title: Paroxysmal atrioventricular block induced during head-up tilt testing in an apparently healthy man.
abstract: BACKGROUND
  Prolonged asystole during head-up tilt testing has been reported, but the occurrence of paroxysmal AV block appears to be rare.
  
  
  RESULTS
  A 25-year-old man with no history of syncope underwent head-up tilt testing. After 11 minutes of 80 degrees tilting, he developed syncope with paroxysmal AV block and asystole lasting 10.5 seconds. However, this response was not reproduced during a subsequent tilt test 4 weeks later. Treadmill exercise testing and Holter monitoring showed no abnormalities. Power spectral analysis of heart rate variability revealed a marked increase in sympathetic activity several minutes before the induction of paroxysmal AV block.
  
  
  CONCLUSIONS
  We report a case of paroxysmal AV block that occurred during head-up tilt testing but did not recur on a subsequent test in an apparently healthy young man.
authors.affiliation: Department of Cardiology, Juntendo University Izunagaoka Hospital, Shizuoka, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Sumiyoshi
authors.forename: Y
authors.initials: Y
authors.lastname: Nakata
authors.forename: Y
authors.initials: Y
authors.lastname: Mineda
mesh_terms: D000328:Adult; D001794:Blood Pressure / Q000502:physiology; D018660:Blood Pressure Monitoring, Ambulatory; D005080:Exercise Test; D006327:Heart Block / Q000503:physiopathology*; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D008297:Male; D011187:Posture / Q000502:physiology*; D013575:Syncope / Q000503:physiopathology; D018667:Tilt-Table Test