The origin of vasovagal syncope: to protect the heart or to escape predation?
Abstract
Major lines of evidence suggest that classical (emotional and orthostatic) vasovagal syncope (VVS) is not a disease, but rather a manifestation of a non-pathological trait. It is, therefore, reasonable to investigate the possible factors that may explain its origin and evolution. We reviewed the data available in the literature on the vasovagal reaction in humans and animals in order to identify possible similarities that might provide insight into the evolution of VVS. We found two processes which appear relevant to the investigation of VVS evolution: fear and threat bradycardia in animals, and the vasovagal reflex during hemorrhagic shock in humans and animals. We suggest that VVS in humans involves physiological mechanisms similar to those found in other vertebrates, and that this may indicate a common evolutionary root. The available data seem to suggest that VVS evolved as an advantageous response to inescapable predators or to stressful and possibly dangerous heart conditions. The inhibition of the sympathetic system, together with activation of the vagal system, characterizes VVS. The consequent slowing of the heart rate induced by VVS may constitute a beneficial break of the cardiac pump, thereby reducing myocardial oxygen consumption. We suggest that classical VVS did not evolve recently in the modern human lineage; rather, it should be regarded as a selected response, which probably evolved in the ancient past as a "defense mechanism" of the organism within some ancestral group(s) of vertebrates.
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VVS is highly probable if syncope is precipitated by pain, fear, or standing, and is associated with typical progressive prodrome (pallor, sweating, and/or nausea).
“VVS is highly probable if syncope is precipitated by pain, fear, or standing, and is associated with typical progressive prodrome (pallor, sweating, and/or nausea). 8,13-17”
From 2018 ESC Guidelines for the diagnosis and management of syncope (2018) · cites this paper as [15]
Situational reflex syncope is highly probable if syncope occurs during or immediately after specific triggers, listed in Table 3.
“Situational reflex syncope is highly probable if syncope occurs during or immediately after specific triggers, listed in Table 3 . 8, 13-17”
From 2018 ESC Guidelines for the diagnosis and management of syncope (2018) · cites this paper as [15]
Cites
Looking at pictures: Affective, facial, visceral, and behavioral reactions
LANG, P. J., GREENWALD, M. K., BRADLEY, M. M., & HAMM, A. O. (1993) · Psychophysiology · doi:10.1111/j.1469-8986.1993.tb03352.x · Cited by 3,190 · see citing works
Guidelines on management (diagnosis and treatment) of syncope
Brignole, M. (2001) · European Heart Journal · doi:10.1053/euhj.2001.2739 · Cited by 951 · see citing works
Guidelines on Management (diagnosis and treatment) of syncope ? update 2004
Brignole, M., Alboni, P., Benditt, D. G., Bergfeldt, L., Blanc, J., Thomsen, P. E. B., van Dijk, J. G., Fitzpatrick, A. P., Hohnloser, S. H., Janousek, J., et al. (2004) · EP Europace · doi:10.1016/j.eupc.2004.08.008 · Cited by 648 · see citing works
Self-citationDiagnostic value of history in patients with syncope with or without heart disease
Alboni, P., Brignole, M., Menozzi, C., Raviele, A., Del Rosso, A., Dinelli, M., Solano, A., & Bottoni, N. (2001) · Journal of the American College of Cardiology · doi:10.1016/s0735-1097(01)01241-4 · Cited by 444 · see citing works
Self-citationHemodynamic and neurohumoral responses to acute hypovolemia in conscious mammals
Schadt, J. C., & Ludbrook, J. (1991) · American Journal of Physiology-Heart and Circulatory Physiology · doi:10.1152/ajpheart.1991.260.2.h305 · Cited by 424 · see citing works
Animal hypnosis: Factual status of a fictional concept.
