Short-term Heart Rate Variability Research Articles

Elite HRV smartphone application using Polar H10 is valid for short-term heart rate variability analysis in pediatric cardiac patients.

Elite HRV smartphone application using Polar H10 is valid for short-term heart rate variability analysis in pediatric cardiac patients.

Inter- and intra-examiner reliability of short-term measurement of heart rate variability on rest in patients hospitalized with COVID-19

Measures reflecting cardiac sympathovagal activity, particularly those associated with heart rate variability (HRV), are widely recognized and utilized in both scientific and clinical contexts. This study aimed to assess the inter- and intra-examiner reliability of short-term HRV parameters in patients hospitalized with coronavirus disease 2019 (COVID-19). A total of 103 patients (both sexes) diagnosed with COVID-19 were included in the study. HRV was analyzed using both linear and nonlinear methods. Reliability was evaluated through intraclass correlation coefficient (ICC2.1), minimum detectable change (MDC), standard error of measurement (SEM), and coefficient of variation (CV). According to Fleiss’ criteria, excellent reliability was demonstrated, with ICC values ranging from 0.970 to 0.999 for Examiner 1, and from 0.956 to 0.999, for Examiner 2. In the inter-examiner analysis, the ICCs of HRV parameters ranged from 0.972 to 0.999. SEM values for intra-examiner reliability for Examiner 1 ranged from 0.02 to 5.64, with MDC values from 0.05 to 15.64, and CV (%) from 0.28 to 8.04. For Examiner 2, SEM values ranged from 0.02 to 8.18, MDC values from 0.05 to 22.68, and CV (%) from 0.24 to 8.14. For inter-examiner reliability, SEM values ranged from 0.02 to 6.17, MDC from 0.06 to 17.11, and CV (%) from 0.34 to 9.81. Across all analyses, CVs for HRV parameters remained below 10%. Considering different time points and different examiners, short-term resting HRV measurements in patients hospitalized with COVID-19, as evaluated using a portable heart rate device, exhibit high reliability.

HEART RATE VARIABILITY IN OFFSPRING OF NORMOTENSIVE AND HYPERTENSIVE PARENTS: A COMPARATIVE STUDY

Objective: This study aims to evaluate the differences in heart rate variability (HRV), a biomarker of autonomic nervous system, between offspring of normotensive and hypertensive parents to understand the genetic predisposition of autonomic dysfunction. Methods: This study was a cross-sectional observational study.Two groups of healthy adults, offspring of parents with hypertension (n = 50) and offspring of parents with normal blood pressure (n = 50). Short-term HRV was measured using 5-minute electrocardiogram (ECG). HRV indices such as time and frequency domainwere measured. Data were compared by using independent t-tests, with p < 0.05 being considered as statistically significant. Results:The offspring of parents with hypertension showed significantly lower HRV, with SDNN (30.5 ± 8.2 ms) compared to offspring of parents with normal blood pressure (45.2 ± 7.1 ms, p < 0.001). RMSSD also was significantly lower in offspring of hypertensive group. Low-frequency (LF) power was higher in offspring of parents with hypertension,while high-frequency (HF) power was significantly reduced in them compared to the normotensive group. The LF:HF ratio was higher in offspring of parents with hypertension (2.80 ± 0.85) compared to the normotensive group (1.40 ± 0.60, p < 0.001), indicating sympathovagal imbalance. Conclusion: Offspring of parents with hypertension hadlower HRV, suggesting autonomic dysfunction even in the absence of clinical hypertension. These findings emphasize the potential role of genetic predisposition in the early onset of autonomic dysregulation Further studies are required to understand mechanisms contributing to these differences in HRV.

