title: [Timing of positive head-up tilt test for patients with suspected vasovagal syncope].
abstract: OBJECTIVE
  To investigate the time course of positive head-up tilt test (HUTT) for patients with suspected vasovagal syncope.
  
  
  METHODS
  Consecutive patients referred to the syncope unit of our center for recurrent unexplained syncope were included. The HUTT consisted of a 30 minute passive basic phase and a 20 minute sublingual nitroglycerin provocation phase if syncope did not develop during the passive phase.
  
  
  RESULTS
  Positive HUTT was observed in 427 out of 773 consecutive patients (55.2%) patients including 43 patients (10.1%) during the passive basic phase and 384 patients (89.9%) during the nitroglycerin provocation phase. During the basic phase, the positive Hutt developed at 7.5 minute (n = 2) and peaked at 22.5th minute (20.9%, n = 9) and then decreased gradually. Most positive reactions (93.0%, n = 40) occurred between the 10 and 25 minutes during the basic phase. During the nitroglycerin provocation phase, the percentage of positive reactions increased rapidly after sublingual nitroglycerin, peaked at the 10th minute (35.7%, n = 137) and decreased thereafter. Most positive reactions (96.1%, n = 369) occurred within the first 15 minutes of provocation phase.
  
  
  CONCLUSIONS
  The appropriate duration for HUTT test could be modified to a 25 minutes passive basic phase plus 15 minutes nitroglycerin provocation phase.
authors.affiliation: Center for Cardiac Function Test, Fu Wai Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100037, China.
authors.forename: Jun
authors.initials: J
authors.lastname: Liu
authors.forename: Yue
authors.initials: Y
authors.lastname: Liu
authors.forename: Guo-Ying
authors.initials: GY
authors.lastname: Lu
authors.forename: Zhi
authors.initials: Z
authors.lastname: Li
authors.forename: Xiao-Feng
authors.initials: XF
authors.lastname: Li
authors.forename: Yu-Shan
authors.initials: YS
authors.lastname: Wang
authors.forename: Pi-Hua
authors.initials: PH
authors.lastname: Fang
mesh_terms: D000293:Adolescent; D000328:Adult; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D019462:Syncope, Vasovagal / Q000175:diagnosis*; D018667:Tilt-Table Test; D055815:Young Adult