A nonfluoroscopic electroanatomical cardiac mapping system (CARTO) integrates anatomical and electrophysiological information to reconstruct a three-dimensional activation map. Information from the CARTO system helps to reveal the mechanism and perform successful ablation in scar re-entry ventricular tachycardia after cardiac surgery. Three-dimensional activation and propagation mapping was performed in a patient with ventricular tachycardia after surgical correction of a double outlet right ventricle. The ventricular tachycardia appeared in two morphologies and were refractory to antiarrhythmic medication including amiodarone. Both ventricular tachycardias were re-entered using the ventriculotomy scar but rotated in different directions. Successful radiofrequency ablation was performed by creating a line of conduction block from the pulmonic valve to the ventriculotomy scar using entrainment mapping and the ablation lesion tagging technique. The CARTO system is useful in mapping and guiding the ablation of complex ventricular tachycardia after surgical correction in congenital heart disease