<p>Atrial septal defects are one of the most common forms of congenital heart disease, however sinus venosus communications, particularly pulmonary vein-type defects, are rare and are easily misdiagnosed. Patients with pulmonary vein-type sinus venosus defects often present earlier than those with ostium secundum defects with significant right heart dilation. Correct diagnosis has important implications for management. We discuss the clinical courses and review multimodality imaging of three patients correctly diagnosed with pulmonary vein-type defects after an initial diagnosis of an ostium secundum atrial septal defect, in order to promote understanding of the unique anatomy of this entity.</p>