Restrictive cardiomyopathy (RCM) is a form of cardiomyopathy in which the walls of the heart are rigid (but not thickened). Thus the heart is restricted from stretching and filling with blood properly. It is the least common of the three original subtypes of cardiomyopathy: hypertrophic, dilated, and restrictive. It should not be confused with constrictive pericarditis, a disease which presents similarly but is very different in treatment and prognosis. Signs and symptoms Untreated hearts with RCM often develop the following characteristics: M or W configuration in an invasive hemodynamic pressure tracing of the RA Square root sign of part of the invasive hemodynamic pressure tracing Of The LV Biatrial enlargement Thickened LV walls (with normal chamber size) Thickened RV free wall (with normal chamber size) Elevated right atrial pressure (>12mmHg), Moderate pulmonary hypertension, Normal systolic function, Poor diastolic function, typically Grade III - IV Diastolic heart failure. Those affected by RCM will experience decreased exercise tolerance, fatigue, jugular venous distention, peripheral edema, and ascites. Arrhythmias and conduction blocks are common. Causes RCM can be caused by genetic or non-genetic factors. Thus it is possible to divide the causes into primary and secondary. The common modern organization is into Infiltrative, storage diseases, non-infiltrative, and endomyocardial etiologies: Genetic DES (desmin) CRYAB (alpha B Crystallin, HSPB5) FLNC (filamin C) Infiltrative Amyloidosis Sarcoidosis Primary hyperoxaluria Storage diseases Fabry disease Gaucher disease Hereditary hemochromatosis Glycogen storage disease Mucopolysaccharidosis type I (Hurler syndrome) Mucopolysaccharidosis type II (Hunter syndrome) Niemann-Pick disease Non-infiltrative Idiopathic Diabetic cardiomyopathy Scleroderma Myofibrillar myopathies Pseudoxanthoma elasticum Sarcomeric protein disorders Werner's syndrome Endomyocardial Carcinoid heart disease Endomyocardial fibrosis Idiopathic Hypereosinophilic syndrome Chronic eosinophilic leukemia Drugs (serotonin, methysergide, ergotamine, mercurial agents, busulfan) Endocardial fibroelastosis Consequence of cancer or cancer therapy Metastatic cancer Drugs (anthracyclines) Radiation The most common cause of restrictive cardiomyopathy is amyloidosis. Mechanism Rhythmicity and contractility of the heart may be normal, but the stiff walls of the heart chambers (atria and ventricles) keep them from adequately filling, reducing preload and end-diastolic volume. Thus, blood flow is reduced, and blood volume that would normally enter the heart is backed up in the circulatory system. In time, restrictive cardiomyopathy patients develop diastolic dysfunction and eventually heart failure. Diagnosis Diagnosis is typically made via echocardiography. Patients will demonstrate normal systolic function, diastolic dysfunction, and a restrictive filling pattern. 2-dimensional and Doppler studies are necessary to distinguish RCM from constrictive pericarditis. Cardiac MRI and transvenous endomyocardial