Analysis of QT Interval during Passive Tilt Test: Comparison of Different Correction Formula
نویسندگان
چکیده
We analyzed the QT and RR interval time series continuously recorded during 90 degrees passive Tilt test in 10 young healthy subjects (age 2625 years, 5 females). Changes in QT interval were assessed on 1 minute time related templates and on rate-independent waveforms obtained by averaging beats preceded by the same RR interval. Following Tilt, the mean RR interval shortened from 927273 ms to 7332118 ms, p<O.OI); Bazett corrected QT increased (QTb : from 403912 ms to 4132221 ms, p=0.058) whereas exponential QTe did not change signijhntly. Conversely, QTf and QTI (respectively Fridericia and linear rate-corrected QT), decreased after Tilt (e.g. QTfi 39821 I ms vs 391214 ms, p<O.O5). Comparison at identical heart rate confirmed a QT shortening (QTrr: 387214 ms vs 363315 ms, p<O.OI). Thus, rate-correction formula are inconsistent and should be used with caution when assessing autonomic nervous system changes.
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