Decreased Heart Rate Variability Research Articles

A Descriptive Research of Decreased Heart Rate Variability as a Risk Factor for Cardiovascular Disease in Young, Healthy Adults with Low and High BMI Indexes

Background and objectives: HRV is used to evaluate autonomic nervous system input to the heart. Several studies have examined the effect of HRV on underweight status. To assess HRV in age-matched young people with varying BMI categories. Methods: This cross-sectional study was conducted on healthy young adults between the ages of 18 and 25. Variables of anthropometrics were measured. ECG was recorded for 5 minutes in lead II setup. Kubios HRV analyzer was used to evaluate heart rate variability. Results: HRV indices were lower in the underweight, overweight, and obese BMI groups compared to the normal weight group. Both genders exhibit an inverted U-shaped association between BMI and HF log power based on second-order polynomial regression. The correlation between BMI, waist circumference, and body fat (%) and HRV indices demonstrates a substantial relationship with heart rate variability, with waist circumference (WC) exhibiting a stronger relationship than BMI. Comparing HRV parameters between men and women of different BMI groups reveals that women exhibited more heart rate variability than men across BMI groups. Conclusion: Underweight individuals share the same elevated cardiovascular risk as the obese, and abdominal obesity is a more accurate predictor of cardiovascular risk than the body mass index (BMI).

Abstract P2079: Heart Rate Variability And Chronotropic Incompetence As Prognostic Markers In A Preclinical Model Of HFpEF

The prevalence of heart failure with preserved ejection fraction (HFpEF) in developed countries is increasing alarmingly. This is in part due to an increase in comorbid diseases (obesity, diabetes, hypertension), and risk factors (age, stress, and low physical activity). HFpEF patients often present with chronotropic incompetence (CI) and impaired heart rate variability (HRV), and both CI and decreased HRV are used as prognostic markers of heart disease and sudden cardiac death in clinical studies. In preclinical HFpEF models, however, CI and HRV are not commonly evaluated, and the efficacy of novel compounds is determined primarily through echocardiography results. Thus, there is a need to align efficacy readouts to enhance the translatability of novel compounds from preclinical to clinical stages. Here we sought to determine the utility of CI and HRV in preclinical HFpEF studies in a novel 2-hit HFpEF model; the metabolic syndrome non-alcoholic steatohepatitis mouse with AAV overexpression of renin (MS-NASH+Renin). To collect continuous and conscious electrocardiogram and blood pressure data, C57BL/6 (n=10) and MS-NASH (formerly FATZO, n=32) male mice were implanted with radiotelemeters at 20 weeks and iv injected with either AAV-Vector or AAV-Renin. To assess disease burden, CI and HRV, we acquired and analyzed body weight, electrocardiography, peak VO2, exercise HR, and echocardiography data once a month for 5 months. We found that MS-NASH mice have increased body weight regardless of treatment, and that renin treatment increased blood pressure for both C57BL/6 and MS-NASH mice. Peak VO2, time to exhaustion, distance traveled, and maximum and recovery HR are significantly decreased in MS-NASH mice, indicating CI. HRV is also significantly decreased in MS-NASH mice when compared to C57BL/6. Interestingly, renin treatment did not further decrease treadmill performance or HRV for MS-NASH mice. However, MS-NASH+Renin mice did have decreased functional capacity with preserved ejection fraction and altered heart structure. These results suggest that MS-NASH+Renin is a model for HFpEF, and that CI and HRV are translatable markers for HFpEF. In the future, we will evaluate the use of CI and HRV in preclinical HFpEF drug development studies.

