Purpose or Case Report: The rare entity of an absent pulmonary artery has appeared in the literature since 1868, with most cases associated with congenital heart disease of various types. It has also long been observed that the absent pulmonary artery is contralateral to the aortic arch in almost every case. Isolated absence of a single pulmonary artery without associated congenital heart disease is less common, and these patients may present at any time from prenatal screening, neonatal period, early childhood, or even adolescence and adulthood. We will discuss the embryologic origins, clinical presentations, expected imaging findings, and treatment options based on patient ages from newborn to adolescence.

In neonates with an isolated absent pulmonary artery, a patent ductus arteriosus will allow for continued systemic blood supply. Even early on, narrowing of the PDA may be seen as involution is inevitable without intervention. The lung parenchyma is typically preserved, without yet evidence of hypoplasia or oligemia. Once the PDA has closed, robust collateral formation will occur. As patients age without repair, the lung parenchyma may become hypoplastic with diminished lung volumes and vascular markings. Findings suggestive of recurrent infection such as bronchiectasis may also be evident.

Early discovery and treatment is ideal as this will allow for prevention of long term sequelae and the greatest restoration of lung function as the options for repair are limited in the older patient. There is no universal standard approach for repairing the underlying mechanism of providing blood flow to the intrapulmonary pulmonary artery. Early intervention in neonates included PDA stenting or anastomosing the main pulmonary artery with the intrapulmonary pulmonary artery using a synthetic graft. Patients that present after the neonatal period are not likely to be eligible for surgical repair. The most common long term effect of an absent pulmonary artery is pulmonary hypertension, seen in 40% of patients.

The entity of isolated unilateral absence of a pulmonary artery is rare, however demonstrates typical cardiothoracic findings depending on age at presentation. Understanding of embryology, specifically the 4th and 6th primitive aortic arches, allows one to understand why this malformation occurred and what findings to expect on imaging. The maintained PDA is vital for early lung blood supply and development and can aid in repair.
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