367.1 🎓 醫孞生版

367.1.0.1 📌 䞀頁重點

367.1.0.1.1 Definition
  • Transient LOC
  • Due to global cerebral hypoperfusion
  • Rapid onset
  • Short duration
  • Spontaneous complete recovery
367.1.0.1.2 Etiology Categories

367.1.1 1. Reflex (Neurally Mediated) — ~ 60-70%

Vasovagal (most common): - Prodrome: warmth, nausea, diaphoresis, blurred vision - Triggers: emotion, pain, prolonged standing, heat - Slow onset → fall → wakes up rapidly

Situational: - Cough, micturition, defecation, deglutition, post-exercise, post-prandial

Carotid sinus syndrome: - Older - Shaving, tight collar, head turning - Carotid sinus hypersensitivity

367.1.2 2. Orthostatic — ~ 15%

Drug-induced: - Antihypertensives (especially α-blockers, vasodilators, diuretics) - Antidepressants (TCAs) - Antipsychotics - Antiparkinsonian

Volume depletion: - Dehydration - Hemorrhage - Adrenal insufficiency

Autonomic failure: - Primary (PD, MSA, pure autonomic failure, dementia with LB) - Secondary (diabetes, amyloidosis, paraneoplastic)

367.1.3 3. Cardiac — ~ 10-15% (MOST CONCERNING)

Arrhythmia: - Bradycardia (SSS, AV block) - Tachycardia (VT, SVT, AF/flutter) - Pacemaker malfunction - Inherited (long QT, Brugada, CPVT, ARVC, HCM)

Structural: - Severe AS - HCM with obstruction - PE (massive) - AMI - Cardiac tamponade - Aortic dissection - Atrial myxoma - Pulmonary hypertension

367.1.3.0.1 History (Key Diagnostic)

367.1.4 Typical Vasovagal

  • Prodrome (warmth, sweat, nausea, vision changes)
  • Trigger
  • Standing or emotional context
  • Pallor, sweating
  • Brief LOC (seconds-minute)
  • Quick recovery
  • May have brief myoclonic jerks

367.1.5 Typical Cardiac

  • Sudden without prodrome
  • During exertion
  • Palpitations
  • Family history sudden death
  • Known cardiac disease
  • Recovery may be delayed

367.1.6 Typical Orthostatic

  • Standing up
  • Medication context
  • Volume depletion

367.1.7 Distinguish from Seizure

  • Aura (more specific) vs prodrome
  • Tonic-clonic (vs brief myoclonic)
  • Lateral tongue bite (specific)
  • Post-ictal confusion (minutes)
  • Incontinence (less specific)
367.1.7.0.1 Examination

367.1.8 Vital Signs

  • Orthostatic BP + HR:
    • Supine → standing
    • Measure at 1 + 3 min
    • Positive: SBP ↓ ≥ 20, DBP ↓ ≥ 10, or HR ↑ > 20 (POTS)

367.1.9 Cardiac Exam

  • Murmurs (AS, HCM, MS)
  • Carotid bruit
  • Volume status

367.1.10 Neuro

  • Focal deficits (vertebrobasilar TIA differential)
  • Lateral tongue bite

367.1.11 Carotid Sinus Massage

  • Older patient with unexplained syncope
  • After excluding bruit/recent stroke
  • Continuous ECG monitoring
  • Hypersensitivity: > 3 sec pause or > 50 mmHg BP drop
367.1.11.0.1 Workup

367.1.12 Initial Tests (All Syncope)

  • ECG (mandatory!) — look for:
    • Prolonged QT (LQTS)
    • Brugada pattern
    • Pre-excitation (WPW)
    • Heart block
    • HCM
    • Old MI
    • ARVC features
  • Glucose, electrolytes, Hb (selected)
  • Pregnancy test (selected)

367.1.13 Additional Based on Suspicion

  • Echocardiogram: structural disease suspected
  • Tilt table: recurrent unexplained, suspected reflex
  • Holter / loop recorder: arrhythmia suspected
  • Implantable loop recorder (ILR): recurrent unexplained syncope
  • EP study: structural disease + arrhythmia
  • Stress test: exertional syncope
  • Cardiac MRI: ARVC, cardiomyopathy, sarcoidosis
  • CT chest: PE if appropriate
  • Genetic testing: family history, LQTS, Brugada, HCM

367.1.14 Imaging

  • Routine CT head NOT useful unless trauma or focal deficit
367.1.14.0.1 Risk Stratification

367.1.15 San Francisco Syncope Rule (SFSR)

  • CHESS: CHF, Hct < 30, ECG abnormal, SOB, SBP < 90
  • Any present = high risk

367.1.16 OESIL

  • Age > 65, CV history, syncope without prodrome, abnormal ECG
  • Score 0-4

367.1.17 EGSYS

  • Predicts cardiac syncope

367.1.18 High-Risk Features (Admit)

  • Cardiac suspected
  • Abnormal ECG
  • Known/suspected structural heart disease
  • Family history sudden death
  • Exertional
  • Recent palpitations
  • Severe injury
  • ↑ troponin
367.1.18.0.1 Treatment

367.1.19 Reflex (Vasovagal)

  • Reassurance + education
  • Avoid triggers
  • Adequate hydration
  • Counter-pressure maneuvers (squat, leg crossing)
  • Tilt training
  • Refractory: midodrine, fludrocortisone
  • Severe + dominant bradycardia: pacemaker (selected)

367.1.20 Orthostatic

  • Treat cause
  • Adequate fluid + salt
  • Compression stockings
  • Midodrine (α1 agonist)
  • Fludrocortisone (mineralocorticoid)
  • Pyridostigmine for neurogenic OH
  • Droxidopa (Northera) for neurogenic OH (PD, PAF, MSA)
  • Adjust offending medications

367.1.21 Cardiac

  • Pacemaker for bradycardia, AV block
  • ICD for VT, structural disease, channelopathies with high risk
  • AS → AVR (TAVR or surgical)
  • HCM → β-blocker, disopyramide, septal reduction (myectomy or alcohol ablation), ICD
  • Treat underlying (AMI, PE, etc.)
  • Channelopathies (LQTS, Brugada): β-blocker, ICD, avoid triggers

367.1.21.1 🩺 床邊速查

  • Three categories: reflex (vasovagal most common) > orthostatic > cardiac (most concerning)
  • ECG mandatory for all syncope
  • Echocardiogram if structural disease suspected
  • Orthostatic vitals: SBP ↓ ≥ 20, DBP ↓ ≥ 10, HR ↑ > 20 (POTS)
  • High-risk admit: cardiac suspected, abnormal ECG, structural disease, exertional, FHx sudden death
  • Vasovagal Tx: reassurance + education + hydration + counter-pressure
  • Cardiac Tx: pacemaker / ICD / AVR / specific treatment