488-P: Subclinical Autonomic Neuropathy in Uncomplicated Type 2 Diabetes

Cardiac autonomic neuropathy (CAN), a common complication of type 2 diabetes (T2D), is often not detected until late in disease progression. Autonomic nervous system (ANS) dysfunction impairs control of heart rate (HR) and vascular dynamics, manifesting as decreased HR variability (HRV) and impaired blood pressure (BP) regulation. We hypothesized that ANS function is impaired in participants with uncomplicated T2D and correlates with cardiac measures. We measured HRV during cycled breathing and Valsalva and postural HR and BP on overweight physically inactive adults aged 22-70 years with (N=53) and without (N=56) T2D. HRV with cycled breathing and Valsalva was lower in participants with T2D (p=0.007 and 0.005, respectively). HRV with respiration was lower with age >50 years (p=0.0001). HRV with respiration correlated with increased age in T2D but not in overweight control participants. There were no significant changes in postural BP or HR with age >50 years or T2D. Significant correlations between ANS measures and cardiac function were only seen in those with T2D. Valsalva ratio was positively correlated with end-diastolic volume (Pearson’s r 0.58, p=0.02) and stroke volume (Pearson’s r 0.55, p=0.03). HRV with respiration was positively correlated with longitudinal, diastolic peak strain rate (SR) (Pearson’s r 0.68, p=0.007). Postural BP was positively correlated with circumferential and longitudinal, systolic peak SR (Pearson’s r =0.45 and 0.48 and p-value=0.05 and 0.04, respectively) and negatively correlated with radial and circumferential peak strain (Pearson’s r =-0.49 and -0.48 and p-value=0.03 and 0.03, respectively). These data suggest subclinical CAN associated with cardiac dysfunction is present in people with otherwise uncomplicated T2D and is exacerbated with age. Detecting CAN changes early may identify people at risk for cardiac disease and inform targeted intervention to restore cardiometabolic health in people with T2D. Disclosure A.Johnston: None. L.A.Abushamat: None. D.Enge: None. A.J.Barker: None. E.W.Clark: None. D.Rafferty: None. J.G.Regensteiner: None. J.E.B.Reusch: Advisory Panel; Medtronic. Funding American Diabetes Association (1-21-CMF-003 to L.A.A.); National Institutes of Health (T32DK120520-01A1); U.S. Department of Veterans Affairs (CX001532)

Menstrual cycle, heart rate variability (HRV), and mood: Is cyclicity of HRV associated with cyclicity of mood symptoms?

In an effort to understand potential biological indices of menstrually-related mood changes experienced by some naturally cycling individuals, we previously investigated whether vagally-mediated HRV (i.e., a biomarker of physical and mental health) fluctuates across the menstrual cycle. Our recent meta-analysis revealed a significant decrease of HRV in the midluteal phase which, as two-follow up studies suggest, is correlated with progesterone. However, the question remains whether cyclicity of HRV is associated with cyclicity of mood symptoms. Fifty naturally-cycling participants (M=24.8 years, SD=5.8) were examined (10-min baseline EKG for HRV assessment, PANAS for mood assessment) in three precisely determined cycle phases (ovulatory, midluteal, menstrual) via ovulation testing. To test the idea that degree of midluteal (vs. menstrual phase) HRV suppression is associated with the degree of PANAS same-day mood deterioration in the midluteal phase (vs. menstrual phase), each person’s difference score in HRV between the two phases was assessed. This between-person factor was taken into multilevel models predicting PANAS items from menstrual cycle phase. Analyses revealed that greater midluteal phase suppression of HRV was associated with greater midluteal phase increases in distress, as well as several fear and anxiety variables. No differences in sadness or irritability were found. These findings suggest that cyclical HRV suppression and cyclical increase in mood symptoms tend to covary. Further work is needed to clarify whether cyclicity of HRV may serve as a biological index of menstrually-related mood disorders.

