Syncope

Published on 21/03/2015 by admin

Filed under Pediatrics

Last modified 22/04/2025

Print this page

rate 1 star rate 2 star rate 3 star rate 4 star rate 5 star
Your rating: none, Average: 0 (0 votes)

This article have been viewed 1323 times

Chapter 43 SYNCOPE

Theodore X. O’Connell

General Discussion

Syncope is a sudden, unexpected loss of consciousness associated with a loss of postural tone with spontaneous recovery. A syncopal event is one of the more dramatic and anxiety-provoking symptoms encountered by patients, and it often produces a diagnostic dilemma for the clinician. Syncope is a common manifestation of numerous disorders with a final common pathway of insufficient cerebral blood flow to maintain consciousness. Syncope must be differentiated from other disorders of altered consciousness, including seizures, sleep disorders, metabolic disorders, vertigo, presyncope, and psychiatric disorders.

In the evaluation of syncope, proving a specific diagnosis is often difficult because of a lack of residual abnormalities on examination or on initial diagnostic studies. The clinician must remember that syncope is a symptom, not a disease. By possessing an understanding of the common causes of syncope, the clinician can focus the history, physical examination, and diagnostic evaluation in each case. An understanding of the available diagnostic tests and their indications is imperative.

As many as 15% of children and adolescents will have a syncopal event between the ages of 8 and 18 years. Before age 6 years, syncope is unusual except in the setting of seizure disorders, breath-holding, and primary cardiac dysrhythmias. The cause of most cases of syncope can be placed into one of five categories: (1) autonomic, (2) cardiac, (3) psychiatric, (4) neurologic/cerebrovascular, and (5) metabolic/endocrine. Pediatric and young patients are most likely to have neurocardiogenic syncope (vasovagal syncope), psychiatric causes, and primary arrhythmic causes such as long QT syndrome and Wolff-Parkinson-White syndrome. The most common type of syncope in otherwise healthy children is vasovagal syncope. In infants who have recurrent and severe episodes of syncope that only have their onset in the presence of a particular parent or guardian, factitious or induced illness should be considered.

According to the American Heart Association, the differential diagnosis and evaluation of syncope in pediatric patients are similar to those in adults. The goal of the evaluation is to identify high-risk patients with underlying heart disease, which may include identifiable genetic abnormalities such as the long QT syndrome, Brugada syndrome, or hypertrophic cardiomyopathy.

Syncope associated with high-intensity physical activity is a typical presentation of hypertrophic cardiomyopathy or catecholaminergic polymorphic ventricular tachycardia and generally is evaluated with an electrocardiogram (ECG), echocardiogram, and an exercise stress test. Neurocardiogenic syncope is a common disturbance in the healthy child or adolescent. Breath-holding spells resulting from emotional upset have been reported in 2% to 5% of well patients.

Many algorithms exist for the evaluation of syncope, and most emphasize the importance of the history and physical examination in making an accurate diagnosis. Although algorithms may provide a guide for the evaluation of syncope, the various available algorithms each contain controversial elements. In addition, algorithms do not consider every clinical situation and are not designed to replace individual clinician judgment. The physician should understand the approach to the patient with syncope first and then consult algorithms to focus the diagnostic evaluation.

Medications Associated with Syncope

• α-agonists

• Anticholinergic agents

• Antiparkinsonian agents

• Antipsychotics

• β-adrenergic blockers

• Narcotics

• Vasodilators

Causes of Syncope

Reflex Mediated

• Vasovagal

• Situational (cough, defecation, micturition, swallow)

• Carotid sinus hypersensitivity

Cardiac

• Arrhythmia

• Hypertrophic cardiomyopathy

• Left ventricular outflow tract obstruction

• Myocarditis

• Pulmonary hypertension

• Tamponade

• Tumor or mass

• Valvular disease

Medication Effects

Metabolic Disorders

• Adrenal failure

Hypoglycemia

Neurologic Causes

• Migraine headache (syncopal migraine)

• Transient ischemic attack

Orthostatic Hypotension (Autonomic Dysfunction)

• Amyloidosis

• Diabetes

• Guillain-Barré syndrome

• Human immunodeficiency virus (HIV) infection

• Paraneoplastic neuropathies

• Parkinson’s disease

• Shy-Drager syndrome

Psychiatric Causes

• Hyperventilation

• Major depression

• Panic disorder

• Pseudoseizures

Other Causes

• Breath-holding

• Hyperventilation

• Hypovolemia

• Seizure (not a true case of syncope)

