Autonomic Nerve Function Predicts Risk of Early Death after Discharge in Acute Medical Disease

BACKGROUND

Heart rate variability, a marker of autonomic function, has shown promising prognostic results in specific populations, but has not been tested in a general medical population. We hypothesized that heart rate variability identifies high-risk medical patients early after admission to the hospital.

METHODS

This was a single-center prospective cohort study of acutely admitted medical patients aged ≥18 years with a life expectancy ≥3 months, included between 2019-2023. Unstable patients needing direct admission to the intensive care unit were excluded. Heart rate variability was recorded within 24 hours of admission for 10 minutes. The standard deviation of normal-normal beats (SDNN) was the primary heart rate variability marker. Low SDNN was defined as the lowest tertile (≤22 ms). The primary outcome was 30-day all-cause mortality. The secondary outcome was 30-day readmission or mortality.

RESULTS

Among 721 patients included, low SDNN carried an 8-fold greater risk of 30-day mortality in univariate analysis (hazard ratio [HR] 8.3; P = .001); in multivariate analyses a 4-fold greater risk (HR 3.8; P = .037). Low SDNN was associated with the combined outcome of 30-day mortality or readmission (HR 1.5; P = .03) in multivariate analysis. In receiver operating characteristics analyses, low SDNN improved the predictive accuracy of early warning score for 30-day mortality or readmission from 0.63 to 0.71 (P = .008) but did not improve the accuracy for 30-day mortality alone.

CONCLUSIONS

In patients admitted due to acute medical illness, low heart rate variability predicted 30-day mortality and readmission, suggesting heart rate variability as a tool to identify patients at high and low risk of relevant endpoints.

Effects of slow breathing training on hemodynamic changes, cardiac autonomic function and neuroendocrine response in people with high blood pressure: A randomized control trial

BACKGROUND

High blood pressure (BP) is a non-communicable disease that is a risk factor for cardiovascular disease and is the leading cause of mortality and morbidity worldwide. High BP can be managed by both pharmacological and non-pharmacological interventions. Non-pharmacological treatment, such as slow-breathing training (SBT), has been shown to reduce BP. However, there are few studies on the effect of SBT on both cardiac activation and oxidative stress in people with high BP.

OBJECTIVES

To explore the effect of SBT on cardiac autonomic function (i.e., heart rate variability: HRV) and neuroendocrine response (i.e., salivary cortisol).

METHODS

One hundred people (including 89 women) with high BP were randomly assigned to either a control (n = 50) or intervention group (n = 50). The intervention program was conducted for 30 min per day, for 5 days per week, for 4 weeks, with a total of 20 sessions of the SBT at the rate of 10 times per minute, whereas the control group was required to continue with their daily routine. HRV, BP, and salivary cortisol were measured before and after the intervention program. A two-way mixed ANOVA was performed for within-group and between-group comparisons over time.

RESULTS

Of the 100 participants, 71 individuals completed the study. The participants in the intervention group had a lower BP and salivary cortisol levels compared to those in the control group (p < .05). Further, those participants showed an increase in the standard deviation of normal R-R intervals after the 4-week intervention program (p < .05).

CONCLUSION

This study provided evidence demonstrating the effect of SBT on cardiac autonomic and stress reactivity, which has important implications for health promotion in people with high BP.

CLINICAL TRIAL REGISTRATION NUMBER

TCTR20180302008.

Relationship between dust allergen sensitization and cardiac autonomic function in patients with chronic obstructive pulmonary disease

OBJECTIVE

Cardiac autonomic function predicts cardiovascular disease risk. The aim of this study was to investigate the relationship between sensitization to dust allergens and cardiac autonomic dysfunction in patients with chronic obstructive pulmonary disease (COPD), and to provide new ideas for the prevention of cardiovascular complications in these patients.

METHODS

Immunoassays for sensitization to cats/dogs, cockroaches and dust mites were performed in 840 patients with COPD. Indicators of heart rate variability in these patients were used to assess cardiac autonomic function, including standard deviation of normal-to-normal intervals (SDNN), root-mean square of successive differences between normal-to-normal intervals (RMSSD), low-frequency power (LF), high-frequency power (HF), and LF/HF ratios, which were obtained based on ambulatory electrocardiographic monitoring data. The relationship between sensitization to these dust allergens and heart rate variability was explored using multivariate logistic regression.

FINDINGS

The multivariate analyses showed that sensitization to total allergens was associated with reduced levels of SDNN, RMSSD, LF and HF and with increased levels of the LF/HF ratio in the patients with COPD (p < .05).

CONCLUSION

Dust allergen sensitization may be associated with cardiac autonomic dysfunction in patients with COPD. Whether desensitization can prevent cardiovascular complications in these patients should be further explored.

Effects of high intensity interval-based inspiratory muscle training in patients with heart failure: A single-blind randomized controlled trial

BACKGROUND

Given the promising effects of inspiratory muscle training (IMT), determining the most appropriate IMT protocol will optimize the training benefits.

OBJECTIVES

The objective of this study was to determine the effects of high intensity interval-based inspiratory muscle training (H-IMT) on cardiovascular, pulmonary, physical, and psychosocial functions in patients with heart failure and reduced ejection fraction (HFrEF).

METHODS

Thirty-four patients with HFrEF were randomly assigned to the H-IMT or control group for 3 days/week, 8 weeks training period. The H-IMT group performed IMT at least 70% of the maximal inspiratory pressure, whereas the control group performed unloaded IMT. Each session occurred 7 sets with a total of 21 min consisting of 2-min training and 1-min interval. Heart rate variability (HRV), arterial stiffness, respiratory muscle strength and endurance, diaphragm thickness, quadriceps strength, functional capacity, frailty, dyspnea, fatigue, disease-specific health-related quality of life (HRQoL), and generic HRQoL were evaluated at baseline and after 8 weeks training period by blinded assessors.

RESULTS

Statistically significant between-group differences were observed in the time domain parameters of HRV, arterial stiffness, inspiratory and quadriceps muscle strength, respiratory muscle endurance, diaphragm thickness, functional capacity, frailty, dyspnea, fatigue, and disease-specific HRQoL in favor of the H-IMT group (p<0.05).

CONCLUSIONS

H-IMT is an effective protocol for improving cardiac autonomic function, arterial stiffness, inspiratory and quadriceps muscle strength, respiratory muscle endurance, diaphragm thickness, functional capacity, frailty, dyspnea, fatigue, and disease-specific quality of life in patients with HFrEF.

CLINICAL TRIAL REGISTRATION

NCT04839211.

Greater post-exercise hypotension in healthy young untrained men after exercising in a hot compared to a temperate environment

This research examined the effects of exercising in a hot compared to a temperate environment on post-exercise hemodynamics in untrained men. We hypothesized exercise in a hot compared to a temperate environment would elicit greater post-exercise hypotension, and this would be attributable to higher cutaneous vascular conductance and sweat loss, and lower heart rate variability (HRV) and cardiac baroreflex sensitivity (cBRS). In a randomized counterbalanced order, 12 untrained healthy men completed two trials involving 40-min leg-cycling exercise at either 23 °C (CON) or 35 °C (HOT). Post-exercise participants rested supine for 60 min at 23 °C whilst hemodynamic and thermoregulatory measurements were assessed. Post-exercise hypotension was greater after exercising in a hot than a temperate environment as indicated by a lower mean arterial pressure at 60 min recovery (CON 83 ± 5 mmHg, HOT 78 ± 5 mmHg, Mean difference [95% confidence interval], -5 [-8, -3] mmHg). Throughout recovery, cutaneous vascular conductance was higher, and cBRS and HRV were lower after exercising in a hot than in a temperate environment (P < 0.05). Sweat loss was greater on HOT than on CON (P < 0.001). Post-exercise hypotension after exercising in the hot environment was associated with sweat loss (r = 0.66, P = 0.02), and changes in cutaneous vascular conductance (r = 0.64, P = 0.03), and HRV (Root mean square of the successive difference in R-R interval [RMSSD]) r=0.75, P = 0.01 and and log high frequency [HF] r=0.66, P = 0.02), but not cBRS (all, r ≤ 0.2, P > 0.05). Post-exercise hypotension was greater after exercise in a hot compared to a temperate environment and may be partially explained by greater sweat loss and cutaneous vascular conductance, and lower HRV.

Analysis of time-domain indices, frequency domain measures of heart rate variability derived from ECG waveform and pulse-wave-related HRV among overweight individuals: an observational study

Background: Research on the compatibility of time domain indices, frequency domain measurements of heart rate variability obtained from electrocardiogram (ECG) waveforms, and pulse wave signal (pulse rate variability; PRV) features is ongoing. The promising marker of cardiac autonomic function is heart rate variability. Recent research has looked at various other physiological markers, leading to the emergence of pulse rate variability. The pulse wave signal can be studied for variations to understand better changes in arterial stiffness and compliance, which are key indicators of cardiovascular health. Methods: 35 healthy overweight people were included. The Lead II electrocardiogram (ECG) signal was transmitted through an analog-to-digital converter (PowerLab 8/35 software, AD Instruments Pty. Ltd., New South Wales, Australia). This signal was utilized to compute Heart Rate Variability (HRV) and was sampled at a rate of 1024 Hz. The same AD equipment was also used to capture a pulse signal simultaneously. The right index finger was used as the recording site for the pulse signal using photoplethysmography (PPG) technology. Results: The participants' demographic data show that the mean age was 23.14 + 5.27 years, the mean weight was 73.68 +  7.40 kg, the mean body fat percentage was 32.23   +  5.30, and the mean visceral fat percentage was 4.60   +  2.0. The findings revealed no noticeable difference between the median values of heart rate variability (HRV) and PRV. Additionally, a strong correlation was observed between HRV and PRV. However, poor agreement was observed in the measurement of PRV and HRV. Conclusion: All indices of HRV showed a greater correlation with PRV. However, the level of agreement between HRV and PRV measurement was poor. Hence, HRV cannot be replaced with PRV and vice-versa.

Physical activity trajectories, autonomic balance and cognitive function: The Coronary Artery Risk Development in Young Adults (CARDIA) study

Physical activity (PA) plays an important role in cognitive health. However, the underlying mechanisms are not fully understood. Cardiac autonomic balance is influenced by PA and implicated in dementia pathogenesis. We examined whether autonomic balance mediates the association between PA and cognitive function. The sample included 1939 participants from the Coronary Artery Risk Development in Young Adults study who completed cognitive testing after 30-year follow-up (baseline: mean age 25.2 ± 3.5y; 58% women; 43% Black). Moderate to vigorous intensity PA (MVPA) was obtained in 7 consecutive examinations over 20 years (Year 0-Year 20). Cardiac autonomic balance was assessed at Year 20 via resting heart rate (RHR), standard deviation normal to normal (SDNN) and root mean square of successive differences (RMSSD). We used group-based trajectory modeling to identify homogenous MVPA trajectory groups, and formal mediation analysis to test whether autonomic function indices mediate the association between MVPA trajectories and cognition. We identified three distinct PA trajectory patterns: (1) Below MVPA guidelines (n = 1122; 57.9%); (2) Meeting MVPA guidelines (n = 652; 33.6%); and (3) Exceeding MVPA guidelines (n = 165; 8.5%). Meeting and exceeding MVPA guidelines were related to better autonomic balance overall, and to improved semantic fluency performance. Statistically, the association between higher MVPA level and verbal ability was mediated by SDNN and RMSSD, but not by RHR. In our sample of young and middle-aged adults, higher MVPA levels over time were associated with better cardiac autonomic function, which explained some of the associations between PA trajectories and better cognition.

