In children, sudden death related to ventricular arrhythmias occurs virtually always in a patient with an abnormal heart. Therefore, children with ventricular tachycardia should be thoroughly investigated by anatomic cardiac catheterization and possibly electrophysiologic study. Sudden death may occur in a patient who had been relatively asymptomatic. This especially occurs in patients after repair of congenital heart disease. The patient may also never have had documented ventricular tachycardia, although most have had at least premature ventricular complexes on a Holter monitor recording. Finally, sudden death related to ventricular arrhythmias can often be prevented with vigorous medical and surgical therapy.