Transposition of the great vessels is a congenital heart defect in which the 2 major vessels that carry blood away from the heart -- the aorta and the pulmonary artery -- are switched (transposed).

The cause of most congenital heart defects is unknown.

Factors associated with a higher than normal rate of this disease include:

• Rubella or other viral illness in the mother during pregnancy
• Poor nutrition in the mother during pregnancy (prenatal nutrition)
• Alcoholism
• Mother's age over 40
• Diabetes

Transposition of the great vessels is a cyanotic heart defect. This means there is too little 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 goes through the lungs, then to the rest of the body, then back to the lungs again. In transposition of the great vessels, the blood does not travel from the lungs to the body and back to the lungs again. Instead, blood flow in the lungs and blood flow in the body occurs independently. So the blood with oxygen from the lungs does not get to the heart, where it feeds the rest of the body. The blood that goes through the body lacks oxygen.

Symptoms appear at birth or very soon afterwards. How bad the symptoms are depend on the type and size of the heart defect and how much oxygen moves through the body's general blood flow. The condition affects approximately 40 out of 100,000 infants. It is the most common cyanotic heart defect identified in the first week of life.

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

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

Tests often include the following:

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

A medicine called prostaglandin will be immediately given to the baby. The medicine is given to the baby through an IV (intravenous line). This medicine helps blood flow through the lungs and body.

Surgery to temporarily adjust the affected blood vessels may be needed shortly after birth. In most hospitals, a type of surgery called an arterial switch procedure can be used to permanently correct the problem within the first week of life.

Improvement in symptoms and growth and development is seen after surgical correction of the defect. If corrective surgery is not performed, the life expectancy is shortened.

• Arrhythmias
• Heart valve problems
• Coronary artery disease

This condition can be diagnosed before birth using a fetal echocardiogram. If it is 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.

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

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