Syncope is a frequent complaint encountered by pediatricians and pediatric cardiologists alike. Understanding the mechanism, typical presentation, common causes, and warning signs of serious diseases are essential for the practitioner to carefully formulate a focused differential diagnosis and plan of treatment. Syncope is a transient and abrupt loss of consciousness and postural tone, resulting from a decrease in cerebral blood flow, followed by spontaneous recovery after a few seconds. A typical presentation in an older child is loss of consciousness that occurs when the patient is upright, either sitting or standing. There is a characteristic early prodrome of dizziness, nausea, diaphoresis, and pallor before the syncopal event. The most common biological mechanism for the decrease in cerebral blood flow is a transient disturbance of the normal reflexive mechanisms of the autonomic nervous system in regulating peripheral vascular resistance, blood pressure, and heart rate.1
The incidence of syncopal events in children and adolescents was approximately 71 per 100,000 (0.07%) and 126 per 100,000 (0.126%), respectively, during two 5-year observational periods.2 There was a higher incidence in girls compared with boys during both periods. Syncope has a bimodal incidence in toddlers and adolescents, with the peak incidence between ages 15 and 19 years. This study also concluded that mortality and long-time survival of patients who experienced syncope were no different from the general population. Up to one-third of the population will experience syncope in their lifetime, and an estimated 15% will experience syncope before age 21 years.3 Although syncope is common and usually benign in etiology, it frequently causes stress and anxiety for patients and family members about potential cardiovascular disease and possible sudden cardiac death.
Differential Diagnosis and Causes
The most commonly diagnosed cause of syncope in children is neurocardiogenic syncope, accounting for up to 80% of cases.4 The presentation of neurocardiogenic syncope can be quite variable. It tends to have three distinct stages that consist of a prodrome (usually dizziness, nausea, diaphoresis, pallor, or visual changes), followed by sudden loss of consciousness, and ending with rapid recovery (postictal states are rare).5
There are many different causes of syncope and an important task of the pediatrician is to differentiate the benign types of syncope from those that are associated with increased risk for sudden cardiac death. Table 1 lists the various benign and serious pathologic causes for syncope in children. Table 1 only serves to illustrate the many causes of syncope in children and is not intended to be comprehensive.
Various Causes of Syncope
It is crucial to obtain a careful patient history; details surrounding and precipitating the syncopal event often add important clues to a potential etiology and diagnosis. Examples would be a patient describing the classic prodrome of dizziness, nausea, diaphoresis, pallor, and visual changes typical for neurocardiogenic syncope. Inciting triggers preceding their syncopal events such as micturition or psychological stress would also suggest reflexive or triggered neurocardiogenic syncope. Syncope precipitated by loud noise (telephone or alarm clock), swimming in cold water, or extreme emotion are of concern for possible long QT syndrome (LQTS). Associated cardiovascular complaints such as chest pain, palpitations, tachycardia, and cyanosis should always raise concern for serious pathologic cause as they are not typical for the benign causes of syncope. Many serious cardiac causes of syncope have few warning symptoms preceding loss of consciousness and acute collapse (often with exercise). It should be noted that syncope associated with exercise is not always pathologic and is frequently seen after sports events such as marathons. This is thought to be related to vasodilation and shifting autonomic states. In fact, the sports medicine literature uses the term “exercise-associated collapse” to describe athletes who are unable to stand or walk unaided as a result of light-headedness, faintness, dizziness, or syncope.6 Syncope that occurs during exercise and at peak exercise tends to be more ominous than syncope in the post-exertional state.7 The patient's medical, social, and family history are also essential. A thorough social history may lead to drug or alcohol intoxication as the offending cause. A detailed family history should particularly look for incidents of sudden or unexplained deaths. Several known cardiac causes of syncope have a familial or genetic origin. An example could be detailed family history uncovering early heart attacks suggesting cardiomyopathy or arrhythmia syndromes. A family history of bilateral hearing loss may suggest a form of LQTS (eg, Jervell and Lange-Nielsen Syndrome).
