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Approach to SyncopeSyncope [1]Transient LOC from cerebral hypoxia with spontaneous revivalUsually from decreased cerebral blood flow (also anemia, hypoxemia)Epidemiology: 1/3 of individuals in the general population; bimodal (20s; 80s); 1% of ED visits; 1/3 admittedFour main categories of etiologyCardiogenic – decreased CO HypovolemiaDysrhythmia Heart failure (pulsus alternans, cold extremities)PEValvular lesions (MC: AS)HOCM (avoid vasodilators, diuretics, inotropes) Aortic dissection (differential arm BPs; RFs- prior cardiac surgery, male, 60-70s, HTN, bicuspid AV, Marfan’s)pHTN Cardiac tamponade (elevated JVP, low CO, muffled heart sounds; pulsus paradoxus – Korotkoff sounds 1st heard in expiration, then both) Subclavian steal syndrome (retrograde blood flow in vertebral artery from narrowing of the ipsilateral subclavian artery; upper arm exercises)MC – atherosclerosisYounger pt – consider large vessel vasculitis, thoracic outlet syndrome, postsurgical stenosisNeurocardiogenic (aka “reflex” syncope) - neurally mediated circuit bradycardia and vasodilation Vasovagal (MCC syncope in general population, 25%) Situational (coughing, swallowing, laughing, micturition, defecation) Carotid hypersensitivity (rare <40yo; rotation or turning of head; tight collars, neckwear, shaving)DysautonomiaTilt table testing – drop in BP with little change in HR (c.f. orthostatic hypoTN)POTS (postural orthostatic tachycardia syndrome)Young women; orthostatic sxs with other autonomic abnormalities (hyperhidrosis, fatigue, migraine, sleep) Tilt table testing – exaggerated increase in HRTx: BB; fludrocortisone, midodrine, SSRIsNeurogenic shock (hypoTN with bradycardia) Neurologic SzHypoglycemiaTIA/strokeVertebrobasilar insufficiency – turning head upward can cause external mechanical forces on an already compromised vertebrobasilar arteries poor perfusion to RAS OtherMeds (alpha blocker, beta blocker, diuretics, nitrates, sedating meds) Hyperventilation (hypocapnia causes cerebral vasoconstriction decrease in cerebral blood flow)Psychogenic pseudo-syncope (conversion disorder; absence of true LOC) Convulsive Syncope vs. Epilepsy [2]Abrupt cerebral hypoperfusion causes brief stiffening/nonsustained myoclonusNot at increased risk for developing epilepsy Preceded by presyncope and associated sxs (warmth, sweating, nausea)Prolonged convulsions, marked postictal confusion uncommon Misdiagnosis as epilepsy is common References: Mansoor, Andre. Frameworks for Internal Medicine, 2018.Sheldon, Robert. How to Differentiate Syncope from Seizure, Cardiol Clin 33 (2015) 377-385. ................
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