A condition in which deoxygenated blood flows directly back into the circulation instead of through the lungs. This is caused by an abnormal connection between the rights and left sides of the heart and to pulmonary hypertension (in which there is unusually high blood pressure in the arteries that supply the lungs). The resultant hypoxia (lack of oxygen in the blood) creates cyanosis (bluish colouration of the skin) , difficulty in breathing and fainting.
Eisenmenger complex arises most commonly in those who have certain uncorrected congenital heart defects, for example ventricular septal defect.
The diagnosis of Eisenmenger complex can be confirmed by cardiac catheterisation (the insertion, under X-ray control, of a thin tube into the heart via a blood vessel). After the condition has developed, surgical correction of the original defect cannot help. Drug treatment can help control the symptoms but ultimately, a heart-lung transplant may be needed.