Syncope

Syncope: Excerpt from The 10-Minute Diagnosis Manual: Symptoms and Signs in the Time-Limited Encounter

James C. Chesnutt

Syncope is a common and concerning medical problem, which accounts for 3% of emergency room visits and up to 6% of hospital admissions. Although the cause of syncope can be life-threatening (e.g., ventricular tachycardia) and the result can be devastating (e.g., fractured hip), a definitive explanation for syncope is found less than one half of the time, with an average cost of $16,000/patient (1). Syncope recurrence is approximately 20% per year compared with an incidence of 2% for an initial episode of syncope (2).

Approach.

 Syncope is a brief loss of consciousness with collapse resulting from transient brain dysfunction based on decreased blood flow or neurologic insult. Syncope can be categorized based on the causative mechanism (Table 2.6). The most common causes are vasovagal (18%), arrhythmia (14%), neurologic (10%), orthostatic hypotension (8%), and situational (5%) (3).

History

A. What are the symptoms or circumstances related to the syncope?

1. Dizziness preceding syncope is highly associated with a psychological cause (24%) versus syncope without preceding dizziness (5%) (3). Dizziness with syncope can also be associated with arrhythmia.

2. Important history includes palpitation, duration of prodrome and recovery, and presence of postural or exertional symptoms.

3. Related environmental factors include heat, dehydration, and alcohol.

B. Which disease, risk factor, or family history is present?

1. Organic heart disease is associated with arrhythmia and increased risk of death.

 2. Psychiatric illnesses most commonly associated with syncope are major depression (12.2%), alcoholism (9.2%), generalized anxiety disorder (8.6%), and panic disorder (4.3%). These correlate with a higher rate of recurrent syncope, younger age, and a more benign course (4) (Chapters 3.1 and 3.3).

 3. Older age (>60 years) is more highly associated with arrhythmias, orthostatic hypotension, medication side-effects, and situational (e.g., micturition) syncope.

 4. Ask about diabetes mellitus, neuropathy, anemia, and other chronic diseases.

 5. Inquire about a family history of sudden death, hypertrophic cardiomyopathy, or other organic heart disease.

C. What medicines does the patient take? The most commonly implicated are antihypertensives and antidepressants. Others include antianginals, analgesics, and sedatives.

Physical examination

What are the essential aspects to cover?

A. General: mental status, temperature, hydration status, pallor, or cyanosis.

 B. Vital signs: tachycardia, bradycardia, irregularity, or orthostatic hypotension.

 C. Cardiovascular: heart sounds, murmurs, bruits, edema, rales, and pulses.

 D. Neurologic: cranial nerves, reflexes, strength and sensation, tremor, Romberg’s sign, gait, and cerebellar signs.

Testing.

Which tests are useful in diagnosing syncope?

 A. Electrocardiogram (ECG). The most important single initial test to evaluate syncope is the ECG; it is easy and inexpensive and can quickly identify life-threatening arrhythmias or ischemia. Although the diagnostic yield is only 5% (3), if the ECG is normal, ischemia, arrhythmias, and organic heart disease are very unlikely (5). If the ECG is abnormal but does not clearly demonstrate a likely cause for syncope (complete heart block or runs of ventricular tachycardia, for example), other tests are needed to clarify the underlying problem that may be related to the syncope. The result of the ECG, therefore, helps to direct the course of further workup.

 B. Cardiac monitors

 1. Holter monitor or telemetry performed for 24 hours. For patient with organic heart disease, this gives a diagnostic yield of from 2% for arrhythmias correlated to symptoms to 21% with unrelated arrhythmias. Extending this monitoring to 72 hours is not useful (5).

 2. A loop event monitor is a portable, prolonged ambulatory event recorder indicating if there is recurrent syncope and no organic heart disease (yield = 24% to 47%) (4).