A Cross-Sectional Study on the Effect of Stress on Short-Term Heart Rate Variability and Muscle Strength Among Construction Site Workers

This cross-sectional study investigates the immediate impact of occupational stress on short-term heart rate variability (HRV) and muscle strength among 200 construction workers in Chennai. The Perceived Stress Scale (PSS) was employed to assess stress levels, while HRV was measured using a portable ECG device, focusing on time-domain (RMSSD) and frequency-domain (HF Power) parameters. Muscle strength was evaluated using a MicroFET 2 dynamometer. Pearson correlation and multivariate regression analyses were applied to determine the associations between stress, HRV, and muscle strength, adjusting for confounding factors such as age, body mass index (BMI), and work duration. Results revealed a significant negative correlation between perceived stress and both HRV indices (RMSSD: r=-0.45, p<0.01; HF Power: r=-0.50, p<0.01) as well as muscle strength (r=-0.40, p<0.01). Higher stress levels were associated with reduced HRV and diminished muscle strength. Regression analyses confirmed that stress independently predicted lower HRV (RMSSD: ?=-0.35, p<0.01; HF Power: ?=-0.42, p<0.01) and decreased muscle strength (?=-0.32, p<0.01). These findings suggest that elevated stress negatively impacts both cardiovascular and muscular functioning, potentially increasing the health risks among construction workers. The study highlights the importance of implementing stress management interventions to improve both the physical well-being and productivity of workers in the construction industry.

Effects of six antipsychotic drug treatment regimens on short-term heart rate variability in patients with schizophrenia.

Many antipsychotic drugs have cardiac side effects due to their pharmacological actions. Heart rate variability (HRV) analysis can be used as a potential indicator of cardiotoxicity in cases where a decrease in HRV occurs after the administration of antipsychotics such as clozapine. The purpose of this study was to explore the effects of 6 antipsychotic drug regimens on short-term HRV in patients with schizophrenia. Data from 164 patients with schizophrenia between January 2018 and June 2023 were retrospectively analysed. Based on the drug used for treatment, the patients were categorised into clozapine combination (clozapine combined with aripiprazole, risperidone or ziprasidone), clozapine alone, olanzapine, aripiprazole, ziprasidone or risperidone groups. Heart rate variability indices were calculated using time domain analysis, including the standard deviation of the RR intervals (SDNN), the root mean square of successive RR interval differences (RMSSD) and the percentage of successive RR intervals over 50ms (PNN50). Compared with the pretreatment period, the SDNN, RMSSD and PNN50 were significantly lower in the clozapine combination, clozapine, olanzapine and aripiprazole groups at the end of weeks 2 and 4 of treatment (P < 0.05). However, these indicators in ziprasidone and risperidone groups did not show this significant decrease (P > 0.05). The effects of clozapine combination and clozapine on HRV were greater than for olanzapine, aripiprazole, ziprasidone or risperidone. Attention should be paid to controlling the dosage of clozapine combination and clozapine and monitoring the patient's electrocardiogram during administration.

Abstract 47: Deletion of PRR in AgRP Neurons of the Arcuate Nucleus Contributes to the Development of DOCA-Salt Hypertension

Agouti-related protein (AgRP) neurons, a key neuronal population within the arcuate nucleus (ARC), are known for their pivotal roles in regulating energy- and glucose homeostasis. However, their involvement in cardiovascular regulation remains poorly understood. Using RNAscope in situ hybridization, we found that 95.4% of the ARC AgRP neurons express the (pro)renin receptor (PRR), a component of the brain renin-angiotensin system that is crucial for blood pressure (BP) regulation. We therefore hypothesized that PRR signaling in the ARC AgRP neurons plays a regulatory role in the development of hypertension. To test this hypothesis, we selectively deleted PRR in ARC AgRP neurons by crossing AgRP-IRES-Cre mice with PRR fl/fl mice. Using RNAscope, as expected, AgRP Cre+ PRR fl/y mice displayed a significantly lower PRR mRNA in the ARC AgRP neurons than WT mice (76.3 ± 6.1 vs. 127.7 ± 2.9 AFU, p &lt; 0.05), indicating efficient ablation of PRR in ARC AgRP neurons. To examine the impact of PRR deletion in the ARC AgRP neurons on BP, the AgRP Cre+ PRR fl/y and control mice were implanted with telemetry probes to monitor BP continuously. After baseline recording, mice received DOCA-salt treatment (50 mg DOCA + saline as drinking water) for two weeks. BP variability and standard time domain heart rate variability (HRV) parameters, including overall HRV (SDNN) and short-term HRV (rMSSD), were analyzed from beat-to-beat intervals (n = 2-7 mice/group). At baseline, there was no difference between the two groups in BP, BP variability, and HRV. Two weeks of DOCA-salt induced a significantly higher BP in AgRP Cre+ PRR fl/y mice than the controls (156.2 ± 6 vs. 119.4 ± 3 mmHg, p &lt; 0.05), while BP variability did not differ between the two groups. Noteworthy, AgRP Cre+ PRR fl/y mice exhibited lower SDNN than the controls (13.3 ± 4 vs. 19.4 ± 4 ms), indicating increased sympathetic and/or reduced parasympathetic nervous activity. This lower SDNN suggests impaired cardiac autonomic function and adaptability to physiological demands in AgRP Cre+ PRR fl/y mice. Concurrently, AgRP Cre+ PRR fl/y mice showed a lower rMSSD (4.7 ± 0.5 vs. 10.8 ± 3.5 ms), implying reduced parasympathetic activity. In conclusion, deletion of PRR in the ARC AgRP neurons results in compromised cardiac autonomic function associated with the development of hypertension. Our findings underscore a novel protective role of PRR signaling in the ARC AgRP neurons in BP regulation.