Associations between personal noise exposure and heart rate variability were modified by obesity and PM2.5: The study among obese and normal-weight adults (SONA)

Noise pollution has been documented to increase the risks of cardiovascular disorders, which can be predicted by heart rate variability (HRV), nevertheless, there has been limited evidence on the modifiers of noise pollution. Environmental fine particulate matter (PM_2.5) and obesity status are both growing major concerns of cardiovascular disease burden. Our study aims to investigate whether these two factors may modify the associations between noise exposure and HRV indices. An investigation was performed on 97 (53 normal-weight and 44 obese) participants aged 18-26 years, with continuous 5-min personal exposure assessment and ambulatory electrocardiogram monitoring for 24 h. This study found that personal exposure to noise was associated with decreased HRV level and imbalanced cardiac autonomic function, as indicated by decreases in standard deviation of normal-to-normal intervals (SDNN), square root of the mean squared differences of successive intervals (rMSSD), the percentage of R-R intervals that differ from each other by more than 50 ms (pNN50), low-frequency (LF) power, high-frequency (HF) power, and increases in LF-HF-Ratio. Stronger associations between personal noise exposure and HRV indices were observed among obese participants and participants with higher PM_2.5 exposure levels compared to their counterparts. For SDNN, a 1 dB(A) increment in personal noise exposure at 3h-average was associated with a 1.25% (95%CI: -1.64%, -0.86%) decrease among obese participants, and a 0.11% (95%CI: -0.38%, 0.16%) decrease among normal-weight participants (P for subgroup difference<0.001); and a 0.87% (95%CI: -1.20%, -0.54%) decrease among participants with higher PM_2.5 exposure levels, and a 0.22% (95%CI: -0.58%, 0.14%) decrease among participants with lower PM_2.5 exposure levels (P for subgroup difference = 0.008). Obesity and PM_2.5 may aggravate the adverse effects of noise on HRV, which has implications for targeted prevention of cardiovascular disease burden associated with noise pollution.

Exploring of cardiac autonomic activity with heart rate variability in long-term kratom (Mitragyna speciosa Korth.) users: a preliminary study

Background

Kratom is a psychoactive plant used to enhance productivity among laborers in Southeast Asian countries. Previous findings from in vitro research of mitragynine, a major component of kratom, suggested a possible risk of heart function abnormality. However, the cardiac autonomic function in long-term kratom users with chewing forms has never been studied. This study aimed to investigate heart rate variability (HRV) indices of cardiac autonomic function in long-term kratom chewers (LKC), compared to the control levels, and also to examine the correlation between HRV indices and relevant kratom use factors.

Method

A total number of 50 participants consisted of LKC (n = 31) who regularly chewed fresh kratom leaves for at least 2 years and demographically matched control subjects (n = 19). Resting electrocardiogram (ECG) signals were recorded from subjects for 3 min to analyze the ultrashort HRV in the frequency domain. The normalized low frequency (LFn) and high frequency (HFn) were chosen to be the HRV indices to evaluate cardiac autonomic function. The comparison of HRV indices between groups and the correlation between HRV indices and duration and quantity of kratom use was further conducted in statistical analysis.

Results

The LKC significantly increased LFn together with enhanced HFn compared to the control group tested, indicating that LKC changed cardiac autonomic function with parasympathetic dominance. Furthermore, no significant correlation between the HRV indices and the duration and quantity of kratom use was found, suggesting that the HRV indices were not relevant to these factors. The present study provided scientific-based evidence of cardiac autonomic modulation in long-term kratom chewers. LFn and HFn may be promising cardiac autonomic indicators for monitoring health outcomes in LKC.

High-intensity interval training for 12 weeks improves cardiovascular autonomic function but not somatosensory nerve function and structure in overweight men with type 2 diabetes

AIMS/HYPOTHESIS

It remains unclear whether and which modality of exercise training as a component of lifestyle intervention may exert favourable effects on somatosensory and autonomic nerve tests in people with type 2 diabetes.

METHODS

Cardiovascular autonomic and somatosensory nerve function as well as intraepidermal nerve fibre density (IENFD) were assessed in overweight men with type 2 diabetes (type 2 diabetes, n = 20) and male glucose-tolerant individuals (normal glucose tolerance [NGT], n = 23), comparable in age and BMI and serving as a control group, before and after a supervised high-intensity interval training (HIIT) intervention programme over 12 weeks. Study endpoints included clinical scores, nerve conduction studies, quantitative sensory testing, IENFD, heart rate variability, postural change in systolic blood pressure and spontaneous baroreflex sensitivity (BRS).

RESULTS

After 12 weeks of HIIT, resting heart rate decreased in both groups ([mean ± SD] baseline/12 weeks: NGT: 65.1 ± 8.2/60.2 ± 9.0 beats per min; type 2 diabetes: 68.8 ± 10.1/63.4 ± 7.8 beats per min), while three BRS indices increased (sequence analysis BRS: 8.82 ± 4.89/14.6 ± 11.7 ms²/mmHg; positive sequences BRS: 7.19 ± 5.43/15.4 ± 15.9 ms²/mmHg; negative sequences BRS: 12.8 ± 5.4/14.6 ± 8.7 ms²/mmHg) and postural change in systolic blood pressure decreased (-13.9 ± 11.6/-9.35 ± 9.76 mmHg) in participants with type 2 diabetes, and two heart rate variability indices increased in the NGT group (standard deviation of R-R intervals: 36.1 ± 11.8/55.3 ± 41.3 ms; coefficient of R-R interval variation: 3.84 ± 1.21/5.17 ± 3.28) (all p<0.05). In contrast, BMI, clinical scores, nerve conduction studies, quantitative sensory testing, IENFD and the prevalence rates of diabetic sensorimotor polyneuropathy and cardiovascular autonomic neuropathy remained unchanged in both groups. In the entire cohort, correlations between the changes in two BRS indices and changes in [Formula: see text] over 12 weeks of HIIT (e.g. sequence analysis BRS: r = 0.528, p=0.017) were observed.

CONCLUSIONS/INTERPRETATION

In male overweight individuals with type 2 diabetes, BRS, resting heart rate and orthostatic blood pressure regulation improved in the absence of weight loss after 12 weeks of supervised HIIT. Since no favourable effects on somatic nerve function and structure were observed, cardiovascular autonomic function appears to be more amenable to this short-term intervention, possibly due to improved cardiorespiratory fitness.

Evaluation of Heart Rate Variability and Application of Heart Rate Variability Biofeedback: Toward Further Research on Slow-Paced Abdominal Breathing in Zen Meditation

This review summarizes my own involvement in heart rate variability (HRV) and HRV biofeedback studies, as a tribute to the late Dr. Evgeny Vaschillo. I first review psychophysiological studies on behavioral stress and relaxation performed in my laboratory using an assessment of cardiac parasympathetic activity. Although magnitude of high-frequency (HF) component of HRV corresponding respiratory sinus arrhythmia (RSA) is widely used as an index of cardiac parasympathetic function, a respiratory confound during stress or relaxation may have interfered with the proper assessment of the HF HRV. An enhanced method under frequency-controlled respiration at 0.25 Hz provided a reliable assessment of cardiac parasympathetic activity. I then review findings from HRV biofeedback research in my laboratory. Based on the hypothesis that RSA measured as an HF component of HRV represents cardiorespiratory resting function, it was demonstrated that HRV biofeedback before sleep enhanced the magnitude of HF HRV during sleep, a cardiorespiratory resting function. Moreover, by focusing on the spectral peak of the low-frequency (LF) component of HRV, paced breathing at the LF-peak frequency was shown to increase baroreflex sensitivity. Finally, I describe the potential of slow-paced abdominal breathing (i.e., Tanden breathing) performed in Zen meditation. The concept of Tanden breathing as described in a regimen from early modern Japan is introduced, and recent research findings on slow-paced abdominal breathing are summarized. Future research directions of slow-paced abdominal breathing are also discussed.

Does obstructive sleep apnoea modulate cardiac autonomic function in paroxysmal atrial fibrillation?

PURPOSE

The autonomic nervous system may mediate acute apnoea-induced atrial fibrillation (AF). We compared cardiac autonomic function in paroxysmal atrial fibrillation (PAF) patients with and without obstructive sleep apnoea (OSA).

METHODS

Case control study of 101 patients with PAF recruited at two tertiary centres. All patients underwent in-laboratory polysomnography. ECG signal demonstrating "steady state" sinus rhythm (i.e. with arrhythmic beats and respiratory events excluded) was included in the analysis. Cardiac autonomic function was assessed via measures of heart rate variability (HRV) and reported by sleep stage (REM vs Non-REM) for patients with and without OSA.

RESULTS

Sixty-five (66.3%) of patients were male, mean age 61.5 ± 11.6 years, mean BMI 27.1 ± 4.3 kg/m². Global measures of HRV (triangular index, total power) did not differ between PAF patients with and without OSA in either REM or non-REM sleep. Frequency-domain analysis during non-REM sleep in PAF patients with OSA showed increased cardiac parasympathetic modulation (HF-nu: 39.1 ± 15.7 vs 48.0 ± 14.6, p = 0.008) and reduced cardiac sympathetic modulation (LF-nu 54.1 ± 19.7 vs 43.7 ± 18.0, p = 0.012, LF/HF ratio: 2.1 ± 2.0 vs 1.2 ± 1.0, p = 0.007). Results remained significant after adjusting for age, sex, and BMI (adjusted p values 0.024, 0.045 and 0.018 respectively). There were no differences in HRV parameters during REM sleep.

CONCLUSIONS

This is the first study of HRV in PAF patients with and without OSA. Our results indicate limited differences in HRV between groups. However, this work suggests a chronic increase in parasympathetic nervous modulation and relative reduction in sympathetic modulation in PAF patients with OSA during steady-state non-REM sleep.

The impact of age, type 2 diabetes and hypertension on heart rate variability during rest and exercise at increasing levels of heat stress

PURPOSE

In older adults with type 2 diabetes (T2D) and hypertension (HTN), cardiac autonomic modulation is markedly attenuated during exercise-heat stress. However, the extent to which this impairment is evident under increasing levels of heat stress remains unknown.

