Insufficient myocardial protection is considered one of the main causes of death in the correction of TOF. Comorbidities
There are many comorbid conditions that can occur with TOF that may exacerbate the condition. Often, TOF can present with low birth weight and prematurity. In both of these cases, mortality and morbidity were both seen to increase. Differences in right atrial and ventricular mechanics and liver stiffness was also observed in adults with repaired TOF, as well as pulmonary atresia and persistent pulmonary stenosis. In patients with pulmonary atresia, there is complete failure of forward flow from the right ventricle to the pulmonary arterial vasculature. As such, pulmonary blood flow is entirely dependent on shunting from the systemic circulation, typically through a patent ductus arteriosus. The pathophysiology of TOF together with pulmonary arteriosus is uniquely attributable to defects of the pulmonary arteries. Even after operative care, these patients remain at higher risk for pulmonary arterial stenoses and pulmonary hypertension.Danon disease, which is a rare genetic disorder, was also observed to complicate TOF. In particular, elongation of the QRS complex and a shortened PR interval. Genetic abnormalities found in TOF may lead to the earlier diagnosis of Danon disease, helping to improve prognostic outcomes. Epidemiology
The prevalence of tetralogy of Fallot is estimated to be 0.02–0.04%, which corresponds to approximately 200 to 400 cases per million live births. It accounts for 7–10% of all congenital heart abnormalities, making it the most common cyanotic heart defect.
15-month-old Eileen Saxon was the first person to receive a Blalock–Thomas–Taussig shunt. Furthermore, the Blalock-Thomas-Taussig procedure, initially the only surgical treatment available for tetralogy of Fallot, was palliative but not curative. The first total repair of tetralogy of Fallot was done by a team led by C. Walton Lillehei at the University of Minnesota in 1954 on an 11-year-old boy. Total repair on infants has had success from 1981, with research indicating that it has a comparatively low mortality rate. Today the adult TOF population continues to grow and is one of the most common congenital heart defect seen in adult outpatient clinics. : 100–101

Related disorders
The following illnesses have symptoms that are comparable to tetralogy of Fallot. For a differential diagnosis, comparisons between these disorders provides valuable knowledge. Atrial septal defects
Atrial septal defects (ASDs) are a kind of congenital heart abnormality in which a tiny opening exists between the two atria of the heart. The burden on the right side of the heart is increased as a result of these abnormalities, as is the blood flow to the lungs. This leads to excessive blood flow to the lungs and an increased workload on the right side of the heart. Another common finding associated with ASDs is right ventricular hypertrophy, also known as enlargement of the right ventricle. Ventricular septal defects
Ventricular septal defects (VSDs) are a kind of congenital heart abnormality in which one of the ventricles is missing. Two atria and one big ventricle are common in infants with congenital abnormalities.