LAUSR

Computed tomography angiography in a neonate presenting with cyanosis and failure to thrive revealed an aortopulmonary window with a 1.5-cm defect in the aortopulmonary septum just above the sinotubular junction (Figure 1). Interestingly, there was a crossed arrangement of the pulmonary arteries (PA) at their ostia, with the right PA ostium superior and to the left of the left PA. In addition, the left anterior descending artery arose from the right coronary artery with a pre-pulmonic course. Crisscross PA is a rare anomaly of PA origin where the right PA originates to the left of the left PA. The left PA ostium is invariably superior to the origin of the right PA. The combination of aortopulmonary window and crisscross PA was documented in a report in which the authors stressed its physiologic and hemodynamic implications as the right PA received increased pulmonary blood flow because its ostium was inferior and therefore abutted the window. Our case is unusual because the right Figure 1. Computed tomography angiography showing a defect in the aortopulmonary septum (black star) with crisscross pulmonary arteries. The right pulmonary artery (R) was seen arising superiorly and to the left of the left pulmonary artery (L). Associated anomalous origin of the left anterior descending artery from the right coronary artery with a pre-pulmonic course (black solid arrow) was also noted.