II. Definition
- Syncope
- Rapid onset of transient loss of consciousness
- May be associated with a fall
- Resolves spontaneously and quickly without intervention
- Presyncope
- Weakness, Dizziness, light headedness or "graying out" of consciousness without loss of postural tone
- Evaluated as Syncope with same risks of adverse event
III. Background
- Up to one third of Syncope cases are idiopathic
- Common diagnosis
- Occurs in up to 50% of adults, and 75% over age 75
- Accounts for up to 3% of ER visits, 6% of admissions
- Precautions
- Careful history, exam, and ekg should direct limited diagnostics and disposition
- Always consider serious cause differential diagnosis (see rule of 15s below)
IV. Pathophysiology
- Decreased global cerebral perfusion (usually on standing)
V. Risk Factors
- Elderly
- Structural heart disease (e.g. Aortic Stenosis)
- Congestive Heart Failure
- Coronary Artery Disease
VI. Causes: Non-Cardiac Causes (57%)
-
Reflex Mediated Syncope (no cardiovascular risk, most common)
- Vasovagal Syncope (Vasodepressor Syncope)
- Situational Syncope
- Micturition Syncope or with Defecation
- Cough Syncope (or sneezing)
- Valsalva (brass instrument playing, weight lifting)
- Hyperventilation
- Carotid Sinus Syncope
- Glossopharyngeal neuralgia (uncommon)
- Syncope occurs with swallowing, talking, sneezing
- Trigeminal Neuralgia
- Medication-related Syncope
- Antihypertensive Medications (e.g. Beta Blocker)
- Ophthalmic Beta Blockers
- Antianginal medications (e.g. Nitroglycerin)
- Digitalis
- Antiarrhythmic medications (esp. Type Ia)
- Diuretics
- Hypokalemia
- Hypomagnesemia
- Hypovolemia
- Adriamycin
- Phenothiazines
- Tricyclic Antidepressants
- Recreational drug use
- Orthostatic Syncope (2-24%)
- Neurologic Causes (9% of causes)
- Transient Ischemic Attacks: 1-7%
- Seizure disorder: 2%
VII. Causes: Cardiovascular (10-30% of causes, high risk conditions)
- Predisposing cardiac conditions
- Arrhythmias
- Ventricular Tachycardia
- Sick Sinus Syndrome
- Supraventricular Tachycardia
- Atrioventricular Block (second or third degree)
- Pacemaker malfunction
- Valvular disorders
- Hypertrophic Cardiomyopathy (esp. young patients)
- Aortic Stenosis
- Acute Mitral Valve Regurgitation (i.e. acute MI with papillary muscle rupture)
- Prosthetic Heart Valve complication (e.g. Thromboembolism, valvular obstruction)
- Vascular disorders
- Myocardial disorders
- Hypertrophic Cardiomyopathy
- Atrial myxoma
VIII. Causes: Syncope-Plus
- Subset of patients present with Syncope Plus another key symptom
- Acute Painful Syncope
IX. History: Predisposing Conditions
- Family History of Sudden Cardiac Death (e.g. SADS)
- Diabetes Mellitus (Hypoglycemia)
- Parkinson's Disease (Orthostatic Hypotension)
- Seizure Disorder
- Dehydration or blood loss
- Psychiatric illness
- Anxiety Disorder
- Panic Attack
- Hypoventilation
X. History: Preceeding or provocative event
- Prolonged standing
- Immediately on standing
- While lying supine
- Cardiovascular Syncope (higher risk)
- With exertion (high risk for serious cause)
- See Exertional Syncope
- Aortic Stenosis
- Coronary Artery Disease or Coronary Artery Abnormalities
- Cardiomyopathy (e.g. Hypertrophic Cardiomyopathy, Myocarditis)
- Arrhythmia (e.g. ARVD, Long QT Syndrome, WPW Syndrome, Brugada Syndrome)
- Miscellaneous Causes (e.g. Heat Stroke, Hypoglycemia, Hyponatremia)
- After exertion in an athlete
- Valsalva (cough, swallowing, urinating or stooling)
- Reflex-mediated Syncope
- Neck rotation or pressure (e.g. tight collar)
- Use of arms
- Stressful event
XI. History: Associated symptoms during event
- Nausea, chills and sweats
- Aura
- Migraine Headache
- Seizure Disorder
- No prodromal symptoms (see below)
- Cardiovascular Syncope (higher risk)
- Slumping
- Coronary Artery Disease
- Arrhythmia
- Kneeling