METHODS

We examined heart rate variability (HRV), a surrogate of cardiac autonomic modulation, during incremental exercise-heat stress exposures in young (20-30 years) and middle-aged-to-older individuals (50-70 years) without and with T2D and HTN. Thirteen young and healthy (Young, n = 13) and 37 older men without (Older, n = 14) and with HTN (n = 13) or T2D (n = 10) performed 180-min treadmill walking at a fixed metabolic rate (~ 200 W/m²; ~ 3.5 METs) in a differing wet-bulb globe temperature (WBGT; 16 °C, 24 °C, 28 °C, and 32 °C). Electrocardiogram (ECG) and core temperature measurements were recorded throughout. Data were analysed using 5-min averaged epochs following 60-min exercise, which represented the last common timepoint across groups and conditions.

RESULTS

Ageing did not significantly reduce HRV during increasing exercise-heat stress (all p > 0.050). However, T2D and HTN modified HRV during exercise-heat stress such that Detrended Fluctuation Analysis (DFA) α₁ (p = 0.012) and the cardiac sympathetic index (p = 0.037) were decreased compared to Older in all except the warmest WBGT condition (32 °C).

CONCLUSION

Our unique observations indicate that, relative to their younger counterparts, HRV in healthy older individuals is not perturbed during exercise heat-stress. However, relative to their age-matched healthy counterparts, HRV is reduced during exercise-heat stress in individuals with age-associated chronic conditions, indicative of cardiac autonomic dysfunction.

Cardiac autonomic functioning and clinical outcome in adolescent borderline personality disorder over two years

The present study aimed to expand on previous findings that pre-treatment autonomic nervous system (ANS) functioning serves as a predictor of clinical outcome in adolescent borderline personality disorder (BPD), while examining whether the relationship between ANS functioning and treatment outcome may vary as a function of early life maltreatment (ELM). ANS stress response was examined considering changes in heart rate (HR) and vagally-mediated heart rate variability (vmHRV) over different conditions of the Montreal Imaging Stress Task (MIST) in a clinical sample of N = 27 adolescents across the spectrum of BPD severity. Participants received in- and/or outpatient treatment, while clinical data was assessed at routine follow-ups. Clinical outcome was defined by change in the number of fulfilled BPD criteria (as measured using the SCID-II), severity of psychopathology (CGI-S), and global level of functioning (GAF), measured 12 and 24 months after baseline assessments. Mixed-effects (random-intercept/random slope) linear regression models were calculated to examine markers of ANS function as potential predictors of clinical outcome. Irrespective of the presence of ELM exposure, both vmHRV resting-state and stress recovery measures were identified as significant predictors of clinical outcome over time. This study adds to the existing literature by replicating and expanding on preliminary findings, considering also physiological reactivity and recovery in addition to resting-state measures of ANS functioning. The present results further highlight the potential of markers of ANS functioning to serve as objective measures in the process of monitoring patient progress and to make predictions regarding treatment outcome in psychiatry research.

Assessment of parasympathetic cardiovascular activity in primary open-angle glaucoma

PURPOSE

To describe the pattern of quantitative parasympathetic cardiovascular autonomic function among patients with normal-tension glaucoma (NTG) and high-tension primary open-angle glaucoma (HTG) patients.

METHODOLOGY

This was cross-sectional study of ninety-two subjects enrolled into three groups: HTG (31 patients), NTG (31 patients) and Control (30 patients). All the participants had anthropometric assessment, ophthalmic examination, baseline cardiovascular examination and the three parasympathetic components of Ewing's battery of autonomic cardiovascular function tests namely heart rate (HR) response to deep breathing, HR response to Valsalva manoeuvre and HR response to standing.

RESULT

The baseline PR intervals were significantly prolonged in HTG (0.18 ± 0.03 s) and NTG (0.18 ± 0.04 s) groups compared with control (0.15 ± 0.03 s) (p = 0.008). The HTG group had a significantly longer mean RR interval (1.09 ± 0.17 s) than the NTG group (1.03 ± 0.20 s) and control (0.97 ± 0.17 s) during the expiratory phase of the HR response to deep breathing test (p = 0.037). The HTG group also had significantly longer mean RR intervals around the 15th beat (p = 0.033) and 30th beats (p = 0.202) post-standing during the HR response to standing test. The HR response to Valsalva manoeuvre test showed a significantly higher mean Valsalva ratio in the NTG group (1.65 ± 0.48) compared to the HTG group (1.45 ± 0.31) and control (1.43 ± 0.25) (p = 0.034).

CONCLUSION

This study demonstrated that normal-tension and high-tension primary open-angle glaucoma have higher parasympathetic cardiovascular activity than normal individuals.

Exploring the effects of oily fish consumption on measures of acute and long-term stress in healthy 8-9-year-old children: the FiSK Junior randomised trial

Long-chain n-3 PUFA (n-3 LCPUFA) are known to reduce blood pressure (BP), heart rate and vagal tone, but potential stress-mitigating effects of n-3 LCPUFA are not well investigated. We explored the effects of oily fish consumption on long-term stress and the stress response in schoolchildren. Healthy 8-9-year-old children were randomised to receive about 300 g/week of oily fish or poultry for 12 weeks (199 randomised, 197 completing). At baseline and endpoint, we measured erythrocyte n-3 LCPUFA, hair cortisol and the response to a 1-min cold pressor test (CPT) on saliva cortisol, BP and continuous electrocardiogram recordings. Post-intervention hair cortisol did not differ between the groups, but sex-specificity was indicated (Psex × group = 0·074, boys: -0·9 (95 % CI -2·9, 1·0) ng/g, girls: 0·7 (95 % CI -0·2, 1·6) ng/g). Children in the fish group tended to be less prone to terminate CPT prematurely (OR 0·20 (95 % CI 0·02, 1·04)). Mean heart beat interval during CPT was 18·2 (95 % CI 0·3, 36·6) ms longer and high frequency power increased (159 (95 % CI 29, 289) ms2) in the fish v. poultry group. The cardiac autonomic response in the 10 min following CPT was characterised by a sympathetic peak followed by a parasympathetic peak, which was most pronounced in the fish group. This exploratory study does not support a strong effect of oily fish consumption on stress but indicates that oily fish consumption may increase vagal cardiac tone during the physiological response to CPT. These results warrant further investigation.

Cardiac autonomic function and cognitive performance in patients with atrial fibrillation

Background

Atrial fibrillation (AF) is associated with loss of cognition and dementia. Cardiac autonomic dysfunction has been linked to cognitive decline. We aimed to investigate if reduced cardiac autonomic function (CAF) is associated with cognitive impairment in AF patients.

Methods

Patients with paroxysmal, persistent and permanent AF were enrolled from a multicenter cohort study if they had AF (“AF group”) or sinus rhythm (“SR group”) on a baseline 5 min ECG recording. Parameters quantifying CAF (heart rate variability triangular index (HRVI), mean heart rate (MHR), RMSSD, SDNN, total power and power in the VLF, LF, HF ranges) were calculated. We used the Montreal Cognitive Assessment (MoCA) to assess global cognitive function.

Results

1685 AF patients with a mean age of 73 ± 8 years, 29% females, were included. MoCA score was 24.5 ± 3.2 in the AF group (N = 710 patients) and 25.4 ± 3.2 in the SR group (N = 975 patients). After adjusting for multiple confounders, lower HRVI was associated with lower MoCA scores, both in the SR group [β = 0.049; 95% confidence interval (CI) 0.016–0.081; p = 0.003] and in the AF group (β = 0.068; 95% CI 0.020–0.116; p = 0.006). In the AF group, higher MHR was associated with a poorer performance in the MoCA (β =  − 0.008; 95% CI − 0.014 to − 0.002; p = 0.014). We found no convincing evidence of association for other CAF parameters with cognition.

Conclusion

Our data suggest that impaired CAF is associated with worse cognitive performance in patients with AF. Among standard HRV parameters, HRVI might be the most promising ECG index.

Trial registration

ClinicalTrials.gov Identifier: NCT02105844.

Graphic abstract

Supplementary Information

The online version contains supplementary material available at 10.1007/s00392-021-01900-4.

Bariatric Surgery in Adults with Obesity: the Impact on Performance, Metabolism, and Health Indices

This systematic review summarizes current evidence on the impact of bariatric surgery (BS) on physical performance, metabolic, and health indices in adults with obesity. This systematic review suggests that BS induced significant reductions in body weight, fat mass, and fat-free mass in individuals with obesity. Additionally, BS may improve many physical fitness and health indicators. Observed improvements manifest during a distinct period of time. To date, studies on BS and performance have been small in number, nonrandomized in design, and not controlled regarding gender distribution and/or post-surgery follow-up. Future studies should further investigate concerns associated with understanding of BS outcomes to improve these outcomes with potential benefits for quality of life, disability, mortality, morbidity, and overall BS success.

Exercise Enhances the Effect of Bariatric Surgery in Markers of Cardiac Autonomic Function

BACKGROUND

Bariatric surgery improves cardiovascular health, which might be partly ascribed to beneficial alterations in the autonomic nervous system. However, it is currently unknown whether benefits from surgery on cardiac autonomic regulation in post-bariatric patients can be further improved by adjuvant therapies, namely exercise. We investigated the effects of a 6-month exercise training program on cardiac autonomic responses in women undergoing bariatric surgery.

METHODS

Sixty-two women eligible for bariatric surgery were randomly allocated to either standard of care (control) or an exercise training intervention. At baseline (PRE) and 3 (POST3) and 9 (POST9) months after surgery, we assessed chronotropic response to exercise (CR%; i.e., percentage change in heart rate from rest to peak exercise) and heart rate recovery (HRR30s, HRR60s, and HRR120s; i.e., decay of heart rate at 30, 60, and 120 s post exercise) after a maximal exercise test.

RESULTS

Between-group absolute changes revealed higher CR% (Δ = 8.56%, CI95% 0.22-19.90, P = 0.04), HRR30s (Δ = 12.98 beat/min, CI95% 4.29-21.67, P = 0.01), HRR60s (Δ = 22.95 beat/min, CI95% 11.72-34.18, P = 0.01), and HRR120s (Δ = 34.54 beat/min, CI95% 19.91-49.17, P < 0.01) in the exercised vs. non-exercised group.

CONCLUSIONS

Our findings demonstrate that exercise training enhanced the benefits of bariatric surgery on cardiac autonomic regulation. These results highlight the relevance of exercise training as a treatment for post-bariatric patients, ensuring optimal cardiovascular outcomes.

