Eisenmenger Syndrome
On this page
Direct answer
Eisenmenger syndrome is pulmonary vascular disease that reverses a long-standing left-to-right shunt into right-to-left flow, producing cyanosis. The shunt is commonly a ventricular septal defect, atrial septal defect or patent ductus arteriosus. Because the pulmonary vascular obstruction is irreversible, surgical closure of the defect is contraindicated.
What you must remember
- Mechanism: progressive pulmonary vascular remodelling raises pulmonary resistance until it exceeds systemic resistance, reversing the shunt.
- Clinical signs: central cyanosis, clubbing, a loud second heart sound and a right ventricular heave.
- Secondary erythrocytosis: raised haematocrit compensates for hypoxaemia but increases blood viscosity, with a risk of stroke and headache.
- Gout and renal disease: hyperuricaemia and renal impairment are common in long-standing disease.
- Complications: haemoptysis, paradoxical embolism with brain abscess, arrhythmias, syncope and sudden death.
- Pregnancy: maternal mortality is high, so pregnancy is discouraged and contraception counselling is essential.
- Management principles: avoid dehydration, correct iron deficiency, prophylax against endocarditis and use approved pulmonary hypertension drugs in specialist centres.
Sequence from shunt to shunt reversal
Eisenmenger physiology develops over years in a predictable sequence. The steps below show how a left-to-right shunt becomes a fixed, high-resistance circuit.
- Shunt and flow: a large left-to-right shunt delivers extra flow to the pulmonary circulation, which is initially well tolerated. Symptoms are often absent in early childhood, which is why the shunt can go unnoticed.
- Remodelling: chronic high flow thickens pulmonary arterioles through medial hypertrophy and intimal fibrosis, eventually producing plexiform lesions.
- Reversal: when pulmonary resistance exceeds systemic resistance, blood crosses the defect from right to left, causing cyanosis. The direction of shunt depends on the balance of resistances rather than on the size of the defect alone.
- Compensation: erythrocytosis raises haemoglobin, and clubbing follows long-standing hypoxaemia.
- Management: avoid dehydration and do not close the shunt, correct iron deficiency and use approved pulmonary hypertension drugs in specialist units.
- Advanced options: heart-lung or lung transplantation is considered when medical therapy fails.
Where the exam tries to catch you
Eisenmenger questions reward the principle that the shunt must be left alone. Watch for these traps.
- Trap: Closing a large VSD to reduce the child's cyanosis. Correct: Once shunt reversal is established, closure raises right ventricular load and can be fatal, so it is contraindicated.
- Trap: Performing routine venesection for every high haematocrit. Correct: Venesection is reserved for symptomatic hyperviscosity, and iron deficiency should be corrected rather than worsened.
- Trap: Dismissing headache in an Eisenmenger patient as benign. Correct: Erythrocytosis and paradoxical embolism can cause stroke or brain abscess, so headache needs urgent review.
Frequently asked questions
Why is surgical closure contraindicated in Eisenmenger syndrome?
Closing the shunt in Eisenmenger syndrome removes the outlet for a right ventricle that is already working against fixed pulmonary hypertension. This raises right heart pressure and can precipitate sudden death, so the defect is deliberately left in place.
Which pulmonary hypertension drugs are used in Eisenmenger syndrome?
Approved pulmonary arterial hypertension agents, including endothelin receptor antagonists and phosphodiesterase-5 inhibitors, are used in Eisenmenger syndrome in specialist centres. Choice depends on the child's haemodynamic profile and on expert advice rather than a single standard protocol.
What causes clubbing in Eisenmenger syndrome?
Clubbing in Eisenmenger syndrome follows long-standing hypoxaemia from right-to-left shunting. Its precise mechanism is not fully settled, but it reliably marks chronic cyanosis and is seen alongside secondary erythrocytosis.
Why is brain abscess a risk in Eisenmenger syndrome?
Paradoxical embolism through the shunt lets infected or thrombotic material bypass the lungs and reach the brain. Erythrocytosis and dental sepsis raise the risk further, so brain abscess should be considered in any patient with headache, fever or a focal deficit.