Home > Encyclopedia of Children's Health > Transposition of the Great Arteries

Definition

Transposition of the great arteries (TGA) is a birth defect causing a fatal condition in which there is a reversal, or switch, in the primary connections of the two main (great) blood vessels to the heart, the aorta and pulmonary artery.

Description

There are two great arteries that transport blood away from the heart, the pulmonary artery and the aorta. Normally, the pulmonary artery carries blood from the right ventricle to the lungs. The aorta carries blood from the left ventricle to the vessels of the rest of the body.

Ordinarily, blood returning to the heart is depleted in oxygen. It goes first to the right atrium of the heart and then to the right ventricle where it is pumped to the lungs. While in the lungs, the blood picks up more oxygen. After the lungs, the blood...