D-Transposition of the Great Arteries

Overview

D-transposition of the great arteries (D-TGA), a form of congenital heart disease (CHD) that must be corrected shortly after birth for survival, results when the aorta and pulmonary artery are switched. Usually, the aorta carries blood from the heart’s lower left chamber (left ventricle) to the body, and the pulmonary artery carries blood from the heart’s lower right chamber (right ventricle) to the lungs. But in the transposition of these two great arteries, the aorta emerges from the right ventricle, sending oxygen-poor blood that has just returned from the body back out to the body without its usual course through the lungs to pick up oxygen. And the pulmonary artery emerges from the left ventricle and sends oxygen-rich blood that has just returned to the heart from the lungs back to the lungs.

Because the blood carried by the aorta to the body does not first go to the lungs to pick up oxygen, it continues to be poorly oxygenated. As a result, the newborn with this heart defect will have intense bluish skin discoloration (cyanosis).

According to the Centers for Disease Control and Prevention (CDC), 1 in 3,413 babies born in the U.S. each year are born with D-TGA.¹ 

Progression and possible complications

Life can’t be sustained unless openings between the left and the right sides of the heart allow blood to mix so that oxygen in the blood going to the body is increased.

Before birth, there are normally two openings between the heart’s left and right sides: the atrial septal defect (a hole between the heart’s two upper chambers) and the ductus arteriosus (a vessel connecting the pulmonary artery and the aorta). These openings typically close soon after birth. When they close, the baby with D-TGA lacks oxygen and becomes quite blue unless steps are taken to increase blood mixing. Without surgical correction, a child with this defect suffers from a lack of oxygen and heart failure and doesn’t live long.

References

1. Centers for Disease Control and Prevention (CDC)