Guide to Transposition of the Great Arteries

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Transposition of the great arteries (TGA) is a rare and complex congenital heart defect in which the two main arteries that carry blood from the heart are switched (transposed). This prevents oxygen-rich blood from being pumped to the rest of the body. Infants born with this condition must receive corrective surgery immediately after birth.

Key Facts

The two main arteries that carry blood from the heart are the pulmonary artery, which transports oxygen-poor blood to the lungs, and the aorta, which transports oxygen-rich blood to the rest of the body. For babies with TGA, these arteries are switched, causing oxygen-poor blood to flow out to the body and oxygen-rich blood to flow back to the lungs.
TGA can be diagnosed during pregnancy or shortly after birth, depending on the severity of the condition and the presence of other heart defects.
Surgical treatment is typically required immediately to widen or create openings to allow oxygen-rich blood to travel to the rest of the body. After treatment, follow-up care will usually be needed to prevent further complications.

Causes

TGA is a congenital condition, meaning that it is present at birth. While the exact reasons TGA forms is still unknown, it is most likely caused by a combination of genetic and environmental factors, including:

Smoking while pregnant
Drinking alcohol while pregnant
Contracting a viral illness while pregnant
Gestational diabetes
Family history of congenital heart disease

Symptoms

Complete transposition of the great arteries, or dextro-transposition of the great arteries (D-TGA), is the most common type of TGA, in which the pulmonary artery and aorta are switched entirely in position. This means that not enough oxygen is being delivered to the rest of the body, resulting in a number symptoms, including:

Blue skin, lips, or fingernails (cyanosis)
Rapid breathing
Difficulty feeding
Poor appetite
Poor weight gain

For D-TGA, surgery is the only treatment for survival.

There is another, rarer type of TGA: levo-transposition of the great arteries (L-TGA), also known as congenitally corrected transposition of the great arteries (CC-TGA). In L-TGA, the heart’s lower chambers are switched, rather than the great arteries directly. Blood oxygenation is not as greatly affected and symptoms may be present but less severe. Infants with L-TGA may go longer without needing corrective heart surgery.

Diagnosis

TGA can be diagnosed either during pregnancy or shortly after birth. During pregnancy, a diagnosis may be made in two ways:

Ultrasound: This test uses sound waves to create a picture of the fetus in the womb. A routine part of pregnancy exams, it is typically the first way TGA is detected.
Fetal echocardiogram: This test provides more detailed images of the fetus’s heart. It can show doctors whether there are defects in the heart’s structure.

After birth, if the baby is showing any signs of TGA, such as blue skin, lips, or fingernails or rapid breathing, a diagnosis may be made using a number of methods:

Chest X-ray: This test creates a detailed picture of the heart and lungs, allowing doctors to check for signs of defects.
Echocardiogram: This technique uses sound waves to produce an image of the heart. Doctors can use it to check the position of the aorta and pulmonary artery, as well as see the heart beating and pumping blood while they check for other defects.
Electrocardiogram: This test measures the electrical activity of the heart. Sensors called electrodes are attached to the patient’s arms, legs, and chest to measure how well the heart is beating.
Pulse oximetry: This simple, noninvasive test measures oxygen levels in the blood. A small sensor is placed on the fingertip to track how well light waves are absorbed. This information is then used to determine how much oxygen is present.

Treatment

There are several surgical procedures that can be used to treat TGA:

Balloon atrial septostomy: This procedure involves inserting a long, thin tube called a catheter into a blood vessel (usually through the groin) and guiding it up into the heart. Once it reaches the foramen ovale—a narrow hole between the left and right atria that all babies have at birth—a balloon at the end of the catheter is inflated, widening the hole to allow the oxygen-rich blood to cross over and mix into the oxygen-poor blood, ensuring more oxygen gets circulated out to the rest of the body. This is used as a temporary measure until a more permanent treatment can be applied.
Arterial switch operation: This procedure restores normal blood flow in the heart by surgically removing the pulmonary artery and aorta and then reattaching them in their correct positions: the pulmonary artery to the right ventricle, and the aorta to the left ventricle. The coronary arteries (small arteries that provide blood to the heart muscle) also must be moved and reattached to the aorta. This operation is the most common way to treat TGA.
Atrial switch operation: This technique leaves the pulmonary artery and aorta in place and instead involves creating a tunnel (baffle) between the left and right atria. This lets oxygen-poor blood move from the right atrium to the left ventricle, through the pulmonary artery, and out to the lungs, where it receives oxygen. When the now oxygen-rich blood returns to the heart, it can pass through the tunnel from the left atrium to the right ventricle, then through the aorta, and out to the rest of the body. However, because this procedure requires the right ventricle to pump blood to the rest of the body instead of just the lungs, it can lead to long-term complications, such as reduced pumping function, irregular heartbeats, and heart failure.
Rastelli procedure: This method is used to treat patients who have both D-TGA and a ventricular septal defect, an opening in the wall between the heart’s two lower chambers, known as the right and left ventricles. A synthetic patch is placed over the ventricular septal defect. This patch also acts as a tunnel (baffle), redirecting oxygen-rich blood from the left ventricle to the aorta. The pulmonary artery is then disconnected from the left ventricle and reconnected to the right ventricle using an artificial valve, allowing oxygen-poor blood to travel to the lungs.
Double switch procedure: This highly complex procedure is used to correct L-TGA by combining the atrial switch and the arterial switch techniques. This redirects blood moving through the heart into the correct chambers and out through the correct arteries (the pulmonary artery and aorta).

After surgery, ongoing monitoring and medications may be needed to manage additional complications, such as high blood pressure, irregular heartbeats, and extra fluid. If the heart is beating too slow, a pacemaker may have to be installed.

Outlook

The long-term outlook for TGA is generally excellent. With proper treatment, most patients are able to gain normal heart function and lead healthy, active lives. In one study of long-term outcomes for patients who have undergone arterial switch operations, the most common treatment for TGA, the 25-year survival rate was 95%.

However, children who receive surgical repair for TGA will require lifelong care and supervision by a cardiologist. Regular follow-ups may include imaging tests to check for any possible defects or complications of the heart as well as exercise stress tests to determine how well the heart is functioning. In particular, doctors will look for excessive narrowing (coarctation) where blood vessels have been sewn together and valve defects, such as leakage. Additional surgeries may be required as the child grows.

Next Steps

If your child has a congenital heart issue such as TGA, the Congenital Heart Center can help. Our team can offer personalized treatment plans delivered with a level of quality that could only come from one of the most experienced programs in the country.

Call us at 212-305-2688 or use our online form to schedule an appointment.