 C. Electrophysiologic studies. This invasive cardiac monitoring and arrhythmia induction procedure gives a 50% diagnostic yield for those with organic heart disease or abnormal ECG (compared with 10% if no organic heart disease) (4). This is considered the gold standard for arrhythmia diagnosis but it is expensive and invasive. Powerful predictors of a positive test are an ejection fraction less than 40%, bundle branch block, or atrial fibrillation (5).

 D. Tilt table testing is indicated for unexplained, recurrent syncope when arrhythmia or organic heart disease is excluded and neurocardiogenic syncope is suspected. In this setting, the sensitivity is 67% to 83% and specificity is 90% (4).

E. Echocardiogram and stress tests are used only to evaluate exertional symptoms (echo first in this case) or suspected organic heart disease.

F. Computed tomography scan is used to evaluate focal neurologic signs.

G. Electroencephalogram is indicated for seizure activity only (Chapter 4.7).

H. Carotid massage. Consider this if the patient is aged more than 60 years with unexplained syncope. Perform in the clinic if no bruits, ventricular tachycardia, recent stroke, or myocardial infarction.

I. Blood tests, including hematocrit, serum chemistries, and pregnancy test, are not for screening; order only if a specific medical condition is suspected.

J. Psychiatric evaluation is useful in the setting of a high recurrence rate in a young patient without resultant injuries and no evidence of organic heart disease.

Diagnostic assessment.

 The keys to the diagnosis of syncope are the history, physical examination, and ECG, yielding a diagnosis 45% of the time. The history and physical should focus on cardiac, neurologic, and medication-related issues. Directed testing can add 8% to diagnosis (3). Further classification by age and presence of organic heart disease can help focus evaluation and treatment. If organic heart disease is present or the ECG is abnormal, inpatient telemetry monitoring and electrophysiologic studies are recommended. If organic heart disease is not evident, ambulatory loop ECG and psychiatric evaluations are indicated, as well as possible tilt table testing (4).

Although most syncope patients can be evaluated in the outpatient setting, hospitalization is recommended for those with organic heart disease, chest pain, a history or suspicion of arrhythmia, or presence of neurologic symptoms or signs suggesting transient ischemic attack or stroke. The extent of severity of the organic heart disease is the key determinant of mortality and should direct evaluation and therapy (2). Despite extensive evaluation and testing, the diagnosis may still be elusive in approximately 40% of patients with recurrent syncope, but fortunately these patients have a low incidence of morbidity and mortality.

References

1. Grubb BP, Kosinski D. Neurocardiogenic syncope and related syndromes of orthostatic intolerance. Cardiology in Review 1997;5:182–190.

2. Kapoor WN, Hanusa BH. Is syncope a risk factor for poor outcomes? Comparison of patients with and without syncope. Am J Med 1996;100:646–655.

3. Linzer M, Yang EH, Estes NA 3rd, et al. Clinical guideline: diagnosing syncope. Part 1: Value of history, physical examination, and electrocardiography. Ann Intern Med 1997;126:989–996.

4. Linzer M, Yang EH, Estes NA 3rd, et al. Clinical guideline: diagnosing syncope. Part 2: Unexplained syncope. Ann Intern Med 1997;127:76–86.

5. Meyer MD, Handler J. Evaluation of the patient with syncope: an evidence based approach. Emerg Med Clin North Am 1999;17:189–201.

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Book Source Details

• Book Title: The 10-Minute Diagnosis Manual: Symptoms and Signs in the Time-Limited Encounter
• Author(s): Robert B. Taylor (editor)
• Year of Publication: 2000
• Copyright Details: The 10-Minute Diagnosis Manual: Symptoms and Signs in the Time-Limited Encounter, Copyright © 2000 Lippincott Williams & Wilkins.

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Copyright notice for book excerpts: Copyright © 2008 Lippincott Williams & Wilkins. All rights reserved.

More About This Book: Title: The 10-Minute Diagnosis Manual: Symptoms and Signs in the Time-Limited Encounter Authors: Robert B. Taylor (editor) Publisher: Lippincott Williams & Wilkins Copyright: 2000 ISBN: 0-78172-094-X

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