Cardiovascular Medicine Book

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SyncopeAka: Near-syncope, Presyncope

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  1. See Also
    1. Vasovagal Syncope
    2. Cardioinhibitory Syncope
    3. Vasodepressor Syncope
    4. San Francisco Syncope Rule
  2. Definition
    1. Rapid onset of transient loss of consciousness
    2. May be associated with a fall
    3. Resolves spontaneously and quickly
  3. Background
    1. Up to one third of syncope cases are idiopathic
    2. Common diagnosis
      1. Occurs in up to 50% of adults, and 75% over age 75
      2. Accounts for up to 3% of ER visits, 6% of admissions
  4. Pathophysiology
    1. Decreased cerebral perfusion (usually on standing)
  5. Causes: Non-Cardiac Causes (57%)
    1. Reflex Mediated Syncope (no cardiovascular risk)
      1. Vasovagal Syncope (Vasodepressor Syncope)
      2. Situational syncope
        1. Micturition syncope or with Defecation
        2. Cough syncope (or sneezing)
        3. Valsalva (brass instrument playing, weight lifting)
        4. Hyperventilation
      3. Carotid Sinus Syncope
      4. Glossopharyngeal neuralgia (uncommon)
        1. Syncope occurs with swallowing, talking, sneezing
      5. Trigeminal Neuralgia
    2. Medication-related syncope
      1. Antihypertensive Medications (e.g. Beta Blocker)
      2. Ophthalmic Beta Blockers
      3. Antianginal medications (e.g. Nitroglycerin)
      4. Digitalis
        1. Atrioventricular Block
        2. Ventricular Tachycardia
      5. Antiarrhythmic medications (esp. Type Ia)
      6. Diuretics
        1. Hypokalemia
        2. Hypomagnesemia
        3. Hypovolemia
      7. Adriamycin
      8. Phenothiazines
      9. Tricyclic Antidepressants
    3. Recreational drug use
      1. Alcohol
      2. Ecstasy (MDMA)
      3. Methamphetamine
    4. Orthostatic Syncope (2-24%)
      1. See Orthostatic Hypotension
    5. Neurologic Causes (9% of causes)
      1. Transient Ischemic Attacks: 1-7%
      2. Seizure disorder: 2%
  6. Causes: Cardiovascular (10-30% of causes)
    1. Arrhythmia
      1. Ventricular Tachycardia
      2. Sick Sinus Syndrome
      3. Supraventricular Tachycardia
      4. Atrioventricular Block (second or third degree)
      5. Pacemaker malfunction
    2. Aortic Stenosis
    3. Mitral Stenosis
    4. Myocardial Infarction
    5. Aortic Dissection
    6. Pulmonary Embolism
    7. Pulmonary Hypertension
    8. Subclavian Steal Syndrome
    9. Hypertrophic Cardiomyopathy
    10. Atrial myxoma
  7. History: Predisposing Conditions
    1. Family History of Sudden Cardiac Death (e.g. SADS)
    2. Diabetes Mellitus (Hypoglycemia)
    3. Parkinson's Disease (Orthostatic Hypotension)
    4. Seizure Disorder
  8. History: Preceeding or provocative event
    1. Prolonged standing (e.g. Vasovagal Syncope)
    2. Immediately on standing (Orthostatic Hypotension)
    3. With exertion (Cardiomyopathy, CAD, Valve stenosis)
    4. After exertion in an athlete (Vasovagal Syncope)
    5. Valsalva (cough, swallowing, urinating or stooling)
      1. Reflex-mediated syncope
    6. Neck rotation or pressure (e.g. tight collar)
      1. Carotid Sinus Hypersensitivity
    7. Use of arms (Subclavian Steal Syndrome)
    8. Stressful event (Vasovagal Syncope)
  9. History: Associated symptoms during event
    1. Nausea, chills and sweats (Vasovagal Syncope)
    2. Aura (Migraine Headache, Seizure Disorder)
    3. Slumping (Coronary Artery Disease, arrhythmia)
    4. Kneeling (Orthostatic Hypotension)
    5. Brief loss of consciousness (arrhythmia)
    6. Loss of consciousness >5 minutes
      1. Neurologic, metabolic, or infectious cause
    7. Tonic-clonic movements
      1. Movements occur before fall (Seizure disorder)
      2. Movements occur after fall (Vasovagal Syncope)
    8. Chest Pain (CAD, PE, Aortic Dissection)
    9. Palpitations (Arrhythmia)
    10. Incontinence of urine or stool (Seizure)
  10. Signs
    1. General
      1. Pallor (Orthostatic Hypotension due to Anemia)
      2. Tongue bitten (Seizure)
    2. Cardiovascular examination
      1. Carotid Bruits
      2. Heart Murmur
      3. Asymmetric pulses
      4. Carotid massage
        1. Avoid in Cerebrovascular Disease or Carotid Bruit!
    3. Neurologic Exam
      1. Post-event Confusion (Seizure Disorder)
      2. Focal neurologic deficit
  11. Differential Diagnosis
    1. Vertigo (no loss of consciousness)
    2. Drop Attacks (No loss of consciousness, no aura)
    3. Seizure
  12. Labs and diagnostic testing: Initial evaluation
    1. Serum electrolytes including glucose
    2. Hemoglobin or Hematocrit
    3. Electrocardiogram
      1. See Electrocardiogram in Syncope
    4. Chest XRay
    5. Brain Natriuretic Peptide (BNP)
      1. BNP > 40 pg/ml strongly suggests cardiac cause
      2. Test Sensitivity: 82%
      3. Test Specificity: 92%
      4. Tanimoto (2004) Am J Cardiol 93:228
    6. Additional tests to strongly consider
      1. Serial Troponin I and inpatient telemetry monitoring
      2. Cardiac stress testing
      3. Event Monitor or Holter Monitor
      4. Echocardiogram
  13. Reassuring findings suggestive of neurally-mediated cause
    1. No cardiac history
    2. Chronic history of syncope
    3. Triggered by specific stimulus
      1. Noxious smell, sound, sight or pain
      2. Prolonged standing, crowded place, heat
      3. Nausea or Vomiting
      4. Post-meal
      5. Rotation of head or tight collar, shaving
      6. Post-exertion
  14. Hospitalization Indications
    1. Syncopal episode occurring during Exercise
    2. Family History of sudden death
    3. Severe Orthostatic Hypotension
    4. Suspected underlying serious cause
      1. Coronary Artery Disease
      2. Cardiac arrhythmia
      3. Cerbebrovascular accident
    5. References
      1. Brignole (2001) Eur Heart 22:1256
  15. Prognosis
    1. See San Francisco Syncope Rule
      1. Predicts short-term risk of serious outcome
    2. Mortality 10% within 6 months of cardiovascular syncope
      1. Soteriades (2002) N Engl J Med 347:878
  16. References
    1. Kapoor (2000) N Engl J Med 343:1856
    2. Brignole (2001) Eur Heart J 22:1256
    3. Miller (2005) Am Fam Physician 72:1492

