[Cardiac syncope in children].

Syncope is a frequent problem in childhood; generally, it is an isolated event and the common causes are benign. However, in some circumstances, syncope can herald a potentially lethal problem, especially when occurring during exercise. Routine evaluation includes history, physical examination and a 12-lead standard ECG should be performed in all cases. Worrying features which should be an indication for further investigation include syncope during exercise, collapse in a swimming pool, history of familial sudden death, and abnormalities on clinical exam or ECG. Structural cardiac abnormalities that may cause syncope and sudden death include aortic stenosis, hypertrophic cardiomyopathy and coronary malformations. All children with unrepaired or repaired congenital heart disease who experienced a syncope should be referred to a specialist. Primary arrhythmias that are easily diagnosed on ECG are the long QT syndrome, complete atrio-ventricular block and Wolff-Parkinson-White syndrome; ST elevation in V1-V3 may reveal a Brugada syndrome. Another arrhythmia which is known to be potentially fatal if undiagnosed is the catecholaminergic ventricular tachycardia; the baseline ECG is normal but the arrhythmia is easily reproduced during exercise testing. Finally, vasovagal syncope is the most likely cause of syncope in the young and it usually easily recognized.