Heart failure after transvenous closure of atrial septal defect associated with atrial standstill and thiamine-responsive megaloblastic anemia.

Despite advances in device closure for atrial septal defect, post-closure heart failure remains a clinical problem in adult patients but is seen only rarely in children. An eight-year-old boy, who had been followed by a local pediatrician with the diagnosis of diabetes mellitus and congenital heart disease, was consulted to us for cardiac re-evaluation. Electrocardiography demonstrated absent P waves, and echocardiography revealed enlargement of the right ventricle and both atria and secundum atrial septal defect. With the diagnosis of atrial standstill, secundum atrial septal defect and thiamine-responsive megaloblastic anemia, acute heart failure developed after transvenous closure of the atrial septal defect, which improved dramatically with thiamine and supportive treatment.