Gallup, G. G. (1974) · Psychological Bulletin · doi:10.1037/h0037227 · Cited by 370 · see citing works
Prevalence and triggers of syncope in medical students
Ganzeboom, K. S., Colman, N., Reitsma, J. B., Shen, W. K., & Wieling, W. (2003) · The American Journal of Cardiology · doi:10.1016/s0002-9149(03)00127-9 · Cited by 366 · see citing works
Sympathetic outflow to muscles during vasovagal syncope
Wallin, B. G., & Sundlöf, G. (1982) · Journal of the Autonomic Nervous System · doi:10.1016/0165-1838(82)90001-7 · Cited by 326 · see citing works
LIESHOUT, J. J. V., Wieling, W., Karemaker, J. M., & Eckberg, D. L. (1991) · Clinical Science · doi:10.1042/cs0810575 · Cited by 322 · see citing works
Romanes, G. J., & Darwin, C. R. (2011) · Cambridge University Press eBooks · doi:10.1017/cbo9781139103664 · Cited by 300 · see citing works
Epidemiology of reflex syncope
Colman, N., Nahm, K., Ganzeboom, K. S., Shen, W.-K., Reitsma, J. B., Linzer, M., Wieling, W., & Kaufmann, H. (2004) · Clinical Autonomic Research · doi:10.1007/s10286-004-1003-3 · Cited by 278 · see citing works
McIntosh, S. J., Lawson, J., & Kenny, R. A. (1993) · The American Journal of Medicine · doi:10.1016/0002-9343(93)90261-m · Cited by 238 · see citing works
Evaluation of Syncope by Upright Tilt Testing with Isoproterenol
Kapoor, W. N., & Brant, N. (1992) · Annals of Internal Medicine · doi:10.7326/0003-4819-116-5-358 · Cited by 237 · see citing works
Death Feigning by Ducks in Response to Predation by Red Foxes (Vulpes fulva)
Sargeant, A. B., & Eberhardt, L. E. (1975) · The American Midland Naturalist · doi:10.2307/2424542 · Cited by 227 · see citing works
Dorward, P. K., Riedel, W., Burke, S. L., Gipps, J., & Korner, P. I. (1985) · Circulation Research · doi:10.1161/01.res.57.4.618 · Cited by 198 · see citing works
Natale, A., Akhtar, M., Jazayeri, M., Dhala, A., Blanck, Z., Deshpande, S., Krebs, A., & Sra, J. S. (1995) · Circulation · doi:10.1161/01.cir.92.1.54 · Cited by 192 · see citing works
Abboud, F. M. (1989) · New England Journal of Medicine · doi:10.1056/nejm198902093200609 · Cited by 176 · see citing works
Neurophysiologic studies of the immobility reflex (animal hypnosis).
Klemm, W. R. (1971) · Neurosciences Research · doi:10.1016/b978-0-12-512504-8.50011-1 · Cited by 154 · see citing works
Victor, R. G., Thorén, P., Morgan, D. A., & Mark, A. L. (1989) · Circulation Research · doi:10.1161/01.res.64.4.686 · Cited by 147 · see citing works
Is the normalisation of blood pressure in bleeding trauma patients harmful?
Roberts, I., Evans, P. A., Bunn, F., Kwan, I., & Crowhurst, E. (2001) · The Lancet · doi:10.1016/s0140-6736(00)03653-9 · Cited by 144 · see citing works
Brignole, M., Menozzi, C., Gianfranchi, L., Oddone, D., LOLLI, G., & BERTULLA, A. (1991) · American Heart Journal · doi:10.1016/0002-8703(91)90282-m · Cited by 138 · see citing works
Age of First Faint in Patients with Vasovagal Syncope
SHELDON, R. S., SHELDON, A. G., CONNOLLY, S. J., MORILLO, C. A., KLINGENHEBEN, T., KRAHN, A. D., KOSHMAN, M., RITCHIE, D., & for the Investigators of the Syncope Symptom Study and the Prevention of Syncope Trial (2006) · Journal of Cardiovascular Electrophysiology · doi:10.1111/j.1540-8167.2005.00267.x · Cited by 134 · see citing works
