A congenital heart defect in which the position of the two major vessels that carry blood away from the heart, the aorta, and the pulmonary artery, is switched (transposed).
Alternative Names
Transposition of the great arteries
Causes, incidence, and risk factors
The cause of most congenital heart defects is unknown. Prenatal factors that are associated with a higher than normal incidence of the disease include maternal rubella or other viral illnesses during pregnancy , poor prenatal nutrition, maternal alcoholism , maternal age over 40, and diabetes . Transposition of the great vessels is classified as a cyanotic heart defect because the condition results in insufficiently oxygenated blood pumped to the body which leads to cyanosis (a bluish-purple coloration to the skin) and shortness of breath . In transposition of the great vessels, there is no communication between the pulmonary circulation and the systemic circulation. Fresh oxygenated blood from the lungs returns to the heart ready to nourish the body, but instead is whisked right back to the lungs. Conversely, oxygen-poor blood returns from the body to the heart and is then sent right back out to the body without being reoxygenated. There is usually an associated defect that permits the mixing of the systemic and pulmonary circulation to provide some oxygenated blood to the body. Without such a defect, the condition is fatal. Symptoms appear at birth or very soon afterwards. The severity of the symptoms depends upon the type of associated defect and the resulting amount of oxygenated blood supplied to the general circulation. 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.
Treatment
Immediately after diagnosis, a prostaglandin drip is started to maintain the small connections (the ductus arteriosus and the foramen ovale) between the pulmonary and systemic circulations. Palliative surgery may be indicated shortly after birth, with permanent correction postponed until the child is one year old and able to tolerate more extensive surgery. Palliative measures include enlarging or creating a hole in the atrium to allow oxygenated blood into the general circulation. Reconstructive open heart surgery will redirect the blood flow appropriately. A newer surgical technique known as an arterial switch procedure may allow permanent correction within the first month of life.
Expectations (prognosis)
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.
Calling your health care provider
Call your health care provider if symptoms develop, become worse over time, or if symptoms continue after treatment.
Prevention
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 BEFORE and DURING pregnancy may be helpful.