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| | __NOTOC__ |
| | {| class="infobox" style="float:right;" |
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| | | [[File:Siren.gif|30px|link=Syncope resident survival guide]]|| <br> || <br> |
| | | [[Syncope resident survival guide|'''Resident'''<br>'''Survival'''<br>'''Guide''']] |
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| '''For patient information click [[{{PAGENAME}} (patient information)|here]]''' | | '''For patient information click [[{{PAGENAME}} (patient information)|here]]''' |
| | {{Syncope}} |
| | {{CMG}} {{AE}} {{Sahar}} {{Sara.Zand}} |
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| {{Infobox_Disease | | | {{SK}} Vasovagal syncope; Neurally mediated syncope; Common faint; Vasodepressor syncope; Neurocardiogenic syncope |
| Name = Fainting |
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| Image = |
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| Caption = |
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| DiseasesDB = 27303 |
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| ICD10 = {{ICD10|R|55||r|50}} |
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| ICD9 = {{ICD9|780.2}} |
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| ICDO = |
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| OMIM = |
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| MedlinePlus = |
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| eMedicineSubj = |
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| eMedicineTopic = |
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| eMedicine_mult = |
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| MeshID = D013575 |
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| }}
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| {{SI}}
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| {{CMG}}
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| ==Overview== | | ==[[Syncope overview|Overview]]== |
| '''Fainting''', also called '''syncope''' ([[International Phonetic Alphabet|IPA]]: {{IPA|[ˈsɪnkəpi]}} and {{IPA|[ˈsɪŋkəpi]}}), is a sudden, and generally momentary, loss of [[consciousness]], or blacking out caused by the [[Central Ischaemic Response]], because of a lack of sufficient blood and oxygen in the brain. The first symptoms a person feels before fainting are [[dizziness]]; a dimming of vision, or [[brownout (medical)|brownout]]; [[tinnitus]]; and feeling hot. Moments later, the person's vision turns black, and he or she drops to the floor (or slumps if seated in a chair). If the person is unable to slump from the position to a near horizontal position, he or she risks dying of the [[Suspension trauma]] effect. More serious causes of fainting include cardiac ([[heart]]-related) causes such as an abnormal heart rhythm (an [[arrhythmia]]), where the heart beats too slowly, too rapidly or too irregularly to pump enough blood to the brain. Some arrhythmias can be life-threatening. Other important cardio-vascular conditions that can be manifested by syncope include [[subclavian steal syndrome]] and [[aortic stenosis]].
| | ==[[Syncope historical perspective|Historical Perspective]]== |
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| ==Common Causes== | | ==[[Syncope classification|Classification]]== |
| *Common fainting spell ([[vasovagal syncope]])
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| *[[Dehydration]] due to a wide variety of causes including diarrhea and diuretics
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| *[[Hypoglycemia]]
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| *[[Hypotension]]
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| == Complete Differential Diagnosis of Syncope== | | ==[[Syncope pathophysiology|Pathophysiology]]== |
| *[[Addison's Disease]]
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| *[[Adriamycin]]
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| *[[Alpha-blockers]]
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| *[[Alcohol]]
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| *[[Anemia]]
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| *[[Antiarrythmics]]
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| *[[Antihypertensives]]
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| *[[Anxiety]]
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| *[[Aortic Stenosis]]
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| *[[Aortic Dissection]]
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| *[[Arteriosclerosis]] of the carotid arteries
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| *[[Arteriosclerosis]] of cerebral vessels
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| *[[Arrhythmia]]
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| *[[Autonomic insufficiency]]
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| *[[Barbiturates]]
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| *[[Beta blockers]]
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| *[[Bradyarrhythmia]]
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| *[[Cardiac Tamponade]]
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| *[[Cardiomyopathy]]
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| *[[Carotid Sinus Hypersensitivity]]
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| *[[Cerebrovascular Disease]]
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| *[[Cough]]
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| *[[Cerebrovascular accident]] or [[stroke]]
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| *[[Defecation]]
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| *[[Dehydration]]
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| *[[Diarrhea]]
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| *[[Digitalis]]
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| *[[Diuretics]]
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| *[[Heart failure]]
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| *[[Hydralazine]]
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| *[[Hypoglycemia]]
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| *[[Hypoxia]]
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| *[[Hypovolemia]]
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| *[[Hyperbradykininemia]]
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| *[[Hypertensive encephalopathy]]
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| *[[Hypertrophic obstructive cardiomyopathy]]
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| *[[Hyperventilation]]
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| *[[Hysteria]]
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| *[[Methamphetamine]]
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| *[[Micturition]]
