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From the 2010 Cape Cod Conference on Pediatrics for the Primary Care Physician, presented by Nemours
The goals of this program are to improve diagnosis of the cause of syncope, management of neurocardiogenic syncope, and screening for participation in sports in pediatric patients. After hearing and assimilating this program, the clinician will be better able to:
1. Describe the physiology of syncope as it relates to upright posture.
2. Determine underlying causes of syncope in pediatric patients.
3. Differentiate among different arrhythmias that can cause syncope in pediatric patients.
4. Recognize behavioral causes of syncope.
5. Identify red flags for conditions that might preclude participation in sports for children and adolescents.
In adherence to ACCME Standards for Commercial Support, Audio-Digest requires all faculty members to disclose relevant financial relationships within the past 12 months that might create any personal conflicts of interest. Any identified conflicts were resolved to ensure that this educational activity promotes quality in health care and not a proprietary business or commercial interest. For this program, Dr. Temple and the planning committee reported nothing to disclose.
Dr. Temple spoke at Cape Cod Conference on Pediatrics for the Primary Care Physician, held August 6-9, 2010 in Hayannis, MA, and sponsored by Nemours. The Audio-Digest Foundation thanks Dr. Temple and Nemours for their cooperation in the production of this program.
Syncope in Children
Joel Temple, MD, Director of Electrophysiology, Division of Pediatric Cardiology, Department of Pediatrics, Nemours, Wilmington, DE
Physiology of syncope: most patients lose consciousness during upright posture; physiologic changes during standing — redistribution of blood (»25% goes to lower extremities); £40% decrease in stroke volume; decrease in blood pressure (BP); activation of baroreceptors; increase in catecholamines, heart rate, and vascular tone; most cases of syncope caused by failure in these responses; occurs in »1 in 4 pediatric patients
Patient history: important in determining cause of syncope; includes, eg, whether patient exercising, sitting, or standing at time of episode, and hydration level; prodrome evident in most cases of benign (but not malignant) syncope; determine whether palpitations, visual changes, chest pain, or shortness of breath occurred; presence of paresthesia indicates neuropathy or hypocalcemia with hyperventilation; evaluate for injuries; inquire direction of fall (typically, forward); assess caffeine intake and color of urine to determine hydration level; check for history of lightheadedness; further clarification needed when — syncope reported “with exercise” (during activity [more alarming] vs following activity); syncope associated with seizure activity; patient reports “dizziness”; distinguish vertigo (ie, accompanied by nystagmus) from lightheadedness; “syncope” follows trauma (not true syncope); relevant family history – sudden death; sudden infant death syndrome (SIDS); pacemakers or defibrillators; deafness (has association with long QT interval); fainting
Physical examination: generally does not provide much information, with exception of evaluation for heart murmur; if present, determine whether louder upon standing (indicates mitral valve prolapse or hypertrophic cardiomyopathy)
Diagnostic tests: electrocardiography (ECG); tilt table test (not usually necessary); exercise test; 24-hr Holter monitor (if palpitations present); echocardiography; electrophysiology (EP) study rarely appropriate; perform tests for confirmation, not exploration (except ECG)
ECG: look for — normal sinus rhythm; appropriate heart rate; atrioventricular (AV) block; evidence of hypertrophy or strain; ventricular preexcitation with Wolff-Parkinson-White (WPW) pattern; epsilon waves; normal QT interval
Slow arrhythmias: warrant consultation with cardiologist
Fast arrythmias: more heterogeneous; supraventricular tachycardia (SVT) due to WPW syndrome only type associated with sudden death (when combined with atrial fibrillation with accessory pathway)
Long QT syndrome: occurs in »1 in 5000 people; causes many deaths, typically in adolescents and teens; autosomal dominant inheritance most common; symptoms usually occur with exertion or startling; mortality occurs due to torsades de pointes” arrhythmia; diagnosed by measuring corrected QT (QTc; QT divided by square root of preceding R-R interval); 460 msec considered upper limit of normal; can present with normal ECG findings at rest, but mortality usually associated with QTc of ³500 msec
Brugada syndrome: characterized by pronounced ST elevation with inverted T waves; leading cause of unexplained death in Asian men; arrhythmias tend to occur during febrile periods (during sleep and after high-carbohydrate meals) and exercise; genetic testing available, but not typically helpful; heart pattern similar to patients on drugs or with electrolyte abnormalities or fever
