Clinical Autonomic Research

, Volume 14, Issue 1, pp 30–33

Carotid baroreflex function ceases during vasovagal syncope

  • Shigehiko Ogoh
  • Stefanos Volianitis
  • Peter B. Raven
  • Niels H. Secher
SHORT COMMUNICATION

Abstract.

Despite the arterial baroreflex control of heart rate and blood pressure, vasovagal syncope is a common cause of loss of consciousness in people exposed to stimuli that reduce the central blood volume, such as head-up tilt. Carotid baroreflex function was evaluated using a rapid pulse train of neck pressure and neck suction in three conscious volunteers who developed a vasovagal episode during head-up tilt. The maximal gain of the carotid-heart rate and carotid-blood pressure baroreflex function curves were identified as measures of carotid baroreceptor responsiveness. When presyncopal symptoms developed, one further baroreflex assessment was obtained before the subjects were returned to the supine position. The bradycardia and hypotension exhibited during pre-syncope and syncope reflected a leftward and downward relocation of both the cardiac and vasomotor stimulusresponse curves. In addition, during the vasovagal syncope, baroreflex control was suppressed as blood pressure remained low during neck pressure stimuli. In conclusion, arterial baroreflex function ceases during vasovagal syncope.

Key words

Bezold-Jarisch reflex blood pressure bradycardia head-up tilt hypotension 

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Copyright information

© Steinkopff Verlag 2004

Authors and Affiliations

  • Shigehiko Ogoh
    • 1
  • Stefanos Volianitis
    • 2
  • Peter B. Raven
    • 1
  • Niels H. Secher
    • 2
  1. 1.Dept. of Integrative PhysiologyUniversity of North Texas, Health Science CentreFort WorthUSA
  2. 2.The Copenhagen Muscle Research Centre, Dept. of AnaesthesiaUniversity of Copenhagen, Rigshospitalet 2041Copenhagen ØDenmark

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