Syncope classification
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]: Associate Editor(s)-in-Chief: Sahar Memar Montazerin, M.D.[2] Sara Zand, M.D.[3]
Overview
Syncope is defined as abrupt, transient complete loss of consciousness, inability to keep postural tone, rapid spontaneous recovery with the mechanism of cerebral hypoperfusion. Syncope is usually classified based on the underlying mechanisms leading to hypoperfusion. Syncope is classified to reflex-mediated, orthostatic hypotension, and cardiovascular subtypes. Neurally-mediated syncope (common faint) is the most common type of reflex syncope in younger patients occurs during upright position (standing, sitting) with prodrome symptoms including diaphoresis, warmth, nausea, and pallor, usually after emotional stress, pain, medical setting. Orthostasis hypotension is explained as reduction in systolic blood pressure of ≥20 mmHg or diastolic blood pressure of ≥10 mm Hg within 3 minutes of standing position and is common in older patients. Carotid sinus syndrome which is a type of reflex syncope due to carotid sinus hypersensitivity is defined as pause ≥3 seconds and/or a reduction of systolic blood pressure ≥50 mm Hg during stimulation of the carotid sinus and is more common in older patients. There are some conditions that are incorrectly diagnosed as syncope. These conditions are usually associated with partial or complete loss of consciousness such as epilepsy, metabolic disorders, transient ischemic attack or conditions with loss of posture and without loss of consciousness like cataplexy, drop attacks, falls and pseudo-syncope.
Classification
Syncope is usually classified based on the underlying mechanisms leading to cerebral hypoperfusion. According to 2017AHA/ACC/HRS guideline, syncope is classified to:[1]
| Classification of syncope | Definition |
|---|---|
| Syncope | Abrupt, transient complete loss of consciousness, inability to keep postural tone, rapid spontaneous recovery with the mechanism of cerebral hypoperfusion |
| Pre syncope, near syncope | The symptoms before syncope including lightheadedness, visual sensations, such as tunnel vision or graying out, variable degrees of altered consciousness without complete loss of consciousness |
| Unexplained syncope | Undetermined etiology after initial evaluation including history, physical examination, ECG |
| Orthostatic intolerance | Frequent, recurrent, or persistent lightheadedness, palpitations, tremulous, generalized weakness, blurred vision, exercise intolerance, fatigue upon standing. These symptoms happen with or without orthostasis tachycardia, orthostasis intolerance or syncope. Patients have more than one symptoms with inability to maintain standing posture. |
| Orthostatic tachycardia | Increasing heart rate ≥30 bpm within 10 minutes after standing (without exercise) from recumbent position oror ≥40 bpm in individuals 12–19 year of age |
| Orthostatic hypotension | Decreasing systolic blood pressure of ≥20 mmHg or diastolic blood pressure of ≥10 mm Hg in standing position |
| Initial (immediate) orthostatic hypotension | A transient reduction in blood pressure within 15 seconds after standing accompanied by syncope or presyncope |
| Classic orthostatic hypotension | A sustain reduction in systolic blood pressure of ≥20 mmHg or diastolic blood pressure of ≥10 mm Hg within 3 minutes of standing position |
| Delayed orthostatic hypotension | A sustain reduction in systolic blood pressure of ≥20 mmHg (or 30 mm Hg in patients with supine hypertension) or diastolic blood pressure of ≥10 mm Hg after 3 minutes of standing position |
| Neurogenic hypotension | A subtype of orthostasis hypotension due to central or peripheral autonomic nervous system dysfunction |
| Cardiac syncope | tachyarrhythmia, bradyarhythmia, hypotension due to Low cardiac output state, valvular , bloodflow obstruction, vascular dissection, vasodilation leading syncope |
| Non cardiac syncope | reflex syncope, orthostatic hypotension, volume depletion, dehydration, blood loss |
| Reflex (neurally mediated) syncope | Syncope due to vasodilation, bradycardia or both |
| Vasovagal syncope | The most common type of reflex syncope mediated by vasovagal reflex during upright position( standing , sitting) presented with prodrome symptoms including diaphoresis, warmth, nausea, and pallor after emotional stress, pain, medical setting. Taking history and [[physical examination] and eyewitness may helpful for the diagnosis. |
