Air Pollution and Cardiac Arrhythmias in Patients with Implantable Cardioverter Defibrillators

Acute Impact of Fine Particulate Air Pollution on Cardiac Arrhythmias in a Population‐Based Sample of Adolescents: The Penn State Child Cohort

Background

Fine particulate (fine particles with aerodynamic diameters ≤2.5 μm [PM 2.5 ]) exposure has been associated with a risk of cardiac arrhythmias in adults. However, the association between PM 2.5 exposure and cardiac arrhythmias in adolescents remains unclear.

Methods and Results

To investigate the association and time course between PM 2.5 exposure with cardiac arrhythmias in adolescents, we analyzed the data collected from 322 adolescents who participated in the PSCC (Penn State Child Cohort) follow‐up examination. We obtained individual‐level 24‐hour PM 2.5 concentrations with a nephelometer. Concurrent with the PM 2.5 measure, we obtained 24‐hour ECG data using a Holter monitor, from which cardiac arrhythmias, including premature atrial contractions and premature ventricular contractions (PVCs), were identified. PM 2.5 concentration and numbers of premature atrial contractions/PVCs were summarized into 30‐minute‐based segments. Polynomial distributed lag models within a framework of a negative binomial model were used to assess the effect of PM 2.5 concentration on numbers of premature atrial contractions and PVCs. PM 2.5 exposure was associated with an acute increase in number of PVCs. Specifically, a 10 μg/m 3 increase in PM 2.5 concentration was associated with a 2% (95% CI, 0.4%–3.3%) increase in PVC counts 0.5 to 1.0, 1.0 to 1.5, and 1.5 to 2.0 hours after the exposure. Cumulatively, a 10 μg/m 3 increment in PM 2.5 was associated with a 5% (95% CI, 1%–10%) increase in PVC counts within 2 hours after exposure. PM 2.5 concentration was not associated with premature atrial contraction.

Conclusions

PM 2.5 exposure was associated with an acute increased number of ventricular arrhythmias in a population‐based sample of adolescents. The time course of the effect of PM 2.5 on ventricular arrhythmia is within 2 hours after exposure.

Do acute changes in ambient air pollution increase the risk of potentially fatal cardiac arrhythmias in patients with implantable cardioverter defibrillators?

BACKGROUND

Daily changes in ambient air pollution have been associated with cardiac morbidity and mortality. Precipitating a cardiac arrhythmia in susceptible individuals may be one mechanism. We investigated the influence of daily changes in air pollution in the Province of Ontario, Canada on the frequency of discharges from implantable cardio defibrillators (ICDs) which occur in response to potentially life threatening arrhythmias.

METHODS

Using a case- crossover design, we compared ambient air pollution concentrations on the day of an ICD discharge to other days in the same month and year in 1952 patients. We adjusted for weather, lagged the exposure data from 0 to 3 days, and stratified the results by several patient-related characteristics.

RESULTS

Median (interquartile range) for ozone (O₃), fine particulate matter (PM_2.5), sulphur dioxide (SO₂) and nitrogen dioxide (NO₂) were 26.0 ppb (19.4, 33.0), 6.6 μg/m³ (4.3, 10.6), 1.00 ppb (0.4,2.1), 10.0 ppb (6.0,15.3) respectively. Unlagged odds ratios (95%) for an ICD discharge associated with an interquartile range increase in pollutant were 0.97 (0.86, 1.09) for O₃, 0.99 (0.92, 1.06) for PM_2.5, 0.97 (0.91, 1.03) for SO₂, and 1.00 (0.89, 1.12) for NO₂.

CONCLUSION

We found no evidence that the concentrations of ambient air pollution observed in our study were a risk factor for potentially fatal cardiac arrhythmias in patients with ICDs.

Cardiovascular function and ozone exposure: The Multicenter Ozone Study in oldEr Subjects (MOSES)

BACKGROUND

To date, there have been relatively few studies of acute cardiovascular responses to controlled ozone inhalation, although a number of observational studies have reported significant positive associations between both ambient ozone levels and acute cardiovascular events and long-term ozone exposure and cardiovascular mortality.

OBJECTIVES

We hypothesized that short-term controlled exposure to low levels of ozone in filtered air would induce autonomic imbalance, repolarization abnormalities, arrhythmia, and vascular dysfunction.

METHODS

This randomized crossover study of 87 healthy volunteers 55-70 years of age was conducted at three sites using a common protocol, from June 2012 to April 2015. Subjects were exposed for 3 h in random order to 0 ppb (filtered air), 70 ppb ozone, and 120 ppb ozone, alternating 15 min of moderate exercise with 15 min of rest. A suite of cardiovascular endpoints was measured the day before, the day of, and up to 22 h after each exposure. Mixed effect linear and logit models evaluated the impact of exposure to ozone on pre-specified primary and secondary outcomes. Site and time were included in the models.

RESULTS

We found no significant effects of ozone exposure on any of the primary or secondary measures of autonomic function, repolarization, ST segment change, arrhythmia, or vascular function (systolic blood pressure and flow-mediated dilation).

CONCLUSIONS

In this multicenter study of older healthy women and men, there was no convincing evidence for acute effects of 3-h, relatively low-level ozone exposures on cardiovascular function. However, we cannot exclude the possibility of effects with higher ozone concentrations, more prolonged exposure, or in subjects with underlying cardiovascular disease. Further, we cannot exclude the possibility that exposure to ambient ozone and other pollutants in the days before the experimental exposures obscured or blunted cardiovascular biomarker response to the controlled ozone exposures.

Is smog innocuous? Air pollution and cardiovascular disease

Air pollution is a significant environmental and health hazard. Earlier studies had examined the adverse health effects associated with short- and long-term exposure to particulate matter on respiratory disease. However, later studies demonstrated that was actually cardiovascular disease that accounted for majority of mortality. Furthermore, it was not gaseous pollutants like oxides of nitrate, sulfur, carbon mono-oxide or ozone but the particulate matter or PM, of fine or coarse size (PM_2.5 and PM₁₀) which was linearly associated with mortality; PM_2.5 with long term and PM₁₀ with short term. Several cardiovascular diseases are associated with pollution; acute myocardial infarction, heart failure, cardiac arrhythmias, atherosclerosis and cardiac arrest. The ideal way to address this problem is by adhering to stringent environmental standards of pollutants but some individual steps like choosing to stay indoors (on high pollution days), reducing outdoor air permeation to inside, purifying indoor air using air filters, and also limiting outdoor physical activity near source of air pollution can help. Nutritional anti-oxidants like statins or Mediterranean diet, and aspirin have not been associated with reduced risk but specific nutritional agents like broccoli, cabbage, cauliflower or brussels sprouts, fish oil supplement may help. Use of face-mask has been controversial but may be useful if particulate matter load is higher.

Main air pollutants and ventricular arrhythmias in patients with implantable cardioverter-defibrillators: A systematic review and meta-analysis

Objective

Previous studies of ambient air pollutants and ventricular arrhythmias in patients with implantable cardioverter-defibrillator (ICD) have yielded mixed results, and the association between air pollution and ventricular arrhythmias in these patients remains unclear. This study aimed to assess and quantify the association between exposure to major air pollutants [CO, inhalable particles (PM₁₀), SO₂, fine particulate matter (PM_2.5), O₃, and NO₂] and the presence of ventricular arrhythmia in patients with ICD.

