Large thrombus formation from right atrial incision site after closure of atrial septal defect.

Atrial septal defect (ASD) is the common congenital anomaly which requires surgical interventions. Right atrial thrombus formations after primary suture repairs of the ASD and evidences of thromboembolic complications are extremely rare. Specifically, the cases of thromboembolic complications have high mortality and morbidity risks. Two cases of giant intra-atrial thrombus formation detected in the late stage after primary repairs of ASDs are being discussed.