367 Ch 366. Syncope

Syncope = transient LOC due to global cerebral hypoperfusion + spontaneous complete recovery；distinguish from seizure (LOC + abnormal motor), psychogenic non-epileptic spells, drop attacks (no LOC)；three major categories: (1) Reflex (neurally mediated) — vasovagal (most common), situational, carotid sinus; (2) Orthostatic — drug-induced, volume depletion, autonomic failure; (3) Cardiac (most concerning) — arrhythmia (brady/tachy), structural (AS, HCM, PE, MI)；workup: history (typical features) + orthostatic vitals + ECG (all syncope) + structural disease evaluation (echo if suspected); tilt table, carotid sinus massage, loop recorder as needed；risk stratification (SF Syncope Rule, OESIL, EGSYS)：admit if high-risk (cardiac suspected, abnormal ECG, structural disease, severe injury, ↑ trop); discharge low-risk vasovagal with reassurance + counseling。