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Dilated Cardiomyopathy
Dilated cardiomyopathy, a common form of cardiomyopathy, is characterized by an overall enlargement or stretching of the heart muscle accompanied by a decrease in the heart's ability to contract. Dilated cardiomyopathy usually begins with stretching of the left ventricle; in some cases, the right ventricle may become affected as well. Dilated cardiomyopathy can lead to heart failure, a decrease in the heart's ability to contract and pump blood out into the arteries of the body. Other complications include disturbances in the heart's electrical system known as arrhythmias, blood clots forming within the heart, and sudden death, any of which can occur at any stage of the disease.
Although it can occur in infants and the elderly, dilated cardiomyopathy occurs most frequently between the ages of 20 and 60. It is three times more common in men than women and more common in African-Americans than Caucasians.
The progression of dilated cardiomyopathy can be rapid; some studies have found that 50 percent of deaths due to dilated cardiomyopathy occur within two years of diagnosis, although the risk of dying within one year for all patients with heart failure symptoms is about 12 percent. In general, the worse the symptoms, the worse the outlook. For example, a patient with mild breathlessness during significant exertion may have a 5 percent chance of dying within a year, while a person who has these symptoms while sitting in a chair may have a 30-50 percent risk of dying within a year.
When cardiomyopathy is caused by coronary artery disease (CAD) it is known as ischemic cardiomyopathy, the most common type of cardiomyopathy. People with ischemic cardiomyopathy often develop the same signs and symptoms as those with other forms of dilated cardiomyopathy. However, with ischemic cardiomyopathy, the symptoms are caused by narrowed or blocked coronary blood vessels restricting blood flow and oxygen to the heart tissue, which damages the heart muscle. Even though the signs and symptoms are the same, ischemic cardiomyopathy has traditionally been considered separate from dilated cardiomyopathy because coronary artery disease typically causes localized damage to the heart as opposed to the generalized damage of all heart cells associated with dilated cardiomyopathy. More importantly, the damage to heart muscle associated with ischemic cardiomyopathy can be reversed in some patients by opening the blockages caused by CAD. For this reason, almost all patients with a new diagnosis of dilated cardiomyopathy undergo a cornary angiogram to evaluate the condition of their coronary arteries.
Dilated cardiomyopathies can be caused by many other conditions or the cause may never be identified. In the United States, dilated cardiomyopathies other than ischemic cardiomyopathy account for 50,000 hospitalizations and over 10,000 deaths annually--and these statistics are on the rise. Other common types of dilated cardiomyopathy include:
Inflammatory cardiomyopathy can develop as the result of viral, bacterial, or autoimmune infection as well as myocardial inflammatory disease. Some of the infectious and inflammatory conditions that have been linked to inflammatory dilated cardiomyopathy are lymphocytic and giant cell myocarditis, Lyme disease, HIV, mumps, influenza, Epstein-Barr, and hepatitis B and C.
Familial (genetic) cardiomyopathy accounts for roughly 20 percent of all cases of dilated cardiomyopathy where no other cause can be identified. The details of the genetic link are not well understood but it's clear there is a genetic prediposition to developing dilated cardiomyopathy in some families. As such, evaluation of all first-degree relatives to rule out a "silent" familial cardiomyopathy is recommended for people whose dilated cardiomyopathy can not be attributed to a specific cause.
Alcoholic cardiomyopathyusually begins to develop after about 10 years of heavy alcohol consumption.
Toxic cardiomyopathy may develop after exposure to certain toxins including cocaine, methamphetamines and some chemotherapy drugs.
Peripartum cardiomyopathy can develop in women during the last trimester of pregnancy or within five months after childbirth. Women often recover completely from peripartum cardiomyopathy, but it may recur with future pregnancies.
Valvular cardiomyopathy can develop when the workload on the heart in increased due to a malfunctioning heart valve.
Tachycardia-induced cardiomyopathy, caused by chronic rapid heart rate, is important to identify because the symptoms of heart failure can be reversed in these people by treating the arrhythmia. Learn more about arrhythmias here.
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