Watch 👉 Syncope
- Video
See the Table below for differential diagnosis.
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Important non-syncopal mimics of syncope
| Etiology | Clinical Clues |
|---|---|
| Reflwx Syncope | |
| Vasovagal or Neurally Mediated Syncope | 🔹 Triggers → Prolonged standing emotional stress painful stimuli |
| 🔹 Prodrome → Nausea, warmth and diaphoresis | |
| Situational Syncope | 🔹 Triggers → Cough micturition defecation swallow |
| Carotid Hypersensitivity | 🔹 Tactile stimulation of carotid sinus while standing |
| 🔹 Advanced age carotid atherosclerosis | |
| Orthostatic Syncope | 🔹 Postural changes in heart rate or blood pressure after standing suddenly |
| Medications | 🔹 Vasodilators → Alpha-1 blockers antihypertensives |
| 🔹 Inotropic/chronotropic blockade → Beta blockers | |
| Hypovolemia | 🔹 History consistent with volume loss |
| Autonomic Dysfunction | 🔹 Advanced age |
| 🔹 Predisposing disease → DM & Parkinson | |
| Cardiac Syncope | |
| Aortic Stenosis HCM Anomalous Coronary Arteries | 🔹 Syncope with exertion or during exercise |
| LV Outflow Obstruction | 🔹 Syncope with exertion |
| 🔹 Systolic ejection murmur | |
| Ventricular Arrhythmias | 🔹 Prior history of CAD MI cardiomyopathy or ↓ EF |
| Ventricular Tachycardia | 🔹 No warning symptoms |
| 🔹 Cardiomyopathy or ischemic heart disease | |
| 🔹 QT-interval prolongation | |
| Sick Sinus Syndrome Bradyarrhythmias AV Block | 🔹 Sinus pauses ↑ PR or QRS duration |
| Conduction Impairment | 🔹 Preceding fatigue or light-headedness |
| 🔹 ECG abnormalities → Sinus pauses dropped QRS | |
| Torsades de Pointes (Acquired Long QT Syndrome) | 🔹 Hypokalemia & hypomagnesemia |
| 🔹 Medications causing ↑ QT interval | |
| Congenital Long QT Syndrome | 🔹 Family history of sudden death |
| 🔹 ↑ QT interval | |
| 🔹 Syncope with triggers → Exercise, startle and sleeping |
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Syncope that occurs while supine or sitting, at rest, and without warning symptoms suggests an arrhythmic etiology
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Warmth and sweating directs attention to what syncopal etiology
History/physical is key.
Initial Test of choice
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Continuous ECG monitoring can evaluate for transient arrhythmia (ventricular tachycardia) that may not be detected on initial ECG.
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