No clinical or historical features reliably distinguish between vasovagal syncope and other causes. 4 However, certain historical features and a careful history and physical exam should increase an emergency physician's suspicion of a potentially serious cause ( Table 12Z-2). Particular attention should be directed to the cardiovascular exam, including palpation of the cardiac impulse, auscultation of the heart, and evaluation of the peripheral pulses. Orthostatic measurements will identify volume depletion or autonomic dysfunction. An electrocardiogram (ECG) should be obtained for nearly all children but will usually be normal. 4 Other laboratory studies are directed by the nature of the history and physical exam.
Many of the diseases that cause syncope also cause sudden death in children. A syncopal event can be the presenting symptom of these more serious illnesses. Up to 25 percent of children who suffer a sudden death have a history of at least one prior syncopal event. 6 Because syncope is a very common event, however, a syncopal event by itself is not associated with an increased risk of sudden death unless certain features are present. 5 The two most common causes of sudden cardiac death among children who do not have known cardiac disease are hypertrophic cardiomyopathy and myocarditis. 6 Primary rhythm disturbances undoubtedly are underrepresented due to the inherent difficulty in identifying these causes after death.
Among athletes who have died suddenly, however, only 10 percent had previously experienced at least one episode of syncope. 13 Even with a standard sports screening evaluation, fewer than 5 percent of athletes who subsequently die are suspected of having cardiac disease. 13 The two most common cardiac lesions associated with sudden death among athletes are hypertrophic cardiomyopathy and aberrant coronary arteries. 13 Other coronary artery abnormalities, Marfan syndrome (ruptured aortic aneurysm), valvular heart disease, myocarditis, and dilated cardiomyopathy are less common.
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