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Syncope1DefinitionSyncope is a transient lost of conciousness due to transient global cerebral hypoperfusion characterized by rapid onset, short duration, and spontaneous complete recovery.The adjective pre-syncopal is used to indicate symptoms and signs that occur before unconsciousness in syncope, making it asynonym of warning and prodromal.2CausesVascular (62%)Reflex (neurally-mediated) syncopeVaso-vagal (mediated by emotional and orthostatic stress)Situational (cough, sneeze, GI stimulation, post-micturition, post-exercise, post-prandial)Carotic sinus syncope

3Causes (cont.)Orthostatic hypotensionPrimary autonomic failureSecondary autonomic failure (diabetes, spinal cord injury, uremia)Drug-induced orthostatic hypotension (alcohol, vasodilator, diuretic, antidepressant)Volume depletion (hemorrhage, diarrhea, vomiting)

4Causes (cont.)Cardiac syncope (10%)ArrhythmiaBradycadia (AV conduction system malfunction, nodal dysfunction)Tachycardia (supraventricular, ventricular)Drug induced bradycardia and tachycardia Inherited syndrome: Long QT syndrome, Brugada syndromeStructuralValvular disease, Acute MI, HOCM, atrial myxoma, cardiac tamponade, prosthetic valve dysfunction.Others: pulmonary embolism, aortic dissection, pulmonary hypertension.

5Causes (cont.)Neurological (5%)Migraine or TIA(vertebrobasilar origin)Toxic or metabolic (2%)Anti-arrhythmic causing pro-arrhythmic effectAnti-hypertensive causing orthostatic hypotensionHypoglycemiaPsychiatric (1.5%)Idiopathic (14%)

6Pathophysiology

Transient insufficiency of global cerebral nutrient flow.Transient reduction of blood oxygen.Transient decrease in arterial BP.7In healthy young people, cerebral blood flow represents 12% to 15% of resting cardiac output.A sudden cessation of cerebral blood flow for only 6 to 10 seconds is sufficient to cause complete loss of consciousness.Syncope occurs due to global cerebral hypoperfusion. Brain parenchyma depends on adequate blood flow to provide a constant supply of glucose, the primary metabolic substrate. Brain tissue cannot store energy in the form of high-energy phosphates found elsewhere in the body.8Cerebral perfusion is maintained relatively constant by an intricate and complex feedback system involving cardiac output, systemic vascular resistance, arterial pressure, intravascular volume status, cerebrovascular resistance with intrinsic autoregulation, and metabolic regulation. A clinically significant defect in any one of these or subclinical defects in several of these systems may cause syncope.

9Emergencies in syncopeMyocardial infarctionCardiac arrhytmiasAortic dissectionCardiac tamponadeHypoglycemiaAddisons diseaseMassive pulmonary embolism102007 American College of Emergency Physicians (ACEP) Clinical Policy on Syncope lists history and physical examination and 12-lead ECG as their only current level A recommendations.11HistoryPrecipitating factor (e.g sleep or food deprivation, warm ambient environment, alcohol consumption, pain, and strong emotions such as fear or apprehension.)Activity prior to syncope (at rest, change of posture, on exertion, coughing, voiding or prolonged standing) ***Syncope happens within 2 minutes of standing suggest orthostatic hypotensionStanding? Sitting? Lying?

12Hx (cont.)Was lost of consciousness complete?Was LOC with rapid onset and short duration?Was recovery spontaneous, complete and without sequelae?Was postural tone lost?

13Hx (cont.)Symptoms (pre-syncope)DizzinessLight-headednessVertigoWeaknessDiaphoresisEpigastric discomfortNauseaBlurred visionPallorParesthesias

14Hx (cont.)Syncope vs seizure?LOC in syncope about seconds to 1 minutesSeizure- post-event confusion, oral trauma, incontinence, myalgiasWitnessesConvulsive activity, automatisms- seizure15Hx (cont.)Medical Hx (drugs that reduce blood pressure, affect CO, prolong QT interval, altered sensory system, alter serum electrolytes)Family Hx (MI, arrhytmias, valvular heart disease, cardiomyopathies, CHF)Other differentials of syncope (Hx of seizures, diabetes, stroke, pregnancy)16Physical examinationVital signsCVS and Respiratory system examination (arrhythmias, valvular heart disease, signs of CCF, carotids stenosis)CNS examinationSigns of TraumaHallpike maneuver (video)Tilt Table test (video)Carotid sinus massage

17InvestigationSerum glucose levelFBCRenal ProfileCardiac enzymeChest X-rayElectrocardiogramEchocardiogramHolter monitoringStress test18Carotid sinus massage has been used with some success to diagnose carotid sinus syncope.Patients are placed on a cardiac monitor and beat-to-beat BP monitoring device. Atropine is kept at the bedside.Longitudinal massage lasting 5 seconds is initiated at the point of greatest carotid pulse intensity at the level of the thyroid cartilage on one side at a time.The maximal response occurs after approximately 18 seconds, and a positive result is one that produces 3 seconds of asystole or syncope. If the result is negative, the process is repeated on the other carotid sinus.Carotid sinus massage may theoretically precipitate an embolic stroke in persons with preexisting carotid artery disease.

19San Francisco Syncope RuleThe San Francisco syncope rule was developed to identify patients at risk of a serious outcome within 30 days of presentation and needing admission to hospital.

Five criteria (CHESS) used to calculate the San Francisco syncope rule are:Congestive heart failure historyHaematocrit