Transposition of the great vessels

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Heart, front view

Heart, section through the middle

Transposition of the great vessels

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).

Transposition of the great arteries

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.

Review Date: 12/13/2006
Reviewed By: Anne J. L. Chun, M.D., Assistant Professor of Pediatrics, Division of Pediatric Cardiology, New York University School of Medicine, New York, NY. Review provided by VeriMed Healthcare Network.