1, distinguish primary or secondary foramen atrial septal defect because the repair methods of these two defects are different, secondary foramen defect can be directly sutured; while primary foramen defect must be repaired with patch, and there is atrioventricular node (between atrioventricular ring and coronary sinus) and conduction bundle (at the upper edge of coronary sinus) damage caused. The risk of atrioventricular block, which in some patients can be combined with an anterior mitral valvular cleft, can easily produce mitral stenosis or incomplete closure if the suture is not appropriate. The method of determination is based on the location of the atrial septal defect in relation to the coronary sinus. The location of the primary foramen atrial defect is low and close to the tricuspid annulus, and the coronary venous sinus is lateral to it. 2, pay attention to the repair method of venous sinus type and inferior vena cava type atrial defect. If the lower edge of inferior vena cava type defect is completely absent, it is easy to mistake the inferior vena cava flap as the lower edge of the defect if no attention is paid to identify it. The most common combined malformation is the ectopic connection of right pulmonary vein. When repairing the atrial septal defect, the ectopic pulmonary vein should be separated into the left atrium, and it should not affect the right pulmonary vein opening to avoid stenosis. 4.After the resumption of atrioventricular block heart, when the ECG shows ° atrioventricular block, we should wait for a period of time to exclude factors such as low temperature, ionic disturbance, acid-base balance disturbance. If the ECG still shows ° AV block, a temporary pacemaker should be placed on the heart table, and the pacing heart rate should be adjusted to about 80 beats/min. If the heart rhythm recovers in a short time, the temporary pacing electrode can be removed; if the heart rhythm does not recover in a long time, a permanent pacemaker should be placed.