In front of the left bundle branch. Left anterior crossbeam plasty is a surgical technique to treat congenital heart defect, and it is a repair operation between left anterior crossbeam and ventricular septum. The left anterior bundle is a part of the cardiac conduction system, which is located in front of the left bundle branch. On one side of the interventricular septum, there is a bundle branch called left anterior bundle, which conducts to the front of the left ventricle. In plastic surgery, the surgeon will cut the chest, enter the heart and repair the left front beam. Repair includes sewing or using graft to repair the left front beam to improve the conduction function of the heart and correct congenital heart defects.