Objective      To investigate the effects of the fibrinolytil on the two different anticoagulation protocols after transcatheter closure of atrial septal defect (ASD) and the significance.       Methods      Eighty-five ASD patients who successfully underwent transcatheter closure of ASD were randomly divided into a low-molecular-weight heparin group (LMWH group) and a prolonged low-molecular-weight heparin group (pLMWH group). ELISA was applied for detecting the levels of tissue plasminogen activator (tPA) and D-Dimer at different time points including before the operation

immediately after the operation

and 1

2

3

7

30 and 90 d after the operation.       Results      Before the operation

the levels of tPA and D-D dimer showed no significant difference between the pLMWH group and the LMWH group. The levels of tPA and D-D dimer of the two groups immediately after the operation increased significantly as compared with those before the operation

and reached their peak levels (P0.05). The levels of tPA and D-D dimer declined slightly on 1 d and 2 d after operation (P0.05)

then decreased to be close to the baseline on 3 d

and returned to the baseline on 7

30 and 90 d.       Conclusion      The fibrinolytic system is transiently activated after transcatheter closure of ASD and returns to baseline on day 3 after operation in both the LMWH group and the pLMWH group.