[A rare form of aortic arch anomaly: left aortic and right descending aortic arch].

Among aortic arch anomalies, the circumflex aortic variety, involving left aortic and right descending aortic arch, is a rare situation. Two children were recently sent to the CCML for signs of tracheobronchial compression leading to the discovery of this anomaly. The younger child, aged 2 months, had been intubated since birth, and angiography presented a constrictive form of the disorder due to the presence of a small arterial canal linking the pulmonary tree to an aberrant right subclavian artery arising from a voluminous Kommerel diverticulum. Removal of the obstacle was achieved by section of the arterial channel approached via a right posterior thoracotomy. The second patient, aged 7 years, had chronic bronchopneumonia with severe obstructive syndrome. Multislice CT investigation with three-dimensional reconstruction showed obstruction at two levels: the first concerned the lower part of the trachea related to the posterior transverse segment of the aortic arch; the more severe second obstruction was due to a vascular pinch formed by the descending aorta and the right pulmonary artery. Improvement in functional signs with time reported by the parents had led to temporisation in this case. In adults this anomaly is often a fortuitous finding during radiological investigations performed for slight functional signs. In all cases of aortic anomalies and associated lesions, the importance of precise and thorough investigation using modern radiological techniques must be stressed.