Transposition of the Great Vessels (TGA)

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This is a reversing of the aorta and the pulmonary artery. The aorta arises from the right ventricle and the pulmonary artery arises from the left ventricle resulting in two separate circulations.

• Oxygenated blood is pumped continually through the left side of the heart to the lungs and back, without entering the rest of the body.
• Unoxygenated blood is pumped continually through the right side of the body and back, without ever entering the lungs.

These babies are born quite blue with low oxygen saturation.  The infant is maintained on a medication, prostaglandin (PGE1), intravenously from birth to allow mixing of blue and red blood until surgery.  Additionally there is usually an atrial septal defect or ASD (opening between the upper two chambers) that allows mixing between the two circulations and the baby to have acceptable oxygen saturation. Sometimes a balloon atrial septostomy (Rashkind balloon septostomy) is needed to allow better oxygen saturation prior to the baby going for surgery.

Surgical Correction:  Consists of an arterial switch procedure in which the aorta and pulmonary artery are “switched” so the aorta comes off the left ventricle and the pulmonary artery comes off the right ventricle.  During this procedure, the coronary arteries (small arteries supplying blood to the heart itself) also have to be “switched” and is one of the critical factors in the operation.  Additionally, the PDA and ASD are also closed at the time of the arterial switch procedure.  If there are additional defects such as a coarctation or VSD, they are also corrected at the same time.