Tetralogy of Fallot Graphic (IMAGE) University of California - San Diego Caption Tetralogy of Fallot is one of the most common congenital heart diseases (or CHD), and makes up about 20% of CHD cases. Patients require surgery before six months of age, often followed by a second intervention during the toddler years. Credit University of California San Diego Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.