Transposition of the Great Arteries

The Fetal Heart Program at the SSM Health Cardinal Glennon St. Louis Fetal Care Institute brings together the best cardiothoracic surgery, cardiology, neonatology and maternal-fetal medicine experts in the region to care for mothers and their babies who have a congenital heart defect. Advances in technology and treatment options at SSM Health allow us to provide the highest quality care for your little one.

What Is Transposition of the Great Arteries?


Transposition of the great arteries (TGA) is a congenital heart defect where the aorta and pulmonary artery are switched. This changes the way blood circulates through the body causing oxygen-poor blood to flow to the body.

If your doctor suspects a fetal heart anomaly after reviewing your routine ultrasound, he or she may request a fetal echocardiogram (echo), an ultrasound of the fetus’s heart. This safe, noninvasive test shows the structure of the heart and how it is functioning, which can help us confirm the diagnosis of TGA and discuss possible options for treatment after delivery. Our fetal heart team will monitor the baby closely for the remainder of the pregnancy.

How Does TGA Affect Delivery?

Most babies with TGA can be delivered vaginally at full term unless otherwise indicated by your obstetrician. It is best for these babies to be delivered at a medical center where there is access to a team of pediatric cardiologists and neonatologists, along with an established Neonatal Intensive Care Unit (NICU).

After delivery, the baby will need prostaglandin (PGE), an intravenous medication that keeps the patent ductus arteriosus (a normal connection present in babies in the womb) open. The patent ductus arteriosus (PDA) will allow some mixing of oxygenated and unoxygenated blood.

How is TGA Treated?

Medical treatment with PGE is required for all babies with TGA.

At birth, every baby has a patent foramen ovale (PFO), a small hole between the top chambers of the heart (the right and left atria). In TGA, the PFO is very important to allow mixing of oxygenated and unoxygenated blood. If the PFO is not big enough, a cardiac catheterization may be required to perform a balloon atrial septostomy in the first few days of life. This x-ray guided procedure is typically done by placing a thin flexible tube, or catheter, through the umbilical vein (a vessel in the umbilical cord) and does not require an incision. A balloon atrial septostomy creates a larger hole between the top chambers of the heart. The procedure is performed in the pediatric hybrid cardiac catheterization suite at SSM Health Cardinal Glennon Children's Hospital.

The surgical approach for TGA depends on the baby’s anatomy. The most common procedure is the arterial switch. In this open-heart surgery, the pulmonary artery and aorta are switched back to their normal positions.

With early diagnosis and treatment, many children born with TGA live healthy and normal lives. In some cases children may develop narrowing of the pulmonary arteries, which might require further treatment, typically done by cardiac catheterization.

We are here to help – and we’re available 24 hours a day. Call us anytime to schedule an appointment, second opinion, or even if you have a question at (314) 268-4037. Our health care team at the Cardinal Glennon Fetal Care Institute strives to provide the best care possible for your child, allowing you to rest assured your little one’s heart is in good hands.

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