**6.4 Patent ductus arteriosus (PDA)**

Ductus arteriosus is a normal communication in fetus, which constrict and closes within 10- 15 hrs of birth and later closed anatomically by fibrosis in 2 – 3 weeks. Various mechanism have been described for initial functional closure, which includes increased PaO2, absence of placental derived prostaglandins and presence of catecholamines and bradykinins in new born.

Ductus venosus provides a communication between junction of main and left pulmonary artery and lesser curvature of descending aorta after left subclavian artery origin. Higher incidence of patent ductus arteriosus is seen in premature, females, children living at high altitude and associated with maternal rubella.

It provides left to right shunt causing high pulmonary flow and volume load on left atrium and ventricle. Pulmonary congestion and recurrent infection is commonly seen if remain open.

Medical management includes three doses of indomethacin. If medical management fails then either transcatheter or surgical closure becomes necessary. Surgical techniques include ligation via left thoracotmyn sternotomy or recently by video assisted thoracoscopy.
