Roberts, James R. MD
Children under 18 may frequent the ED with a complaint of syncope, though most cases are benign and turn out to be vasovagal in origin. A few cases turn out to be serious, if not life-threatening, however.
Occasionally, parents or other bystanders cannot accurately describe what happened. Of course, there is always the chance that this was a seizure, but with an observer present and a short recovery time, this cause should be a relatively quick rule-in or rule-out. Nothing will be found on laboratory or clinical evaluation in the ED for the majority of children, and being discharged home is safe.
The more serious causes of syncope, the vast majority of which are cardiac in origin, have a few common characteristics that can be fatal and demand urgent cardiology consultation. Cardiac arrhythmias are by far the most serious etiology. This month's column discusses the causes of syncope in children with evaluating for cardiac causes being a paramount ED issue.
Distinguishing Cardiac Syncope from Vasovagal Syncope in a Referral Population
Tretter J, Kavey RE
These authors note that cardiac and vasovagal syncope have dramatic differences in presentation, and a screening exam in the ED can accurately separate out patients who require further evaluation for a cardiac etiology. They state that cardiac referral is not necessary if vasovagal syncope is diagnosed. The authors, pediatric cardiologists at a tertiary referral center, suggest that many patients with benign syncope are referred to them for evaluation, which is not an unusual strategy for clinicians. This study compared a cardiology referral population with vasovagal syncope with those with cardiac syncope and sought to determine characteristics that indicate a cardiology evaluation is needed.
Syncope is a sudden loss of consciousness that results from markedly decreased cerebral blood flow. Recovery is rapid, back to baseline. Vasovagal reactions cause bradycardia and hypotension, and are often secondary to an exaggerated physiologic response that leads to transient loss of consciousness. Vasovagal syncope is not serious, but unraveling the underlying cause can be challenging in the ED.
About 15 percent of children overall experience a syncopal episode during their childhood, and underlying cardiac disease causes only one to five percent. This percentage is high enough to warrant investigation of the first episode in the ED. Sudden death in young athletes is an important issue, and has increased the number of patients presenting to physicians for a seemingly benign faint.
Important associated parameters of sudden cardiac death in children include historical factors, previous episodes of syncope, a concerning family history of cardiac disease, sudden death of a young relative, or an EKG abnormality. Other suspicious characteristics for fainting from a cardiac etiology include exertional syncope, no prodromal symptoms, or, less commonly, an event preceded by chest pain or palpitations.
The study included an evaluation of all referred patients who had a complaint of syncope and all pediatric records for those with a diagnosis known to present with syncope, such as a cardiomyopathy, a prolonged QT syndrome, various arrhythmias including Brugada syndrome, and myocarditis. The records were reviewed for clinical characteristics surrounding the event, a medical and family history, and any diagnostic workup.
Eighty-nine pediatric patients ages 4 to 18 were evaluated as outpatients by these pediatric cardiologists over the course of one year. All of these patients were ultimately diagnosed as having vasovagal syncope. Seven pediatric patients ages 4 months to 17 years presented with syncope from cardiac pathology over a 10-year period. All but one patient presented to the ED. Ten of the 17 presented in pulseless cardiac arrest and were resuscitated, representing an aborted sudden cardiac death. Twelve had a known cardiac history, three had a history of cardiac disease, and one had previous negative evaluation by an outpatient cardiologist but had a concerning family history for ventricular tachycardia.
The cardiac diagnoses included long QT syndrome in about half of the patients, and three of 17 had cardiomyopathy. About 65 percent of those with cardiac syncope required CPR, and about 71 percent of those with cardiac syncope had no previous syncopal events. Thirty-six percent of those with vasovagal syncope had a prior episode. A common triggering episode for a vasovagal faint did not identify any patient with a cardiac etiology.