Methods

The Medline, PubMed, Web of Science, Global Health Library, Virtual Health Library, Population Information Online (POPLINE), and New York Academy of Medicine Grey Literature Report databases were searched to identify studies analyzing the association between ventricular arrhythmias in patients with ICD and the abovementioned main air pollutants. Pooled estimates were generated using a random-effects model or fixed-effects model, according to the value of heterogeneity. Heterogeneity within studies was assessed using Cochran's Q and I² statistics. Funnel plots, Egger's regression test, and Begg's rank correlation method were used to evaluate publication bias. Sensitivity analyses were also conducted to evaluate the potential sources of heterogeneity.

Results

After a detailed screening of 167 studies, seven separate studies were identified. Ventricular arrhythmias in patients with ICD were found to be positively, but not significantly, associated with CO, PM₁₀, SO₂, PM_2.5, and NO_2, with a pooled estimate [odds ratio (OR) associated with each 10 μg/m³ increase in pollutant concentration, except for CO, which was associated with each 1 mg/m³ increase in concentration] of 1.03 [95% confidence interval (CI): 0.92-1.17, P = 0.59] for CO, 1.01 (95%CI: 0.97-1.05, P = 0.55) for PM₁₀, 1.09 (95%CI: 0.95-1.24, P = 0.22) for SO_2, 1.07 (95%CI: 0.95-1.21, P = 0.25) for PM_2.5, and 1.06 (95%CI: 0.98-1.14, P = 0.16) for NO₂. No increased risk of ventricular arrhythmias in patients with ICD was found to be associated with O₃ (OR = 1.00; 95%CI: 0.98-1.01, P = 0.56).

Conclusions

The results of this study provide little evidence that ambient air pollutants affect the risk of ICD discharges for treating ventricular arrhythmias.

Association of air pollution sources and aldehydes with biomarkers of blood coagulation, pulmonary inflammation, and systemic oxidative stress

Using data collected before, during, and after the 2008 Summer Olympic Games in Beijing, this study examines associations between biomarkers of blood coagulation (vWF, sCD62P and sCD40L), pulmonary inflammation (EBC pH, EBC nitrite, and eNO), and systemic oxidative stress (urinary 8-OHdG) with sources of air pollution identified utilizing principal component analysis and with concentrations of three aldehydes of health concern. Associations between the biomarkers and the air pollution source types and aldehydes were examined using a linear mixed effects model, regressing through seven lag days and controlling for ambient temperature, relative humidity, gender, and day of week for the biomarker measurements. The biomarkers for pulmonary inflammation, particularly EBC pH and eNO, were most consistently associated with vehicle and industrial combustion, oil combustion, and vegetative burning. The biomarkers for blood coagulation, particularly vWF and sCD62p, were most consistently associated with oil combustion. Systemic oxidative stress biomarker (8-OHdG) was most consistently associated with vehicle and industrial combustion. The associations of the biomarkers were generally not significant or consistent with secondary formation of pollutants and with the aldehydes. The findings support policies to control anthropogenic pollution sources rather than natural soil or road dust from a cardio-respiratory health standpoint.

Short-Term Exposure to Air Pollution and Cardiac Arrhythmia: A Meta-Analysis and Systematic Review

The objective was to assess the transient association between air pollution and cardiac arrhythmia. Five databases were searched for studies investigating the association between daily increases in air pollutants (PM2.5, PM10, carbon monoxide, nitrogen dioxide, sulfur dioxide and ozone) and arrhythmia hospitalization or arrhythmia mortality. Two reviewers independently selected studies, extracted data, and assessed risk of bias. Outcomes were analyzed via a random-effects model and reported as relative risk and 95% confidence interval. 25 studies satisfied our inclusion criteria and 23 contributed to the meta-analysis. Arrhythmia hospitalization or mortality were associated with increases in PM2.5 (RR = 1.015 per 10 μg/m³, 95% CI: 1.006-1.024), PM10 (RR = 1.009 per 10 μg/m³, 95% CI: 1.004-1.014), carbon monoxide (RR = 1.041 per 1 ppm, 95% CI: 1.017-1.065), nitrogen dioxide (RR = 1.036 per 10 ppb, 95% CI: 1.020-1.053), and sulfur dioxide (RR = 1.021 per 10 ppb, 95% CI: 1.003-1.039), but not ozone (RR = 1.012 per 10 ppb, 95% CI: 0.997-1.027). Both particulate and gaseous components, with the exception of ozone, have a temporal association with arrhythmia hospitalization or mortality. Compared with Europe and North America, a stronger association was noted in Asia.

Environmental and occupational particulate matter exposures and ectopic heart beats in welders

OBJECTIVES

Links between arrhythmias and particulate matter exposures have been found among sensitive populations. We examined the relationship between personal particulate matter ≤2.5 µm aerodynamic diameter (PM2.5) exposures and ectopy in a panel study of healthy welders.

METHODS

Simultaneous ambulatory ECG and personal PM2.5 exposure monitoring with DustTrak Aerosol Monitor was performed on 72 males during work and non-work periods for 5-90 h (median 40 h). ECGs were summarised hourly for supraventricular ectopy (SVE) and ventricular ectopy (VE). PM2.5 exposures both work and non-work periods were averaged hourly with lags from 0 to 7 h. Generalised linear mixed-effects models with a random participant intercept were used to examine the relationship between PM2.5 exposure and the odds of SVE or VE. Sensitivity analyses were performed to assess whether relationships differed by work period and among current smokers.

RESULTS

Participants had a mean (SD) age of 38 (11) years and were monitored over 2993 person-hours. The number of hourly ectopic events was highly skewed with mean (SD) of 14 (69) VE and 1 (4) SVE. We found marginally significant increases in VE with PM2.5 exposures in the sixth and seventh hour lags, yet no association with SVE. For every 100 μg/m(3) increase in sixth hour lagged PM2.5, the adjusted OR (95% CI) for VE was 1.03 (1.00 to 1.05). Results persisted in work or non-work exposure periods and non-smokers had increased odds of VE associated with PM2.5 as compared with smokers.

CONCLUSIONS

A small increase in the odds of VE with short-term PM2.5 exposure was observed among relatively healthy men with environmental and occupational exposures.

Impact of Fine Particulate Matter (PM2.5) Exposure During Wildfires on Cardiovascular Health Outcomes

Background

Epidemiological studies investigating the role of fine particulate matter (PM_2.5; aerodynamic diameter <2.5 μm) in triggering acute coronary events, including out-of-hospital cardiac arrests and ischemic heart disease (IHD), during wildfires have been inconclusive.