Meck, J. V., Waters, W. W., Ziegler, M. G., DeBlock, H. F., Mills, P. J., Robertson, D., & Huang, P. L. (2004) · American Journal of Physiology-Heart and Circulatory Physiology · doi:10.1152/ajpheart.00740.2003 · Cited by 129 · see citing works
ÖBerg, B., & White, S. (1970) · Acta Physiologica Scandinavica · doi:10.1111/j.1748-1716.1970.tb04803.x · Cited by 125 · see citing works
Catecholamines in vasovagal fainting
Chosy, J. J., & Graham, D. T. (1965) · Journal of Psychosomatic Research · doi:10.1016/0022-3999(65)90032-2 · Cited by 117 · see citing works
Neurally Mediated Syncopal Syndromes: Pathophysiological Concepts and Clinical Evaluation
Benditt, D. G. (1997) · Pacing and Clinical Electrophysiology · doi:10.1111/j.1540-8159.1997.tb06211.x · Cited by 116 · see citing works
Circulatory control mechanisms in vasodepressor syncope
Goldstein, D. S., Spanarkel, M., Pitterman, A. B., Toltzis, R. J., Gratz, E., Epstein, S. E., & Keiser, H. R. (1982) · American Heart Journal · doi:10.1016/0002-8703(82)90442-2 · Cited by 112 · see citing works
Sander-Jensen, K., Secher, N. H., Bie, P., Warberg, J., & Schwartz, T. W. (1986) · BMJ · doi:10.1136/bmj.292.6517.364 · Cited by 107 · see citing works
Cardiac and Respiratory Function During Sudden Prolonged Immobility in Wild Rodents
Hofer, M. A. (1970) · Psychosomatic Medicine · doi:10.1097/00006842-197011000-00008 · Cited by 107 · see citing works
The acoustic startle reflex and its modulation: effects of age and gender in humans
Ludewig, K., Ludewig, S., Seitz, A., Obrist, M., Geyer, M. A., & Vollenweider, F. X. (2003) · Biological Psychology · doi:10.1016/s0301-0511(03)00074-7 · Cited by 103 · see citing works
Redistribution of Cardiac Output during Hemorrhage in the Unanesthetized Monkey
Forsyth, R. P., HOFFBRAND, B. I., & Melmon, K. L. (1970) · Circulation Research · doi:10.1161/01.res.27.3.311 · Cited by 102 · see citing works
Diving bradycardia and withdrawal bradycardia in Caiman crocodilus.
GAUNT, A. S., & GANS, C. (1969) · Nature · doi:10.1038/223207a0 · Cited by 92 · see citing works
Predisposition to Vasovagal Syncope in Subjects With Blood/Injury Phobia
Accurso, V., Winnicki, M., Shamsuzzaman, A., Wenzel, A. E., Johnson, A. K., & Somers, V. K. (2001) · Circulation · doi:10.1161/hc3301.094910 · Cited by 90 · see citing works
Williams, R. B., Bittker, T. E., Buchsbaum, M. S., & Wynne, L. C. (1975) · Psychophysiology · doi:10.1111/j.1469-8986.1975.tb00017.x · Cited by 87 · see citing works
Powell, D. A., & Kazis, E. (1976) · Psychophysiology · doi:10.1111/j.1469-8986.1976.tb00858.x · Cited by 87 · see citing works
Decrease in cardiac output and muscle sympathetic activity during vasovagal syncope
Jardine, D. L., Melton, I. C., Crozier, I. G., English, S., Bennett, S. I., Frampton, C. M., & Ikram, H. (2002) · American Journal of Physiology-Heart and Circulatory Physiology · doi:10.1152/ajpheart.00640.2001 · Cited by 86 · see citing works
Physiological responses associated with feigned death in the American opossum
Gabrielsen, G. W., & SMITH, E. N. (1985) · Acta Physiologica Scandinavica · doi:10.1111/j.1748-1716.1985.tb07605.x · Cited by 85 · see citing works
Morita, H., Nishida, Y., Motochigawa, H., Uemura, N., Hosomi, H., & Vatner, S. (1988) · Circulation Research · doi:10.1161/01.res.63.1.165 · Cited by 83 · see citing works
Is vasovagal syncope a disease?