About 25 percent of those with vasovagal syncope had an obvious reason, and both groups had the same number of complaints for chest pain and palpitations immediately preceding the syncope. Other symptoms such as lightheadedness, dizziness, visual changes, nausea, and diaphoresis were present in both groups, but significantly less common in those with a cardiac etiology compared with a vasovagal episode (41% v. 84%, respectively). The majority of patients with vasovagal syncope (82%) had a history of prolonged standing before the event. Sixty-five percent of patients in the cardiac group had syncope related to activity, and 63 percent were at peak activity. Three of the 17 patients in the cardiac syncope group had known cardiac disease, such as prolonged QT or a hypertrophic cardiomyopathy.
No concerning past medical history could explain the syncope in the vasovagal group. About half of the patients in the cardiac group had a concerning family history of heart disease in relatives or relatives with sudden cardiac death. About three-quarters of the patients with cardiac syncope had an abnormal EKG. Interestingly, only 67 percent of those with vasovagal syncope had an EKG performed before the referral cardiac evaluation, but all were subsequently interpreted as normal during cardiology follow-up.
The cardiologist's evaluation included an echocardiogram, treadmill testing, and a Holter monitor. The echocardiogram was abnormal in about half of the cases, and the treadmill testing was abnormal in about 85 percent, with 14 percent demonstrating a Holter monitor abnormality. No abnormal tests were found in the vasovagal group.
The authors identified exertional syncope at peak activity or just following exercise as a predictor of a cardiac etiology. Young athletes who faint during a game or after strenuous activity require cardiac evaluation, but some of them die suddenly with the first episode. Other concerns are a cardiac family history, abnormal physical examination, and an abnormal EKG. Using these criteria, all patients with a cardiac etiology would have been correctly identified as needing a cardiology evaluation. The authors suggest that all the patients with cardiac syncope would be identified in the ED by a careful focused history, a physical examination, and an EKG because they all had at least one of the characteristics.
The authors concluded that applying their screening protocol had a high sensitivity for suggesting a potentially serious cardiac cause, and they emphasizes that exertional syncope is an ominous sign that requires prompt cardiac evaluation. They noted, however, that post-exertional postural hypotension is also troubling, though it may be associated with vasovagal syncope. Aberrant coronary artery anatomy is a unique cause of syncope and sudden cardiac death, but this culprit would have no evidence on clinical examination.
These cardiologists emphasize the rare occurrence of cardiac syncope in children, and suggest that their screening protocol would accurately identify those requiring further cardiac evaluation. They noted that the vast majority of patients with cardiac syncope present to the ED, which would lead to referrals to them. This negative screen of the four abnormal characteristics should allow emergency physicians to competently inform children and families that the cause of syncope was benign.
Comment: True syncope means a loss of blood flow to the brain, loss of consciousness from the cerebral hypoxia, and loss of postural tone from which recovery is spontaneous. Benign syncope is relatively common, occurring in about 15 percent of children by the end of adolescence. Common conditions that mimic syncope are seizures, migraine syndromes, hysterical fainting, and hyperventilation. Other conditions include drug side effects, toxic exposure, such as ethanol or carbon monoxide, hypotension from volume depletion, situational syncope, and fainting following a coughing spell, micturition, blood draw, intramuscular injection, or emotional stress.
Some primary cardiac electrical abnormalities and structural cardiac abnormalities can cause syncope. (See table.) Any child with a known cardiac disorder requires special attention and likely a cardiac referral.
Obviously, the goal in the ED is to identify life-threatening conditions and provide proper referral. It's a no-brainer if the patient has had a cardiac arrest and was resuscitated, but the child that now appears normal following a syncopal episode creates stress among clinicians and family members. A careful history, physical examination, and EKG in competent hands should identify children with a cardiac cause of syncope.
Be especially concerned for a cardiac etiology when syncope occurs during physical exertion. Syncope after exertion is a less common cardiac etiology, but that does not mean it is not a possibility. Syncope in a patient experiencing emotional and physical stress is almost always vasovagal, but rare cases of catecholaminergic ventricular tachycardia can develop with emotional or physical stress. Palpitations or chest pain just prior to a syncopal episode may be a bit concerning for a cardiac etiology, but they are often seen with vasovagal syncope.