Methods and Results

We examined the associations of out-of-hospital cardiac arrests, IHD, acute myocardial infarction, and angina (hospital admissions and emergency department attendance) with PM_2.5 concentrations during the 2006–2007 wildfires in Victoria, Australia, using a time-stratified case-crossover study design. Health data were obtained from comprehensive health-based administrative registries for the study period (December 2006 to January 2007). Modeled and validated air exposure data from wildfire smoke emissions (daily average PM_2.5, temperature, relative humidity) were also estimated for this period. There were 457 out-of-hospital cardiac arrests, 2106 emergency department visits, and 3274 hospital admissions for IHD. After adjusting for temperature and relative humidity, an increase in interquartile range of 9.04 μg/m³ in PM_2.5 over 2 days moving average (lag 0-1) was associated with a 6.98% (95% CI 1.03% to 13.29%) increase in risk of out-of-hospital cardiac arrests, with strong association shown by men (9.05%,95%CI 1.63% to 17.02%) and by older adults (aged ≥65 years) (7.25%, 95% CI 0.24% to 14.75%). Increase in risk was (2.07%, 95% CI 0.09% to 4.09%) for IHD-related emergency department attendance and (1.86%, 95% CI: 0.35% to 3.4%) for IHD-related hospital admissions at lag 2 days, with strong associations shown by women (3.21%, 95% CI 0.81% to 5.67%) and by older adults (2.41%, 95% CI 0.82% to 5.67%).

Conclusion

PM_2.5 exposure was associated with increased risk of out-of-hospital cardiac arrests and IHD during the 2006–2007 wildfires in Victoria. This evidence indicates that PM_2.5 may act as a triggering factor for acute coronary events during wildfire episodes.

Weight-of-evidence evaluation of short-term ozone exposure and cardiovascular effects

There is a relatively large body of research on the potential cardiovascular (CV) effects associated with short-term ozone exposure (defined by EPA as less than 30 days in duration). We conducted a weight-of-evidence (WoE) analysis to assess whether it supports a causal relationship using a novel WoE framework adapted from the US EPA's National Ambient Air Quality Standards causality framework. Specifically, we synthesized and critically evaluated the relevant epidemiology, controlled human exposure, and experimental animal data and made a causal determination using the same categories proposed by the Institute of Medicine report Improving the Presumptive Disability Decision-making Process for Veterans ( IOM 2008). We found that the totality of the data indicates that the results for CV effects are largely null across human and experimental animal studies. The few statistically significant associations reported in epidemiology studies of CV morbidity and mortality are very small in magnitude and likely attributable to confounding, bias, or chance. In experimental animal studies, the reported statistically significant effects at high exposures are not observed at lower exposures and thus not likely relevant to current ambient ozone exposures in humans. The available data also do not support a biologically plausible mechanism for CV effects of ozone. Overall, the current WoE provides no convincing case for a causal relationship between short-term exposure to ambient ozone and adverse effects on the CV system in humans, but the limitations of the available studies preclude definitive conclusions regarding a lack of causation. Thus, we categorize the strength of evidence for a causal relationship between short-term exposure to ozone and CV effects as "below equipoise."

The effects of B0, B20, and B100 soy biodiesel exhaust on aconitine-induced cardiac arrhythmia in spontaneously hypertensive rats

CONTEXT

Diesel exhaust (DE) has been shown to increase the risk of cardiac arrhythmias. Although biodiesel has been proposed as a "safer" alternative to diesel, it is still uncertain whether it actually poses less threat.

OBJECTIVE

We hypothesized that exposure to pure or 20% soy biodiesel exhaust (BDE) would cause less sensitivity to aconitine-induced arrhythmia than DE in rats.

METHODS

Spontaneously hypertensive (SH) rats implanted with radiotelemeters were exposed once or for 5 d (4 h) to either 50 mg/m(3) (low), 150 mg/m(3) (medium), or 500 mg/m(3) (high) of DE (B0), 20% (B20) or 100% (B100) soy biodiesel exhaust. Arrhythmogenesis was assessed 24 h later by continuous infusion of aconitine, an arrhythmogenic drug, while heart rate (HR), and electrocardiogram (ECG) were monitored.

RESULTS

Rats exposed once or for 5 d to low, medium, or high B0 developed arrhythmia at significantly lower doses of aconitine than controls, whereas rats exposed to B20 were only consistently sensitive after 5 d of the high concentration. B100 caused mild arrhythmia sensitivity at the low concentration, only after 5 d of exposure at the medium concentration and after either a single or 5 d at the high concentration.

DISCUSSION AND CONCLUSIONS

These data demonstrate that exposure to B20 causes less sensitivity to arrhythmia than B0 and B100. This diminished effect may be due to lower irritant components such as acrolein and nitrogen oxides. Thus, in terms of cardiac health, B20 may be a safer option than both of the pure forms.

Cardiorespiratory treatments as modifiers of the relationship between particulate matter and health: a case-only analysis on hospitalized patients in Italy

BACKGROUND

A few panel and toxicological studies suggest that health effects of particulate matter (PM) might be modified by medication intake, but whether this modification is confirmed in the general population or for more serious outcomes is still unknown.

OBJECTIVES

We carried out a population-based pilot study in order to assess how pre-hospitalization medical treatments modify the relationship between PM<10 μm in aerodynamic diameter (PM10) and the risk of cardiorespiratory admission.

METHODS

We gathered information on hospitalizations for cardiorespiratory causes, together with pre-admission pharmacological treatments, that occurred during 2005 in seven cities located in Lombardy (Northern Italy). City-specific PM10 concentrations were measured at fixed monitoring stations. Each treatment of interest was analyzed separately through a case-only approach, using generalized additive models accounting for sex, age, comorbidities, temperature and simultaneous intake of other drugs. Analyses were stratified by season and, if useful, by age and sex.

RESULTS

Our results showed a higher effect size for PM10 on respiratory admissions in subjects treated with theophylline (Odds Ratio (OR) of treatment for an increment of 10 μg/m(3) in PM10 concentration: 1.119; 95% Confidence Interval (CI): 1.013-1.237), while for cardiovascular admissions treatment with cardiac therapy (OR: 0.967, 95% CI: 0.940-0.995) and lipid modifying agents (OR: 0.962, 95% CI: 0.931-0.995) emerged as a protective factor, especially during the warm season. Evidence of a protective effect against the pollutant was found for glucocorticoids and respiratory admissions.

CONCLUSIONS

Our study showed that the treatment with cardiac therapy and lipid modifying agents might mitigate the effect of PM10 on cardiovascular health, while the use of theophylline seems to enhance the effect of the pollutant, possibly due to confounding by indication. It is desirable to extend the analyses to a larger population.

The association between ambient air quality and cardiac rate and rhythm in ambulatory subjects

BACKGROUND

Acute increases in ambient air pollution have been associated with increased hospitalization for cardiac diseases and stroke. Triggering of cardiac arrhythmia by changes in air quality could theoretically predispose individuals to cardiac arrest or heart failure, or stroke through precipitation of atrial fibrillation. We investigated the association between air quality and cardiac rate and rhythm characteristics measured by ambulatory cardiac monitoring.

