I. What is ventricular septal defect Ventricular septal defect is a kind of congenital heart disease caused by interventricular blood flow traffic due to hypoplasia or poor fusion of various parts of the ventricular septum. Ventricular septal defect is the most common congenital heart disease, with an incidence of about 0.1-0.4% in newborns and accounting for 20-30% of all congenital heart diseases. Ventricular septal defect is the most common cause of infant and child visits for congenital heart disease. Second, what are the effects of ventricular septal defect on the affected children Ventricular septal defect has different sites and sizes. The septal tissue is made up of several different tissue components together. Some parts are composed of myocardial tissue and some parts are composed of fibrous tissue. The location and size of the septal defect can determine the effects it produces. Ventricular septal defects produce a left-to-right shunt at the ventricular level, and the amount of shunt flow depends on the size of the defect. If the defect is large, the blood flow in the pulmonary circulation increases significantly, and after flowing into the left atrium and ventricle, it flows into the right ventricle at the ventricular level through the defect opening and enters the pulmonary circulation, thus increasing the load on the left and right ventricles, increasing the size of the left and right ventricles, increasing the blood flow in the pulmonary circulation leading to an increase in pulmonary artery pressure, and increasing the systolic load on the right ventricle, and finally entering the phase of obstructive pulmonary hypertension, which can occur in both directions or right-to-left shunt. Symptoms and manifestations of ventricular septal defect A ventricular septal defect has a very typical heart murmur, by which the doctor can determine the size and location of the ventricular septal defect. However, at birth, the murmur produced by a ventricular septal defect is not very obvious, especially in larger ventricular septal defects. The murmur may be heard only when there is a significant flow of blood through the septal defect into the lungs. Smaller ventricular septal defects produce a louder murmur than larger ventricular septal defects. The murmur produced by a ventricular septal defect as it closes on its own is progressively louder. Think of a watering hose in a garden. If the water is allowed to flow out of the hose from the ground, the sound is minimal, but if you squeeze the outlet with your finger and make the water jet out, the sound is loud. The same is true for murmurs in ventricular septal defects. It is important to remember that a louder murmur does not mean a larger defect. With a large septal defect, the amount of blood flow through the septal defect into the lungs is excessive and congestive heart failure will occur, which will manifest itself primarily in growth and development, with no weight gain and poor development during the first few months. When the blood flow to the lungs through the septal defect is not excessive, the child’s growth is usually not affected and only mild symptoms, such as shortness of breath, occur. If the child grows well during the first few months, the size of the septal defect does not cause congestive heart failure, and the child can continue to be monitored. If congestive heart failure is already present in the first few months, surgical repair is often required. In older children, ventricular septal defects may manifest as weakness and reduced exercise tolerance compared to children of the same age.