Aortopulmonary window (radiograph)

The aortopulmonary (aortic-pulmonary or AP) window is a radiological mediastinal space seen on frontal chest x-rays.

Terminology

Beware that theThe term aortopulmonary"aortopulmonary window" can also refer to a rare form of congenital heart disease, usually referred to with the acronym APWinstead of AP window, where there is an opening between the aorta and the pulmonary trunk ⁴. It is usually referred to with the acronym APWinstead of AP window.

Also, be careful not to confuse the AP window with the aortic-pulmonary stripe.

The The term should also not be confused with an aortopulmonary septal defect (on on occasion is also called an aortopulmonary window).

Gross anatomy

Boundaries

The AP window boundaries boundaries are ^{1, 2}:

• superior: inferior wall of the aortic arch
• inferior: superior wall of the left pulmonary artery
• anterior: posterior wall of the ascending aorta
• posterior: anterior wall of the descending aorta
• medial: trachea; lateral wall of the left main bronchus; oesophagus (anterior to posterior)
• lateral: pleural surface of the left lung contacting the superior boundary (aortic arch) and extending to the inferior boundary (left pulmonary artery)

Contents

A variety of structures traverse the AP window ^1-3:

• left phrenic nerve
  • left recurrent laryngeal nerve
• left vagus nerve
• left bronchial arteries
• ligamentum arteriosum
• fat
• lymph nodes

Radiographic appearance

The AP window normally has a concave lateral border. A straight lateral border can be considered normal if unchanged from the previous chest x-ray. A newly straightened or convex lateral border is considered abnormal and has a number of causes ^{1, 2}:

• mediastinal lymphadenopathy (most common ³)
• prominent mediastinal fat (normal variant ³)
• aortic or bronchial artery aneurysms
• malignancy - e, e.g. nerve sheath tumour