Surgery for the correction of complex congenital heart disease includes palliative surgery or primary radical surgery. In recent years, with the improvement of cardiac surgery and related technologies, many complex congenital heart diseases can be radically treated in infancy and early childhood with one-stage radical surgery, but palliative surgery still has an irreplaceable role in the treatment of some newborns and infants with severe or complex congenital heart diseases. For infants and children with severe hemodynamic effects, acute severe hypoxia or extreme physical weakness that cannot tolerate radical surgery or whose pathologic and anatomic features do not allow for primary radical surgery, palliative surgery can improve clinical symptoms and create conditions for radical surgery. At present, palliative surgery is not considered as the final treatment, but is performed within a short period of time after palliative surgery. Therefore, close follow-up and review should be performed within six months or one year after palliative surgery, so that timely second-stage surgery can be performed without losing time. Palliative surgery mainly includes body-pulmonary artery bypass, central bypass, pulmonary artery circumferential reduction, vena cava-pulmonary artery bypass (Fontan-type surgery) and atrial septal stoma. I. Body-pulmonary artery shunts Body-pulmonary artery shunts were used clinically by Blalock and Taussig in 1945 and are in decline as the outcome of phase I radical surgery for complex congenital heart disease has improved, however, shunts are still indicated for some complex congenital heart diseases that cannot be cured or have a high mortality rate during phase I radical surgery in infancy and childhood. However, bypass is still indicated for complex congenital heart disease that cannot be treated or has a high mortality rate in infancy. The purpose of bypass is to increase pulmonary blood flow and improve cyanosis and other symptoms; expand the pulmonary vascular bed and promote pulmonary vascular development to facilitate phase II radical surgery. Therefore, shunt is mainly used in complicated cyanotic congenital heart disease with severe pulmonary artery dysplasia that cannot be treated by stage I radical surgery or vena cava-pulmonary artery shunt. The purpose of central shunt is to relieve right ventricular outflow tract obstruction and promote pulmonary vascular development. The right ventricular outflow tract and pulmonary artery trunk are enlarged with a patch under direct vision using extracorporeal circulation to promote pulmonary vascular development. The central shunt is a modified Brock procedure with extracorporeal circulation. Enlargement of the right ventricular outflow tract and pulmonary artery is indicated for children with moderate or severe or greater hypoplasia of the right and left pulmonary arteries, but with the presence of a main pulmonary trunk or a short atretic segment of the main pulmonary trunk. The procedure is performed under parallel extracorporeal circulation. A longitudinal incision of the right ventricular outflow tract is made, extending upward across the atretic segment to the main pulmonary artery, and a portion of the hypertrophied myocardium of the funnel is removed to create an intraventricular right ventricular access of at least 8-10 mm, followed by suturing of the right ventricular outflow tract to the pulmonary artery incision with an autologous pericardial slice or a flap-bearing homograft slice. Unless the distal pulmonary artery is severely hypoplastic, pulmonary blood flow is determined by the degree of right ventricular outflow tract sparing, so the width of the patch should be less than the standard for right ventricular outflow tract sparing at the time of radical surgery; otherwise, it is prone to postoperative pulmonary blood overload and acute pulmonary edema. The advantage of this procedure is that it promotes moderate and severe pulmonary vascular dysplasia better than body-pulmonary artery bypass. The disadvantage is that the width of the patch and the degree of right ventricular outflow tract sparing are not easy to master. The main complication of this procedure is stenosis at the left pulmonary artery opening, therefore, extension of the incision to the left pulmonary artery and oversized patches should be avoided, as oversized patches can also lead to aneurysmal dilatation of the right ventricular outflow tract. In addition, this procedure can also be used as a fallback for tetralogy of Fallot or pulmonary artery atresia undergoing primary radical surgery due to difficulty in stopping the pulmonary artery due to dysplasia. If the right/left ventricular pressure ratio is >0.85 after resuscitation, the ventricular defect patch should be removed or perforated to properly narrow the evacuated right ventricular outflow tract and pulmonary artery. For those with anomalous vessels crossing the right ventricular outflow tract or long atretic segments of the pulmonary artery, some surgeons choose to make a right ventricle-pulmonary artery connection with a prosthetic vessel without a valve or with a homogeneous vessel. The right ventricle-pulmonary artery connection with a prosthetic vessel without a valve has the disadvantage of progressive stenosis of the right ventricular anastomosis and poor long-term outcome, and this procedure is rarely used. A right ventricle-pulmonary artery interposition allograft reduces the risk of pulmonary stenosis while preserving the activity of the pulmonary valve and reducing pulmonary regurgitation. The timing of second-stage radical surgery after central shunt depends on the assessment of pulmonary vascular development, with a predicted right/left ventricular pressure ratio <0.85 or preoperative lung >1.5 being considered for radical surgery. The McGoon ratio or Nakata index may also be used as a criterion for pulmonary vascular development. Pulmonary artery annuloplasty In 1952, muller and Dammann proposed the use of pulmonary artery annuloplasty as a reduction procedure for young children with congenital heart disease with large left-to-right shunts, such as giant ventricular septal defect or single ventricle. It was later gradually applied to treat congestive heart failure with a view to preventing further development of obstructive pulmonary vascular disease. With the improvement in the outcome of early radical treatment of septal defects, complete transposition of the great arteries, and some other lesions, this reduction procedure is no longer frequently used. The purpose of this procedure is to achieve sufficient effective atrial level traffic, increase the mixing of blood flow in the body-pulmonary circulation, and improve oxygen saturation. Balloon atrial septal stoma, plays an important role as a preoperative preparation for complete radical transposition of the great arteries with intact septum. Balloon atrial septal stoma is mainly used in neonates. If the child is older, the septum is thicker, and the result of balloon atrial septal stoma is unsatisfactory, atrial septotomy can be performed via the right atrium under normothermia or extracorporeal circulation. With the improvement of early radical surgery, this procedure is now used only in children with complete transposition of the great arteries within the first week of life. V. Vena cava-pulmonary artery shunt (Fontan-like procedure) Greene procedure: For patients who are not suitable for atrial tamponade, or who are ready for modified atrial tamponade, Greene procedure (superior vena cava-pulmonary artery connection) is performed to improve hypoxia to reduce single ventricle load. Total vena cava-pulmonary artery connection, which is the connection of all the upper and lower vena cava to the pulmonary artery. The hemodynamic basis of the Fontan class procedure is based on the characteristic that the pulmonary circulation is low pressure and low resistance. The effect of increasing central venous pressure and left atrial diastole allows the pulmonary circulation to be established on a new basis. Therefore, the cardiac output after Fontan surgery is dependent on the blood flow in the pulmonary circulation, and the amount of blood flow in the pulmonary circulation is determined by the pressure difference between the pulmonary artery and the left atrium. In this respect, any factor that affects the pressure and resistance of the pulmonary vessels and increases them, and any factor that affects the smooth flow of vena cava blood into the pulmonary circulation, can affect the preload and beat volume of the left heart, which is a major contraindication for Fontan surgery. In conclusion, palliative surgery improves the patient’s hemodynamic status to some extent, improves the child’s hypoxemia, reduces congestive pneumonia and heart failure, improves the child’s tolerance of the disease, and gains time for further radical surgery. Although palliative surgery is gradually decreasing, it is undeniable that palliative surgery is still an indispensable means of correcting complex congenital heart disease in pediatric patients.