• Subclavian steal syndrome

Unknown

Key Historical Features

Situation in which syncope occurred (on standing, in a fearful situation, during micturition, with coughing, with exertion)

Activities leading up to the event

Prodromal symptoms (lightheadedness, warmth, nausea, sweating)

Associated cardiac symptoms (chest pain, palpitations, shortness of breath)

Associated neurologic symptoms (focal neurologic symptoms, headache, diplopia)

Witnessed events (tonic/clonic movements, tongue biting, urinary incontinence)

If witnessed, characterization of the patient’s appearance during and immediately following the episode

Duration of the episode

Time of day

Time of last meal

Previous history of syncope

Recent dehydration

Post-event symptoms

• Confusion may indicate seizure activity
• Injuries related to a fall
• Duration of recovery

Medical history, particularly:

• History of cardiac disease, including coronary artery disease, arrhythmias, or cardiomyopathy
• History of cerebrovascular ischemia
• History of pulmonary embolism or pulmonary hypertension
• History of gastrointestinal (GI) bleeding

Family history of syncope or sudden death

Medications

• Especially antihypertensive agents, antidepressants, vasodilators, narcotic analgesics, Q-T prolonging agents (tricyclic antidepressants), and hypoglycemic agents

Social history

• Alcohol or marijuana use
• Smoking history, which places the patient at risk for cardiopulmonary disease

Key Physical Findings

Vitals signs

Evaluation for orthostatic hypotension (defined as a decrease of at least 20 mm Hg systolic or 10 mm Hg diastolic blood pressure within 3 minutes of standing)

Funduscopic examination

Cardiovascular examination

• Carotid bruits
• Murmurs
• Jugular venous distention
• Loud S2
• Presence of an S3
• Pericardial friction rubs
• Blood pressures in both arms

Neurologic evaluation

• Mental status
• Pupil symmetry
• Evaluation for nystagmus
• Gait evaluation
• Balance and cerebellar function
• Romberg’s sign
• Deep tendon reflexes
• Proprioception

Suggested Work-up

ECG To identify abnormalities that may suggest an underlying cardiac cause for the syncope. Important findings include a long QT interval, preexcitation, evidence of conduction disorders, signs of coronary artery disease, or left ventricular hypertrophy that may be associated with ventricular tachycardia.
Complete blood count (CBC), electrolytes, blood urea nitrogen (BUN), creatinine, and glucose Indicated when an underlying disorder is suspected as a potential cause of syncope
Pregnancy test Should be considered in adolescent females

Additional Work-up

Cardiology consultation and echocardiogram Should be obtained if a heart murmur is appreciated, a family history of sudden death or cardiomyopathy exists, or the ECG is at all suspicious
Holter monitoring or telemetry monitoring Should be considered in patients with a history of palpitations associated with syncope. Also recommended for patients with known or suspected cardiac disease or a suspected arrhythmic cause of syncope.
Treadmill exercise stress test Should be considered if the syncopal event is associated with exercise
Tilt-table testing May be useful in patients with recurrent unexplained syncope with a suspected neurocardiogenic cause. May also be useful in patients without cardiac disease or in whom cardiac testing has been negative.
Cardiac catheterization and electrophysiologic testing May be indicated for patients with primary dysrhythmias and patients with preexcitation syndromes such as Wolff-Parkinson-White syndrome and in patients with a suspected bradyarrhythmic cause for syncope
Electroencephalogram (EEG) and neurologic consultation Indicated in patients exhibiting prolonged loss of consciousness, seizure activity, and a postictal phase of lethargy or confusion. EEG is indicated only when seizure is suspected because the positive yield of EEG is otherwise very low.
24-hour Holter monitor or a loop-recording event monitor May be useful in patients with a history of palpitations associated with syncope to help capture the cardiac rhythm
Computed tomography (CT) CT scanning of the head has a relatively low yield in patients with syncope and is not routinely indicated. It is recommended in patients with focal neurologic symptoms and signs. It may be performed in patients with seizure activity and head trauma to rule out intracranial hemorrhage.
Psychiatric evaluation Recommended for patients with recurrent unexplained syncope if there is no cardiac disease or if the cardiac evaluation is negative. Young patients and patients with many prodromal symptoms are at higher risk of having an underlying psychiatric disease associated with their episodes of syncope.
Admission to the hospital for observation with continuous ambulatory ECG and EEG monitoring May be indicated if syncope is reported to be occurring several times a day every day. Video surveillance may be included if factitious or induced illness is suspected.

