This article informs the general pediatrician about the diagnosis, evaluation, and treatment of teenage patients with presyncope and loss of consciousness. The focus is on distinguishing noncardiac fainting from life-threatening syncope. Current treatment strategies of vasovagal syncope and postural orthostatic tachycardia syndrome are also outlined.
Key points
- •
Syncope (fainting) is a common complaint in the teenage population.
- •
Most fainting is benign; however, it is important for health care providers to differentiate benign fainting from life-threatening syncope.
Syncope
Syncope is a sudden and brief loss of consciousness and postural tone secondary to hypoperfusion of the brain. Vasovagal syncope or neurocardiogenic syncope (fainting) results from a disturbance in the normal compensatory mechanisms of maintaining upright posture or from specific situations ( Box 1 ) that cause hypotension and sometimes bradycardia. Syncope is common in teenagers, with some studies estimating that 15% experience at least 1 episode of syncope before adulthood. Other studies estimate a higher rate, with syncope in up to 47% of adolescent girls and 24% of adolescent boys. For most patients who do faint, there is more than 1 episode (64% girls and 53% boys), but few seek medical attention. Family history often reveals relatives with near fainting or fainting. Most fainting is benign, but it is always important to distinguish simple fainting from more serious medical problems. A large prospective study of pediatric patients reported the causes and frequencies of pediatric syncope ( Box 2 ).
Pain
Fear
Emotional distress
Hair brushing
Micturition
Defecation
Cyclical postural changes
Prolonged stationary standing
Immediately after rigorous exercise
| Cause | N (%) |
|---|---|
| Autonomic-mediated reflex syncope | 346 (73.0) |
| Vasovagal syncope | 203 (42.8) |
| Postural orthostatic tachycardia syndrome | 129 (27.2) |
| Situational syncope | 8 (1.7) |
| Orthostatic hypotension | 6 (1.3) |
| Cardiac syncope | 14 (2.9) |
| Congenital long QT syndrome | 4 (0.8) |
| Sinus node dysfunction | 3 (0.7) |
| Third-degree atrioventricular block | 2 (0.4) |
| Supraventricular tachycardia | 1 (0.2) |
| Hypertrophic cardiomyopathy | 1 (0.2) |
| Dilated cardiomyopathy | 1 (0.2) |
| Primary pulmonary hypertension | 2 (0.4) |
| Neurologic syncope | 10 (2.1) |
| Seizures attack | 9 (1.9) |
| Migraine | 1 (0.2) |
| Psychiatric syncope | 11 (2.3) |
| Conversion reaction | 7 (1.4) |
| Depressive disorder | 3 (0.7) |
| School phobia | 1 (0.2) |
| Metabolic syncope | 4 (0.8) |
| Hypoglycemia | 2 (0.4) |
| Severe anemia | 1 (0.2) |
| Hyperventilation syndrome | 1 (0.2) |
| Syncope of unknown origin | 89 (18.9) |
Details about primary neurologic causes are beyond the scope of this article but should be considered when evaluating a patient with syncope. This article focuses on distinguishing benign fainting from life-threatening syncope.
Syncope
Syncope is a sudden and brief loss of consciousness and postural tone secondary to hypoperfusion of the brain. Vasovagal syncope or neurocardiogenic syncope (fainting) results from a disturbance in the normal compensatory mechanisms of maintaining upright posture or from specific situations ( Box 1 ) that cause hypotension and sometimes bradycardia. Syncope is common in teenagers, with some studies estimating that 15% experience at least 1 episode of syncope before adulthood. Other studies estimate a higher rate, with syncope in up to 47% of adolescent girls and 24% of adolescent boys. For most patients who do faint, there is more than 1 episode (64% girls and 53% boys), but few seek medical attention. Family history often reveals relatives with near fainting or fainting. Most fainting is benign, but it is always important to distinguish simple fainting from more serious medical problems. A large prospective study of pediatric patients reported the causes and frequencies of pediatric syncope ( Box 2 ).
