The severity of a two-hole atrial septal defect is determined by the size of the defect and the presence or absence of other combined cardiac malformations. If the patient is asymptomatic and the defect is under 5 mm, this condition is not serious and many patients may carry the atrial septal defect for a lifetime without developing it. This condition can be kept under observation with regular review of cardiac ultrasound, noting the absence of pulmonary hypertension as well as right heart failure, etc. If the atrial septal defect is very large, greater than 36 mm, this is a larger septal defect and requires surgical open-heart treatment to seal the septal defect, which is a more serious type of condition. If patients with two-hole atrial septal defect are not treated regularly, serious arrhythmias, right atrial right ventricular enlargement, severe pulmonary hypertension, and right heart failure will occur in the later stages, which are also more serious types and should be treated with timely sealing. If a right-to-left shunt develops at the end stage, this is the most serious case, and the chance of surgery has been lost, and the 5-year survival rate is low.