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 minutes and then measure the BP and heart rate Count the heart rate and respiratory rate for minute Next, make the patient stand for at least 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 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 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 ... 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... 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