What is myocarditis?
Myocarditis is an inflammation of the muscular walls of the
heart. Inflammation causes damage to the individual heart
muscle cells.
How does it occur?
What starts the inflammation is not always known. When the
cause of myocarditis is not known it is called idiopathic.
Causes of myocarditis include infection and allergic
reactions to drugs. The most common cause of myocarditis is
a viral infection. Myocarditis may occur as a side effect
of cancer treatment with radiation and certain drugs. It
may also be caused by exposure to certain chemicals.
Although rare, myocarditis can also be caused by the germ
that causes Lyme disease. In some parts of the world, a
parasite often causes it. Some of the damage may occur from
an over-reaction of the body's immune system.
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 is it diagnosed?
The first test you will have is usually an echocardiogram.
Myocarditis can best be diagnosed by examining a small piece
of heart muscle under a microscope. Samples of the heart
muscle are taken with a bioptome. A bioptome is a thin,
flexible tube with small cutting jaws at its tip. The
bioptome is inserted through a vein in your neck and
positioned in the heart. Once the bioptome is in position,
the cutting jaws withdraw very small heart muscle samples
for analysis. You will be given a shot to numb the area
where the bioptome is inserted, but you will remain awake.
You may experience minor discomfort but the procedure is
usually painless. Results will be available within 48
hours.
Once myocarditis is diagnosed, blood tests might be done to
try to find out if infection is the cause, and which germ
caused the infection.
How is it treated?
The goals of treatment are to support the function of the
heart as it heals itself and to reduce the amount of damage
as much as possible. Drugs, and sometimes a device called an
intra-aortic balloon pump, are used. Complications of
myocarditis, like heart failure, can be treated if they
occur.
How long do the effects last?
About one-third of people affected will return to normal
over several weeks to several months. The rest will have
permanent damage to the heart muscle. The amount of damage
varies from slight to more severe. The amount of permanent
damage is hard to predict. There are effective treatments
for patients whose hearts do not return to normal.


Disclaimer: This content is reviewed periodically and is subject to
change as new health information becomes available. The
information provided is intended to be informative and educational and is not a
replacement for professional medical evaluation, advice, diagnosis or
treatment by a healthcare professional.
HIA File CRD3641F.HTM Release 9.0/2006. Copyright © 2006 McKesson Corporation and/or one of its subdiaries. All Rights Reserved.
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