• Syncope is defined as a transient loss of consciousness and postural tone with subsequent spontaneous recovery.
  • It results from transient cerebral hypoperfusion from a variety of causes.
    • As opposed to loss of consciousness caused by electrical disorders of the brain (ie, seizures)
  • It is most commonly benign but is associated with life-threatening conditions.
  • A post-ictal period is notably absent, differentiating syncope from seizure.


  • Transient loss of consciousness
  • Complete recovery without intervention
  • Other symptoms and exam findings vary with underlying etiology.
Classic Presentation of Syncope
Presentation Suspected Diagnosis
17-year-old male, syncope during running Hypertrophic cardiomyopathy
29-year-old female, syncope and abdominal pain Ectopic pregnancy
68-year-old male, syncope and abdominal or flank pain Abdominal aortic aneurysm
34-year-old female, sudden severe headache and syncope Subarachnoid hemorrhage
72-year-old male with history of MI and CHF,  syncope at home Dysrhythmia
40-year-old female, syncope while standing in line, prodrome of nausea, sweating, warmth Vasovagal
78-year-old female with cancer, sudden onset of  SOB and syncope PE
Hx and Physical Exam
Neurally mediated (can be diagnosed with tilt-table testing in equivocal cases)
  • Supporting features: absence of cardiac disease; or a long history of recurrent syncope
  • Precipitating event: fear, pain, unpleasant sight, sound or smell, venipuncture, prolonged standing, or crowded and hot environment
  • Prodromal symptoms: feeling hot, nausea, lightheadedness, diaphoresis, and visual changes
Carotid sinus hypersensitivity with head rotation or pressure on lateral neck
  • Carotid massage (positive with ↓ SBP ≥ 50 mmHg or asystole ≥ 3 sec)
Orthostatic hypotension
  • Check for orthostasis (↓ ≥ 20 mmHg sBP, ↓ ≥ 10 mmHg dBP ↑ HR 10–20 from supine to standing) within 3 minutes of standing.
  • Autonomic nervous system failure: amyloidosis, diabetes, alcoholism, Parkinson disease, or Shy-Drager syndrome
  • Syncope occurring within 2 min of standing is suggestive of orthostasis
Cardiac syncope
  • Exertion-related, occurring at rest or in supine location, family history of sudden death or associated with chest discomfort, palpitations, or dyspnea
  • Bradycardia
    • Sinus node dysfunction, AV conduction disease, implanted device malfunction
  • Tachycardia
    • Supraventricular, ventricular, paroxysmal SVT
  • Structural disease
    • Valvular (mitral stenosis, aortic stenosis), ACS, CAD, hypertrophic cardiomyopathy
    • Cardiac masses
    • Pericardial disease/tamponade
    • Congenital abnormalities
    • Prosthetic valves dysfunction
  • Dysrhythmias
    • Long and short QT syndromes
    • Pre-excitation syndromes (i.e. WPW, LGL)
    • Brugada syndrome
    • Arrythmogenic right ventricular dysplasia (and other ventricular dysrhythmias)
Subclavian steal syndrome
  • Occurs with arm activity; difference > 10 mmHg in systolic BP between arms
Situational syncope:
  • cough, micturition, or defecation-induced syncope
Neuropsychiatric: seizures, vertebrobasilar insufficiency, or a conversion disorder
  • Seizures often have postictal period for > 2 min, tongue biting, tonic-clonic activity, and incontinence



