Heart Rate Variability In People Research Articles

P86: Effect of Virtual Reality on Stress Reduction and Change of Physiological Parameters Including Heart Rate Variability in People With High Stress: An Open Randomized Crossover Trial

Introduction:Although, attempts to apply virtual reality (VR) in mental healthcare are rapidly increasing, it is still unclear whether VR relaxation can reduce stress more than conventional biofeedback.Methods:Participants consisted of 83 healthy adult volunteers with high stress, which was defined as a score of 20 or more on the Perceived Stress Scale-10 (PSS-10). This study used an open, randomized, crossover design with baseline, stress, and relaxation phases. During the stress phase, participants experienced an intentionally generated shaking VR and serial-7 subtraction. For the relaxation phase, participants underwent a randomly assigned relaxation session on day 1 among VR relaxation and biofeedack, and the other type of relaxation session was applied on day 2. We compared the StateTrait Anxiety Inventory-X1 (STAI-X1), STAI-X2, the Numeric Rating Scale (NRS), and physiological parameters including heart rate variability (HRV) indexes in the stress and relaxation phases.Results:A total of 74 participants were included in the analyses. The median age of participants was 39 years, STAI-X1 was 47.27 (SD = 9.92), and NRS was 55.51 (SD = 24.48) at baseline. VR and biofeedback significantly decreased STAI-X1 and NRS from the stress phase to the relaxation phase, while the difference of effect between VR and biofeedback was not significant. However, there was a significant difference in electromyography, LF/HF ratio, LF total, and NN50 between VR relaxation and biofeedbackConclusion:VR relaxation was effective in reducing subjectively reported stress in individuals with high stress.

Brief Report: Changes in Nocturnal Heart Rate Variability in People Living With HIV During the First Year of Antiretroviral Therapy Compared With HIV-Uninfected Community Controls.

Higher nocturnal heart rate and lower nocturnal heart rate variability (HRV) is associated with increased cardiovascular disease mortality. Longitudinal studies on nocturnal HRV in people living with HIV (PLWH) are lacking. We conducted a 1-year prospective cohort study of adult PLWH and HIV-uninfected community controls in northwestern Tanzania. At enrollment, we collected data on cardiovascular risk factors and tested blood samples for hemoglobin, insulin, CD4 cell count, and C-reactive protein. We measured nocturnal HRV and heart rate at baseline and first-year follow-up. Mixed effect linear regression was used to determine predictors of lower HRV. Of the 111 enrolled participants (74 PLWH and 37 HIV-uninfected adults), 57.7% were female and the median age was 40 years. Over 1 year of follow-up, the average nocturnal heart rate was 4.5 beats/minute higher in PLWH ( P = 0.006). In the fully adjusted model (with age, sex, nocturnal heart rate, and diabetes), average nocturnal HRV was 10.5 milliseconds lower in PLWH compared with HIV-uninfected adults ( P = 0.03). Unlike with nocturnal heart rate, nocturnal HRV did not improve after 1 year of ART in PLWH or HIV-uninfected adults (fully adjusted change = -2.5 milliseconds, P = 0.45). Lower educational attainment, lesser pancreatic β-cell function, and anemia were associated with higher HRV. Nocturnal parasympathetic nervous system function was persistently lower in PLWH compared with HIV-uninfected adults even after antiretroviral therapy initiation. Improving nocturnal autonomic nervous system function could be a target for cardiovascular disease prevention in PLWH.

