Heart is one of the earliest differentiating and functioning organs which begins to beat when the embryo is about 22-23 days with blood flow beginning in the 4th week. Its development requires coordination of multiple steps that include tube formation, cardiac looping, chamber spetation and development of appropriate inflow and outflow tracts. The coronary artery system and the conduction system also must develop during this period. Once the organs are formed, normal fetal blood circulation has three levels of communication that normally closes after birth. These include ductusvenosus, the foramen ovale and the ductus arteriosus.The ductus arteriosus usually closes 48 hours after birth in 90% of the infants. In premature babies, the ductus arteriosus may not close leading to Patent Ductus Arteriosus requiring surgical intervention. Itconstitutes about 5% to 10% of all congenital heart diseases. In premature infants weighing less than 1750 grams, the incidence is much higher at about 40%. Failure of the closure of ductus results in a left-to-right shunt between the aorta and the pulmonary artery. The magnitude of the shunt depends on the size of the open ductus and pulmonary versus systemic vascular resistance.
Infants with small Patent Ductus Arteriosus are asymptomatic but those with larger Patent Ductus Arteriosus can present with Congestive Heart Failure symptoms.