- Brief loss of consciousness
- Arrhythmia
- Loss of consciousness >5 minutes
- Neurologic, metabolic, or infectious cause
- Tonic-clonic movements
- Seizure disorder
- Movements occur before fall and last longer than 30 seconds
- Followed by postictal period of confusion
- Vasovagal Syncope
- Movements occur after fall, and appear as myoclonic jerks
- Seizure disorder
- Focal neurologic deficits
- TIA or CVA (although LOC requires significant CNS involvement, for which resolution would be delayed)
- Todd's Paralysis (Seizure)
- Severe Thunderclap Headache
- Chest Pain
-
Palpitations
- Arrhythmia
-
Incontinence of urine or stool
- Seizure Disorder
- Severe Abdominal Pain or back pain
- Pelvic Pain or Vaginal Bleeding
XII. Symptoms: Prodromal
- Dizziness
- Vision Loss
- Hearing Loss
- Sensation loss
- Weakness
- Diaphoresis
- Palpitations
XIII. Exam
-
Vital Signs
- Temperature
- Blood Pressure
-
Orthostatic Blood Pressure (low yield)
- Frequently abnormal in healthy subjects and a majority of the elderly
- However, in elderly, Orthostatic Hypotension may alter disposition and management
- Evaluate patient for symptoms reproduced on standing (more important than measurements)
-
General
- Pallor
- Orthostatic Hypotension due to Anemia
- Tongue bitten
- Ear Exam
- Dix-Hallpike Maneuver
- Pallor
- Cardiovascular examination
- Carotid Bruits
- Heart Murmur (evaluate new murmurs associated with Syncope)
- Asymmetric Pulses
- Carotid massage (rarely performed)
- Avoid in Cerebrovascular Disease or Carotid Bruit!
-
Neurologic Exam
- Post-event Confusion (Seizure Disorder)
- Focal neurologic deficit
- Perform a careful Neurologic Exam to identify subtle deficits
- Red flags suggestive of ongoing active cardiovascular or Syncope-plus cause
- Diaphoresis
- Tachycardia
- Dyspnea
- Significant pain
- Evaluate for injury related to syncopal fall
- See Trauma Evaluation
- Exclude head or neck injury
- Exclude extremity injury
XIV. Differential Diagnosis: Serious Causes
- Arrhythmia
- May be mis-diagnosed as Seizure
- Wolff-Parkinson-White Syndrome (WPW Syndrome)
- Brugada Syndrome
- Prolonged QTc >500 ms
- Ventricular Tachycardia
- Structural heart defects and vascular conditions
- Hypertrophic Cardiomyopathy (esp. young patients)
- Aortic Stenosis
- Acute Mitral Valve Regurgitation
- Typically from acute Myocardial Infarction with papillary muscle rupture
- Prosthetic Heart Valve complication (e.g. Thromboembolism, valvular obstruction)
- Acute catastrophic disorders (Rule of 15s: Each condition has a 15% Incidence as syncopal presentation)
XV. Differential Diagnosis: Other causes
XVI. Labs
- Basic Chemistry Panel (Serum electrolytes including Glucose)
- Low yield in young patients (age <40 years old) without other risk factors
- Bedside Glucose alone may be sufficient in these patients
- Patients warranting chemistry panel
- Patients over age 40 years old
- Prolonged QTc (include Serum Magnesium, Serum Calcium, Serum Potassium)
- Gastrointestinal losses (Vomiting or Diarrhea)
- Diabetes Mellitus
- Chronic Kidney Disease
- Diuretic use
- Dietary restrictions
- Low yield in young patients (age <40 years old) without other risk factors
-
Hemoglobin or Hematocrit
- Obtain for blood loss (e.g. Menorrhagia, GI Bleed), comorbidity (HIV, cancer, Renal Failure) or signs (pallor, weakness)
-
Pregnancy Test (urine HCG)
- Consider in Abdominal Pain, Vaginal Bleeding in patients of child bearing age
-
Fecal Occult Blood Test
- Consider in cases of Anemia or associated gastrointestinal symptoms
-
Troponin I
- Associated with a significantly worse outcome if elevated
- However Syncope is a rarely due to ACS or Myocardial Infarction (3% of cases)
- Arrhythmia is a more likely cause of Syncope
- Troponin Is positive in only 1.4% of Syncope patients
- Patients with Syncope due to ACS/MI should still appear ill at evaluation
