children s health issues
Transposition of the Great Arteries
Introduction
Transposition of the great arteries is a reversal of the normal connections of the aorta and the pulmonary artery with the heart. The aorta and pulmonary artery are reversed, which causes oxygen-poor blood to be circulated to the body and oxygen-rich blood to be circulated between the lungs and the heart and not to the body. Symptoms are apparent at birth and include severe cyanosis (a bluish discoloration of the lips and skin) and difficulty breathing. The diagnosis is based on echocardiography. Medication or urgent cardiac catheterization may be needed shortly after birth. Surgery is done during the first few days of life. (See also Overview of Heart Defects .) Oxygen-poor blood returning from the body enters the right atrium and then flows to the right ventricle as usual, but then flows to the aorta and the body, bypassing the lungs. Oxygen-rich blood travels back and forth between the heart and lungs (from the lungs to the pulmonary vein, then left atrium and ventricle, then the pulmonary artery) but is not transported to the body. The body cannot survive without oxygen. However, infants with this heart defect may survive briefly after birth because the foramen ovale (a hole between the right and left atria) and the ductus arteriosus (a blood vessel connecting the pulmonary artery with the aorta—see Normal Fetal Circulation ) are still open at birth. These openings allow oxygen-rich blood to mix with oxygen-poor blood, usually supplying enough oxygen to the body to keep the infant alive. Once the ductus closes, as it normally does after birth, if the atrial opening is very small, very little oxygen-rich blood is able to get to the body. The infant will die if the atrial defect is not enlarged immediately. Transposition of the great arteries can also be accompanied by another heart defect, Atrial and Ventricular Septal Defects (a hole in the wall separating the two lower heart chambers), which may actually be helpful by allowing more mixing of oxygen-rich and oxygen-poor blood. The normal connections of the aorta and the pulmonary artery with the heart are reversed. 