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Syncope is more common in adolescents than younger children. Up to 50% of adolescents experience at least 1 syncopal episode. This condition is usually transient and usually self-limited, but can be a symptom of serious cardiac disease.
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Sudden, unexpected death in children comprises 2.3% of all pediatric deaths of which sudden cardiac death makes up about one-third. Except for trauma, sudden cardiac death is the most common cause of sports-related deaths, particularly in basketball, football, and track. Hypertrophic cardiomyopathy is the most common cause of sudden cardiac death in adolescents without known cardiac disease. Other causes of sudden cardiac death in children include myocarditis, congenital heart disease, and conduction disturbances.
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Syncope is the sudden onset of falling accompanied by a brief episode of loss of consciousness. Involuntary motor movements may occur with all types of syncopal episodes but are most common with seizures. Two-thirds of children experience light-headedness or dizziness before the episode (“presyncopal” symptoms). Table 78-1 lists the most common causes of syncope by category.
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Neurally mediated syncope is the most common cause in children and includes vasovagal, vasodepressor, neurocardiogenic, reflex syncope, and simple fainting. This type of syncope is usually preceded by sensations of nausea, warmth, or light-headedness with a gradual visual grayout. Cardiac syncope occurs when there is an interruption of cardiac output from an intrinsic problem such as tachydysrhythmia, bradydysrhythmia, outflow obstruction, and myocardial dysfunction. Syncope resulting from cardiac causes usually begins and ends abruptly and may be associated with chest pain, palpitations, or shortness of breath. Risk factors associated with serious causes of syncope are presented in Table 78-2. Events easily mistaken for syncope are presented in Table 78-3 in addition to common associated symptoms.
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