Pain
Fear
Emotional distress
Hair brushing
Micturition
Defecation
Cyclical postural changes
Prolonged stationary standing
Immediately after rigorous exercise
| Cause | N (%) |
|---|---|
| Autonomic-mediated reflex syncope | 346 (73.0) |
| Vasovagal syncope | 203 (42.8) |
| Postural orthostatic tachycardia syndrome | 129 (27.2) |
| Situational syncope | 8 (1.7) |
| Orthostatic hypotension | 6 (1.3) |
| Cardiac syncope | 14 (2.9) |
| Congenital long QT syndrome | 4 (0.8) |
| Sinus node dysfunction | 3 (0.7) |
| Third-degree atrioventricular block | 2 (0.4) |
| Supraventricular tachycardia | 1 (0.2) |
| Hypertrophic cardiomyopathy | 1 (0.2) |
| Dilated cardiomyopathy | 1 (0.2) |
| Primary pulmonary hypertension | 2 (0.4) |
| Neurologic syncope | 10 (2.1) |
| Seizures attack | 9 (1.9) |
| Migraine | 1 (0.2) |
| Psychiatric syncope | 11 (2.3) |
| Conversion reaction | 7 (1.4) |
| Depressive disorder | 3 (0.7) |
| School phobia | 1 (0.2) |
| Metabolic syncope | 4 (0.8) |
| Hypoglycemia | 2 (0.4) |
| Severe anemia | 1 (0.2) |
| Hyperventilation syndrome | 1 (0.2) |
| Syncope of unknown origin | 89 (18.9) |
Details about primary neurologic causes are beyond the scope of this article but should be considered when evaluating a patient with syncope. This article focuses on distinguishing benign fainting from life-threatening syncope.
Vasovagal syncope
In order to maneuver from a supine or sitting position and maintain upright posture, the body goes through a normal sequence of compensatory changes that overcome gravity-induced hydraulic changes on the blood volume. The following normal sequence takes place.
- •
Initial increase in heart rate: 10 to 15 beats per minute (bpm)
- •
Activation of renin-angiotensin-aldosterone system and vasopressin
- •
Baroreceptor-mediated increase in peripheral vascular resistance
If there is a disconnect or inability to coordinate any of these mechanisms, there can be failure to maintain adequate blood return to the heart, resulting in cerebral hypoperfusion and potential loss of consciousness. Teenagers are prone to an autonomic instability in which there is an excessive decrease in blood pressure with sudden standing and almost all occasionally feel a brief light-headedness when standing from a squatting or supine position.
During vasovagal fainting, most teenagers have prodromal symptoms before loss of consciousness (feeling lightheaded or dizzy, nausea, diaphoresis, muffled hearing, or visual changes). Most of them experience these symptoms in a warm environment or during predictable situations (see Box 1 ).
Syncope games and lark
Some teenagers force themselves to pass out to obtain a high or to avoid an unwanted activity, such as a test at school. This state is achieved by hyperventilation followed by squeezing the chest or neck or performing a forceful Valsalva maneuver. The hyperventilation lowers P co 2 levels, causing a compensatory cerebral vasoconstriction. The Valsalva maneuver decreases the venous return to the heart and in combination causes sufficient decrease in cerebral perfusion to lose consciousness.
Psychogenic syncope
Psychogenic syncope was identified in 2.3% of pediatric patients in a large prospective study. These patients either fain loss of consciousness or have a concurrent psychiatric disorder (conversion disorder, anxiety disorder, or depression). The loss of consciousness occurs without hypotension or identifiable change in transcranial Doppler or electroencephalography. Patients with conversion disorder are unaware of their actions. Many of these patients are victims of abuse, and their symptoms may represent a cry for help, which should not be ignored.
Cardiac syncope
Cardiac syncope in teenagers is less common (2%–6%) than simple fainting but may represent episodes of aborted sudden death or periodic worsening of outflow tract obstruction. A high index of suspicion should be held for primary cardiac causes of loss of consciousness. A thorough history and physical with an electrocardiogram (ECG) can usually be used to determine if cardiology referral is necessary. Cardiac causes of syncope and some of the distinguishing findings are listed in Box 3 .
