Eisenmengers syndrome overview

# Overview
Eisenmenger's syndrome or Eisenmenger's reaction is defined as the process in which a left-to-right shunt in the heart causes increased flow through the pulmonary vasculature, which leads to pulmonary hypertension, which finally causes increased pressures in the right side of the heart and reversal of the shunt into a right-to-left shunt. This right to left shunt causes the patient to become cyanotic. Thus, Eisenmenger's syndrome is said to develop when there is a pulmonary artery disease, right-to-left heart shunting and cyanosis. Victor Eisenmenger first described the syndrome in 1897 in a patient who presented with dyspnea and cyanosis since infancy. Since then, advances in the medical treatment of pulmonary hypertension improved the survival of Eisenmenger's syndrome. Eisenmenger's syndrome can be classified according to the underlying congenital heart disease into simple and complex. Histologically, six stages were identified by Heath and Edwards, ranging from reversible to irreversible and terminal. The progression of a heart defect to Eisenmenger's syndrome depends on the size of left to right shunt, severity of pulmonary vascular disease, and type of defect. The left-to-right shunt at the start increases the pulmonary vascular flow and leads to pulmonary artery hypertension. This causes damage to the delicate pulmonary capillaries, creating scars and fibrous tissue. This leads to hypoxemia, which is compensated by increased RBCs production, leading to polycythemia and hyperviscosity syndrome. Eventually, the building pressure in the pulmonary circulation will cause shunt reversal and development of Eisenmenger's syndrome. Eisenmenger's syndrome is causes by cardiac defects that shunt blood heading to the systemic circulation back into the pulmonary circulation. These defects include ventricular septal defect, atrial septal defect, atrioventricular canal defect, patent ductus arteriosus, and truncus arteriosus. Eisenmenger's syndrome should be differentiated from idiopathic pulmonary hypertension, pulmonary infarction, respiratory failure, tricuspid atresia, persistent truncus arteriosus, and other congenital heart diseases. The incidence and prevalence of Eisenmenger's syndrome has been decreasing gradually over the years. In the general population, the prevalence decreased from 24.6 to 11.9/million inhabitants in 2012. About 8% of patents with congenital heart diseases develop Eisenmenger's syndrome. The mortality rate of Eisenmenger's syndrome is about 27%. The risk of Eisenmenger's syndrome increases in patients with large cardiac defects or who live in developing countries due to poor healthcare access. The common risk factors for Eisenmenger's syndrome include genetic mutations, exposure to rubella virus, and drug and alcohol abuse during pregnancy. Less common risk factors include poor healthcare access and patients in developing countries. There are currently no guidelines on using echocardiography to screen patients with CHD for the presence of pulmonary arterial hypertension. However, some parameters are recommended as pedictive for the development of pulmonary arterial hypertension, including peak tricuspid regurgitation velocity, ventricular basal diameter ratio, systolic and/or diastolic ventricular eccentricity index, RV outflow Doppler acceleration time, pulmonary artery diameter, and inferior vena cava inspiratory collapse. Eisenmenger's syndrome passes through different stages, including the causative  left-to-right shunt, development of pulmonary hypertension, polycythemia, and shunt reversal. The complications of Eisenmenger's syndrome include intracranial hemorrhage, stroke, congestive heart failure, angina pectoris, hyperviscosity syndrome, infection (cerebral abscess), renal failure, and sudden death. How well the infant or child does depends onwhether another medical condition is present and the age at which high blood pressure develops in the lungs. Patients with Eisenmenger's syndrome can live 20 to 50 years. Echocardiography is the first line diagnostic modality of Eisenmenger's syndrome. Findings on an echocardiography suggestive of Eisenmenger's syndrome include underlying cardiac lesion responsible for the shunt, direct of the shunt, and elevated right ventricular systolic and pulmonary artery diastolic pressures. Patients with Eisenmenger's syndrome pass through the following stages: An underlying heart defect that initially allows a left-to-right shunt between the left and right sides of the heart, then the development of pulmonary hypertension, then polycythemia, an increase in the number of red blood cells, and finally, a reversal of the left-to-right shunt so that there is a right-to-left shunt. The common symptoms of Eisenmenger's syndrome include dyspnea, syncope, hemoptysis, chest pain, dizziness, fatigue, and dyspnea. The general examination of patients with Eisenmenger's syndrome may show cyanosis, dermal changes, clubbing, peripheral edema, and abdominal swelling. Cardiac examination may show A wave dominant jugular venous pulse, right ventricular heave, high-pitched early diastolic murmur of pulmonary insufficiency, right-sided S4, pulmonary ejection click, single palpable S2, and loud P2. The laboratory findings of patients with Eisenmenger's syndrome include erythrocytosis, iron deficiency, increased bleeding time, increased blood uric acid and conjugated bilirubin concentrations, as well as mixed respiratory and metabolic acidosis. Eisenmenger's patients may show some ECG findings, including right axis deviation (ventricular hypertrophy), ST changes (Right ventricular or biventricular hypertrophy), P Pulmonale (Right atrial hypertrophy), tall R wave in V1 and deep S wave in V6, and microvolt T-wave alternans. Chest X-ray of patients with Eisenmenger's syndrome may show cardiomegaly, right ventricular or biventricular enlargement, right atrial or biatrial enlargement, and pulmonary vascular plethora. Echocardiography is the first line diagnostic modality of Eisenmenger's syndrome. Findings on an echocardiography suggestive of Eisenmenger's syndrome include underlying cardiac lesion responsible for the shunt, direct of the shunt, and elevated right ventricular systolic and pulmonary artery diastolic pressures. Computed tomography can be helpful as a diagnostic tool in conditions where the echocardiographic findings are inconclusive. The findings on CT scan may include large main pulmonary artery, ventricular septal defect, and right ventricular hypertrophy. Magnetic resonance imaging can be helpful as a diagnostic tool in conditions where the echocardiographic findings are inconclusive. The following can be observed on MRI examination of Eisenmenger's syndrome patients: Magnitude and direction of the cardiac shunt, reduced systolic function of the cardiac ventricles, and brain diffusion changes on brain MRI. Cardiac catheterization is useful in patients with Eisenmenger's syndrome in terms of assessing the severity of pulmonary hypertension, coexisting congenital anomalies, degree and direction of shunting, ventricular function, pulmonary artery pressure and flow, and calculation of pulmonary vascular resistance. There are no other diagnostic studies associated with Eisenmenger's syndrome. If surgical intervention is not available, treatment is mostly palliative. It includes anticoagulants, pulmonary vasodilators such as bosentan, PGE 5 inhibitor, prostacyclin, antibiotic prophylaxis to prevent endocarditis, phlebotomy to treat polycythemia, and maintaining proper fluid balance. Congenital heart defects should undergo surgical repair before progression to Eisenmenger's syndrome. Once the condition develops into Eisenmenger's syndrome, no surgical cure is available except for heart and lung transplantation. However, palliative interventions (as creation of an artificial ASD) may prolong the lifespan and improve the quality of life. Surgery as early as possible to correct the heart defect can prevent Eisenmenger's syndrome. Due to the irreversible nature of Eisenmenger's syndrome, there are no established measures for the secondary prevention.

