Effects of cigarette smoking on heart rate variability and plasma N-terminal pro-B-type natriuretic peptide in healthy subjects: is there the relationship between both markers?

Immunological Insights into Cigarette Smoking-Induced Cardiovascular Disease Risk

Smoking is one of the most prominent addictions of the modern world, and one of the leading preventable causes of death worldwide. Although the number of tobacco smokers is believed to be at a historic low, electronic cigarette use has been on a dramatic rise over the past decades. Used as a replacement for cigarette smoking, electronic cigarettes were thought to reduce the negative effects of burning tobacco. Nonetheless, the delivery of nicotine by electronic cigarettes, the most prominent component of cigarette smoke (CS) is still delivering the same negative outcomes, albeit to a lesser extent than CS. Smoking has been shown to affect both the structural and functional aspects of major organs, including the lungs and vasculature. Although the deleterious effects of smoking on these organs individually is well-known, it is likely that the adverse effects of smoking on these organs will have long-lasting effects on the cardiovascular system. In addition, smoking has been shown to play an independent role in the homeostasis of the immune system, leading to major sequela. Both the adaptive and the innate immune system have been explored regarding CS and have been demonstrated to be altered in a way that promotes inflammatory signals, leading to an increase in autoimmune diseases, inflammatory diseases, and cancer. Although the mechanism of action of CS has not been fully understood, disease pathways have been explored in both branches of the immune system. The pathophysiologically altered immune system during smoking and its correlation with cardiovascular diseases is not fully understood. Here we highlight some of the important pathological mechanisms that involve cigarette smoking and its many components on cardiovascular disease and the immune systems in order to have a better understanding of the mechanisms at play.

Effects of Occupational Stress and Health Behaviors on Heart Rate Variability in Live-Fire Instructors

OBJECTIVES

This study aimed to identify the association between the healthrelated characteristics and the subscales of occupational stress of live fire instructors and heart rate variability (HRV).

METHODS

We conducted questionnaire survey on a general health checkup for 15 live fire instructors. Occupational stress and HRV parameters were measured to determine the association between health behavior, including smoking, drinking, exercise, and sleep-related disorders, and occupational stress of live fire instructors and HRV parameters using Spearman's rank correlation coefficient.

RESULTS

Smoking, insomnia, and job insecurity, a subscale of occupational stress measurement, showed negative Spearman rank correlations with HRV.

CONCLUSIONS

Insomnia, smoking, and job insecurity (due to occupational stress) among live fire instructors were associated with decreased HRV.

N-Terminal Pro Brain, N-Terminal Pro Atrial Natriuretic Peptides, and Dynamic Cerebral Autoregulation

Background

Elevated natriuretic peptides (NP) are associated with adverse cerebrovascular conditions including stroke, cerebral small vessel disease, and dementia. However, the mechanisms underlying these associations remain unclear. In this study, we examined the relationship of NT‐proBNP (N‐terminal pro brain NP) and NT‐proANP (N‐terminal pro atrial NP) with cerebrovascular function, measured by cerebral autoregulation.

Methods and Results

We included 154 participants (mean age 56±4 years old) from the CARDIA (Coronary Artery Risk Development in Young Adults) cohort. NT‐proBNP and NT‐proANP were measured in blood samples from the year 25 examination using electrochemiluminescence Immunoassay and enzyme‐linked immunoassay, respectively. Dynamic cerebral autoregulation (dCA) was assessed at the year 30 examination by transcranial Doppler ultrasound, using transfer function analysis (phase and gain) of spontaneous blood pressure and flow velocity oscillations, where lower phase and higher gain reflect less efficient cerebral autoregulation. We used multivariable linear regression models adjusted for demographics, vascular risk factors, and history of kidney and cardiac diseases. Higher NT‐proBNP levels at year 25 were associated with lower phase (β [95% CI]=−5.30 lower degrees of phase [−10.05 to −0.54]) and higher gain (β [95% CI]=0.06 higher cm/s per mm Hg of gain [0.004–0.12]) at year 30. Similarly, higher NT‐proANP levels were associated with lower phase (β [95% CI]=−9.08 lower degrees of phase [−16.46 to −1.70]).

