Extrapericardial origin of the entirety of the left pulmonary artery in the absence of a pulmonary arterial sling.

We report the findings at autopsy for an infant with respiratory distress and hypoplastic left lung. The left pulmonary artery, in its entirety, took origin extrapericardially from the right pulmonary artery in the absence of tracheobronchial encirclement. We speculate that it was abnormal course of the left pulmonary artery that produced the hypoplasia of the left lung due to compression of the main left bronchus.