Single ventricle, also known as common ventricle and double inlet ventricle, is a defect in the sinus and/or septum of one or both ventricles of the heart with only one ventricular cavity that receives blood from both the right and left atria through two atrioventricular valve orifices or common atrioventricular valve orifices. The incidence of this disease is 1.5%-3% of precardiac disease, with a male:female ratio of approximately 2-4:1. Single ventricle often coexists with other complex malformations of the heart, such as complete pulmonary vein ectopic drainage and aortic arch dissection. Patients with univentricular ventricles commonly have visceral inversions, such as absence of spleen syndrome or multiple spleen syndrome, and atrial anomalies. Single ventricle has been one of the difficulties in cardiac surgery treatment due to its special pathophysiological characteristics. After nearly 20 years of efforts, 90% of patients with single ventricle have good quality of life through treatment and can have children and participate in sports activities. Depending on how much pulmonary blood is present, treatment options for single ventricle vary. Single ventricle with little pulmonary blood has an arterial shunt after birth to promote the development of the pulmonary arteries and improve hypoxemia; a bidirectional Glenn procedure after 2.5-3 months and a total cavopulmonary anastomosis (TCPC) after 1.5-2 years of age. Single ventricle with a lot of pulmonary blood should first have pulmonary artery banding to prevent the development of pulmonary hypertension; bidirectional Glenn procedure should be done after 2.5-3 months and total cavopulmonary artery anastomosis should be completed after 1.5-2 years of age. For various double-entry type single ventricle, if the two sides of the ventricle are well developed, the second and third cusps are well developed, and the large artery relationship is normal, septal reconstruction can be done. During the treatment of single ventricle, it is important to insist on early treatment and systematic treatment, as well as individualized treatment, only in this way can more patients with single ventricle be treated effectively, otherwise there will be many patients who cannot be treated because of pulmonary hypertension or poor pulmonary artery development. Type A: pure left ventricular development without right ventricular sinus section, only one right ventricular funicular stump attached to the left ventricle, 78% of patients with single ventricle are in this category. Type B: Pure right ventricle without a left ventricular sinus, in about 5% of patients. Type C: undeveloped ventricular septum or only residual septal tissue, in about 7% of patients. Type D: Both the right and left sinuses and septum are developed, accounting for 10% of patients. Each of the above types is further divided into four subtypes according to the interrelationship of the great arteries. Type I is normal for the relationship of the great arteries; Type II is right transposition, that is, the aortic valve orifice is located in the right front of the pulmonary valve orifice; Type III is left transposition, that is, the aortic valve orifice is located in the left front of the pulmonary valve orifice; Type IV is inversion, that is, the aortic valve orifice is located in the left posterior of the pulmonary artery. Among them, type AIII single ventricle is the most common. The left ventricle receives blood from the left and right atria, and part of the blood goes directly to the pulmonary artery, while the other part enters the aorta through the bulbous orifice. After the shunt pathway is established, the changes in arterial partial pressure of oxygen, heart rate and blood pressure should be closely monitored. An arterial partial pressure of oxygen in the range of 80-85% indicates a moderate shunt. If the arterial partial pressure is below 80%, surgical technique, low shunt volume, or distal pulmonary stenosis should be suspected. Arterial oxygen partial pressure above 85% should be considered an excessive shunt, especially if it is accompanied by an arterial diastolic pressure below 25-30 mmHg. To prevent excessive shunting, the size of the Gore-tex prosthetic vessel is critical. With an average neonatal weight of 3-4 kg, a 3.5 mm Gore-tex vessel is appropriate. In neonates with small body weight, the proximal anastomosis is positioned as distal to the right subclavian artery as possible and not done on the innominate artery or its proximal end to avoid excessive shunting. For those weighing less than 3 kg, a 3 mm Gore-tex prosthesis is used. 5-6 kg children can also use a 3.5 mm Gore-tex prosthesis, but many of these children are older than 2-3 months and can undergo the Glenn procedure directly. Is the arterial catheter tied? This question is often asked of children who are dependent on an arterial catheter for survival. The advantage of keeping the catheter in place is that it can save the patient’s life if a thrombus forms in the shunt vessel. The disadvantage of keeping the arterial catheter in place is the risk of excessive pulmonary blood and ventricular volume loading before the catheter closes spontaneously and, on the other hand, the risk of non-closure of the arterial catheter. In the experience of Boston Children’s Hospital, they ligate large arterial conduits or children with an alternative source of pulmonary blood, for example, antegrade blood flow through a narrowed pulmonary artery, and do not ligate arterial conduits with atresia of the pulmonary artery for such conduits.