Transposition of the great arteries

Transposition of the great arteries is a reversal of the aorta and pulmonary artery, the two major blood vessels leaving from the heart. There are two types of transpositions, a D-type and an L-type.

In D-type transposition of the great arteries (D-TGA), the two main arteries (aorta and pulmonary artery) are connected to the wrong chambers of the heart. When the vessels are switched, the aorta is on the wrong side of the heart and gets oxygen-poor blood from the body instead of oxygen-rich blood fresh from the lungs. The oxygen-poor blood continues to recirculate to the body. At the same time, the pulmonary artery keeps recirculating oxygen-rich blood to the lungs instead of sending it out to the body. This heart defect will require surgery.

In L-type transposition of the great arteries (L-TGA), not only are the two great arteries reversed, but the two ventricles are also in abnormal positions. Oxygen poor blood travels from the right atrium, to the left ventricle, then out to the pulmonary artery and lungs. Oxygen rich blood travels from the left atrium, to the right ventricle then out the aorta to the body. Overall, blood flow is normal and the condition does not require an operation, however there are many heart defects associated with L-TGA that may require intervention. In addition, the conduction system of the heart can be abnormal and the right ventricle has to do the work of the left ventricle which makes it apt to fail over time.

The cardiothoracic surgeons at Norton Children’s Heart Institute — the leading providers of pediatric heart care in Louisville and Southern Indiana — have been repairing D-type transposition of the great vessels with the arterial switch surgery for decades.

The board-certified and fellowship-trained specialists at Norton Children’s Heart Institute, affiliated with the University of Louisville, have the skill and experience to provide a pinpoint diagnosis and develop a customized treatment plan for you and your child.

D- type transposition of the great arteries symptoms

D-type transposition of the great vessels (D-TGA) almost always is diagnosed in the first hours or days of life. Babies born with D-TGA often appear blue — a condition called cyanosis — caused by low oxygen levels in the bloodstream. They may have trouble feeding and breathing.

Babies with D-TGA need a connection between the right and left circulations. This can occur via a patent ductus arteriosus (PDA), an atrial septal defect or patent foramen ovale (PFO), or a ventricular septal defect. These connections may allow enough mixing of the blood to prevent severe cyanosis in the first hours or days of life. A PDA or PFO typically closes within a few days after birth, which can make the cyanosis more severe.

As the child experiences low oxygen levels, rapid breathing occurs. The infants may become more blue or cyanotic in color, not move around as much, and not want to feed.

Transposition of the great arteries diagnosis

Transposition of the great arteries can be diagnosed by an ultrasound test during pregnancy, although it can be missed during a routine fetal ultrasound. A fetal echocardiogram performed by heart specialists may be needed to find a transposition of the great arteries during pregnancy. The echocardiogram will show the child’s heart and allow specialists to diagnose the condition.

Babies with cyanosis often are placed on oxygen. If a baby has an issue with the lungs, the oxygen therapy will improve the baby’s oxygen levels. In cases of a heart issue, oxygen therapy will not improve the child’s oxygen levels. When this happens, it is a sign that the baby may have a heart condition such as transposition of the great arteries. Doctors will then order a echocardiogram (ECHO) at the bedside which will help them diagnose transposition of the great arteries.

If left untreated, over 50 percent of infants with transposition of the great arteries will die in the first month of life. 90 percent will die in the first year.

D-type transposition of the great arteries treatment

When a baby is first suspected of having D-type transposition of the great arteries (D-TGA), the first focus is to help the child maintain safe oxygen levels as well as safe heart and lung function.

After a diagnosis is suspected or confirmed, doctors may:

  • Give a steady dose of prostaglandins, a medicine that helps keep the ductus arteriosus open. This allows oxygen-rich blood to mix with some of the oxygen-poor blood.

Once the diagnosis is confirmed, doctors may:

  • Perform a balloon atrial septostomy. With this procedure, a balloon-tipped catheter is inserted into the heart to stretch or enlarge the foramen ovale, a natural connection that babies have between the right atrium and left atrium. The catheter is placed by threading it through a blood vessel in the navel or groin. Making the foramen ovale bigger creates an atrial septal defect, a hole that allows oxygen-rich blood to mix with oxygen-poor blood. This way, the baby’s oxygen levels can stay in a safe range, often around 80 percent. After a balloon atrial septostomy, the baby can stop receiving prostaglandins. The balloon placement helps keep the baby stable before the D-TGA is corrected with surgery. Corrective surgery usually is performed during the first week of life.
  • Perform an arterial switch. This operation is performed on most cases of D-TGA. Surgeons cut the aorta and pulmonary arteries just above the point where they leave the heart, then reconnect them to the proper ventricles. The valves stay attached to the ventricles, so what was once the pulmonary valve becomes the aortic valve and vice versa. The coronary arteries must be taken off the area above the valve and replanted separately above the new aortic valve. During this surgery, any ventricular septal defects (if present) and atrial septal defects also are repaired. In some cases, an arterial switch may not be the best answer. Your heart team will work with you and your child to decide the best course of treatment.

D-type transposition of the great arteries complications and follow-up after surgery

Before surgeons developed the arterial switch procedure a generation ago, half the babies born with this defect died within a month. Up to 90 percent of babies didn’t live to see their first birthday. Now, some of the first babies to have this surgery to correct transposition of the great vessels are young adults and living full, active lives.

Here is what you can expect after surgery, including complications children may experience.

Since the arterial switch surgery reconstructs the heart to work the way it should, long-term heart function should be excellent. Patients usually have normal ventricular function and no heart rhythm issues, such as murmurs.

However, a small percentage of children can experience:

  • A narrowing (stenosis) where the aorta and pulmonary artery are reattached to the correct ventricles, which can happen months or years after surgery. It may require a repair, including cardiac catheterization with balloon dilation of the narrowed area or another operation, depending on the characteristics of the narrowing.
  • The aorta enlarging where it arises from the left ventricle
  • Issues with flow through the coronary arteries

As a child grows after an arterial switch, they can have good quality of life, including participating in physical activity and sports without difficulty or restrictions. Repeat surgeries usually are not expected, but may be needed in later years if narrowing of the great arteries or enlargement of the aorta occurs.

A child is expected to have long-term follow-up with a cardiologist to watch for any issues as they arise. Follow-up will include regular heart exams, scheduled echocardiograms and perhaps exercise stress tests.

Why Norton Children’s Heart Institute?

Norton Children’s Heart Institute, affiliated with the University of Louisville, is a comprehensive pediatric heart surgery, heart failure and heart transplant program serving Kentucky, Southern Indiana and beyond.

The goal of the full-service Norton Children’s Heart Institute is to provide care for the child and the whole family. Our specialists are prepared to repair even the most complex congenital and acquired heart conditions.

Our heart team includes:

  • Pediatric cardiothoracic surgeons
  • Pediatric transplant surgeons
  • Pediatric cardiologists
    • Fetal cardiologists
    • Adult congenital heart cardiologists
    • Heart failure/heart transplant cardiologists
    • Pediatric electrophysiologists
    • Pediatric cardiac catheterization cardiologists
  • Pediatric cardiovascular anesthesiologists
  • Pediatric intensive care physicians
  • Cardiac critical care nurses
  • Critical care pharmacists
  • Family support team
  • Child life specialists
  • Rehabilitation specialists
  • Social workers
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