Levo-Transposition of the Great Arteries (L-TGA) is a congenital heart defect where the connections between the atria and ventricles, and ventricles and arteries are abnormal.

Though abnormal, the blood flow patterns are essentially normal in L-TGA. The “blue”, oxygen-deficient blood goes to the lungs and the “red”, oxygen-rich blood goes to the body.

The problem is that the ventricles are not in the correct positions. This means the right ventricle is doing the work normally done by the left ventricle – pumping blood to the body. It is a harder job to pump blood to the body. The pressures in the body are higher than the pressures in the lungs.

Most of the time, the right ventricle finds a way to keep up with this job, but sometimes it reaches a point where it is not strong enough to do its job. At that time, patients will start to develop signs of heart failure. They may have difficulty breathing, tire more easily and have difficulty exercising.

It is difficult to predict how long the right ventricle will be able to handle its job. Some people develop problems as infants, while others are healthy well into adulthood.

Since the blood gets to the correct place, some people call this “congenitally corrected.”

Many patients with L-TGA will also have other heart abnormalities. This includes holes in the heart, like ventricular septal defects (VSDs) and atrial septal defects (ASDs). There can also be valve abnormalities. These other abnormalities can affect the blood flow patterns.

L-TGA Cause and Diagnosis

In most cases, there is no known cause for L-TGA and there are no specific genetic syndromes seen with L-TGA.

TGA is usually diagnosed with an echocardiogram, an ultrasound of the heart.

Some may be diagnosed by a fetal echocardiogram before birth, but others may not be detected until after birth.

Some people do not get diagnosed until they are much older. This is usually the case when there are no other heart problems with the L-TGA. The diagnosis would be confirmed with an echocardiogram.

L-TGA Symptoms

Patients with L-TGA can have a variety of symptoms, including:

  • Difficulty breathing
  • Tiring more easily
  • Difficult exercising

Many patients with L-TGA have other heart abnormalities. Some of these may contribute to the symptoms that patients have. Holes in the heart may lead to earlier signs of heart failure, as can valve abnormalities. Some patients may have mild symptoms, while others may be more severe.

Patients with L-TGA can have heart rhythm problems. They are at higher risk to have fast abnormal heart rhythms. They are also at risk to develop heart block, which is when the electrical activity does not travel normally from the atria to the ventricles.

Treatment Plan for L-TGA

If the diagnosis of L-TGA is discovered before birth, then your baby’s delivery may be planned. He or she will go to the neonatal intensive care unit (NICU) after birth for close monitoring.

The same things would happen if the diagnosis is made after birth. If the baby has no other problems and is not expected to have any symptoms right away, he or she can go home soon after birth with frequent monitoring as an outpatient.

Many children are diagnosed later in life. Their care will depend on their symptoms and on the other heart problems. At the very least, they will have an echocardiogram and electrocardiogram.

Surgery for L-TGA

View our pediatric cardiac surgery outcomes.

Patients who have only L-TGA with no other major heart problems, no symptoms and normal function of the right ventricle may not require heart surgery. They will need to be closely monitored for any changes.

Some patients may have surgery to close holes in the heart (ASDs or VSDs) or to repair valves.

Sometimes a more complicated surgery is done to relieve the right ventricle and make the left ventricle the pump to the body. This surgery is called a double switch operation, involving rerouting the blood return from the body and lungs, and also switching the route of the arteries. This makes it so the blood flows to the correct places and the left ventricle is back to doing the job of pumping to the body.

The timing of the double switch operation is important. If the left ventricle does not pump at high pressures for a long time its muscle will get weaker.

In young patients, the muscle may need to be retrained to make it strong enough to act as the pump to the body. This retraining may require surgeries before the double switch to make the left ventricle stronger. If the left ventricle goes too long without pumping at high pressure, it could be unable to be retrained and the double switch may not be possible.

Some patients with L-TGA may require repeat procedures or surgeries, and some who have poor function of the right ventricle may eventually need a heart transplant.

All patients will need lifelong follow up with a cardiologist.

Long-term Prognosis - L-TGA

In general, the long-term prognosis for L-TGA is good, although it depends on how well the right ventricle functions.

Although patients may need additional surgeries or procedures, they are not typically on a lot of medications. Their activities are typically not limited. Some patients may develop heart rhythm abnormalities later in life, requiring medications or pacemakers.

When one family member has a congenital heart defect, there is an increased risk in other family members. A genetic counselor can better determine what the risk would be for future pregnancies.

To make an appointment with a Children's Heart Program physician, please call 410-328-4348.

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