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Syncope, also known as fainting or sudden loss of consciousness, is usually a benign process with many causes, but it can be a symptom of serious cardiac disease and can predispose to sudden death. Assessing syncope in children is challenging due to the variability of symptoms and lack of a gold standard for evaluation. Sudden cardiac death includes just those causes that directly relate to cardiovascular dysfunction. Although the main focus of this chapter is syncope and sudden death due to cardiovascular causes, other causes of sudden death (neurologic, respiratory, and traumatic) are also discussed.


Syncope is a presenting symptom in 0.05% of pediatric visits1 and 6% of hospital admissions2 and is more common in adolescents than in younger children. Between 20% and 50% of adolescents experience at least one episode of syncope.2 Only 25% of all patients referred to a cardiology or neurology specialty clinic for the evaluation of syncope are ultimately diagnosed with a serious illness.3 The most common type of benign syncope is neurally mediated (vasovagal) syncope.1 Therefore, prior syncopal events are not always associated with an increased risk of sudden death.4

Sudden Death

There is a difference between sudden unexpected death and sudden cardiac death, because the first can have many causes, such as a seizure, asthma, or toxic ingestion. Sudden cardiac death includes just those events that directly relate to cardiovascular dysfunction. Sudden unexpected death in children accounts for 2.3% of all deaths, or 1.3 cases per 100,000 patient-years.5 Sudden cardiac death comprises approximately one third of these deaths, or about 600 deaths per year in the U.S. Excluding trauma, sudden cardiac death is the most common cause of sports-related death in young athletes.6 Sports most frequently associated with sudden death are basketball, football, and track events.6 The greatest risk for sudden cardiac death is in patients with congenital or acquired structural cardiac disease, including those with congenital heart disease who have undergone corrective surgery. The most frequent causes of sudden cardiac death in children are listed in Table 140-1.7 Hypertrophic cardiomyopathy and myocarditis are the most common causes of sudden cardiac death in adolescents without known cardiac disease.5,7 Sudden cardiac death is usually an unexpected, unwitnessed, terminal event. When resuscitation is started rapidly in patients whose cardiac arrest is witnessed, the likelihood of survival is much greater, approaching 25%. Witnesses may be able to describe prodromal symptoms to aid in determining the cause of the event.8

Table 140-1 Predisposing Factors for Sudden Cardiac Death in Children

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