METHODS AND RESULTS

Daily ambient 3-h maximum concentrations of ozone, nitrogen dioxide and fine particulate matter, and an index summarizing these pollutants called the Air Quality Health Index (AQHI) were compared to the results of 24-h ambulatory cardiac monitoring performed for clinical purposes in 8662 patients and analyzed at the University of Ottawa Heart Institute, Canada, between 2004 and 2009. An interquartile increase in the daily 3 h- maximum AQHI was associated with a 0.9% (95% CI 0.3%, 1.5%) increase in the daily maximum heart rate and a 1.17% (95% CI 1.07%, 1.29%) increase in heart block frequency. An interquartile increase in NO2 was associated with an increase in the percentage of time in atrial fibrillation of 4.39% (-0.15, 9.15) among those ≤50 years old, and 7.1% (0.24, 14.5) among males.

CONCLUSIONS

We found evidence that air pollution may affect cardiac rate and rhythm. This may be one mechanism partially explaining the increase in strokes and cardiac events observed on days of higher air pollution.

Controlled exposures to air pollutants and risk of cardiac arrhythmia

BACKGROUND

Epidemiological studies have reported associations between air pollution exposure and increases in cardiovascular morbidity and mortality. Exposure to air pollutants can influence cardiac autonomic tone and reduce heart rate variability, and may increase the risk of cardiac arrhythmias, particularly in susceptible patient groups.

OBJECTIVES

We investigated the incidence of cardiac arrhythmias during and after controlled exposure to air pollutants in healthy volunteers and patients with coronary heart disease.

METHODS

We analyzed data from 13 double-blind randomized crossover studies including 282 participants (140 healthy volunteers and 142 patients with stable coronary heart disease) from whom continuous electrocardiograms were available. The incidence of cardiac arrhythmias was recorded for each exposure and study population.

RESULTS

There were no increases in any cardiac arrhythmia during or after exposure to dilute diesel exhaust, wood smoke, ozone, concentrated ambient particles, engineered carbon nanoparticles, or high ambient levels of air pollution in either healthy volunteers or patients with coronary heart disease.

CONCLUSIONS

Acute controlled exposure to air pollutants did not increase the short-term risk of arrhythmia in participants. Research employing these techniques remains crucial in identifying the important pathophysiological pathways involved in the adverse effects of air pollution, and is vital to inform environmental and public health policy decisions.

Ecological study on hospitalizations for cancer, cardiovascular, and respiratory diseases in the industrial area of Etang-de-Berre in the South of France

The Etang-de-Berre area is a large industrialized area in the South of France, exposing 300,000 inhabitants to the plumes of its industries. The possible associated health risks are of the highest concern to the population, who asked for studies investigating their health status. A geographical ecological study based on standardized hospitalizations ratios for cancer, cardiovascular, and respiratory diseases was carried out over the 2004–2007 period. Exposure to air pollution was assessed using dispersion models coupled with a geographic information system to estimate an annual mean concentration of sulfur dioxide (SO₂) for each district. Results showed an excess risk of hospitalization for myocardial infarction in women living in districts with medium or high SO₂ exposure, respectively, 38% [CI 95% 4 : 83] and 54% [14 : 110] greater than women living in districts at the reference level exposure. A 26% [2 : 57] excess risk of hospitalization for myocardial infarction was also observed in men living in districts with high SO₂ levels. No excess risk of hospitalization for respiratory diseases or for cancer was observed, except for acute leukemia in men only. Results illustrate the impact of industrial air pollution on the cardiovascular system and call for an improvement of the air quality in the area.

Short-term effects of fine particulate air pollution on emergency room visits for cardiac arrhythmias: a case-crossover study in Taipei

This study was undertaken to determine whether there was an association between fine particles (PM₂.₅) levels and number of emergency room (ER) visits for cardiac arrhythmias in Taipei, Taiwan. ER visits for cardiac arrhythmias and ambient air pollution data for Taipei were obtained for the period 2006-2010. The relative risk (RR) of ER visits was estimated using a case-crossover approach, controlling for weather variables, day of the week, seasonality, and long-term time trends. For the single-pollutant model (without adjustment for other pollutants), increased numbers of ER cardiac arrhythmia visits were significantly associated with PM₂.₅ on both warm days (>23°C) and cool days (< 23°C), with an interquartile range rise associated with a 10% (95% CI = -15%) and 4% (95% CI = 0-8%) elevation in number of ER visits for cardiac arrhythmias, respectively. In the two-pollutant models, PM₂.₅ levels remained significant after inclusion of sulfur dioxide (SO₂) or ozone (O₃) on both warm and cool days. This study provides evidence that higher levels of PM₂.₅ increase the risk of number of ER visits for cardiac arrhythmias.

Air pollution and arrhythmic risk: the smog is yet to clear

Epidemiologic evidence has demonstrated that air pollution may impair cardiovascular health, leading to potentially life-threatening arrhythmias. Efforts have been made, with the use of epidemiologic data and controlled exposures in diverse animal and human populations, to verify the relationship between air pollution and arrhythmias. The purpose of this review is to examine and contrast the epidemiologic and toxicologic evidence to date that relates airborne pollutants with cardiac arrhythmia. We have explored the potential biological mechanisms driving this association. Using the PubMed database, we conducted a literature search that included the terms "air pollution" and "arrhythmia" and eventually divergent synonyms such as "particulate matter," "bradycardia," and "atrial fibrillation." We reviewed epidemiologic studies and controlled human and animal exposures independently to determine whether observational conclusions were corroborated by toxicologic results. Numerous pollutants have demonstrated some arrhythmic capacity among healthy and health-compromised populations. However, some exposure studies have shown no significant correlation of air pollutants with arrhythmia, which suggests some uncertainty about the arrhythmogenic potential of air pollution and the mechanisms involved in arrhythmogenesis. While data from an increasing number of controlled exposures with human volunteers suggest a potential mechanistic link between air pollution and altered cardiac electrophysiology, definite conclusions regarding air pollution and arrhythmia are elusive as the direct arrhythmic effects of air pollutants are not entirely consistent across all studies.

Acute effects of fine particulate air pollution on cardiac arrhythmia: the APACR study

BACKGROUND

The mechanisms underlying the relationship between particulate matter (PM) air pollution and cardiac disease are not fully understood.

OBJECTIVES

We examined the effects and time course of exposure to fine PM [aerodynamic diameter ≤ 2.5 μm (PM(2.5))] on cardiac arrhythmia in 105 middle-age community-dwelling healthy nonsmokers in central Pennsylvania.

METHODS

The 24-hr beat-to-beat electrocardiography data were obtained using a high-resolution Holter system. After visually identifying and removing artifacts, we summarized the total number of premature ventricular contractions (PVCs) and premature atrial contractions (PACs) for each 30-min segment. A personal PM(2.5) nephelometer was used to measure individual-level real-time PM(2.5) exposures for 24 hr. We averaged these data to obtain 30-min average time-specific PM(2.5) exposures. Distributed lag models under the framework of negative binomial regression and generalized estimating equations were used to estimate the rate ratio between 10-μg/m³ increases in average PM(2.5) over 30-min intervals and ectopy counts.

RESULTS

The mean ± SD age of participants was 56 ± 8 years, with 40% male and 73% non-Hispanic white. The 30-min mean ± SD for PM(2.5) exposure was 13 ± 22 μg/m³, and PAC and PVC counts were 0.92 ± 4.94 and 1.22 ± 7.18. Increases of 10 μg/m³ in average PM(2.5) concentrations during the same 30 min or the previous 30 min were associated with 8% and 3% increases in average PVC counts, respectively. PM(2.5) was not significantly associated with PAC count.

