Elsevier

American Heart Journal

Volume 138, Issue 5, November 1999, Pages 890-899
American Heart Journal

Heart rate variability associated with particulate air pollution,☆☆,

https://doi.org/10.1016/S0002-8703(99)70014-1Get rights and content

Abstract

Background: Epidemiologic studies have linked fine particulate air pollution with cardiopulmonary mortality, yet underlying biologic mechanisms remain unknown. Changes in heart rate variability (HRV) may reflect changes in cardiac autonomic function and risk of sudden cardiac death. This study evaluated changes in mean heart rate and HRV in human beings associated with changes in exposure to particulate air pollution. Methods: Repeated ambulatory electrocardiographic monitoring was conducted on 7 subjects for a total of 29 person-days before, during, and after episodes of elevated pollution. Mean HR, the standard deviation of normal-to-normal (NN) intervals (SDNN), the standard deviation of the averages of NN intervals in all 5-minute segments of the recording (SDANN), and the square root of the mean of squared differences between adjacent NN intervals (r-MSSD) were calculated for 24-hour and 6-hour time segments. Associations of HRV with particulate pollution levels were evaluated with fixed-effects regression models. Results: After controlling for differences across patients, elevated particulate levels were associated with (1) increased mean HR, (2) decreased SDNN, a measure of overall HRV, (3) decreased SDANN, a measure that corresponds to ultralow frequency variability, and (4) increased r-MSSD, a measure that corresponds to high-frequency variability. The associations between HRV and particulates were small but persisted even after controlling for mean HR. Conclusions: This study suggests that changes in cardiac autonomic function reflected by changes in mean HR and HRV may be part of the pathophysiologic mechanisms or pathways linking cardiovascular mortality and particulate air pollution. (Am Heart J 1999;138:890-9.)

Section snippets

Study area, period, and patient selection

This study was conducted in the Utah Valley in central Utah (Figure 1).

. Study area, Utah Valley.

During frequent winter low-level temperature inversion episodes, particulate concentrations become elevated as local emissions are trapped in a stagnant air mass near the valley floor. Sources of particulate air pollution in the valley included an integrated steel mill, motor vehicle emissions, wood smoke, and others. The study area is approximately 1400 meters above sea level.

During the winter of

Results

Tables I and II provide summary information about the participants in the study and the mean HR and HRV data collected.

. Brief description of patients

PatientAgeSexMedical summaryPrescription medication
175MCongestive heart failure, hypertension, diabetesVerapamil, insulin, levothyroxine (Synthroid)
269FHypertension, angina, diabetes, congestive heart failureInsulin
389MAsthma, congestive heart failure, hypertension, diabetesFinasteride (Proscar), digoxin (Lanoxin), glyburide (Micronase)
477M

Discussion

Although epidemiologic investigations have observed that cardiopulmonary mortality is associated with particulate air pollution,1, 2 the underlying biologic mechanisms remain largely unknown. A potential general pathophysiologic pathway linking cardiopulmonary mortality and particulate air pollution includes fine particle pollution–induced lung damage (potentially including oxidative lung damage and inflammation), declines in lung function, respiratory distress, and potentially cardiovascular

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    Supported in part by Health Effects Institute, Cambridge, Mass, and the National Institute of Environmental Health Sciences (ES- 00002).

    ☆☆

    Reprint requests: C. Arden Pope III, PhD, 142 FOB, Brigham Young University, Provo, UT 84602. E-mail: [email protected]

    0002-8703/99/$8.00 + 0   4/1/99145

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