Lifetech AcuMark™ Sizing Balloon Post-Market Clinical Follow-up Study

Inclusion Criteria:

1. Patients who have been confirmed with single secundum atrial septal defect (ASD) byechocardiography;

2. The anatomy of ASD is suitable for percutaneous closure;

3. Patients are scheduled to perform ASD closure;

4. Patients or legally authorized representative(s) who are willing and capable ofproviding informed consent.

Exclusion Criteria:

1. Any contraindication for ASD closure;

2. Patients have ostium primum ASD or coronary sinus ASD;

3. Patients who are pregnant or breastfeeding;

4. Patient is currently participating in another clinical trial that has not yetcompleted its primary endpoint.