Alboni, P., Brignole, M., & Uberti, E. C. D. (2007) · EP Europace · doi:10.1093/europace/eul179 · Cited by 81 · see citing works
Self-citationWainwright, S. A. (1992) · Journal of Biomechanics · doi:10.1016/0021-9290(92)90085-f · Cited by 77 · see citing works
Alarm Bradycardia in White-Tailed Deer Fawns (Odocoileus virginianus)
Jacobsen, N. K. (1979) · Journal of Mammalogy · doi:10.2307/1379806 · Cited by 74 · see citing works
Burke, S. L., & Dorward, P. K. (1988) · The Journal of Physiology · doi:10.1113/jphysiol.1988.sp017191 · Cited by 72 · see citing works
Serotonergic mechanisms mediate renal sympathoinhibition during severe hemorrhage in rats
Morgan, D. A., Thorén, P., Wilczynski, E. A., Victor, R. G., & Mark, A. L. (1988) · American Journal of Physiology-Heart and Circulatory Physiology · doi:10.1152/ajpheart.1988.255.3.h496 · Cited by 72 · see citing works
Biochemical Changes in Two Subjects Succumbing to Syncope
Vlngerhoets, A. J. J. M. (1984) · Psychosomatic Medicine · doi:10.1097/00006842-198403000-00002 · Cited by 69 · see citing works
“Emotional” Bradycardia: A Telemetry Study on Incubating Willow Grouse (Lagopus lagopus)
Gabrielsen, G. W., KANWISHER, J. W., & Steen, J. B. (1977) · Acta Physiologica Scandinavica · doi:10.1111/j.1748-1716.1977.tb05944.x · Cited by 68 · see citing works
ON THE MECHANISM OF TONIC IMMOBILITY IN VERTEBRATES
Hoagland, H. (1928) · The Journal of General Physiology · doi:10.1085/jgp.11.6.715 · Cited by 64 · see citing works
The Mechanisms behind the Rapid Blood Volume Restoration after Hemorrhage in Birds
Djojosugito, A. M., Folkow, B., & Kovách, A. G. B. (1968) · Acta Physiologica Scandinavica · doi:10.1111/j.1748-1716.1968.tb04220.x · Cited by 63 · see citing works
Endogenous opiate peptides may limit norepinephrine release during hemorrhage.
Schadt, J. C., & Gaddis, R. R. (1985) · Journal of Pharmacology and Experimental Therapeutics · doi:10.1016/s0022-3565(25)20912-0 · Cited by 62 · see citing works
Rayner, J. M. V., & Wootton, R. J. (1991) · Bristol Research (University of Bristol) · Cited by 61 · see citing works
Vasovagal syncope and Darwinian fitness
Diehl, R. R. (2005) · Clinical Autonomic Research · doi:10.1007/s10286-005-0244-0 · Cited by 56 · see citing works
The Mechanism of Tonic Immobility (“Animal Hypnosis”)
Hoagland, H. (1928) · The Journal of General Psychology · doi:10.1080/00221309.1928.9918019 · Cited by 56 · see citing works
Sánchez-Navarro, J. P., Martínez-Selva, J. M., & Román, F. (2006) · International Journal of Psychophysiology · doi:10.1016/j.ijpsycho.2005.10.023 · Cited by 48 · see citing works
van Dijk, J. G. (2003) · Clinical Autonomic Research · doi:10.1007/s10286-003-0099-1 · Cited by 47 · see citing works
Profound Sympathoinhibition Complicating Hypovolemia in Humans
Sanders, J. S., & Ferguson, D. W. (1989) · Annals of Internal Medicine · doi:10.7326/0003-4819-111-5-439 · Cited by 46 · see citing works
Bracha, H. S., Bracha, A. S., Williams, A. E., Ralston, T. C., & Matsukawa, J. M. (2005) · Clinical Autonomic Research · doi:10.1007/s10286-005-0245-z · Cited by 43 · see citing works
Why does vasodilatation occur during syncope?
