Graham C, Sastre A, Cook M R, Kavet R, Gerkovich M M, Riffle D W
Midwest Research Institute, Kansas City, MO 64110, USA.
Bioelectromagnetics. 2000 Sep;21(6):413-21.
Clinical and epidemiological studies attest that alterations in heart rate variability (HRV) are predictive of specific types of cardiovascular morbidity and mortality in otherwise healthy persons. Recent reports also suggest that changes in HRV may be associated with exposure to intermittent magnetic fields (60 Hz, 28.3 microT) in the laboratory and that mortality is increased in cardiac disease categories related to altered HRV for utility workers whose jobs involve longer exposure to elevated magnetic fields. This study combined three approaches to learn more about the specific exposure circumstances under which changes in HRV occur. First, cardiac autonomic control, as indexed by HRV spectral analysis measures, was measured in 24 men during exposure to a much higher intensity field than any previously examined (resultant flux density = 127.3 microT [1273 milliGauss, mG]). Second, HRV measures from the same individual were compared across three relevant test conditions: intermittent and continuous field exposure and during a no-exposure, control condition. Third, electrocardiographic data were analyzed to determine if the precise timing of when the magnetic field switched on or off in relation to the cardiac cycle results in phase-resetting of the human cardiac rhythm. HRV measures were not altered by either field exposure condition compared to the control condition, and no evidence for a phase-resetting mechanism was found. Further research is needed to resolve the differences between the present and the earlier laboratory-based studies of HRV and to determine if cardiac rhythm disturbances are associated with exposure to the more complex magnetic fields found in the man-made environment.
临床和流行病学研究证明，心率变异性（HRV）的改变可预测健康人群中特定类型的心血管疾病发病率和死亡率。最近的报告还表明，HRV的变化可能与实验室中间歇性磁场（60Hz，28.3微特斯拉）的暴露有关，并且对于工作中较长时间暴露于高强度磁场的公用事业工人，与HRV改变相关的心脏病类别中的死亡率会增加。本研究结合了三种方法，以更多地了解HRV发生变化的具体暴露情况。首先，在24名男性暴露于比以往任何研究都高得多的强度场（合成通量密度=127.3微特斯拉[1273毫高斯，mG]）期间，通过HRV频谱分析测量指标来测量心脏自主控制。其次，在三种相关测试条件下比较同一个体的HRV测量值：间歇性和连续性场暴露以及无暴露的对照条件。第三，分析心电图数据，以确定磁场相对于心动周期开启或关闭的精确时间是否会导致人体心律的相位重置。与对照条件相比，两种场暴露条件均未改变HRV测量值，并且未发现相位重置机制的证据。需要进一步的研究来解决目前与早期基于实验室的HRV研究之间的差异，并确定心律紊乱是否与暴露于人造环境中发现的更复杂磁场有关。
