Pediatric emergency medicine trisk 1517 1517
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vasovagal syncope will most often have a normal ECG and reassuring physical
examination.
Other Tests
The patient with syncope should be placed on a continuous cardiac monitor to
evaluate the heart rate and rhythm while in the ED. Routine use of screening
blood tests in unselected pediatric patients with syncope will have a very poor
diagnostic yield. Consider testing for hypoglycemia (via blood glucose), anemia
(hemoglobin and hematocrit), pregnancy (urine pregnancy test), and recreational
drugs (urine toxicology screen) in appropriate clinical scenarios. Check the serum
chemistry in patients suspected to have electrolyte problems such as hypokalemia
or hypocalcemia. Cardiac enzymes are not routinely recommended in pediatric
patients with syncope. However, they may be necessary in an adolescent with
chest pain, or if the clinical evaluation suggests myocarditis or structural heart
disease.
Echocardiography and Other Cardiovascular Testing
The American Heart Association recommends the use of echocardiography only
in patients with clinically suspected heart disease or exercise-induced syncope. In
the absence of a history of exercise-induced syncope, positive family history,
abnormal physical examination, or abnormal ECG, the echocardiogram does not
contribute to the routine evaluation of pediatric syncope. However, the
echocardiogram can identify underlying heart disease such as hypertrophic
cardiomyopathy, aortic stenosis, or anomalous coronary arteries. It may suggest
pulmonary hypertension if significant tricuspid regurgitation or right ventricular
enlargement is present. Indications for an echocardiogram in a patient with
syncope include known heart disease, pathologic murmur, evidence of chamber
hypertrophy on ECG or chest radiograph, repolarization abnormalities with strain
or ischemia, ventricular ectopy or concern for myocarditis, cardiomyopathy, or
pulmonary hypertension.
Ambulatory ECG (Holter) monitoring may be useful if the screening ECG is
normal but the history still suggests an arrhythmia as source of syncope, if there
is exertional syncope, or if the relationship of a nonspecific ECG finding to
symptoms is unclear. An event recorder may be more practical because patients
are able to keep the monitor for a month and activate it at the time of their
symptoms. The stress test may help in eliciting changes in QT intervals in
patients with LQTS or arrhythmias in those with catecholaminergic polymorphic
ventricular tachycardia (CPVT), but should be ordered by a cardiologist. Exercise