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| *[[Migrane]]
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| *[[Myocarditis]]
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| *[[Myocardial infarction]]
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| *[[Nitrates]]
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| *[[Opiates]]
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| *[[Orthostatic hypotension]]
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| *[[Pacemaker malfunction]]
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| *[[Phenothiazines]]
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| *[[Pulmonary embolism]]
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| *Reduced [[pulmonary artery]] flow
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| *[[Sedatives]]
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| *[[Seizures]]
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| *[[Sick sinus disease]]
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| *[[Situational syncope]]
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| *[[Somatization disorder]]
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| *[[Stokes-Adams attack]]
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| *[[Subclavian steal syndrome]]
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| *[[Sympathectomy]]
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| *[[Tacharrhythmia]]
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| *[[Takayasu's arteritis]]
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| *[[Transient ischemic attack]]
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| *[[Trauma]]
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| *[[Tricyclic antidepressants]]
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| *[[Vasovagal syncope]]
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| *[[Valsalva maneuver]]
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| *Valve [[thrombus]]
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| *[[Valvular disease]]
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| *[[Ventricular tachycardia]]
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| ==Types==
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| Vasovagal (situational) syncope, one of the most common types, may occur in scary or embarrassing situations or during blood drawing, coughing, or urinating. Other types include postural syncope (caused by a changing in body posture), cardiac syncope (due to heart-related conditions), and neurological syncope (due to neurological conditions). There are many other causes of syncope including low blood sugar levels and lung disease such as [[emphysema]] and a [[pulmonary embolus]]. The cause of the fainting can be determined by a doctor using a complete history, physical, and various diagnostic tests.
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| ===Vasovagal syncope===
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| {{main|Vasovagal syncope}}
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| The vasovagal type can be considered in two forms:
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| *Isolated episodes of loss of consciousness, unheralded by any warning symptoms for more than a few moments. These tend to occur in the adolescent age group, and may be associated with fasting, exercise, abdominal straining or circumstances promoting vaso-dilatation (eg heat, alcohol). The subject is invariably upright. The [[tilt-table test]], if performed, is generally negative.
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| *Recurrent syncope with complex associated symptoms. This is so-called Neurally Mediated Syncope (NMS). It is associated with any of the following: preceding or succeeding sleepiness, preceding visual disturbance ("spots before the eyes"), sweating, light-headedness. The subject is usually but not always upright. The [[tilt-table test]], if performed, is generally positive.
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| A pattern of background factors contributes to the attacks. There is typically an unsuspected relatively low blood volume, for instance, from taking a low salt diet in the absence of any salt-retaining tendency. Heat causes vaso-dilatation and worsens the effect of the relatively insufficient blood volume. That sets the scene, but the next stage is the adrenergic response. If there is underlying fear or anxiety (e.g. social circumstances), or acute fear (e.g. acute threat, needle phobia), the vaso-motor centre demands an increased pumping action by the heart (flight or fight response). This is set in motion via the adrenergic (sympathetic) outflow from the brain but the heart is unable to meet requirement because of the low blood volume, or decreased return. The high (ineffective) sympathetic activity is always modulated by vagal outflow, in these cases leading to excessive slowing of heart rate. The abnormality lies in this excessive vagal response. The tilt-table test typically evokes the attack.
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| Much of this pathway was discovered in animal experiments by Bezold (Vienna) in the 1860s. In animals, it may represent a defence mechanism when confronted by danger ("playing possum"). This reflex occurs in only some people and may be similar to that described in animals.
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| The mechanism described here suggests that a practical way to prevent attacks would be, counter-intuitively, to block the adrenergic signal with a Beta Blocker. But simpler plan is to explain the mechanism, discuss causes of fear, and optimise salt as well as water intake.
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| ===Pure cardiac syncope===
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| Fainting can also occur if pressure on the carotid artery in the neck triggers a vagal signal to the Vaso-Motor Centre, reflexly causing a vagal response to slow the heart.
| | ==[[Syncope causes|Causes]]== |
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| A pure [[cardiac arrhythmia]] is a serious matter that can appear as syncope but this is unusual. Severe narrowing of the Aortic Valve leading to syncope is included for completeness.
| | ==[[Syncope differential diagnosis|Differentiating Syncope from other Diseases]]== |
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| ===Syncope from vertebro-basilar arterial disease=== | | ==[[Syncope epidemiology and demographics|Epidemiology and Demographics]]== |
| Arterial disease in the upper spinal cord, or lower brain, causes syncope if there is a reduction in blood supply, which may occur with extending the neck or after drugs to lower blood pressure.