- Indications
- Chest Pain, Shortness of Breath or other cardiopulmonary symptoms
- EKG with ischemic changes
- References
-
Brain Natriuretic Peptide (BNP)
- Non-specific and unlikely to affect management or disposition
- Earlier studies demonstrated an association with cardiac cause of Syncope
- Other labs to consider
- D Dimer (if Pulmonary Embolism is suspected)
XVII. Diagnostics
-
Electrocardiogram (EKG)
- See Electrocardiogram in Syncope
- Obtain in all Syncope patients
- However, significant findings in only 5% overall, and 0-3% in those under age 40 years old
- Identify VT, Brugada Syndrome, WPW (short PR), Prolonged QTc >500, Hypertrophic Cardiomyopathy, ischemia
- May assist in distinguishing Seizure and Syncope
- EKG is low yield in syncopal patients under age 40 years old
- Additional tests to consider
- Cardiac stress testing
- Event Monitor or Holter Monitor
XVIII. Imaging: General
-
Chest XRay
- Low yield test (positive in <0.6% of Syncope patients)
- Abnormal findings (e.g. mediastinal widening, Pneumonia, Pneumothorax) are unlikely without physical findings
- Obtain if Chest Pain, Dyspnea, increased Respiratory Rate or Hypoxia
-
Echocardiogram
- Consider in suspected acute valvular cause of Syncope (especially if associated with new murmur)
- Consider if status-post prosthetic Valve Replacement (evaluate for significant valvular dysfunction, obstruction)
- Evaluate for Hypertrophic Cardiomyopathy (HOCM), Aortic Stenosis, MI with acute Mitral Regurgitation
- Other imaging to consider
- CT chest with contrast (if Pulmonary Embolism is suspected)
- Imaging related to injuries sustained in a Syncope-related fall
XIX. Imaging: CT Head
- Efficacy: Low
- Head CT is very low yield in Syncope and not recommended unless indications below
- Goyal (2001) Intern Emerg Med 1(2):148-50 [PubMed]
- Grossman (2007) Intern Emerg Med 2(1):46-9 +PMID:17551685 [PubMed]
- Indications
- Trauma above the clavicles
- Persistent neurologic deficit
- Dizziness
- Sudden onset Headache (Thunderclap Headache of Subarachnoid Hemorrhage)
- Age over 65 years
- Warfarin use
- First Seizure
XX. Evaluation: Reassuring findings suggestive of neurally-mediated cause
XXI. Management: Hospitalization Indications
- Abnormal San Francisco Syncope Rule (CHESS Criteria)
- Syncopal episode occurring during Exercise
- Family History of sudden death
- Severe Orthostatic Hypotension
- Abnormal Vital Signs
- Hematocrit <30%
- Advanced age
- Congestive Heart Failure (or other structural heart disease)
- Abnormal Electrocardiogram, including Prolonged QTc >500 ms (risk of Torsades de Pointes)
- Syncope WITHOUT prodrome
- Arrhythmia is more likely if absent prodrome (e.g. vision dimming, light headedness, Nausea, diaphoresis)
- Suspected underlying serious cause
- Coronary Artery Disease
- Cardiac arrhythmia
- Cerbebrovascular accident (does not typically result in Syncope, see above)
- References
XXII. Prognosis
- See San Francisco Syncope Rule (CHESS Criteria)
- Predicts short-term risk of serious outcome
- Mortality 10% within 6 months of cardiovascular Syncope
XXIII. References
- Joshi and Dermark (2016) Crit Dec Emerg Med 30(8):3-12
- Orman and Mattu in Herbert (2016) EM:Rap 16(3): 9-11
- Schauer et al. (2016) Crit Dec Emerg Med 30(9):13-9
- Kapoor (2000) N Engl J Med 343:1856-62 [PubMed]
- Brignole (2001) Eur Heart J 22:1256-306 [PubMed]
- Miller (2005) Am Fam Physician 72:1492-500 [PubMed]
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| Definition (MEDLINEPLUS) |
Fainting is a temporary loss of consciousness. If you're about to faint, you'll feel dizzy, lightheaded, or nauseous. Your field of vision may "white out" or "black out." Your skin may be cold and clammy. You lose muscle control at the same time, and may fall down. Fainting usually happens when your blood pressure drops suddenly, causing a decrease in blood flow to your brain. It is more common in older people. Some causes of fainting include
