Effects of 50 Hz magnetic field exposure on human heart rate variability with passive tilting

Abstract

The question of whether power-frequency magnetic fields of strengths relevant to industrial exposure can affect heart rhythm remains controversial. Because the reported effects on heart rate (HR) are so small, procedures which can provoke changes in the sympathovagal balance in a controlled manner may have a greater capacity for identifying subtle field-related changes, if they do exist. We have investigated HR and heart rate variability (HRV) spectral indices in 20 volunteers subjected to a tilt from the supine position to 60 degrees , head up. The tilting procedure was carried out under two conditions, field (28 microT resultant, circularly polarized) and sham, in a balanced double-blind design. Subjects were instructed to breathe in time with an audible cue at 2.5 s intervals. Although the anticipated significant changes in HR and the high frequency (HF), low frequency (LF) and LF/HF ratio (log transformed) occur with tilting, there were no significant differences between corresponding measures with and without exposure to magnetic fields (tilt ln LF/HF ratio 0.94 +/- 0.19 and 0.95 +/- 0.20 for sham and field, respectively). There was also no evidence of a field-related trend in spectral alterations when the time following tilting was divided into three 256 s epochs.

The cardiovascular response to an acute 1800-μT, 60-Hz magnetic field exposure in humans

“…. Other investigators have experienced similar difficulty demonstrating a reproducible MF effect on HR and HRV (Sait et al 2006;Ghione et al 2005;Kurokawa et al 2003). The results of the present study support the findings of these researchers who have reported an absence of MF effects.…”

A literature review: the cardiovascular effects of exposure to extremely low frequency electromagnetic fields

“…These results were in agreement with their earlier results demonstrating that a 37 Hz, 80 T exposure did not result in alterations of cardiac rhythm (Ghione et al 2004). In a shift of research focus, Sait et al (2006) designed a study that provoked controlled changes in the sympathetic-parasympathetic balance in order to determine if there were any subtle Weld related changes. Using a 50 Hz, 28 T Xux density exposure chamber, they subjected 20 volunteers to a 15 min, 60° body tilt experimental session.…”

“…The paced respiration helped avoid any interference of the low frequency HRV spectrum from slow breaths while tilted. No eVect of the Weld was reported for either HR or HRV, contesting the suggestion by Sastre et al that sympathetic neural stimulation is required for Weld induced changes in ANS control (Sait et al 2006). The question of whether the paced respiration might have masked any Weld related HRV changes arises though, as it was reported that several subjects had diYculty maintaining the prescribed rate.…”

An investigation of the heart rate, heart rate variability, cardiac ions, troponin-I and CK-MB in men exposed to 1.5 T constant magnetic fields

“…HR was measured by detecting the intervals between the two QRS (electrical wave of cardiac ventricular muscle contraction). Sait et al (2006) found that HR slowed down with exposure to magnetic field. They indicated that continuous exposure to a magnetic field affected both HR and HRV and, as the strength of the field increased, the effect became significant.…”