Department of Epidemiology, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100037, China; Key Laboratory of Cardiovascular Epidemiology, Chinese Academy of Medical Sciences, Beijing 100037, China.
Function Test Center, Fuwai Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100037, China.
Sci Total Environ. 2023 Mar 10;863:160983. doi: 10.1016/j.scitotenv.2022.160983. Epub 2022 Dec 16.
Several studies reported temperature exposure was associated with altered cardiac automatic function, while this effect of temperature on hourly heart rate variability (HRV) among populations with cardiovascular risks was seldom addressed.
We conducted this panel study in four Chinese cities with three repeated visits among 296 participants at intermediate to high-risk of cardiovascular disease (CVD). Real-time temperature level and 24-h ambulatory electrocardiogram were monitored during each seasonal visit. Linear mixed-effects models were used to investigate associations between individual temperature and HRV parameters, and the seasonal effects and circadian effect were also evaluated.
We found the overall downward trend of hourly HRV associated with acute exposure to higher temperature. For each 1 °C increment in temperature of 1-3 h prior to HRV measurements (lag 1-3 h), hourly standard deviation of normal-to-normal intervals (SDNN) decreased by 0.38% (95% confidence interval [CI]: 0.22, 0.54), 0.28% (95% CI: 0.12, 0.44), and 0.20% (95% CI: 0.04, 0.36), respectively. Similar inverse associations between temperature and HRV were observed in stratified analyses by temperature level. Inverse associations for cold and warm seasons were also observed, despite some effects gradually decreased and reversed in the warm season as lag times extended. Moreover, HRV showed a more significant reduction with increased temperature during daytime than nighttime. Percent change of hourly SDNN was -0.41% (95% CI: -0.62, -0.21) with 1 °C increment of lag 1 h during daytime, while few obvious changes were revealed during nighttime.
Generally, increasing temperature was significantly associated with reduced HRV. Inverse relationships for cold and warm seasons were also observed. Associations during daytime were much more prominent than nighttime. Our findings clarified the relationship of temperature with HRV and provided evidence for prevention approaches to alleviate cardiac automatic dysfunction among populations at intermediate to high-risk of CVD.
几项研究报告称，温度暴露与心脏自主功能改变有关，而对于心血管风险人群中温度对每小时心率变异性（HRV）的影响，研究甚少。
我们在中国四个城市进行了这项面板研究，共有 296 名处于心血管疾病（CVD）中高危的参与者进行了三次重复访问。在每次季节性访问期间，实时监测温度水平和 24 小时动态心电图。使用线性混合效应模型来研究个体温度与 HRV 参数之间的关系，并评估季节性和昼夜节律效应。
我们发现，与急性暴露于较高温度相关的每小时 HRV 呈整体下降趋势。对于 HRV 测量前 1-3 小时（滞后 1-3 小时）的每 1°C 温度升高，正常-正常间隔标准差（SDNN）每小时分别降低 0.38%（95%置信区间：0.22，0.54）、0.28%（95%置信区间：0.12，0.44）和 0.20%（95%置信区间：0.04，0.36）。在按温度水平分层的分析中，也观察到了温度与 HRV 之间类似的反向关联。尽管随着滞后时间的延长，在温暖季节中一些影响逐渐减弱并逆转，但在寒冷和温暖季节中也观察到了相反的关联。此外，与夜间相比，随着温度的升高，HRV 的降幅更为显著。在白天，随着滞后 1 小时的温度升高 1°C，每小时 SDNN 的百分比变化为-0.41%（95%置信区间：-0.62，-0.21），而夜间几乎没有明显变化。
一般来说，温度升高与 HRV 降低显著相关。对于寒冷和温暖季节也观察到了相反的关系。白天的关联比夜间更为显著。我们的研究结果阐明了温度与 HRV 的关系，并为缓解中高危 CVD 人群心脏自主功能障碍提供了预防措施的证据。
