This 11-month-old girl was seen because of persistent wheezing. Laboratory evaluation included determination of white blood cell count, and hemoglobin and electrolyte levels. All results were normal. Chest roentgenograms were obtained (Figs 1 and 2), as was a barium esophagogram (Fig 3). Pertinent medical history included multiple clinical episodes of wheezing and stridor, which was present since birth. Growth and development were normal.
Denouement and Discussion
Pulmonary Sling Anomaly of the Left Pulmonary Artery
Pulmonary sling anomaly of the left pulmonary artery is a condition in which the left pulmonary artery originates from the right pulmonary artery. It is an uncommon congenital anomaly of the pulmonary arteries and may produce severe airway obstruction. The usual origin of the left pulmonary artery from the main pulmonary artery trunk is not demonstrated. The left pulmonary artery, arising from the distal right pulmonary artery, supplies the entire left lung. The embryology of this condition results from a defect of the left sixth aortic arch (from which the pulmonary arteries arise) such that the left lung is supplied y a collateral branch of the right pulmonary artery. This ollateral left branch courses to the left side behind the trachea and anterior to the esophagus at or slightly above he level of the carina. The compression from this vessel may cause airway obstruction affecting the right lung, the lower trachea, and/or the left main-stem bronchus.