title: Comparison of heart rate variability and cardiac arrhythmias in polluted and clean air episodes in healthy individuals.
abstract: OBJECTIVE
  Pathophysiological mechanisms and pathways linking cardiovascular mortality and morbidity with air pollution were recently hypothesized. The present study evaluated association between air pollution and changes in heart rate variability as a marker of cardiac autonomic function in healthy individuals, and also determined the frequency of cardiac arrhythmias and QT interval changes on polluted compared to unpolluted days.
  
  
  METHODS
  Continuous Holter electrocardiography (ECG) monitoring was conducted on 21 young healthy individuals in the two episodes of clean air and elevated air pollution in Tehran. All subjects underwent a medical history review, a physical examination and echocardiography in order to rule out structural heart diseases. Measured pollutants and parameters included NO(2), CO(2), O(3), SO(2), and PM10, which all showed significantly higher concentrations on polluted days. Holter parameters were measured for 24-h time segments and compared.
  
  
  RESULTS
  Maximum heart rate was significantly lower in polluted air conditions in comparison with clean air conditions (115.1 ± 32.2 vs. 128.9 ± 17.7), and the square root of the mean of squared differences between adjacent NN intervals (r-MSSD) was higher in polluted air compared to clean air (99.0 ± 58.2 vs. 58.5 ± 26.4). Also, the occurrence of nonsustained supraventricular tachycardia was reported in 42.9% of participants in air pollution episodes, whereas this arrhythmia was not seen in clear air conditions (p = 0.001).
  
  
  CONCLUSIONS
  Changes in air pollution indices may lead to the occurrence of nonsustained supraventricular tachycardia, a slight reduction in maximum heart rate, and an increase in r-MSSD in healthy individuals. Air quality monitoring in cities associated with a high exposure to air pollutants is recommended in order to prevent such events.
authors: Tehran Heart Center, Tehran University of Medical Sciences, North Kargar Street, Tehran, 1411713138, Iran. ghdavoodi@yahoo.com
authors: Gholamreza
authors: G
authors: Davoodi
authors: Ahmad Yamini
authors: AY
authors: Sharif
authors: Ali
authors: A
authors: Kazemisaeid
authors: Saeed
authors: S
authors: Sadeghian
authors: Ali Vasheghani
authors: AV
authors: Farahani
authors: Mehrdad
authors: M
authors: Sheikhvatan
authors: Mina
authors: M
authors: Pashang