Heart rate variability in people with metabolic syndrome

Metabolic syndrome (MS) is characterized by disorders of carbohydrate and fat metabolism, which can lead to the development of cardiac autonomic neuropathy (CAN). Heart rate variability (HRV) analysis is used to assess the state of autonomic regulation. A decrease in HRV indicates unfavourable changes in autonomic regulation and the development of CAN. The purpose of this study was to compare HRV parameters in patients with metabolic syndrome and healthy individuals without signs of MS. We examined 74 patients with metabolic syndrome (mean age 54.4 ± 1.1 years) and 61 healthy subjects (without signs of MS) (mean age 57.0 ± 1.6 years). The results of the study indicate a significant decrease in HRV in people with MS. However, they had significantly lower values of the SDNN index (by 26%), which characterizes the overall power of neurohumoral regulation of heart rate. Differences in the indicators characterizing short-term, vagal influences were especially pronounced: in patients with MS, RMSSD (by 44%) and HF (by 69%) were lower than in controls. The activity of the baroreflex center of the medulla oblongata, assessed by the spectral power of low-frequency waves (LF), was 55% lower in patients with MS compared to controls. There were no significant differences in the mean duration of the R-R interval, the spectral power of very low frequency (VLF) waves, or the ratio of the spectral powers of low and high frequencies (LF/HF, LFn, HFn) in patients with MS compared to controls. No significant shift in the autonomic balance towards sympathicotonia was found in patients with MS. The analysis of variance confirmed the significant effect of the metabolic syndrome factor on HRV. Thus, the data obtained indicate the development of CAN in people with metabolic syndrome, which is an unfavourable prognostic sign. To assess the effect of MS on the rate of ageing, the biological age (BA) of the examined people with MS was calculated. The formula for calculating BA was obtained on a group of people without MS. The method of multiple stepwise regression was used. The ageing rate was calculated as the difference between biological and chronological age (CA). The average BA in the group of people with MS was 63,20 ± 1,81 years, and in the control group – 53.99 ± 1.71 years (p< 0.05). The difference between BA and CA is 8,81 ± 0,94 years in the group of people with MS and -1.01 ± 0.61 in the control group (p< 0.05). From this we can conclude that MS can be a factor accelerating ageing. _________________________________________________________________________________________ Keywords: metabolic syndrome, heart rate variability, biological age

Heart rate variability in people with metabolic syndrome

Metabolic syndrome (MS) is characterized by disorders of carbohydrate and fat metabolism, which can lead to the development of cardiac autonomic neuropathy (CAN). Heart rate variability (HRV) analysis is used to assess the state of autonomic regulation. A decrease in HRV indicates unfavourable changes in autonomic regulation and the development of CAN. The purpose of this study was to compare HRV parameters in patients with metabolic syndrome and healthy individuals without signs of MS. We examined 74 patients with metabolic syndrome (mean age 54.4 ± 1.1 years) and 61 healthy subjects (without signs of MS) (mean age 57.0 ± 1.6 years). The results of the study indicate a significant decrease in HRV in people with MS. However, they had significantly lower values of the SDNN index (by 26%), which characterizes the overall power of neurohumoral regulation of heart rate. Differences in the indicators characterizing short-term, vagal influences were especially pronounced: in patients with MS, RMSSD (by 44%) and HF (by 69%) were lower than in controls. The activity of the baroreflex center of the medulla oblongata, assessed by the spectral power of low-frequency waves (LF), was 55% lower in patients with MS compared to controls. There were no significant differences in the mean duration of the R-R interval, the spectral power of very low frequency (VLF) waves, or the ratio of the spectral powers of low and high frequencies (LF/HF, LFn, HFn) in patients with MS compared to controls. No significant shift in the autonomic balance towards sympathicotonia was found in patients with MS. The analysis of variance confirmed the significant effect of the metabolic syndrome factor on HRV. Thus, the data obtained indicate the development of CAN in people with metabolic syndrome, which is an unfavourable prognostic sign. To assess the effect of MS on the rate of aging, the biological age (BA) of the examined people with MS was calculated. The formula for calculating BA was obtained on a group of people without MS. The method of multiple stepwise regression was used. The aging rate was calculated as the difference between biological and chronological age (CA). The average BA in the group of people with MS was 63,20 ± 1,81 years, in the control group – 53.99 ± 1.71 years (p< 0.05). The difference between BA and CA is 8,81 ± 0,94 years in the group of people with MS and -1.01 ± 0.61 in control group (p< 0.05). From this we can conclude that MS can be a factor accelerating aging. _________________________________________________________________________________________ Keywords: metabolic syndrome, heart rate variability, biological age

EEG spectral properties and associated ECG-based heart-rate variability in people with insomnia versus healthy sleepers

EEG spectral properties and associated ECG-based heart-rate variability in people with insomnia versus healthy sleepers

Effect of Virtual Reality on Stress Reduction and Change of Physiological Parameters Including Heart Rate Variability in People With High Stress: An Open Randomized Crossover Trial.