Cardiovascular effects of wearing respirators against particulate matter: A randomized crossover trial

Fine particles (PM2.5) are implicated as an important risk to cardiovascular health. N95 respirators had been widely used to provide protection by filtering particles. Yet the practical effects of wearing respirators have not been fully understood. This study aimed to evaluate the cardiovascular effects of respirator wearing against PM2.5 and underpin the understanding of the mechanisms of cardiovascular responses triggered by PM2.5. We conducted a randomized, double-blind crossover trial among 52 healthy adults in Beijing, China. Participants were exposed to outdoor PM2.5 for 2 h in alterations wearing true respirators (with membranes) or sham ones (without membranes). We measured ambient PM2.5 and tested the filtration efficiency of the respirators. We compared the heart rate variability (HRV), blood pressure and arterial stiffness indicators between the true respirator group and the sham respirator group. Concentrations of ambient PM2.5 during the 2-h exposure ranged from 4.9 to 255.0 μg/m3. The filtration efficiency of true respirators was 90.1 % and that of sham ones was 18.7 %. Between-group differences varied by pollution levels. On less polluted days (PM2.5< 75 μg/m3), participants wearing true respirators showed lower levels of HRV and higher levels of heart rate compared with those wearing sham respirators. These between-group differences were inconspicuous on heavily polluted days (PM2.5≥ 75 μg/m3). We found that a 10 μg/m3 increase in PM2.5 was associated with a 2.2 % to 6.4 % decrease in HRV, prominent at 1 h after the start of exposure. N95 respirators have good performance in reducing PM2.5 exposure. Short-term exposure to PM2.5 can induce very acute responses in autonomic nervous function. However, the overall effects of wearing respirators might be not always favorable to human health in terms of their inherent adverse effects, which seem dependent on the levels of air pollution. Precise individual protection recommendations warrant to be developed.

Heart rate variability behavior in athletes after a sports concussion: A systematic review.

This systematic review aims to investigate the adaptations of the autonomic nervous system (ANS) after a concussion by measuring HRV in athletes over the age of 16 after injury. This systematic review followed the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA). Web of Science, Pubmed, SCOPUS, and Sport Discus were searched using predefined search terms to identify relevant original cross-sectional, longitudinal, and cohort epidemiological studies published before December 2021. After screening 1737 potential articles, four studies met the inclusion criteria. Studies included participants with concussion (n = 63) and healthy control athletes (n = 140) who practised different sports. Two studies describe a decrease in HRV following a sports concussion, and one proposed that the resolution of symptoms does not necessarily reflect ANS recovery. Lastly, one study concluded that submaximal exercise induces alteration in ANS, not seen in rest after an injury. In the frequency domain, a decrease in high frequency power and an increase of low frequency/high frequency ratio is expected, as the activity of the sympathetic nervous system increases, and the parasympathetic nervous system decreases after injury. In the frequency domain, heart rate variability (HRV) may help monitor the activity of ANS evaluating signals of somatic tissue distress and early identification of other types of musculoskeletal injuries. Further research should investigate the relationship between HRV and other musculoskeletal injuries.

Urinary phthalate metabolites and heart rate variability: A panel study

Phthalates exposure is linked with cardiovascular disease. Decreased heart rate variability (HRV) is an early indicator of cardiac autonomic imbalance. We conducted a longitudinal panel study in 127 Chinese adults with 3 repeated visits to explore the associations of individual and mixtures of phthalates exposure with HRV. We quantified 10 urinary phthalate metabolites by gas chromatograph-tandem mass spectrometer (GC-MS/MS) and 6 HRV indices by 3-channel digital Holter monitors. Linear mixed-effect (LME) models and Bayesian kernel machine regression (BKMR) models were separately implemented to evaluate the associations. After multivariate adjustments, we found that urinary mono-ethyl phthalate (MEP), mono-iso-butyl phthalate (MiBP), and mono-n-butyl phthalate (MBP) at lag 0 day were inversely associated with low-frequency power (LF) or total power (TP) (all P-FDR <0.05). In mixture analysis, we observed negative overall associations of phthalate mixtures at lag 0 day with LF or TP, and MiBP was the major contributor. Moreover, stratified analysis suggested that the inverse relationships of MiBP at lag 0 day with LF and TP were more prominent in subjects aged >50 years (all Pinteraction < 0.01). Our findings revealed that exposure to individual and mixtures of phthalates, especially MiBP, were related to decreased HRV.