CONCLUSION

PM(2.5) exposure within approximately 60 min was associated with increased PVC counts in healthy individuals.

Acute effects of fine particulate air pollution on ST segment height: a longitudinal study

BACKGROUND

The mechanisms for the relationship between particulate air pollution and cardiac disease are not fully understood. Air pollution-induced myocardial ischemia is one of the potentially important mechanisms.

METHODS

We investigate the acute effects and the time course of fine particulate pollution (PM2.5) on myocardium ischemic injury as assessed by ST-segment height in a community-based sample of 106 healthy non-smokers. Twenty-four hour beat-to-beat electrocardiogram (ECG) data were obtained using a high resolution 12-lead Holter ECG system. After visually identifying and removing all the artifacts and arrhythmic beats, we calculated beat-to-beat ST-height from ten leads (inferior leads II, III, and aVF; anterior leads V3 and V4; septal leads V1 and V2; lateral leads I, V5, and V6,). Individual-level 24-hour real-time PM2.5 concentration was obtained by a continuous personal PM2.5 monitor. We then calculated, on a 30-minute basis, the corresponding time-of-the-day specific average exposure to PM2.5 for each participant. Distributed lag models under a linear mixed-effects models framework were used to assess the regression coefficients between 30-minute PM2.5 and ST-height measures from each lead; i.e., one lag indicates a 30-minute separation between the exposure and outcome.

RESULTS

The mean (SD) age was 56 (7.6) years, with 41% male and 74% white. The mean (SD) PM2.5 exposure was 14 (22) μg/m3. All inferior leads (II, III, and aVF) and two out of three lateral leads (I and V6), showed a significant association between higher PM2.5 levels and higher ST-height. Most of the adverse effects occurred within two hours after PM2.5 exposure. The multivariable adjusted regression coefficients β (95% CI) of the cumulative effect due to a 10 μg/m3 increase in Lag 0-4 PM2.5 on ST-I, II, III, aVF and ST-V6 were 0.29 (0.01-0.56) μV, 0.79 (0.20-1.39) μV, 0.52 (0.01-1.05) μV, 0.65 (0.11-1.19) μV, and 0.58 (0.07-1.09) μV, respectively, with all p < 0.05.

CONCLUSIONS

Increased PM2.5 concentration is associated with immediate increase in ST-segment height in inferior and lateral leads, generally within two hours. Such an acute effect of PM2.5 may contribute to increased potential for regional myocardial ischemic injury among healthy individuals.

Air pollution and activation of implantable cardioverter defibrillators in London

BACKGROUND

Air pollution may increase the incidence of ventricular cardiac arrhythmias. We investigated this in patients with implantable cardioverter defibrillators attending London clinics.

METHOD

We explored associations between dates of activation of defibrillators and daily concentrations of various metrics of particulate matter and of pollutant gases at lags from 0 to 5 days, using a fixed-stratum case-crossover analysis controlling for confounding factors.

RESULTS

Over an average of 1200 days of observation, 705 patients experienced 5462 activation days. Of 11 pollutants considered, we found positive associations with particle sulfate, particulate matter with aerodynamic diameter less than 10 microm and less than 2.5 microm, ozone, and sulfur dioxide. Only the association for particle sulfate was not easily explainable by chance (for 1 microg/m, lag 0-1 day, odds ratio = 1.025 [95% confidence interval = 1.003 to 1.047]). There was little or no evidence of associations with markers of primary vehicle emissions (particle number concentration, black smoke, nitrogen oxides, and carbon monoxide). There was little evidence of interactions with clinical factors such as ischemic heart disease, frequency of activation, or cardiac drugs.

CONCLUSION

Overall there was little evidence of an association between air pollution and activation of implantable cardioverter defibrillators. The pollutants with positive associations tended to be those of secondary origin with a regional distribution, rather than primary pollutants emitted from transport sources.

Air pollution and emergency room visits for cardiac arrhythmia in a subtropical city: Taipei, Taiwan

This study was undertaken to determine whether there was an association between air pollutant levels and emergency room (ER) visits for cardiac arrhythmia in Taipei, Taiwan. ER visits for cardiac arrhythmia and ambient air pollution data for Taipei were obtained for the period 2000-2006. The relative risk of ER visits was estimated using a case-crossover approach, controlling for weather variables, day of the week, seasonality, and long-term time trends. In the single-pollutant model, on warm days (> or =23 degrees C), statistically significant positive associations were found for all pollutants except SO(2). On cool days (<23 degrees C), all pollutants were also significantly associated with the number of ER visits for cardiac arrhythmia, except SO(2). For the two-pollutant model, results for O(3) and NO(2) remained statistically significant on both warm and cool days. This study provides evidence that higher levels of ambient air pollutants increase the risk of ER visits for cardiac arrhythmia.

Particulate matter air pollution and cardiovascular disease: An update to the scientific statement from the American Heart Association

In 2004, the first American Heart Association scientific statement on "Air Pollution and Cardiovascular Disease" concluded that exposure to particulate matter (PM) air pollution contributes to cardiovascular morbidity and mortality. In the interim, numerous studies have expanded our understanding of this association and further elucidated the physiological and molecular mechanisms involved. The main objective of this updated American Heart Association scientific statement is to provide a comprehensive review of the new evidence linking PM exposure with cardiovascular disease, with a specific focus on highlighting the clinical implications for researchers and healthcare providers. The writing group also sought to provide expert consensus opinions on many aspects of the current state of science and updated suggestions for areas of future research. On the basis of the findings of this review, several new conclusions were reached, including the following: Exposure to PM <2.5 microm in diameter (PM(2.5)) over a few hours to weeks can trigger cardiovascular disease-related mortality and nonfatal events; longer-term exposure (eg, a few years) increases the risk for cardiovascular mortality to an even greater extent than exposures over a few days and reduces life expectancy within more highly exposed segments of the population by several months to a few years; reductions in PM levels are associated with decreases in cardiovascular mortality within a time frame as short as a few years; and many credible pathological mechanisms have been elucidated that lend biological plausibility to these findings. It is the opinion of the writing group that the overall evidence is consistent with a causal relationship between PM(2.5) exposure and cardiovascular morbidity and mortality. This body of evidence has grown and been strengthened substantially since the first American Heart Association scientific statement was published. Finally, PM(2.5) exposure is deemed a modifiable factor that contributes to cardiovascular morbidity and mortality.

Air pollution and the triggering of cardiac arrhythmias

PURPOSE OF REVIEW

The last 5 years have witnessed an explosion in interest regarding cardiac arrhythmias and air pollution. The data have been strongest with respect to ventricular arrhythmias but there is accumulating evidence that air pollution is also associated with supraventricular arrhythmias.

