1.What is “tetralogy of Fallot”? Tetralogy of Fallot is the most common form of cyanotic congenital heart disease. It consists of four malformations: (1) pulmonary artery stenosis, which can increase with age; (2) ventricular septal defect; (3) aortic span, where the normal aorta originates completely from the left ventricle, but in children with tetralogy of Fallot, part of the aorta originates from the left ventricle and the other part rides on top of the right ventricle. As age increases, the degree of right ventricular hypertrophy increases, which directly affects the function of the right ventricle. (4) right ventricular hypertrophy, which increases with age and directly affects right ventricular function. Therefore, the severity of tetralogy of Fallot often depends on the degree of pulmonary artery stenosis. There are many types of congenital heart disease, and they are divided into two categories: non-cyanotic and cyanotic, depending on whether the child is clinically cyanotic or not. The non-cyanotic congenital heart disease includes ventricular septal defect, atrial septal defect and ductus arteriosus, etc. These children usually do not appear cyanotic, but temporary cyanosis can occur when crying or breath-holding; cyanotic congenital heart disease includes tetralogy of Fallot, aortic dislocation, etc. These children usually have persistent cyanosis when quiet. 2.How to detect “tetralogy of Fallot” at an early stage? The earliest manifestation of tetralogy of Fallot is cyanosis after birth, especially in superficial parts of the body, such as the lips, nail beds of the fingers and toes, and the conjunctiva of the eyes, etc. The cyanosis can be significantly aggravated when the child cries. The child often has squatting symptoms, often squatting for a moment while walking or playing. In addition, in older children, long-term hypoxia causes capillary dilation and hyperplasia at the ends of fingers and toes, as well as hypertrophy of local soft and bone tissues, resulting in drumstick-like enlargement of fingers and toes, commonly known as “pestle-like fingers (toes)”. The above symptoms and phenomena should be highly suspected in children with tetralogy of Fallot. The expert tips] For children suspected of having tetralogy of Fallot, they should go to the hospital in time to avoid delaying the diagnosis and timely treatment. Early diagnosis and early treatment of tetralogy of Fallot can help improve the immediate and long-term results of surgery in children. What is “hypoxic attack”? Children with tetralogy of Fallot sometimes have paroxysmal dyspnea, increased cyanosis, and in severe cases, sudden onset of double eye rolling, staring, limb tonicity or convulsions and fainting, which is called “hypoxic attack”. In this case, parents should not panic too much, first of all, keep the child lying down; unbutton the child’s collar to keep the respiratory tract breathing usually; at the same time, bend the child’s knees, close to the chest, after this treatment most children can be relieved within a few minutes on their own, if not relieved should be rushed to the nearest hospital rescue. In order to avoid the occurrence of “hypoxic attack”, the child should drink more water, avoid violent crying, keep the stool usual, reduce constipation, etc., to reduce the triggering factors of “hypoxic attack”. 3.What tests should be done to confirm the diagnosis of tetralogy of Fallot? To confirm the diagnosis of tetralogy of Fallot, chest X-ray, electrocardiogram, cardiac echocardiogram and color multispectral and cardiac catheterization and cardiovascular angiography are usually required. Echocardiography is similar to a “moving picture” and can show the structure of the heart during motion. Cardiac catheterization and cardiovascular angiography are performed by inserting a plastic catheter into the cardiac cavity through the peripheral blood vessels to perform cardiac cavity and angiography. The information is crucial to the choice of surgical method. In addition to the structural abnormalities of the heart itself, a comprehensive examination of the child’s blood picture, liver and kidney function, and coagulation function is usually required before surgery. This information will facilitate the arrangement of treatment plan during and after surgery. The three-dimensional echocardiogram is a computerized three-dimensional reconstruction of a series of usually two-dimensional ultrasound images, which can display the heart chambers, intracardiac structures, large blood vessels and their relationship to each other, as well as the condition of heart activity, and is of great value in the diagnosis of congenital heart disease. 4.When is the best time to operate for tetralogy of Fallot? Once a child is diagnosed with tetralogy of Fallot, he or she has an indication for surgery. However, when is the best time for surgery? At present, it is thought that around the age of 1 year is appropriate. This is because infants younger than 1 year of age are less tolerant of surgical blows, and children older than 2 years of age may have secondary cardiac pathologies such as more severe pulmonary stenosis and increased right ventricular hypertrophy, which may affect the outcome of surgery. The child with severe “hypoxic attack” needs to undergo emergency surgery. If a child has life-threatening symptoms, such as a severe hypoxic attack, emergency surgery should be performed within 24 to 48 hours. 5.What is the surgical method for Tetralogy of Fallot? There are two types of surgery for tetralogy of Fallot: (1) Decompression surgery: These children have poorly developed pulmonary arteries and require initial enlargement of the pulmonary arteries. The purpose of both procedures is to improve the degree of cyanosis and to promote the development of the pulmonary artery in preparation for the next radical surgery. (2) Radical surgery: For children with well-developed pulmonary arteries, a one-time radical surgery can be performed, which means that the surgery can correct the pulmonary stenosis, repair the ventricular septal defect and correct the aortic span at the same time, so that the heart structure of the child can be completely corrected. Some children may have residual obstruction and ventricular septal defect, which sometimes need to be corrected by reoperation in time; some children have slow recovery of cardiac function after surgery, and need to take medication to improve cardiac function for 3-6 months; some children may have heart rhythm disorders, which need long-term monitoring. All children with tetralogy of Fallot surgery need regular review and follow-up after surgery. Digoxin is a cardiotonic drug often used after surgery for congenital heart disease. It can enhance the contraction of the heart muscle and slow down the heart rate, thus increasing the heart beat volume and improving the systemic circulation. However, the therapeutic and toxic doses of digoxin are close to each other, especially in children with poor cardiac function, liver and kidney dysfunction, electrolyte disorders, and after massive diuresis. The most common manifestation of digoxin poisoning in children is cardiac arrhythmia, followed by gastrointestinal symptoms such as nausea and vomiting. In order to prevent digoxin poisoning, besides taking digoxin on time and in the right amount, we should also pay attention to avoid taking calcium and pay attention to potassium supplementation. If a child has symptoms such as precordial discomfort, panic, nausea and vomiting after taking digoxin, we should be alert to digoxin poisoning and go to the hospital for electrocardiogram and digoxin blood concentration testing in a timely manner, as well as for necessary treatment.