Intra- and Inter-Rater Reliability of Linear and Nonlinear Measures of Short-Term Heart Rate Variability Following Combat-Related Traumatic Injury.

Heart rate variability (HRV) is a marker of autonomic function. However, the reliability of short-term HRV measurement in individuals with combat-related traumatic injury (CRTI) remains undetermined. An intra- and inter-rater reliability study was conducted using a subsample (n = 35) of British servicemen with CRTI enrolled in the ongoing ADVANCE study. A five-minute epoch of single-lead electrocardiogram data collected during spontaneous breathing was used to measure HRV. HRV analyses were independently performed by two examiners using Kubios. Intraclass correlation coefficient (ICC), standard error of measurement (SEM), minimum detectable change (MDC), and coefficient of variance were calculated for linear [root mean square of successive difference (RMSSD), standard deviation of NN interval, low-frequency, high-frequency, total power] and nonlinear (SD1-2, acceleration and deceleration capacities, sample entropy) measures. Bland-Altman %plots were used to assess bias in intra- and inter-rater HRV data. The mean age of participants was 39.3 ± 6.3 years. An excellent ICC score of 0.9998 (95% CI 0.9997, 0.9999) was observed for intra-rater analyses of RMSSD, and similar excellent ICC scores were seen for all other HRV measures. The inter-rater reliability analyses produced an excellent ICC score (range 0.97-1.00). Comparatively, frequency-domain measures produced higher MDC% and SEM% scores than time-domain and nonlinear measures in both inter- and intra-rater analyses. The Bland-Altman plots revealed relatively higher bias for frequency-domain and nonlinear measures than time-domain measures. ECG-related short-term HRV measures were reliable in injured servicemen under spontaneous breathing. However, the reliability appeared better with the time-domain measure than frequency-domain and nonlinear measures in this sample.

Autonomic Changes Associated with Clinical Depression as Assessed by Short-term Heart Rate Variability (HRV): A Comparative Study

Autonomic Changes Associated with Clinical Depression as Assessed by Short-term Heart Rate Variability (HRV): A Comparative Study

Day-to-day reliability of basal heart rate and short-term and ultra short-term heart rate variability assessment by the Equivital eq02+ LifeMonitor in US Army soldiers

IntroductionThe present study determined the (1) day-to-day reliability of basal heart rate (HR) and HR variability (HRV) measured by the Equivital eq02+ LifeMonitor and (2) agreement of ultra short-term HRV...

Agreement between Ultra-Short-Term and Standard Heart Rate Variability Analysis in Resting and Post-Exercise Conditions.