The effects of non-invasive mechanical ventilation on cardiac autonomic dysfunction in spinal muscular atrophy

In patients with spinal muscular atrophy (SMA), obstructive sleep apnea syndrome (OSAS) constitutes an important cause of cardiovascular morbidity and mortality. We investigated heart rate variability (HRV) to evaluate the effects of non-invasive mechanical ventilation on cardiac autonomic dysfunction in patients with SMA and OSAS. Six patients with SMA (type 1 and 2) and six age- and sex-matched healthy children were consecutively enrolled. A whole-night diagnostic polysomnography was performed, and SMA patients with OSAS were given non-invasive mechanical ventilation therapy. HRV analysis was performed on the basis of whole-night electrocardiography recordings via a computer-base program. Apnea-hypopnea index (AHI) was 9.2 ± 6.2/hr in SMA patients, while it was 0.4 ± 0.5/hr in controls (p = 0.036). All SMA patients had OSAS, while none of the controls had OSAS (p = 0.012). Mean percentage of successive R wave of QRS complex (R-R) intervals>50 ms was significantly lower in SMA patients than those in controls (p = 0.031). Significant correlations were found between AHI and high-frequency power, low/high-frequency ratio in wakefulness and in sleep (p<0.05). Repeated HRV analysis in SMA patients following OSAS therapy showed significant reductions in average R-R duration (p = 0.028) and percentage of successive R-R intervals>50 ms (p = 0.043). Our study demonstrates the beneficial effects of non-invasive mechanical ventilation on cardiac autonomic dysfunction in SMA patients with OSAS.

Cardiac autonomic and blood pressure responses to an acute session of battling ropes exercise

BACKGROUND

Battling rope (BTR) exercise has become incredibly popular among not only fitness enthusiasts and athletes but in the general exercising population. Despite its popularity, research regarding the acute cardiovascular responses to BTR exercise is limited. This investigation evaluated the effects of acute BTR exercise on heart rate variability (HRV) and blood pressure (BP) responses in young men with elevated BP.

MATERIALS AND METHODS

Eleven young men with elevated BP completed either a BTR or a non-exercise control trial in randomized order. The BTR trial consisted of 10 rounds of BTR exercise. Each round included 30 s of exercise followed by 30 s of rest. HRV and BP were evaluated at baseline and 3, 10, and 30 min following each trial.

RESULTS

There were significant elevations (p ˂0.01) in heart rate, markers of sympathetic activity (nLF), and sympathovagal balance (LnLF/LnHF, nLF/nHF) for 30 min following the BTR trial, whereas no changes from baseline were detected after control. Additionally, there were significant reductions (p ˂0.01) in markers of vagal tone (RMSSD, LnHF and nHF) and LnLF (both sympathetic and vagal modulations) for 30 min; as well as (p ˂0.01) systolic BP and diastolic BP at 10 and 30 min after the BTR, but not the control trial.

CONCLUSION

Current findings revealed that BTR exercise elevates sympathovagal balance for 30 min post-intervention, which is concurrent with an impressive hypotensive effect. Further investigations are warranted to assess the potential clinical application of BTR exercise not only in cohorts needing BP control but also in populations with limited locomotion that might benefit from post-exercise hypotension.

Effects of a short health education intervention on physical activity, arterial stiffness and cardiac autonomic function in individuals with moderate-to-high cardiovascular risk

OBJECTIVE

This study evaluated the effects of a short health education and counseling intervention program, in a primary healthcare setting, on daily physical activity (PA), arterial stiffness, and cardiac autonomic function in individuals with moderate-to-high risk of cardiovascular disease.

METHODS

This was a parallel-group study with a 4-month-long intervention, plus 8 months of follow-up. 164 individuals with moderate-to-high cardiovascular risk were allocated to either an intervention (n = 87) or a control group (n = 77). The intervention consisted of 3 walking and face-to-face group sessions plus text messages. Primary outcome was daily PA (sedentary time, light and moderate-to-vigorous PA, all in min/day); secondary outcomes were arterial stiffness i.e., carotid-femoral pulse wave velocity (cfPWV, m/s)] and cardiac autonomic function [(i.e., standard deviation of all N-N intervals (SDNN, ms) and absolute high frequency (HF, ms²)].

RESULTS

There were not significant group*time interactions for sedentary time [-7.4 (7.6); p = 0.331)], light PA [4.4 (6.4); p = 0.491] or moderate-to-vigorous PA [0.1 (2.6); p = 0.938]. Considering secondary outcomes, there were not significant group*time interactions for cfPWV [0.09 (0.18); p = 0.592], Ln_SDNN [0.09 (0.06); p = 0.148], or Ln_HF [0.16 (0.14); p = 0.263].

CONCLUSION

The program did not improve daily PA, arterial stiffness, or the autonomic cardiac function.

PRACTICE IMPLICATIONS

Primary care staff should consider longer or other types of intervention to improve daily PA.

Obstructive sleep apnea syndrome and autonomic dysfunction in Duchenne muscular dystrophy

PURPOSE

Cardiac and respiratory involvement constitutes serious complications of Duchenne muscular dystrophy (DMD). We hypothesized that obstructive sleep apnea syndrome (OSAS) may play a role in cardiac autonomic dysfunction in DMD. We sought to assess the presence of cardiac autonomic function in patients with DMD by analyzing heart rate variability (HRV) during polysomnography (PSG).

METHODS

In a prospective study, all participants had whole-night PSG recorded and scored according to American Academy of Sleep Medicine guidelines. HRV analysis was performed on electrocardiography recordings from PSG recordings.

RESULTS

Twelve consecutive males with DMD (mean age 9.0 ± 3.1 years, mean BMI 20.6 ± 4.8 kg/m2) and eight age-matched healthy males were enrolled. On clinical evaluation, 58% of patients with DMD had at least one symptom related to OSAS, such as snoring, witnessed apnea, or restless sleep. None of the controls had OSAS-related complaints. By PSG none of the controls had OSAS, while 42% of patients with DMD had OSAS (p = 0.004). Average R-R duration and mean percentage of successive R-R intervals > 50 ms values were significantly lower in patients with DMD than those in controls (p < 0.006). In patients with DMD and OSAS, LF/HF (low/high-frequency) ratio was significantly increased in NREM sleep compared with those in controls (p = 0.005). Higher apnea-hypopnea index and lower oxygen saturation showed significant correlations with higher LF power and LF/HF ratio (p < 0.001).

CONCLUSION

Cardiac autonomic dysfunction is present in DMD, being more pronounced in the presence of OSAS.

Insulin resistance and reduced cardiac autonomic function in older adults: the Atherosclerosis Risk in Communities study

Background

Prior studies have shown insulin resistance is associated with reduced cardiac autonomic function measured at rest, but few studies have determined whether insulin resistance is associated with reduced cardiac autonomic function measured during daily activities.

Methods

We examined older adults without diabetes with 48-h ambulatory electrocardiography (n = 759) in an ancillary study of the Atherosclerosis Risk in Communities Study. Insulin resistance, the exposure, was defined by quartiles for three indexes: 1) the homeostatic model assessment of insulin resistance (HOMA-IR), 2) the triglyceride and glucose index (TyG), and 3) the triglyceride to high-density lipoprotein cholesterol ratio (TG/HDL-C). Low heart rate variability, the outcome, was defined by <25th percentile for four measures: 1) standard deviation of normal-to-normal R-R intervals (SDNN), a measure of total variability; 2) root mean square of successive differences in normal-to-normal R-R intervals (RMSSD), a measure of vagal activity; 3) low frequency spectral component (LF), a measure of sympathetic and vagal activity; and 4) high frequency spectral component (HF), a measure of vagal activity. Logistic regression was used to estimate odds ratios (OR) and 95% confidence intervals weighted for sampling/non-response, adjusted for age at ancillary visit, sex, and race/study-site. Insulin resistance quartiles 4, 3, and 2 were compared to quartile 1; high indexes refer to quartile 4 versus quartile 1.

Results

The average age was 78 years, 66% (n = 497) were women, and 58% (n = 438) were African American. Estimates of association were not robust at all levels of HOMA-IR, TyG, and TG/HDL-C, but suggest that high indexes were associated consistently with indicators of vagal activity. High HOMA-IR, high TyG, and high TG/HDL-C were consistently associated with low RMSSD (OR: 1.68 (1.00, 2.81), OR: 2.03 (1.21, 3.39), and OR: 1.73 (1.01, 2.91), respectively). High HOMA-IR, high TyG, and high TG/HDL-C were consistently associated with low HF (OR: 1.90 (1.14, 3.18), OR: 1.98 (1.21, 3.25), and OR: 1.76 (1.07, 2.90), respectively).

Conclusions

In older adults without diabetes, insulin resistance was associated with reduced cardiac autonomic function – specifically and consistently for indicators of vagal activity – measured during daily activities. Primary prevention of insulin resistance may reduce the related risk of cardiac autonomic dysfunction.

Evaluation of the relationship between cardiac autonomic function and glucose variability and HOMA-IR in prediabetes

AIMS

The present study aims to investigate the relationship between cardiac autonomic function (CAF) and glucose variability (GV) and HOMA-IR in subjects with prediabetes and normal glucose tolerance (NGT).

MATERIAL AND METHODS

Ninety-two subjects (59 with prediabetes and 33 with NGT), of mean age 50.3 ± 11.5 years, mean BMI 30.4 ± 6.0 kg/m², were included in this cross-sectional study. Glucose tolerance was assessed by OGTT according to WHO 2006 criteria. Glucose, HbA1c, insulin, oxLDL, and 3-Nitrotyrosine were measured. CGM was performed with a blinded sensor (FreeStyle Libre Pro). CAF was assessed by ANX-3.0 technology.

RESULTS

GV indices were increased in prediabetes. CAF was suppressed in subjects with any stage of dysglycemia. The prevalence of cardiac autonomic dysfunction was higher in prediabetes -20.3% as compared to NGT -3.0%, p = 0.028. HOMA-IR [OR 1.5 (95% CI: 1.1-2.1), p = 0.010] and time in target range [OR 0.8 (95% CI: 0.67-0.97), p = 0.021] were found to be predictive variables for impaired CAF. Sympathetic and parasympathetic activity negatively correlated with mean glycemia and GV indices and were independently related to JINDEX in prediabetes (F[1, 47] = 5.76, p = 0.021 and F[1, 47] = 5.94, p = 0.019, respectively); and to time above target range in NGT (F[1, 18] = 4.48, p = 0.049 and F[1, 18] = 4.65, p = 0.046, respectively).

CONCLUSION

CAF is declined in prediabetes and seems to be related to GV and HOMA-IR at early stages of dysglycemia.

