What is transposition of the great arteries (TGA)?

Transposition of the great arteries (TGA) is a complex congenital heart defect. In a normal heart, there are two large arteries that carry blood out of the heart. In children with TGA, these arteries are connected to the heart abnormally:

• The aorta is attached to the right-sided pumping chamber (ventricle), instead of the left.
• The pulmonary artery is attached to the left-sided pumping chamber (ventricle), instead of the right.

Learn more about TGA from the experts at Children's Hospital of Philadelphia's Cardiac Center and Fetal Heart Program in this video series.

Signs and symptoms of transposition of the great arteries

The symptoms of TGA include:

• Blue or purple tint to lips, skin and nails (cyanosis)
• Rapid breathing
• Difficulty feeding, poor appetite and poor weight gain

Testing and diagnosis of TGA

Transposition of the great arteries may be diagnosed before birth, with fetal echocardiogram (ultrasound). Our Fetal Heart Program will prepare a plan for delivery and care immediately after birth.

Sometimes TGA is diagnosed when an infant is a few hours or days old. Less commonly, infants may not have visible symptoms for weeks or months. Pediatricians from other hospitals refer newborns to the Cardiac Center when they notice symptoms or abnormal values on laboratory testing such as pulse oximetry.

Diagnosis of TGA may require some or all of these tests:

• Echocardiogram (also called "echo" or ultrasound): sound waves create an image of the heart
• Electrocardiogram (ECG): a record of the electrical activity of the heart
• Chest X-ray
• Pulse oximetry: a noninvasive way to monitor the oxygen content of the blood
• Cardiac catheterization: a thin tube is inserted into the heart through a vein and/or artery in either the leg or through the umbilicus ("belly button")
• Cardiac MRI: a three-dimensional image shows the heart's abnormalities

Treatment for transposition of the great arteries

Approximately one-third of newborns with TGA have extremely low oxygen levels that can harm their bodies and will require an urgent intervention. This procedure, called a balloon atrial septostomy (BAS), will take place within hours after birth. This life-saving procedure, which creates or enlarges a hole between the upper chambers of the heart to allow red and blue blood to mix, was developed at Children’s Hospital of Philadelphia in the 1960s.

For babies requiring a BAS procedure, the clock begins ticking at the moment of birth and access to immediate expert care is essential. At Children's Hospital, we may recommend that these babies be delivered in our Garbose Family Special Delivery Unit, which is just steps away from our cardiac operative and catheterization facilities.

All children with transposition of the great arteries will require open heart surgery to treat the defect. Without surgical repair, the overwhelming majority of patients with TGA will not survive their first year. The surgery, known as the arterial switch operation, is typically performed within a few days of birth. Surgeons reconstruct the heart so that the aorta is attached to the left ventricle and the pulmonary artery is attached to the right ventricle.

After surgery your child will recover in our Evelyn and Daniel M. Tabas Cardiac Intensive Care Unit (CICU), where he will receive round-the-clock attention from a team of dedicated cardiac critical care medicine specialists.

Outlook for TGA

Until approximately 25 years ago, infants with transposition of the great arteries were managed by alternative surgical procedures, sometimes referred to as the "Senning" or "Mustard" operations. As a result, we don't yet know the truly long-term effects of the arterial switch operation beyond young adulthood. It is anticipated that the overwhelming majority of children born with TGA will go on to lead healthy, productive lives.

Significant limitations of day-to-day activities, including sports, are uncommon. However, prudent physical activity after complex congenital heart surgery is recommended and is best individualized with your child's cardiologist.

Follow-up care for TGA

Through age 18

Children who have had surgical repair of TGA require lifelong care by a cardiologist. The cardiologist may ask for heart tests, including ECGs, echocardiograms, cardiac MRIs and exercise stress tests. The cardiologist may also evaluate your child’s cholesterol level, especially if there is a family history of adult acquired heart disease.

The cardiologist will look for any narrowing where the blood vessels were sewn together. Mild vessel narrowing is usually well tolerated, but more severe narrowing may require intervention. Evaluation of long-term heart muscle function and valve function is also very important. In particular, the former pulmonary valve and surrounding tissue that now functions as the new aortic (or “neo-aortic”) valve and root on the left side of the heart can stretch over time leading to valve leakage. As with all complex congenital heart conditions, additional surgeries may be required as the child grows. Ongoing medication use is uncommon.

Our pediatric cardiologists follow patients until they are young adults, coordinating care with the primary care physicians.

Into adulthood

We will help your child transition to an adult cardiologist. The Philadelphia Adult Congenital Heart Center, a joint program of Children's Hospital of Philadelphia and Penn Medicine, meets the unique needs of adults who were born with heart defects.