Pediatric emergency medicine trisk 1515 1515
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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
