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Randomized Controlled Trial
. 2014 Jul 16;11:31.
doi: 10.1186/s12989-014-0031-y.

Inhalation of Ultrafine Carbon Particles Alters Heart Rate and Heart Rate Variability in People With Type 2 Diabetes

Free PMC article
Randomized Controlled Trial

Inhalation of Ultrafine Carbon Particles Alters Heart Rate and Heart Rate Variability in People With Type 2 Diabetes

Rathin Vora et al. Part Fibre Toxicol. .
Free PMC article

Abstract

Background: Diabetes may confer an increased risk for the cardiovascular health effects of particulate air pollution, but few human clinical studies of air pollution have included people with diabetes. Ultrafine particles (UFP, ≤100 nm in diameter) have been hypothesized to be an important component of particulate air pollution with regard to cardiovascular health effects.

Methods: 17 never-smoker subjects 30-60 years of age, with stable type 2 diabetes but otherwise healthy, inhaled either filtered air (0-10 particles/cm3) or elemental carbon UFP (~107 particles/cm3, ~50 ug/m3, count median diameter 32 nm) by mouthpiece, for 2 hours at rest, in a double-blind, randomized, crossover study design. A digital 12-lead electrocardiogram (ECG) was recorded continuously for 48 hours, beginning 1 hour prior to exposure.

Results: Analysis of 5-minute segments of the ECG during quiet rest showed reduced high-frequency heart rate variability with UFP relative to air exposure (p = 0.014), paralleled by non-significant reductions in time-domain heart rate variability parameters. In the analysis of longer durations of the ECG, we found that UFP exposure increased the heart rate relative to air exposure. During the 21- to 45-hour interval after exposure, the average heart rate increased approximately 8 beats per minute with UFP, compared to 5 beats per minute with air (p = 0.045). There were no UFP effects on cardiac rhythm or repolarization.

Conclusions: Inhalation of elemental carbon ultrafine particles alters heart rate and heart rate variability in people with type 2 diabetes. Our findings suggest that effects may occur and persist hours after a single 2-hour exposure.

Figures

Figure 1
Figure 1
ECG changes recorded during pre-specified 5 minute segments. Mean ± SE change from pre-exposure baseline in heart rate (A), pNN50 (B), rMSSD (C), and HF (D) in subjects exposed to elemental carbon UFP (solid boxes) and filtered air (open circles), during and at specified time intervals after exposure. The insets show actual baseline values. P-value is for mixed models main effect of exposure.
Figure 2
Figure 2
ECG changes during longer monitoring periods. Mean ± SE change from first monitoring period (0–9 hours, which included the exposure and first few hours afterward) to subsequent 2 monitoring periods, in heart rate (A), SDNN (B), pNN50 (C), and rMSSD (D) in subjects exposed to elemental carbon UFP (solid boxes) and filtered air (open circles). The insets show actual mean values for the 0–9 hours monitoring period, which was used as the baseline. P-value is for mixed models main effect of exposure.
Figure 3
Figure 3
ECG changes during longer monitoring periods. Mean ± SE change from first monitoring period (0–9 hours, which included the exposure and first few hours afterward) to subsequent 2 monitoring periods, in the ST segment of the ECG for lead 2 (A), lead V2 (B), and lead V5 (C), in subjects exposed to elemental carbon UFP (solid boxes) and filtered air (open circles). The insets show actual mean values for the 0–9 hours monitoring period.

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