In a patient with a deformity in the aortic arch, it is necessary to operate to ensure that the flow of blood to the body is adequate and uninterrupted. In order to provide the baby's brain with blood during this operation, the technique mentioned earlier called selective cerebral perfusion is used. In order to understand how selective cerebral perfusion works, it is important to know that the patient will be placed on cardiopulmonary bypass during surgery. During cardiopulmonary bypass, a machine is used to pump blood to the body. This allows the surgeon to work on the heart and surrounding arteries while still providing blood flow of he brain and body. In the past, when surgery involved correction of abnormalities of the aortic arch, cardiopulmonary bypass would have to be stopped and the arch drained of blood, meaning there would be periods of time where the baby's brain would not receive any blood flow. With selective cerebral perfusion, a small Gore-Tex shunt is attached to one of the blood vessels that branch off of the aortic arch. Blood from the cardiopulmonary bypass machine is them pumped into the shunt where it enters the artery that branches off of the aorta and eventually travels up the neck and into the brain. Other studies have shown that pumping blood into this vessel allows the front portion of the brain to receive blood while the aortic arch abnormality is being corrected. These studies have shown this by using two stickers with special sensors on them that are connected to a monitor. These stickers, when placed on the baby's forehead, show on the monitor whether or not the front part of the brain is receiving blood.