Vitamin D binding protein is related to cardiac autonomic function and metabolic status in prediabetes

A putative causal relationship between vitamin D status and glucose metabolism and a direct effect of vitamin D on cardiac autonomic function (CAF) have been suggested. We hypothesized that vitamin D binding protein (DBP), as a transporter of vitamin D, might also influence CAF and the overall metabolic risk. The present study aims to assess the relationship between DBP and CAF and metabolic status in a high-risk population with prediabetes. A total of 174 subjects (mean age 49.1±12.9 years, mean body mass index 30.2±6.2 kg/m²) were divided into 2 groups according to glucose tolerance: 48 with normal glucose tolerance and 126 with prediabetes. Glucose tolerance was assessed during oral glucose tolerance test, applying 2006 World Health Organization criteria. Fasting and postload glucose and immunoreactive insulin were measured (homeostatic model assessment of insulin resistance and homeostatic model assessment of β-cell function were calculated). Anthropometric indexes, blood pressure, hemoglobin A1c, creatinine, lipids, high-sensitivity C-reactive protein, total 25-hydroxyvitamin D, DBP (free 25-hydroxyvitamin D was calculated), and intact parathormone were measured. Body composition was estimated by impedance analysis (InBody 720), whereas tissue advanced glycation end products were assessed by skin autofluorescence (AGE Reader, DiagnOptics, the Netherlands). CAF was evaluated by АNX-3.0 system, applying standard autonomic tests. DBP was found to be elevated in women, as well as in the presence of cardiac autonomic dysfunction and metabolic syndrome. DBP was related to parasympathetic activity in both sexes and in prediabetes; to body fat in women and in prediabetes; and to age and high-density lipoprotein cholesterol in men. Vitamin D deficiency was established in 40.8% of the studied cohort. These results support the hypothesis that DBP is associated with CAF and some metabolic parameters in prediabetes.

Different cardiorespiratory effects of indoor air pollution intervention with ionization air purifier: Findings from a randomized, double-blind crossover study among school children in Beijing

Indoor air pollution is associated with numerous adverse health outcomes. Air purifiers are widely used to reduce indoor air pollutants. Ionization air purifiers are becoming increasingly popular for their low power consumption and noise, yet its health effects remain unclear. This randomized, double-blind crossover study is conducted to explore the cardiorespiratory effects of ionization air purification among 44 children in Beijing. Real or sham purification was performed in classrooms for 5 weekdays. Size-fractionated particulate matter (PM), black carbon (BC), ozone (O₃), and negative air ions (NAI) were monitored, and cardiorespiratory functions were measured. Mixed-effect models were used to establish associations between exposures and health parameters. Real purification significantly decreased PM and BC, e.g. PM_0.5, PM_2.5, PM₁₀ and BC were decreased by 48%, 44%, 34% and 50%, respectively. O₃ levels were unchanged, while NAI was increased from 12 cm^-3 to 12,997 cm^-3. Real purification was associated with a 4.4% increase in forced exhaled volume in 1 s (FEV₁) and a 14.7% decrease in fractional exhaled nitrogen oxide (FeNO). However, heart rate variability (HRV) was altered negatively. Interaction effects of NAI and PM were observed only on HRV, and alterations in HRV were greater with high NAI. Ionization air purifier could bring substantial respiratory benefits, however, the potential negative effects on HRV need further investigation.

Relationship Between Resting Heart Rate Variability and Intermittent Endurance Performance in Novice Soccer Players

Purpose: This study examined the relationships between the Yo-Yo Intermittent Recovery Test level 1 (Yo-Yo IR1) and resting heart rate variability (HRV) and submaximal 5'-5' test derived measures in novice male soccer players. Methods: Forty players (11.54 ± 0.58 years) from a soccer academy participated in this study, performing physical tests on two different days, separated by 48 h, as follows: (day 1) resting HRV and Yo-Yo IR1 test, and (day 2) anthropometric assessments (for peak height velocity assessment [PHV]) and the 5'-5' test. The Pearson product-moment correlation coefficient was used to determine the correlations between Yo-Yo IR1 performance and the remaining variables. A partial correlation analysis was further performed using age, stature, body mass, distance to PHV, and age at PHV as "confounders." Results: The highest correlation score was observed between Yo-Yo IR1 performance and resting HRV, when the absolute age was used as confounder (r = 0.72; p < .05). Conclusions: We observed that a practical measure of parasympathetic activity at rest is largely associated with performance obtained during a traditional intermittent endurance performance test.

Heart rate recovery and blood pressure response during exercise testing in patients with microvascular angina

Background

Angina pectoris with a normal coronary angiogram, termed microvascular angina (MVA), is an important clinical entity; however, its causes remain unclear. Autonomic dysfunction is one of the possible causes. Therefore, this study aimed to investigate parasympathetic dysfunction assessed by heart rate recovery (HRR) and increased sympathetic activity assessed by exaggerated blood pressure (BP) response (EBPR) to exercise in MVA.

Methods

The study participants were consecutive patients with anginal chest pain who underwent both coronary angiography with an ergonovine provocation test and a treadmill exercise test between January 2008 and February 2015. Patients with significant coronary artery disease (coronary artery stenosis ≥50%) or significant coronary artery spasm (≥90%) were excluded. Based on the treadmill exercise test, patients were categorized into the microvascular angina (MVA) group (patients with uniform ST depression ≥1 mm) and the control group. HRR was defined as peak heart rate minus heart rate after a 1 min recovery; blunted HRR was defined as ≤12 beats/min. EBPR was defined as a peak exercise systolic BP ≥210 mmHg in men and ≥ 190 mmHg in women. These parameters were compared between patients with MVA and the controls.

Results

Among the 970 enrolled patients (mean age 53.1 years; female 59.0%), 191 (20.0%) were diagnosed with MVA. In baseline characteristics, the MVA group had older participants, female predominance, and a higher prevalence of hypertension. The MVA group showed significantly lower HRR 1 min (24.9 ± 15.9 vs. 31.3 ± 22.7, p <  0.001) compared with the control group. Moreover, the proportion of EBPR was significantly higher in the MVA group than in the control group (21.5% vs. 11.6%, p <  0.001). Multivariable logistic regression analysis showed that age (odds ratio (OR), 1.045; 95% confidence interval (CI), 1.026-1.064; p <  0.001), HRR 1 min (OR, 0.990; 95% CI, 0.982-0.999; p = 0.022), and EBPR (OR, 1.657; 95% CI, 1.074-2.554; p = 0.022) were independently associated with MVA.

Conclusion

HRR and EBPR were associated with MVA, which suggests a link between MVA and autonomic dysregulation.

Effect of yoga on cardiac autonomic dysfunction and insulin resistance in non-diabetic offspring of type-2-diabetes parents: A randomized controlled study

OBJECTIVE

The present study was aimed to determine the effect of yoga program on cardiac autonomic dysfunction and insulin resistance in non-diabetic offspring of diabetes parents.

METHODS

A randomized passive-controlled study was conducted on 64 non-diabetic offspring of type-2-diabetes parents (mean-age:25.17years). Yoga group participants received yoga training for 8 weeks. Heart-rate variability (HRV) indices: low frequency (LF), high frequency (HF) and LF/HF ratio; fasting blood glucose (FBG), oral glucose tolerance test (OGTT) and insulin resistance (IR) were estimated at baseline and after 8-weeks of intervention.

RESULTS

We found a significant decrease in LF (p = 0.005), LF/HF ratio (p = 0.004), IR (p < 0.001), OGTT (p = 0.003) and increase in HF (p = 0.022) in yoga group participants. Control group participants did not show any significant change in any variables.

CONCLUSIONS

Improvement in cardiac autonomic function and insulin resistance by yoga training implies that yoga can reduce the risk of development of diabetes in offspring of diabetes parents.

Short-term effects of particulate matter in metro cabin on heart rate variability in young healthy adults: Impacts of particle size and source

BACKGROUND

Metro system has become popular in urban areas. However, short-term effects of size-fractionated particulate matter (PM) on cardiac autonomic function in metro system remain unexplored.

OBJECTIVES

To explore the contribution of ambient PM to in-cabin PM and investigate the short-term effects of exposure to size-fractionated PM and black carbon (BC) in metro system on cardiac autonomic function in young healthy adults.

METHODS

Thirty nine young healthy adults were asked to travel in metro system during 9:00-13:00 on a weekends between March and May 2017. We performed continuous ambulatory electrocardiogram monitoring for each of them, and measured real-time size-fractionated PM, BC, nitrogen dioxide, nitric oxide, carbon dioxide, ozone, noise, temperature and relative humidity in metro cabin. We also collected the data of ambient PM_2.5 (aerodynamic diameter < 2.5 µm) concentrations in Beijing. Linear regression model was used to estimate the infiltration factor of ambient PM_2.5 to assess the relationship between metro cabin PM and ambient PM. Mixed-effects model was used to estimate the associations between changes in HRV parameters and PM_0.5 (aerodynamic diameter < 0.5 µm), PM_0.5-2.5 (aerodynamic diameter between 0.5 µm and 2.5 µm), PM_2.5-10 (aerodynamic diameter between 2.5 µm and 10 µm), and BC, respectively.

RESULTS

We found that size-fractionated PM in metro systems were significantly associated with HRV parameters. Per IQR (interquartile range) increase in PM_0.5 (1.6*10⁷/m³) in 1-h moving average concentration was associated with a 13.96% (95% CI: - 18.99%, - 8.61%) decrease in SDNN (standard deviation of normal-to-normal intervals). Similar inverse associations were found between size-fractionated PM exposure and LF (low frequency power), HF (high frequency power), respectively, and smaller particles had greater effects on HRV parameters at shorter lag time. Sex of participants modified the adverse associations between size-fractionated PM and HRV. An IQR of 1-h PM_0.5 increasing was associated with a decrease of 6.05% (95% CI: - 22.87%, - 14.44%) in males and a 34.87% (95% CI: - 49.59%, - 15.85%) in females in LF (P for interaction = 0.026). The infiltration factor of ambient PM_2.5 was 0.39 (95% CI: 0.33, 0.45). It is estimated that PM_2.5 originated from ambient air may account for 20.2% of the PM measured in metro cabin. Per IQR increase in BC (5.5 μg/m³) in 5-min, 1-h, and 2-h moving averages, a primary tracer for ambient PM from combustion source, was associated with decreases of 0.84% (95% CI: - 1.20%, - 0.47%), 2.22% (95% CI: - 3.20%, - 1.22%), and 4.44% (95% CI: - 6.28%, - 2.56%) in SDNN, respectively.

CONCLUSIONS

Short-term exposure to PM may disturb metro commuter's cardiac autonomic function, and the potential effects depend on the size of PM and the sex of commuters. Ambient PM from combustion source may have adverse effects on the cardiac autonomic function of passengers in cabin.

Effect of Sympatholytic Therapy on Circadian Cardiac Autonomic Activity in Non-Diabetic Chronic Kidney Disease

Although beta-blockade itself is not a first choice for chronic kidney disease (CKD) patients, alpha-beta-blockers (ABB) do improve their prognoses. This study's aim was to evaluate the effect of beta-selective-blockers (BSB) and ABB on circadian cardiac autonomic activity in CKD patients.The study consisted of 496 non-diabetic individuals who underwent 24-hour Holter monitoring (149 CKD patients and 347 controls without CKD). Using heart rate variability analysis, we evaluated the proportion of NN50 and the high-frequency component (reflecting parasympathetic activity), and low- to high-frequency ratio (reflecting sympathovagal balance). These indices were evaluated by regression analysis incorporating gender, age, related comorbidities, and medications. BSB increased vagal activity only in the day-time and not the night-time in controls. In CKD patients, BSB was significantly related to higher vagal activity throughout the day and with lower sympathovagal balance at night. The night sympathovagal balance of CKD patients taking ABB was significantly higher than that of CKD patients taking BSB, which was the only significant difference between the effects of BSB and ABB.The sympatholytic therapy effect is different depending on CKD presence and whether patients are treated with BSB or ABB. In CKD patients without severe heart failure, BSB could be associated with higher parasympathetic activity and lower sympathovagal balance compared to ABB.

