Before birth, a human heart has a number of open passages between various chambers and vessels.  These openings prior to birth are needed to supply oxygenated blood to the baby’s body, since the child’s lungs do not function until birth.

The Ductus Arteriosus is an open passageway between two large blood vessels (the pulmonary artery and the aorta). In a normal heart the pulmonary artery carries venous (blue) blood from the heart's right side to the lungs. There it picks up a fresh supply of oxygen and is returned to the left side of the heart. The aorta carries the oxygen-rich (red) blood from the left side of heart to the rest of the body.

In the fetal heart, oxygen is provided by the mother's blood, and the circulation of blood through the lungs is not necessary. An open passageway between the pulmonary artery and the aorta allows the blood to bypass the lungs. The passageway is called a Ductus Arteriosus.

The Ductus Arteriosus normally closes within a few hours after birth. If this opening does not close, blood can pass through, and a Patent (or open) Ductus Arteriosus (PDA) results. For infants with Patent Ductus Arteriosus (PDA), some blood that should go through the aorta to the body goes through this opening, and back to the lungs through the pulmonary artery.

The defect often corrects itself within several months of birth, but in many infants the PDA does not fully close, which can lead to health issues as the child grows and develops.
 
If a large PDA is not corrected, the pressures in the pulmonary arteries may become very high and induce changes in the arteries themselves that can result in further heart abnormalities. In some cases, the pressures in the right side of the heart become high enough that blood may flow from the right to the left side of the heart.

This short circuit of the blood makes the heart work harder to maintain sufficient blood flow to the body. Children with a PDA may tire quickly, breathe rapidly, grow more slowly than normal, and be prone to catch pneumonia and other bacterial infections more easily. Over time, the condition can cause enlargement of the heart from the stress of pumping more blood than normal to maintain circulation. In some children, may begin symptoms shortly after birth. If the Patent Ductus Arteriosus is relatively small, there may not be any symptoms until later in life.

Treating Patent Ductus Arteriosus (PDA)

AGA Medical designed the AMPLATZER® Duct Occluder to allow closure of PDA defects using a minimally-invasive catheter procedure instead of surgery.