We present a 3-year-old boy born with anomalous hepatic venous drainage into the left atrium and a small sinus venosus atrial septum defect, in whom pulmonary arteriovenous malformations developed with progressive cyanosis. Surgical redirection of the hepatic venous drainage to the right atrium and closure of the atrial septal defect led to regression of the pulmonary arteriovenous malformations. However, in contrast to other reports, progressive pulmonary hypertension developed postoperatively.