It's not uncommon to have some short-lived seizure-like movements or posturing with any cause of syncope. They usually indicate a non-cardiac cause, but could erroneously prompt a seizure diagnosis. Motor activity before the event followed by a prolonged recovery is more consistent with a seizure. Children with vasovagal syncope also often report prodromal symptoms such as dizziness, lightheadedness, sweating, nausea, weakness, or visual changes. Many have been standing for some time, especially in a hot environment (like in church during the summer).
Arrhythmia should be highly suspected in a child with a prior cardiac history such as Kawasaki syndrome, rheumatic heart disease, or myocarditis. The physical exam in the ED should probably consist of orthostatic vital signs and a careful cardiac exam, particularly looking for findings that suggest outflow obstruction. The classic hypertrophic cardiomyopathy is an outflow murmur that decreases in intensity with squatting, a posture that increases venous return to the heart.
Of course, the EKG is considered a standard part of the syncope workup, but it has a low diagnostic yield. Know a few specific abnormalities to look for; pediatric EKGs can be challenging to the EP. Of particular note is the rather rare Brugada syndrome, but the prolonged QT syndrome is likely better known and more common. MacCormick et al. highlighted an amazing statistic: Diagnosis of prolonged QTc was delayed in 40 percent of children who fainted or had a seizure, many of whose diagnosis was delayed for years because it was believed they had a seizure disorder. (Ann Emerg Med 2009;54:26.)
- A urine pregnancy test should be collected in all menstruating adolescents.
- Clandestine drug use is probably over-suspected, but a urine screen for drugs of abuse would be diagnostic in those who have an abnormal mental status in the ED. That would not cover the growing use of street drug, of course.
- Routine blood tests are often sent, but are of minimal value.
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ED Screen for Potential Cardiac Cause of Syncope
Abnormal Cardiac Screen Includes:∗
- Exertional syncope (common in athletes)
- Concerning family history (such as sudden death in young)
- Abnormal cardiac history/abnormal physical exam (murmur most common)
- Abnormal findings on EKG (Brugada, prolonged QTc, heart block, etc.)
One abnormal characteristic prompts cardiac referral.
∗ Symptoms such as lightheadedness, dizziness, visual changes, nausea, and diaphoresis occurred in both groups, but were significantly less common in those with a cardiac etiology compared with a vasovagal episode (41% v. 84%, respectively).
The majority of cases of serious cardiac syncope can be suggested by listening for a murmur, taking a careful event and family history, and ordering an EKG. An EKG is an essential part of the ED workup of all patients with syncope. Tachyarrhythmias and bradyarrhythmias, heart block, acute MI, and conduction defects are relatively easy to spot, but the clandestine culprit in a cardiac cause of syncope in children can be Brugada syndrome (see EKG).
Another subtle EKG is prolonged QTc interval. Brugada and prolonged QTC cause transient malignant ventricular arrhythmias, but both can be overlooked by the novice clinician. Fainting from these EKG abnormalities requires an urgent cardiology consultation in the ED.
Adapted from Proposed Diagnostic Criteria for the Brugada Syndrome: Consensus Report. Circulation 2002;106;(19)2514.
Causes of Syncope in Children and Adolescents
Primary Cardiac Electrical Disturbances
Long QTc syndrome/short QTc syndrome
Familial catecholaminergic polymorphic ventricular tachycardia
Preexicitation syndromes (such as Wolff-Parkinson-White)
Bradyarrhythmias (complete atrioventricular block, sinus node dysfunction)
Structural Cardiac Abnormalities
Hypertrophic cardiomyopathy/dilated cardiomyopathy
Coronary artery anomalies
Arrhythmogenic right ventricular dysplasia/cardiomyopathy
Valvular aortic stenosis
Congenital heart disease
Adapted from J Pediatr 2013;163(6):1618.
Findings in Pediatric Syncope
Adapted from J Pediatr 2013;163(6):1618.
∗ Screening positive for any one of these four characteristics had a sensitivity for a cardiac cause of syncope of 100 percent and a specificity of 60 percent. Any of these findings are an accurate and sensitive method for identification of cardiac syncope. If all four parameters are negative, cardiac referral may be unnecessary.
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