Conclusions

Higher circulating levels of NT‐proBNP and NT‐proANP are associated with less efficient dCA 5 years later. These findings link circulating NP to cerebral autoregulation and may be one mechanism tying NP to adverse cerebrovascular outcomes.

Effects of smoking status, history and intensity on heart rate variability in the general population: The CHRIS study

Background

Heart rate variability (HRV) reflects the autonomous nervous system modulation on heart rate and is associated with several pathologies, including cardiac mortality. While mechanistic studies show that smoking is associated with lower HRV, population-based studies present conflicting results.

Methods

We assessed the mutual effects of active smoking status, cumulative smoking history, and current smoking intensity, on HRV among 4751 adults from the Cooperative Health Research In South Tyrol (CHRIS) study. The HRV metrics standard deviation of normal-to-normal (NN) inter-beat intervals (SDNN), square root of the mean squared differences of consecutive NN intervals (RMSSD), total power (TP), low (LF) and high frequency (HF) power, and their ratio (LF/HF), were derived from 20-minute electrocardiograms. Smoking status, pack-years (PY), and tobacco grams/day from standardized questionnaires were the main exposures. We fitted linear mixed models to account for relatedness, non-linearity, and moderating effects, and including fractional polynomials.

Results

Past smokers had higher HRV levels than never smokers, independently of PY. The association of HRV with current smoking became apparent when accounting for the interaction between smoking status and PY. In current smokers, but not in past smokers, we observed HRV reductions between 2.0% (SDNN) and 4.9% (TP) every 5 PY increase. Furthermore, current smokers were characterized by dose-response reductions of 9.8% (SDNN), 8.9% (RMSSD), 20.1% (TP), 17.7% (LF), and 19.1% (HF), respectively, every 10 grams/day of smoked tobacco, independently of common cardiometabolic conditions and HRV-modifying drugs. The LF/HF ratio was not associated with smoking status, history, or intensity.

Conclusions

Smoking cessation was associated with higher HRV levels. In current smokers, heavier smoking intensity appears gradually detrimental on HRV, corroborating previous evidence. By affecting both the sympathetic and parasympathetic nervous system indexes, but not the LF/HF balance, smoking intensity seems to exert a systemic dysautonomic effect.

Cardiovascular injury induced by tobacco products: assessment of risk factors and biomarkers of harm. A Tobacco Centers of Regulatory Science compilation

Although substantial evidence shows that smoking is positively and robustly associated with cardiovascular disease (CVD), the CVD risk associated with the use of new and emerging tobacco products, such as electronic cigarettes, hookah, and heat-not-burn products, remains unclear. This uncertainty stems from lack of knowledge on how the use of these products affects cardiovascular health. Cardiovascular injury associated with the use of new tobacco products could be evaluated by measuring changes in biomarkers of cardiovascular harm that are sensitive to the use of combustible cigarettes. Such cardiovascular injury could be indexed at several levels. Preclinical changes contributing to the pathogenesis of disease could be monitored by measuring changes in systemic inflammation and oxidative stress, organ-specific dysfunctions could be gauged by measuring endothelial function (flow-mediated dilation), platelet aggregation, and arterial stiffness, and organ-specific injury could be evaluated by measuring endothelial microparticles and platelet-leukocyte aggregates. Classical risk factors, such as blood pressure, circulating lipoproteins, and insulin resistance, provide robust estimates of risk, and subclinical disease progression could be followed by measuring coronary artery Ca2+ and carotid intima-media thickness. Given that several of these biomarkers are well-established predictors of major cardiovascular events, the association of these biomarkers with the use of new and emerging tobacco products could be indicative of both individual and population-level CVD risk associated with the use of these products. Differential effects of tobacco products (conventional vs. new and emerging products) on different indexes of cardiovascular injury could also provide insights into mechanisms by which they induce cardiovascular harm.

