Cargando…

Mechanisms of tilt‐induced vasovagal syncope in healthy volunteers and postural tachycardia syndrome patients without past history of syncope

Upright tilt table testing has been used to test for vasovagal syncope (VVS) but can result in “false positives” in which tilt‐induced fainting (tilt+) occurs in the absence of real‐world fainting. Tilt+ occurs in healthy volunteers and in patients with postural tachycardia syndrome (POTS) and show...

Descripción completa

Detalles Bibliográficos
Autores principales: Stewart, Julian M., Shaban, Mohamed A., Fialkoff, Tyler, Tuma‐Marcella, Brianna, Visintainer, Paul, Terilli, Courtney, Medow, Marvin S.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: John Wiley and Sons Inc. 2019
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6597794/
https://www.ncbi.nlm.nih.gov/pubmed/31250563
http://dx.doi.org/10.14814/phy2.14148
_version_ 1783430652408889344
author Stewart, Julian M.
Shaban, Mohamed A.
Fialkoff, Tyler
Tuma‐Marcella, Brianna
Visintainer, Paul
Terilli, Courtney
Medow, Marvin S.
author_facet Stewart, Julian M.
Shaban, Mohamed A.
Fialkoff, Tyler
Tuma‐Marcella, Brianna
Visintainer, Paul
Terilli, Courtney
Medow, Marvin S.
author_sort Stewart, Julian M.
collection PubMed
description Upright tilt table testing has been used to test for vasovagal syncope (VVS) but can result in “false positives” in which tilt‐induced fainting (tilt+) occurs in the absence of real‐world fainting. Tilt+ occurs in healthy volunteers and in patients with postural tachycardia syndrome (POTS) and show enhanced susceptibility to orthostatic hypotension. We hypothesized that the mechanisms for hypotensive susceptibility differs between tilt+ healthy volunteers (Control‐Faint (N = 12)), tilt+ POTS patients (POTS‐Faint (N = 12)) and a non‐fainter control group of (Control‐noFaint) (N = 10). Subjects were studied supine and during 70° upright tilt while blood pressure (BP), cardiac output (CO), and systemic vascular resistance (SVR), were measured continuously. Impedance plethysmography estimated regional blood volumes, flows, and vascular resistance. Heart rate was increased while central blood volume was decreased in both Faint groups. CO increased in Control‐Faint because of reduced splanchnic vascular resistance; splanchnic pooling was similar to Control‐noFaint. Splanchnic blood flow in POTS‐Faint decreased and resistance increased similar to Control‐noFaint but splanchnic blood volume was markedly increased. Decreased SVR and splanchnic arterial vasoconstriction is the mechanism for faint in Control‐Faint. Decreased CO caused by enhanced splanchnic pooling is the mechanism for faint in POTS‐Faint. We propose that intrahepatic resistance is increased in POTS‐Faint resulting in pooling and that both intrahepatic resistance and splanchnic arterial vasoconstriction are reduced in Control‐Faint resulting in increased splanchnic blood flow and reduced splanchnic resistance.
format Online
Article
Text
id pubmed-6597794
institution National Center for Biotechnology Information
language English
publishDate 2019
publisher John Wiley and Sons Inc.
record_format MEDLINE/PubMed
spelling pubmed-65977942019-07-11 Mechanisms of tilt‐induced vasovagal syncope in healthy volunteers and postural tachycardia syndrome patients without past history of syncope Stewart, Julian M. Shaban, Mohamed A. Fialkoff, Tyler Tuma‐Marcella, Brianna Visintainer, Paul Terilli, Courtney Medow, Marvin S. Physiol Rep Original Research Upright tilt table testing has been used to test for vasovagal syncope (VVS) but can result in “false positives” in which tilt‐induced fainting (tilt+) occurs in the absence of real‐world fainting. Tilt+ occurs in healthy volunteers and in patients with postural tachycardia syndrome (POTS) and show enhanced susceptibility to orthostatic hypotension. We hypothesized that the mechanisms for hypotensive susceptibility differs between tilt+ healthy volunteers (Control‐Faint (N = 12)), tilt+ POTS patients (POTS‐Faint (N = 12)) and