# Historical Perspective
Victor Eisenmenger first described the syndrome in 1897 in a patient who presented with dyspnea and cyanosis since infancy. Since then, advances in the medical treatment of pulmonary hypertension improved the survival of Eisenmenger's syndrome.

# Classification
Eisenmenger's syndrome can be classified according to the underlying congenital heart disease into simple and complex. Histologically, six stages were identified by Heath and Edwards, ranging from reversible to irreversible and terminal.

# Pathophysiology
The progression of a heart defect to Eisenmenger's syndrome depends on the size of left to right shunt, severity of pulmonary vascular disease, and type of defect. The left-to-right shunt at the start increases the pulmonary vascular flow and leads to pulmonary artery hypertension. This causes damage to the delicate pulmonary capillaries, creating scars and fibrous tissue. This leads to hypoxemia, which is compensated by increased RBCs production, leading to polycythemia and hyperviscosity syndrome. Eventually, the building pressure in the pulmonary circulation will cause shunt reversal and development of Eisenmenger's syndrome.

# Causes
Eisenmenger's syndrome is causes by cardiac defects that shunt blood heading to the systemic circulation back into the pulmonary circulation. These defects include ventricular septal defect, atrial septal defect, atrioventricular canal defect, patent ductus arteriosus, and truncus arteriosus.

# Differentiating Eisenmenger's syndrome from Other Diseases
Eisenmenger's syndrome should be differentiated from idiopathic pulmonary hypertension, pulmonary infarction, respiratory failure, tricuspid atresia, persistent truncus arteriosus, and other congenital heart diseases.

# Epidemiology and Demographics
The incidence and prevalence of Eisenmenger's syndrome has been decreasing gradually over the years. In the general population, the prevalence decreased from 24.6 to 11.9/million inhabitants in 2012. About 8% of patents with congenital heart diseases develop Eisenmenger's syndrome. The mortality rate of Eisenmenger's syndrome is about 27%. The risk of Eisenmenger's syndrome increases in patients with large cardiac defects or who live in developing countries due to poor healthcare access.

# Risk Factors
The common risk factors for Eisenmenger's syndrome include genetic mutations, exposure to rubella virus, and drug and alcohol abuse during pregnancy. Less common risk factors include poor healthcare access and patients in developing countries.

# Screening
There are currently no guidelines on using echocardiography to screen patients with CHD for the presence of pulmonary arterial hypertension. However, some parameters are recommended as pedictive for the development of pulmonary arterial hypertension, including peak tricuspid regurgitation velocity, ventricular basal diameter ratio, systolic and/or diastolic ventricular eccentricity index, RV outflow Doppler acceleration time, pulmonary artery diameter, and inferior vena cava inspiratory collapse.