The Association of Cigarette Smoking With High-Frequency Heart Rate Variability: An Ecological Momentary Assessment Study

OBJECTIVE

Evidence from both laboratory and observational studies suggests that acute and chronic smoking leads to reduced high-frequency heart rate variability (HF-HRV), a measure of cardiac vagal regulation. We used ecological momentary assessment (EMA) to study the effect of smoking on concurrent HF-HRV in a trial measuring the effects of hostility reduction and compared 24-hour HF-HRV in smokers and nonsmokers.

METHOD

Ambulatory electrocardiogram data were collected before randomization from 149 healthy individuals with high hostility levels (20-45 years, body mass index ≤ 32 kg/m) and paired with concurrent EMA ratings of smoking and physical position during waking hours. A multilevel mixed model was estimated associating ln(HF-HRV) from smoking status (between-person factor) and person-centered momentary smoking (within-person factor, treated as a random effect), adjusting for momentary physical position, medication use, and consumption of alcohol and caffeine.

RESULTS

Thirty-five smokers and 114 nonsmokers provided both EMA and HF-HRV data. Within smokers, ln HF-HRV was reduced by 0.31 millisecond (p = .04) when participants reported having recently smoked cigarettes, compared with when they had not. The 24-hour HF-HRV was significantly lower in smokers (M [SD] = 5.24 [0.14] milliseconds) than nonsmokers (5.63 ± 0.07 milliseconds, p = .01).

CONCLUSIONS

In healthy smokers with high hostility levels used as their own controls during daily living, smoking acutely reduced HF-HRV. HF-HRV was also reduced in smokers as compared with nonsmokers. Although limited by a small sample of individuals with high hostility levels, these findings nonetheless provide additional evidence that cardiac vagal regulation is lowered by cigarette smoking, which may be one of the numerous pathophysiological effects of smoking.

Vagally-mediated heart rate variability and indices of well-being: Results of a nationally representative study

OBJECTIVE

High frequency (HF) heart rate variability (HRV) has long been accepted as an index of cardiac vagal control. Recent studies report relationships between HF-HRV and indices of positive and negative affect, personality traits and well-being but these studies generally are based on small and selective samples.

METHOD

These relationships were examined using data from 967 participants in the second Midlife in the U.S. (MIDUS II) study. Participants completed survey questionnaires on well-being and affect. HF-HRV was measured at rest. A hierarchical series of regression analyses examined relationships between these various indices and HF-HRV before and after adjustment for relevant demographic and biomedical factors.

RESULTS

Significant inverse relationships were found only between indices of negative affect and HF-HRV. Relationships between indices of psychological and hedonic well-being and positive affect failed to reach significance.

CONCLUSIONS

These findings raise questions about relationships between cardiac parasympathetic modulation, emotion regulation, and indices of well-being. (PsycINFO Database Record

Pharmacokinetic-pharmacodynamic modelling of acute N-terminal pro B-type natriuretic peptide after doxorubicin infusion in breast cancer

AIMS

The aim of the present study was to develop a pharmacokinetic-pharmacodynamic (PK-PD) model to characterize the relationship between plasma doxorubicin and N-terminal pro B-type natriuretic peptide (NT-proBNP) concentrations within 48 h of doxorubicin treatment.

METHODS

The study enrolled 17 female patients with stages 1-3 breast cancer and receiving adjuvant doxorubicin (60 mg m(-2) ) and cyclophosphamide (600 mg m(-2) ) every 14 days for four cycles. In two consecutive cycles, plasma concentrations of doxorubicin, doxorubicinol, troponin and NT-proBNP were collected before infusion, and up to 48 h after the end of doxorubicin infusion. Nonlinear mixed-effects modelling was used to describe the PK-PD relationship of doxorubicin and NT-proBNP.

RESULTS

A three-compartment parent drug with a one-compartment metabolite model best described the PK of doxorubicin and doxorubicinol. Troponin concentrations remained similar to baseline. An indirect PD model with transit compartments best described the relationship of doxorubicin exposure and acute NT-proBNP response. Estimated PD parameters were associated with large between-subject variability (total assay variability 38.8-73.9%). Patient clinical factors, including the use of enalapril, were not observed to be significantly associated with doxorubicin PK or NT-proBNP PD variability.