| Carotid sinus syndrome | A type of reflex syncope due to carotid sinus hypersensitivity defined as pause ≥3 seconds and/or a reduction of systolic blood pressure ≥50 mm Hg during stimulation of the carotid sinus, more common in older patients |
| Situational syncope | A type of reflex syncope after specific physical functions such as coughing, laughing, swallowing, micturition, defecation |
| Postural orthostatic tachycardia syndrome (POTS) | an increase in heart rate of ≥30 bpm during a positional change from supine to standing (or ≥40 bpm in those 12–19 year of age) in the absence of orthostatic hypotension (>20 mm Hg reduction in systolic blood pressure). [[Heart rate> 120/ min in standing position and symptoms such as lightheadedness, palpitations, tremulousness, generalized weakness, blurred vision, exercise intolerance, and fatigue in standing position which are not related to specific functions ( bloating, nausea, diarrhea, abdominal pain. |
| Psychogenic pseudosyncope | False unconsciousness in the absent of cardiac, reflex, neurologic, metabolic causes |
There are some conditions that are incorrectly diagnosed as syncope. These conditions are usually associated with partial or complete loss of consciousness or with loss of posture and without loss of consciousness. The table below is one of the suggested classification systems for syncope:[2][3][4]
| Neurally-Mediated Syncope |
| Vasovagal |
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| Situational |
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| Carotid sinus syncope |
| Syncope due to Orthostatic Hypotension |
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| Autonomic failure |
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| Drug induced: |
| Volume depletion |
| Cardiovascular Syncope |
| Arrhythmia |
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| Structural heart disease |
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| Other cardiovascular: |
| Conditions Incorrectly Diagnosed as Syncope |
| Disorders with partial or complete loss of consciousness |
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| Conditions without loss of consciousness |
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| The above table adopted from ESC guideline |
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References
- ↑ Shen, Win-Kuang; Sheldon, Robert S.; Benditt, David G.; Cohen, Mitchell I.; Forman, Daniel E.; Goldberger, Zachary D.; Grubb, Blair P.; Hamdan, Mohamed H.; Krahn, Andrew D.; Link, Mark S.; Olshansky, Brian; Raj, Satish R.; Sandhu, Roopinder Kaur; Sorajja, Dan; Sun, Benjamin C.; Yancy, Clyde W. (2017). "2017 ACC/AHA/HRS Guideline for the Evaluation and Management of Patients With Syncope: A Report of the American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines and the Heart Rhythm Society". Circulation. 136 (5). doi:10.1161/CIR.0000000000000499. ISSN 0009-7322.
- ↑ Moya, A.; Sutton, R.; Ammirati, F.; Blanc, J.-J.; Brignole, M.; Dahm, J. B.; Deharo, J.-C.; Gajek, J.; Gjesdal, K.; Krahn, A.; Massin, M.; Pepi, M.; Pezawas, T.; Granell, R. R.; Sarasin, F.; Ungar, A.; van Dijk, J. G.; Walma, E. P.; Wieling, W.; Abe, H.; Benditt, D. G.; Decker, W. W.; Grubb, B. P.; Kaufmann, H.; Morillo, C.; Olshansky, B.; Parry, S. W.; Sheldon, R.; Shen, W. K.; Vahanian, A.; Auricchio, A.; Bax, J.; Ceconi, C.; Dean, V.; Filippatos, G.; Funck-Brentano, C.; Hobbs, R.; Kearney, P.; McDonagh, T.; McGregor, K.; Popescu, B. A.; Reiner, Z.; Sechtem, U.; Sirnes, P. A.; Tendera, M.; Vardas, P.; Widimsky, P.; Auricchio, A.; Acarturk, E.; Andreotti, F.; Asteggiano, R.; Bauersfeld, U.; Bellou, A.; Benetos, A.; Brandt, J.; Chung, M. K.; Cortelli, P.; Da Costa, A.; Extramiana, F.; Ferro, J.; Gorenek, B.; Hedman, A.; Hirsch, R.; Kaliska, G.; Kenny, R. A.; Kjeldsen, K. P.; Lampert, R.; Molgard, H.; Paju, R.; Puodziukynas, A.; Raviele, A.; Roman, P.; Scherer, M.; Schondorf, R.; Sicari, R.; Vanbrabant, P.; Wolpert, C.; Zamorano, J. L. (2009). "Guidelines for the diagnosis and management of syncope (version 2009): The Task Force for the Diagnosis and Management of Syncope of the European Society of Cardiology (ESC)". European Heart Journal. 30 (21): 2631–2671. doi:10.1093/eurheartj/ehp298. ISSN 0195-668X.
- ↑ Sutton, Richard (2013). "Clinical Classification of Syncope". Progress in Cardiovascular Diseases. 55 (4): 339–344. doi:10.1016/j.pcad.2012.11.005. ISSN 0033-0620.
- ↑ Puppala, Venkata Krishna; Dickinson, Oana; Benditt, David G. (2014). "Syncope: Classification and risk stratification". Journal of Cardiology. 63 (3): 171–177. doi:10.1016/j.jjcc.2013.03.019. ISSN 0914-5087.