How is this defect treated?
A heart operation will be necessary to correct the defect. While waiting for surgery, a medicine called prostaglandin may be used to keep the ductus arteriosus open and allow for better mixing of red and blue blood. A procedure called a balloon atrial septostomy may be needed to increase mixing of red and blue blood inside the heart and prevent complications of severe cyanosis. This procedure is done during a heart catheterization. A thin plastic tube or catheter is placed into a large vein in the baby's groin. This catheter is then passed into the right atrium and across the small hole in the wall between the right and left atrium. Once the catheter is in the left atrium a balloon is expanded and pulled back through the hole into the right atrium making the hole bigger. This allows more mixing of the red and blue blood and higher oxygen levels while the baby awaits surgery.
The age of the child at operation and the kind of operation will depend on the child's symptoms and the precise anatomy of the defect. The surgery most frequently performed for complete TGA with or without a ventricular septal defect is called an arterial switch operation. In this operation the two blood vessels which are reversed are "switched" back to the correct location. This operation must be done within the first few weeks of the infant's life when both the right and left ventricle are used to pumping blood against the higher pressures found in the fetal circulation.
When a surgeon fixes this defect an incision is made down the center of the breast bone and the heart is stopped for a short period of time while the body is supported with a heart/lung bypass machine. The aorta and pulmonary artery are divided and reconnected so that the pulmonary artery is connected to the right ventricle(1) and supplies blue blood to the lungs. The aorta is connected to the left ventricle and supplies red blood to the body (2). The coronary arteries are also relocated so that they will receive red blood from the aorta for the heart muscle itself. If there are any septal defects, either in the atrium or the ventricle, these holes are also closed.
At the end of the operation the baby's heart is completely normal both in its connections (anatomy) and in the way the blood flows (physiology). In addition, this operation provides the advantage of keeping the left ventricle on the side of the heart that pumps blood to the body.
If the baby is older at the time of diagnosis or there is an unusual location of one of the coronary arteries, the surgeon may choose to perform an atrial switch operation called a Mustard or Senning operation. For this operation, now rarely used, the incision is made as it is with the arterial switch and the heart/lung bypass machine is used. The venous drainage of blood coming into the heart is rerouted rather switching the arteries that carry blood out of the heart. In this case the blue blood returning to the right atrium is redirected to the left atrium (1), flows to the left ventricle (2) where it is pumped through the pulmonary arteries to the lungs. Red blood returning from the lungs is baffled to the right atrium (3), flows to the right ventricle (4) where it is pumped through the aorta and out to the body. Even though the blood goes to the right location, the heart remains configured so the right ventricle pumps blood to the body and the left ventricle pumps blood to the lungs.