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.
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.
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.
Table 78-1 Causes of Syncope in Children and Adolescents ||Download (.pdf)
Table 78-1 Causes of Syncope in Children and Adolescents
Neurally mediated: most common cause of syncope in children
Vasovagal: <1 min duration, prolonged standing, emotional upset, warning signs
Orthostatic: light-headedness with standing may precede; due to hypovolemia
Situational: urination, defecation, coughing, and swallowing may precipitate familial dysautonomia
Cardiac dysrhythmias: events that usually start and end abruptly
Prolonged Q-T syndrome
Supraventricular tachycardia / Wolff-Parkinson-White syndrome
Sick sinus syndrome: associated with prior heart surgery
Atrioventricular block: most common in children with congenital heart disease
Structural cardiac disease:
Hypertrophic cardiomyopathy: commonly exertional syncope; infants present with congestive heart failure and cyanosis
Dilated cardiomyopathy: idiopathic, postmyocarditis, or congenital
Congenital heart disease
Valvular diseases: aortic stenosis often congenital; Ebstein malformation; mitral valve prolapse (associated with syncope but NOT increased risk of sudden death)
Arrhythmogenic right ventricular dysplasia
Pulmonary hypertension: dyspnea on exertion, exercise intolerance, shortness of breath
Coronary artery abnormalities: aberrant left main artery causing external compression during physical exercise
|Medications and drugs: antihypertensives, tricyclic antidepressants, cocaine, diuretics, antidysrhythmics|
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.
Table 78-2 Risk Factors for a Serious Cause of Syncope