Patent ductus arteriosus (PDA)

One of the heart problems diagnosed in these children was a patent ductus arteriosus. The ductus arteriosus is a blood vessel that is present in all babies before they are born. While in the womb, the lungs of the fetus cannot provide oxygen to the fetus's blood. Instead, the fetus receives its oxygen from its mother, through the umbilical cord. Because of that, the fetal lungs do not need to receive the volume of blood flow that will be required after birth. The ductus arteriosus connects the pulmonary artery to the aorta, allowing blood to bypass the lungs. Normally the ductus arteriosus closes on its own within a few days of birth as the lungs begin to strengthen and provide the body with the oxygen it requires. Once it is closed it is referred to as a ligamentum arteriosus.

Occasionally, the ductus may not close on its own and remains open (or, in medical terms, patent). This condition is called a patent ductus arteriosus (PDA). In some babies, a procedure known as a PDA ligation must be performed to close (or, in medical terms, to ligate) the PDA and prevent blood from flowing through it. Otherwise, if the ductus arteriosus remains patent, the newborn may develop congestive heart failure from the increased pulmonary blood flow.

Sometimes closure of the ductus is not a positive development if the baby suffers from other defects that prevent adequate blood flow to either the lungs or body. Then the patent ductus may provide an alternative and necessary route for blood flow. In these babies, a drug (prostaglandin) can be given to keep the ductus open.

Diagram 2.4 Patent ductus arteriosus 1 - open or patent ductus arteriosus The shunt or abnormal flow is from aorta to pulmonary artery as indicated by the shaded red arrow.