Definition of Pulmonary atresia:

Pulmonary atresia is a form of congenital heart disease in which the pulmonary valve does not form properly. The pulmonary valve is an opening on the right side of the heart that regulates blood flow from the right ventricle (right side pumping chamber) to the lungs.

In pulmonary atresia, a solid sheet of tissue forms where the valve opening should be, and the valve remains closed. Because of this defect, blood from the right side of the heart cannot go to the lungs to pick up oxygen.

Causes, incidence, and risk factors:

As with most congenital heart diseases, there is no known cause of pulmonary atresia. The condition is associated with another type of congenital heart defect called a patent ductus arteriosus (PDA).

Persons with pulmonary atresia may also have a poorly developed tricuspid valve. They may also have an underdeveloped right ventricle and abnormal blood vessels feeding the heart.

Pulmonary atresia may occur with or without a ventricular septal defect (VSD). If the person does not have a VSD, the condition is called pulmonary atresia with intact ventricular septum (PA/IVS). If the person has both problems, the condition is called pulmonary atresia with VSD. This is an extreme form of tetralogy of Fallot. Although both conditions are called pulmonary atresia, they are actually different defects.