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