title: Short-term heart rate variability response to head-up tilt in young syncope patients and controls with respect to age.
abstract: This study aims at characterizing the short-term time-courses of time- and frequency-domain heart rate variability (HRV) parameters during head-up tilt test (HUTT). Data from 44 young patients with a history of syncope and 34 age-matched controls was analysed in two age-groups related to puberty (< or =13 and > or =14 years), and separately for gender, by extracting minute-by-minute progression of mean RR-interval, standard deviation of RR-intervals (SDNN) and their first difference (SDSD) as well as low-frequency (LF, 0.05-0.15 Hz) energy, high-frequency (HF, 0.15-0.4 Hz) energy and the LF/HF-ratio. Time-courses were individually normalized and averaged after synchronization to the events of tilt and tilt-back/syncope. We observed remarkable age-related differences not only with respect to response to tilting but also regarding the differentiation of patients with positive HUTT from controls with negative HUTT. ROC-analysis in three regions of interest (0-2 min after tilt, 2-5 min after tilt, 5-2 min before tilt-back) revealed generally much weaker and less persistent differences in younger subjects whereas in elders the differences were clearer and often most pronounced immediately before syncope. For both age-groups, the relative change of mean RR provided best separation, however in elders in the ROI just before syncope (sensitivity: 74%, specificity 80%) in young immediately after tilt (sens.: 71%, spec.: 74%). In elder subjects, the relative reduction of SDNN 2-5 minute after tilt achieved almost the same performance (sens.: 74%, spec. 80%) as in the ROI before syncope (sens. 78%, spec. 73%), indicating the existence of rather early precursors of syncope that might help to predict the outcome of the HUTT in subjects in or after puberty.
authors.affiliation: Dept. of Med. Informatics, Heidelberg Univ., Germany. hartmut.dickhaus@med.uni-heidelberg.de
authors.forename: Hartmut
authors.initials: H
authors.lastname: Dickhaus
authors.forename: Christoph
authors.initials: C
authors.lastname: Maier
authors.forename: Markus
authors.initials: M
authors.lastname: Khalil
authors.forename: Herbert
authors.initials: H
authors.lastname: Ulmer
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D019540:Area Under Curve; D002648:Child; D005260:Female; D006339:Heart Rate; D006801:Humans; D008297:Male; D012372:ROC Curve; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012815:Signal Processing, Computer-Assisted; D013575:Syncope / Q000175:diagnosis* / Q000473:pathology*; D018667:Tilt-Table Test / Q000295:instrumentation*