Atrial septal defect is not uncommon in our daily lives. Many patients with atrial septal defects often ask their doctor if they can swim. This has to be analyzed based on specific circumstances. If the atrial septal defect is not severe, and it's just a minor atrial septal defect, generally it does not affect the patient's daily activities, such as swimming or running. However, if the atrial septal defect is severe, especially if it has led to heart failure and heart enlargement, in this situation, one should definitely not engage in strenuous activities such as swimming or running.