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Influence of 50 Hz magnetic field on human heart rate variablilty: Linear and nonlinear analysis
Author(s) -
Tabor Zbisław,
Michalski Józef,
Rokita Eugeniusz
Publication year - 2004
Publication title -
bioelectromagnetics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.435
H-Index - 81
eISSN - 1521-186X
pISSN - 0197-8462
DOI - 10.1002/bem.20039
Subject(s) - detrended fluctuation analysis , heart rate variability , approximate entropy , heart rate , medicine , standard deviation , analysis of variance , mathematics , cardiology , beat (acoustics) , statistics , physics , time series , scaling , blood pressure , acoustics , geometry
This study investigated the problem of the influence of 50 Hz magnetic field (MF) on human heart rate variability (HRV). The exposure system was a commercial device for magnetotherapy, generating field of the strength of 500 μT at the center of the coil, 150–200 μT at the position of human subjects' heart and 20–30 μT at the position of subjects' head. The exposure protocols, applied randomly, were either “half hour MF‐off/half hour MF‐on” or “half hour MF‐off/half hour MF‐off.” The phonocardiographic (PhCG) signal of 15 volunteers were obtained during exposure and used for calculation of time‐domain HRV parameters (mean time between heart beats (N‐N), standard deviation of time between heart beats (SDNN), and the number of differences of successive beat‐to‐beat intervals greater than 50 ms, divided by the total number of beat‐to‐beat intervals (pNN50)) and nonlinear HRV measures (approximate entropy (ApEn), detrended fluctuation scaling exponents). The protocol MF‐off/MF‐on was applied in nine subjects. Repeated measures ANOVA (RMANOVA) performed for Mf‐off/MF‐off protocol indicated no statistical difference among four 15 min intervals of HRV data ( P value >20% for all parameters except for N‐N, where P = 3.7%). RMANOVA followed by the post hoc Tukey test performed for Mf‐off/MF‐on protocol indicated a statistically significant difference during MF on for N‐N (8% increase, P < .1%), SDNN (40% increase, P = 1.1%), and pNN50 (110% increase, P < .1%). The results of the analysis indicate that the changes of these parameters could be associated with the influence of MF. Bioelectromagnetics 25:474–480, 2004. © 2004 Wiley‐Liss, Inc.