Acute exposure to environmental tobacco smoke and heart rate variability

Environmental tobacco smoke (ETS) has been associated with cardiovascular m ortality. Pathophysiologic pathways leading from ETS exposure to cardiopulm onary disease are still being explored. Reduced cardiac autonomic function, as measured by heart rate variability (HRV), has been associated with card iac vulnerability and may represent an important pathophysiologic mechanism linking ETS and risk of cardiac mortality. In this study we evaluated acut e ETS exposure in a commercial airport with changes in HRV in 16 adult nons mokers. We conducted ambulatory electrocardiographic (ECG) monitoring for 8 -hr periods while participants alternated 2 hr in nonsmoking and smoking ar eas. Nicotine and respirable suspended particle concentrations and particip ants' blood oxygen saturation were also monitored. We calculated time and f requency domain measures of HRV for periods in and out of the smoking area, and we evaluated associations with ETS using comparative statistics and re gression modeling. ETS exposure was negatively associated with all measures of HRV. During exposure periods, we observed an average decrement of appro ximately 12% in the standard deviation of all normal-to-normal heart beat i ntervals (an estimate of overall HRV). ETS exposures were not associated wi th mean heart rate or blood oxygen saturation. Altered cardiac autonomic fu nction, assessed by decrements in HRV, is associated with acute exposure to ETS and may be part of the pathophysiologic mechanisms linking ETS exposur e and increased cardiac vulnerability.