In combination with a detailed history, a comprehensive physical examination should be performed. Although physical examinations in many cases are unremarkable, positive results can narrow the differential diagnosis or even establish an etiology of the patient's syncope. Significant variations in orthostatic vital signs would suggest that orthostatic syndromes are the cause of a patient's syncope. A febrile and toxic-appearing child may suggest myocarditis as the etiology for their syncope. Furthermore, a systolic ejection murmur that increases with intensity during Valsalva maneuver is classic for dynamic left ventricular outflow tract obstruction in hypertrophic cardiomyopathy. Gallop rhythms that are auscultated in patients can indicate congestive heart failure with underlying cardiomyopathies. A loud P2 component of the second heart sound is classic for idiopathic pulmonary artery hypertension.
Knowing and understanding the various causes of pediatric syncope allows for identifying “red flags” that may signal a potentially serious condition. This knowledge base is essential for providers to accurately distinguish between the more common benign causes and many of the serious pathologic causes of syncope in children.
Family History and Testing
Along with a detailed history and physical examination, several medical tests can be performed to identify or rule out a specific cause of a patient's syncope. These tests are typically cardiovascular studies and all have variable sensitivity and specificity.
An electrocardiogram (ECG) is essential for the evaluation of syncope. It is one of the simplest and most accessible tests for any practitioner. An ECG allows for identification of normal and abnormal electrical events of the heart in a 10-second period. The screening combination of detailed history, comprehensive physical examination, and ECG should identify the vast majority of patients with a serious underlying cardiac condition. Supporting this position, a study of 480 children with syncope demonstrated that an abnormal history, physical examination, or ECG identified 21 of the 22 patients with a cardiac cause of syncope.8 With no alarming event history, a negative family history, a normal physical examination, and normal ECG, most patients and families can be given reassurance without further testing. Also, a normal ECG can rule out several serious cardiovascular causes for syncope, such as heart block, Wolff-Parkinson-White syndrome, LQTS, and Brugada syndrome.
The routine use of other diagnostic tests such as echocardiography, ambulatory ECG (event or Holter monitoring), tilt-table tests, and exercise stress tests is frequently of low diagnostic yield and adds to health care costs.9 Also, the indiscriminate use of these tests may cause undue anxiety and stress for both the patient and family. The use of these tests should be made in a thoughtful manner and frequently in coordination with a pediatric cardiologist. Recent uses of diagnostic pathways or decision trees in the management of pediatric syncope have aimed specifically at reducing unnecessary testing and referrals while still identifying important and serious causes of syncope.3
An echocardiogram is a diagnostic study of the heart that uses ultrasound to produce real-time moving images of the cardiac structures and hemodynamic events. Echocardiograms can be useful in select patients with abnormal physical examination results, abnormal ECGs, positive family history, or concerning histories. In the aforementioned study by Ritter et al.,8 none of the patients diagnosed with a cardiac cause of syncope had echocardiograms contributing to their diagnosis. The authors concluded that in the absence of a positive screen result, an echocardiogram does not contribute to the evaluation of syncope in children. That being said, an echocardiogram is an outstanding tool for detecting structural heart disease such as left ventricular outflow tract obstruction, hypertrophic cardiomyopathy, dilated cardiomyopathy, cardiac tumors, and coronary artery anomalies. It is also helpful (although not highly sensitive) in detecting patients who have idiopathic pulmonary artery hypertension.
Ambulatory ECG uses a wide array of wearable devices for the purposes of arrhythmia detection. Patients frequently wear these devices outside of the hospital and clinic and return them for interpretation after a specified period of testing. They are typically classified as either continuous recorders (eg, Holter monitors), which are typically used for 24 to 48 hours, or intermittent recorders (event monitors), which may be used for long periods of time to provide shorter, periodic recordings. In a study of 495 event monitors, these types of devices were found useful in the evaluation of children and adolescents with palpitations but not with isolated chest pain, syncope, or presyncope.10 With advancement of solid-state digital technology, implantable loop recorders with batteries that may last for up to 3 years are also now widely available.
