ask about your symptoms and
examine you. He or she will listen to your heart with a
stethoscope.
The first test is usually an echocardiogram (an ultrasound
scan of the heart).
Myocarditis can best be diagnosed by examining a small piece
of heart muscle under a microscope. This test is called a
biopsy. You will be given a local anesthetic so that you
will not feel any pain during the procedure. Samples of the
heart muscle are taken with a bioptome. A bioptome is a
thin, flexible tube (catheter) with small cutting jaws at
its tip. The bioptome is inserted through a vein in your
neck and then moved through the vein into your heart. The
cutting jaws remove very small pieces of muscle from inside
the heart. Results will be available within 48 hours.
Once myocarditis is diagnosed, you may have blood tests to
see if infection is the cause.
How is it treated?
The goals of treatment are to help the heart pump as it
heals itself and to limit the amount of damage as much as
possible. Drugs, and sometimes a device called an
intraaortic balloon pump, are used. Complications of
myocarditis, such as heart failure, can be treated if they
occur.
How long do the effects last?
About one third of people who have had myocarditis return to
normal after several weeks to several months. The rest have
permanent damage to the heart muscle. The damage can range
from slight to severe. There are effective treatments for
people whose hearts do not return to normal.
Written by Donald L. Warkentin, MD.
This content is reviewed periodically and is subject to
change as new health information becomes available. The
information is intended to inform and educate and is not a
replacement for medical evaluation, advice, diagnosis or
treatment by a healthcare professional.
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