A ventricular septal defect is a hole or holes in the septum of the right and left ventricles, which can be large or small in diameter and can occur in any anatomical part of the septum. Ventricular septal defects can also be acquired, due to penetrating cardiac injury to the septum, or acute myocardial infarction causing perforation of the septum. However, congenital ventricular septal defects are the most common in clinical practice. It can exist alone or be a component of other complex precordial diseases. I. Incidence: Ventricular septal defect is the most common congenital heart disease, with a statistical incidence of 15.5% in the precordial heart. Pathologic anatomy and typing: According to the different parts, it is divided into: sub-stem ventricular defect, crestal ventricular defect, membranous ventricular defect and myocardial ventricular defect. Pathophysiology: The pathophysiology of ventricular septal defect is based on the hemodynamics of intracardiac left-to-right shunt and the amount of shunt flow, which increases the cardiac load and leads to myocardial hypertrophy, causing pulmonary vascular lesions and severe pulmonary hypertension, resulting in reverse shunt, resulting in cyanosis and even Eisenmenger syndrome. Clinical manifestations: If the defect is less than 0.5cm, the shunt flow is small, and there are no obvious symptoms; if the shunt flow is large, there is panic, chest tightness, and even dyspnea after activity, and sometimes emergency surgery is needed. In large defects, pneumonia and heart failure often appear, both of which are causal, and serious symptoms of hemoptysis are present. Signs are mainly a heart murmur that can be heard at the left edge of the sternum. Later, Eisenmenger syndrome appears with central cyanosis and pestle finger. Diagnosis: The diagnosis is mainly made by cardiac ultrasound, which reveals a ventricular septal defect. Surgical indications: According to the size of the defect, the severity of symptoms, the presence of pulmonary hypertension, choose surgery, generally 1 to 2 years old is the best time for surgery. Small ventricular defects have the possibility of self-healing, but those that have not closed by the age of 2 should be treated surgically. In case of large ventricular defects with high fractional flow and life-threatening conditions, urgent surgical treatment is required.