Endomyocardial Fibrosis (EMF) – disease of the developing world

Endomyocardial Fibrosis (EMF) – disease of the developing world

Endomyocardial fibrosis (EMF) is a heart muscle disease (cardiomyopathy) seen in the tropical countries, in the developing world. It is a type of restrictive cardiomyopathy, meaning that filling of the ventricles when they relax is restricted due to fibrotic process of endomyocardial region (thickening of the inner lining and the muscles of the heart). It is characterised by fibrosis and obliteration of the ventricular cavity, predominantly involving the right ventricle (lower right chamber of the heart). Isolated involvement of left ventricular inflow region may cause left ventricular inflow and mimic mitral stenosis (narrowing of the valve between the left atrium and left ventricle). But that variety is extremely rare. The common variety involves the right ventricular inflow and body, often obliterating the right ventricular apex. Right ventricular outflow is usually spared. This is the only region of the right ventricle which contracts well in endomyocardial fibrosis and is clinically (on physical examination) evident as right ventricular outflow tract pulsations in the third left intercostal space (to the left of the breastbone or sternum). Right atrium is enlarged in an aneurysmal (huge abnormal dilatation) fashion. Thrombi (clots) and spontaneous echo contrast (a swirling movement in the cavity seen on echocardiography) may be seen in right atrium and ventricle. Severe tricuspid regurgitation (leakage of the valve between the right atrium and right ventricle) is common in endomyocardial fibrosis. Endomyocardial fibrosis is an important cause of low pressure tricuspid regurgitation (Most often, tricuspid regurgitation occurs when the right ventricular pressures are elevation).

RA: right atrium; RV: right ventricle; LA: left atrium; LV: left ventricle; TV: tricuspid valve

Since the right side of the heart is predominantly involved in EMF, they present with elevation of jugular venous pressure (prominent neck veins due to increased back pressure from the right atrium). Liver is enlarged due to the same reason and ascites (fluid in the abdominal cavity) is quite common. Lower limb edema (collection of fluid underneath the skin) is also associated. Ascites is often disproportionate to the edema (ascites precox – more of a feature of constrictive pericarditis, a disease in which the covering of the heart is thickened and often calcified). Patients with left sided involvement can have pulmonary (lung) congestion and pulmonary hypertension (elevated pressures in the blood vessels carrying deoxygenated blood to the lungs).

EMF is seen mostly in tropical countries. It was quite common in Kerala, India, but the prevalence has come down drastically. Sree Chitra Thirunal Institute of Medical Science and Technology Trivandrum has a large surgical experience in EMF. Endocardial resection (surgical removal of a sleeve of tissue in the inner lining of the heart) and tricuspid valve surgery were common in the days when EMF was widely prevalent.