Association patterns for size-fractioned indoor particulate matter and black carbon and autonomic function differ between patients with chronic obstructive pulmonary disease and their healthy spouses

BACKGROUND

The effect of health status on the relationship between particulate matter (PM) and black carbon (BC) and cardiac autonomic function has not been examined sufficiently directly comparing patients with healthy participants.

OBJECTIVES

To evaluate the association patterns between size-fractioned indoor PM and BC and cardiac autonomic function in chronic obstructive pulmonary disease (COPD) patients and their healthy spouses.

METHODS

Twenty-four-hour heart rate variability (HRV) and heart rate (HR) was measured in eight pairs of stable COPD patients and their healthy spouses. Real-time size-fractioned indoor PM and BC levels were monitored on the same, and preceding, days. Mixed-effects models were used to estimate the changes in health indices and pollutants after controlling for potential confounding variables.

RESULTS

Increases in size-fractioned PM and BC were associated with alterations in cardiac autonomic function in both COPD patients and their healthy spouses. However, the association patterns differed between the two groups. In COPD group, an IQR (13.65 μg/m³) increase in PM_0.5 at 12-h moving average was associated with reductions of 14.62% (95% CI: -21.74%, -6.86%) in total power (TP) and 10.14% (95% CI: -16.11%, -3.76%) in high frequency (HF) power. In healthy volunteers, however, TP and HF declined immediately upon exposure to PM and then returned to normal levels gradually. In this group, an IQR increase in PM_0.5 at 5 min moving average was associated a 20.30% (95% CI: -25.49%, -14.73%) reduction in TP and a 31.79% (95% CI: -36.48%, -26.72%) reduction in HF.

CONCLUSIONS

Exposure to indoor PM and BC was associated with cardiac autonomic dysfunction in COPD patients and their healthy spouses. Exposure had a greater lagged effect on HRV in COPD patients than in healthy participants. These findings will aid the formulation of targeted measures to prevent the adverse effects of indoor air pollution for individuals with different health statuses.

The short-term effects of indoor size-fractioned particulate matter and black carbon on cardiac autonomic function in COPD patients

BACKGROUND

Previous studies have reported adverse health effects of indoor air pollutants especially particulate matter (PM) and black carbon (BC). Patients with chronic obstructive pulmonary disease (COPD) have been shown to be more likely with cardiovascular comorbidities in which cardiac autonomic dysfunction plays an important role. However, there is little evidence for the effect of indoor PM and BC exposures on cardiac autonomic function in COPD patients.

OBJECTIVES

To evaluate the association between exposure to indoor size-fractioned PM and BC and changes in HRV and HR in COPD patients.

METHODS

Forty-three doctor diagnosed, stable COPD patients were recruited and measured for 24-h HRV and HR. Real-time indoor size-fractioned PM and BC were monitored on the day before and the day of performing health measurements. Mixed-effects models were used to estimate the associations between indoor PM and BC and HRV indices and HR after controlling for potential confounders.

RESULTS

Increasing levels of size-fractioned PM and BC were associated with decreased HRV indices and increased HR. An IQR (3.14μg/m³) increase in 8-h BC moving average and an IQR (20.72μg/m³) increase in 5-min PM_0.5 moving average concentrations were associated with declines of 7.45% (95% CI: -10.89%, -3.88%) and 16.40% (95% CI: -21.06%, -11.41%) in LF, respectively. The smaller the particles size, the greater effects on HRV indices and HR. Patients' BMI modified the associations between size-fractioned PM and BC and their HRV and HR. For an IQR increase in PM_0.5, there was decline in HF of 34.85% (95% CI: -39.08%, -30.33%) in overweight patients, compared to a 2.01% (95% CI: -6.44%, 11.19%) increase in normal-weight patients.

CONCLUSIONS

Exposures to indoor PM and BC were associated with altered cardiac autonomic function in COPD patients, and the associations for HRV measures of parasympathetic activity (e.g., HF) were more apparent in overweight patients.

Blunted heart rate recovery is associated with coronary artery spasm in patients with suspected vasospastic angina

Background

Autonomic nervous system activity has been shown to be altered in patients with vasospastic angina (VA). Heart rate recovery (HRR) is a simple, non-invasive measurement of autonomic nervous system dysfunction. We aimed to investigate whether HRR is related to VA, as established by an ergonovine test.

Methods

A total of 976 consecutive patients (47.5% male, mean age 55 years) without significant coronary artery disease who underwent both an ergonovine provocation test and a treadmill exercise test were enrolled. The relationship between VA and HRR was evaluated.

Results

A total of 30.7% (300/976) of patients were diagnosed with VA, as documented by the ergonovine provocation test. HRR was significantly reduced in patients with VA compared to patients without VA (24.6 ± 18.0 vs. 30.5 ± 22.2, p < 0.001), and HRR was lowest in patients with multi-vessel spasm (21.9 ± 17.3). The proportion of blunted HRR, which was defined as HRR less than 12 beats, was significantly higher in patients with VA than in those without coronary artery spasm (26.6% vs. 39.3%, p < 0.001). In multivariable regression analyses, age (odds ratio (OR) = 1.03; 95% confidence interval (CI): 1.01–1.04; p = 0.001), blunted HRR (OR = 1.71; 95% CI: 1.26–2.31; p < 0.001), current smoking status (OR = 2.11; 95% CI: 1.50–2.98; p < 0.001), and male gender (OR = 2.00; 95% CI: 1.43–2.78; p < 0.001) were significant independent predictors of VA presence.

Conclusion

Blunted HRR was an independent predictor of VA presence, which suggests a link between coronary artery spasm and autonomic dysregulation.

The relationships of current suicidal ideation with inflammatory markers and heart rate variability in unmedicated patients with major depressive disorder

Studies investigating inflammatory status and autonomic functioning simultaneously in depressed patients with current suicidal ideation (SI) are lacking. We recruited 58 unmedicated depressed patients with current SI but without lifetime history of suicidal behavior, as well as 61 equally depressed patients without lifetime history of SI or suicidal behavior. We measured serum cortisol, high-sensitivity C-reactive protein (hs-CRP), erythrocyte sedimentation rate (ESR), and autonomic functioning evaluated by frequency-domain measures of heart rate variability (HRV). The intensity of current SI was rated with the Columbia Suicide Severity Rating Scale. Chronic psychological stress was assessed using the Chinese version of the Perceived Stress Scale (PSS). Patients with current SI showed higher hs-CRP and ESR but lower variance (total HRV), low frequency (LF), and high frequency (HF) HRV than those without lifetime history of SI. We found no differences in cortisol levels and PSS scores. The intensity of current SI was negatively correlated with variance, LF, and HF but positively correlated with hs-CRP. Our results help improve the understanding of the relationships among current SI, inflammation, and autonomic functioning in depressed patients. The combined use of inflammatory markers and HRV indices may one day be applied in predicting and monitoring patients' suicide risk.

Epicardial Fat Thickness is Correlated with Vagal Hyperactivity in Patients with Neurally-Mediated Syncope

BACKGROUND

Epicardial fat tissue has unique endocrine and paracrine functions that affect the cardiac autonomic system. The head-up tilt test (HUTT) is a simple non-invasive measurement that assesses autonomic nervous system dysfunction. We investigated the association between epicardial fat thickness (EFT) and autonomic neural tone, such as vagal tone.

METHODS

A total of 797 consecutive patients (mean age 46.5 years, male: 45.7%) who underwent HUTT and echocardiography between March 2006 and June 2015 were enrolled. EFT was measured during the diastolic phase of the parasternal long axis view. We excluded patients with prior percutaneous coronary intervention, old age (* 70 years old), valvular heart disease, symptomatic arrhythmias and diabetes. We divided patients into two groups based on the HUTT (positive vs. negative).

RESULTS

There were 329 patients (41.3%) with a negative HUTT result and 468 patients (58.7%) with a positive result. The HUTT-positive patients showed a significantly lower waist circumference, body mass index and systolic and diastolic blood pressure, although a significantly higher EFT as compared to the HUTT-negative patients (HUTT-positive, 5.69 ± 1.76 mm vs. HUTT-negative, 5.24 ± 1.60 mm; p < 0.001). EFT > 5.4 mm was associated with a positive HUTT result with 51.7% sensitivity and 63.8% specificity (p < 0.001) on receiving operator characteristic analysis. Multivariate Cox regression analysis revealed that EFT (hazard ratio: 1.02, 95% confidence interval: 1.01-1.30, p = 0.004) was an independent predictor of HUTT-positivity.

CONCLSION

EFT was significantly correlated with positive HUTT, which suggests an association between EFT and autonomic dysregulation.

Identifying high-risk post-infarction patients by autonomic testing - Below the tip of the iceberg

Despite major advances in medical therapies late mortality after myocardial infarction (MI) is still high. A substantial proportion of post-MI patients die from sudden cardiac death. Prophylactic implantable-cardioverter defibrillator (ICD) therapy has been established for post-MI patients with reduced left ventricular ejection fraction (LVEF ≤35%). However, most patients who die after MI have an LVEF >35%. For this large group of patients, no specific prophylactic strategies exist. There is strong evidence that measures of cardiac autonomic dysfunction after MI provide important prognostic information in post-MI patients with preserved LVEF. Combinations of autonomic markers can identify high-risk patients after MI with LVEF >35% whose prognosis is equally worse than that of patients with LVEF ≤35%. The ongoing REFINE-ICD (NCT00673842) and SMART-MI trials (NCT02594488) test different preventive strategies in high-risk post-MI patients with cardiac autonomic dysfunction and LVEF 36-50%. While REFINE-ICD follows the traditional concept of ICD-implantation, SMART-MI uses implantable cardiac monitors with remote monitoring capabilities to sensitively detect asymptomatic, but prognostically relevant arrhythmias that could trigger specific diagnostic and therapeutic interventions.

The effect of marine n-3 polyunsaturated fatty acids on cardiac autonomic and hemodynamic function in patients with psoriatic arthritis: a randomised, double-blind, placebo-controlled trial

BACKGROUND

The aim of this study was to investigate the effect of marine n-3 polyunsaturated fatty acids (PUFA) on cardiac autonomic function and vascular function in patients with psoriatic arthritis.

METHODS

The study was conducted as a randomized, double-blind, placebo-controlled trial, where 145 patients with psoriatic arthritis were supplemented with 3 g of n-3 PUFA or olive oil (control) daily for 24 weeks. Blood pressure, heart rate, heart rate variability (HRV), central blood pressure, pulse wave velocity (PWV) and fatty acid composition of granulocytes, were determined at baseline and after supplementation.