ROBINSON, B. J., & Johnson, R. H. (1988) · Clinical Science · doi:10.1042/cs0740347 · Cited by 42 · see citing works
Cardiovascular Changes during Preparation for Fighting Behaviour in the Cat
Adams, D. B., Baccelli, G., Mancia, G., et al. (1968) · Nature · doi:10.1038/2201239a0 · Cited by 40 · see citing works
SIMULATION OF ACUTE HAEMORRHAGE IN UNANAESTHETIZED RABBITS
Ludbrook, J., Potocnik, S. J., & Woods, R. L. (1988) · Clinical and Experimental Pharmacology and Physiology · doi:10.1111/j.1440-1681.1988.tb01116.x · Cited by 40 · see citing works
LIBERSON, W. T., SMITH, R. W., & STERN, A. (1991) · Journal of Neuropsychiatry · doi:10.1176/jnp.3.1.28 · Cited by 40 · see citing works
Haemodynamic Responses to Haemorrhage in the Snake, Elaphe Obsoleta Obsoleta
Lillywhite, H. B., & Smith, L. H. (1981) · Journal of Experimental Biology · doi:10.1242/jeb.94.1.275 · Cited by 39 · see citing works
Cardiac responses in alarmed red deer calves
Espmark, Y. O., & Langvatn, R. (1979) · Behavioural Processes · doi:10.1016/0376-6357(79)90032-9 · Cited by 34 · see citing works
Regulation of arterial blood pressure in the common green iguana
Hohnke, L. (1975) · American Journal of Physiology-Legacy Content · doi:10.1152/ajplegacy.1975.228.2.386 · Cited by 34 · see citing works
Kenney, R. A., & Neil, E. (1951) · The Journal of Physiology · doi:10.1113/jphysiol.1951.sp004524 · Cited by 30 · see citing works
Effects of haemorrhage on the distribution of the peripheral blood flow in the rabbit
Chalmers, J. P., Korner, P. I., & White, S. W. (1967) · The Journal of Physiology · doi:10.1113/jphysiol.1967.sp008317 · Cited by 28 · see citing works
Zimmer, H., Vossel, G., & Fröhlich, W. D. (1990) · International Journal of Psychophysiology · doi:10.1016/0167-8760(90)90016-7 · Cited by 27 · see citing works
Tonic immobility in the squirrel monkey (Saimiri sciureus)
Hennig, C. W. (1978) · Primates · doi:10.1007/bf02382801 · Cited by 27 · see citing works
Casonato, A., Pontara, E., Bertomoro, A., et al. (2003) · PubMed · Cited by 25 · see citing works
Role of the serotonergic system in the genesis of vasovagal syncope
Alboni, P. (2000) · EP Europace · doi:10.1053/eupc.1999.0088 · Cited by 24 · see citing works
Self-citationDevelopment of fear-related heart rate responses in neonatal rabbits
Sebastiani, L., Salamone, D., Silvestri, P., Simoni, A., & Ghelarducci, B. (1994) · Journal of the Autonomic Nervous System · doi:10.1016/0165-1838(94)90013-2 · Cited by 15 · see citing works
Possible Relationships between Orienting and Diving Reflexes
GOODMAN, D. A., & Weinberger, N. M. (1970) · Nature · doi:10.1038/2251153b0 · Cited by 15 · see citing works
Waxman, M. B., Asta, J. A., & CAMERON, D. A. (1992) · Canadian Journal of Physiology and Pharmacology · doi:10.1139/y92-118 · Cited by 15 · see citing works
FARADAY, F. J. (1884) · Nature · doi:10.1038/029335c0 · Cited by 14 · see citing works
Vasovagal fainting as an evolutionary remnant of the fight against hemorrhage
Levi, M. M. (2005) · Clinical Autonomic Research · doi:10.1007/s10286-005-0252-0 · Cited by 13 · see citing works
Survival of pigeon after graded haemorrhage.