Introduction: Although, attempts to apply virtual reality (VR) in mental healthcare are rapidly increasing, it is still unclear whether VR relaxation can reduce stress more than conventional biofeedback.Methods: Participants consisted of 83 healthy adult volunteers with high stress, which was defined as a score of 20 or more on the Perceived Stress Scale-10 (PSS-10). This study used an open, randomized, crossover design with baseline, stress, and relaxation phases. During the stress phase, participants experienced an intentionally generated shaking VR and serial-7 subtraction. For the relaxation phase, participants underwent a randomly assigned relaxation session on day 1 among VR relaxation and biofeedack, and the other type of relaxation session was applied on day 2. We compared the State-Trait Anxiety Inventory-X1 (STAI-X1), STAI-X2, the Numeric Rating Scale (NRS), and physiological parameters including heart rate variability (HRV) indexes in the stress and relaxation phases.Results: A total of 74 participants were included in the analyses. The median age of participants was 39 years, STAI-X1 was 47.27 (SD = 9.92), and NRS was 55.51 (SD = 24.48) at baseline. VR and biofeedback significantly decreased STAI-X1 and NRS from the stress phase to the relaxation phase, while the difference of effect between VR and biofeedback was not significant. However, there was a significant difference in electromyography, LF/HF ratio, LF total, and NN50 between VR relaxation and biofeedback.Conclusion: VR relaxation was effective in reducing subjectively reported stress in individuals with high stress.

Effect of Hypoglycemia on Heart Rate Variability in People with Type 1 Diabetes and Impaired Awareness of Hypoglycemia.

Background:People with impaired awareness of hypoglycemia (IAH) are at elevated risk of severe, potentially hazardous, hypoglycemia and would benefit from a device alerting to hypoglycemia. Heart rate variability (HRV) changes with hypoglycemia due to sympathetic activity. Since IAH is associated with suppressed sympathetic activity, we investigated whether hypoglycemia elicits a measurable change in HRV in patients with T1D and IAH.Method:Eligible participants underwent a modified hyperinsulinemic euglycemic hypoglycemic clamp (glucose nadir, 43.1 ± 0.90 mg/dl), while HRV was measured by a VitalConnect HealthPatch. Measurements of HRV included Root Mean Square of the Successive Differences (RMSSD) and low to high frequency (LF:HF) ratio. Wilcoxon rank-sum test was used for testing within-subject HRV changes.Results:We included 12 participants (8 female, mean age 57 ± 12 years, mean HbA1c 57 ± 5 mmol/mol (7.4 ± 0.4%)). Symptoms increased from 4.0 (1.5-7.0) at euglycemia to 7.5 (5.0-11.0) during hypoglycemia (P = .003). In response to hypoglycemia, the LF:HF ratio and RMSSD increased when normalized for data obtained during euglycemia (both P < .01). The LF:HF ratio increased in 6 participants (50%) and declined in one other participant (8%). The RMSSD decreased in 3 (25%) and increased in 4 (33%) participants. In 2 patients, no change in HRV could be detected in response to hypoglycemia.Conclusions:This study reveals that hypoglycemia-induced changes in HRV are retained in the majority of people with T1D and IAH, and that these changes can be detected by a wearable device. Real-time HRV seems usable for detection of hypoglycemia in patients with IAH.

Noninvasive assessment of autonomic modulation of heart rate variability in the Ts65Dn mouse model of Down syndrome: A proof of principle study.