CONCLUSION

The relationship between doxorubicin concentration and the acute NT-proBNP response was successfully described with a population PK-PD model. This model will serve as a valuable framework for future studies to identify clinical factors associated with the acute response to doxorubicin. Future studies are warranted to examine the relationship between this acute response and subsequent heart failure. Should such a relationship be established, this model could provide useful information on patients' susceptibility to doxorubicin-induced long-term cardiotoxicity.

Linking Daily Stress Processes and Laboratory-Based Heart Rate Variability in a National Sample of Midlife and Older Adults

OBJECTIVE

This study evaluates the associations between people's trait-like patterns of stress in daily life (stressor frequency, perceived stressor severity, affective reactivity to stressors, and negative affect) and laboratory-assessed heart rate variability (HRV).

METHODS

Data were collected from 909 participants aged 35 to 85 years in the Midlife in the United States Study. Participants reported negative affect and minor stressful events during telephone interviews on 8 consecutive evenings. On a separate occasion, HRV was measured from electrocardiograph recordings taken at rest during a laboratory-based psychophysiology protocol. Regression models were used to evaluate the associations between daily stress processes and three log-transformed HRV indices: standard deviation of R-R intervals (SDRR), root mean square of successive differences (RMSSD), and high-frequency power (high-frequency HRV [HF-HRV]). Analyses were adjusted for demographics, body mass index, comorbid conditions, medications, physical activity, and smoking.

RESULTS

Stressor frequency was unrelated to HRV (r values ranging from -0.04 to -0.01, p values >.20). However, people with greater perceived stressor severity had lower resting SDRR (fully adjusted B [standard error {SE}] = -0.05 [0.02]), RMSSD (-0.08 [0.03]), and HF-HRV (-0.16 [0.07]). Individuals with more pronounced affective reactivity to stressors also had lower levels of all three HRV indices (SDRR: B [SE] = -0.28 [0.14]; RMSSD: -0.44 [0.19]; HF-HRV: -0.96 [0.37]). Furthermore, aggregated daily negative affect was linked to reduced RMSSD (B [SE] = -0.16 [0.08]) and HF-HRV (-0.35 [0.15]).

CONCLUSIONS

In a national sample, individual differences in daily negative affect and responses to daily stressors were more strongly related to cardiovascular autonomic regulation than the frequency of such stressors.

N-Terminal Pro-B-Type Natriuretic Peptide Levels Inversely Correlated With Heart Rate Variability in Patients With Unstable Angina Pectoris

We explored the relationships between heart rate variability (HRV) and levels of N-terminal Pro-B-type natriuretic peptide (NT-proBNP) in patients with unstable angina pectoris (UA).A total of 90 consecutive patients admitted < 48 hours for UA were included. Serum levels of NT-proBNP were measured from blood samples. The cohort was divided into tertiles according to NT-proBNP levels. HRV parameters including SDNN, RMSSD, LF, HF, TP, and VLF were assessed by 24-hour Holter ECG monitoring.The median (IQR) NT-proBNP level was 177.02 (64.76, 740.70) pg/mL. Patients with SDNN < 100 ms had higher levels of NT-proBNP than those with SDNN > 100 ms (P = 0.003). With increasing levels of NT-proBNP, both the 24hour monitoring HRV and night-monitoring HRV showed that SDNN and VLF gradually decreased (P < 0.01), and patients in the NT-proBNP lowest tertile group had higher LF values than the other two groups (P < 0.05); however, no difference was found in RMSSD, HF, and TP. During the daytime, the LF, VLF, and TP values were lower in the NTproBNP highest group compared with the lowest tertile group (P < 0.05). NT-proBNP levels correlated negatively with SDNN (r = -0.314, P = 0.003) and VLF (r = -0.397, P < 0.001) but not with other HRV parameters. Multiple regression analysis showed that serum levels of NT-proBNP remained predictive of SDNN (β = -0.060, P = 0.001) and VLF (β = -0.145, P < 0.001), even after adjustment for confounders.Our study showed that the elevated serum levels of NT-proBNP predict reduced HRV parameters, and the increased NT-proBNP levels combined with decreased HRV represent the degree of neurohormonal dysfunction and may be better prognostic predictors for risk stratification in UA patients.