a non‐fainter control group of (Control‐noFaint) (N = 10). Subjects were studied supine and during 70° upright tilt while blood pressure (BP), cardiac output (CO), and systemic vascular resistance (SVR), were measured continuously. Impedance plethysmography estimated regional blood volumes, flows, and vascular resistance. Heart rate was increased while central blood volume was decreased in both Faint groups. CO increased in Control‐Faint because of reduced splanchnic vascular resistance; splanchnic pooling was similar to Control‐noFaint. Splanchnic blood flow in POTS‐Faint decreased and resistance increased similar to Control‐noFaint but splanchnic blood volume was markedly increased. Decreased SVR and splanchnic arterial vasoconstriction is the mechanism for faint in Control‐Faint. Decreased CO caused by enhanced splanchnic pooling is the mechanism for faint in POTS‐Faint. We propose that intrahepatic resistance is increased in POTS‐Faint resulting in pooling and that both intrahepatic resistance and splanchnic arterial vasoconstriction are reduced in Control‐Faint resulting in increased splanchnic blood flow and reduced splanchnic resistance. John Wiley and Sons Inc. 2019-06-27 /pmc/articles/PMC6597794/ /pubmed/31250563 http://dx.doi.org/10.14814/phy2.14148 Text en © 2019 The Authors. Physiological Reports published by Wiley Periodicals, Inc. on behalf of The Physiological Society and the American Physiological Society This is an open access article under the terms of the http://creativecommons.org/licenses/by/4.0/ License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
spellingShingle Original Research
Stewart, Julian M.
Shaban, Mohamed A.
Fialkoff, Tyler
Tuma‐Marcella, Brianna
Visintainer, Paul
Terilli, Courtney
Medow, Marvin S.
Mechanisms of tilt‐induced vasovagal syncope in healthy volunteers and postural tachycardia syndrome patients without past history of syncope
title Mechanisms of tilt‐induced vasovagal syncope in healthy volunteers and postural tachycardia syndrome patients without past history of syncope
title_full Mechanisms of tilt‐induced vasovagal syncope in healthy volunteers and postural tachycardia syndrome patients without past history of syncope
title_fullStr Mechanisms of tilt‐induced vasovagal syncope in healthy volunteers and postural tachycardia syndrome patients without past history of syncope
title_full_unstemmed Mechanisms of tilt‐induced vasovagal syncope in healthy volunteers and postural tachycardia syndrome patients without past history of syncope
title_short Mechanisms of tilt‐induced vasovagal syncope in healthy volunteers and postural tachycardia syndrome patients without past history of syncope
title_sort mechanisms of tilt‐induced vasovagal syncope in healthy volunteers and postural tachycardia syndrome patients without past history of syncope
topic Original Research
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6597794/
https://www.ncbi.nlm.nih.gov/pubmed/31250563
http://dx.doi.org/10.14814/phy2.14148
work_keys_str_mv AT stewartjulianm mechanismsoftiltinducedvasovagalsyncopeinhealthyvolunteersandposturaltachycardiasyndromepatientswithoutpasthistoryofsyncope
AT shabanmohameda mechanismsoftiltinducedvasovagalsyncopeinhealthyvolunteersandposturaltachycardiasyndromepatientswithoutpasthistoryofsyncope
AT fialkofftyler mechanismsoftiltinducedvasovagalsyncopeinhealthyvolunteersandposturaltachycardiasyndromepatientswithoutpasthistoryofsyncope
AT tumamarcellabrianna mechanismsoftiltinducedvasovagalsyncopeinhealthyvolunteersandposturaltachycardiasyndromepatientswithoutpasthistoryofsyncope
AT visintainerpaul mechanismsoftiltinducedvasovagalsyncopeinhealthyvolunteersandposturaltachycardiasyndromepatientswithoutpasthistoryofsyncope
AT terillicourtney mechanismsoftiltinducedvasovagalsyncopeinhealthyvolunteersandposturaltachycardiasyndromepatientswithoutpasthistoryofsyncope
AT medowmarvins mechanismsoftiltinducedvasovagalsyncopeinhealthyvolunteersandposturaltachycardiasyndromepatientswithoutpasthistoryofsyncope