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Causes of syncope in children and adolescents

Jack C Salerno, MD
Section Editors
George A Woodward, MD
John K Triedman, MD
Deputy Editor
James F Wiley, II, MD, MPH


This topic will review the serious and benign causes of syncope. A discussion of the emergent evaluation and algorithmic approach to children and adolescents with syncope is presented separately (algorithm 1). The evaluation of adults with syncope is also discussed elsewhere. (See "Emergent evaluation of syncope in children and adolescents" and "Syncope in adults: Clinical manifestations and diagnostic evaluation".)


Syncope is a sudden, brief loss of consciousness associated with loss of postural tone from which recovery is spontaneous [1]. Up to 15 percent of children experience a syncopal episode prior to the end of adolescence [2,3].

Although the etiology of syncopal events in children is most often benign, syncope can also occur as the result of more serious (usually cardiac) disease with the potential for sudden death. The vast majority of cases of syncope in the pediatric age group represent benign alterations in vasomotor tone [4,5]. Life-threatening causes of syncope generally have a cardiac etiology (table 1).


Life-threatening cardiac conditions cause syncope as the result of an abrupt decrease in cardiac output, either from an arrhythmia or related to structural heart disease [6]. Arrhythmias are typically tachyarrhythmias. In children, syncope caused by isolated bradycardia (ie, complete AV block) is uncommon [7]. (See "Bradycardia in children", section on 'Clinical presentation'.)

Primary electrical disturbances can occur in patients with structurally normal hearts. These arrhythmias may be related to exogenous factors (ie, a metabolic disturbance or drug ingestion) or an inherited electrophysiologic abnormality (ie, congenital long QT syndrome). Arrhythmias may also develop as the result of structural heart disease, such as myocarditis or repaired congenital heart disease. Finally, syncope can occur in conditions such as aortic stenosis and hypertrophic cardiomyopathy (HCM) as the result of left ventricular outflow tract obstruction and compromised systemic blood flow, particularly during exercise.

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Literature review current through: Oct 2017. | This topic last updated: May 31, 2017.
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