Anomalous course of left pulmonary artery with respiratory obstruction.

Anatomic variations of intrathoracic vessels, particularly of the aortic arch, are now well recognized as a cause of respiratory obstruction in infants and children. Although the variety is almost infinite, these anomalies may be classified into a few broad groups, depending on their anatomic course and the functional or physiologic disturbance which they produce. The true vascular rings, including the double aortic arch and the right aortic arch with a ligamentum arteriosum, encircle both the trachea and esophagus, giving rise to respiratory symptoms in at least 85 per cent of afflicted patients. A second group is made up of individual vessels of the aortic arch having an anomalous origin and course, arising contralaterally to their destined blood distribution and compressing either the trachea or esophagus in crossing the mid-line. The compression defect and symptoms depend on whether the vessel pursues a retro-esophageal, an ante-esophageal, a retro-tracheal, or a straight ante-tracheal course. The gro...