Restrictive Cardiomyopathy
According to the World Health Organization, restrictive cardiomyopathy is defined as "a myocardial disease which is characterized by restrictive filling and reduced diastolic volume of either or both ventricles with normal or near normal systolic function and wall thickness". There is also the possibility of the presence of heavy interstitial fibrosis.
Restrictive Cardiomyopathy
Restrictive Cardiomyopathy can be idiopathic (due to unknown causes) or due to other diseases like endomyocardial disease (which may or may not be further associated with increased eosinophils) or amyloidosis. Restrictive cardiomyopathy (RCM) is perhaps the least occurring of the cardiomyopathies.
The name - restrictive cardiomyopathy - arises from the fact that this disease prevents the degree of expansion of the heart when it is filling with blood though the rhythm of the heartbeat and the heart's ability to contract may be normal. The restricted flow of blood is due to the inability of the chambers of the heart to fill up adequately caused by the stiffness of the walls of the heart chambers. So, the blood that would have been pumped throughout the body cannot be pumped properly and 'backs up', causing damage to the heart muscle.
Restrictive cardiomyopathy can be divided into two types - one in which the heart muscle is damaged by scarring and the second is the one in which the heart muscle is infiltrated by abnormal accumulations of noxious substances (for example, accumulation of iron and iron pigments in patients of hemochromatosis). Other causes of heart muscle damage, causing restrictive cardiomyopathy, are tumors and granuloma tissue (lumpy tissue formed by white blood cells collecting into granules, mostly in response to a chronic inflammation).
The major signs of restrictive cardiomyopathy are shortness of breath and edema (retention of fluid in the tissues, especially the extremities and ankles) along with fainting and chest pain. Heart palpitations and arrhythmia is also quite common in restrictive cardiomyopathy.
In contrast to most other types of cardiomyopathy, in restrictive cardiomyopathy, symptoms do not usually occur when the patient is at rest since the heart is able to meet the body's demand of oxygenated blood but occur during exercise or exertion when the body requires more oxygenated blood.
The electro-cardiogram (ECG) can be used to detect abnormal patterns in the heart's electrical activity but cannot make a specific diagnosis of restrictive cardiomyopathy. Echocardiography may show that the heart has a normal contraction during systole and that the atria are enlarged while an MRI scan can identify deposits of foreign substances like iron or amyloid in the heart muscles. However, a definite diagnosis can be made only by passing a cardiac catheter to measure the chamber pressures and /or by a biopsy.
It has been observed that more than 70% patients of restrictive cardiomyopathy die within a 5-year period of the onset of symptoms since most of the treatments that work on other myopathies fail to work for this condition. Diuretics, if administered, will actually reduce the amount of blood reaching the heart and aggravate the condition. ACE inhibitors, which try to reduce the load on the heart also lower the blood pressure which is not suitable for patients of restrictive cardiomyopathy since the reduced blood pressure reduces the amount of blood going to various parts of the body.
In some cases, treating the underlying cause of restrictive cardiomyopathy prevents the heart damage increasing and may also cause a reversal of damage in certain rare cases.