Tilt-table testing is a simple and noninvasive procedure in which a patient is securely strapped to a table while supine. The table is designed for and has a mechanism to tilt the patient toward the vertical orientation (as if standing). Most of the time, the patient is suspended at an angle of 60 to 80 degrees. Patients have cardiorespiratory monitors on during the test. Pharmacologic agents such as isoproterenol can also be given depending on the clinical scenario. Tilt-table tests are occasionally recommended as a means of provoking neurocardiogenic syncope in susceptible patients to confirm the diagnosis. However, tilt-table testing has limited specificity: up to 40% of adolescents with no previous history of syncope may have a positive result on tilt-table test.1 In addition, tilt-table tests have poor sensitivity (65%–75%) and reproducibility (50%–87%), further limiting their usefulness and adding to their dubious record.11
Exercise stress testing typically employs a treadmill (or cycle ergometer), ECG, and blood pressure monitors. It is sometimes called a treadmill test or exercise test. Fundamentally, the test is meant to monitor for abnormal (often subtle) changes in symptoms, vital signs, or ECG while a patient is put through a graded physical challenge. It also serves as a tool to assess functional capacity for recreational, athletic, and vocational activities or to evaluate prognosis, including both baseline and serial testing measurements. Exercise stress tests should be reserved for the subset of patients who have exertional syncope or exertional symptoms. The test has some important limitations, as young children or toddlers may not be cooperative enough to perform a quality study. Also, the test is highly dependent on patient exercise effort, so unmotivated patients may lead to inconclusive results. Some of the serious cardiac conditions that may be elucidated from an exercise stress test are catecholaminergic polymorphic ventricular tachycardia and LQTS.
Treatment and Therapy
Treatment and therapy for syncope are dependent on the cause. As most cases of syncope in children and adolescents are benign in cause, the primary task of the pediatrician or pediatric cardiologist is reassurance and education to the patient and family. The education should be focused on preventing or limiting the severity of future episodes. Encouraging adequate oral fluid and salt intake can improve symptoms in most patients.12 Understanding the settings that lead to individual syncopal events also aids in tailoring specific recommendations. Patients who experience prodromal symptoms should be educated to recognize the symptoms and instructed to assume a supine position at the onset. This may help in both aborting the syncopal event and in limiting bodily injury. A cross-country runner with exercise-associated collapse might consider using post-exertional postural techniques to prevent venous blood pooling. Counter-pressure maneuvers or isometric extremity contractions are commonly employed techniques. These may include gripping fingers into a fist, tensing of the arms, crossing the arms or the legs or squeezing the thighs together, and toe raises.
Medications are rarely needed for treatment of syncope. There are published reports of using midodrine, fludrocortisone, beta-blockers, selective-serotonin reuptake inhibitors, methylphenidate, and epoetin alfa.12 Treatment with medications for benign forms of syncope is generally not routine and is reserved for patients with frequent or severe symptoms and for patients who fail conservative management. Fortunately for most patients, even those who are extremely symptomatic, there is typically improvement of symptoms with time. Other treatment modalities such as biofeedback, behavioral modification, and cardiac pacing for malignant forms of neurocardiogenic syncope have been reported.13,14
Patients with benign causes of syncope should still have a plan for follow-up. This provides a method of insuring that treatment recommendations are followed and screening for the few patients who may need empiric pharmacologic treatment or pediatric cardiology referral.
Syncope is a common presenting complaint in children and adolescents. The vast majority of cases are benign in etiology. With careful screening by detailed patient history, comprehensive physical examination, and ECG testing, a significant majority of patients with serious underlying cardiac conditions will be identified. The routine use of echocardiography, ambulatory ECG, tilt-table tests, and exercise stress tests are expensive and frequently of low diagnostic yield. With benign forms of syncope, patient reassurance and education should be the first-line treatment.