Short-term (5 min) heart rate variability (HRV) analysis is widely used in assessing autonomic nervous system activity during exercise. While shortening the HRV measurement duration can help improve its application efficiency, its accuracy needs to be verified. This study investigated the agreement between ultra-short-term (UST) HRV (3 or 4 min) and standard 5 min HRV and explored the optimal recording duration under resting and post-exercise conditions. Fourteen participants exercised on a cycle ergometer at 60% of their maximum peak power. Data were collected during the rest condition (Pre-E) and three post-exercise conditions (Post-E1, Post-E2, and Post-E3), with indicators of the standard deviation (SDNN) of the ultra-short and short-term RR intervals and the root mean square (RMSSD) of the continuous difference between RR intervals. Repeated measures ANOVA, Cohen's d statistic, Bland-Altman analysis, and interclass correlation coefficients (ICC) assessed the agreement between UST-HRV and ST-HRV. The consistency results of SDNN and RMSSD in resting and post-exercise were different. At the Pre-E, Post-E2, and Post-E3 phases, no statistical differences for SDNN and RMSSD were observed, with ICCs surpassing 0.9, indicating a high level of agreement. However, at Post-E2, there was a significant difference between 3 min RMSSD and 5 min RMSSD (p < 0.05), as well as between 3 min SDNN, 4 min SDNN, and 5 min SDNN (p < 0.05). Furthermore, the limits of agreement were observed to decrease as the time duration increased in Bland-Altman plots. UST-HRV analysis is a reliable substitute for standard 5 min HRV assessment, particularly during resting conditions. For post-exercise measurements, assessing the appropriateness of a 3- or 4 min duration based on the exercise's length is recommended to ensure accuracy and reliability.

Cardiohemodynamic responses and heart rate variability following an active orthostatic test among male residents of the North with different NOS3 (rs2070744) genotypes

AIM: This study explored associations between the -786TC (rs2070744) genetic polymorphism of the NOS3 gene and the main indices of systemic hemodynamics and heart rate variability following an active orthostatic test in men living in the North. MATERIAL AND METHODS: Eighty-three healthy men aged 33.5±1.5 yеаrs on average, who were permanent residents of the Magadan Region, comprised the sample. The participants underwent both resting and active orthostatic testing modes. Cardiovascular system variables were recorded using an automatic tonometer. Hemodynamic indices were then calculated. Short-term heart rate variability in frequency and spectral areas was simultaneously measured using the Varikard hardsoft complex unit. Genotyping was conducted using polymerase chain reaction. The sample was then divided into two groups: Group 1 consisted of homozygotes with the TT genotype (n=34), while Group 2 comprised carriers of the NOS3*C allele variant (genotypes TC+CC) associated with reduced nitric oxide production (n=49). RESULTS: By examining the complex vasomotor, chrono- and inotropic reactions of hemodynamic and heart rate variables during the active orthostatic test, we were able to discern unique patterns in the response of the two groups under study. Men in Group 1 demonstrated an elevated cardiac output response during orthostatic changes, while maintaining consistent vascular resistance values. This was accompanied by a shift towards sympathetic autonomic activity and an increase in the very low-frequency component of heart rate variability. In Group 2, individuals with sympathetic insufficiency and increased vascular resistance during the orthostatic test showed a 35% increase in the low-frequency component of the cardiac rhythm reflecting the importance of this indicator as a stimulator of blood pressure rhythm fluctuations mediated by baroreflex mechanisms. CONCLUSION: Our findings suggest that men lacking the NOS3*С allele variant in their genotype demonstrate more favorable responses to the active orthostatic test. This may reflect higher level of cardiovascular functional reserves. The 786TC (rs2070744) polymorphism of the NOS3 gene can be considered as a marker of cardiohemodynamic status and autonomic regulations during functional exercise, such as an active orthostatic test.

Feasibility and determinants of short-term heart rate variability in patients using photoplethysmography-based wearable devices - data derived from TeleCheck-AF