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| ==Clinical symptoms== | | ==[[Syncope risk factors|Risk Factors]]== |
| If the patient states, "I felt dizzy with blurry vision, muscle weakness, during the fall I bumped my knee, hit my head and passed out," then it is not syncope, it is termed pre or near-syncope.
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| If the patient states, "I felt dizzy, shadows came over my eyes, and when I woke up I was lying on the floor," then it is diagnosed as syncope.
| | ==[[Syncope natural history, complications and prognosis |Natural History, Complications and Prognosis]]== |
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| Patients who experience a syncoptic episode ''do not remember falling''.
| | ==Diagnosis== |
| | [[Syncope history and symptoms|History and Symptoms]] | [[Syncope physical examination|Physical Examination]] | [[Syncope laboratory findings|Laboratory Findings]] | [[Syncope electrocardiogram|Electrocardiogram]] | [[Syncope CT|CT]] | [[Syncope MRI|MRI]] | [[Syncope echocardiography|Echocardiography]] | [[Syncope other imaging findings|Other Imaging Findings]] | [[Syncope other diagnostic studies|Other Diagnostic Studies]] |
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| ==Treatment== | | ==Treatment== |
| Recommended treatment is to allow the person to lie on the ground with his or her legs slightly elevated. As the dizziness and the momentary blindness passes, the person may experience [[Entoptic phenomenon|visual disturbances]] in the form of small bright dots ([[phosphene]]). These will also pass within a few minutes. If fainting happens frequently, or if there is no obvious explanation, it is important to see a doctor about it.
| | [[Syncope medical therapy|Medical Therapy]] | [[Syncope surgery|Surgery]] | [[Syncope primary prevention|Primary Prevention]] | [[Syncope secondary prevention|Secondary Prevention]] | [[Syncope cost-effectiveness of therapy|Cost-Effectiveness of Therapy]] | [[Syncope future or investigational therapies|Future or Investigational Therapies]] |
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| | == Case Studies == |
| | [[Syncope case study one|Case #1]] |
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| ==See also== | | ==Related Chapters== |
| *[[Orthostatic hypotension]] blackout after rising | | *[[Orthostatic hypotension]] |
| *[[Shallow water blackout]] for the special case of fainting arising from hypocapnia | | *[[Shallow water blackout]] |
| *[[Deep water blackout]] for the special case of fainting arising from latent hypoxia | | *[[Deep water blackout]] |
| | *[[Vasovagal syncope]] |
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| == External links ==
| | {{Symptoms and signs}} |
| *[http://www.escardio.org/NR/rdonlyres/6774BAFD-71FD-4E72-9175-40F8374F9AC5/0/SyncopeupdateFVWeb4095YEUHJ101104.pdf 2004 European Society of Cardiology Guidelines on Management (Diagnosis and Treatment) of Syncope.]
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| * http://www.syncope.us
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| *[http://www.dinet.org Dysautonomia Information Network]
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| *[http://www.dynakids.org Dysautonomia Youth Network of America, Inc.]
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| *[http://www.supportdysautonomia.org Dysautonomia Support Network Corp.]
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| *[http://www.youtube.com/watch?v=-t-ZhMssEbE Tilt table test]
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| {{Symptoms and signs}}
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| [[ca:Síncope]]
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| [[de:Synkope (Medizin)]]
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| [[es:Síncope]] | | [[es:Síncope]] |
| [[fr:Syncope (médecine)]] | | [[fr:Syncope (médecine)]] |
| [[gl:Síncope]]
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| [[it:Sincope (medicina)]]
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| [[nl:Syncope (medisch)]]
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| [[ja:失神]] | | [[ja:失神]] |
| [[pl:Omdlenie]] | | [[pl:Omdlenie]] |
| [[pt:Síncope (saúde)]] | | [[pt:Síncope (saúde)]] |
| [[ru:Обморок]] | | [[ru:Обморок]] |
| [[fi:Pyörtyminen]]
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| [[sv:Svimning]]
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| [[uk:Синкопе]]
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| [[wa:Sdårniyon]]
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| [[yi:חלשות]]
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| [[zh:昏厥]] | | [[zh:昏厥]] |
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| [[Category:Emergency medicine]] | | [[Category:Emergency medicine]] |
| [[Category:Cardiology]] | | [[Category:Cardiology]] |
| [[Category:Symptoms]]
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| [[Category:Overview complete]]
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| [[Category:Neurology]] | | [[Category:Neurology]] |
| [[Category:Nutrition]] | | [[Category:Nutrition]] |
| [[Category:Metabolic disorders]] | | [[Category:Metabolic disorders]] |
