Tracheostenosis and bronchial abnormalities associated with pulmonary artery sling.

Three patients with aberrant left pulmonary artery (sling artery) are reported to illustrate associated tracheobronchial abnormalities. The clinical picture was that of severe episodic or progressive respiratory distress without dysphagia in early infancy. Striking narrowing of the trachea by complete "ring cartilages," unrelated to compression by the abnormal pulmonary artery, was present. Tracheotomy and intubation failed to relieve the obstruction. In one patient the bronchi and bronchial segmentation pattern were normal, but in the other two patients, bronchial abnormalities included wide irregular cartilages in the main bronchi, forming more complete rings than is normal. In both, the right main bronchus was relatively longer than normal, and the bronchus intermedius showed poor cartilage ring formation and was relatively short compared to the main bronchus. This discrepancy did not appear to be due to distal displacement of the right upper lobe bronchus. In these two patients the left main bronchus was relatively short and wide with reduced number of cartilage rings (five-six vs usual normal number of nine), so that the right and left main bronchi were almost of equal length. However, the branch patterns of the lobar bronchi were within normal range. Bronchoscopy seems essential to demonstrate such ring tracheal cartilages (absence of the pars membranacea of the trachea), which when found should alert the examiner to the possible presence of an abnormal left pulmonary artery. Since surgical correction of tracheal stenosis of this type is not possible at present, the ultimate prognosis of patients with sling artery may depend more on the severity of the tracheal anomaly rather than on success of surgical correction of the abnormal left pulmonary arterial course. Although aberrant (sling) left pulmonary artery can occur in patients without respiratory tract symptoms, tracheal stenosis due to ring tracheal cartilages occurs in a significant fraction of patients with this arterial anomaly. Bronchoscopic study of the trachea, and possibly air or contrast bronchography of right and left main bronchi, can be of aid in diagnosis of this complex.