IntroductionThe Ts65Dn mouse is the most widely used animal model of Down syndrome (DS). Differences in autonomic regulation of heart rate variability (HRV) in individuals with DS have been hypothesized. Pharmacological studies in animal models may help us understand mechanisms underlying observed changes in HRV in people with DS.ObjectiveTo investigate the use a new, noninvasive technique to assess cardiac autonomic modulation in Ts65Dn mice under the effect of adrenergic and cholinergic agonists.MethodWe recorded electrocardiograms (ECGs) from 12 Ts65Dn and 12 euploid control mice. A 30‐min baseline recording was followed by the injection of an adrenergic (isoproterenol [Iso]) or cholinergic (carbachol [CCh]) agonist. Heart rate and HRV were analyzed using a series of methods customized for mice.Results and DiscussionThe ECG apparatus described here allowed us to detect noninvasively long series of heartbeats in freely‐moving animals. During baseline conditions, the yield of detectable heartbeats was 3%–27% of the estimated total number of events, which increased to 35%–70% during the 15‐min period after either Iso or CCh injections. Ts65Dn mice displayed a robust enhanced Iso‐induced negative chronotropic rebound response compared with euploid control mice. We observed a significantly smaller CCh response in Ts65Dn versus control euploid mice in the 6‐ to 10‐min‐interval postcarbachol injection.ConclusionThis work showed that the techniques described here are sufficient for this type of study. However, future studies involving the use of more selective pharmacological agents and/or genetic manipulations will be key to advance a mechanistic understanding of cardiac autonomic regulation in DS.

The Effects of Aerobic Exercise on Heart Rate Variability in People Living with HIV

The Effects of Aerobic Exercise on Heart Rate Variability in People Living with HIV

Reduced heart rate variability in adults with autism spectrum disorder.

A growing body of research has suggested heart rate variability (HRV) may be reduced in autism spectrum disorder (ASD) in comparison to neurotypical cohorts. While there have been several studies investigating HRV in children diagnosed with ASD, few studies have been conducted in adults. The objective of the current study was to investigate autonomic nervous system activity as assessed by HRV in adults diagnosed with ASD. We hypothesized that adults with ASD would show a reduction in HRV compared to neurotypical participants. Participants diagnosed with ASD (n = 55) were recruited from the Autism Clinic for Translational Research at the Brain and Mind Centre (University of Sydney) between 2013 and 2017. Neurotypical participants were recruited from advertisements and online media. Resting state heart rate was measured for 5 min while participants sat in an upright position. Results showed there was an overall significant difference in resting-state HRV between adults diagnosed with ASD compared to the neurotypical control group. Logarithmically transformed high frequency (HF) and root mean square of successive differences were particularly decreased in the ASD group, suggesting lower parasympathetic activity. The use of psychotropic medications and comorbidities were associated with reductions in low frequency of HRV. Our data suggest an overall dysregulation in resting autonomic activity in adults with ASD. This may represent an important physiological mechanism leading to potential cardiovascular risk in ASD, which warrants further investigation. Autism Res 2019, 12: 922-930. © 2019 International Society for Autism Research, Wiley Periodicals, Inc. LAY SUMMARY: ASD is commonly associated with a range of physical and mental health comorbidities. Autonomic disruptions underlying reductions in heart rate variability (HRV) have been linked to a range of mental and physical health conditions. We assessed resting-state HRV in adults diagnosed with ASD in comparison to healthy individuals. Our results showed reduced heart rate variability in people diagnosed with ASD compared to adults without ASD. These findings implicate a role for autonomic activity as a potentially modifiable risk factor for ASD.

Effect of GABA-Fortified Oolong Tea on Reducing Stress in a University Student Cohort

GABA-containing tea has gained popularity as an accessible intervention to reduce the impact of chronic stress-induced autonomic imbalance and increased risk for cardiovascular disease despite a lack of evidence concerning the γ-aminobutyric acid (GABA) content in a cup of the tea and its effects on physiological and psychological stress as measures of cognitive function. We aimed to measure the effects of GABA-fortified tea consumption on heart rate variability (HRV) and stress in 30 participants using a pre-post cohort study design. Ten minute lead II ECG recordings were analyzed with Kubios software. Frequency domain parameters including total power, high and low frequency power, along with heart rate, were determined. A control group that consumed a non-fortified tea was included in the research. Statistical analysis was by two-way ANOVA for two-group comparison with time as an interaction and a significance level of p < 0.05. Oolong tea consumption led to a significant decrease in the immediate stress score and a significant improvement in HRV. We conclude that autonomic imbalance and HRV in people with acute stress is significantly reduced following a cup of GABA fortified oolong tea and highlights the complex interaction between autonomic nervous system function and mood.

Heart rate variability measurement in epilepsy: How can we move from research to clinical practice?

