Since diagnostic cardiac catheterization in children with congenital heart disease was first reported in 1947, echocardiography has been used as a non-invasive diagnostic tool in congenital heart disease, resulting in a decrease in diagnostic cardiac catheterizations. However, the total number of cardiac catheterizations remained at a steady level until the mid-1980s and has since increased progressively. This is a result of the introduction of interventional transcatheter techniques to improve or correct congenital heart malformations. Since the first description of balloon atrial septostomy, the range of indications for such techniques has steadily increased, particularly in the past 15 years. 'Deep' sedation or general anaesthesia is essential for the conduct of cardiac catheterization in children, particularly in the younger age group.