- McLeod KA. Syncope in childhood. Arch Dis Child. 2003;88(4):350–353. doi:10.1136/adc.88.4.350 [CrossRef]
- Driscoll D, Jacobsen S, Porter CJ, et al. Syncope in children and adolescents. J Am Coll Cardiol. 1997;29:1039–1045. doi:10.1016/S0735-1097(97)00020-X [CrossRef]
- Friedman KG, Alexander ME. Chest pain and syncope in children: a practical approach to the diagnosis of cardiac disease. J Pediatr. 2013;163(3):896–901.e1–3. doi:10.1016/j.jpeds.2013.05.001 [CrossRef]
- Massin MM, Bourguignont A, Coremans C, Comte L, Lepage P, Gerard P. Syncope in pediatric patients presenting to an emergency department. J Pediatr. 2004;145:223–228. doi:10.1016/j.jpeds.2004.01.048 [CrossRef]
- Grubb BP. Neurocardiogenic syncope and related disorders of orthostatic intolerance. Circulation. 2005;111(22):2997–3006. doi:10.1161/CIRCULATIONAHA.104.482018 [CrossRef]
- Roberts WO. Exercise-associated collapse in endurance events: a classification system. Physician Sportsmed. 1989;17(5):49–55.
- O'Connor FG, Oriscello RG, Levine BD. Exercise-related syncope in the young athlete: reassurance, restriction or referral?Am Fam Physician. 1999;60(7):2001–2018.
- Ritter S, Tani LY, Etheridge SP, Williams RV, Craig JE, Minich LL. What is the yield of screening echocardiography in pediatric syncope?Pediatrics. 2000;105(5):E58. doi:10.1542/peds.105.5.e58 [CrossRef]
- Steinberg LA, Knilans TK. Syncope in children: diagnostic tests have a high cost and low yield. J Pediatr. 2005;146(3):355–358. doi:10.1016/j.jpeds.2004.10.039 [CrossRef]
- Saarel EV, Stefanelli CB, Fischbach PS, Serwer GA, Rosenthal A, Dick M 2nd, . Transtelephonic electrocardiographic monitors for evaluation of children and adolescents with suspected arrhythmias. Pediatrics. 2004;113(2):248–251. doi:10.1542/peds.113.2.248 [CrossRef]
- Kapoor WN, Smith MA, Miller NL. Upright tilt testing in evaluating syncope: a comprehensive literature review. Am J Med. 1994;97:78–88. doi:10.1016/0002-9343(94)90051-5 [CrossRef]
- Boehm KE, Morris EJ, Kip KT, Karas B, Grubb BP. Diagnosis and management of neurally mediated syncope and related conditions in adolescents. J Adolesc Health. 2001;28:2–9. doi:10.1016/S1054-139X(00)00153-1 [CrossRef]
- Smith ML. Mechanisms of vasovagal syncope: relevance to postflight orthostatic intolerance. J Clin Pharmacol. 1994;34:460–465. doi:10.1002/j.1552-4604.1994.tb04987.x [CrossRef]
- Connolly SJ, Sheldon R, Roberts RS, Gent M. The North American vasovagal pacemaker study: a randomized trial of permanent cardiac pacing for the prevention of vasovagal syncope. J Am Coll Cardiol. 1999;33:16–20. doi:10.1016/S0735-1097(98)00549-X [CrossRef]
Various Causes of Syncope
Reflexive or triggered syncope
Micturition, stretching, coughing, psychologic stress (eg, visualizing blood or needles)
Postural orthostatic tachycardia syndrome
Spinal cord injuries
Anxiety or panic attacks
Factitious or conversion disorders
Environmental or exposures
Intoxication or drug use
Left ventricular outflow tract obstruction
Idiopathic pulmonary artery hypertension
Coronary artery abnormalities
Long QT syndrome
Arrhythmogenic right ventricular dysplasia
Catecholaminergic polymorphic ventricular tachycardia
Congenital/acquired heart block
Left ventricular noncompaction