Transposition of the Great Arteries (TGA)

What is transposition of the great arteries?

In transposition of the great arteries (TGA), the “great” arteries, the aorta and the right ventricle, are reversed in their origins from the heart. The aorta is connected to the right ventricle and the pulmonary artery is connected to the left ventricle — exactly the opposite of a normal heart’s anatomy. TGA is a universal term that may
also be referred to as dextro-Transposition of the great arteries (d-TGA) and levo-transposition of the great arteries (l-TGA), otherwise known as congenitally corrected transposition of the greater arteries. 

With these arteries reversed, oxygen-poor (blue) blood returns to the right atrium from the body, passes into the right ventricle, then goes into the aorta and back to the body. Oxygen-rich (red) blood returns to the left atrium from the lungs and passes into the left ventricle, which pumps it back to the lungs — the opposite of the way blood normally circulates.

illustration of a normal heart and a heart with transposition of the great arteries (TGA)

Most babies with TGA are born with a small hole between their atria, which allows just enough red blood to get to the body to maintain life for a few hours. Typically diagnosed within the first hours after birth, TGA is life threatening, and in order to survive babies need special therapy urgently.

The most commonly used initial therapy is balloon atrial septostomy, where a balloon at the end of a catheter (small, flexible tube) is used to enlarge the opening between the atria. Complete open-heart repair generally takes place a few days later.

If there are no unusual risk factors, more than 98 percent of surgically-treated infants survive their infancy. Most children who’ve had TGA surgery recover and grow normally, although they can be at some risk in the future for arrhythmias, leaky valves and other heart issues.

What are other defects associated with transposition of the great arteries?

Most babies with TGA have only that defect, but there are other defects that can occur with TGA:

Atrial septal defect (ASD)

ASD is an opening between the right and left atria. This defect occurs occasionally with TGA and is actually helpful; it easily can be corrected at the time of surgery.

Ventricular septal defect (VSD)

VSD is an opening in the wall of tissue (ventricular septum) separating the right and left ventricles. This occurs in about 25 percent of patients with TGA. If large enough, a VSD will need to be surgically closed at the time of surgical correction.

Patent ductus arteriosus (PDA)

The ductus arteriosus is a blood vessel that’s normally open (patent) while the baby is inside the mother, but which closes naturally shortly after birth. Because keeping this vessel open helps increase the blood oxygen level in babies with TGA, doctors often give patients a medicine (prostaglandin E1) to keep the ductus open.

How we care for transposition of the great arteries

At Boston Children’s Hospital, our team of experts in the Department of Cardiac Surgery has many decades of experience helping children who have been diagnosed with transposition of the great arteries.