Eisenmenger syndrome is the progression of certain congenital heart defects, where an initial left-to-right shunt reverses into a right-to-left shunt. This transition, accompanied by the development of cyanosis, characterizes Eisenmenger syndrome.
Pathological Anatomy
In addition to the primary congenital defects such as ventricular septal defect (VSD), atrial septal defect (ASD), and patent ductus arteriosus (PDA), the following anatomical changes are observed:
- Significant enlargement of the right atrium and right ventricle
- Dilation of the pulmonary artery trunk and its major branches
- Thickened walls of the pulmonary arterioles with narrowed or even obliterated lumens
Pathophysiology
Initially, a large left-to-right shunt causes increased pulmonary blood flow and pulmonary artery pressure. This begins as functional pulmonary vasoconstriction. Persistent hemodynamic changes lead to elevated pressures in the right atrium and right ventricle. Over time, the pulmonary arteries undergo structural narrowing or occlusion, often accompanied by secondary relative pulmonary valve and tricuspid valve regurgitation, particularly in patients with VSD. These changes typically manifest after the age of 20.
A large left-to-right shunt results in increased pulmonary blood flow, progressively raising pulmonary vascular resistance. Over time, functional pulmonary vasoconstriction transitions to structural (organic) changes in the pulmonary vasculature. This reversal of the shunt to a right-to-left flow leads to cyanosis, marking the onset of Eisenmenger syndrome.
Clinical Manifestations
Symptoms
Mild to moderate cyanosis, which worsens with exertion, gradually develops. Patients often exhibit clubbed fingers and toes and report symptoms such as dyspnea, fatigue, and dizziness. Over time, signs of right heart failure may appear.
Signs
Physical examination reveals an enlarged cardiac dullness area, prominent pulsations in the left parasternal region at the 3rd to 4th intercostal spaces, and diminished or absent murmurs associated with the original left-to-right shunt. The second heart sound over the pulmonary valve is accentuated and split. A diastolic murmur and a systolic regurgitant murmur may be heard over the lower left sternal border.
Auxiliary Examinations
Electrocardiography (ECG)
ECG shows right ventricular hypertrophy and strain, along with right atrial enlargement.
Chest X-ray
It shows enlargement of the right ventricle and right atrium, and dilation of the pulmonary artery trunk and its branches (left and right pulmonary arteries). Pulmonary vascular markings may appear reduced, with or without mild pulmonary congestion. Left heart findings depend on the primary defect.
Echocardiography
It demonstrates the primary congenital defect along with pulmonary artery dilation and relative pulmonary valve and tricuspid valve regurgitation, supporting the diagnosis of Eisenmenger syndrome.
Cardiac Catheterization
It identifies the primary defect, confirms bidirectional or right-to-left shunting, and measures pulmonary artery pressure and pulmonary vascular resistance. Vasoreactivity testing can assess the responsiveness of the pulmonary vasculature.
Diagnosis and Differential Diagnosis
The diagnosis is usually straightforward based on the history of late-onset cyanosis, clinical findings, and imaging studies such as chest X-ray and echocardiography. The main differential diagnosis is with congenital cyanotic heart defects, which is generally not challenging.
Treatment
The only effective treatment is combined heart-lung transplantation or lung transplantation with simultaneous repair of the cardiac defect.
Prognosis
Eisenmenger syndrome represents the advanced stage of congenital heart disease where surgical correction is no longer feasible. The prognosis is poor.