RESUMO
Aorto-pulmonary window (APW) is a rare congenital heart defect characterized by the connection between the ascending aorta and the pulmonary trunk before its bifurcation, just above the semilunar valves, due to the abnormal development of spiral septum. The short-axis echocardiographic view of the right ventricular outflow track, the three-vessel-view, and the three-vessel-trachea view are the key planes for prenatal diagnosis. We report a case of APW with absent ductus arteriosus in a monochorionic twin, detected by prenatal echocardiography. The diagnosis was confirmed postnatally and corrective surgery was performed at the age of 1 week. Prenatal diagnosis of APW is essential, since surgical correction early after birth is required to prevent congestive heart failure secondary to high pulmonary blood flow.