PATENT DUCTUS ARTERIOSUS (PDA)

Before birth, the blood headed from the heart via the pulmonary artery toward the lungs is shunted into the greatest of arteries (the aorta). The shunt is a short vessel called the ductus arteriosus. When the shunt is open, it is said to be patent (pronounced pa’tent). The patent ductus arteriosus (PDA) usually closes at or shortly after birth permitting blood from that moment on to course freely to the lungs. If the ductus remains open (patent), flow reverses and blood from the aorta is shunted into the pulmonary artery and recirculated through the lungs. The PDA may close later spontaneously (on its own) or need to be ligated (tied off) surgically.