RESULTS

At baseline we found a significant difference in the mean of all normal RR intervals (inverse of heart rate, vary from beat to beat) when comparing subjects with the highest vs the lowest fish intake (p = 0.03). After supplementation for 24 weeks there was a trend towards an increase in RR (p = 0.13) and decrease in heart rate (p = 0.12) comparing the n-3 PUFA group with the control group. However, per-protocol analysis showed significantly increased RR (p = 0.01) and lowered heart rate (p = 0.01) in the n-3 PUFA supplemented patients compared with controls. Blood pressure, PWV and Central blood pressure did not change after supplementation with n-3 PUFA. Adjustment for disease activity and conventional cardiovascular risk factors did not change the results.

CONCLUSIONS

Marine n-3 PUFA increased RR intervals in patients with psoriatic arthritis which may suggest a protective effect of n-3 PUFA against cardiovascular disease in this population.

TRIAL REGISTRATION

Clinicaltrials.gov Identifier: NCT01818804.

Timing of obstetrical assistance affects peripartal cardiac autonomic function and early maternal behavior of dairy cows

Peripartal autonomic nervous system function and early maternal behavior were investigated in 79 multiparous Holstein-Friesian cows. Animals were allocated into four groups based on the technology of calving management: 1) unassisted calving in a group pen (UCG; N=19), 2) unassisted calving in an individual pen (UCI; N=21), 3) assisted calving with appropriately timed obstetrical assistance (ACA; N=20), and 4) assisted calving with premature obstetrical assistance (ACP; N=19). Heart rate, the high frequency (HF) component of heart rate variability (HRV) as a measure of vagal activity and the ratio between the low frequency (LF) and HF components (LF/HF ratio) as a parameter of sympathetic nervous system activity were calculated. Heart rate and HRV parameters were presented as areas under the curves (AUC) for the following periods: 1) prepartum period (between 96h before the onset of calving restlessness and the onset of restlessness), 2) parturition (between the onset calving restlessness and delivery), and 3) postpartum period (during a 48-h period after delivery). Pain-related behaviors were recorded during parturition (i.e., the occurrence of vocalization and stretching the neck towards the abdomen) and during a 2-h observation period after calving (i.e., the occurrence of vocalization, stretching the neck towards the abdomen and the duration of standing with an arched back). Early maternal behavior was observed during the first 2h following calving as follows: 1) latency and duration of sniffing calf's head/body, and 2) latency and duration of licking calf's head/body. No difference was found across groups in autonomic function before the onset of calving restlessness. Area under the heart rate curve was higher in ACP cows during parturition (39.6±2.5beats/min×h) compared to UCG, UCI and ACA animals (AUC=13.1±0.9beats/min×h, AUC=22.3±1.4beats/min×h and AUC=25.0±2.1beats/min×h, respectively). Area under the heart rate curve did not differ across the UCG, UCI and ACA groups during the postpartum period (AUC=65.2±16.7beats/min×h, AUC=58.0±14.2beats/min×h and AUC=62.9±12.1beats/min×h, respectively) but it was higher in ACP cows compared to the former groups (AUC=269.1±36.3beats/min×h). During parturition, area under the HF curve reflected a lower vagal tone (AUC=-30.5±1.6n.u.×h) in cows with premature obstetrical assistance than in animals that calved individually without farmer assistance (AUC=2.7±0.4n.u.×h) or with appropriately timed assistance (AUC=3.2±1.2n.u.×h). During parturition, LF/HF ratio showed greater sympathetic activity in ACP cows than in animals from any other group. Area under the HF curve was similar across UCG, UCI and ACA cows (AUC=-232.1±42.0n.u.×h, AUC=-163.4±35.6n.u.×h and AUC=-331.4±56.2n.u.×h, respectively) during the postpartum period and was the lowest in ACP cows (AUC=-1025.6±44.2n.u.×h) reflecting a long-term stress load in the latter group. During parturition, both vocalization and stretching the neck towards the abdomen occurred more often in UCG cows than in cows from any other groups, and the incidence of both behaviors was statistically higher in ACP cows than in UCI and ACA animals. There were no significant differences across groups in these behaviors during the 2-h postpartum observation. UCG cows had a shorter latency and a longer duration of maternal grooming during the first 2h following delivery compared to any other groups. UCI and ACA dams spent more time with licking the calf within the 2-h period after calving and had a shorter latency to sniff and lick the offspring compared to cows that received premature assistance. Group calving is less stressful for cows than calving in an individual pen either with or without obstetrical assistance. Calving in a group or with appropriately timed farmer assistance supports the expression of early maternal behavior and lead to a rapid postpartum recovery of the autonomic nervous system. Premature obstetrical assistance means stress for cows during parturition, leads to a prolonged postpartum recovery of the autonomic nervous system and inhibits the expression of early maternal behavior.

Heart rate variability to differentiate essential tremor from early-stage tremor-dominant Parkinson's disease

BACKGROUND

Essential tremor (ET) and Parkinson's disease (PD) are the most common movement disorders in the elderly, but it is difficult to differentiate ET from early-stage tremor-dominant Parkinson's disease (TDPD).

METHODS

We investigated heart rate variability (HRV) in 23 patients with ET, 27 patients with TDPD, and 23 healthy controls. HRV was determined using the RR intervals of a 5-min electrocardiogram recording. Measurements of beat-to-beat RR variability, including time domains [(standard deviation of the normal-to-normal RR interval (SDNN), and the root mean square difference of successive RR intervals (RMSSD)] and frequency domains [low-frequency (LF) and high-frequency (HF) components and total spectral power (TP)], were assessed retrospectively.x

RESULTS

In the TDPD group, SDNN, LF, HF, and TP were significantly lower than those in the ET group. In a receiver operating characteristic area under the curve (AUC) analysis, LF was the best potential diagnostic marker (AUC=0.87).

CONCLUSION

Non-invasive and routine electrocardiography may be helpful in differentiating ET from TDPD during the early disease stage.

Association among epicardial fat, heart rate recovery and circadian blood pressure variability in patients with hypertension

Background

Epicardial fat tissue is known to have an unique endocrine function which affect the cardiac autonomic system. Heart rate recovery (HRR) is a simple non-invasive measurement that assesses autonomic nervous system dysfunction. We aimed to investigate the association among epicardial fat thickness (EFT), HRR and circadian blood pressure (BP) variation in patients with hypertension.

Methods

A total of 358 consecutive patients who underwent both 24-hour ambulatory BP monitoring (ABPM) and a treadmill test were enrolled. Echocardiographic EFT and HRR, defined as peak heart rate minus heart rate after a 1-min recovery time, were measured. Patients were classified according to the ABPM; 147 patients with hypertension with a dipping pattern at night (dippers), 140 patients with hypertension with a non-dipping pattern at night (non-dippers) and 71 normotensive controls.

Results

EFT was significantly higher in hypertensive patients, especially in the non-dipper group, compared to the controls (non-dippers, 7.5 ± 2.9 mm; dippers, 6.6 ± 1.6 mm; controls, 5.5 ± 2.1 mm; p < 0.001). HRR was significantly lower in both hypertensive groups as compared to the control group and was the lowest in the non-dipper group (non-dipper, 26.6 ± 18.6; dipper, 29.5 ± 21.5; control, 71.4 ± 19.8; p < 0.001). EFT was significantly correlated with age, body mass index, 24-hour mean systolic BP and 24 h mean BP variability, whereas exercise duration, metabolic equivalents (METs) and HRR were inversely correlated with EFT. Furthermore, EFT > 6.7 mm was associated with a blunted HRR with 76 % sensitivity and 61 % specificity (ROC area under curve: 0.71, 95 % confidence interval, CI = 0.65–0.76, p < 0.001). In a multivariate analysis, EFT (odds ratio, OR = 3.53, 95 % CI = 1.20–10.37, p = 0.022) and 24-hour mean BP variability (OR = 1.09, 95 % CI = 1.03–1.16, p = 0.005) were independent predictors of a blunted HRR defined as HRR ≤ 12 beats (n = 63) in patients with hypertension.

Conclusion

EFT and HRR were significantly correlated with circadian BP variability in patients with hypertension. EFT and circadian BP variability were independent predictors of blunted HRR, which suggests a link between epicardial fat and autonomic dysregulation in hypertension.

Heart rate variability in major depressive disorder and after antidepressant treatment with agomelatine and paroxetine: Findings from the Taiwan Study of Depression and Anxiety (TAISDA)

Evidence from previous studies suggests that heart rate variability (HRV) is reduced in major depressive disorder (MDD). However, whether this reduction is attributable to the disorder per se or to medication, since antidepressants may also affect HRV, is still debated. There is a dearth of information regarding the effects of agomelatine, a novel antidepressant, on HRV. Here, we investigated whether HRV is reduced in MDD and compared the effects of agomelatine and paroxetine on HRV. We recruited 618 physically healthy unmedicated patients with MDD and 506 healthy volunteers aged 20-65 years. Frequency-domain measures of resting HRV were obtained at the time of enrollment for all participants. For patients with MDD, these measures were obtained again after 6 weeks of either agomelatine or paroxetine monotherapy. Compared with healthy subjects, unmedicated patients with MDD exhibited significantly lower variance (total HRV), low frequency (LF), and high frequency (HF) HRV, and a higher LF/HF ratio. Depression severity independently contributed to decreased HRV and vagal tone. Fifty-six patients completed the open-label trial (n=29 for agomelatine, n=27 for paroxetine). Between-group analyses showed a significant group-by-time interaction for LF-HRV and HF-HRV, driven by increases in LF-HRV and HF-HRV only after agomelatine treatment. Within the paroxetine-treated group, there were no significant changes in mean R-R intervals or any HRV indices. We therefore concluded that MDD is associated with reduced HRV, which is inversely related to depression severity. Compared with paroxetine, agomelatine has a more vagotonic effect, suggesting greater cardiovascular safety. Clinicians should consider HRV effects while selecting antidepressants especially for depressed patients who already have decreased cardiac vagal tone.

Comparison of effects of OSA treatment by MAD and by CPAP on cardiac autonomic function during daytime

PURPOSE

The present study compared the effects of mandibular advancement therapy (MAD) with continuous positive airway pressure therapy (CPAP) on daytime cardiac autonomic modulation in a wide range of obstructive sleep apnea (OSA) patients under controlled conditions in a randomized, two-period crossover trial.

METHODS

Forty OSA patients underwent treatment with MAD and with CPAP for 12 weeks each. At baseline and after each treatment period, patients were assessed by polysomnography as well as by a daytime cardiac autonomic function test that measured heart rate variability (HRV), continuous blood pressure (BP), and baroreceptor sensitivity (BRS) under conditions of spontaneous breathing, with breathing at 6, 12, and 15/min.