# Natural History, Complications, and Prognosis
Eisenmenger's syndrome passes through different stages, including the causative  left-to-right shunt, development of pulmonary hypertension, polycythemia, and shunt reversal. The complications of Eisenmenger's syndrome include intracranial hemorrhage, stroke, congestive heart failure, angina pectoris, hyperviscosity syndrome, infection (cerebral abscess), renal failure, and sudden death. How well the infant or child does depends onwhether another medical condition is present and the age at which high blood pressure develops in the lungs. Patients with Eisenmenger's syndrome can live 20 to 50 years.

# Diagnosis

## Diagnostic Study of Choice
Echocardiography is the first line diagnostic modality of Eisenmenger's syndrome. Findings on an echocardiography suggestive of Eisenmenger's syndrome include underlying cardiac lesion responsible for the shunt, direct of the shunt, and elevated right ventricular systolic and pulmonary artery diastolic pressures.

## History and Symptoms
Patients with Eisenmenger's syndrome pass through the following stages: An underlying heart defect that initially allows a left-to-right shunt between the left and right sides of the heart, then the development of pulmonary hypertension, then polycythemia, an increase in the number of red blood cells, and finally, a reversal of the left-to-right shunt so that there is a right-to-left shunt. The common symptoms of Eisenmenger's syndrome include dyspnea, syncope, hemoptysis, chest pain, dizziness, fatigue, and dyspnea.

## Physical Examination
The general examination of patients with Eisenmenger's syndrome may show cyanosis, dermal changes, clubbing, peripheral edema, and abdominal swelling. Cardiac examination may show A wave dominant jugular venous pulse, right ventricular heave, high-pitched early diastolic murmur of pulmonary insufficiency, right-sided S4, pulmonary ejection click, single palpable S2, and loud P2.

## Laboratory Findings
The laboratory findings of patients with Eisenmenger's syndrome include erythrocytosis, iron deficiency, increased bleeding time, increased blood uric acid and conjugated bilirubin concentrations, as well as mixed respiratory and metabolic acidosis.

## Electrocardiogram
Eisenmenger's patients may show some ECG findings, including right axis deviation (ventricular hypertrophy), ST changes (Right ventricular or biventricular hypertrophy), P Pulmonale (Right atrial hypertrophy), tall R wave in V1 and deep S wave in V6, and microvolt T-wave alternans.

## X-ray
Chest X-ray of patients with Eisenmenger's syndrome may show cardiomegaly, right ventricular or biventricular enlargement, right atrial or biatrial enlargement, and pulmonary vascular plethora.

## Echocardiography and Ultrasound
Echocardiography is the first line diagnostic modality of Eisenmenger's syndrome. Findings on an echocardiography suggestive of Eisenmenger's syndrome include underlying cardiac lesion responsible for the shunt, direct of the shunt, and elevated right ventricular systolic and pulmonary artery diastolic pressures.

## CT scan
Computed tomography can be helpful as a diagnostic tool in conditions where the echocardiographic findings are inconclusive. The findings on CT scan may include large main pulmonary artery, ventricular septal defect, and right ventricular hypertrophy.

## MRI
Magnetic resonance imaging can be helpful as a diagnostic tool in conditions where the echocardiographic findings are inconclusive. The following can be observed on MRI examination of Eisenmenger's syndrome patients: Magnitude and direction of the cardiac shunt, reduced systolic function of the cardiac ventricles, and brain diffusion changes on brain MRI.

## Other Imaging Findings
Cardiac catheterization is useful in patients with Eisenmenger's syndrome in terms of assessing the severity of pulmonary hypertension, coexisting congenital anomalies, degree and direction of shunting, ventricular function, pulmonary artery pressure and flow, and calculation of pulmonary vascular resistance.

## Other Diagnostic Studies
There are no other diagnostic studies associated with Eisenmenger's syndrome.

# Treatment

## Medical Therapy
If surgical intervention is not available, treatment is mostly palliative. It includes anticoagulants, pulmonary vasodilators such as bosentan, PGE 5 inhibitor, prostacyclin, antibiotic prophylaxis to prevent endocarditis, phlebotomy to treat polycythemia, and maintaining proper fluid balance.

## Surgery
Congenital heart defects should undergo surgical repair before progression to Eisenmenger's syndrome. Once the condition develops into Eisenmenger's syndrome, no surgical cure is available except for heart and lung transplantation. However, palliative interventions (as creation of an artificial ASD) may prolong the lifespan and improve the quality of life.

## Primary Prevention
Surgery as early as possible to correct the heart defect can prevent Eisenmenger's syndrome.

## Secondary Prevention
Due to the irreversible nature of Eisenmenger's syndrome, there are no established measures for the secondary prevention.