Pediatric emergency medicine trisk 379

FIGURE 76.1 An approach to the diagnosis of pediatric syncope.

Inquire about prodromal events such as pallor, lightheadedness, sweating,
vision changes, nausea, chest pain, palpitations, tinnitus, vertigo, diaphoresis,
hyperventilation, or any aura. Sometimes a patient will anticipate a syncopal
event and maneuver the body so as to avoid a sudden loss in postural tone. The
presence of palpitations prior to the event may suggest a cardiac cause, but can


also be seen in vasovagal syncope. Chest pain preceding syncope is almost never
present in patients with primary electrical disorders of the heart but is more likely
in patients with cardiomyopathies, congenital coronary artery abnormalities, or
aortic disease (e.g., dissection or rupture associated with Marfan syndrome). With
seizures, there may be posturing, clonic contractions or incontinence followed by
postictal confusion, and the total time of the event is likely to be longer than that
in a true syncope. Rarely, syncope may be severe enough to result in
cardiopulmonary resuscitation, and any interventions by bystanders or emergency
medical services should be discussed. Children and especially young athletes who
have been outdoors for prolonged periods in warm weather may be at risk for
dehydration and heat syncope.
The past medical history may also provide information about the etiology for
syncope. Families may give a history of congenital heart disease, cardiac surgery
or acquired conditions such as Kawasaki disease, rheumatic heart disease,
myocarditis, or arrhythmia. Patients with seizure disorders, anemia, diabetes, or
psychiatric conditions may also present with syncopal events. It is important to
ask pubescent and adolescent girls about their menstrual history and the date of
the last menstrual period, since pregnancy or dysfunctional uterine bleeding with
resulting anemia may cause syncope. Adolescent patients with eating disorders
may also present with syncope. Use of therapeutic or recreational drugs that cause
dehydration, heart rhythm disturbances, hypotension or mental status changes
may be associated with syncope.

When inquiring about the family history, ask if there was a sudden death of any
family member less than 50 years of age, any unexplained deaths, sudden infant
death syndrome (SIDS), drowning, or motor vehicle crashes. Such events may
occur in patients with LQTS or Brugada syndrome. Also ask for any family
history of enlarged heart or heart rhythm problems, heart attack at age 50 or
younger, pacemaker or implanted defibrillator, deafness at birth,
hypercholesterolemia, Marfan syndrome, or unexplained fainting or seizures. A
family history of vasovagal syncope may be present; genetic factors have been
found to play a role in this disorder, though most cases follow complex patterns
of inheritance and autosomal dominant inheritance is rarely seen.
In most children with syncope, the physical examination is normal. The
physical examination should focus on the vital signs, and the cardiac and
neurologic examinations. Calculate the body mass index (BMI) in patients
suspected to have an eating disorder and inspect the patient for a Marfanoid body
habitus. Check the patient for orthostatic changes as follows. Place the patient in
the supine position for 2 minutes and then measure the BP and heart rate. Count


the heart rate and respiratory rate for 1 minute. Next, make the patient stand for at
least 1 minute and measure the BP and heart rate again. Observe for dizziness or
lightheadedness. If the patient is unable to stand, allow him or her to sit with the
feet dangling for at least 2 minutes. The test for orthostatic hypotension is
positive if the patient’s systolic BP decreases ≥20 mm Hg or the diastolic BP
decreases ≥10 mm Hg. In individuals 12 to 19 years of age, orthostatic
tachycardia is defined as a sustained increase in heart rate of ≥40 bpm occurring
within 10 minutes of moving from a recumbent to a quiet (nonexertional)
standing position. In the setting of hypovolemia, a positive test for orthostatic
intolerance indicates a volume deficit of at least 10 to 15 mL/kg.
The presence of orthostatic hypotension does not rule out other causes of
syncope, particularly LQTS. During the cardiac examination, auscultate for the

character of the heart sounds, abnormality in heart rhythm and the presence of a
gallop, ejection click, rub, or murmur. Soft or muffled heart sounds may be heard
with pericardial effusion. A loud second heart sound might point to pulmonary
hypertension. Changing heart murmurs are observed in acute rheumatic carditis,
and a gallop may be auscultated in heart failure. Test the effect of maneuvers such
as positional changes and holding the breath on the character of any heart murmur
that is noted. The intensity of the systolic ejection murmur in HOCM decreases
upon assuming a squatting position and increases with the Valsalva maneuver and
upon standing. Search for signs of heart failure such as elevated jugular venous
pressure, basilar lung crepitations, gallop, pathologic murmur, hepatomegaly, or
edema. Finally, complete a full neurologic examination.

Electrocardiogram (ECG)
This is a very useful test in the diagnosis of cardiac causes of syncope, and is
recommended in all children who present with their initial episode of fainting or a
similar event. Table 76.2 summarizes the ECG findings observed in important
cardiac conditions that cause syncope. The 12-lead ECG provides information
about both heart rhythm and atrioventricular (AV) conduction. Important findings
include the delta wave signifying an accessory pathway and Wolff–Parkinson–
White syndrome, a prolonged QT interval, high-grade ventricular ectopy,
complete AV block, and extremes of sinus, atrial, or junctional rates. Clinicians
should also be vigilant for surface ECG changes specific to Brugada syndrome
and the increased QRS voltages with ST-segment–T-wave changes and deep Q
waves in inferior and lateral leads characteristic of hypertrophic cardiomyopathy.
Nonspecific ECG findings include moderate sinus arrhythmia, moderate sinus
bradycardia, simple junctional rhythm, unifocal ventricular premature
contractions, and right bundle branch block. Resting bradycardia may indicate


drug ingestion or cardiac manifestations of eating disorders or central nervous

system trauma, but can also be seen in healthy adolescents. Syncope is
uncommon in patients with first- or second-degree heart block, but complete heart
block can potentially lead to more serious symptoms. The combination of history,
physical examination, and ECG allows identification of a cardiac cause of
syncope in a majority of affected children, with reported sensitivity as high as
96%. Patients with clinical features or ECG findings suggestive of heart disease
should be referred to a cardiologist.
TABLE 76.2
ECG FINDINGS IN IMPORTANT CARDIAC CAUSES OF PEDIATRIC
SYNCOPE
Cause

ECG findings

Long QT syndrome QTc >450 msec; morphology of QT segment and T wave
may vary in different genetic subtypes
Brugada syndrome Elevated ST segments in precordial leads V1 and V2.
Coving seen in Type 1 syndrome; right bundle branch
block
Wolff–Parkinson– Classic triad of delta wave, shortened PR interval, and
White syndrome
widened QRS complex. There is a slurring in upstroke
of R wave. Secondary ST-segment–T-wave changes are
directed opposite to the major delta wave and QRS
complex changes
Hypertrophic
The most frequent abnormalities found are large amplitude
obstructive
QRS complexes and associated ST-segment and T-wave
cardiomyopathy

changes consistent with left ventricular hypertrophy.
(HOCM)
Deep, narrow Q waves in leads II, III, aVF, V5, and V6
are most characteristic and specific findings of HOCM.
Left atrial enlargement is also seen
Bradycardia
Second- and third-degree heart block
To summarize, risk factors for a cardiac etiology for syncope include the
absence of prodromal symptoms, palpitations that occur seconds before loss of
consciousness, lack of a prolonged upright posture, exertion-related syncope or
syncope that occurs with auditory or emotional stimuli, a family history of sudden
cardiac death, abnormal physical examination, and abnormal ECG. Patients with