What is restrictive cardiomyopathy?
Restrictive cardiomyopathy, the rarest form of cardiomyopathy, is a condition in which the walls of the lower chambers of the heart (the ventricles) are abnormally rigid and lack the flexibility to expand as the ventricles fill with blood.
The pumping or systolic function of the ventricle may be normal but the diastolic function (the ability of the heart to fill with blood) is abnormal. Therefore, it is harder for the ventricles to fill with blood, and with time, the heart loses the ability to pump blood properly leading to heart failure.
What are the symptoms of restrictive cardiomyopathy?
Many people with restrictive cardiomyopathy have no symptoms or only minor symptoms, and live a normal life. Other people develop symptoms, which progress as heart function worsens.
Symptoms occur at any age and may include:
- Shortness of breath (at first with exercise; but over time it occurs at rest)
- Fatigue (feeling overly tired)
- Inability to exercise
- Swelling of the legs and feet
- Weight gain
- Nausea, bloating, and poor appetite (related to fluid retention)
- Palpitations (fluttering in the chest due to abnormal heart rhythms)
Less common symptoms:
- Fainting (caused by irregular heart rhythms, abnormal responses of the blood vessels during exercise, or no cause may be found)
- Chest pain or pressure (occurs usually with exercise or physical activity, but can also occur with rest or after meals)
What causes restrictive cardiomyopathy?
Restrictive cardiomyopathy is not usually inherited and its cause is often unknown. Known causes include:
- Build-up of scar tissue (idiopathic is the most common cause)
- Build-up of abnormal proteins (amyloidosis) in the heart muscle
- Chemotherapy or chest exposure to radiation
- Excess iron (hemochromatosis) in the heart
- Other systemic diseases (sarcoidosis)
How is restrictive cardiomyopathy diagnosed?
The size of the heart may remain normal with restrictive cardiomyopathy. In some cases, restrictive cardiomyopathy may be confused with constrictive pericarditis, a condition in which the layers of the pericardium (the sac that surrounds the heart) become thickened, calcified and stiff. Constrictive pericarditis prevents the heart muscle from expanding during filling and affects the function of the heart. Certain diagnostic tests may be performed by restrictive cardiomyopathy physicians to rule out pericarditis and confirm the diagnosis of restrictive cardiomyopathy.
Restrictive cardiomyopathy is diagnosed based on medical history, physical exam, and diagnostic tests. Diagnostic work-up may include electrocardiogram, chest X-ray, echocardiogram, exercise stress test, cardiac catheterization, CT scan, MRI and radionuclide studies.
A myocardial biopsy occasionally is done to determine the cause of cardiomyopathy. During a myocardial biopsy, a small tissue sample is taken from the heart and examined under a microscope to determine the cause of symptoms.
How is restrictive cardiomyopathy treated?
Treatment of this condition is difficult. Treatment depends on the cause of this condition. In addition, doctors may recommend lifestyle changes and medications to treat heart failure.
What lifestyle changes are recommended?
- 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.
- Exercise. Your doctor may tell you exercise as tolerated. While exercise is generally good for cardiovascular fitness, some people may experience fatigue and shortness of breath, even with minimal exertion. Therefore, experts recommend that you take frequent breaks, exercise at a time of day where you have the most energy, and start slowly, gradually building up strength and endurance. Heavy weight lifting is not recommended.
To manage heart failure, some people may improve by taking a beta-blocker and ACE inhibitor. If symptoms occur, digoxin, diuretics, and aldosterone inhibitors may be added. If you have an arrhythmia, your doctor may give you a medication to control your heart rate or lessen the occurrence of arrhythmia. Therapy may also be given to treat certain conditions, such as sarcoidosis, amyloidosis, and hemochromatosis.
Your doctor will discuss which medications are best for you.
What are the surgical options?
In some cases, if the condition is severe, a heart transplant may be considered.
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