RECENT FINDINGS

There is clear epidemiological evidence linking air pollution and cardiac mortality. Whether the cardiac mortality was from myocardial ischemia, congestive heart failure or arrhythmic, or all of these pathways, is not clear from the epidemiological data. There is a large body of evidence that air pollution can modify autonomic tone. More recent data, utilizing patients with cardiac disease and implantable cardioverter defibrillators (ICDs), have clarified the association of air pollution and arrhythmias. Data are also accumulating that air pollution may be associated with atrial arrhythmias.

SUMMARY

The incremental risk of air pollution in triggering arrhythmias or other acute cardiac events is greatest for those patients with underlying cardiac disease. Cardiovascular patients and those at high risk of cardiovascular disease should be educated about the risks for triggering of arrhythmias and other cardiac events by air pollution. These patients should monitor the local forecasted Air Quality Index and follow the recommendations to reduce exposures and limit activities.

Ambient particulate air pollution and ectopy--the environmental epidemiology of arrhythmogenesis in Women's Health Initiative Study, 1999-2004

The relationships between ambient PM(2.5) and PM(10) and arrhythmia and the effect modification by cigarette smoking were investigated. Data from U.S. Environmental Protection Agency (EPA) air quality monitors and an established national-scale, log-normal kriging method were used to spatially estimate daily mean concentrations of PM at addresses of 57,422 individuals from 59 examination sites in 24 U.S. states in 1999-2004. The acute and subacute exposures were estimated as mean, geocoded address-specific PM concentrations on the day of, 0-2 d before, and averaged over 30 d before the electrocardiogram (ECG) (Lag(0); Lag(1); Lag(2); Lag(1-30)). At the time of standard 12-lead resting ECG, the mean age (SD) of participants was 67.5 (6.9) yr (84% non-Hispanic White; 6% current smoker; 15% with coronary heart disease; 5% with ectopy). After the identification of significant effect modifiers, two-stage random-effects models were used to calculate center-pooled odds ratios and 95% confidence intervals (OR, 95% CI) of arrhythmia per 10 mug/m(3) increase in PM concentrations. Among current smokers, Lag(0) and Lag(1) PM concentrations were significantly associated ventricular ectopy (VE)-the OR (95% CI) for VE among current smokers was 2 (1.32-3.3) and 1.32 (1.07-1.65) at Lag(1) PM(2.5) and PM(10), respectively. The interactions between current smoking and acute exposures (Lag(0); Lag(1); Lag(2)) were significant in relationship to VE. Acute exposures were not significantly associated with supraventricular ectopy (SVE), or with VE among nonsmokers. Subacute (Lag(1-30)) exposures were not significantly associated with arrhythmia. Acute PM(2.5) and PM(10) exposure is directly associated with the odds of VE among smokers, suggesting that they are more vulnerable to the arrhythmogenic effects of PM.

Air pollution and emergency room visits for arrhythmias: are there potentially sensitive groups?

Recent studies showed that air pollution is a risk factor for hospitalization for arrhythmias. However, there is limited evidence to suggest which subpopulations are at higher risk for arrhythmia development due to increased air pollutant exposure. This study was undertaken to examine the modifying effect of specific secondary diagnosis (including hypertension, diabetes, and congestive heart failure) on the relationship between frequency of emergency room (ER) visits for arrhythmias and ambient air pollutants concentrations. ER visits for arrhythmias and ambient air pollution data for Taipei were obtained for the period 2000-2006. The relative risk of ER visits was estimated using a case-crossover approach. Data showed an increased risk of ER visits for arrhythmias in relation to increased O(3) levels among individuals with a secondary diagnosis of hypertension and congestive heart failure.

Rapid effects of air pollution on ventricular arrhythmias

AIMS

Air pollution has been associated with ventricular arrhythmias in patients with implantable cardioverter defibrillators (ICDs) for exposure periods of 24-48 h. Only two studies have investigated exposure periods <24 h. We aimed to explore such effects during the 2 and 24 preceding hours as well as in relation to distance from the place of the event to the air pollution monitor.

METHODS AND RESULTS

We used a case-crossover design to investigate the effects of particulate matter <10 microm in diameter (PM10) and nitrogen dioxide (NO2) in 211 patients with ICD devices in Gothenburg and Stockholm, Sweden. Events interpreted as ventricular arrhythmias were downloaded from the ICDs, and air pollution data were collected from urban background monitors. We found an association between 2 h moving averages of PM10 and ventricular arrhythmia [odds ratio (OR) 1.31, 95% confidence interval (CI) 1.00-1.72], whereas the OR for 24 h moving averages was 1.24 (95% CI 0.87-1.76). Corresponding ORs for events occurring closest to the air pollution monitor were 1.76 (95% CI 1.18-2.61) and 1.74 (95% CI 1.07-2.84), respectively. Events occurring in Gothenburg showed stronger associations than in Stockholm.

CONCLUSION

Moderate increases in air pollution appear to be associated with ventricular arrhythmias in ICD patients already after 2 h, although future studies including larger numbers of events are required to confirm these findings. Representative geographical exposure classification seems important in studies of these effects.

A Case-Crossover Analysis of Particulate Air Pollution and Cardiac Arrhythmia in Patients with Implantable Cardioverter Defibrillators

We investigated the relationship between air pollution and incidence of cardiac arrhythmia in a study of patients with implantable cardioverter defibrillators (ICDs). Thirty-four patients (ages 15-85 yr, 80% male) with ICDs residing in the Vancouver, Canada, area were included in the analyses, representing all patients attending the 2 ICD clinics in the study region who had recorded at least 1 ICD discharge during the 14 February to 31 December 2000 study period. Air pollutant (PM(2.5), PM(10), SO(4)(2-), elemental carbon [EC], organic carbon [OC], O(3), SO(2), NO(2), and CO) concentrations on days for which ICD discharges were observed ("case days") were compared to concentrations on control days in case-crossover analyses. Control days were selected symmetrically, 7 days before and after each case day. ICD discharges occurring within 72 h of 1 another were grouped and considered as 1 discharge event. Temperature, relative humidity, barometric pressure, rainfall, and wind speed were included simultaneously as covariates. Sensitivity analyses examined the effect of grouping ICD discharges, of including meteorological variables, and of excluding discharges that were considered inappropriate by a cardiologist. As in previous studies, mean concentrations and interquartile ranges of air pollutants in Vancouver were low (e.g., PM(2.5) mean = 8.2 microg/m(3)). Although in general there were no statistically significant results, there were trends that might indicate associations between pollutants and ICD discharges. Odds ratios (OR) were consistently higher in summer than in winter (e.g., lag 0 per interquartile range increase in EC: 1.09 [0.86-1.37] vs. 0.61 [0.31-1.18]) and, in general, the highest ORs were observed for same-day effects. The one major exception was the observation of high ORs for ozone in winter (e.g., lag 1: 2.27 [0.67-7.66]). While an OR of 1.55 (0.51-4.70) was observed in summer at lag 0 for PM(10), no indications of positive associations were observed for PM(2.5) or SO(4)(2-). For indicators of local combustion-source pollution, EC, OC, CO, and SO(2), ORs were elevated at all lags (0-3 days) in summer. In summary, this study provides little evidence that specific components of PM affect risk of cardiac arrhythmias, although power limited the ability of the study to detect small effects.

