Objective  To observe the efficacy and safety of low molecular weight heparin (LMWH) in treatment of children after transcatheter closure of atrial septal defects (ASD).   Methods  Totally 48 children at age of (8.4±2.1) years and weight of (22.4±7.8) kg were hospitalized in our department from July 2006 to August 2007 and diagnosed as ASD with defect of 6-24 mm by transthoracic echocardiography (TTE). They were randomized into 2 groups

LMWH group and common unfractionated heparin group (heparin group). LMWH was administered to LMWH group twice through subcutaneous injection in abdominal wall after occlusion

while unfractionated heparin was given by intervenous drop infusion for 24 h after occlusion. Activated partial thromboplastin time(APTT) and prothrombin fragment 1+2 (F1+2) levels were determined before occlusion of ASD

at 24 h and 48 h after device implantation. TTE were performed 1

3 months after occlusion of ASD.   Results  TTE follow-up had been performed in 43 cases. Neither thrombus on ASD occluders nor severe hemorrhage complications was found during the follow-up period. There was no significant difference between the 2 groups in APTT and F1+2 levels before occlusion. APTT of the heparin group was significantly prolonged at 24 h after occlusion (P0.01)

but returned to normal range at 48 h (P0.05)

however

such significant changes were not found in the LMWH group (P0.05). F1+2 levels of the 2 groups were significantly increased after occlusion (P0.01)

and no significant differences was seen between the 2 groups.   Conclusion  LMWH is a safe

effective and convenient anticoagulant in treatment of children after transcatheter closure of ASD.