Syncope (C0039070)

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.
Definition (NCI)Extremely weak; threatened with syncope.
Definition (NCI)Extremely weak; threatened with syncope.
Definition (NCI)A spontaneous loss of consciousness caused by insufficient blood to the brain.
ConceptsSign or Symptom (T184)
ICD9780.2
DanishKortvarigt bevidsthedstab/synkope
DutchFlauwvallen/syncope
EnglishA faint, COLLAPSE FLEETING, COLLAPSE TRANSIENT, FAINT, Faint symptom, Fainted, FAINTING, FAINTING EPISODES, Fainting/syncope, Faintness, FALLING OUT, PASSED OUT, SWOONING, Syncope, Syncope and collapse, Syncope attack, Syncope symptom, Syncopes
FinnishPYORTYMINEN
FrenchEvanouissement/syncope
GermanKollaps/Ohnmacht/Synkope
Hebrewhitalfut
Hungarianajulas/eszmeletvesztes
ItalianSvenimento/sincope
PortugueseDesmaio/sincope
Spanishdesmayo, Desmayo/sincope, desvanecimiento, síncope, síncope y colapso, sincope, sincope y colapso
SwedishSVIMNING
CreditsDerived from the NIH UMLS (Unified Medical Language System)


Presyncope (C0700200)

ConceptsSign or Symptom (T184)
EnglishNear syncope, Presyncope, Presyncopes
CreditsDerived from the NIH UMLS (Unified Medical Language System)



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