The course of the anomalous left pulmonary artery to the right of the trachea produces deviation of the lower trachea to the left with resulting compression of the right mainstem bronchus and lower trachea. This results in airway obstruction that affects primarily the right lung, although compression of the lower trachea and left mainstem bronchus can result in bilateral obstruction. Other abnormalities in the arterial supply to one or both lungs can be seen in association with this abnormality. On occasion, the anomalous pulmonary artery may supply only the left upper lobe with normal pulmonary arterial supply to the left lower lobe. In addition, partial anomalous supply of the right upper lobe of the lung from the anomalous left pulmonary artery has been described.
Survival is unlikely without surgical intervention.
Mortality is variable and has been reported to be relatively high in previous studies. The major contributor to postoperative mortality is the high frequency of bronchial and tracheal abnormalities in this group of patients. Early, aggressive intervention may minimize the mortality caused by these associated lesions. Morbidity includes frequent episodes of stridor and respiratory distress with or without wheezing and cyanosis. Recurrent pneumonia can occur.