Eisenmenger Syndrome

Eisenmenger syndrome occurs when blood flows from the right side of the heart to the left across a structural heart lesion, bypassing the lungs. There are three underlying lesions that can result in Eisenmenger syndrome:

  • Atrial septal defect
  • Ventricular septal defect
  • Patent ductus arteriosus

Eisenmenger syndrome can develop after 1-2 years with large shunts or in adulthood with small shunts. It can develop more quickly during pregnancy, so women with a history of having a “hole in the heart” need an echo and close monitoring by a cardiologist during pregnancy.



Normally when there is a septal defect blood will flow from the left side of the heart to the right. This is because the pressure in the left side is greater than in the right. Remember, the left ventricle has to pump blood through the entire body, whereas the right ventricle simply has to fill the lungs. A left to right shunt means blood still travels to the lungs and gets oxygenated, so the patient does not become cyanotic.

Over time the extra blood flowing into the right side of the heart and the lungs increases the pressure in the pulmonary vessels. This leads to pulmonary hypertension. When the pulmonary pressure exceeds the systemic pressure, blood begins to flow from the right side of the heart to the left across the septal defect. This is a right to left shunt. Essentially it becomes easier for the right side of the heart to pump blood across the defect into the left side of the heart compared with pumping blood into the lungs. This causes deoxygenated blood to bypass the lungs and enter the body. This causes cyanosis.

Cyanosis refers to the blue discolouration of skin relating to a low level of oxygen saturation in the blood. The bone marrow will respond to low oxygen saturations by producing more red blood cells and haemoglobin to increase the oxygen carrying capacity of the blood. This leads to polycythaemia, which is a high concentration of haemoglobin in the blood. Polycythaemia gives patients a plethoric complexion. A high concentration of red blood cells and haemoglobin make the blood more viscous, making patients more prone to developing blood clots.

Examination Findings

Examination findings associated with pulmonary hypertension:

  • Right ventricular heave: the right ventricle contracts forcefully against increased pressure in the lungs
  • Loud P2: loud second heart sound due to forceful shutting of the pulmonary valve
  • Raised JVP
  • Peripheral oedema

Examination findings related to the underlying septal defect:

  • Atrial septal defect: mid-systolic, crescendo-decrescendo murmur loudest at the upper left sternal border
  • Ventricular septal defect: pan-systolic murmur loudest at the left lower sternal border
  • Patent ductus arteriosus: continuous crescendo-decrescendo “machinery” murmur
  • Arrhythmias

Findings related to the right to left shunt and chronic hypoxia:

  • Cyanosis
  • Clubbing
  • Dyspnoea
  • Plethoric complexion (a red complexion related to polycythaemia)



Eisenmenger syndrome reduces life expectancy by around 20 years compared with healthy individuals. The main causes of death are heart failure, infection, thromboembolism and haemorrhage. The mortality can be up to 50% in pregnancy.



Ideally the underlying defect should be managed optimally or corrected surgically to prevent the development of Eisenmenger syndrome.

Once the pulmonary pressure is high enough to cause the syndrome, it is not possible to medically reverse the condition. The only definitive treatment is a heart-lung transplant, however this has a high mortality.

Patients with Eisenmenger syndrome will be closely followed up by a specialist. Medical management involves:

  • Oxygen can help manage symptoms but does not affect overall outcomes
  • Treatment of pulmonary hypertension, for example using sildenafil
  • Treatment of arrhythmias
  • Treatment of polycythaemia with venesection
  • Prevention and treatment of thrombosis with anticoagulation
  • Prevention of infective endocarditis using prophylactic antibiotics


Last updated July 2019