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

Association between Sleep Quality and Cardiac Autonomic Modulation in Adolescents: A Cross Sectional Study

Objective  To analyze the impact of sleep quality/duration on cardiac autonomic modulation on physically active adolescents with obesity. Materials and Methods  The present cross-sectional study included 1,150 boys with a mean age of 16.6 ± 1.2 years. The assessment of cardiac functions included the frequency domain of heart rate variability (HRV; low frequency - LF; high frequency - HF; and the ratio between these bands -LF/HF -, defined as the sympathovagal balance), and each parameter was categorized as low / high . Physical activity levels and sleep quality/duration were obtained by questionnaires. Abdominal obesity was assessed and defined as waist circumference > 80 th percentile. Results  Poor sleep quality resulted in lower HF (odds ratio [OR]: 1.8; 95% confidence interval [95%CI]: 1.01-3.21]) regardless of physical activity and abdominal obesity. Moreover, the study found no association between sleep duration and HRV parameters in adolescents. Conclusion  Sleep quality, not sleep duration, reduces parasympathetic cardiac modulation apart from other factors such as physical activity and abdominal obesity in adolescents.

Advances in biofeedback and neurofeedback studies on smoking

Smoking is a leading cause of morbidity and premature death constituting a global health challenge. Although, pharmacological and behavioral approaches comprise the mainstay of smoking cessation interventions, the efficacy and safety of pharmacotherapy is not demonstrated for some populations. Non-pharmacological approaches, such as biofeedback (BF) and neurofeedback (NF) could facilitate self-regulation of predisposing factors of relapse such as craving and stress. The current review aims to aggregate the existing evidence regarding the effects of BF and NF training on smokers. Relevant studies were identified through searching in Scopus, PubMed and Cochrane Library, and through hand-searching the references of screened articles. Peer-reviewed controlled and uncontrolled studies, where BF and/or NF training was administered, were included and evaluated according to PICOS framework. Narrative qualitative synthesis of ten eligible studies was performed, aggregated into three categories according to training provided. BF outcomes seem to be affected by smoking behavior prior to training; individualized EEG NF training holds promise for modulating craving-related response while minimizing the required number of sessions. Real-time fMRI NF studies concluded that nicotine-dependent individuals could modulate craving-related brain responses, while mixed results were revealed regarding smokers' ability to modulate brain responses related to resistance towards the urge to smoke. BF and NF training seem to facilitate modulation of autonomous and/or central nervous system activity while also transferring this learned self-regulation to behavioral outcomes. BF and NF training should a) address remaining issues on specificity and scientific validity, b) target diverse demographics, and c) produce robust reproducible methodologies and clinical guidelines for relevant health care providers, in order to be considered as viable complementary tools to standard smoking cessation care.

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.

Linear Short-Term Heart Rate Variability Parameters of Subjects Tobacco Cigarette Smokers and Subjects Nonsmokers in Preoperative Period

Background:

Variations of heart cycles reflect complex dynamic cardiocirculatory regulatory systems in humans. Exposure to tobacco from cigarettes has been shown to elicit specific alterations of heart rate variability parameters leading to predominance of sympathetic and decreasing parameters of parasympathetic measures of cardiac autonomic nervous system tone.

Aim:

The aim of the trial was assessing differences of linear parameters of heart rate variability in subjects with habit of consuming of cigarettes tobacco in regard to subjects who are not consumers of tobacco.

Methods:

Patients of ASA II class with border-line arterial hypertension planned for elective abdominal surgery were included in the clinical trial. Twenty-two subjects were allocated to group I, with history of smoking twenty or more cigarettes per day for five or more years, and twenty-three subjects nonsmokers were allocated to group II. Recordings of electrocardiogram were done by Holter device and later on short- term heart rate variability (five minutes periods) were analyzed. Parameters of time domain analysis (SDNN-standard deviation of NN intervals, mean RR interval, mean heart rate) and frequency domain measures (low frequency (LF), high frequency (HF), and LF/HF ratio) were analyzed.

Results:

Baseline measures of mean NN intervals and standard deviation of normal to normal interval (SDNN) were slightly lower in subjects consumers of nicotine by cigarette tobacco smoking in regard to nonsmokers but without significant difference (640+-15ms vs 675+-8ms, p<0.1;45,1+-3,4 ms vs 51,4+ 3,7ms, p<0.08, respectively). Values of frequency domain measures (LF, HF and LF/HF ratio) have shown variations between two groups, but no significant difference was found.