The Eisenmenger syndrome is a complication of an uncorrected high-flow, high-pressure congenital heart anomaly leading to chronic pulmonary arterial hypertension and shunt reversal.
In general, the shunts that lead to Eisenmenger syndrome share high pressure and high flow . As such the three lesions that account for most cases are:
- ventricular septal defect (VSD)
- most common
- Eisenmenger syndrome in the setting of a VSD is referred to as Eisenmenger complex
- atrioventricular septal defect (AVSD)
- patent ductus arteriosus (PDA)
In this group of patients, gender distribution is equal, and it is uncommon to develop Eisenmenger syndrome before the age of 2 .
In contrast, atrial septal defects (ASD) which are commonly not apparent until adulthood, are generally well tolerated due to the low pressures involved. In this setting Eisenmenger syndrome is uncommon, but when it does occur is more common in females .
In general by the time true Eisenmenger syndrome develops patients are already symptomatic with easy fatigue, dyspnea, chest pain and syncope being common . With shunt reversal, patients become cyanotic and gradually there is a compensatory increase in hematocrit (erythrocytosis). Hemoptysis may also develop due to rupture of small pulmonary arteriolar aneurysms. Furthermore, patients may also develop clubbing, which can be in the hands and feet in the case of Eisenmenger syndrome due to ASD or VSD, or just in the feet ('differential clubbing') when due to PDA .
Exposure of the right heart and pulmonary circulation to increased flow and pressure results in changes including :
- arteriolar medial hypertrophy
- intimal proliferation and fibrosis
- eventual capillary and arteriolar occlusion due to the development of plexiform lesions and necrotizing arteritis.
Concurrently, and in response to increased vascular resistance in the pulmonary vascular bed, the right ventricle hypertrophies, to generate ever increasing pressures. Eventually, a critical balance is reached at which point the pressures generated on the right are higher than those on the left, and the shunt reverses, with de-oxygenated blood passing into the systemic circulation and resulting in cyanosis.
No specific imaging findings can distinguish between a patient with severe pulmonary arterial hypertension and one with superimposed Eisenmenger syndrome. As such the findings are those of pulmonary arterial hypertension.
Cardiac imaging is useful in assessing for the presence of an intracardiac shunt.
Treatment and prognosis
Treatment for Eisenmenger phenomenon has historically been palliative, and closure of the underlying shunt is contra-indicated (remember that right to left shunts have been used to palliative patients with severe pulmonary arterial hypertension) .
More recently some pharmacological agents show the prospect of being beneficial in pulmonary arterial hypertension, including Eisenmenger syndrome (see PAH article). In selected cases combined heart and lung transplantation can be performed.
Although Eisenmenger phenomenon is one of the most severe manifestations of pulmonary arterial hypertension, the prognosis is better than that of idiopathic pulmonary arterial hypertension . Survival, as measured by age reached :
- 30 years of age: 75%
- 40 years of age: 70%
- 55 years of age: 55%
- sudden death
History and etymology
The phenomenon was first described by Victor Eisenmenger (1864-1932) an Austrian physician from Vienna in 1897, in a 32-year-old patient with a large VSD, but his name was only associated with the syndrome in 1958 .
The radiographic differential is essentially that of pulmonary arterial hypertension (see causes of pulmonary arterial hypertension).