Whether diagnosed before birth or suspected in a newborn, congenital heart diseases rapidly require an evaluation by the pediatric cardiologist. The role of the pediatric cardiologist is threefold: 1) to realize a careful anatomical examination using color Doppler echocardiography; 2) in many cases to perform a palliative or curative therapeutic act based upon interventional catheterization, such as Rashkind atrioseptotomy or percutaneous balloon valvuloplasty; and 3) whenever necessary, to take a rapid decision of cardiac surgery in concert with the cardiac surgeon, and to prepare the child for surgery.