Accompanying advances in the treatment of arrhythmias in adults, there have been remarkable advances in the treatment of arrhythmias in children and congenital heart disease. Wolff–Parkinson–White syndrome can now be safely ablated in children. Patients with severe congenital heart disease also are now surviving into adulthood, leading to new problems of arrhythmias and sudden death. Recently, a conduit puncture and ablation technique was developed for treating arrhythmias after Fontan surgery that has resulted in improved outcomes.