Transposition of the great arteries is a condition where that the two main blood vessels leaving the heart, the pulmonary artery (which takes blood to the lungs to pick up oxygen) and the aorta (which takes blood from the heart to the body) are swapped over (switched). The pulmonary artery is joined to the left pumping chamber (ventricle) and the aorta to the right pumping chamber (ventricle).
This means that blood flows to the lungs and picks up oxygen but is then pumped back to the lungs instead of travelling around the body. Blood flowing round the body is unable to reach the lungs to pick up oxygen and continues circulating.
Transposition of the great arteries is a form of congenital heart disease – a term used to describe a problem with the heart’s structure and function due to abnormal development before birth.
