Bronchial Obstruction Due to Pulmonary Artery Anomalies. I. Vascular Sling

The authors report three cases of respiratory embarrassment in infants from compression of the right bronchus and trachea by a "vascular sling" formed by an aberrant left pulmonary artery coursing anterior to the right main-stem bronchus and posterior to the trachea. Five similar cases have been described in earlier literature. The embryologic origin of this anomaly appears to be a disturbed time-sequence in the growth and union of the left pulmonary artery and the left lung bud. The clinical symptoms are those of respiratory distress in the neonatal period produced by tracheobronchial compression, associated with obstructive emphysema of the right lung. Bronchoscopic examination reveals extrinsic pressure on the right bronchus and posterior wall of the trachea. The esophagram does not reveal any posterior indentation and is thereby helpful in distinguishing this entity from the more common "vascular ring" which is a systemic arterial malformation causing constriction of the trachea and esophagus. Early recognition of an anomalous left pulmonary artery is particularly important in view of the fact that the condition can be corrected surgically.