COMPARAÇÃO DA MODULAÇÃO AUTONÔMICA CARDÍACA DURANTE ESFORÇO DE FUMANTES E NÃO FUMANTES

Introdução O tabagismo é uma das principais causas de morbimortalidade em todo o mundo. Indivíduos fumantes têm risco aumentado de desenvolver disfunção autonômica, a qual pode ser avaliada tanto pela variabilidade da frequência cardíaca (VFC) como pela frequência cardíaca de recuperação (FCRec). A maioria dos estudos envolvendo esta análise é realizada em adultos de idade avançada e na condição de repouso. Objetivos Comparar a atividade autonômica cardíaca em repouso e esforço, em homens jovens, fumantes e não fumantes. Métodos Trinta e dois jovens voluntários, (idade 22,0 ± 2,8 anos) foram distribuídos em dois grupos: o grupo fumante (GF; n=15) e o não fumante (GNF; n=17). Realizou-se o teste de Cooper, com análise da VFC pelo cardiofrequencímetro Polar(r)s810i, em repouso e durante o esforço e FCRec. Resultados No GF, 73% foram classificados com nível de dependência nicotínica "muito baixa" segundo questionário de Fargeström. A classificação de ativos e muito ativos pelo questionário IPAQ correspondeu a mais de 50% da amostra em ambos os grupos. Não se observou diferenças significativas entre os grupos na VFC, tanto no repouso quanto no esforço. Entretanto, em cada grupo, notou-se diferença na maioria dos índices de VFC do repouso para o esforço. No teste de Cooper não foram observadas diferenças significativas na FCmédia, FCpico e de FCRec entre os grupos, mas notou-se uma melhor capacidade funcional no GNF pela distância caminhada (2050,2 ± 300,0 vs. 1780,3 ± 390,4 m, p=0,036). Conclusão O GF apresentou menor capacidade funcional e ativação parassimpática durante o esforço, além de menores índices de VFC durante repouso, o que pode sugerir um comprometimento precoce na modulação autonômica cardíaca.

Are smoking and passive smoking related with heart rate variability in male adolescents?

Objective

To analyze the relation between smoking and passive smoking with heart rate variability parameters in male adolescents.

Methods

The sample consisted of 1,152 males, aged 14 and 19 years. Data related to smoking and passive smoking were collected using a questionnaire. RR intervals were obtained by a heart rate monitor, on supine position, for 10 minutes. After collecting the RR intervals, time (standard deviation of all RR intervals, root mean square of the squared differences between adjacent normal RR intervals and the percentage of adjacent intervals over 50ms) and frequency domains (low and high frequency and sympathovagal balance) parameters of heart rate variability were obtained.

Results

No significant differences between smoker and nonsmoker adolescents were observed in heart rate variability parameters (p>0.05). Similarly, heart rate variability parameters did not show significant difference between exposed and not exposed to passive smoking (p>0.05).

Conclusion

Cigarette smoking and passive smoking are not related to heart rate variability in adolescence.

Psychosocial correlates of atrial natriuretic peptide: a marker of vascular health

BACKGROUND

Psychosocial factors have been associated with cardiovascular outcomes, but few studies have examined the association between psychosocial function and natriuretic peptides.

PURPOSE

The purpose of this study is to determine the predictive value of hostility, anger, and social support in relation to atrial natriuretic peptide (ANP), a marker of vascular health, among middle-aged men.

METHODS

One hundred twenty-one men (mean age = 39.8 years, SD = 4.1) underwent assessments of ANP and completed the Cook-Medley Hostility Scale, the Spielberger State-Trait Anger Scale, and the Interview Schedule for Social Interaction.

