Endomyocardial fibrosis


Endomyocardial fibrosis

Description, Causes and Risk Factors:

Thickening of the ventricular endocardium by fibrosis, involving the subendocardial myocardium, and sometimes the atrioventricular valves, with mural thrombosis, leading to progressive right and left ventricular failure with mitral and tricuspid insufficiency; occurs in adults and is endemic in parts of Africa.

Endomyocardial fibrosis (EMF) is a restrictive cardiomyopathy characterized by dense fibrous plaques of the mural endocardium in either one or both of the ventricles of the heart. The disease affects mainly children and young adults who belong to the poorer sections of society and who suffer from varying degrees of malnutrition. EMF has an insidious onset and patients generally present with features of either left-sided or right-sided cardiac failure.

Endomyocardial fibrosis is a progressive disease of unknown origin (idiopathic) that may seriously affect the heart. Its most obvious feature is a gross change in the makeup of the lining of the heart cavities (the endocardium) of one or both of the lower chambers of the heart (the ventricles) leading to the replacement of normal cells with fibrous tissue (fibrosis). This process is progressive and leads to the narrowing (constriction) of the right or left ventricular cavities. It may involve the valves between the chambers of the heart as well as the tendon-like cords that fix the valves to the ventricles (chordae tendineae).

Endomyocardial fibrosis

In EMF, the underlying process produces patchy fibrosis of the endocardial surface of the heart, leading to reduced compliance and, ultimately, restrictive physiology as the endomyocardial surface becomes more generally involved. Endocardial fibrosis principally involves the apices of the right and left ventricles and may affect the atrioventricular valves mainly by tethering the papillary muscles, leading to tricuspid and mitral regurgitation.

The earliest changes of EMF are not well described because most patients do not present with symptoms until relatively late in the clinical course. Olsen described 3 phases of EMF. The first phase involves eosinophilic infiltration of the myocardium with necrosis of the subendocardium and a pathologic picture consistent with acute myocarditis. This is reportedly present in the first 5 weeks of the illness. The second stage, typically observed after 10 months, is associated with thrombus formation over the initial lesions, with a decrement in the amount of inflammatory activity present. Ultimately, after several years of disease activity, the fibrotic phase is reached, when the endocardium is replaced by collagenous fibrosis. This pathomorphologic schema is not observed uniformly and has not been consistently supported by other investigators.

Etiological factors considered important in the past include consumption of large quantities of plantains, deficiency of Vitamin E, lymphatic obstruction and a tropical immunologic syndrome. None of these have been confirmed.

Major current hypotheses about causation of the disease are filarial infection, parasitic eosinophilia and geochemical factors, specifically, the influence of rare earth element cerium in the monazite soil.

The prognosis for endomyocardial fibrosis is relatively poor, although the condition is not universally fatal. There is a 4-year survival rate of 77%.

Symptoms:

Symptoms may include:

    Breathlessness.

  • Cough.

  • Wheezing.

  • Feeding difficulty.

  • Excessive sweating.

  • Failure to thrive.

  • Recurrent chest infections.

In children, remember that severe abdominal pain may indicate coronary insufficiency.Onset may be acute and result in cardiogenic shock or sudden death.

Signs

    Respiratory distress during feeding - tachypnea, grunting, subcostal or intercostal recession.

  • Fever.

  • Pallor (anemia).

  • Peripheral cyanosis.

  • Cardiomegaly - normal or quiet first and second heart sounds, a gallop rhythm with an audible third heart sound.

  • Apical pansystolic murmur.

  • Hepatomegaly.

  • Edema.

  • Rash.

  • Leukocytosis.

Diagnosis:

Complete blood cell count may show anemia and eosinophilia.

Chest radiography: The cardiac silhouette in endomyocardial fibrosis (EMF) may be normal in size, and generalized cardiomegaly is unusual because the ventricles are not typically dilated.The roentgenographic image may exhibit significant enlargement of the atria, and significant right atrial enlargement creates a cardiac silhouette in the shape of the African continent, which is a specific heart shadow sign that has been termed the heart of Africa.

Echocardiography: Echocardiography is a useful tool and the diagnostic modality of choice when making the diagnosis of EMF and has been demonstrated to successfully differentiate EMF and other processes such as rheumatic heart disease and congenital heart disease.The presence and location of fibrosis as determined by echocardiography correlates well with autopsy findings.

Findings include thickening of the inferior and basal left ventricular wall, apical obliteration, and thrombi adherent to the endocardial surface:

    A pericardial effusion is frequently present and may be large.

  • While parameters of diastolic function by Doppler echocardiography tend to correlate with the functional status of the patient, because most patients present with later stages of EMF, a restrictive filling pattern in the left ventricle is most common.

  • Decreased flow propagation velocity (Vp) has been demonstrated in a large percentage of patients with EMF.

  • Color-flow imaging frequently exhibits tricuspid and mitral regurgitation, believed to be due to retraction or adherence of the atrioventricular valvular apparatus. Spectral Doppler analysis of tricuspid regurgitation frequently reflects an increased pulmonary artery systolic pressure.

Angiography: Traditionally, angiography has been considered the criterion standard when making the diagnosis of EMF.Left and right ventriculography exhibits distortion of chamber morphology by fibrosis and obliteration and variable degrees of mitral and tricuspid regurgitation.The mushroom sign has been used to describe the shape of the affected ventricle when the apex is obliterated completely by fibrosis.

Electron beam computed tomography scanning: Features of EMF observed with this modality were described in the mid 1990s.The fibrotic process is delineated as a band of low attenuation within the endocardium.Obliteration of the apex and inflow tract, when present, is also demonstrated.This method reportedly assists in distinguishing EMF from constrictive pericarditis.

Cardiovascular magnetic resonance imaging (C-MRI): Recently, the use of cardiovascular MRI has been shown to demonstrate obliterative changes in the ventricles, atrial dilation, and regurgitant atrioventricular valve lesions in patients with EMF. Recent studies have evaluated the role of contrast-enhanced MRI in detecting myocardial fibrosis, which can potentially be a useful diagnostic tool in patients with EMF.However, clinical use of MRI is limited by access to this technology in endemic areas.

Treatment:

In general, the response to medical therapy is unproven due to lack of well-designed studies. Because most patients with endomyocardial fibrosis (EMF) present long after any possible period of early active myocarditis may have existed, little, if any, role exists for immunosuppressive therapy as is used in some patients with L

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