Assessing the Sympathetic Response of Medical Doctors and Trainees when Exposed to a Virtual Realty Mass Casualty Incident Simulation

Introduction:The occurrence of disasters and mass casualty incidents (MCIs) is on the rise, thus training and rehearsal for disaster response remain paramount. Virtual reality (VR) platforms have previously been shown to be well-received, engaging, and immersive for disaster training. The primary objective of this study was to ascertain if a human actor-based VR MCI scenario could elicit a sympathetic response, as measured by heart rate variability (HRV), in medical doctors and trainees compared to a baseline state.Method:A simulation was filmed with students, residents, and surgeons on a GoPro 360 camera. Subjects (n=35) were recruited to sufficiently power (1-b=0.8) a Wilcoxon matched-pairs test and Welch’s t-test. Subjects watched the simulation on an Oculus Quest headset while having HRV recorded. Multivariate logistic regression was performed to identify factors associated with increased odds of significant sympathetic activation. Statistical significance was established at p&lt;0.05.Results:Thirty-five subjects were enrolled and included three trauma surgeons, three emergency medicine (EM) attendings, eight EM residents, six surgery residents, and 15 medical students. A significant decrease in HRV was observed across all groups in the MCI (median 20 ms IQR 16.2, 31.4 ms) compared to baseline (33.2 ms IQR 27.2, 44.1 ms; p&lt;0.0001). Sympathetic activation was most pronounced in students, then attendings, then residents. There was no significant difference in the fold-difference of sympathetic activation of EM physicians (-48.5% +/- 32.1%) versus surgeons (-49.5% +/- 25.2%; p=0.57). In all groups, SNS activation occurred independently of heart rate, age, sex, number of years in practice, first responder experience, or prior MCI response.Conclusion:Live-actor VR MCI simulation elicited a strong sympathetic response from students, residents, and attending physicians. By recruiting and disinhibiting essential neural pathways via controlled SNS activation, VR MCI training has the potential to enhance the encoding and consolidation of disaster training in a low-cost and reproducible manner.

PO-01-078 THE ACUTE PHYSIOLOGIC EFFECTS OF OSTEOPATHIC MANIPULATIVE TREATMENT IN PATIENTS WITH CARDIAC IMPLANTABLE ELECTRONIC DEVICES: A RANDOMIZED CONTROLLED TRIAL

Osteopathic manipulative treatment (OMT) is a procedure used to improve physiologic function and maintain homeostasis. OMT modulates the autonomic nervous system (ANS) and augments heart rate variability (HRV) in healthy subjects. The acute physiologic effects of OMT have been reported in patients with heart failure, but not in those with cardiac implantable electronic devices (CIEDs). To assess the short-term physiologic effects of OMT on heart rate, respiratory rate, arterial blood pressure, and HRV in patients with CIEDs. Cardiac patients with CIEDs at an osteopathic medical center were recruited into a randomized controlled trial (ClinicalTrials.gov ID: NCT0400474) and assigned to either OMT or light touch (control) groups. Short-term physiologic data was recorded pre and post intervention (including one minute HRV via photoplethysmography). HRV was calculated using root mean square of successive RR interval differences (RMSSD). Student’s t-test was used to compare groups; p < 0.05. 20 subjects were enrolled (10 OMT/10 control). Table 1 shows physiologic measurements prior to and post intervention. Changes in HR, RR, BP, and SpO2 were no different between groups before and after intervention; OMT HRV decreased by 12.39 + 34.05 ms, whereas control HRV increased by 19.94 + 18.54 ms (p=0.022). There was a significant decrease in HRV in the OMT group, but no difference in the remaining standard physiologic variables. The difference in HRV is opposite of what would be expected, and could be due to the effects of OMT on the ANS, altered cardiac response in this population, and possibly a decrease in ectopy. Further evaluation of CIED data (arrhythmias, HRV and activity level) may be helpful in determining the long-term effects of OMT on cardiac arrhythmia patients.