Right heart pressure increases after acute increases in ambient particulate concentration

OBJECTIVES

We explored the association between acute changes in daily mean pulmonary artery (PA) and right ventricular (RV) pressures and concentrations of ambient fine particulate matter [PM with aerodynamic diameter < or = 2.5 microm (PM(2.5))] as an explanation for previous associations between congestive heart failure (HF) hospital admissions and PM.

MATERIALS AND METHODS

In the Chronicle Offers Management to Patients with Advanced Signs and Symptoms of Heart Failure (COMPASS-HF) trial, to see whether management of ambulatory HF could be improved by providing continuous right heart pressure monitoring to physicians, the Chronicle Implantable Hemodynamic Monitor (Medtronic, Inc., Minneapolis, MN, USA) continuously measured multiple right heart hemodynamic parameters, heart rate, and activity trends in subjects with moderate/severe HF. Using these trial data, we calculated daily mean pressures, using only those time intervals where the subject was not physically active (n = 5,807 person-days; n = 11 subjects). We then studied the association between mean daily PA/RV pressures and mean ambient PM(2.5) concentrations on the same day and previous 6 days.

RESULTS

Each 11.62-microg/m(3) increase in same-day mean PM(2.5) concentration was associated with small but significant increases in estimated PA diastolic pressure [0.19 mmHg; 95% confidence interval (CI), 0.05-0.33] and RV diastolic pressure (0.23 mmHg; 95% CI, 0.11-0.34). Although we saw considerable differences in the magnitude of response by COMPASS-HF randomization group (total data access for physicians vs. blocked clinician access), season, left ventricular ejection fraction, and obesity, these effects were not significantly different.

CONCLUSIONS

These pilot study findings provide a potential mechanism for previous findings of increased risk of HF associated with ambient PM. However, because of the small number of subjects, a larger study is needed for confirmation.

Ambient air pollution and cardiac arrhythmias in patients with implantable defibrillators

BACKGROUND

Previous studies of ambient air pollution and ventricular tachyarrhythmias in patients with implantable cardioverter defibrillators have yielded mixed results.

METHODS

We examined this relationship in a study of 518 patients with 6287 tachyarrhythmic event-days over a 10-year period in Atlanta, Georgia. The air quality data included daily measurements of PM10, ozone, nitrogen dioxide, carbon monoxide, and sulfur dioxide for the entire study period, as well as speciated measurements of PM2.5 mass and oxygenated hydrocarbons for the final 4 years of the study. Our primary analyses utilized generalized estimating equations, controlling for long-term time trends and meteorologic conditions as well as residual correlation within subjects.

RESULTS

Our primary modeling approach found no association; additional sensitivity analyses and alternative analytic approaches supported those findings. The most suggestive positive findings were for coarse particles.

CONCLUSIONS

The present study constitutes the largest study to date of ambient air pollution and tachyarrhythmic events in patients with implantable cardioverter defibrillators. Other than the suggestive findings for coarse particles, the study provides little evidence of an association between ambient air quality levels and tachyarrhythmic events.

Sulfur dioxide derivatives modulate Na/Ca exchange currents and cytosolic [Ca2+]i in rat myocytes

We have recently shown that sulfur dioxide (SO(2)) derivatives (bisulfite and sulfite, 1:3 M/M) modulated L-type calcium, sodium, and potassium channels in rat myocytes. The aim of this study was to investigate whether SO(2) derivatives could alter Na/Ca exchanger current and the intracellular free [Ca(2+)]. The nickel-sensitive Na/Ca exchanger current was measured in rat myocytes exposed to ramp pulses in Tyrode's solution containing ouabain, nifedipine, and +/-Ni (5 mmol/l). Myocytes were loaded with the fluorescent Ca(2+) indicator Fura-2/AM to estimate intracellular Ca(2+) concentration. SO(2) derivatives significantly inhibited both outward and inward Ni-sensitive Na/Ca exchanger currents without a shift in the reversal potential. The intracellular free [Ca(2+)] was raised by SO(2) derivatives in several concentrations. SO(2) derivatives increased [Ca(2+)](i) in rat myocytes and its mechanism might involve SO(2) derivatives significantly inhibiting Na/Ca exchanger current and enhancing L-type calcium channel.

Runs of ventricular and supraventricular tachycardia triggered by air pollution in patients with coronary heart disease

OBJECTIVE

The authors conducted an investigation of the association between air pollution and arrhythmia.

METHODS

A prospective panel study (October 2000-April 2001) was conducted in Erfurt, Germany. Fifty-seven men with coronary heart disease were subjected to six 24-hour electrocardiogram recordings. Runs of supraventricular and ventricular tachycardia were associated with continuous ultrafine particle counts (UFP), accumulation mode particle counts (ACP), PM2.5, and gaseous pollutants. Poisson and linear regression models were applied adjusting for trend, weekday, and meteorologic data.

RESULTS

Elevated concentrations of UFP, ACP, PM2.5, and nitrogen dioxide increased the risk for supraventricular runs and the number of ventricular runs at almost all lags. Statistically significant associations were found predominantly in the previous 24 to 71 hours and with the 5-day moving average.

CONCLUSION

Elevated concentrations of fine and ultrafine particle increased the risk of arrhythmia in men with coronary heart disease.

Long-term exposure to urban air pollution and myocardial infarction

BACKGROUND

Cohort studies have reported increased risks of cardiopulmonary mortality from long-term air pollution exposure, but the evidence is limited and inconclusive. We studied the association between long-term exposure to source-specific air pollution and myocardial infarction (MI) in a case-control study of first-time MI cases and population controls age 45 to 70 years in Stockholm county in 1992 to 1994.

METHODS

Home addresses during several decades were combined with historical emission databases and dispersion models to obtain annual mean levels of pollutants from traffic and heating during 30 years for 1397 cases and 1870 controls. Nitrogen dioxide (NO2), carbon monoxide (CO), and particulate matter with an aerodynamic diameter less than 10 microm (PM10) were used as indicators of traffic emissions and sulfur dioxide (SO2) as an indicator of emissions from residential heating.

RESULTS

There was no association between long-term average air pollution exposure and overall MI, but an increased risk of fatal MI was suggested, especially for out-of-hospital death. After adjustment for cardiovascular risk factors, the odds ratio for fatal MI associated with a 5th to 95th percentile difference in 30-year average exposure was 1.51 (95% confidence interval = 0.96-2.16) for NO2, 1.22 (0.98-1.52) for CO, 1.39 (0.94-2.07) for PM10, and 1.24 (0.77-2.02) for SO2. For out-of-hospital death, the odds ratio related to NO2 exposure was 2.17 (1.05-4.51).

CONCLUSIONS

This study provides some support for an association between long-term air pollution exposure and fatal cardiovascular disease.

Association of ventricular arrhythmias detected by implantable cardioverter defibrillator and ambient air pollutants in the St Louis, Missouri metropolitan area

BACKGROUND

It has previously been reported that the risk of ventricular arrhythmias is positively associated with ambient air pollution among patients with implantable cardioverter defibrillators (ICD) in Boston.

AIMS

To assess the association of community exposures to air pollution with ventricular arrhythmias in a cohort of ICD patients in metropolitan St Louis, Missouri.

