Atrial thrombi after the Fontan operation.

This report documents four instances of right atrial thrombi discovered from four days to five years after Fontan-type operations. Two of the thrombi were removed at reoperation, and two diminished in size during anticoagulation therapy. There were no pulmonary emboli in this small series, but the ominous implications of right atrial thrombi in the post-Fontan situation are obvious. For this reason we recommend regular echocardiographic surveillance of all patients who have had the Fontan operation and anticoagulation in certain situations.