Chronic secondhand smoke exposure on cardiovascular regulation and the role of soluble epoxide hydrolase in mice

Background: Secondhand smoke (SHS) is a significant risk factor for cardiovascular morbidity and mortality. About 80% of SHS-related deaths are due to cardiovascular causes. Reducing SHS exposure with smoking bans is associated with improved cardiovascular outcomes in non-smokers. Soluble epoxide hydrolase (sEH) inhibitors have been shown to attenuate tobacco exposure-induced lung inflammatory responses, making them a great candidate for combating SHS exposure-induced cardiovascular outcomes. The goals of this study were to determine 1) the time course of environmentally relevant SHS exposure effects on cardiac autonomic function and blood pressure (BP) regulation and 2) whether prophylactic administration of a soluble epoxide hydrolase inhibitor (TPPU) can protect against SHS-induced autonomic and cardiovascular dysregulation. Methods: Male C57BL/6J mice (11 wk) implanted with BP/electrocardiogram (ECG) telemetry devices were exposed to 12 wks of either filtered air (FA, n=19) or 3 mg/m3 of SHS (6 hr/d, 5 d/wk, n=18), followed by 4 weeks recovery window (SHS substituted with FA). Separate mice were randomly assigned to one of the 3 groups: FA (n=12), FA+TPPU (n=12), and SHS+TPPU (n=22). TPPU (15 mg/l) was given by drinking water during the 12 weeks of exposure period (estimated dose = 3.75 ug/g/day). BP and ECG were recorded continuously for 36 hours every month when mice were not exposed. Data were stratified by 12-hour circadian window: The dark cycle (dark 1) immediately after the 5th day of exposure and the following light and dark (dark 2) cycles. Baroreflex sensitivity (BRS) was determined with the sequence method. Standard time domain heart rate variability (HRV) parameters were obtained from normal-to-normal R-R intervals. Results: SHS-exposed mice had significantly higher physical activity levels (~ 50% higher, p&lt;0.05), an effect that persisted 4 wks after cessation of SHS exposure. SHS exposure significantly decreased 1) short-term HRV (RMSSD) by ~20% as early as after 4 wks of exposure; 2) overall HRV (SDNN) with maximum effect at 12 wks (-15%, p&lt;0.05); 3) pulse pressure (-8%, p&lt;0.05) as early as week 4; and 4) BRS with maximum effect at 12 wks (-11%, p&lt;0.05). All SHS-induced changes in cardiovascular regulation were ameliorated by 4 weeks of recovery. Treatment with TPPU in drinking water eliminated SHS exposure-induced decreases in HRV, PP and BRS. However, SHS-induced increase in activity persisted (30% higher, p&lt;0.05) even with TPPU treatment. Conclusions: These data suggest that 1) Three months of environmentally relevant SHS significantly reduces cardiac autonomic function and BP regulation; 2) cardiovascular consequences from SHS can be rescued by removing from SHS exposure; and 3) oral TPPU can prevent SHS-induced cardiovascular dysregulation. R01 ES025229, T32 HL086350, T32 ES007059, R35ES030443 This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Comparing psychological and physiological factors involved in perceived threats in behaviorally inhibited individuals

Behavioral inhibition (BI) is a temperament characteristic which is associated with increased vulnerability to stress compared to non-behaviorally inhibited (NBI) counterparts. The physiologic and psychologic substrate which underlies the difference between BI and NBI individuals is unknown. Our previously published study demonstrated that BI individuals have decreased heart rate variability (HRV) relative to NBI individuals suggesting that BI individuals have less parasympathetic nervous system (PNS) output; however, it is unknown how BI affects perceived stress. Our current study tested the hypothesis that BI individuals would have higher perceived stress and physiologic stress during transdermal electrical stimulation (TES). Participants were administered TES beginning at 5mV and increased by 5mV increments until 100mV was reached. We used the Adult Measure of Behavioral Inhibition (AMBI) and the Perceived Stress Scale (PSS) to measure perceived stress, State-Trait Anxiety Inventory (STAI) scores to measure current stress, and a series of self-reported questionnaires to measure BI. Additionally, we used a BIOPAC data acquisition system to measure heart rate (HR), HRV, and blood pressure (BP) to measure physiological stress. Our pilot data suggests there was a non-significant trend of higher perceived stress after TES in BI individuals; however, there was a significant relationship between perceived stress and STAI scores. There was no significant difference in HR, HRV and BP between BI and NBI individuals. In conclusion, our pilot data suggests that a person’s BI or NBI status affects their perceived stress after a stressor is induced. BI individuals will have higher perceived stress after a stressor is presented as opposed to NBI individuals. We will conduct further studies using TES to further study this finding. Identification of these physiological factors could provide an additional mechanism for identifying individuals who are at a higher risk for developing stress and anxiety disorders. This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Electronic cigarettes exposures modulate Heart Rate and Heart Rate Variability

