Transposition of the Great Vessels

In the normal heart, their are two "great vessels": the aorta which carries blood from the left ventricle to the body and the pulmonary artery which carries blood from the right ventricle to the lungs. In transposition, these two great vessels are switched (transposed) with the aorta arising from the right ventricle, and pulmonary artery arising from the left ventricle. This results in two separate circulations:

1) "Red blood" pumped continually through the left side of the heart to the lungs and back, without entering the rest of the body.

2) "Blue blood" pumped continually through the right side of the heart to the body and back, without entering the lungs.

Babies born with transposition are cyanotic (bluish color of skin, lips, and nail beds) shortly after birth because of the low oxygen in their blood. Two normal connections in the newborn heart and blood vessels help some "red blood" and "blue blood" to mix, keeping babies alive. One connection, the foramen ovale, is an opening between the two atria (upper chambers). In some patients, if the foramen ovale is not open enough for blood to mix, a balloon can be passed through this opening, making it larger. In addition, medicine can be given to keep the second connection (called a patent ductus arteriosus) open. This second connection is a blood vessel between the aorta and pulmonary artery, which usually closes after the first few days of life.

Ultimately, surgery is required in order for enough red blood to circulate through the body. The type of surgery performed depends upon a number of factors including the age of the child, the child's general state of health and the exact nature of the heart defect.

Children with transposition require penicillin (also called SBE prophylaxis) prior to any dental work or surgery on the mouth, bowel, or bladder. This helps prevent the uncommon, but possible, occurrence of bacterial infection affecting the heart near the defect or valves.