Predisposition to vasovagal syncope in subjects with blood/injury phobia

Valentina Accurso, Mikolaj Winnicki, Abu S.M. Shamsuzzaman, Amy Wenzel, Alan Kim Johnson, Virend K. Somers

Research output: Contribution to journalArticlepeer-review

72 Scopus citations


Background - Most subjects with blood/injury phobia experience syncope or presyncope as part of the phobic response. We tested the hypothesis that these subjects have a constitutional autonomic dysregulation that predisposes them to vasovagal syncope during head-up tilt. Methods and Results - We studied 11 subjects (9 females, 2 males) who had a history of syncope or presyncope only in response to a blood or injury stimulus and 11 healthy matched controls (10 females, 1 male) without a history of syncope. Blood pressure (BP) and heart rate (HR) were measured during a 15-minute baseline period with subjects in the supine position and then during 45 minutes of head-up tilt to 70°. Measurements at rest did not differ between the blood phobic and control subjects. During tilt, 9 (82%) of the 11 blood phobic subjects experienced presyncope or syncope, leading to termination of the study after 22±17 minutes of tilt. Only 1 (9%) of the 11 control subjects experienced presyncope (X2=11.7, P=0.001). Hemodynamic responses to tilt were consistent with a vasovagal mechanism in the blood phobic subjects, with simultaneous decreases in BP and HR during tilt. During tilt, systolic BP fell by 21±15 mm Hg (P=0.001), and HR fell by 22±25 bpm (P=0.01). By contrast, BP and HR were very stable in the control group. Conclusions - Subjects with syncope related to blood/injury phobia have an underlying autonomic dysregulation predisposing them to neurally mediated syncope, even in the absence of any blood or injury stimulus. Fainting related to these stimuli may in large part be due to dysfunction in neural circulatory control, which may secondarily lead to the phobia because of repeated syncopal events.

Original languageEnglish (US)
Pages (from-to)903-907
Number of pages5
Issue number8
StatePublished - Aug 21 2001


  • Autonomic
  • Blood pressure
  • Heart rate
  • Nervous system
  • Syncope

ASJC Scopus subject areas

  • Cardiology and Cardiovascular Medicine
  • Physiology (medical)


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