Paroxysmal Complete Atrioventricular Block: A Rare Cause of Syncope in Children.

Paroxysmal atrioventricular block (PAVB) is a rare cause of syncope, mostly reported in adults. In the present study, a child with recurrent syncope due to PAVB is reported. A 12-year old boy was admitted due to syncope. Some syncopal episodes were consistent with vasovagal syncope, while others had atypical features. Electrocardiography, echocardiography and 24-hour electrocardiography monitoring were normal. Head-up tilt table test revealed mixed type vasovagal syncope. With beta-blocker treatment, the frequency of syncopal episodes decreased; however, the episodes with atypical features continued. Intracardiac electrophysiological study was normal, but repeated external loop recorder monitoring revealed transient AVB during a syncopal episode. In children with syncope with atypical features, PAVB should be kept in mind. Repeated external loop recorder monitoring may be useful in the diagnosis of such seldom seen arrhythmic causes.