Abstract Background Heart rate variability (HRV), especially short-term HRV, is known to be associated with development of atrial fibrillation (AF). Nevertheless, it is not known if short-term HRV can be feasibly derived from digital devices in patients at risk for AF. In this analysis, we aimed to evaluate the feasibility and determinants of short-term HRV using non-continuous photoplethysmography (PPG) recordings derived from digital hand-held device. Methods TeleCheck-AF is a project implementing an on-demand app-based infrastructure for the management of AF. Briefly, one week prior to the scheduled teleconsultation, patients were provided with a smartphone app to assess heart rate/rhythm three times a day and in case of symptoms. Patients from the project with at least one PPG recording in sinus rhythm (SR) during the study period were analyzed. For every recording in SR, the short-term HRV parameter, root mean square of successive normal-to-normal interval differences (RMSSD), was calculated. The PPG parameters, heart rate and RMSSD, were compared between groups (men vs women, presence vs absence of previous AF, atrial flutter, atrial tachycardia, pulmonary vein isolation (PVI) within 12 months). Results Overall, 855 patients [60.5% men, median age 63 (56;70) years] with a total number of 13465 recordings were included in the analysis. Median number of recordings per patient was 15 (7;20) with a median heart rate of 66 (59;75)bpm and a RMSSD of 39.7 (30.6 ;56.1)ms. Results revealed a significant difference in RMSSD for gender and previously known AF, whereas no difference was seen e.g., for patients with known atrial flutter or atrial tachycardia (table 1). In patients with previously known AF, patients who underwent PVI within the last 12 months had a reduced RMSSD in comparison to patients without previous PVI (36.7 (31.8; 47.0)ms vs 42.2 (34.4; 54.3)ms, p&amp;lt;0.001). Conclusion Assessing short-term HRV based on RMSSD using PPG recordings is feasible. Short-term HRV recorded by digital hand-held devices may be especially helpful in patients after PVI as such patients were shown to have a reduced HRV in this analysis. Table 1: Differences in short-term heart rate variability in patients at risk for atrial fibrillation. AF = Atrial fibrillation.Table 1

Photoplethysmography recordings preceding onset atrial fibrillation show a higher heart rate variability - a TeleCheck-AF subanalysis

Abstract Background An increased heart rate variability (HRV), mostly assessed by 12-lead electrocardiogram (ECG) or long-term Holter monitoring, can be associated with the onset of atrial fibrillation (AF). Data evaluating HRV measurements using digital devices, especially those using photoplethysmography (PPG), in patients at risk for AF are sparse. In this analysis, we aimed to assess if hand-held-based non-continuous PPG measurements can provide short-term HRV to predict AF. Methods Patients from the TeleCheck-AF project with at least one PPG measurement in AF and one measurement in sinus rhythm (SR) were analyzed. Briefly, patients were provided with a PPG-based heart rate/rhythm monitoring smartphone app. They were instructed to record a PPG measurements three times daily and in case of symptoms for seven consecutive days. Short-term HRV using root mean square of successive normal-to-normal interval differences (RMSSD) was calculated in recordings in SR and compared between those not preceding and preceding an episode of AF (figure 1). Results Overall, 136 patients [56.3% men, median age 66 (59; 72) years] were included in the analysis. Median total number of recordings per patient was 24 (19; 30) including 4 (2;7) AF episodes per 1 week recording period. RMSSD was significantly higher in PPG measurements preceding an AF episode than in PPG measurements not preceding an AF episode [42.5 (33.2;70.7)ms vs. 41.1 (32.4;54.7)ms; p&amp;lt;0.001]. Between-group comparison revealed no significant difference for gender, age, previous ablation or betablocker therapy (p=0.824; p=0.484; p=0.519 and p=0.624, respectively). Conclusion Short-term HRV based on RMSSD, assessed by digital hand-held devices is significantly higher in PPG recordings preceding an AF episode than in measurements not preceding a consecutive AF episode. Whether PPG-recording derived short-term HRV can help to predict onset-AF warrants further study in larger populations. Figure 1: Patient example and exemplary analysis scheme, depicting the total number of recordings (n=14). HRV of recordings in sinus rhythm (SR) not preceding an episode of atrial fibrillation (AF) (A; grey circles) were compared to recordings preceding a consecutive AF episode (B; blue circles).Figure 1

Assessing heart rate fragmentation to predict atrial fibrillation in the general population aged 65