RESULTS

Higher levels of hostility (β = 0.22 [95 % CI 0.04, 0.40], P = 0.032) and trait anger (β = 0.18 [95 % CI 0.01, 0.37], P = 0.044) were associated with greater ANP levels. In contrast, higher perceived social support was also associated with lower ANP levels, (β = -0.19 [95 % CI -0.05, -0.41], P = 0.010).

CONCLUSIONS

Psychosocial factors, including hostility, anger, and social support, are associated with varying ANP levels among middle-aged men, independent of cardiovascular and behavioral risk factors.

Effects of cigarette smoke on Holter ECG recordings in patients with arterial hypertension. Part 2: Parameters of heart rate turbulence

The studies aimed at evaluation of cigarette smoke effect on heart rate turbulence (HRT) in patients with arterial hypertension (AH). 223 consecutive individuals were qualified to the studies. The following groups of patients not suffering from other disease which may affect HRT were distinguished: 1--patients with AH (n=145); 2--patients without AH (n=48). In group 1 the following patient subgroups were studied: A--active smokers (n=42), B--non-smokers exposed to cigarette smoke (n=30), C--non-smokers not exposed to tobacco smoke (n=34), D--former smokers who had quit smoking (n=26). In every participant HRT analysis was conducted. Subgroup A manifested significantly higher values of TO and lower values of TS as compared to analogous values obtained in subgroups B-D. Subgroups B and D were characterized also by significantly higher values of TO and lower values of TS as compared to subgroup C. Active and passive cigarette smoking were found to represent independent risk factors for an abnormal HRT.

CONCLUSION

Both active and passive exposure to tobacco smoke induces causes abnormal HRT in patients with arterial hypertension.

Effects of cigarette smoke on Holter ECG recordings in patients with arterial hypertension. Part 1: Time domain parameters of heart rate variability

This report was intended to evaluate the effect of cigarette smoke on heart rate variability (HRV) in patients with arterial hypertension (AH). 223 individuals were qalified to the studies. The following groups of patients not suffering from other disease which may affect HRV were delineated: 1 - patients with AH (n=145); 2 - patients without AH (n=48). In group 1 the following patient groups were studied: A - active smokers (n=42), B - non-smokers exposed to cigarette smoke (n=30), C - non-smokers not exposed to tobacco smoke (n=34), D - former smokers (n=26). A time domain HRV analysis was carried out. Group 1 versus group 2 manifested significantly lower mean values of most parameters in the HRV time domain analysis. Subgroups A, B and D versus subgroup C also exhibited significantly lower mean values of most parameters in the HRV time domain analysis. Active cigarette smoking and passive exposure to tobacco smoke represented independent risk factors for a decreased HRV.

CONCLUSIONS

Active and passive exposure to cigarette smoke decreases HRV in hypertensive patients.

High N-terminal pro-B-type natriuretic peptide levels are associated with reduced heart rate variability in acute myocardial infarction

Aim

We investigated the relationships between the autonomic nervous system, as assessed by heart rate variability (HRV) and levels of N-terminal Pro-B-type Natriuretic Peptide (Nt-proBNP) in patients with acute myocardial infarction (MI).

Methods and Results

The mean of standard deviation of RR intervals (SDNN), the percentage of RR intervals with >50 ms variation (pNN50), square root of mean squared differences of successive RR intervals (rMSSD), and frequency domain parameters (total power (TP), high frequency and low frequency power ratio (LF/HF)) were assessed by 24 h Holter ECG monitoring. 1018 consecutive patients admitted <24 h for an acute MI were included. Plasma Nt-proBNP (Elecsys, Roche) was measured from blood samples taken on admission. The median (IQR) Nt-proBNP level was 681(159–2432) pmol/L. Patients with the highest quartile of Nt-proBNP were older, with higher rate of risk factors and lower ejection fraction. The highest Nt-proBNP quartile group had the lowest SDNN, LF/HF and total power but similar pNN50 and rMSSD levels. Nt-proBNP levels correlated negatively with SDNN (r = −0.19, p<0.001), LF/HF (r = −0.37, p<0.001), and LF (r = −0.29, p<0.001) but not HF (r = −0.043, p = 0.172). Multiple regression analysis showed that plasma propeptide levels remained predictive of LF/HF (B(SE) = −0.065(0.015), p<0.001)), even after adjustment for confounders.