Background: Despite a lack of empirical data, an unprecedented rise in electronic cigarettes (ECs) has been widely perceived as safe. Multiple studies support a causal link between tobacco cigarette (TC) use and cardiovascular (CV) diseases; however, there is a lack of data with EC use. We have previously shown that chronic and acute EC use decreases heart rate variability (HRV) in humans, likely via increased sympathetic nervous system activation. Objective: We aimed to evaluate HRV effects induced by brief EC exposures utilizing an in-vivo model for freely moving C57BL/6 mice. Methods and Results: Telemetry devices were implanted in the abdomen of six 10-week-old C57BL/6 male mice to monitor electrocardiographic activity continuously. Mice underwent an exposure protocol designed to reflect human vaping topography with two EC exposures, each lasting 15-minutes (4-sec puff/ 26-sec Air) followed by 45-min post-exposure periods. Air (primary control) and PBS (secondary control) were also included, each with their own post-exposure events. During EC exposures, we observed bradycardic effects in heart rate (HR) with the standard deviation of NN intervals (SDNN), root mean square of successive differences (RMSSD), and the proportion of adjacent normalized RR intervals that differed by more than 6 ms (pNN 6 ) significantly (p&lt; 0.05) altered as compared to Air exposures. After EC exposures, SDNN, RMSSD and pNN 6 parameters significantly decreased compared to Air. No significant differences between Air and PBS were observed in these parameters. Frequency domain parameters also indicated significant changes in HRV; the low frequency (LF) and high frequency (HF) bands showed marked increases during and after the EC exposures, while the log (LF/HF) ratio remained relatively unchanged, suggesting a possible coactivation of both parasympathetic and sympathetic branches of the autonomic nervous system. Conclusion: Short-term EC exposures lower heart rate and altered HRV in mice in an acute manner, suggesting that ECs may not be safe as previously assumed. This work was funded by the Tobacco-Related Disease Research Program (TRDRP) which included the High Impact Pilot Research Award [28IP-0036], the Cornelius Hopper Diversity Award Supplement and the Student Research Award Supplement, the UCLA Center for Occupational and Environmental Health (COEH) Student Project Award, and in part by the National Institute of Environmental Health Sciences (NIEHS) via the Student-to-Scientist Bridge program at California State University, Northridge [5R25ES025507]. This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Acute effect of interval step exercise versus continuous walk exercise on cardiovascular parameters in hypertensive postmenopausal women: A clinical, controlled, and randomized study