When someone faints, make sure that the airway is clear and check for breathing. The person should stay lying down for 10-15 minutes. Most people recover completely. Fainting is usually nothing to worry about, but it can sometimes be a sign of a serious problem. If you faint, it's important to see your health care provider and find out why it happened. |
| Definition (NCI) | A spontaneous loss of consciousness caused by insufficient blood supply to the brain. |
| Definition (NCI_CTCAE) | A disorder characterized by spontaneous loss of consciousness caused by insufficient blood supply to the brain. |
| Definition (NCI_FDA) | Extremely weak; threatened with syncope. |
| Definition (NCI_CDISC) | Sudden loss of consciousness with loss of postural tone, not related to anesthesia, with spontaneous recovery as reported by patient or observer. A subject may experience syncope when supine. Syncope is often caused by insufficient blood supply to the brain. |
| Definition (NCI) | Extremely weak; threatened with syncope. |
| Definition (MSH) | A transient loss of consciousness and postural tone caused by diminished blood flow to the brain (i.e., BRAIN ISCHEMIA). Presyncope refers to the sensation of lightheadedness and loss of strength that precedes a syncopal event or accompanies an incomplete syncope. (From Adams et al., Principles of Neurology, 6th ed, pp367-9) |
| Definition (CSP) | fainting due to a sudden fall of blood pressure below the level required to maintain oxygenation of brain tissue. |
| Concepts | Sign or Symptom (T184) |
| MSH | D013575 |
| ICD9 | 780.2 |
| ICD10 | R55 |
| SnomedCT | 206727002, 206725005, 206731008, 271594007, 271211004, 29423006, 158137001, 158135009, 271785004, 158133002, 139532000, 162263008, 309585006, 272030005 |
| LNC | MTHU020851, LA16987-2 |
| English | Fainting, Syncope, Syncopes, COLLAPSE TRANSIENT, FAINTNESS, FALLING OUT, Fainted, PASSED OUT, SWOONING, Syncope and collapse NOS, [D]Syncope, [D]Syncope and collapse, [D]Syncope and collapse NOS, A faint, Passed out, [D]Fainting (context-dependent category), [D]Syncope and collapse (context-dependent category), [D]Syncope and collapse NOS (context-dependent category), [D]Fainting, fainting (syncope), syncope, fainting, fainting (symptom), Syncopal attack, Falling out, Swooning, Faint, Syncope [Disease/Finding], attacks syncopal, disorders syncope, fainting episodes, falls out, Attack(s);fainting, collapse syncope, faint, fainted, faints, syncope attack, out pass, pass out, attacks fainting, out passed, syncopes, fainting/syncope, Swoon, syncope fainting, faintness, swoons, out passes, swooning, passed out, syncope collapse, fainting syncope, [D]: [fainting] or [collapse] (disorder), [D]Syncope and collapse NOS (situation), Syncope (finding), [D]: [fainting] or [collapse] (situation), [D]Syncope and collapse (situation), [D]Fainting (situation), Fainting (finding), Fainting [D], Faint symptom, [D]: [fainting] or [collapse], SYNCOPE, FAINT, FAINTING, Syncope and collapse, Syncope symptom, Syncope attack, Syncope (disorder), Syncope and collapse (disorder), Syncope symptom (disorder), Fainting/syncope, attack; syncope, attack; unconsciousness, collapse; general, fainting; fit, fit; fainting, general; collapse, loss of consciousness; attack, syncope; syncope, unconsciousness; attack, Syncope, NOS, Faintness, Collapse fleeting, Collapse transient, fainting attacks, swoon |
| French | SYNCOPE, Collapsus passager, Tendance lipothymique, Syncope et collapsus, Evanouissements, Collapsus transitoire, Chutes fréquentes, Pâmoison, Lipothymie, COLLAPSUS TRANSITOIRE, DECES, ETAT SYNCOPAL, EVANOUISSEMENT, PERTE DE CONNAISSANCE, A perdu connaissance, Syncope, Évanouissement |
