: 153 Timing of surgery in asymptomatic patients is usually between the ages of two months to one year. : 201–2  However, in symptomatic patients showing worsening blood oxygen levels, severe tet-spells (cyanotic spells), or dependence on prostaglandins from early neonatal period (to keep the ductus arteriosus open) need to be planned fairly urgently: 201–2 Potential surgical repair complications include residual ventricular septal defect, residual outflow tract obstruction, complete atrioventricular block, arrhythmias, aneurysm of right ventricular outflow patch, and pulmonary valve insufficiency. : 59  Long-term complications most commonly include pulmonary valve regurgitation, and arrhythmias.Total repair of tetralogy of Fallot initially carried a high mortality risk, but this risk has gone down steadily over the years. Surgery is now often carried out in infants one year of age or younger with less than 5% perioperative mortality. : 205  Post surgery, most patients enjoy an active life free of symptoms. : 205  Currently, long-term survival is close to 90%. : 167  Today the adult TOF population continues to grow and is one of the most common congenital heart defects seen in adult outpatient clinics. : 100–101

Palliative surgery
Initially surgery involved forming a side to end anastomosis between the subclavian artery and the pulmonary artery -i.e. a systemic to pulmonary arterial shunt. : 57  This redirected a large portion of the partially oxygenated blood leaving the heart for the body into the lungs, increasing flow through the pulmonary circuit, and relieving symptoms.
In the famous Baltimore-Washington Study, it was reported that smoking more than one pack per day while pregnant was associated with two specific cardiac deflects, both part of TOF: pulmonary stenosis and transposition with VSD. Maternal diabetes: Maternal diabetes, diabetes Mellitus, and gestational diabetes are well-known risk factors of fetal CHD, including TOF. Maternal diabetes has been shown to increase the risk of cardiovascular deformations, namely the transposition of great arteries, one of the four deformations in TOF. Studies have also looked at whether diabetes increases the risk of malformation or poor sugar regulation and have found that sugar regulation does not significantly affect cardiac malformations. Retrospective studies have shown that diabetic mothers with good glucose control still retained the elevated CHD risk. Rubella: Rubella is characterized as mild, contagious viral disease with often unnoticed consequences. Infection with rubella during the first trimester has been seen to cause various fetal malformations, including TOF. Maternal Age: Older maternal age, especially after 35 can have various pregnancy risks due to existing co-morbidities such as hypertension, diabetes, hypothyroidism, and consanguinity. These risk factors can effect fetal development and lead to various fetal conditions such as CHD (including TOF), Down Syndrome and Autism.Embryology studies show that anterior malalignment of the aorticopulmonary septum results in the clinical combination of a ventricular septal defect (VSD), pulmonary stenosis, and an overriding aorta. : 200  Right ventricular hypertrophy develops progressively from resistance to blood flow through the right ventricular outflow tract.