Aiming the prevention and treatment of hypertension, regular physical exercise has become important to reduce blood pressure. The present experiment compared the effect of interval step exercise with continuous walking exercise on cardiovascular parameters of post-menopausal hypertensive women. The volunteers were submitted to three experimental sessions: control (CO), interval exercise (IE) and continuous exercise (CE), in randomized order. The sessions lasted 120 min and during this period, resting blood pressure was evaluated after 10min of siting rest before exercise, and 30, 40 and 60min of siting rest position after exercise. Heart rate variability (HRV) were estimated at rest before exercise and 30min after exercise. Blood pressure reactivity (BPR) to the Stroop Color-Word test was measured at rest before exercise and 60min after exercise. Twelve women finished the study (59 ± 4 years and BMI of 29.78 ± 4.10 kg/m2). The One way ANOVA showed that systolic blood pressure (SBP) area under the curve over time were lower (p = 0.014) in both exercise sessions comparing with control session. The Generalized estimation equations (GEE) showed that SDNN and RMSSD indices of HRV decreases (p < 0.001) in both exercises session as well, comparing with CO. Maximal SBP during Stroop test were lower after both IE and CE exercises session comparing with CO session. We conclude that interval step exercise can reduce blood pressure responses and improve HRV acutely after its performance and these responses are similar to continuous walking exercise.

Autonomic dysfunction is associated with the development of arterial stiffness: the Whitehall II cohort.

This study aims to examine the association between baseline level and change of autonomic nervous function with subsequent development of arterial stiffness. Autonomic nervous function was assessed in 4901 participants of the Whitehall II occupational cohort by heart rate variability (HRV) indices and resting heart rate (rHR) three times between 1997 and 2009, while arterial stiffness was assessed by carotid-femoral pulse wave velocity (PWV) measured twice between 2007 and 2013. First, individual HRV/rHR levels and annual changes were estimated. Then, we modelled the development of PWV by HRV/rHR using linear mixed effect models. First, we adjusted for sex and ethnicity (model 1), and then for socioeconomic and lifestyle factors, various clinical measurements, and medications (model 2). A decrease in HRV and unchanged rHR was associated with subsequent higher levels of PWV, but the effect of a change in HRV was less pronounced at higher ages. A typical individual aged 65years with a SDNN level of 30ms and a 2% annual decrease in SDNN had 1.32 (0.95; 1.69) higher PWV compared to one with the same age and SDNN level but with a 1% annual decrease in SDNN. Further adjustment had no major effect on the results. People who experience a steeper decline in autonomic nervous function have higher levels of arterial stiffness. The association was stronger in younger people.

Sex differences in post-exercise fatigue and function in myalgic encephalomyelitis/chronic fatigue syndrome

To assess biobehavioral sex differences in myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) utilizing a low burden exercise protocol, 22 females and 15 males with ME/CFS and 14 healthy controls underwent two six-min walk tests. Fifteen daily assessments were scheduled for fatigue and function ratings and heart monitoring. Six-min walk tests were conducted on days 8 and 9. The ME/CFS group showed high self-report fatigue and impaired physical function, whereas healthy controls did not show fatigue or function abnormalities. In patients, no significant post-exercise changes were found for heart rate variability (HRV); however, heart rate decreased in ME/CFS males from Day 14 to Day 15 (p = 0.046). Female patients showed increased fatigue (p = 0.006) after the initial walk test, but a downward slope (p = 0.008) in fatigue following the second walk test. Male patients showed a decrease in self-report work limitation in the days after exercise (p = 0.046). The healthy control group evidenced a decrease in HRV after the walk tests from Day 9–14 (p = 0.038). This pilot study did not confirm hypotheses that females as compared to males would show slower exercise recovery on autonomic or self-report (e.g. fatigue) measures. A more exertion-sensitive test may be required to document prolonged post-exertional abnormalities in ME/CFS.Trial registration: NCT NCT03331419.

A longitudinal study of interoception changes in the times of COVID-19: Effects on psychophysiological health and well-being

