Variability of near-fainting responses in healthy 6-16-year-old subjects.
1. Fainting is a common phenomenon in young subjects, but the final events before the actual faint are not well known. The aim of the present study was to study the inter-individual variability of haemodynamic events associated with near-fainting in children and teenagers. 2. Sixty-eight healthy subjects (aged 6-16 years) performed a 70 degrees tilt-up test with intravascular instrumentation for 5 min. Responses in 29 near-fainting subjects were analysed and compared with 39 non-fainting subjects. Arterial pressure was measured by Finapres. Left ventricular stroke volume was computed from the pressure pulsation waveform. 3. Inability to maintain vasomotor tone was the mechanism underlying near-fainting in the vast majority of near-fainting subjects. The three classical haemodynamic responses (vasovagal, vasodepressor and vagal) could be recognized, but large individual differences were found. After tilt back, blood pressure in near-fainters showed a mirror response to the stage before tilt-back; blood pressure gradually increased and was normal at 1 min after tilt-back. 4. The variability in haemodynamic responses on approach of an orthostatic faint is wide in the young.
de Jong-de Vos van Steenwijk
C C
CC
University Hospital for Children and Youth, het Wilhelmina Kinderziekenhuis, Utrecht, The Netherlands.
Wieling
W
W
Harms
M P
MP
Wesseling
K H
KH
D000293:Adolescent; D001794:Blood Pressure / Q000502:physiology; D018660:Blood Pressure Monitoring, Ambulatory; D002302:Cardiac Output / Q000502:physiology; D002648:Child; D004562:Electrocardiography; D005260:Female; D006339:Heart Rate / Q000502:physiology; D006439:Hemodynamics / Q000502:physiology*; D006801:Humans; D007024:Hypotension, Orthostatic / Q000503:physiopathology*; D008297:Male; D012815:Signal Processing, Computer-Assisted; D013318:Stroke Volume / Q000502:physiology; D013575:Syncope / Q000503:physiopathology*; D018667:Tilt-Table Test; D013997:Time Factors; D014655:Vascular Resistance / Q000502:physiology