1. What is tetralogy of Fallot a disease? Tetralogy of Fallot is the most common form of cyanotic congenital heart disease. The French scholar Etienne-Louis, Arthur, Fallot described the disease clinico-pathologically in 1888. He highlighted four fixed features of this congenital heart disease, which led to the name of Fallot’s tetralogy. Some scholars have also translated it as Fallot tetralogy, Faro tetralogy, and so on. Nowadays, it tends to be uniformly translated as tetralogy of Fallot. 2.What is the cause of Tetralogy of Fallot? The exact cause of tetralogy of Fallot is not known. Possible causes are maternal viral infection in early fetal life; environmental contamination, including food, air and water pollution; chromosomal defects; and genetic predisposition. 3.What is the difference between the heart of a patient with tetralogy of Fallot and a normal person? In general, the heart of a patient with tetralogy of Fallot has right ventricular outflow tract stenosis, ventricular septal defect, aortic riding, and right ventricular hypertrophy. The right ventricular outflow tract here includes the right ventricular funnel, pulmonary valve, pulmonary valve annulus, main pulmonary artery, and right and left pulmonary arteries. 4.How to determine the severity of tetralogy of Fallot disease? Just as there are mild and severe upper respiratory tract infections, the severity of tetralogy of Fallot varies as well. The key factor in determining the severity of tetralogy of Fallot is the location and degree of right ventricular outflow tract stenosis. The closer the size of the pulmonary valve, pulmonary annulus, main pulmonary artery, and left and right pulmonary artery diameters are to normal, the less severe the disease, the less risky the surgery, the better the surgical outcome, the smoother the postoperative recovery, and the more satisfactory the long-term postoperative results. When the stenosis of the right and left pulmonary arteries reaches a certain level, patients need staged surgery. In addition, if the combination of one side of the pulmonary artery is absent or combined with a single coronary artery malformation, etc., it will obviously significantly increase the risk of surgery. 5.What are the clinical manifestations of tetralogy of Fallot? The initial clinical manifestations of tetralogy of Fallot depend on the degree of right ventricular outflow tract stenosis. The most common case is only a slight bruising of the end of the mouth, lips, and extremities at birth. As the right ventricular funicular stenosis worsens with age, the end-edge bruising of the mouth, lips, and extremities worsens. In some patients, there is a sudden onset of extreme reduction in pulmonary blood flow and an increase in right-to-left shunt at the ventricular level, and the patient experiences an episode of hypoxia caused by extreme hypoxia in the body circulation. This is manifested by the upward turning of the eyes; increased bruising at the end of the mouth and lips and extremities; bruising of the face and trunk; increased heart rate; and irritability of the patient. Patients who are a little older have decreased activity and often prefer to squat after exertion. They increase the resistance of body circulation by squatting to reduce the right-to-left shunt at the ventricular level and achieve self-reduction of symptoms. Patients with combined gross pulmonary collaterals can develop congestive heart failure. In older patients with severe cyanosis, due to the abundant bronchial artery collateral circulation, patients may develop hemoptysis if rupture occurs. 6.What is meant by coarctation of the pulmonary collateral? In patients with tetralogy of Fallot, pulmonary blood flow is supplied through anomalous vessels between the aorta and the pulmonary artery due to stenosis of the pulmonary artery. These anomalous vessels can originate from the cephalobrachial vessels, the descending aortic arch, and the thoracoabdominal aorta. The presence of these vessels alleviates the patient’s hypoxia to some extent, but increases the burden on the heart and makes surgical treatment and postoperative recovery difficult. 7.Does a patient with tetralogy of Fallot have other problems in other parts of the body besides the heart malformation? In addition to the heart malformation, 11-35% of patients with tetralogy of Fallot have chromosome 22q11 deletion. This chromosomal abnormality is significantly associated not only with hypoparathyroidism, immunodeficiency, and neurological developmental defects, but also with aortic arch and cephalobrachial vascular malformations. In children with trisomy 21, 5% of the patients have tetralogy of Fallot. 