RESULTS

Both CPAP and MAD therapy substantially eliminated apneas and hypopneas. CPAP had a greater effect. During daytime with all four conditions of controlled breathing, three-minute mean values of continuous diastolic BP were significantly reduced for both MAD and CPAP therapy. At the same time, selective increases due to therapy with MAD were found for HRV high frequency (HF) values. No changes were observed for BRS in either therapy mode.

CONCLUSIONS

These findings indicate that both MAD and CPAP result in similar beneficial changes in cardiac autonomic function during daytime, especially in blood pressure. CPAP is more effective than MAD in eliminating respiratory events.

Heart Rate Variability in Adolescents - Normative Data Stratified by Sex and Physical Activity

BACKGROUND

Heart rate variability (HRV) refers to the beat-to-beat fluctuations in the cardiac rhythm occurring due to modulation of the pacemaker (sinoatrial node) activity of the heart by the sympathetic and parasympathetic branches of the autonomic nervous system. Nowadays, cardiovascular diseases and their risk factors are increasingly occurring at a younger age (children and adolescents) and recording of HRV in them will help us to identify cardiovascular autonomic derangement earlier. However, to be used clinically, normative data has to be established in this age group considering other major factors that can influence HRV such as sex, physical activity, and BMI.

MATERIALS AND METHODS

Task Force of the European Society of Cardiology and the North American Society of Pacing and Electrophysiology has provided the standards for measurement of heart rate variability and we have followed the same. In the present study, we have described the normative data for HRV in the adolescent in the age group of 12-17 years, stratified based on sex and physical activity.

RESULTS

Data given below are expressed as median with interquartile range (Median (IQR)) in the following order: non-athlete girls, non athlete boys, athlete girls and athlete boys. Time domain indices - SDNN - 66.35 (40.78), 63.20 (36.20), 113.00 (31.40) and 94.20 (35.55); RMSSD - 69.00 (50.55), 58.70 (43.40), 94.90 (42.10) and 100.30 (47.50); NN50 - 137.50 (100.25), 116.00 (90.50), 137.00 (81.00) and 156.00 (81.50). The frequency domain indices - LF power 1015.00 (1098.75), 945.00 (831.00), 1465 (642.25), and 1211.00 (811.37); HF power - 1324.00 (1707.00), 988.00 (1426.50), 2409.00 (1387.50), and 2219.00 (1752.00); Total power - 3374.50 (3094.25), 2757.00 (2641.00), 5202.00 (2501.50) and 5273.00 (3507.50); LFnu - 45.44 (16.61), 47.63 (29.98), 38.59 (11.81) and 37.10 (11.21); HFnu - 54.56 (16.61), 52.37 (29.98), 61.41 (11.81) and 62.90 (11.21).

CONCLUSION

We have given sex and physical activity stratified HRV normative data for adolescents in the age between 12-17 years.

Postexercise autonomic function after repeated-sprints training

PURPOSE

We examined the effects of an 8-week repeated-sprint (RS) training protocol on postexercise parasympathetic reactivation (PNSr) in healthy adults.

METHODS

Eighteen male adults (24.3 ± 3.7 years) were assigned to either of two groups. One group (n = 9) performed RS training (EXP, 3 times week(-1), 18 maximal all-out 15-m sprints interspersed with 17 s of passive recovery); the other served as the control group (CON, n = 9). Performance before, during, and after was assessed by measuring RS ability time (S dec) and total sprint time. The subjects were then seated for 10 min immediately after each trial and postexercise HR recovery (HRR), and vagal-related HR variability (HRV) indices were measured.

RESULTS

All subjects demonstrated a decrease in S dec. However, only EXP showed a decrease in total sprint time (-10.5 % of baseline value). Using a qualitative statistical analysis method, we found a likely to almost certain positive effect of RS training on HR. The mean of each HRR and HRV index indicated a greater change in PNSr in EXP than in CON (e.g. with a 78/22/1 % chance to demonstrate a positive/trivial/negative effect on HRR60s after RS training; 74/21/5 % on LN rMSSD5-10min). Large correlations were noted between the changes in S dec [r = 0.59, 90 % CI (0.43)], total sprint time [r = -0.61 (0.42)] and HRR60s.

CONCLUSION

RS training seems to be an effective method to improve postexercise PNSr in healthy adults. Also, HRR60s appears to be a method for evaluating positive adaption to RS training.

Heart rate turbulence for predicting new-onset atrial fibrillation in patients undergoing coronary artery bypass grafting

BACKGROUND

Cardiac autonomic dysfunction reportedly contributes to the AF triggering and maintenance. Heart rate turbulence (HRT) is a promising noninvasive measure of cardiac autonomic function. We investigated whether ambulatory ECG-based HRT measurement could predict in-hospital new-onset atrial fibrillation (AF) after coronary artery bypass graft (CABG) surgery.

METHODS

HRT onset (TO) and slope (TO) were prospectively measured from 24-h Holter recording in 113 consecutive patients prior to CABG. Abnormal HRT was defined as at least one abnormal value in TO (> 0%) and TS (< 2.5 ms/RR).

RESULTS

Patients with abnormal HRT (n = 60) showed a significantly higher AF incidence (47% versus 21%, P = 0.005) and AF burden (29 ± 9 versus 7 ± 5 h, P = 0.043) than those with normal HRT (n = 53). Abnormal HRT were identified as independent predictors for the new-onset postoperative AF. During the follow-up period (12.0 ± 10.5 months), the abnormal HRT group showed a worse prognosis versus the normal HRT group regarding the AF recurrence/postoperative stroke (P = 0.018). Additionally, the postoperative AF incidence, in-hospital AF burden, and the rate of AF recurrence/postoperative stroke gradually elevated as the number of abnormal HRT values increased from 0 to 2.

CONCLUSIONS

Preoperative abnormal HRT was significantly associated with worse short-term (in-hospital new-onset AF) and long-term outcomes (post-discharge AF recurrence/postoperative stroke) after CABG surgery. Additional studies incorporating preventive interventions depending on the preoperative HRT results might be worthwhile in this patient group.

Cardiac autonomic function and insulin resistance for the development of hypertension: a six-year epidemiological follow-up study

BACKGROUND AND AIMS

To explore the impact of cardiac autonomic function (CAF) and insulin resistance (IR) on incident hypertension.

METHODS AND RESULTS

In 1996, 1638 subjects finished baseline examination, which included anthropometry, blood pressures, CAF, blood biochemistry, plasma insulin, urine examination and electrocardiogram. CAF included standard deviation of normal-to-normal intervals or RR intervals (SDNN), low- and high-frequency power spectrum (LF and HF), and LF/HF ratio at supine for 5 min, the RR interval changes during lying-to-standing maneuver, and the ratio between the longest RR interval during expiration and the shortest RR interval during inspiration (E/I ratio). We used homeostasis model assessment to define beta cell function (HOMA-B) and insulin resistance (HOMA-IR). In total, 992 non-hypertensive participants completed the follow-up assessment in 2003 and 959 participants were included for the final analysis. Incident hypertension was determined by blood pressure status at follow-up. In unadjusted model, both square root of HOMA-IR (OR:3.37, 95%CI: 2.10-6.64) and HOMA-B (OR:0.996, 95%CI: 0.992-0.999) were related to incident hypertension. In multivariate model, square root of HOMA-IR (OR:1.97, 95%CI: 1.05-3.70), but not HOMA-B, was associated with incident hypertension. After further adjustment for baseline CAF, the positive relationship between the square root of HOMA-IR and incident hypertension disappeared. In contrast, LF/HF ratio (OR:1.18, 95%CI: 1.01-1.37), HF power (OR:0.98, 95%CI: 0.96-0.999), and E/I ratio (OR:0.71, 95%CI: 0.54-0.95) were each independently associated with incident hypertension after further adjustment for HOMA measures.

CONCLUSION

Sympathovagal imbalance with an apparently decreased parasympathetic tone is an important predictor of incident hypertension independent of IR.

Generalized anxiety disorder, comorbid major depression and heart rate variability: a case-control study in taiwan

OBJECTIVE

Decreased heart rate variability (HRV) has been reported in generalized anxiety disorder (GAD), but the results are mixed. Little is known about the impact of comorbid major depression (MD) on HRV in GAD patients. Both issues necessitate further investigation.

METHODS

Twenty unmedicated, physically healthy GAD patients, 20 GAD patients with a secondary diagnosis of MD, 40 MD patients and 60 matched controls were recruited. We used the Hamilton Anxiety Rating Scale and the Hamilton Depression Rating Scale to assess anxiety and depression severity, respectively. Cardiac autonomic function was evaluated by measuring HRV parameters. Frequency-domain indices of HRV were obtained.

RESULTS

Three patient groups had more anxiety and depression symptoms than control subjects, but heart rates (HRs) were significantly elevated only in GAD patients with comorbid depression. Relative to controls, GAD patients had reduced HRV while GAD patients with comorbid depression displayed the greatest reductions in HRV among three patients groups. Correlation analyses revealed anxiety/depression severity significantly associated with HRs, variance, LF-HRV and HF-HRV. However, separately analyzing among individual groups and adjusting for HRV-associated covariables rendered the correlations non-significant.

CONCLUSION

Our results suggest that reduction in HRV is a psychophysiological marker of GAD and individuals with comorbid GAD and MD may be distinguished based on psychophysiological correlates (for example, HF-HRV) from non-comorbid GAD patients. Taken into account that comorbid depression may confer increased risks for cardiovascular events in GAD patients, this subgroup of GAD patients may benefit better from cardiovascular risk reduction strategies.

Decreased cardiac vagal control in drug-naïve patients with posttraumatic stress disorder

OBJECTIVE

Decreased cardiac vagal control (CVC) has been proposed in posttraumatic stress disorder (PTSD), but the results are mixed. Analyses with larger sample sizes and better methodology are needed.

METHODS

Thirty-two drug-naïve survivors with current PTSD, 32 survivors without PTSD and 192 matched controls were recruited for a case-control analysis. We used the PTSD checklist-civilian version (PCL-C) to assess posttraumatic symptoms severity. Cardiac autonomic function was evaluated by measuring heart rate variability (HRV) parameters. Frequency-domain indices of HRV were obtained. The obtained results were evaluated in association with personality traits assessed by the Tridimensional Personality Questionnaire (TPQ).

RESULTS

PTSD patients exhibited decreased LF-HRV and HF-HRV as compared to survivors without PTSD and to matched controls. The PTSD symptoms severity was associated with reduced mean RR intervals, Var-HRV, LF-HRV and HF-HRV. The harm avoidance score (which has been suggested to be associated with serotonergic activity) was negatively correlated with Var-HRV, LF-HRV and HF-HRV.

CONCLUSION

These data suggest that PTSD is accompanied by decreased CVC, highlighting the importance of assessing HRV in PTSD patients. In view of the increased risk for cardiovascular diseases in these vulnerable individuals, one might consider the treatment to restore their autonomic function while reducing PTSD symptoms.