BackgroundInteroception – the processing of the internal state of the body – has been consistently tied to well-being and mental health, which in turn have been severely challenged by the COVID-19 pandemic. Moreover, the fact that symptoms of COVID-19 (high temperature, shortness of breath, fatigue, and even gastro-intestinal problems) directly alter interoceptive signals has fueled people's tendency to constantly check their internal bodily state. ObjectivesIn this longitudinal study we tested for changes in interoception and psychophysiological health and well-being during different stages of the pandemic in 2020 and assessed their potential association. To highlight this association, we combined both subjective (i.e., self-reported questionnaires) and objective (i.e., measures of heart rate variability, HRV and of interoceptive accuracy) measures. Methods245 Italian participants who had completed the Multidimensional Assessment of Interoceptive Awareness (MAIA-2) prior to the onset of the pandemic, repeated the questionnaire during the first national lockdown in Italy, and four months after restrictions. Participants also completed survey measures of depression (PHQ-9), anxiety (STAI), and sleep disturbance (PSQI). A sub-sample of 28 participants, who had completed the heartbeat counting task (HCT) and a measure of heart rate variability (HRV), was tested again remotely, in the same time windows, using phone applications and photoplethysmography. ResultsWhile performance in the HCT remained unvaried, MAIA-2 scores consistently increased from before the pandemic to the national lockdown, and remained largely unvaried after four months. The national lockdown was associated with the lowest psychophysiological health and well-being, as evidenced by a decrease in HRV compared to before the pandemic and by higher scores in self-reported depression, anxiety, and sleep disturbance compared to four months after the lockdown. Interestingly, psychophysiological health and well-being were predicted by specific regulatory components of interoception (e.g., the ability to regulate distress by focusing on body sensations and experiencing one's body as safe and trustworthy). ConclusionsOur results suggest an increased attention towards visceral signals during the COVID-19 pandemic, and highlight the positive role of specific components of interoception in contributing to well-being, suggesting that novel interventions aimed at increasing interoception may be developed to protect against stressful life events such as COVID-19.

Heart rate variability in people with metabolic syndrome

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

Heart rate variability in people with metabolic syndrome

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

SPECTRAL ANALYSIS OF HEART RATE VARIABILITY IN PATIENTS WITH CORONARY ARTERY DISEASE

Objective: To carryout frequency domain analysis ofheart rate variability in patients with coronary arterydisease.&#x0D; Methods: Forty coronary artery disease patients with coronary artery stenosis greater than 70% of at least onevessel lumen were included. Patients with diabetes mellitus, atrial fibrillation, structural heart diseases andbundle branch block were excluded. DMS 300 4A Holter monitors were used to obtain long-term 12 leaddigital ECG recordings. Cardio Scan premium luxury software was used for analysis of heart rate variability.&#x0D; Results: The mean values of heart rate variability in patients were TP (2171.70 ± 1028.7), VLF (1661.41 ±807.88), LF (392.71 ± 227.92), HF (112.03 ± 77.90) and LF/HF ratio (4.03 ± 1.75). On comparison with normalreference values there was a significant decrease (p-value &lt; 0.05) in all parameters except VLF (p-value =0.351). TP was reduced in all the patients (100%), VLF in 26 (65%), LF in 36 (90%), HF in 36 (90%) and LF/HFratio in 29 (72.5%) patients. The difference between the frequency of patients with decreased heart ratevariability was statistically significant (p-value &lt; 0.05) except VLF (p-value = 0.082).&#x0D; Conclusion: Heart rate variability decreases significantly in patients with coronary artery disease.

Noninvasive Hypoglycemia Detection in People With Diabetes Using Smartwatch Data.

To develop a noninvasive hypoglycemia detection approach using smartwatch data. We prospectively collected data from two wrist-worn wearables (Garminvivoactive 4S, Empatica E4) and continuous glucose monitoring values in adults with diabetes on insulin treatment. Using these data, we developed a machine learning (ML) approach to detect hypoglycemia (<3.9 mmol/L) noninvasively in unseen individuals and solely based on wearable data. Twenty-two individuals were included in the final analysis (age 54.5 ± 15.2 years, HbA1c 6.9 ± 0.6%, 16 males). Hypoglycemia was detected with an area under the receiver operating characteristic curve of 0.76 ± 0.07 solely based on wearable data. Feature analysis revealed that the ML model associated increased heart rate, decreased heart rate variability, and increased tonic electrodermal activity with hypoglycemia. Our approach may allow for noninvasive hypoglycemia detection using wearables in people with diabetes and thus complement existing methods for hypoglycemia detection and warning.