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.
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