8. How is the diagnosis of tetralogy of Fallot made? In addition to the patient’s medical history, clinical manifestations, chest X-ray and electrocardiogram, echocardiography is the main test. If the echocardiogram reveals dysplasia of the pulmonary artery, or if there is a suspicion of coarse body pulmonary collateral, or if the patient’s clinical presentation is not consistent with the objective examination, a pulmonary artery and aortography are needed to clarify the surgical approach and whether coarse body pulmonary collateral blocking is needed at the same time. CT examination is also a good tool, but if coarse body pulmonary collateral is found, aortography and collateral blocking are still needed. 9. What is the natural prognosis of tetralogy of Fallot? The natural prognosis of tetralogy of Fallot is poor. Natural death without surgery is 25% up to 1 year of age, 40% up to 3 years of age, 70% up to 10 years of age, and 95% up to 40 years of age. The natural prognosis depends on the degree of right ventricular outflow tract stenosis. The vast majority of patients die from hypoxia or heart failure. The prognosis is worst in those with cyanosis found after birth. 10. What is the optimal age for surgery in tetralogy of Fallot? The clinical decision on the best time to operate for a particular disease depends on the consequences of not operating at a given time, the mortality rate, the cost of the operation, the complications of the operation and the long-term outcome and survival of the operation. A joint European multicenter clinical study found that the operative mortality rate in children younger than 3 months was more than 5 times that of children in the older age group. The younger the child, the greater the chance of widening the right ventricular outflow tract across the pulmonary valve annulus during radical surgery for tetralogy of Fallot, the greater the likelihood of distant pulmonary valve closure insufficiency, the lower the long-term survival rate, the higher the cost of surgery, and the greater the difficulty of postoperative airway management. For these reasons, we believe that the optimal age for surgery is 6 to 11 months if the patient has no hypoxic episodes or heart failure occurring. 11. Can a single surgery for tetralogy of Fallot solve the problem? The vast majority of tetralogy of Fallot can be solved with a single surgery. However, if the diameter of the right and left pulmonary arteries is too small to meet a certain standard, a body-pulmonary bypass is needed first, and then the diameter of the right and left pulmonary arteries is evaluated again about one year after surgery, and after meeting the standard, radical surgery for tetralogy of Fallot can be performed. If the patient’s pulmonary annulus diameter is too small, the trans-pulmonary annulus widens the right ventricular outflow tract, or if the patient has severe right ventricular funicular stenosis with loss of postoperative pulmonary valve support, both of these conditions are prone to postoperative pulmonary valve closure insufficiency. If the patient does not tolerate this closure insufficiency in the long term, intervention for pulmonary valve insufficiency may be required. Such interventions include surgical or interventional treatment. The possibility of reintervention also exists in some patients with unacceptable postoperative stenosis or aneurysmal dilatation of the right ventricular outflow tract for various reasons. 12. What are the mortality and long-term survival rates of radical surgery for tetralogy of Fallot? The European multicenter joint clinical study showed that the operative mortality rate is 2.3%, and the long-term survival rate is over 90% in 10-20 years after surgery. In the past 10 years, Fu Wai Hospital has performed more than 4,000 cases of radical surgery for tetralogy of Fallot, and the operative mortality rate is around 2.0%. There is a lack of data on the long-term survival rate. 13.What are the surgical risks of radical surgery for tetralogy of Fallot? After radical surgery for tetralogy of Fallot, the following risks may occur: low cardiac output syndrome; systemic capillary leak syndrome, which is characterized by severe edema and massive thoracoabdominal leakage; residual septal shunt; pulmonary regurgitation; residual obstruction of the right ventricular outflow tract, which is characterized by stenosis of the right and left pulmonary arteries, main pulmonary artery, pulmonary orifice, subvalvular or right ventricular outflow tract; right ventricular dilatation and aneurysmal changes of the right ventricular outflow tract. tricuspid regurgitation; arrhythmias, including complete AV block, ventricular arrhythmias, prolonged QRS intervals, and supraventricular arrhythmias. 14.What issues need attention after radical surgery for tetralogy of Fallot? A special issue that needs attention is to check the ECG regularly to observe the presence of ventricular arrhythmias and progressive widening of QRS waves. Because of the septal patch and septal fibrosis resulting in septal dyskinesia, the contractility of the left ventricular myocardium is weakened in the long term after radical surgery for tetralogy of Fallot, and the anterior and posterior loads are higher than those of normal peers, so school-age children should avoid strenuous physical activities and adults should avoid heavy body work.