Restrictive cardiomyopathies are a group of heart muscle diseases in which the heart chambers become increasingly stiff. Eventually, the chambers will lose its flexibility, making it harder for the heart to be adequately filled with blood. Regardless, in restrictive cardiomyopathies the thickness and the volume of the heart chambers remain unchanged.
What causes restrictive cardiomyopathy?
There are two main types of restrictive cardiomyopathy:
- Primary, which is relatively rare. The main causes of primary restrictive cardiomyopathy are unknown, although it may be genetic. It is characterized by scar tissue buildup in the heart chamber walls.
- Secondary, where the main causes are the buildup of abnormal proteins (amyloidosis), iron (hemochromatosis), nodules (sarcoidosis). Other causes may include inflammation of the heart muscle, inherited metabolic disorders (storage diseases), drugs, exposure to radiation, effects of cancer, etc.
What are the main effects of restrictive cardiomyopathy in the body?
Because the walls of the heart chambers are not able to stretch properly, the blood can’t enter the heart normally. Therefore, the pressure in the veins rises, and as a result fluid builds up in lung tissue and air spaces, which can ultimately lead to lung and heart failure.
What are the symptoms of restrictive cardiomyopathy?
The majority of patients don’t show any symptoms, at least in early phases of the disease. However, untreated patients can develop symptoms that worsen over time, due to the increasing inability of the heart chambers to expand properly, ultimately leading to heart failure.
The symptoms patients may notice include:
- Shortness of breath during physical activities
- Fatigue
- Palpitations (fast, pounding heartbeats)
- Irregular heart rhythm
- Chest pain
- Fainting
- Formation of blood clots
Also, if fluid continues to build up in the body, it may lead to:
- Swelling of the abdomen, feet, ankles, legs and neck veins
- Shortness of breath when resting
- Coughing
- Weight gain
- Loss of appetite
- An enlarged liver
How is restrictive cardiomyopathy diagnosed?
Restrictive cardiomyopathy can be very challenging to diagnose. This is partly because symptoms may be absent, and partly because there can be many underlying causes.
Firstly, your doctor will take your medical history, and familiarize themselves with your symptoms. Your family history is also important, because this disease can be inherited. A physical exam may show quieter heart sounds, arrhythmia, or a galloping rhythm (the “third” heart sound) seen in heart failure. Blood tests are not very specific, although they can show signs of the main cause leading to cardiomyopathy.
An electrocardiogram (EKG) will show some changes, such as rhythm irregularity or impaired conduction, although these results are mostly non-specific.
Besides your heart’s shape, an echocardiography also shows your heart activity in real time, which means it can reveal potential motion irregularities. This is important, because this way an echo can distinguish those patients who have restrictive cardiomyopathy from the ones with similar symptoms.
A chest X-ray isn’t that specific, although it may show enlargement of the heart, along with built up fluid in the lungs.
The role of a CT scan and MRI of the heart is to differentiate between potential causes of the disease. With the aid of a CT scan, the doctor can primarily visualize the pericardium, whereas the MRI “sees” the heart muscle itself with more precision.
Although not always necessary, sometimes heart catheterization and biopsy can help in confirming the diagnosis, especially if other methods such as echocardiography show up inconclusive.
How is restrictive cardiomyopathy treated?
Because the disease is generally diagnosed very late, there is no specific therapy, and managing the disease can be very difficult. The aim of cardiomyopathy treatment is to treat the underlying causes, while trying to reduce and control the existing symptoms.
The first thing you need to do is to make some changes in your lifestyle. Your doctor will tell you how much you can exercise, and what types of exercise are the best for your needs. You should always try a slower pace and lower intensity first, and then increase the difficulty. Also, you should restrict your salt input.
Secondly, there are medications that stabilize the heart condition. They are mostly used to control the heart rhythm (anti-arrhythmic, beta blockers, calcium channel blockers), or to reduce the volume of the blood arriving to the heart (diuretics, vasodilators, ACE inhibitors). Blood thinners are useful in case a blood clot is forming. If a certain preexisting condition is diagnosed, such as early amyloidosis or hemochromatosis, your doctor may prescribe you a specific medication regime to treat it.
If the medication you are prescribed turns out to be ineffective, surgical treatment should be considered. This includes:
- Pacemaker implantation (when heart block exists)
- Heart valve replacement
- Heart transplantation (if therapy is not working, or when the disease is terminal)
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