Catecholaminergic polymorphic ventricular tachycardia (CPVT): more common than any single type of long QT syndrome; presents as arrhythmia with exertion; arrhythmia described as bidirectional VT with alternating ventricular beats, followed by ventricular fibrillation (VF); usually associated with autosomal dominant inheritance; red flags include — syncope preceded by palpitations; syncope with exertion, excitement, or swimming especially concerning; abrupt syncope without prodrome; family history of syncope, SIDS, sudden death, or deafness
Structural Heart Disease
Hypertrophic cardiomyopathy: leading cause of sudden death in “healthy” young athletes; death typically occurs due to VF; tends to appear between 14 and 17 yr of age (ie, not ruled out by echocardiography at 8 yr of age); genetic testing can identify >50% of cases; characterized by increasing murmur volume while standing; symptoms (usually chest pain) tend to occur during exercise; significant ECG findings —large R waves in V6; large S waves in V1; deep septal Q waves in inferior leads II, III, and augmented limb lead (aVF); inverted T waves in V6 with strain pattern (asymmetrical inversion with depressed J point); upright T waves in V1 (abnormal in children)
Coronary artery anomalies: second leading cause of sudden death in “healthy” young athletes; common examples include single coronary and abnormal anomalous coronary crossing between arteries; symptoms usually present with exertion; disease has 79% relative risk of sudden death with exercise; not associated with genetic predispositions, warning signs, or findings on ECG, stress test, or echocardiography
Arrhythmogenic right ventricular (RV) dysplasia (ARVD): occurs in 1 in 5000 individuals; second leading cause of sports-related deaths in parts of Europe (particularly Italy); characterized by replacement of muscles of RV free wall with fat and fibrosis, with resulting arrhythmias (usually during stress and exercise); can be diagnosed by magnetic resonance imaging (MRI); characterized by epsilon waves after QRS wave complex
Marfan syndrome: associated with aortic root dilation and rupture; affected patients have positive thumb sign (thumb completely crosses palm when fist clenched); ECG reveals abnormally large aorta (results in 8-fold increase in stress)
Red flags: syncope with exercise; syncope with chest pain; family history of structural heart disease, enlarged heart, or heart transplantation; increased murmur volume with standing; hypertrophy or strain on ECG
Other Causes of Syncope
Orthostatic intolerance: includes orthostatic hypotension (syncope and lightheadedness upon standing); caused by slowed activation of compensatory mechanisms that combat low BP when standing; exacerbated by conditions that reduce BP (eg, hypovolemia, vasodilated states)
Neurally mediated reflexive syncope (vasovagal syncope)
Vasodepressor syncope: eg, during venipuncture, after emotional shock, during hair grooming
Cardioinhibitory (neurocardiogenic) syncope: caused by Bezold-Jarisch reflex; activated by decreased venous return or increased catecholamines, which cause decreased heart rate, withdrawal of sympathetic tone, vasodilation, and decreased BP; occurs with prolonged standing and after (but not during) exercise (catecholamines already elevated; blood pools in legs when activity stops); typically associated with prodrome; aborts with lying down; tends to affect tall thin women with chronic fatigue; common in adolescents, but unusual in children <8 yr of age; diagnosable via tilt table test
Red flags for diagnosis other than syncope: frequent absences from school; selective loss of neurologic function; unusual syncope with history of risky social behavior (investigate for possible child abuse); multiple daily episodes; changing symptom characteristics
Treatment of neurocardiogenic syncope
Nonpharmacologic: effective in »85% of cases; includes adequate hydration, avoidance of caffeine, and increased intake of sodium (if not hypertensive); evaluate efficacy after 1 mo
Pharmacologic: fludrocortisone acetate — contraindicated with hypertension or glaucoma; requires consumption of potassium-rich foods (causes potassium wasting); study showed benefit no better than placebo (but still significantly effective); other options — b-blockers or midodrine (both have many side effects); selective serotonin reuptake inhibitors (mildly effective)
Postural orthostatic tachycardia syndrome (POTS): tachycardia with evidence of cerebral hypoperfusion with upright posture; chronic condition more commonly found in girls and women; often triggered by viral illness (eg, Epstein-Barr); associated with low quality of life scores; symptoms —intense palpitations with upright posture; chronic fatigue; lightheadedness; occasional syncope; shortness of breath; chest pain; gastrointestinal complaints; cognitive changes; mottling of lower extremities; “crashes” after day of exertion; often seasonal; diagnostic indicators — positive tilt table test; elevated catecholamines; treatment — hydration, medication (midodrine or b-blockers), exercise, and use of compressive clothing
Behavioral Causes of Syncope
Hyperventilation syndrome: characterized by subjective shortness of breath described as inability to fill lungs with air; associated with anxiety and paresthesias