Abstract Rationale Screening the general population aged 65 for atrial fibrillation (AF) has been proposed as a preventive measure against potential complications. The dysfunction of the autonomic nervous system (ANS) plays an important role in atrial fibrillation (AF). Short-term HRV is conceptually attributed to physiologic vagal tone modulation. But recent data suggest that a component of short-term HRV, called heart rate fragmentation (HRF), is related to ANS breakdown and may be a predictor of AF occurrence. Metrics derived from heart rate variability (HRV) that depict heart rate fragmentation (HRF) have been suggested to reflect autonomic nervous system (ANS) dysfunction. Objectives To assess the predictive capacity of HRF markers for AF occurrence over an 18-year follow-up in individuals aged 65 at the study’s inspection and to develop a predictive score for AF onset. Methods A cohort study was designed to prospectively assess the predictive value of ANS activity level among general population regarding cardiovascular events and mortality. 1011 subjects aged 65 were enrolled in the study from September 2000 to December 2002. The study population had no history of AF and a low cardiovascular risk. A median follow-up of 17.8 years was managed. HRV data were acquired by 24-h Holter electrcardiogram (ECG) monitoring at baseline and assessed by frequency domain and time domain methods. Heart rate fragmentation using the percentage of inflection points (PIP) and alpha 1-index (using fractal evaluation of NN intervals) were then calculated. The study outcome was the development of AF during follow-up, defined as a standard 12-lead ECG recording or Holter recording with ≥ 30 s of AF. Results AF was diagnosed in 123 patients during the 18-year follow-up, representing a cumulative incidence of 13.4%. Using multivariate analysis, the occurrence of AF was independently predicted by the male gender (HR=1.74, 95%CI:1.16-2.63, p&amp;lt;0.01), a heart rate below 70bpm (HR=1.85, 95%CI:1.18-2.90, p&amp;lt;0.01), an increased percentage of NN intervals that differ by more than 50 ms from the previous interval (pnn50) (HR=1.69, 95%CI:1.06-2.70, p=0.03), an increased percentage of inflection points (HR=2.80, 95%CI:1.66-4.72,p&amp;lt;0.01), and a reduced alpha 1 index (HR=1.61, 95%CI:1.03-2.53, p=0.04). Given these results, a predictive score was built up based on the 4 independent predictors, ranging from 0 to 6 (Graphical Abstract). The high-risk group, defined as having a PROOF-AF score of 4 or higher, exhibited a 3.3-fold higher risk of developing AF (Figure). The PROOF-AF score demonstrated superior predictive performance compared to other available risk scores for incident AF such as CHARGE-AF score, C2HEST score, FHS score, and JMC score. Conclusion HRF parameters, included in the PROOF-AF score, may be used to identify individuals aged 65 without pre-existing health conditions who are at high-risk of developing AF and assist population screening.Graphical abstractFigure

Association of sex with heart rate variability in atrial fibrillation patients

Abstract Background Sex-specific differences in cardiac autonomic tone have not been thoroughly investigated in patients with atrial fibrillation (AF) but may play a relevant role. Purpose We aimed to investigate cardiac autonomic function of female compared to male AF patients by means of short-term heart rate variability (HRV) analysis. Methods In this cross-sectional analysis, we enrolled 1150 patients from the Swiss-AF cohort study with 5-minute resting ECG recordings in sinus rhythm. We calculated the following HRV parameters: HRV triangular index (HRVI), standard deviation of NN intervals (SDNN), root mean square of successive differences, mean heart rate, power in the high frequency and low frequency range. We fitted linear regression models to analyze the association between gender and HRV variables adjusted for age, intake of betablockers, hypertension, diabetes and heart failure. Results 361 patients (29%) were female (mean age 72.9±7.8 years), 789 (68.6%) were male (mean age 69.8±8.5 years). In the multivariable adjusted models, female sex was associated with significantly lower values of HRVI (β = -0.74; 95% CI -1.44- -0 04, p=0.039) and SDNN (β = 8.95; 95% CI 0.162-17.7, p=0.046). This association persisted in all three age tertiles (&amp;lt;68 years, 68-75 years and ≥ 75 years of age). Conclusions In an elderly AF cohort, female sex is associated with reduced global autonomic activity. Whether this is associated with an adverse prognosis has to be investigated.

