title: Effects of particle size fractions on reducing heart rate variability in cardiac and hypertensive patients.
abstract: It is still unknown whether the associations between particulate matter (PM) and heart rate variability (HRV) differ by particle sizes with aerodynamic diameters between 0.3 microm and 1.0 microm (PM(0.3-1.0)), between 1.0 microm and 2.5 microm (PM(1.0-2.5)), and between 2.5 microm and 10 microm (PM(2.5-10)). We measured electrocardiographics and PM exposures in 10 patients with coronary heart disease and 16 patients with either prehypertension or hypertension. The outcome variables were standard deviation of all normal-to-normal (NN) intervals (SDNN), the square root of the mean of the sum of the squares of differences between adjacent NN intervals (r-MSSD), low frequency (LF; 0.04-0.15 Hz), high frequency (HF; 0.15-0.40 Hz), and LF:HF ratio for HRV. The pollution variables were mass concentrations of PM(0.3-1.0), PM(1.0-2.5), and PM(2.5-10). We used linear mixed-effects models to examine the association between PM exposures and log10-transformed HRV indices, adjusting for key personal and environmental attributes. We found that PM(0.3-1.0) exposures at 1- to 4-hr moving averages were associated with SDNN and r-MSSD in both cardiac and hypertensive patients. For an interquartile increase in PM(0.3-1.0), there were 1.49-4.88% decreases in SDNN and 2.73-8.25% decreases in r-MSSD. PM(0.3-1.0) exposures were also associated with decreases in LF and HF for hypertensive patients at 1- to 3-hr moving averages except for cardiac patients at moving averages of 2 or 3 hr. By contrast, we found that HRV was not associated with either PM(1.0-2.5) or PM(2.5-10). HRV reduction in susceptible population was associated with PM(0.3-1.0) but was not associated with either PM(1.0-2.5) or PM(2.5-10).
authors.affiliation: Institute of Occupational Medicine and Industrial Hygiene, College of Public Health, National Taiwan University, Taipei, Taiwan.
authors.forename: Kai-Jen
authors.initials: KJ
authors.lastname: Chuang
authors.forename: Chang-Chuan
authors.initials: CC
authors.lastname: Chan
authors.forename: Nan-Ting
authors.initials: NT
authors.lastname: Chen
authors.forename: Ta-Chen
authors.initials: TC
authors.lastname: Su
authors.forename: Lian-Yu
authors.initials: LY
authors.lastname: Lin
mesh_terms: D000368:Aged; D000393:Air Pollutants / Q000633:toxicity*; D003327:Coronary Disease / Q000503:physiopathology*; D004305:Dose-Response Relationship, Drug; D004562:Electrocardiography; D005260:Female; D006339:Heart Rate / Q000187:drug effects*; D006801:Humans; D006973:Hypertension / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D010316:Particle Size; D013624:Taiwan; D013997:Time Factors
chemical_list: D000393:Air Pollutants