Absence of the pulmonary artery

Absence of the pulmonary artery, also known as unilateral absence of a pulmonary artery (UAPA), is a rare congenital cardiovascular malformation in which one of the two main pulmonary arteries fails to develop during embryonic life. This condition results from the involution or malformation of the proximal portion of the sixth aortic arch on the affected side. The absent pulmonary artery is most commonly the right pulmonary artery, though left-sided absence also occurs and is more frequently associated with other congenital heart defects such as tetralogy of Fallot, septal defects, patent ductus arteriosus, and coarctation of the aorta. The lung on the affected side receives its blood supply through collateral systemic arteries, typically bronchial arteries, which are often insufficient for normal gas exchange. Clinically, patients may present with recurrent pulmonary infections, hemoptysis (coughing up blood), exercise intolerance, dyspnea (shortness of breath), and pulmonary hypertension affecting the contralateral lung, which must accommodate the entire cardiac output from the right ventricle. Some patients remain asymptomatic into adulthood and are diagnosed incidentally on chest imaging, while others develop significant symptoms in infancy or childhood. Massive hemoptysis from hypertrophied bronchial collateral vessels can be a life-threatening complication. The condition primarily affects the cardiovascular and respiratory systems. Management depends on the severity of symptoms and associated anomalies. Treatment options include surgical revascularization (reimplantation or reconstruction of the absent pulmonary artery) when feasible, particularly in younger patients, embolization of collateral vessels in cases of hemoptysis, and in severe cases, pneumonectomy of the affected lung. Pulmonary hypertension in the contralateral lung may require targeted medical therapy. Long-term follow-up with cardiology and pulmonology is essential, as complications can develop or progress over time. Early diagnosis and intervention generally lead to better outcomes.

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