Underlying diseases in syncope of children in China.

Background: Syncope accounts for about 1-2% of emergency department visits, but the etiology in many patients with syncope is unclear. Recently, with the use of the head-up tilt test (HUT), the number of patients with unexplained syncope (UPS) has been decreasing; however, the spectrum of underlying diseases of syncope in children is unclear. This retrospective study aimed to analyze the spectrum of underlying diseases in children with syncope. Material/Methods: This multi-center clinical study consisted of 888 children (417 males, 471 females, aged 5-18 yrs, median age 12.0 +/- 3.0 yrs) with syncope who came from Beijing city, Hunan province, Hubei province and Shanghai from August 1999 to March 2009. The clinical and laboratory data of children were studied and the spectrum of underlying diseases in children with syncope was analyzed. Results: In 888 children with syncope, 175 (19.7%) had vasovagal syncope (VVS) with vasoinhibitory response, 35 (3.9%) had VVS with cardioinhibitory response, 73 (8.2%) had VVS with mixed response, 286 (32.2%) had postural orthostatic tachycardia syndrome (POTS), 19 (2.1%) had orthostatic hypotension, 7 (0.9%) had situational syncope, 13 (1.5%) had cardiogenic syncope, and 280 (31.5%) had unexplained syncope. Conclusions: The data suggest that neurally-mediated syncope was the most common cause in children with syncope. POTS and VVS were the most common hemodynamic patterns of neurally-mediated syncope.