What Is Dilated Cardiomyopathy?
Dilated cardiomyopathy (DCM) is the most common type of nonischemic cardiomyopathy. In dilated cardiomyopathy, the heart's ability to pump blood is decreased because the heart's main pumping chamber, the left ventricle, is enlarged, dilated and weak. At first, the chambers of the heart respond by stretching to hold more blood to pump through the body. This helps to strengthen the heart's contraction and keep the blood moving for a short while. With time, the heart muscle walls weaken and are not able to pump as strongly. The kidneys often respond by retaining fluid (water) and sodium. If fluid builds up in the legs, ankles, feet, lungs or other organs, the body becomes congested, and congestive heart failure is the term used to describe this condition.
What are the symptoms of DCM?
Many people with dilated cardiomyopathy have no symptoms or only minor symptoms. Other people develop symptoms, which may progress as heart function worsens.
Symptoms of dilated cardiomyopathy can occur at any age and may include:
- Shortness of breath
- Swelling of the legs and feet
- Fatigue (feeling overly tired), inability to exercise, or carry out activities as usual
- Weight gain, cough and congestion related to fluid retention
- Palpitations or fluttering in the chest due to abnormal heart rhythms (arrhythmia)
- Dizziness or lightheadedness
- Fainting (caused by irregular heart rhythms, abnormal responses of the blood vessels during exercise, without apparent cause)
- Blood clots due to blood flowing more slowly through the body. If a blood clot breaks off, it can be carried to the lungs (pulmonary emboli), kidney (renal emboli), brain (cerebral emboli or stroke), or limbs (peripheral emboli).
What causes DCM?
- Most cases of dilated cardiomyopathy are idiopathic (an exact cause is not known)
- Sometimes a viral illness may be responsible
- Occasionally it may be inherited (familial cardiomyopathy)
- Heart valve disease (valvular cardiomyopathy)
- Alcoholism (heavy drinking, alcoholic cardiomyopathy)
- Drug abuse or taking d rugs that are toxic to the heart
- Thyroid disease
- Women after childbirth (peripartum cardiomyopathy).
When there is no known cause, the condition is called idiopathic dilated cardiomyopathy. About 1/3 of patients with idiopathic DCM have a family history, called familial dilated cardiomyopathy (ref). Familial DCM is a genetic condition. In rare autosomal dominant inheritance patterns (at least two family member have idiopathic DCM), first degree relatives (parents, siblings, children) have a 50 percent chance of inheriting the condition, and may benefit from risk screening or follow-up by a physician.
How is DCM diagnosed?
DCM is diagnosed based on your medical history, physical exam, and other tests. Specific tests may include blood tests, electrocardiogram (ECG), chest X-ray, echocardiogram, exercise stress test, cardiac catheterization, CT scan, MRI scan, and radionuclide studies.
Occasionally, a myocardial biopsy may be performed to determine the cause of cardiomyopathy. During a myocardial biopsy, small tissue samples are taken from the heart and examined under a microscope to determine the cause of the cardiomyopathy.
Family members with familial idiopathic DCM should be screened for DCM. Testing would be the same as mentioned above (medical history, physical exam, ECG, echocardiogram, etc.). Genetic testing is available to identify abnormal genes; researchers are looking into identifying abnormal genes. You should speak to your doctor about family screening.
How is DCM treated?
Treatment of cardiomyopathy is aimed at treating the cause of heart failure whenever possible. Once diagnosed, the primary goal is to improve cardiac function and reduce symptoms. Patients usually take several medications to treat DCM. Doctors also recommend lifestyle changes that decrease symptoms and hospitalizations, and improve quality of life.
Medications are used for two reasons:
- To improve cardiac function
- To treat symptoms and prevent complications
To manage heart failure, most people improve by taking a beta-blocker and ACE inhibitor even when not having symptoms. If symptoms occur and/or worsen,digoxin, diuretics, and aldosterone inhibitors may be added. Other medications will be added as needed. For example, if you have an arrhythmia, your doctor may give you a medication to control your heart rate or lessen the occurrence of arrhythmia. Or, blood thinners may be used to prevent blood clots from occurring. Your doctor will discuss what medications are best for you.
Learn more about medications
- Diet. Once you develop symptoms such as shortness of breath or fatigue, you should restrict your intake of salt (sodium) to 2,000 to 3,000 mg per day. Follow this low-sodium diet even when your symptoms seem to have subsided. Most salt ingested comes from processed food. In addition to removing the salt shaker from the table and when cooking, read all food labels for sodium content and serving size so you can keep track of your sodium intake. Learn more about nutrition guidelines for heart failure.
- Exercise. Your doctor will tell you if you may exercise or not. Most people with cardiomyopathy are encouraged to do non-competitive aerobic exercise. Heavy weight lifting may not be recommended.
- Learn more about heart failure lifestyle changes
- Cardiac Resynchronization Therapy (CRT, such as biventricular pacing) : In some patients with advanced heart failure, biventricular pacing (a pacemaker that senses and initiates heartbeats in the right and left ventricle) improves survival, reduces symptoms and increases exercise capacity or tolerance. For people with heart block or some bradycardias (slow heart rates), this pacemaker will also serve to maintain an adequate heart rate.
- Implantable Cardioverter Defibrillators (ICD) : ICDs are suggested for people at risk for life-threatening ventricular arrhythmias or sudden cardiac death. The ICD constantly monitors the heart rhythm. When it detects a very fast, abnormal heart rhythm, it delivers energy (shock) to the heart muscle to cause the heart to beat in a normal rhythm again.
Both devices may be combined in a single unit, usually labeled CRT-D.
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