| Portuguese | SINCOPE, DESMAIO, SÃncope e colapso, Ataque de sÃncope, Colapso transitório, Esvaimento, Perda de consciência, Desmaiado, Colapso passageiro, COLAPSO TRANSITORIO, DEBILIDADE, DESFALECIMENTO, DESMAIADO, Desmaio, SÃncope |
| Spanish | DESVANECIMIENTO, SINCOPE, DESMAYO, Colapso transitorio, Desfallecimiento, Episodio sincopal, SÃncope y colapso, Privación de sentido, AlferecÃa, Pérdida de conocimiento, Desvanecimiento, Colapso fugaz, [D]desvanecimiento (categorÃa dependiente del contexto), [D]sÃncope y colapso (categorÃa dependiente del contexto), [D]sÃncope y colapso SAI (categorÃa dependiente del contexto), CAIDA, COLAPSO TRANSITORIO, DESFALLECIMIENTO, desvanecimiento, desvanecimiento (hallazgo), [D]sÃncope y colapso SAI, [D]desvanecimiento (situación), sÃncope (hallazgo), [D]sÃncope y colapso SAI (situación), [D]sÃncope y colapso (situación), [D]desvanecimiento, [D]sÃncope y colapso, desmayo, sÃncope (trastorno), sÃncope - sÃntoma (trastorno), sÃncope - sÃntoma, sÃncope y colapso (trastorno), sÃncope y colapso, sÃncope, Desmayo, SÃncope |
| German | SYNKOPE, ohnmaechtig, Kollaps fluechtig, synkopale Attacke, bewusstlos werden, Synkope und Kollaps, Kollaps voruebergehend, schwummrig, ohnmaechtig werden, Ohnmachtsanfall, BEWUSSTLOSIGKEIT FLUECHTIG, KOLLAPS KURZDAUERND, OHNMACHT, OHNMAECHTIG WERDEN, SCHWAECHEANFALL, Ohnmacht, Synkope |
| Dutch | kortdurende collaps, flauwte, flauw, flauwteaanval, flauwvallen, voorbijgaande collaps, syncope en collaps, uitvallen, flauwgevallen, aanval van syncope, Flauwvallen/syncope, aanval; bewusteloosheid, aanval; syncope, algemeen; collaps, bewusteloosheid; aanval, bewustzijnsverlies; aanval, collaps; algemeen, flauwvallen; toeval, syncope; aanval, toeval; flauwvallen, Syncope en collaps, syncope, Collaps, Flauwvallen, Syncope |
| Italian | Attacco sincopale, Sfaldarsi, Sincope e collasso, Collasso transitorio, Malore, Svenuto, Svenimento, Sincope |
| Japanese | �倒, 一�性虚脱, 浮動性���感, 失神発作, シッシ�, イッカセイキョダツ, ソットウ, シッシ�ホッサ, フドウセイメ�イカ�, キゼツ, 脳貧血, 気絶, 失神 |
| Swedish | Svimning |
| Czech | synkopa, Tranzientnà kolaps, Synkopický záchvat, OmdlÃvajÃcÃ, Mdloba, Synkopa a kolaps, Synkopa, Výpadek, Upadnout do bezvÄ›domÃ, Pocit závratÄ›, mdloba |
| Finnish | Pyörtyminen |
| Russian | SINKOPE, OBMOROK, OBMOROK POSTURAL'NYI, POTERIA SOZNANIIA, PREDOBMOROCHNOE SOSTOIANIE, ОБМОРОК, ПОТЕРЯ СОЗ���ИЯ, ОБМОРОК ПОСТУР�ЛЬ�ЫЙ, ПРЕДОБМОРОЧ�ОЕ СОСТОЯ�ИЕ, СИ�КОПЕ |
| Korean | ì‹¤ì‹ ë°� 허탈 |
| Croatian | SINKOPA |
| Polish | Zapaść, Omdlenie |
| Hungarian | �jult, Syncopés roham, Syncope és collapsus, �tmeneti collapsus, �julásérzés, Múló collapsus, Syncope, �julás, Elájulás, Összeesés |
| Norwegian | Synkope, Besvimelse |
Ontology: Presyncope (C0700200)
| Definition (NCI) | An episode of lightheadedness and dizziness which may precede an episode of syncope. |
| Definition (NCI_CTCAE) | A disorder characterized by an episode of lightheadedness and dizziness which may precede an episode of syncope. |
| Concepts | Sign or Symptom (T184) |
| MSH | D013575 |
| SnomedCT | 427461000 |
| English | PRE-SYNCOPE, Pre-syncope, Near syncope (disorder), Near syncope, Presyncopes, near syncope, presyncope, pre-syncope, pre syncope, Presyncope |
| Dutch | presyncope, bijna-syncope, Presyncope |
| French | Syncope rattrapée, Malaise, Présyncope, LIPOTHYMIE |
| German | Praesynkope, Beinahe-Synkope, Präsynkope, PRAE-SYNKOPE |
| Italian | Semisincope, Lipotimia, Pre-sincope, Presincope |
| Portuguese | Pré-sÃncope, Quase sÃncope, Pré-SÃncope, PRE-SINCOPE |
| Spanish | Estado presincopal, casi sÃncope (trastorno), casi sÃncope, PresÃncope, PRE-SINCOPE |
| Japanese | 失神寸��状態, シッシ�ス�ゼ�ノジョウタイ |
| Czech | Presynkopa, BlÃzko synkopy, presynkopa, presynkopálnà aura |
| Hungarian | Presyncope, Praesyncope |
| Norwegian | Nærbesvimelse, Presynkope |

