A multicenter, randomized, parallel-controlled clinical trial to evaluate the efficacy and safety of a new atrial septal defect occluder, ReAces®, and delivery system for the treatment of atrial septal defect occlusion. Compared with the traditional atrial septal occluder, this new atrial septal occluder supports re-puncture after occluder implantation. Thus those patients who have undergone atrial septal defect closure with the novel device may be eligible for future radiofrequency ablation of atrial fibrillation or mitral valve intervention.

The trial is expected to enroll 128 patients who will be randomly assigned to the test group or control group in a 1:1 ratio. Patients in test group will received ReAces occluder，and the others the regular occluder.The experiment is scheduled to enroll 128 patients who will be randomly allocated to one of two groups: test or control. Patients in the test group will receive a ReAces occluder, while those in the control group will receive a standard occluder.The safety and efficacy of the two groups at 1 year after surgery will be compared.

Inclusion Criteria:

1. aged 18-70 years;
2. with congenital secundum atrial septal defect;
3. the maximal ASD diameter was ≤38 mm;
4. with atrial-level left-to-right shunt, with Qp/Qs shunt ratio ≥1.5:1, or TTE or clinical manifestations indicated the existence of defect that inducing overfilling of right atrium;
5. the distance from the margin of defect to coronary sinus, atrioventricular (AV) valve, and right superior pulmonary vein (RSPV) was ≥5 mm, according to the echocardiography measurements;
6. volunteered to participate in this study, and signed informed consents.

Exclusion Criteria:

1. ostium primordium ASD and sinus venosus ASD.
2. infective endocarditis and hemorrhagic disorders.
3. active thrombosis.
4. patients with severe pulmonary hypertension (mean pulmonary artery pressure measured by catheter > 30 mmHg) who are not taking targeted drugs
5. patients with a porous atrial septal defect that cannot be completely occluded by a single occluder.
6. with severe myocardial disorders or valvular disease not associated with ASD
7. infectious disease within the last 1 month, or uncontrolled infectious disease
8. bleeding disorders, untreated gastric or duodenal ulcers
9. thrombosis in left atrium
10. partial or total pulmonary vein ectopic drainage
11. left atrial septum, left atrial or left ventricular dysplasia
12. Patients whose size (too small for TEE probe, catheter size, etc.) or physical condition (active infection, etc.) makes them unsuitable for cardiac catheterization
13. Patients who are allergic to nickel
14. Patients with any contraindication to aspirin therapy (except for those able to take other antiplatelet agents for 6 consecutive months).
15. Pregnant or lactating women and those who plan to become pregnant during the trial
16. Patients with a life expectancy of <12 months or those who are unable to complete the study's prescribed follow-up schedule
17. Participation in another clinical trial of a drug or medical device within 30 days prior to screening.
18. Patients who have previously undergone surgical atrial septal defect repair or percutaneous interventional atrial septal defect closure.
19. Patients who, in the opinion of the investigator, are not suitable for participation in this study.