Conclusions

In conclusion, our population-based study highlights the importance of Nt-proBNP levels to predict decreased HRV after acute MI.

Effects of active and passive tobacco cigarette smoking on heart rate variability

Given the widespread incidence of smoking as well as its deleterious health effects, it is crucial to examine practical and cost effective prognostic markers assessing its health impact. Heart rate variability (HRV) is a straightforward and cost effective technique to foresee health problems of cardiovascular nature and may be used to predict in advance smoking-induced health effects. In this review we evaluate the existing biological evidence regarding the effects of smoking on HRV and their associated cardiovascular consequences. In addition, we summarize fundamental information on the various HRV indicators and their diagnostic significance in relation to heart failure. An in depth analysis of the various HRV indices characterizing changes in the activation of the autonomic nervous system is provided together with a critical evaluation of all evidence published to date on the influence of chronic and acute active and passive smoking on HRV. Overall, the vast majority of published evidence suggests that acute and chronic active and passive smoking generate marked disruptions in the normal autonomic nervous system functioning characterized by increased sympathetic drive and reduced HRV and parasympathetic modulation. The proposed mechanisms that may generate this smoke-induced HRV reduction as well as its clinical implications are thoroughly evaluated.

Effects of posture and acute sleep deprivation on heart rate variability

PURPOSE

In our previous study to investigate autonomic nervous system (ANS) activity due to radio frequency (RF) radiation using heart rate variability (HRV), drowsiness was observed in approximately half of all subjects. Therefore, the usage of HRV with unwanted drowsiness could falsely indicate the effects of RF radiation by mobile phones on the ANS. The objective of this study was to determine which posture is appropriate for accurate HRV analysis for provocation study.

MATERIALS AND METHODS

A total of 52 healthy subjects (25 males and 27 females) participated in this experiment. We measured the number of times a subject showed drowsiness or sleep deprivation due to awakening, and analyzed HRV six times over 30 minutes in sitting and recumbent postures, using power spectrum.

RESULTS

We employed the ratio of low frequency power to high frequency power (LFP/HFP) to analyze the changes in the ANS. The number of sleep deprivation occurrences in the sitting posture was significantly less than that in the recumbent posture (p<0.01), resulting in smaller increase of LFP/HFP. Although LFP/HFP of the two postures varied with time without any provocation, it was more stable in sitting than in recumbent postures.

CONCLUSION

A sitting posture is preferable to a recumbent posture for analyzing HRV, because of decreased drowsiness and sleep deprivation, thereby decreasing variation of LFP/HFP during experiment. Considering the drowsiness, it is also recommended that any experiment should be completed within 15 minutes, if possible.

Analysis of 24-hour heart rate variations in patients with epilepsy receiving antiepileptic drugs

OBJECTIVE

The goal of the study described here was to evaluate interictal heart rate variability (HRV) in young patients with epilepsy, a patient population in whom sudden unexpected death in epilepsy (SUDEP) is known to be more common.

METHODS

Twenty-four-hour ambulatory ECG Holter recordings of 37 patients (15-40 years old) and 32 healthy controls were compared.

RESULTS

All of the time domain indices (SDNN, SDANN, RMSSD, and HRV triangular index) were significantly suppressed (P<0.001), and there was a marked reduction in parasympathetic tone (reduced HF(nu,)P<0.001) and an increase in sympathetic tone (increased LF(nu) and LF/HF ratio, P<0.001) in the patient group. Stepwise linear regression analysis revealed that polytherapy and epilepsy duration >10 years were independent variables associated with a reduction in SDNN.

CONCLUSION

Our data suggest that the major determinants of suppressed SDNN are polytherapy and epilepsy duration >10 years. Analysis of spectral measures of frequency domain indices suggests that an increased sympathetic tone in association with a decreased parasympathetic tone may constitute the mechanism underlying SUDEP in young people with epilepsy.

