Tetralogy of Fallot or TOF is a common congenital heart disease with 4 typical anatomical defects in the heart and the circulatory system. Here is a primer.
Congenital heart disease
Atrial Septal defect or ASD is a form of congenital heart disease where there is an abnormal hole (opening) between two upper chambers of heart. This video explains the basics.
Ventricular Septal Defect or VSD is the commonest form of congenital heart disease. Here is a primer.