What is a transposition of the great arteries?
Transposition of the great arteries is a congenital heart defect caused when a child’s heart develops incorrectly in the womb. This condition occurs when the heart’s two most important blood vessels—the aorta and the pulmonary artery—are reversed.
In a healthy heart, the aorta pumps oxygen-rich blood to the body, and the pulmonary artery sends blood to the lungs (where the blood absorbs oxygen so that the oxygen-rich blood can then be pumped to the body). With this condition, not enough oxygen-rich blood circulates from the lungs to the body.
Children born with transposition of the great arteries are usually diagnosed shortly after birth, but some may have been diagnosed by fetal ultrasounds before birth. Babies with the condition often have a blue tint to their skin, a sign of cyanosis because oxygen-rich blood has no way to get to the body.
The most common form of transposition
Most infants with D-type transposition will have symptoms and be diagnosed shortly after birth. In this congenital abnormality, no oxygen-rich blood goes to the body and:
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- The aorta and pulmonary artery are switched, but the ventricles developed in the correct place.
- Blood that returns to the heart from the body travels from the right atrium to the right ventricle, where it is pumped out to the body again, without ever going to the lungs.
- Blood from the lungs comes back to the left atrium and then to the left ventricle, where it is pumped back out to the lungs through the pulmonary artery.