Our objective was to critically evaluate the literature surrounding heart rate variability (HRV) in people with epilepsy and to make recommendations as to how future research could be directed to facilitate and accelerate integration into clinical practice. We reviewed relevant HRV publications including those involving human subjects with seizures. HRV has been studied in patients with epilepsy for more than 30years and, overall, patients with epilepsy display altered interictal HRV, suggesting a shift in autonomic balance toward sympathetic dominance. This derangement appears more severe in those with temporal lobe epilepsy and drug-resistant epilepsy. Normal diurnal variation in HRV is also disturbed in at least some people with epilepsy, but this aspect has received less study. Some therapeutic interventions, including vagus nerve stimulation and antiepileptic medications, may partially normalize altered HRV, but studies in this area are sometimes contradictory. During seizures, the changes in HRV may be complex, but the general trend is toward a further increase in sympathetic overactivity. Research in HRV in people with epilepsy has been limited by inconsistent experimental protocols and studies that are often underpowered. HRV measurement has the potential to aid clinical epilepsy management in several possible ways. HRV may be useful in predicting which patients are likely to benefit from surgical interventions such as vagus nerve stimulation and focal cerebral resection. As well, HRV could eventually have utility as a biomarker of risk for sudden unexpected death in epilepsy (SUDEP). However, at present, the inconsistent measurement protocols used in research are hindering translation into clinical practice. A minimum protocol for HRV evaluation, to be used in all studies involving epilepsy patients, is necessary to eventually allow HRV to become a useful tool for clinicians. We propose a straightforward protocol, involving 5-minute measurements of root mean square of successive differences in wakefulness and light sleep.

The effects of warm water immersion on blood pressure, heart rate and heart rate variability in people with chronic fatigue syndrome.

BackgroundChronic fatigue syndrome (CFS) is a central sensitisation syndrome with abnormalities in autonomic regulation of blood pressure (BP), heart rate (HR) and heart rate variability (HRV). Prior to exploring the effects of hydrotherapy as a treatment for this population, changes in BP, HR and HRV during warm water immersion need to be established.ObjectivesThe study aimed to determine the effects of warm water immersion on BP, HR and HRV in adults with CFS compared to matched-pair healthy adults.MethodA quasi-experimental, single-blinded study design was used with nine CFS participants and nine matched controls. Participants’ BP, HR and HRV were measured before, after 5 minutes and post warm water immersion at the depth of the fourth intercostal space, using the Ithlete® System and Dräger BP monitor.ResultsThere was a significant difference between groups in HRV prior to immersion (control group: 73 [55–74] vs. chronic fatigue syndrome group: 63 [50–70]; p = 0.04). There was no difference in HRV post-immersion. A significant difference in HR after immersion was recorded with the control group having a lower HR than those with CFS (78 [60–86] vs. 86 [65–112]; p = 0.03). The low HRV present in the CFS group prior to immersion suggests autonomic dysregulation. Individuals with CFS may have reduced vagal nerve activation post-immersion. During immersion, HRV of the CFS participants improved similar to that of the healthy controls.ConclusionPrior to immersion, differences were present in the HRV of the participants with CFS compared to healthy controls. These differences were no longer present post-immersion.Clinical implicationsWarm water immersion appears safe and may be beneficial in the management of individuals with CFS.

Heart rate variability as a predictive biomarker of thermal comfort

Thermal comfort is an assessment of one's satisfaction with the surroundings; yet, most mechanisms that are used to provide thermal comfort are based on approaches that preclude physiological, psychological, and personal psychophysics that are precursors to thermal comfort. This leads to many people feeling either cold or hot in an environment that was supposed to be thermally comfortable to most users. To address this problem, this paper proposes to use heart rate variability (HRV) as an alternative indicator of thermal comfort status. Since HRV is linked to homeostasis, we conjectured that people's thermal comfort could be more accurately estimated based on their heart rate variability (HRV). To test our hypothesis, we analyzed statistical, spectral, and nonlinear HRV indices of 17 human subjects doing light office work in a cold, neutral, and hot environment. The resulting HRV indices were used as inputs to machine learning classification algorithms. We observed that HRV is distinctively different depending on the thermal environment and that it is possible to reliably predict each subject's thermal state (cold, neutral, and hot) with up to 93.7% accuracy. The result of this study suggests that it could be possible to design automatic real-time thermal comfort controllers based on people's HRV.

