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| Hypertrophic Cardiomyopathy |
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| The second most common form of heart muscle disease is
hypertrophic cardiomyopathy. Physicians sometimes call it
by other names: idiopathic hypertrophic subaortic stenosis
(IHSS), asymmetrical septal hypertrophy (ASH), or
hypertrophic obstructive cardiomyopathy (HOCM).
In hypertrophic cardiomyopathy, the growth and arrangement
of muscle fibers is abnormal, leading to thickened heart
walls. The greatest thickening tends to occur in the left
ventricle (the heart's main pumping chamber), especially in
the septum, the wall that separates the left and right
ventricles. The thickening reduces the size of the pumping
chamber and obstructs blood flow. It also prevents the
heart from properly relaxing between beats and so filling
with blood. Eventually, this limits the pumping action.
Recent research shows that, in more than half of the cases,
hypertrophic cardiomyopathy arises from a genetic
abnormality transmitted by one or both parents. Most of the
remaining cases are idiopathic, having no identifiable
cause. Because of the strong genetic link, a patient's
family members often are evaluated for signs of the disease.
Hypertrophic cardiomyopathy occurs in men and women of all
ages, but its symptoms tend to appear most often in young
adults. Recently, the disease received attention because of
a few well-publicized deaths and fainting spells among young
athletes with the condition. |
| Symptoms |
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| Many patients have no symptoms. Among those who do, the
most common symptom is breathlessness, which results from
the inadequate filling and emptying of the left ventricle.
Another common sign is fainting during physical activity.
This occurs when the brain does not get enough blood,
despite a normal or rapid heartbeat. Patients also may have
palpitations (strong rapid heartbeats), chest pain, or
fatigue, especially during exercise or other forms of
physical exertion.
Unfortunately, in some cases, the first symptom of
hypertrophic cardiomyopathy is sudden death, caused by a
persistently chaotic heartbeat, which is known as
ventricular fibrillation. The heart's lower chambers beat
so chaotically and rapidly that no blood is pumped. Instead
of producing a heartbeat, the heart quivers.
In advanced stages of the disease, patients may have severe
heart failure and its associated symptoms, including fluid
accumulation or congestion. |
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| Course of Disease |
| In most patients, the disease and its symptoms remain
stable. A few people may improve over 5 to 10 years.
Numerous other patients may be restricted in their physical
activity for the rest of their lives, as well as need
continual medical treatment and regular careful evaluation
by a physician.
However, hypertrophic cardiomyopathy can have an
unpredictable course because of the chance of sudden death.
About 4 to 5 percent of patients die each year, most from
cardiac arrest caused by an abnormal heartbeat. |
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| Treatment Regiment |
| Traditionlly, all hypertrophic cardiomyopathy patients were advised to restrict their vigorous physicial activity, since it somtimes causes potentially life-threatening arrhythmias. However, recent studies at the National Heart, Lung and Blood Institute (NHLB) show that patients can be separated into high- and low-risk groups based on results from diagnostic tests of their heart's electrical and blood-flow abnormalities. As a result, some athletes are considered at low risk for dangerous arrhythmias and can resume competive sports. |
| Future Directions for Cardiomyopathy |
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| Future advances in the diagnosis and treatment of
cardiomyopathy depend on a better understanding of the
disease process and why heart muscle is damaged. A lot of
research is under way to identify these processes and
whether they can be halted or even reversed. Much of the
research is conducted at or supported by the NHLBI.
Promising clues came from a team of NHLBI investigators that
discovered some of the genes responsible for hypertrophic
cardiomyopathy. Their work represents an important first
step in understanding how the disease is transmitted and how
it progresses.
Researchers also are trying to determine the best use of
currently available treatments, especially drug therapies.
Drugs useful for other conditions may help treat
cardiomyopathy. For example, drugs effective in treating
high blood pressure also help manage heart failure and
irregular heartbeats.
Additionally, much work has been--and continues to be--done
on identifying factors that increase or decrease a person's
risk of death in cardiomyopathy. Knowing which patients are
at the greatest risk is very important in determining the
best approach to the evaluation and treatment of their
condition.
The development of improved treatments for cardiomyopathy,
however, awaits still more research and a better
understanding of the disease process.
Source: National Institutes of Health |
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