  • It may be difficult to differentiate syncope from seizure.
    • A history of seizures makes a seizure more likely.
    • In rare instances, true syncope leads to seizure.
    • Both may be associated with extremity movement and urinary incontinence.
    • A classic aura, post-ictal confusion, and muscle pain indicate seizure.
  • Anemia
  • Postprandial precipitants
  • Shy-drager syndrome or secondary to amyloidosis, diabetes, Parkinson's, alcoholism.
  • SVT, VT, VF
  • Structural cardiopulmonary disease
  • Valvular heart disease
  • Aortic stenosis
  • Tricuspid stenosis
  • Mitral stenosis
  • Cardiomyopathy
  • Pulmonary hypertension
  • Congenital heart disease
  • Myxoma
  • Pericardial disease
  • Aortic dissection
  • Pulmonary embolism
  • Myocardial ischemia
  • Myocardial infarction
  • Dysrhythmias
  • Bradydysrhythmias
  • Stokes-Adams attack
  • Sinus node disease
  • Second- or third-degree heart block
  • Pacemaker malfunction
  • Tachydysrhythmias
  • Ventricular tachycardia
  • Torsades de pointes
  • Supraventricular tachycardia
  • Atrial fibrillation or flutter
  • Vasovagal
  • Situational
  • Cough
  • Micturition
  • Defecation
  • Swallow
  • Neuralgia
  • Carotid sinus syndrome
Orthostatic hypotension
  • Drug induced
  • Autonomic failure
  • Hypovolemis
  • Transient ischemic attacks
  • Subclavian steal
  • Migraine (basilar)
  • Subclavian steal syndrome
  • Vertebrobasiloar TIA
  •  Antihypertensives
  •  β-Blockers
  •  Cardiac glycosides
  •  Diuretics
  •  Antidysrhythmics
  •  Antipsychotics
  •  Antiparkinsonism drugs
  •  Antidepressants
  •  Phenothiazines
  •  Nitrates
  •  Alcohol
  •  Cocaine
Breath holding (pediatric)*
Non-Syncopal causes
  • Hypoglycemia
  • Hyperventilation
  • Seizure
  • Cataplexy
  • Drop attacks
  • Psychogenic "pseudo-syncope"


If Dizziness DOES NOT seem to be vertigo then initiate the following tests:

  1. CBC, BMP, EKG, Cardiac Enzymes, POC Glucose, .
  2. UA, UDS, POC Preg (females) [if pregnant, work up for ectopic pregnancy]
  3. PT/INR if on warfarin
  4. Consider CT-Brain, CXR, Orthostatic vitals.
  5. Hemeoccult if orthostatic
  6. Saline lock
  • History/Symptoms
    • H&P will yield diagnosis 80% of time & labs usually necessary only to confirm diagnosis
    • Sudden, transient loss of consciousness (or "near" loss) & inability to maintain postural tone
    • Event itself
      • Position: prolonged standing (likely neurocardiogenic)
      • Onset: sudden without warning or prodrome (ie, arrhythmia)
      • Duration: difficult to quantify, even if witnessed
        • > 5 min raises concern for seizure or other causes of AMS
      • Exertional syncope: consider cardiac causes
    • Age
      • Young patients often experience neurocardiogenic syncope
      • Hx of underlying heart disease is more predictive vs. age
    • Events surrounding episode
      • First vs. recurrent
      • Coughing
      • Breath-holding, hyperventilation
      • Micturition, defecation
      • Change in position
      • Exertion, arm activity
      • Post-event confusion or soreness
    • Medical history, including psychiatric and family history
    • Seizures, metabolic/toxic abnormalities (ie, hypoglycemia), anaphylaxis can mimic syncope
    • Medications
      • Cardiac, vasodilators
      • Antidepressants, phenothiazines
      • Diuretics
      • Drugs of abuse, alcohol
  • Physical exam/Signs
    • Check for injury
    • Vital signs, orthostatics (not sensitive nor specific)
      • Orthostasis: decrease in SBP by ≥ 20 mmHg or DBP ≥ 10 mmHg
    • HEENT, cardiac, respiratory, neurologic exam
    • Check for incontinence, signs of seizure
  • Patients at high risk for cardiac etiology:
    • Age > 45
    • History of ventricular dysrhythmias
    • History of congestive heart failure
    • Abnormal ECG
    • Syncope in supine position
    • Exertional syncope
    • Syncope associated with chest pain
  • Patient at low risk for cardiac etiology
    • Young patient, normal physical examination, normal ECG
    • Clinical presentation suggestive of vasovagal syncope
  • Imaging
    • Consider Head CT for
      • Trauma above clavicle
      • Persistent neurologic deficit/complaint
      • Age > 65 yo
      • Sudden onset of headache
      • On warfarin
      • Focal neurologic deficits or concern for structural brain disease
      • Holter monitoring w/ recurrent syncope of unknown cause
    • Echocardiography: To screen for underlying cardiovascular disease if diagnosis remains unclear
  • Other Tests/Criteria
    • ECG on ALL patients
    • Cardiopulmonary Monitor


Goals of Care (ED core measures) for syncope: ECG for every patient >60 years old with a discharge diagnosis of syncope from ED


ED Care and Disposition:

By definition, syncope results in spontaneous recovery of consciousness. Therefore, the main goal of ED care is to identify those pts at risk for further medical problems. Pts can be categorized into 1 of 3 classes after a careful history, physical examination, & ECG:

