Restrictive cardiomyopathy is a disorder of the heart muscle in which the walls of the ventricles become stiff, but not necessarily thickened, so they resist normal filling with blood. There is no cure. Treatment aims to relieve symptoms caused by the backup of blood into the lungs and veins of the neck and liver.
The least common of the cardiomyopathies, restrictive cardiomyopathy (RCM) can be idiopathic (its cause is unknown) or secondary to a number of rare cardiac and systemic disorders such as endomyocardial fibrosis (tropical, hypereosinophic syndrome), infiltrative disorders (amyloidosis, sarcoidosis), and rare metabolic disorders (Gaucher's disease, Mucopolysaccharidoses, Fabry's disease, carcinoid syndrome).
Restrictive cardiomyopathy is also described following radiation therapy for some types of cancer.
Patients with the idiopathic form may have a family history of cardiomyopathy. Recent evidence suggests that the disease may be caused by the same genetic abnormalities that result in the more common hypertrophic cardiomyopathy (HCM).
Symptoms and diagnosis
Patients with RCM have signs and/or symptoms of heart failure such as fatigue, shortness of breath, tissue swelling (oedema) and abdominal enlargement. Up to a third of patients may have an embolic complication, such as a blood clot. Abnormal heart rhythms and palpitations are common whatever the underlying cause of the disease.
The diagnosis of RCM is usually based on a physical examination, an electrocardiogram (ECG) and an echocardiogram. Magnetic resonance imaging (MRI) can provide additional information about the structure of the heart. In some patients a precise diagnosis may require catheterisation of the heart to measure pressures and a biopsy of the heart muscle (removal and microscopic examination of a specimen), which may enable the doctor to identify the infiltrating substance.
As the onset of symptoms in RCM is often very subtle, the diagnosis of RCM may be made late in the course of the disease. There is no specific treatment for RCM, and the aims of medical therapy are to improve symptoms of heart failure, treat cardiac rhythm disturbance and to prevent blood clots. Pacemakers are indicated for patients with slow heart rates or 'heart block'. Severe cases may require a heart transplant.
Patients in whom familial disease is suspected should be counselled on this possibility and, where appropriate, family screening should be offered.
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