Effects of stress management interventions on heart rate variability in adults with cardiovascular disease: a systematic review and meta-analysis.

Meta-analysis was used to investigate the potential benefits of stress management interventions (SMIs) on vagally-mediated heart rate variability (HRV) in adults with cardiovascular disease. Electronic bibliographic databases were searched through August 2022. Randomized controlled trials and quasi-experimental studies assessing effects of SMIs on HRV were included. Methodological quality was assessed with a standardized checklist. A pooled effect size was calculated for vagally-mediated HRV indices (standard deviation of normal-to-normal intervals, root mean square of the successive differences, and high frequency power) using random effects models. Fourteen studies (1202 participants, Mage: 59 ± 6.25years; 25% ± 16% women; 61% ± 22% White) were included. Ten studies (11 effects) reported short-term HRV assessment; a small between-group difference emerged for vagally-mediated HRV (d+ = .27, 95% confidence interval [CI] 0.01-0.52, k = 11). Most interventions examined biofeedback; these studies yielded a small between-group difference on vagally-mediated HRV (d+ = 0.31, 95% CI 0.09-0.53, k = 7, Q [6] = 3.82, p = .70, I2 = 11%). This is the first systematic examination of the effect of SMIs on HRV in adults with CVD. Findings suggest a small effect of SMIs on vagally-mediated HRV, with biofeedback likely driving the effect. More research is required to fully understand whether this benefit on vagally-mediated HRV applies to other SMIs.

The effect of breathing hypoxic gas (15% FIO2 ) on physiological and behavioral outcomes during simulated driving in healthy subjects.

Hypoxia is mainly caused by cardiopulmonary disease or high-altitude exposure. We used a driving simulator to investigate whether breathing hypoxic gas influences driving behaviors in healthy subjects. Fifty-two healthy subjects were recruited in this study, approved by the Science and Engineering Ethical Committee. During simulated driving experiments, driving behaviors, breathing frequency, oxygen saturation (SpO2 ), and heart rate variability (HRV) were analyzed. Each subject had four driving sessions; a 10-min practice and three 20-min randomized interventions: normoxic room air (21% FIO2 ) and medical air (21% FIO2 ) and hypoxic air (equal to 15% FIO2 ), analyzed by repeated measures ANOVA. Driving behaviors and HRV frequency domains showed no significant change. Heart rate (HR; p < 0.0001), standard deviation of the RR interval (SDRR; p = 0.03), short-term HRV (SD1; p < 0.0001), breathing rate (p = 0.01), and SpO2 (p < 0.0001) were all significantly different over the three gas interventions. Pairwise comparisons showed HR increased during hypoxic gas exposure compared to both normoxic interventions, while SDRR, SD1, breathing rate, and SpO2 were lower. Breathing hypoxic gas (15% FiO2 , equivalent to 2710 m altitude) may not have a significant impact on driving behavior in healthy subjects. Furthermore, HRV was negatively affected by hypoxic gas exposure while driving suggesting further research to investigate the impact of breathing hypoxic gas on driving performance for patients with autonomic dysfunction.

Effect of psychosocial factors on autonomic nervous system activity in patients with heart failure.

Autonomic imbalance predicts worse clinical outcomes in patients with heart failure (HF). Managing the variables affecting heart rate variability (HRV) might improve the clinical outcomes of patients with HF. This study aimed to investigate variables affecting HRV. We assessed autonomic nervous system activity (low-frequency [Lf], high-frequency [Hf], and Lf/Hf ratio) in 60 patients with HF, employing standard measures to capture short-term HRV. To estimate the independent effects of variables such as well-known cardiac risk factors and psychosocial conditions on HRV, multivariate analyses were conducted. For psychosocial variables, we assessed depression and quality of life in patients and their family caregivers. We also assessed the self-care behavior of patients and their caregivers' burden. Depression in family caregivers and self-care behavior of patients were independently associated with a decreased Hf (β-coefficient = 0.309, P = .039 and β-coefficient = -0.029, P = .047, respectively). Depression of family caregivers and self-care behavior of patients may affect HRV in patients with HF.