  1. If  the diagnosis is established (eg, pulmonary embolus, ectopic pregnancy, GI Bleed)
    • The pt can be appropriately managed by directing attention to the underlying cause of the syncopal event.
    • Pts for whom a life-threatening etiology is identified, including those with neurologic or cardiac causes, warrant admission.
  2. Pts with unclear diagnosis who are high-risk are those for whom there is concern about sudden cardiac death or ventricular dysrhythmia. As suggested by San Francisco Syncope Rule, concerning findings placing pts in the high-risk category include:
    • Abnormal ECG,
    • Complaint of  SOB,
    • sBP < 90 mm Hg on arrival,
    • Hematocrit < 30%,
    • Age > 45 yrs, or
    • Hx of ventricular dysrhythmia or CHF.

    Admissions of these pts is warranted, for observation and to facilitate expedited workup (usually focused on cardiac etiology).

  3. Pts with unclear diagnosis who are low-risk or unlikely to have a cardiac etiology for their syncope.
    • These pts lack the high-risk criteria noted above.
    • They are young (< 45 yr), have few comorbidities, and have a normal physical examination & ECG.
    • In this group, syncope is usually vasovagal & no further workup is required if the episode is isolated.
    • Low-risk pts can be safely discharged home with instructions to return for any recurrence of presyncopal symptoms.
    • Worrisome or recurrent causes may benefit from further outpt. workup including Holter or loop-event monitoring.
    • These pts should also be advised that, pending further outpt workup, they are considered at-risk for syncope & should modify behavior accordingly (eg, avoid driving).

Post ED testing for Syncope:
Test Indication Utility
Cardiac syncope
Electrocardiographic monitoring Admission Cardiac syncope confirmed if recurrent symptoms occur during monitored dysrhythmia; excluded if recurrent symptoms reported during sinus rhythm
Outpatient event monitor if no significant cardiac disease suspected
Echocardiography History, examination, or ECG suggestive of structural heart disease Confirms and quantifies suspected structural heart disease
Electrophysiology testing Documented dysrhythmia or serious underlying heart disease Identifies inducible tachydysrhythmias and some bradydysrhythmias
Stress testing Exercise-related syncope Identifies exercise-induced dysrhythmias and postexercise syncope
Neurologic syncope
CT/magnetic resonance angiography/carotid Doppler Neurologic signs or symptoms Identifies cerebrovascular abnormality or subclavian stenosis
Electroencephalography Suspected seizure Documents underlying seizure disorder
Reflex-mediated syncope
Tilt-table testing Recurrent syncope, cardiac etiology excluded Positive test establishes diagnosis of neurocardiogenic syncope
Psychiatric testing Young patient, no underlying heart disease

Admit Orders: Syncope

1. Admit to: Monitored bed

2. Diagnosis: Syncope

3. Condition:

4. Vital Signs: q1h, postural BP and pulse q12h. Call physician if BP >160/90, <90/60; P >120, <50; R>25, <10

5. Activity: Bed rest.

6. Nursing:

7. Diet: Regular

8. IV Fluids: Normal saline at TKO.

9. Special medications:

High-Grade AV Block with Syncope:

-Atropine 1 mg IV x 2.

-Isoproterenol 0.5-1 mcg/min initially, then slowly titrate to 10 mcg/min IV infusion (1 mg in 250 mL NS).

-Transthoracic pacing.

Drug-Induced Syncope:

-Discontinue vasodilators, centrally acting hypotensive agents, tranquilizers, antidepressants, and alcohol use.

Vasovagal Syncope:

-Scopolamine 1.5 mg transdermal patch q3 days.

Postural Syncope:

-Midodrine (ProAmatine) 2.5 mg PO tid, then increase to 5-10 mg PO tid [2.5, 5 mg]; contraindicated in coronary artery disease.

-Fludrocortisone 0.1-1.0 mg PO qd.

10. Symptomatic Medications:

-Acetaminophen (Tylenol) 325-650 mg PO q4-6h prn headache.

-Docusate sodium (Colace) 100-200 mg PO qhs.

11. Extras: CXR, ECG, 24h Holter monitor, tilt test, CT/MRI, EEG, 2D Echo, Carotid Doppler, +/- Stress Test.

12. Labs: CBC, CMP, Cardiac Enzymes & EKG, Mg, Phos, calcium, drug levels. UA, urine drug screen, orthostatic vitals.