FIG 51.6 Features of aortopulmonary windows (A) Example in the setting of interruption of the aortic arch at the isthmus, with the arterial duct supplying the distal circulation from the pulmonary trunk The arterial trunks are photographed from the front (B) A large defect (dashed line) viewed subsequent to opening the aorta Note the presence of the separate aortic and pulmonary roots FIG 51.7 A small aortopulmonary window as seen from the pulmonary trunk (A) and a large aortopulmonary window extending to the margins of the pericardial cavity as seen from the aortic aspect (B) Note the presence of the anomalous origin of the left coronary artery from the pulmonary trunk (A) and the origin of the right pulmonary artery from the aorta (B) When larger, the defects extend more distally toward the margins of the pericardial cavity The largest windows can occupy most of the adjacent area between the intrapericardial arterial trunks (see Figs 51.6B and 51.7B) When the deficient area reaches to the margins of the pericardial cavity, it is frequent to find aortic origin of the right PA, oftentimes also in association with interruption of the aortic arch (see Fig 51.6) Association with origin of the left coronary artery from the pulmonary trunk is also frequent (see Fig 51.7A) The prevalence of AP window in patients with congenital heart disease is 0.1% to 0.2%.11,12 AP window can occur as an isolated lesion, or it can be associated with other cardiac abnormalities in 30% to 50% of cases,11,13,14 the most common of which are arch abnormalities, specifically interrupted aortic arch (commonly type A) and coarctation of the aorta, and rarely VSD, tetralogy of Fallot and transposition of great arteries Mori and colleagues classified AP window into three types: proximal (type I), distal (type II), and total (type III) This classification was recently modified with the addition of an intermediate category (type IV) (Fig 51.8).15 Interrupted aortic arch in the setting of AP window is not usually associated with DiGeorge syndrome, suggesting a distinct malformation unrelated to “conotruncal” abnormalities.16 Abnormal origin of the coronary arteries is common, with the coronary arteries arising frequently from the edge of the defect The size of the communication in an AP window is variable, but they are generally large, unrestrictive, and hemodynamically significant In rare cases the AP window can be small and pressure restrictive Iatrogenic/traumatic AP window has been reported following balloon angioplasty of the PAs, after PA stent placement for supravalvar pulmonary stenosis in post–arterial switch patients.17–19 FIG 51.8 Classification of aortopulmonary window according to the Society of Thoracic Surgeons (From Backer CL, Mavroudis C Surgical management of aortopulmonary window: a 40-year experience Eur J Cardiothorac Surg 2002;21:773–779)