Syncope

1. Syncope
Anthony Ho, DO PGY4
Emergency Medicine

2. Introduction
•Symptom complex composed of brief loss of
consciousness associated with inability to
maintain postural tone that spontaneously
resolves without medical intervention
•Epidemiology
–2% of ER visits
–1 out of 4 persons will have in lifetime
–Elderly have the highest risk of morbidity
–Near syncope is the same process
–Differentiate from vertigo or dizziness

3. “Passed Out”

4. Pathophysiology
•Lack of blood flow to brainstem reticular
activating system for 10-15 seconds
•Reduction of cerebral perfusion by 35%
for 5-10 seconds
•Most common inciting event is drop in
cardiac output
•Least common is vasospasms or other
alterations in flow to CNS

5. Etiology
•Causes of syncope
–Cardiac
•Structural cardiopulmonary disease
–Valvular heart disease, aortic stenosis, tricuspid stenosis, cardiomyopathy, pulmonary HTN,
Congenital Heart disease, Myxoma, pericardial disease, aortic dissection, PE, MI, ACS.
•Dysrhythmias
–Bradydysrhythmias, Stokes-Adams attack, Sinus node disease, 2
nd
-3
rd
degree blocks,
pacemaker malfunction, tachydysrhythmias, Vtach, torsades de pointes, SVT, A Fib or Aflutter.
–Neural/Reflex mediated
•Vasovagal
•Situational
–Cough, micturition, defecation, swallow, neuralgia,
•Carotid Sinus Syndrome
–Orthostatic
–Psychiatric
–Neurologic
•TIA, Subclavian Steal, Migraine
–Medications

6. Cardiac Syncope
•6 month mortality >10%
•Underlying Structural Cardiopulmonary disease
–Think Aortic Stenosis in Elderly
–Think Hypertrophic Cardiomyopathy in Young
–PE can lead to Pulmonary outflow obstruction
–AMI or ischemia can lead to decrease CO
•Dysrhythmias
–Both tachy- and bradysrhythmias can lead to transient
hypoperfusion
–Syncope is SUDDEN ONSET without prodromal
symptoms

7. Vasovagal or Neurally/Reflex-
Mediated Syncope
•Syncope associated to inappropriate
vasodilation, bradycardia, or both in
response to inappropriate vagal or
sympathetic tone
•SLOW PROGRESSIVE ONSET with
associated prodrome
•Carotid Sinus Hypersensitivity, consider in
elderly patients with recurrent syncope
and negative cardiac evaluations

8. Orthostatic Syncope
•Occurs within 3 minutes of standing
•Orthostatic tests positive if decrease in SBP by
>20mmHg or drop in pressure to <90
• Non specific test: 40% of asymptomatic patients
>70 are positive
•Many life threatening causes of syncope have
orthostatic symptoms, do not attribute as benign
just because you have positive orthostatics

9. Psychiatric Illnesses
•Diagnosis of exclusion
•Associated with generalized anxiety and
major depressive disorders
•i.e. Hyperventilation syndrome 
hypocarbia cerebral vasoconstriction

10. Neurologic Syncope
•Loss of consciousness with persistent
neurologic deficits or AMS are not true
syncope
•Stroke Syndromes with syncope
–Brainstem ischemia
–Posterior circulation ischemia (diplopia,
vertigo, nausea)
–Subclavian steal syndrome
•Seizures often mimic syncope

11. Medication-Induced Syncope
•Usually contributes to orthostatic syncope
•Antihypertensive mediations (BB, CCB),
diuretics, and proarrythmics

12. Elderly Population
•Cardiovascular risk is the best predictor of
mortality with syncope
•Highest risk group
–Calcified blood vessels are less compliant
–LV becomes less compliant, increasing
dependence on atrial kick
•Incidence of vasovagal syncope
decreases with age
•Increased orthostatic syncope

13. Evaluation
•ED goal
–1. Avoid litigation!
–2. Admit patients that will benefit (receive a diagnosis)
from admission.
–3. Discharge patients that won’t die (or have
complications) before their follow-up.
–4. Diagnose in the ED reversible or deadly causes
•RISK STRATIFICATION
–Careful history
–Thorough Physical Exam
–EKG interpretation

14. History
•Symptoms of cardiopulmonary or
neurological origin
–Chest pain, palpitations, shortness of breath,
headache, abdomen or back pain, focal
deficits.
•Family history of dysrhythmias, sudden
cardiac death, prolonged QT

15. Physical Exam
•Focus on cardiovascular and neurological
systems
–Murmurs, rales (think HCM, AS)
–Focal neurological exam
–Rectal examination

16. EKG
•Cardiopulmonary disease
–Acute ischemia
–dysrhythmia (WPW, Brugada)
–Heart block
–Prolonged QT

17. Other test
•Carotid massage
–Only small number of patients with
hypersensitivity with have true Carotid Sinus
Syndrome
•Hyperventilation maneuver
•Neurologic Testing
–CT/MRI not warranted for isolated syncope

18. Unexplained Syncope
•Unknown etiology in 40% of patients
•If diagnosis made, 80% of the time is in
the emergency room!

19. Disposition
•SF Syncope Rules
–CHF
–Hematocrit <30
–EKG changes
–SBP<90
–SOB
•Boston Syncope Criteria
–25 criteria

20. Practice Guideline

21. Post ED Evaluation
•Cardiac Syncope
–Electrocardiographic monitoring
–Echocardiography
–Electrophysiology testing
–Stress testing
•Neurologic Syncope
–CT/MRA/Carotid Doppler
–EEG
•Reflex-mediated syncope
–Tilt-table testing
•Psychogenic
–Psychiatric testing