Chapter 78. Syncope and Sudden Death in Children and Adolescents

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.

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.

No specific historical or clinical features reliably distinguish between vasovagal syncope and other causes. However, a thorough history and physical examination can help to arouse or allay suspicion of serious causes. The most important step in evaluation of children with syncope is a detailed history, including a thorough description of the event, associated symptoms, circumstances, medications, drugs, intake, and intercurrent illness. Syncope during exercise suggests a more serious cause. Many of the diseases that cause syncope also cause sudden death in children. Approximately 25% of children who suffer sudden death have a history of syncope. If witnesses note that the patient appeared lifeless or cardiopulmonary resuscitation was performed, a search for serious pathologic conditions must be undertaken.

The physical examination includes complete cardiovascular (heart sounds, murmurs, rhythm, and the character of pulses), neurologic, and pulmonary examinations. Abnormalities found on examination warrant further workup. Tests should be directed by the history: a classic story for vasovagal syncope with a normal physical examination requires no further testing. Palpitations or exertional syncope require ECG evaluation for potential arrhythmias. Sudden collapse, especially during exercise suggests structural abnormalities, particularly when associated with a murmur on physical examination. ECG, chest radiography, and echocardiography should be considered in this setting. Syncope associated with chest pain may require cardiac troponins as part of the evaluation to rule out ischemic heart disease (eg, aberrant left coronary artery). Electrolytes, thyroid studies, and urine pregnancy testing or drug screen should be considered in the appropriate clinical setting.

1. Obtain an electrocardiogram (ECG) in all patients except those with an unquestionable vasovagal episode.

2. Consider an echocardiogram for patients with known or suspected cardiac disease. If an echocardiogram is not immediately available, the urgency for obtaining the study should be determined in consultation with a cardiologist.

3. If no clear cause is found, the child may be discharged to be further evaluated and followed by the primary care physician unless there are cardiac risk factors or exercise-induced symptoms for which referral to a cardiologist is warranted.

4. Patients with a normal ECG but a history suggesting a dysrhythmia are candidates for outpatient monitoring and cardiac workup.

5. Children with documented dysrhythmias should be admitted. All children admitted for syncope should undergo cardiac monitoring. Children who are survivors of sudden cardiac arrest should be admitted to a pediatric intensive care unit.