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What Is Cardiomyopathy?
Cardiomyopathy (KAR-de-o-mi-OP-a-the) refers to diseases
of the heart muscle. These diseases have a variety of causes,
symptoms, and treatments. In cardiomyopathy, the heart muscle
becomes enlarged or abnormally thick or rigid. In rare cases,
the muscle tissue in the heart is replaced with scar tissue.
As cardiomyopathy progresses, the heart becomes weaker and
less able to pump blood through the body. This can lead to
heart failure, arrhythmias (ah-RITH-me-ahs;
abnormal heart rhythms), fluid buildup in the lungs or legs,
and, more rarely, endocarditis (a
bacterial infection of the lining of the heart). The weakening
of the heart also can lead to other severe complications.
The four main types of cardiomyopathy are:
- Dilated cardiomyopathy
- Hypertrophic (hi-per-TROF-ik) cardiomyopathy
- Restrictive cardiomyopathy
- Arrhythmogenic (a-rith-mo-JEN-ik) right ventricular dysplasia
(ARVD)
Cardiomyopathy can have a specific cause, such as damage
to the heart from a heart
attack, high
blood pressure, or a viral infection. Some types of cardiomyopathy
are caused by a gene mutation and run in families. In many
cases, the cause is unknown.
Cardiomyopathy can affect people of all ages, from babies
to older adults. However, certain age groups are more likely
to have certain types of cardiomyopathy. Treatment may involve
medicines, surgery, nonsurgical procedures, and lifestyle
changes.
Outlook
Some people live long, healthy lives in spite of having
cardiomyopathy. Some people don't even realize that they
have the disease because they have no symptoms. In other
people, the disease develops rapidly, symptoms are severe,
and serious complications develop. Current treatments can
reduce symptoms and complications of cardiomyopathy.
Types of Cardiomyopathy
Dilated Cardiomyopathy
Dilated cardiomyopathy is the most common form of cardiomyopathy.
It generally occurs in adults aged 20 to 60 years. Men are
more likely than women to develop dilated cardiomyopathy.
Dilated cardiomyopathy affects the heart's ventricles (VEN-trih-kuls)
and atria. The ventricles are the two lower chambers of the
heart, and the atria are the two upper chambers. Dilated
cardiomyopathy usually starts in the left ventricle, where
the heart muscle begins to dilate or stretch and become thinner.
This leads to enlargement of the inside of the ventricle.
The problem often spreads to the right ventricle and then
to the atria as the disease gets worse.
When the chambers dilate, the heart can't pump blood very
well. The heart tries to cope by dilating the chambers even
more. Over time, the heart becomes weaker and heart
failure can occur. Symptoms of heart failure include
feeling tired, swelling of the legs and feet, and shortness
of breath. Dilated cardiomyopathy also can lead to heart
valve problems, arrhythmias,
and blood clots in the heart. Having advanced dilated cardiomyopathy
is a common reason for needing a heart transplant.
Up to one-half of all cases of dilated cardiomyopathy may
be hereditary (passed down in the genes from parent to child).
These cases are called familial dilated cardiomyopathy. Dilated
cardiomyopathy also can be a complication of many conditions,
including coronary
artery disease and high
blood pressure. It also can be caused by viral infections,
excessive use of alcohol, and exposure to certain drugs (including
cocaine, amphetamines, and some drugs used in cancer treatments).
In some cases, no cause can be found.
Hypertrophic Cardiomyopathy
Hypertrophic cardiomyopathy occurs when the heart muscle
thickens abnormally. The thickening generally happens in
the left ventricle, the heart's main pumping chamber. This
type of cardiomyopathy can affect people of any age.
Hypertrophic cardiomyopathy can be obstructive or nonobstructive.
In the obstructive type, the septum (the wall that divides
the left and right sides of the heart) thickens and bulges
into the left ventricle. This bulge blocks the flow of blood
out of the ventricle. The ventricle must work much harder
to pump blood past the blockage and out to the body. Symptoms
can include chest pain, dizziness, shortness of breath, or
fainting.
Obstructive hypertrophic cardiomyopathy also can affect
the heart's mitral (MI-trul) valve, causing blood to leak
backward through the valve.
In nonobstructive hypertrophic cardiomyopathy, the thickened
heart muscle does not block the flow of blood out of the
ventricle. The entire ventricle may become thicker (symmetric
ventricular hypotrophy) or it may happen only at the bottom
of the heart (apical hypertrophy). The right ventricle also
may be affected.
In both kinds of hypertrophic cardiomyopathy, the thickened
muscle makes the inside of the left ventricle smaller so
that it holds less blood. The walls of the ventricles also
may become stiff. As a result, they are less able to relax
and fill with blood. This causes increased pressure in the
ventricles and the blood vessels of the lungs. Changes also
occur to the cells in the damaged heart muscle. This may
interfere with the heart's electrical signals, leading to
arrhythmias.
Some people with hypertrophic cardiomyopathy have no symptoms,
and the condition does not affect their lives. Others have
severe symptoms or develop complications such as serious
arrhythmias. A few people with the condition have sudden
cardiac arrest because of dangerous arrhythmias.
Hypertrophic cardiomyopathy can be inherited because of
a gene mutation or develop over time because of high
blood pressure or aging. Often, the cause is unknown.
Restrictive Cardiomyopathy
Restrictive cardiomyopathy tends to mostly affect older
adults. In this cardiomyopathy, the ventricles become stiff
and rigid due to replacement of the normal heart muscle with
abnormal tissue, such as scar tissue. As a result, the ventricles
cannot relax normally and expand to fill with blood, which
causes the atria to become enlarged. Eventually, blood flow
in the heart is reduced, and complications such as heart
failure or arrhythmias occur.
Restrictive cardiomyopathy can occur for no known reason,
or it can develop because the person has another disease.
Some of the diseases that can cause restrictive cardiomyopathy
include hemochromatosis, sarcoidosis,
amyloidosis, and connective tissue disorders. Restrictive
cardiomyopathy also can occur as a result of radiation treatments,
infections, or scarring after surgery.
Arrhythmogenic Right Ventricular Dysplasia
Arrhythmogenic right ventricular dysplasia (ARVD) is a rare
type of cardiomyopathy. ARVD develops when the muscle tissue
in the right ventricle dies and is replaced with scar tissue.
This process causes problems in the heart's electrical signaling,
resulting in arrhythmias. Symptoms include a feeling of strong
or irregular heartbeats (palpitations) and fainting after
exercise.
ARVD usually develops in teens or young adults and is often
the cause of sudden cardiac death in young athletes. ARVD
is thought to be an inherited disease.
Other Names for Cardiomyopathy
- Dilated cardiomyopathy
- Familial dilated cardiomyopathy
- Congestive cardiomyopathy
- Idiopathic dilated cardiomyopathy
- Hypertrophic cardiomyopathy
- Hypertrophic obstructive cardiomyopathy
- Asymmetric septal hypertrophy
- Idiopathic hypertrophic subaortic stenosis
- Familial hypertrophic cardiomyopathy
- Arrhythmogenic right ventricular dysplasia
- Right ventricular dysplasia
- Right ventricular cardiomyopathy
- Restrictive cardiomyopathy
- Arrhythmogenic ventricular cardiomyopathy
To read the rest of this article and related
materials from the National Heart, Lung and Blood Institute,
please click here: http://www.nhlbi.nih.gov/health/dci/Diseases/cm/cm_what.html
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