Cardiac Autonomic and Endothelial Function in Acute Lymphoblastic Leukaemia Patients Immediately After Chemotherapy and at the Three-Month Follow-up.

Acute lymphoblastic leukemia (ALL) is a malignant uncontrolled overproduction of immature lymphoid cells in blood and bone marrow. The primary treatment of ALL is chemotherapy. Chemotherapy can have myriad systemic side effects, notably cardiovascular derangement. Autonomic derangement occurrence in cancer patients signifies cardiovascular risk in them and is a determinant of cardiovascular morbidity and mortality. Elevated soluble vascular cell adhesion molecule-1 (sVCAM-1) and soluble intercellular adhesion molecule-1 (sICAM-1) levels implicated in the regulation of inflammation indicate endothelial dysfunction. High levels of high-sensitivity C-reactive protein (hsCRP) can be indicative of low-grade inflammation. Hence, in this study the cardiac autonomic function and endothelial and inflammatory biomarker levels in adult patients with ALLwere assessed immediately and three months after chemotherapy. In this longitudinal study, 30 ALL patients (23 males, seven females) aged between 18 to 50 years, who had completed chemotherapy regimens, and 30 age and gender-matched healthy participants (controls) were recruited. Cardiac autonomic function tests (short-term heart rate variability (HRV), 30:15 ratio, synaptic excitation and inhibition (E/I) ratio, diastolic blood pressure (DBP) response to isometric hand grip), endothelial markers (sVCAM-1 and sICAM-1), and inflammatory marker (hsCRP) were assessed immediately and at three months after chemotherapy. Magnitudes of time domain and frequency domain indices, conventional autonomic function test indices, and biomarkers were deranged in ALL patients immediately after chemotherapy. After three months, cardiac autonomic function parameters were found to improve in the form of increased root mean square of successive differences between normal heartbeats (RMSSD), standard deviation of the interbeat intervals of normal sinus beats (SDNN), total power, high-frequency (HF)nu, and decreased low-frequency(LF)nu & LF-HF ratio. Endothelial (sVCAM-1) and inflammatory markers (hsCRP) were lower in the patient group as compared to the controls immediately after chemotherapy. Three months after chemotherapy, the levels of endothelial and inflammatory markers did not show much change. In this study, we found ALL patients showed higher sympathetic drive, decreased parasympathetic modulation, and sympathovagal imbalance immediately after chemotherapy as compared to the controls, indicating cardiovascular risk. After three months, improvement in cardiovascular autonomic function was observed. ALL itself is a state of inflammation with elevated endothelial and inflammatory markers; thus, the decreased endothelial and inflammatory markers could be attributed to the immediate effect of chemotherapy.

Does Osteopathic Heart-Focused Palpation Modify Heart Rate Variability in Stressed Participants with Musculoskeletal Pain? A Randomised Controlled Pilot Study.

Heart rate variability (HRV) describes fluctuations in time intervals between heartbeats and reflects autonomic activity. HRV is reduced in stressed patients with musculoskeletal pain and improved after osteopathic manipulative treatment and mind-body interventions. Heart-focused palpation (HFP) combines manual and mind-body approaches to facilitate relaxation. This randomised controlled pilot study investigated the feasibility and sample size for a future randomised controlled trial and the effect of a single treatment with HFP or sham HFP (SHAM) on short-term HRV. A total of Thirty-three adults (47.7 ± 13.5 years old) with stress and musculoskeletal pain completed the trial with acceptable rates of recruitment (8.25 subjects per site/month), retention (100%), adherence (100%), and adverse events (0%). HFP (n = 18), but not SHAM (n = 15), significantly increased the root mean square of successive RR interval differences (p = 0.036), standard deviation of the NN intervals (p = 0.009), and ratio of the low-frequency to high-frequency power band (p = 0.026). HFP and SHAM significantly decreased the heart rate (p < 0.001, p = 0.009) but not the stress index and ratio of the Poincaré plot standard deviation along and perpendicular to the line of identity (p > 0.05). A power analysis calculated 72 participants. Taken together, the study was feasible and HFP improved HRV in stressed subjects with musculoskeletal pain, suggesting a parasympathetic effect.