| Cardiac Disease | Distinguishing Findings |
|---|---|
| Hypertrophic cardiomyopathy | Syncope during exercise Family history of sudden death Systolic murmur Left ventricular hypertrophy on ECG |
| Congenital heart disease | Abnormal cardiac examination Abnormal ECG |
| Myocarditis/other cardiomyopathy | History of heart failure symptoms Abnormal ECG |
| Wolf Parkinson White | Ventricular preexcitation on ECG History of episodes of palpitations |
| Supraventricular tachycardia | History of episodes of palpitations |
| Bradycardia | Second-degree or third-degree heart block on ECG |
| Long QT syndrome | Prolonged QTc on ECG (QTc ≥440 ms in teenage boys and QTc ≥460 ms in teenage girls) Syncope during exercise or startle Family history of sudden death |
| Other channelopathies | Abnormal ECG Family history of sudden death Syncope during exercise |
| Pulmonary hypertension | Abnormal ECG with RVH Loud P2 component or abnormal S2 splitting |
Distinguishing simple fainting from cardiac syncope
Historical factors that are most helpful in distinguishing vasovagal from cardiac syncope are sudden loss of consciousness during exercise or while supine. Table 1 shows a list of predictors of cardiac syncope in children and adolescents.
| Clinical Feature | Cardiac Syncope (n = 31) | Vasovagal Syncope (n = 55) | P -Value |
|---|---|---|---|
| Age | 8.5 ± 4.2 | 11.6 ± 2.6 | .001 |
| Sex (male/female) | 15/16 | 21/34 | .357 |
| Course of disease (mo) | 19.4 ± 22.4 | 22.3 ± 14.2 | .566 |
| Number of episodes | 7.8 ± 17.6 | 5.0 ± 3.5 | .376 |
| Predisposing factors (%) | 20/31 (64.5) | 43/55 (78.2) | .169 |
| Persistent standing (%) | 1/31 (3.2) | 21/55 (38.2) | .002 |
| Warm and crowded place (%) | 0 | 10/55 (18.2) | — |
| Fear–pain emotion (%) | 0 | 10/55 (18.2) | — |
| Exercise (%) | 19/31 (61.3) | 8/55 (14.5) | .000 |
| Position | |||
| Standing (%) | 22/31 (71.0) | 53/55 (96.4) | .001 |
| Supine (%) | 8/31 (25.8) | 2/55 (3.6) | .002 |
| Various position (%) | 6/31 (19.4) | 2/55 (3.6) | .016 |
| With prodromal symptoms (%) | 16/31 (51.6) | 48/55 (87.3) | .000 |
| Dizziness (%) | 1/31 (3.1) | 33/55 (60.0) | .000 |
| Headache (%) | 2/31 (6.5) | 13/55 (23.6) | .044 |
| Chest discomfort (%) | 3/31 (9.7) | 17/55 (30.9) | .025 |
| Palpitations (%) | 6/31 (19.4) | 9/55 (15.5) | .645 |
| Sweating (%) | 5/31 (16.1) | 7/55 (12.7) | .662 |
| Pale (%) | 9/31 (29.0) | 11/55 (20.0) | .314 |
| Nausea, vomiting (%) | 4/31 (12.9) | 15/55 (27.3) | .123 |
| Blurred vision (%) | 4/31 (12.9) | 19/55 (34.5) | .130 |
| Fatigue (%) | 1/31 (3.1) | 5/55 (9.1) | .473 |
| Duration of the loss of consciousness (min) | 1.8 ± 3.4 | 4.8 ± 3.8 | .000 |
| ≤1 min (%) | 17/31 (54.8) | 13/55 (23.6) | — |
| 1–5 min (%) | 13/31 (41.9) | 14/55 (25.5) | — |
| >5 min (%) | 1/31 (3.1) | 28/55 (50.9) | — |
| Accompanying symptoms (%) | 17/23 (54.8) | 11/55 (20.0) | .001 |
| Physical injury (%) | 2/31 (6.5) | 7/55 (12.7) | .905 |
| Convulsion (%) | 4/23 (12.9) | 3/55 (5.5) | .251 |
| Urine or fecal incontinence (%) | 8/31 (25.8) | 1/55 (1.8) | .001 |
| Family history of sudden death or syncope (%) | 2/31 (6.5) | 1/55 (1.8) | .294 |
| History of heart disease (%) | 5/31 (16.1) | 2/55 (3.6) | .042 |
| Standard ECG abnormalities (%) | 29/31 (93.5) | 5/55 (9.1) | .000 |
Stay updated, free articles. Join our Telegram channel
Full access? Get Clinical Tree