Effects of High-Dose α-Lipoic Acid on Heart Rate Variability of Type 2 Diabetes Mellitus Patients with Cardiac Autonomic Neuropathy in Korea.

BackgroundDiabetic cardiac autonomic neuropathy (CAN) is one of the important complications of diabetes. It is characterized by reduced heart rate variability (HRV).MethodsIn this randomized, double-blind, placebo-controlled, multicenter trial, 75 patients were randomly assigned to one of two groups. One group (n=41) received α-lipoic acid (ALA) at an oral dose of 600 mg/day for the first 12 weeks and then 1,200 mg/day for the next 12 weeks. The other group (n=34) received placebo treatment for 24 weeks. CAN was assessed by measuring HRVs in people with diabetes.ResultsMost of the baseline measures for HRVs were similar between the ALA and placebo groups. Although there were no statistically significant HRV changes in the ALA group compared to the placebo group after 24 weeks of trial, we found a positive tendency in some of the HRV parameters of the ALA group. The standard deviations of normal-to-normal RR intervals in the standing position increased by 1.87 ms in the ALA group but decreased by −3.97 ms in the placebo group (P=0.06). The power spectrum of the low frequency (LF) band in the standing position increased by 15.77 ms2 in the ALA group, whereas it declined by −15.04 ms2 in the placebo group (P=0.08). The high frequency/LF ratio in the upright position increased by 0.35 in the ALA group, whereas it declined by −0.42 in the placebo group (P=0.06). There were no differences between the two groups regarding rates of adverse events.ConclusionAlthough a slight improvement tendency was seen in HRV in the ALA group, there were no statistically significant HRV changes in the ALA group compared to the placebo group after 24 weeks of trial. However, the high oral dose of ALA was well-tolerated.

Meta-analytic evidence for decreased heart rate variability in chronic pain implicating parasympathetic nervous system dysregulation.

Both sympathetic and parasympathetic nervous systems are involved in regulating pain states. The activity of these systems seems to become disturbed in states of chronic pain. This disruption in autonomic balance can be measured through the assessment of heart rate variability (HRV), that is, the variability of the interval between consecutive heart beats. However, there is yet to be a systematic evaluation of the body of literature concerning HRV across several chronic pain conditions. Moreover, modern meta-analytical techniques have never been used to validate and consolidate the extent to which HRV may be decreased in chronic pain. Following the preferred reporting items for systematic reviews and meta-analyses (PRISMA) statement guidelines, this study systematically evaluated and critically appraised the literature concerning HRV in people living with chronic pain. After screening 17,350 sources, 51 studies evaluating HRV in a chronic pain group met the inclusion criteria. Twenty-six moderate-high quality studies were included in quantitative meta-analyses. On average, the quality of studies was moderate. There were 6 frequency-domain and time-domain measures of HRV across a broad range of chronic pain conditions. High heterogeneity aside, pooled results from the meta-analyses reflected a consistent, moderate-to-large effect of decreased high-frequency HRV in chronic pain, implicating a decrease in parasympathetic activation. These effects were heavily influenced by fibromyalgia studies. Future research would benefit from wider use of standardised definitions of measurement, and also investigating the synergistic changes in pain state and HRV throughout the development and implementation of mechanism-based treatments for chronic pain.

Alteration of Heart Rate Variability in People With Bowel Preparation Before Colonoscopy.

