Interventional catheterization is an alternative to surgery for some congenital heart defects. For other malformations, the surgeon and the interventionist will join in an effort to obtain an optimal result: the typical example is pulmonary atresia with VSD and aortopulmonary collaterals. In other cases, the cardiologist may be called upon to intervene with catheter techniques to correct sequelae or residual lesions after surgical correction, avoiding redo surgery. Most often, the task consists of opening stenoses by balloon dilatation and/or stenting the main targets being pulmonary artery branch stenoses, venous obstructions after Mustard procedure, and recoarctations. Whereas simple balloon dilatation of recoarctation often brings good results, stents are often needed to obtain optimal results in pulmonary branch stenoses. Stenting of pulmonary veins has been disappointing. Closing unwanted vessels and defects is another task for the interventional cardiologist after cardiac surgery. Here, the most frequent procedure is closing aortopulmonary collaterals in pulmonary atresia and VSD after corrective surgery. Advantages and limitations of these procedures are discussed.