Unusual association of isolation of right pulmonary artery in absent pulmonary valve syndrome.

Absence of arterial duct, a sixth aortic arch derivative, plays an important etiologic role in Tetralogy of Fallot with absent pulmonary valve syndrome. When fetal ductus is absent, the large right ventricular stroke volume dilates the pulmonary trunk leading to pulmonary regurgitation. A proximal extension of the embryonic insult to the entire left sixth arch causes absence of the left pulmonary artery, a common association of absent pulmonary valve syndrome. On the contrary, absence of right pulmonary artery is not reported in absent pulmonary valve syndrome. A rare combination of tetralogy, absent pulmonary valve syndrome and isolation of a hypoplastic right pulmonary artery offered challenges to diagnosis and management.