Breath-holding spells: cyanotic breath-holding spells; typically provoked by anger; not considered dangerous (no long-term side effects); no treatment necessary (other than reassurance)
Pallid breath-holding spells: provoked by pain; caused by reflexive asystole; treatment typically unnecessary, but occasional patient may require pacemaker; patients often demonstrate tonic-clonic activity; may be related to neurocardiogenic syncope in adulthood
Questions and answers: swimming and syncope — more intense exertion than other forms of exercise; cold water may cause shock to system; echocardiography — not needed for most patients with syncope (majority diagnosed with vasovagal syndrome [diagnosis of exclusion] via history); ECG — during screening for participation in sports, may be only opportunity to detect potential cause of sudden death; should always be read by cardiologist
Screening Patients for Sports: A Cardiologist’s Perspective
Goals: to determine whether patient has any relative or absolute contraindications (eg, lack of physical or emotional maturity, improperly healed fractures, single paired organs, asthma)
Sports and increased risk for sudden death: incidence of sudden death in general Italian population 0.9 per 100,000, vs 2.3 per 100,000 among young athletes; causes of sudden death — trauma (eg, blunt trauma, commotio cordis); pre-existing noncardiac conditions (eg, asthma, cerebral aneurysms, ruptured aortic aneurysm or aortic root); coronary artery disease; congenital coronary anomalies; congenital heart disease (hypertrophic cardiomyopathy, ARVD); primary arrhythmia disorders
History: inquire about — chest pain with exertion (if affirmative, determine whether sharp, pleuritic, and nonexertional [noncardiac] or associated with exertion, crushing sensation, pallor, and lightheadedness [cardiac]); palpitations during exertion or rest (if present, determine whether onset abrupt or gradual) syncope with exertion; family history of sudden death (particularly with exercise), defibrillator use, fainting, or seizures
Physical examination: assess whether murmur volume increases upon standing; participation in sports contraindicated for patient with hypertrophic cardiomyopathy (but not with mitral valve prolapse)
Electrocardiography: not recommended or discouraged by American Academy of Pediatrics or American Academy of Family Physicians; warranted by suspicious history or examination; determine age-based appropriateness of heart rate; assess for AV block, hypertrophy or strain, preexcitation, WPW patterns, normal QTc, epsilon waves, Brugada pattern, and normal sinus rhythm; study revealed 40% incidence of abnormal ECG in 1000 athletes (5% had evidence of disease)
Noncardiac conditions: Marfan syndrome — autosomal dominant trait linked to defect in fibrillin gene; autopsy study of sudden deaths occurring during sports revealed 3 of 11 patients had ruptured aortic aneurysm (suspicious for Marfan syndrome); commotio cordis — occurs when patient receives impact (of 20-50 mph) directly to heart during repolarization of T wave; relatively uncommon (93 cases reported between 1985 and 2001)
Structural heart disease: hypertrophic cardiomyopathy —prevalence 1 in 500; autosomal dominant inheritance (family diagnosis considered prognostic); genetic testing and MRI can assist with diagnosis; tissue Doppler imaging can reveal early diastolic dysfunction; ARVD — second leading cause of sports-related sudden death in certain parts of Europe, yet only one-tenth as common as hypertrophic cardiomyopathy (ie, hypertrophic cardiomyopathy rarely fatal); symptoms include syncope or palpitations with exertion
Arrhythmias: long QT syndrome — sudden death reported as first symptom in 30% to 40% of affected patients; 57% die by 20 yr of age; genetic testing associated with 85% to 90% identification rate; 12 varieties, but types 1, 2, and 3 comprise »95% of cases; type 1 causes death through excitement or exertion; type 2 causes death through startling; type 3 causes death during sleep; treated with avoidance of strenuous exercise and startling, b-blocker therapy, implantable cardiac defibrillators, and surgery (Canada and Europe only); red flags include syncope or palpitations with exertion, syncope with startling, and family history of sudden death or deafness; CPVT — presentation similar to long QT syndrome without QT prolongation; more likely to cause death during exercise than long QT syndrome; typically treated with b-blockers; examination and ECG findings usually negative; exercise test can be diagnostic; Brugada syndrome — affects 1 in 2000 individuals; red flags include syncope or palpitation during exertion or fever, and Asian descent; WPW syndrome — family history not prognostic; warning signs include occasional palpitations and history of cardiac arrest
Red flags for arrhythmias: syncope with exertion or excitement; syncope preceded by palpitations; abrupt syncope without prodrome; syncope while swimming (unexplained drowning); family history of syncope, seizures, SIDS, sudden death, or deafness; abnormal body habitus (Marfan syndrome); increased murmur volume with standing; abnormal findings on ECG
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