Absent pulmonary artery. A hint to its embryogenesis.

Cardiac catheterization was performed in nine patients with unilateral absence of a pulmonary artery. Aortography revealed a diverticulum of the innominate artery in five of six patients in whom the aortic arch and absent pulmonary artery were on opposite sides. It is suggested that the diverticulum indicates fetal systemic blood supply to the affected lung through the distal part of the sixth aortic arch, which--consisting of ductal tissue--obliterated after birth, leaving the diverticulum where the ductus joins the innominate artery.