In normal circulation, the aorta leaves the left side of the heart and brings red, oxygenated blood to the organs and tissues of the body. The pulmonary artery leaves the right side of the heart and brings blue, deoxygenated blood to the lungs. Occasionally, a child may be born with extra blood vessels that come off of the aorta and travel to the lungs. These are called aortopulmonary (AP) collaterals. They may be present in the setting of other congenital (existing at birth) heart disease. Sometimes the pulmonary artery fails to develop normally and may be too small to take the blue blood to the lungs. Aortopulmonary collaterals may form so that blood can get to the lungs. In this case these vessels are need so blood can pick up oxygen from the lungs.
Other times these vessels supply blood to a segment of lung that has blood flow from another source (the pulmonary artery). It may be beneficial to occlude (close off) these extra blood vessels if these vessels will not be used during a corrective surgery.
Similarly, small blood vessels may arise from normal arteries, which then allow extra blood to go to the lungs in the presence of long-standing cyanotic (causing bluish-skin) congenital heart disease. Some doctors believe the presence of these vessels may not be helpful because they may allow too much extra blood to enter the lung vessels. The presence of these vessels may prolong the hospital stay after heart operations. These vessels can be occluded using metal coils or small alcohol particles that are placed using a thin, flexible tube called a catheter that is inserted into the blood vessel being treated.