Influence of heavy cigarette smoking on heart rate variability and heart rate turbulence parameters

BACKGROUND

Cigarette smoking increases the risk of cardiovascular events related with several mechanisms. The most suggested mechanism is increased activity of sympathetic nervous system. Heart rate variability (HRV) and heart rate turbulence (HRT) has been shown to be independent and powerful predictors of mortality in a specific group of cardiac patients. The goal of this study was to assess the effect of heavy cigarette smoking on cardiac autonomic function using HRV and HRT analyses.

METHODS

Heavy cigarette smoking was defined as more than 20 cigarettes smoked per day. Heavy cigarette smokers, 69 subjects and nonsmokers 74 subjects (control group) were enrolled in this study. HRV and HRT analyses [turbulence onset (TO) and turbulence slope (TS)] were assessed from 24-hour Holter recordings.

RESULTS

The values of TO were significantly higher in heavy cigarette smokers than control group (-1.150 +/- 4.007 vs -2.454 +/- 2.796, P = 0.025, respectively), but values of TS were not statistically different between two groups (10.352 +/- 7.670 vs 9.613 +/- 7.245, P = 0.555, respectively). Also, the number of patients who had abnormal TO was significantly higher in heavy cigarette smokers than control group (23 vs 10, P = 0.006). TO was correlated with the number of cigarettes smoked per day (r = 0.235, P = 0.004). While LF and LF/HF ratio were significantly higher, standard deviation of all NN intervals (SDNN), standard deviation of the 5-minute mean RR intervals (SDANN), root mean square of successive differences (RMSSD), and high-frequency (HF) values were significantly lower in heavy smokers. While, there was significant correlation between TO and SDNN, SDANN, RMSSD, LF, and high frequency (HF), only HF was correlated with TS.

CONCLUSION

Heavy cigarette smoking has negative effect on autonomic function. HRT is an appropriate noninvasive method to evaluate the effect of cigarette on autonomic function. Simultaneous abnormal HRT and HRV values may explain increased cardiovascular event risk in heavy cigarette smokers.

Heart rate variability is related to self-reported physical activity in a healthy adolescent population

This study investigated whether there is a relationship between heart rate variability (HRV) versus lifestyle and risk factors for cardiovascular disease in a population of healthy adolescents. HRV is as an index of tonic autonomic activity and in adults HRV is related to lifestyle and risk factors for cardiovascular disease, but it is not known if this is the case in adolescents. HRV was registered for 4 min in sitting position in 99 healthy adolescents (age range 15 years 11 months–17 years 7 months) and repeated after 6 months. On both occasions there were significant correlations (P < 0.05) between physical activity and HRV, with respective r values: high frequency (HF) 0.26, 0.30; low frequency power (LF) 0.35, 0.29 and the standard deviation of inter-beat intervals (SDNN) 0.28, 0.37. There was no significant interaction between first and second measurements. In contrast, there were no correlations to sleeping patterns, eating habits and smoking. Risk factors for cardiovascular disease [body mass index (BMI = weight (kg)/length in m²), systolic blood pressure and p-glucose] did not show any repeatable significant correlations to HRV. Multiple regression models showed that physical activity was a predictor for HF, LF and SDNN in both measurements. In conclusion HF, LF and SDNN were reproducible after 6 months and were related to physical activity on both occasions.

Women with posttraumatic stress disorder have larger decreases in heart rate variability during stress tasks

The relationship between posttraumatic stress disorder (PTSD) and high frequency heart rate variability (HF-HRV) was investigated during a resting baseline period and two 4-minute laboratory speech tasks. Participants were 20 women with PTSD and 20 age- and gender-matched controls. Parasympathetic nervous system (PNS) cardiac control was measured as HF-HRV (0.12-0.40 Hz) using power spectrum analysis. Participants with PTSD had significantly greater reductions in HF-HRV during two speech tasks (trauma recall and mental arithmetic) than control. These results suggest that PTSD is related to the magnitude of decrease in parasympathetic cardiac control during stress in women. Health implications of altered PNS activity associated with PTSD deserve further study.