L-transposition of the great arteries is a form of congenital heart disease in which blood circulation flows in the way it should, but serious problems may still exist or develop and require treatment. Read on for information about the characteristics of the defect at birth and the treatment and follow-up care that is necessary into adulthood.

L-Transposition of the Great Arteries in Childhood

L-transposition of the great arteries (L-TGA) is also known as congenitally corrected transposition of the great arteries.This condition is different from D-transposition of the great arteries (d-TGA). In L-TGA, the right and left lower pumping chambers of the heart (ventricles) are switched. The deoxygenated “blue” blood from the right atrium goes to the left ventricle and is pumped to the lungs through the pulmonary artery,  and “red” blood from the left atrium goes to the right ventricle and is pumped to the major artery to the body (the aorta). (Normally, the right ventricle pumps blood to the lungs.) In a baby with L-TGA, “blue” and “red” blood go where they are supposed to, so the arrangement of the heart is “corrected,” even though the pumping chambers are switched.

Symptoms

L-TGA is commonly associated with other heart problems, such as a hole in the wall between the ventricles (ventricular septal defect, or VSD) and an abnormal tricuspid valve connected to the right ventricle (Ebstein’s anomaly). These other problems contribute to the development of heart failure in children and adults with this defect. This defect can also cause problems with irregular heart rhythms, most commonly, complete heart block, which may require a pacemaker. However, if there are no other associated heart problems (VSD or Ebstein’s anomaly), some children can go undiagnosed for many years, even to adulthood.

Progression and Possible Complications

In rare instances where there are no other associated heart defects, patients can live to adulthood without surgery. However, the right and left ventricles are functionally differently so that the usual right ventricle is not equipped to consistently pump against the higher pressure in the arteries of the body. Children with other heart problems may require surgery early in life to help the heart function better. These patients can develop heart failure without surgery.

Treatments

Several options exist if surgery is needed. The VSD can be closed with a patch, but this leaves the “wrong” ventricles connected to their respective great arteries. Ebstein’s anomaly can sometimes be repaired, but may require valve replacement.

Some patients undergo a surgery called a “double switch.” This is two operations performed at the same time. The first part of the operation is an atrial switch. There are two names for this surgery depending on how the surgeon performs it, either a Mustard or a Senning operation. The operation reroutes blood from the right atrium to flow to the right ventricle and blood from the left atrium to flow to the left ventricle.

The second part of this operation is an arterial switch. This involves disconnecting the pulmonary artery and the aorta, switching them and sewing them back to their proper ventricle. In this manner, blood from the right ventricle goes to the pulmonary artery and blood from the left ventricle goes to the aorta. Additionally, the coronary arteries must be reconnected to the vessel that becomes the aorta.

Follow-Up Care into Adulthood

If You Are Diagnosed in Adulthood…

Some patients are diagnosed with L-TGA for the first time in adulthood. These adults typically do not have other associated defects, such as VSD or Ebstein’s anomaly. However, there are other issues that require long-term follow-up with a cardiologist who specializes in congenital heart disease. Heart failure can occur because the right ventricle is not usually equipped to pump blood to the body for several decades. Also, backflow of blood through the tricuspid valve connected to the right ventricle is common and can lead to congestive heart failure. Your cardiologist may prescribe medicines to help alleviate some of these symptoms. Some valves may be damaged so severely that they will require surgery for valve repair or valve replacement.

Heart rhythm abnormalities are also common in patients with L-TGA. The most common of these is complete heart block, which results in slowing of the heart rate. These patients require a pacemaker to treat the abnormal heart rate.

If You Were Treated as a Child and Are Now an Adult…

Adults who underwent surgery as children have many of the same long-term problems as those who are diagnosed in adulthood. The risk of complete heart block is higher in those who have had surgery. Patients who have had only VSD patch closure or Ebstein’s anomaly repair are still using their right ventricle to pump blood to their body. This requires close monitoring for symptoms of congestive heart failure.

Patients who have undergone a “double switch” require follow-up to monitor the area where the blood is rerouted between the two atria to make sure it remains wide open without narrowing. Also, the area in the pulmonary artery and the aorta where the surgeon had to cut the blood vessels to move them to the correct ventricle can become narrowed. Coronary artery problems can also occur when they were reimplanted. Many of these issues can be treated with a balloon catheter or stent.

Lifestyle Considerations

Consult your cardiologist about the kind and level of activity that is appropriate for you, given your condition. Check with him or her before trying new activities.