The Effects of Seasonal Temperature Changes on Heart Rate Variability for Healthy Elder People in a Subtropical City

Abstract

The Effects of Seasonal Temperature Changes on Heart Rate Variability for Healthy Elder People in a Subtropical CityAbstract Number:1858 Li-Te Chang*, Chin-Sheng Tang, Po-Chun Huang, and Shih-Chun Candice Lung Li-Te Chang* Feng Chia University, Taiwan, E-mail Address: [email protected] Search for more papers by this author , Chin-Sheng Tang Fu-Jen Catholic University, Taiwan Search for more papers by this author , Po-Chun Huang Fu-Jen Catholic University, Taiwan Search for more papers by this author , and Shih-Chun Candice Lung Academia Sinica, Taiwan Search for more papers by this author AbstractIntroduction Environmental epidemiological studies have shown that temperature and particulate pollutants have adverse effects on cardiac autonomic function. Additionally, heart rate variability (HRV) has been an important non-invasive indicator to monitor cardiovascular health. The purpose of the study is to investigate the influences of subtropical climate extremes on HRV parameters in healthy elders using different environmental indicators.Methods We recruited seven healthy elders aged from 57-83 years residing in New Taipei City, Taiwan. For each participant, continuous measurements were made for 72 hours using mobile instruments and a portable electrocardiogram (ECG) recorder to collect the data of ECG, ambient temperature and relative humidity, and particulate pollutant exposures in both of summer and winter. Generalized additive mixed model (GAMM) was adopted to explore the association between environmental temperature/humidity indices and HRVs by controlling potential confounding factors. The environmental temperature/humidity indicators evaluated in our study included air temperature, wet bulb globe temperature (WBGT), humidex, and heat index.Results Overall, nonlinear relationships between environmental temperature/humidity indicators and HRV parameters were found. When the data were stratified by season, the WBGT indicator and most of the HRV parameters were positively associated in linear relationship during summertime, while the WBGT and most of the HRV parameters were negatively linearly correlated in winter. In multi-pollutant models, as WBGT rised 1 degree Celsius in winter, subjects’ r-MSSD, SDNN, pNN50 +1, and TP reduced by 9.8%, 5.4%, 17.3%, 9.8% in significance, respectively. In brief, analyses of the results found that the WBGT was a suitable indicator for assessing the effects of temperature/humidity changes on the HRVs of healthy elders in subtropical areas, and rising WBGT did cause significant changes of HRV parameters in different seasons.