Pulmonary atresia with ventricular septal defect (PA-VSD) is a rare cyanotic congenital heart malformation characterized by underdevelopment of the right ventricular outflow tract and atresia of the pulmonary valve, ventricular septal defect (VSD) and pulmonary collateral vessels. Clinical features depend on the anatomic variability of the lesion and patients may be minimally symptomatic, severely cyanotic or may develop congestive heart failure. PA-VSD may represent a severe form of Tetralogy of Fallot (see this term).

In utero, the ductus arteriosus (DA) serves to divert ventricular output away from the lungs and toward the placenta by connecting the main pulmonary artery to the descending aorta. A patent ductus arteriosus (PDA) in the first 3 days of life is a physiologic shunt in healthy term and preterm newborn infants, and normally is substantially closed within about 24 hours after bith and completely closed after about three weeks. Failure of physiologcal closure is referred to a persistent or patent ductus arteriosus (PDA). Depending on the degree of left-to-right shunting, PDA can have clinical consequences.