METHODS

ICD detected episodes reported during clinical follow up were abstracted and reviewed by an electrophysiologist to identify ventricular arrhythmias. A total of 139 ventricular arrhythmias were identified among 56 patients. A case-crossover design was used with control periods matched on weekday and hour of the day within the same calendar month. Conditional logistic regression models were adjusted for temperature, barometric pressure, and relative humidity in the 24 hours preceding the event.

RESULTS

There was a significant (24%, 95% CI 7% to 44%) increase in risk of ventricular arrhythmias associated with each 5 ppb increase in mean sulphur dioxide and non-significantly increased risk (22%, 95% CI -6% to 60%; and 18%, 95% CI -7% to 50%) associated with increases in nitrogen dioxide (6 ppb) and elemental carbon (0.5 microg/m3), respectively in the 24 hours before the arrhythmia.

CONCLUSIONS

These results provide evidence of an association between ventricular arrhythmias and ambient air pollutants in St Louis. This is consistent with previous results from Boston, although the pollutants responsible for the increased risk are different.

Air pollution and the heart : cardiovascular effects and mechanisms

There has been increasing awareness in recent years of the adverse cardiovascular effects of ambient air pollution. The recent publication of a statement from the Expert Panel on Population and Prevention Science of the American Heart Association has highlighted this issue. It has been appreciated for several decades that major pollution episodes, such as that associated with the London Fog of 1952, are responsible for increased numbers of deaths and most of these are due to cardiorespiratory causes. Realisation of this prompted government and environmental health initiatives to reduce emissions through establishing air quality standards. Previously, the major sources of air pollution were related to domestic coal burning and industry. However, the pattern of emissions in modern developed countries has changed, resulting in a pollution mixture of different composition to that on which early air quality standards were based. Even current 'lower' levels of air pollution have been shown consistently to be associated with adverse health effects. Over the past two decades, a wealth of epidemiological studies have considered both long- and short-term health effects of air pollution. Although the relative risk of respiratory disease in relation to air pollution exposure seems to be higher than that of cardiovascular disease, the latter are of greater absolute significance in population terms. A number of hypotheses have been proposed in order to explain the observed associations, and recent research efforts have focused on examining the mechanisms underlying the effects. It is suggested that certain subgroups of the population such as the elderly or those with pre-existing cardiorespiratory disease may be more susceptible to the effects of air pollution, and analysis of survival data from cohort studies supports this observation.

Study of the interaction of sulfur dioxide derivative with cardiac sodium channel

The effects of sulfur dioxide (SO(2)) derivatives (bisulfite and sulfite, 1:3 M/M) on voltage-dependent sodium channel in isolated rat ventricular myocyte were studied using the whole cell patch-clamp technique. SO(2) derivatives increased sodium current (I(Na)) in a concentration-dependent manner. SO(2) derivatives at 10 microM significantly shifted steady-state inactivation curve of I(Na) to more positive potentials, but did not affect the activation curve. SO(2) derivatives markedly shifted the curve of time-dependent recovery of I(Na) from inactivation to the left, and accelerated the recovery of I(Na). SO(2) derivatives also significantly shortened the activation and inactivation time constants of I(Na). These results indicated that SO(2) derivatives produced concentration-dependent stimulation of cardiac sodium channels, which due mainly to the interaction of the drug with sodium channels in the inactivated state.

Sulfur dioxide derivative modulation of potassium channels in rat ventricular myocytes

The effects of sulfur dioxide (SO2) derivatives (bisulfite and sulfite, 1:3 M/M) on voltage-dependent potassium current in isolated adult rat ventricular myocyte were investigated using the whole cell patch-clamp technique. SO2 derivatives (10 microM) increased transient outward potassium current (I(to)) and inward rectifier potassium current (I(K1)), but did not affect the steady-state outward potassium current (I(ss)). SO2 derivatives significantly shifted the steady-state activation curve of I(to) toward the more negative potential at the V(h) point, but shifted the inactivation curve to more positive potential. SO2 derivatives markedly shifted the curve of time-dependent recovery of I(to) from the steady-state inactivation to the left, and accelerated the recovery of I(to) from inactivation. In addition, SO2 derivatives also significantly change the inactivation time constants of I(to) with increasing fast time constant and decreasing slow time constant. These results indicated a possible correlation between the change of properties of potassium channel and SO2 inhalation toxicity, which might cause cardiac myocyte injury through increasing extracellular potassium via voltage-gated potassium channels.

Association of short-term ambient air pollution concentrations and ventricular arrhythmias

The authors evaluated the association between ventricular arrhythmias detected by implantable cardioverter defibrillators and ambient air pollution concentrations in the hours immediately before the arrhythmia. Patients given implantable cardioverter defibrillators at the New England Medical Center in Boston, Massachusetts, between mid-1995 and 1999 who lived within 40 km of a central monitoring site (n = 203) were followed until July 2002. The authors used a case-crossover design to study the association between ambient air pollution and up to 798 confirmed ventricular arrhythmias among 84 subjects. The authors found that interquartile range increases in 24-hour moving average particulate matter less than 2.5 mum in aerodynamic diameter and ozone were associated with 19% and 21% increased risks of ventricular arrhythmia, respectively. For each, there was evidence of a linear exposure response, and the associations appeared independent. These associations were stronger than associations with mean concentrations on the same calendar day and previous calendar days. The authors did not find associations with pollutant concentrations less than 24 hours before the arrhythmia. Cases with a prior ventricular arrhythmia within 72 hours had greater risk associated with air pollutants than did cases without a recent arrhythmia. These results confirm previous findings and suggest that matching of pollution periods to arrhythmias is important in detecting such associations.

Association of air pollution with increased incidence of ventricular tachyarrhythmias recorded by implanted cardioverter defibrillators

Epidemiologic studies have demonstrated a consistent link between sudden cardiac deaths and particulate air pollution. We used implanted cardioverter defibrillator (ICD) records of ventricular tachyarrhythmias to assess the role of air pollution as a trigger of these potentially life-threatening events. The study cohort consisted of 203 cardiac patients with ICD devices in the Boston metropolitan area who were followed for an average of 3.1 years between 1995 and 2002. Fine particle mass and gaseous air pollution plus temperature and relative humidity were measured on almost all days, and black carbon, sulfate, and particle number on a subset of days. Date, time, and intracardiac electrograms of ICD-detected arrhythmias were downloaded at the patients' regular follow-up visits (about every 3 months). Ventricular tachyarrhythmias were identified by electrophysiologist review. Risk of ventricular arrhythmias associated with air pollution was estimated with logistic regression, adjusting for season, temperature, relative humidity, day of the week, patient, and a recent prior arrhythmia. We found increased risks of ventricular arrhythmias associated with 2-day mean exposure for all air pollutants considered, although these associations were not statistically significant. We found statistically significant associations between air pollution and ventricular arrhythmias for episodes within 3 days of a previous arrhythmia. The associations of ventricular tachyarrhythmias with fine particle mass, carbon monoxide, nitrogen dioxide, and black carbon suggest a link with motor vehicle pollutants. The associations with sulfate suggest a link with stationary fossil fuel combustion sources.