Aortopulmonary window

The aortopulmonary window (aortic-pulmonary window, AP window, APW) is the radiological space between the aortic arch and the left pulmonary artery, mainly described on the frontal chest conventional radiography.

It should not be confused with the aortopulmonary septal defect that is sometime also called aortopulmonary window (with the same acronym APW) .

The boundaries of the aortic-pulmonary window are the aortic arch superiorly, the left pulmonary artery inferiorly, the posterior watll of asending aorta anteriorly, the anterior wall of descending aorta posteriorly, the left lateral wall of trachea, left mains bronchus and esophagus medially, and the pleural surface of the left lung laterally. 

The aortopulmonary window contains the ligamentum arteriosum, the left phrenic, vagus and recutrrent laryngeal nerves, the left bronchial arteries and veins, the fat and some lymph nodes (left lower paratracheal lymph nodes (4L) and subaortic lymph nodes (5)).