Right atrial thrombosis: rare complication of the modified Fontan procedure.

A four-year-old boy with DORV and hypoplastic left ventricle underwent a modified Fontan procedure. He had a very difficult postoperative course complicated by continued pleural effusions. Eventually he died during a last ditch effort to ligate the thoracic duct at the right diaphragm. At autopsy, an obstructing giant thrombus was found in the right atrium. This rare complication probably was due to multiple factors, but we now anticoagulate all Fontan patients routinely in an effort to prevent this fatal problem.