References

1. Abboud F.M. Neurocardiogenic syncope. N Engl J Med. 1993;328:1117–1120.

2. Atkins D., et al. Syncope and orthostatic hypotension. Am J Med. 1991;91:179–185.

3. Calkins H. Pharmacologic approaches to therapy for vasovagal syncope. Am J Cardiol. 1999;84:20Q-25Q.

4. Cunningham R., Mikhail M.G. Management of patients with syncope and cardiac arrhythmias in an emergency department observation unit. Emerg Med Clin North Am. 2001;19:105–121.

5. Davis T.L., Freemon F.R. Electroencephalography should not be routine in the evaluation of syncope in adults. Arch Inter Med. 1990;150:2027–2029.

6. Di Girolamo E., et al. Effects of paroxetine hydrochloride, a selective serotonin reuptake inhibitor, on refractory vasovagal syncope: a randomized, double-blind, placebo-controlled study. J Am Coll Cardiol. 1999;33:1227–1230.

7. Kaufmann H. Neurally mediated syncope: pathogenesis, diagnosis, and treatment. Neurology. 1995;45(suppl 5):S12-S18.

8. Kapoor W.N. Syncope. N Engl J Med. 2000;343:1856–1862.

9. Kelly A.M., et al. Breath-holding spells associated with significant bradycardia; successful treatment with permanent pacemaker implantation. Pediatrics. 2001;108:698–702.

10. Lewis D.A., Dhala A. Syncope in the pediatric patient: the cardiologist’s perspective. Pediatr Clin North Am. 1999;46:205–219.

11. Linzer M., et al. Diagnosing syncope: Part 1: value of history, physical examination and electrocardiography. Clinical efficacy assessment project of the American College of Physicians. Ann Intern Med. 1997;126:989–996.

12. Linzer M., et al. Diagnosing syncope: Part 2: unexplained syncope. Clinical efficacy project of the American College of Physicians. Ann Intern Med. 1997;127:76–86.

13. Mahanonda N., et al. Randomized double-blind, placebo-controlled trial of oral atenolol in patients with unexplained syncope and positive upright tilt table test results. Am Heart J. 1995;130:1250–1253.

14. McLeod K.A. Syncope in childhood. Arch Dis Child. 2003;88:350–353.

15. Munro N.C., et al. Incidence of complications after carotid sinus massage in older patients with syncope. J Am Geriatr Soc. 1994;42:1248–1251.

16. Rodriguez-Nunez A., et al. Cerebral syncope in children. J Pediatr. 2000;136:542–544.

17. Sapin S.O. Autonomic syncope in pediatrics: a practice-oriented approach to classification, pathophysiology, diagnosis, and management. Clin Pediatr. 2004;43:17–23.

18. Schnipper J.L., Kapoor W.N. Diagnostic evaluation and management of patients with syncope. Med Clin North Am. 2001;85:423–456.

19. Strckberger S.A., et al. AHA/ACCF scientific statement on the evaluation of syncope: from the American Heart Association Councils on Clinical Cardiology, Cardiovascular Nursing, Cardiovascular Disease in the Young, and Stroke, and the Quality Care and Outcomes Research Interdisciplinary Working Group; and the American College of Cardiology Foundation: in collaboration with the Heart Rhythm Society: endorsed by the American Autonomic Society. Circulation. 2006;113:316–327.

20. Sutton R., et al. Dual chamber pacing in the treatment of neurally mediated positive cardioinhibitory syncope: pacemaker versus no therapy—a multicenter randomized study. The Vasovagal Syncope International Study (VASIS) Investigators. Circulation. 2000;102:294–299.

21. Sutton R., et al. Proposed classification for tilt induced vasovagal syncope. Eur J Pacing Electrophysiol. 1992;3:180–183.

22. Ward C.R., et al. Midodrine: a role in the management of neurocardiogenic syncope. Heart. 1998;79:45–49.

23. Weimer L.H., et al. Syncope and orthostatic intolerance for the primary care physician. Primary Care Clin Office Pract. 2004;31:175–199.

24. Zeng C., et al. Randomized, double-blind, placebo-controlled trial of oral enalapril in patients with neurally mediated syncope. Am Heart J. 1998;136:852–858.

25. Zimetbaum P., et al. Utility of patient-activated cardiac event recorders in general clinical practice. Am J Cardiol. 1997;79:371–372.

Related posts:

Gynecomastia Acute scrotum Proteinuria Anemia Transaminase elevation Limp