complete blockage between the heart and the pulmonary artery- the main lung artery.

Absence of the normal opening from the right ventricle into the pulmonary artery.

An imperforate pulmonary valve. When associated with a VSD (variant of tetralogy of Fallot), pulmonary blood flow arises from aorto-pulmonary collaterals, and systemic venous return exits the right heart via the VSD. When associated with intact interventricular septum, pulmonary artery blood supply is via a patent ductus arteriosus, and systemic venous return exits the right heart via an obligatory ASD.

blood cannot be pumped to the lungs from the right ventricle through the pulmonary artery, which is blocked or missing

Absence of the pulmonary valve.

A heart defect where the vessel leaving the heart to go to the lungs (Pulmonary Artery) is too small to channel blood effectively. For more information see the Factsheet on Pulmonary Atresia.

Pulmonary atresia is a congenital malformation of the pulmonary valve in which the valve orifice fails to develop. The valve is completely closed thereby obstructing the outflow of blood from the heart to the lungs.