Pathophysiological study on the effects of shift work on cardiovascular diseases

本研究的目的是阐明轮班工作对心血管疾病的病理生理影响。研究人群包括156名男性轮班工人和90名男性日工谁曾受雇于一家铜冶炼厂。测量ECG上心率调整的QT间期（QTc）、100个RR间期的总功率谱密度（t-PSD）、频率为0.04-0.15 Hz和0.15-0.4 Hz的PSD（PSD_<LF>和PSD_<HF>）、RR间期变异性（CV_<RR>）、LF和HF分量变异性（C-CV_<LF>和C-CV_<HF>）和%LF（PSD_<LF>/（PSD_<LF>+PSD_<HF>）100）（认为LF和HF分量分别反映交感神经和副交感神经活动）。轮班工人与白班工人在年龄、吸烟习惯、生化指标和血压方面无显著性差异。轮班工作者的QTc较白班工作者明显延长。倒班工人的C-CV_<LF>和对数转换PSD<LF>_显著降低。在白班工作者中，QTc与对数转换的t-PSD、PSD_<HF>、C-CV_<HF>和%LF显著相关。这些结果表明，健康男性QTc间期延长反映了心脏自主神经功能的抑制，特别是副交感神经功能减退。轮班工人的QTc延长似乎与心脏自主神经功能减退有关，部分原因是交感神经功能减退。为了预防轮班工人的心血管死亡，最大限度地减少进一步的职业压力，可以减少副交感神经活动，除了轮班工作，可能是重要的。

The purpose of this study was to clarify the pathophysiological effects of shift work on cardiovascular diseases. The study population consisted of 156 male shift workers and 90 male day workers who had been employed at a copper-smelter plant. The heart rate-adjusted QT interval (QTc) on ECG, total power spectral density (t-PSD) of 100 RR intervals, PSDs with frequencies of 0.04-0.15 Hz and of 0.15-0.4 Hz (PSD_<LF> and PSD_<HF>), RR interval variability (CV_<RR>), LF- and HF-component variability (C-CV_<LF> and C-CV_<HF>) and %LF(PSD_<LF>/(PSD_<LF>+PSD_<HF>) 100) were measured (LF and HF components are thought to reflect the sympathetic and parasympathetic activities, respectively). There were no significant differences in age, smoking habit, biochemical data or blood pressure between the shift and day workers. The QTc in the shift workers was significantly prolonged as compared to the day workers. By contrast, the C-CV_<LF> and log-transformed PSD_<LF> were significantly depressed in the shift workers. In the day workers, the QTc was significantly correlated with the log-transformed t-PSD and PSD_<HF>, C-CV_<HF> and %LF. These findings suggest that QTc prolongation in healthy men reflects depression of the cardiac autonomic function, especially parasympathetic hypoactivity. The prolonged QTc in shift workers appears to be associated with the cardiac autonomic hypofunction, partly due to sympathetic hypoactivity. For the prevention of cardiovascular mortality in shift workers, minimizing further occupational stress that can reduce the parasympathetic activity, except shift work, may be important.