Kovách, A. G., & Szász, E. (1968) · PubMed · Cited by 13 · see citing works
Mechanism of hypotensive transients associated with abrupt bradycardias in conscious rabbits
Sheldon, R. S., Wright, C. I., Duff, H. J., Thakore, E., Gillis, A. M., & Roach, D. E. (2007) · Canadian Journal of Cardiology · doi:10.1016/s0828-282x(07)70817-6 · Cited by 11 · see citing works
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Developed in collaboration with, European Heart Rhythm Association (EHRA), Heart Failure Association (HFA), and Heart Rhythm Society (HRS), societies, E. B. T. F., European Society of Emergency Medicine (EuSEM), European Federation of Internal Medicine (EFIM), European Union Geriatric Medicine Society (EUGMS), American Geriatrics Society (AGS), European Neurological Society (ENS), et al. (2009) · European Heart Journal · doi:10.1093/eurheartj/ehp298 · Cited by 2,040 · see citing works
2018 ESC Guidelines for the diagnosis and management of syncope
Brignole, M., Moya, A., de Lange, F. J., Deharo, J.-C., Elliott, P. M., Fanciulli, A., Fedorowski, A., Furlan, R., Kenny, R. A., Martín, A., et al. (2018) · European Heart Journal · doi:10.1093/eurheartj/ehy037 · Cited by 1,951 · see citing works
The effects of trauma on brain and body: A unifying role for the midbrain periaqueductal gray
Terpou, B. A., Harricharan, S., McKinnon, M. C., Frewen, P., Jetly, R., & Lanius, R. A. (2019) · Journal of Neuroscience Research · doi:10.1002/jnr.24447 · Cited by 82 · see citing works
The psychophysiology of blood-injection-injury phobia: Looking beyond the diphasic response paradigm
Ritz, T., Meuret, A. E., & Ayala, E. S. (2010) · International Journal of Psychophysiology · doi:10.1016/j.ijpsycho.2010.05.007 · Cited by 74 · see citing works
“This second phase makes BII phobia a unique phenomenon among the anxiety disorders and has provoked a plethora of functional interpretations and speculations about its adaptivity (e.g., Alboni et al., 2008; Bracha et al. 2007; Marks, 1988).”
BackgroundIs there any point to vasovagal syncope?
van Dijk, J. G., & Sheldon, R. (2008) · Clinical Autonomic Research · doi:10.1007/s10286-008-0484-x · Cited by 47 · see citing works
Circulating endocannabinoid concentrations during orthostatic stress
Schroeder, C., Batkai, S., Engeli, S., Tank, J., Diedrich, A., Luft, F. C., & Jordan, J. (2009) · Clinical Autonomic Research · doi:10.1007/s10286-009-0026-1 · Cited by 26 · see citing works
Ritz, T., Meuret, A. E., & Simon, E. (2013) · Behaviour Research and Therapy · doi:10.1016/j.brat.2013.03.011 · Cited by 15 · see citing works
Timing of syncope during blood sampling – the Maastricht Study
Martens, R. J. H., Geijselaers, S. L. C., Stehouwer, C. D. A., & Henry, R. M. A. (2017) · European Journal of Internal Medicine · doi:10.1016/j.ejim.2017.05.024 · Cited by 5 · see citing works
- Authors
- Alboni, P., Alboni, M., & Bertorelle, G.
- Affiliations
- University of Sassari (IT)
- University of Ferrara (IT)
- ORCID
- Bertorelle, Giorgio
- Venue
- Clinical Autonomic Research
- Published
- 2008-06-30
- Volume
- 18
- Issue
- 4
- Pages
- 170-8
- ISSN
- 0959-9851 (ISSN-L)
- 1619-1560
- OpenAlex
- W2032169947
- Cited by
- 93
- References
- 75
- Citations by year
- 2025: 3 · 2024: 3 · 2023: 1 · 2022: 3 · 2021: 7 · 2020: 4 · 2019: 2 · 2018: 9 · 2017: 6 · 2016: 4 · 2015: 6 · 2014: 8 · 2013: 7 · 2012: 7
- FWCI
- 1.25
- Type
- journal article
- Language
- en
- Open access
- closed
- Locations
- Clinical Autonomic Research (publishedVersion)
- PubMed (publishedVersion)
- Institutional Research Information System University of Ferrara (University of Ferrara) (submittedVersion)
- Topics
- Health Sciences › Medicine › Surgery › Cardiovascular Syncope and Autonomic Disorders
- Health Sciences › Medicine › Cardiology and Cardiovascular Medicine › Heart Rate Variability and Autonomic Control
- Life Sciences › Neuroscience › Neurology › Vagus Nerve Stimulation Research
- Keywords
- vasovagal syncope, evolutionary origin, hemorrhagic shock, vasovagal reflex, sympathoinhibition, vagal activation, predator escape, myocardial oxygen consumption, cardiac pump, vertebrate evolution, orthostatic syncope
- MeSH terms
- Animals, Blood Pressure, Bradycardia, Biological Evolution, Fear, Heart Rate, Humans, Reflex, Shock, Hemorrhagic, Syncope, Vasovagal
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