May also be called: Complete Transposition of the Great Arteries; Transposition of the Great Vessels; Transposition of the Great Arteries

Complete transposition (trans-puh-ZIH-shun) of the great vessels is a heart defect where the aorta and the pulmonary artery (called the "great vessels" or "great arteries") are reversed, causing the heart to work incorrectly and preventing blood from getting oxygen.

More to Know

The human heart has four chambers: the right atrium, left atrium, right ventricle, and left ventricle. In a healthy heart, oxygen-poor blood from the body enters the heart through the right atrium. Blood then flows to the right ventricle and is pumped to the lungs through the pulmonary artery to pick up oxygen. The oxygen-rich blood then comes back to the heart through the left atrium. The blood flows to the left ventricle and takes the oxygen to the body through the aorta.

When someone has a complete transposition of the great vessels, the pulmonary artery and the aorta are switched so that the aorta is on the right side of the heart and receives oxygen-poor blood, which is sent right back out to the body without getting more oxygen. The pulmonary artery is on the left side of the heart, receives oxygen-rich blood, and sends it back to the lungs again. So, oxygen-rich blood cannot get to the body.

Babies with complete transpositions of the great vessels often appear very blue and have low oxygen levels in the bloodstream. They may have trouble feeding and problems breathing. Without treatment, transposition can be life threatening.

Keep in Mind

Treatment for complete transposition of the great vessels usually involves a surgical procedure called an arterial switch, where the aorta is attached to the left ventricle and the pulmonary artery is attached to the right ventricle. Although those who have had complete transposition of the great vessels need lifelong follow-up with a cardiologist, arterial switch allows most to go on to lead normal, healthy lives.

All A to Z dictionary entries are regularly reviewed by KidsHealth medical experts.

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