In current health examination setting, people frequently undergo heart rate variability (HRV) analysis and colonoscopy on the same day. However, it remains unclear whether the bowel preparation before colonoscopy affects HRV. This study aimed to evaluate the association between HRV and bowel preparation.We conducted a cross-sectional observational study of 1755 people from January 2012 to December 2013 in Taipei, Taiwan. The participants, aged 45 to 65 years, received health examinations that included a physical examination, blood tests, and an HRV analysis. Among these people, 1099 additionally received a colonoscopy on the same day and underwent bowel preparation 1 day before the colonoscopy. The association between HRV and bowel preparation was derived by a multivariable linear regression with adjusted confounding factors.Bowel preparation was associated with a lower standard deviation of the normal-to-normal intervals (SDNN), the root mean square of the successive differences (RMSSD), low-frequency power (LF), and high-frequency power (HF) (all P < 0.0001). After adjusting confounding factors, bowel preparation remained correlated with lower SDNN, RMSSD, LF, and HF (all P < 0.0001). Higher serum phosphorus and lower serum potassium levels were noted in the bowel preparation group (P < 0.0001), and an association between lower HRV and higher serum phosphorus and lower serum potassium levels was only noted in the bowel preparation group.Bowel preparation was significantly associated with lower HRV. The underlying mechanism may be related to an electrolyte imbalance. Cautions may be needed when interpreting HRV reports for people receiving bowel preparations before colonoscopy.

Assessing complexity of heart rate variability in people with spinal cord injury using local scale exponents.

Detrended fluctuation analysis (DFA) has been widely used to study dynamics of heart rate variability (HRV), which provides a quantitative parameter, the scaling exponent a, to represent the correlation properties of RR interval series. However, it has been demonstrated that HRV exhibits complex behavior that cannot be fully described by a single exponent. This study aimed to investigate whether local scale exponent α(t) with t being the time scale can reveal new features of HRV that cannot be reflected by DFA coefficients. To accurately estimate α(t), we developed an approach for correcting a(t) at small scales and verified the approach using simulated signals. We studied HRV in 12 subjects with spinal cord injury and 14 able-bodied controls during sitting and prone postures. The results showed that α(t) provides complementary views of HRV, suggesting that it may be used to evaluate the effects of SCI-induced autonomic damage on HRV.

Unobtrusive monitoring of ECG-derived features during daily smartphone use.

Heart rate variability (HRV) is known to be one of the representative ECG-derived features that are useful for diverse pervasive healthcare applications. The advancement in daily physiological monitoring technology is enabling monitoring of HRV in people's everyday lives. In this study, we evaluate the feasibility of measuring ECG-derived features such as HRV, only using the smartphone-integrated ECG sensors system named Sinabro. We conducted the evaluation with 13 subjects in five predetermined smartphone use cases. The result shows the potential that the smartphone-based sensing system can support daily monitoring of ECG-derived features; The average errors of HRV over all participants ranged from 1.65% to 5.83% (SD: 2.54~10.87) for five use cases. Also, all of individual HRV parameters showed less than 5% of average errors for the three reliable cases.

Inhalation of ultrafine carbon particles alters heart rate and heart rate variability in people with type 2 diabetes.

BackgroundDiabetes may confer an increased risk for the cardiovascular health effects of particulate air pollution, but few human clinical studies of air pollution have included people with diabetes. Ultrafine particles (UFP, ≤100 nm in diameter) have been hypothesized to be an important component of particulate air pollution with regard to cardiovascular health effects.Methods17 never-smoker subjects 30–60 years of age, with stable type 2 diabetes but otherwise healthy, inhaled either filtered air (0–10 particles/cm3) or elemental carbon UFP (~107 particles/cm3, ~50 ug/m3, count median diameter 32 nm) by mouthpiece, for 2 hours at rest, in a double-blind, randomized, crossover study design. A digital 12-lead electrocardiogram (ECG) was recorded continuously for 48 hours, beginning 1 hour prior to exposure.ResultsAnalysis of 5-minute segments of the ECG during quiet rest showed reduced high-frequency heart rate variability with UFP relative to air exposure (p = 0.014), paralleled by non-significant reductions in time-domain heart rate variability parameters. In the analysis of longer durations of the ECG, we found that UFP exposure increased the heart rate relative to air exposure. During the 21- to 45-hour interval after exposure, the average heart rate increased approximately 8 beats per minute with UFP, compared to 5 beats per minute with air (p = 0.045). There were no UFP effects on cardiac rhythm or repolarization.ConclusionsInhalation of elemental carbon ultrafine particles alters heart rate and heart rate variability in people with type 2 diabetes. Our findings suggest that effects may occur and persist hours after a single 2-hour exposure.