Tetralogy of Fallot is one of the most common congenital heart defects in children. The condition results in low levels of oxygen in the blood, which can cause the skin to appear blue (cyanosis). Tetralogy of Fallot involves four heart malfunctions that occur together: pulmonary stenosis (narrowing of the heart’s pulmonary valve), a ventricular septal defect, an overriding aorta (a defective connection between the aorta and the heart) and right ventricular hypertrophy (thickening of the ventricle wall). Tetralogy of Fallot is commonly repaired in early childhood.

The most common complication in adult congenital heart patients is severe pulmonary valve regurgitation (reverse blood flow), which can require surgical repair. In adult patients, heart rhythm disorders and abnormal heart function may also occur as a result of childhood tetralogy of Fallot.