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Transposition of the great vessels

Definition

Transposition of the great vessels is a congenital heart defect in which the two major vessels that carry blood away from the heart -- the aorta and the pulmonary artery -- are switched (transposed).

Alternative Names

Transposition of the great arteries; TGA; d-TGA

Causes, incidence, and risk factors

The cause of most congenital heart defects is unknown.

Factors in the mother that may increase the risk of this condition include:

• Age over 40
• Alcoholism
• Diabetes
• Poor nutrition during pregnancy (prenatal nutrition)
• Rubella or other viral illness during pregnancy

Transposition of the great vessels is a cyanotic heart defect. This means there is decreased oxygen in the blood that is pumped from the heart to the rest of the body. Low blood oxygen leads to cyanosis (a bluish-purple color to the skin) and shortness of breath.

In normal hearts, blood that returns from the body goes through the right side of the heart and pulmonary artery to the lungs to get oxygen. The blood then comes back to the left side of the heart and travels out the aorta to the body.

In transposition of the great vessels, the blood goes to the lungs, picks up oxygen, and then goes right back to the lungs without ever going to the body. Blood from the body returns to the heart and goes back to the body without ever picking up oxygen in the lungs.

Symptoms appear at birth or very soon afterward. How bad the symptoms are depends on the type and size of heart defects (such as atrial septal defect or patent ductus arteriosus) and how much oxygen moves through the body's general blood flow.

The condition is the second most common cyanotic heart defect.

Symptoms

• Blueness of the skin
• Clubbing of the fingers or toes
• Poor feeding
• Shortness of breath

Signs and tests

The health care provider may detect a heart murmur while listening to the chest with a stethoscope. The baby's mouth and skin will be a blue color.

Tests often include the following:

• Cardiac catheterization
• Chest x-ray
• ECG
• Echocardiogram (if done before birth, it is called a fetal echocardiogram)
• Pulse oximetry (to check blood oxygen level)

Treatment

The baby will immediately receive a medicine called prostaglandin through an IV (intravenous line). This medicine helps keep the ductus arteriosus open, allowing some mixing of the two blood circulations.

A procedure using cardiac catheterization (balloon atrial septostomy) may be needed to create a large hole in the atrial septum to allow blood to mix.

A surgery called an arterial switch procedure is used to permanently correct the problem within the baby's first week of life. This surgery switches the great arteries back to the normal position and keeps the coronary arteries attached to the aorta.

Support Groups

Expectations (prognosis)

The child's symptoms will improve after surgery to correct the defect. Most infants who undergo arterial switch do not have symptoms after surgery and live normal lives. If corrective surgery is not performed, the life expectancy is months.

Complications

• Arrhythmias
• Coronary artery problems
• Heart valve problems

Calling your health care provider

This condition can be diagnosed before birth using a fetal echocardiogram. If not, it is usually diagnosed soon after a baby is born.

Go to the emergency room or call the local emergency number (such as 911) if your baby's skin develops a bluish color, especially in the face or trunk.

Call your health care provider if your baby has this condition and new symptoms develop, get worse, or continue after treatment.

Prevention

Women who plan to become pregnant should be immunized against rubella if they are not already immune. Eating well, avoiding alcohol, and controlling diabetes both before and during pregnancy may be helpful.

References

Zipes DP, Libby P, Bonow RO, Braunwald E, eds. Braunwald's Heart Disease: A Textbook of Cardiovascular Medicine, 8th ed. St. Louis, Mo; WB Saunders; 2007.