[Cardiac syncope in children].

Syncope is a frequent and usually benign problem in childhood. Vasovagal syncope is the most likely etiology and is well recognized. However, syncope can herald a potentially lethal problem, so that routine evaluation including a 12-lead standard ECG should be performed in all cases. Worrying features requiring further investigations include syncope during emotion or exercise, history of familial syncope or sudden death in the young, and any abnormality on clinical exam or ECG tracings. Structural cardiac abnormalities that may cause syncope include cardiac obstructions, pulmonary hypertension, and myocardiopathy. Children with congenital heart disease who experienced syncope should always be referred to a specialist. Primary arrhythmias which are easily diagnosed on ECG are complete atrio-ventricular block and Wolff-Parkinson-White syndrome. "Channelopathies" such as the long OT syndrome and catecholaminergic ventricular tachycardia are increasingly recognized in children, carry a high risk of sudden death and deserve a complete work up, including familial screening and lifelong treatment with beta-blockers.