Tetralogy of Fallot (Year of the Zebra)

What is Tetralogy of Fallot? Tetralogy of Fallot (TOF) is a congenital heart condition characterized by four heart abnormalities—stenosis in the right ventricular outflow tract, right ventricular hypertrophy, ventricular septal defect, and aortic override of septal defect. Together, these can cause cyanosis in the newborn.