“Tetralogy of Fallot is a congenital heart defect that occurs when a baby’s heart does not form correctly during pregnancy.  It is characterized by 4 defects: a ventricular septal defect (VSD), pulmonary stenosis, an overriding aorta, and right ventricular hypertrophy.  These defects affect the way the blood flows through the heart and lungs, potentially causing symptoms like cyanosis due to low oxygen levels in the blood.  TOF is a critical congenital heart defect, and when surgery is often necessary for repair, lifelong follow ups with a cardiac doctor are essential for monitoring and managing the condition.

The causes of tetralogy of Fallot among most babies are unknown. Some babies have heart defects because of changes in their genes or chromosomes. A combination of genes and other risk factors may increase the risk for tetralogy of Fallot. These factors can include things in a mother’s environment, what she eats or drinks, or the medicines she uses.”

Center for Disease Control and Prevention – CDC (Tetralogy of Fallot | Congenital Heart Defects (CHDs) | CDC)