HF Norm Research Articles

Slow breathing exercise improves cardiac autonomic tone in hypothyroid patients: a frequency domain analysis of HRV

Background: Hypothyroidism is associated with autonomic dysfunction and oxidative stress. Slow breathing exercise (SBE), a yoga-based relaxation technique, improves cardiac autonomic nerve function by changing sympathetic or parasympathetic activity. Objective: To assess the effect of SBEon cardiac autonomic tone and in hypothyroid patients. Methods: This non randomized controlled trial was conducted on 50 newly diagnosed drug naive female hypothyroid patients (18-45 years of age)recruited from the outpatient department of the Department of Endocrinology, Bangabandhu Sheikh Mujib Medical University,(BSMMU), Shahbag, Dhaka. Twenty five apparently healthy female subjects formed control group. . Among the 50 hypothyroid patients, 25 were consecutively assigned with SBE for 90 days (Group SBE) and the remaining 25 patients were without SBE and followed up after 90 days (Group NSBE). Both groups of patients received treatment with thyroid hormone replacement during their follow up period. Control group did not perform SBE or any other exercise. Data were recorded at baseline(Day 0) and after 90 days in all the subjects. Based on data recording period SBE group was designated as SBE0(at day 0 or pre intervention)and SBE90(at day 90 or post intervention). Similarly, NSBE0(day 0) and NSBE90 (day 90) and control group was also designated as control0 (day 0) and control90 (day 90).Resting cardic autonomic tonic activity was assessed by frequency domain analysis of Heart Rate Variability(HRV). HRV data were recorded by a digital data acquisition device Power Lab, AD Instrument Australia. Data were expressed as mean±SD. For statistical analysis, ANOVA followed by post hoc Bonferroni test and paired sample “t” test were done. Results: At baseline i.e. at day 0 before follow up, diastolic blood pressure (DBP) (p<0.05), low frequency in normalized unit (LF norm) (p<0.001), low frequency/high frequency ratio (LF/HF) (p<0.001) were significantly higher and total power (TP) (p<0.001), low frequency power (LF power) (p<0.01), high frequency power (HF power) (p<0.001), high frequency power in normalized unit (HF norm) (p<0.001) were significantly lower in hypothyroid patients (group SBE0and NSBE0 ) compared to healthy control (group control0). After 90 days of intervention with SBE, SBP, DBP, LF norm, LF/HF ratio decreased significantly and TP, HF power, HF norm increased significantly in group SBE90 compared to SBE0. Whereas, in group NSBE90, after 90 days of follow up, LF norm, LF/HF ratio decreased significantly and HF power, HF norm increased significantly compared to NSBE0. Again, after 90 days of follow up/SBEHF norm were significantly higher and LF norm, LF/HF ratio were significantly lower in SBE90 compared to NSBE90. In addition, significant difference was present in all these parameters between NSBE90 and control90. Also, after 90 days of SBELF norm, HF norm and LF/HF ratio was not significantly different from control. Conclusions: Based on these results, it can be concluded that autonomic dysfunction characterized by reduced vagal tone and sympathetic hyperactivity occurred in drug naïve hypothyroid patients. In addition, thyroid hormone replacement therapy improved autonomic dysfunction by increasing parasympathetic and decreasing sympathetic tonic activity. Moreover, SBE caused further improvement of autonomic dysfunction and could restore sympathovagal balance to its normal state in these patients. J Bangladesh Soc Physiol 2023;18(1): 9-18

Frequency Domain Parameters of Heart Rate Variability in Patients with Gastro-Oesophageal Reflux Disease

Background: Gastro-oesophageal reflux disease (GERD) has been associated with autonomicnervous dysfunction along with reduced Heart Rate Variability.Objective: To observe cardiac autonomic nerve function status by heart rate variability analysis inpatients with Gastro-oesophageal reflux disease (GERD).Methods: This cross-sectional study was carried out in the Department of Physiology, SirSalimullah Medical College (SSMC), Dhaka from 1st January, 2017 to 31st December, 2017.Forthis, total 30 male and female diagnosed GERD patients from the Out Patient Department(OPD) of Gastroenterology, BSMMU aged 20-35 years were included in the study group. LowFrequency norm (LF norm),High Frequency norm (HF norm) and LF/HF ratio of HRV parameterswere recorded. Thirty age and BMI matched healthy subject also included as control. For statisticalanalysis, unpaired t-test was done as applicable.Results: The mean LF norm was 72.10±13.97 n.u. and the mean LF/HF was 3.34±1.14. Whichwere significantly (p<0.001) higher in GERD patients in comparison to that of healthy subjects.Which indicate sympathetic overactivity in GERD patients. However, the mean HF norm was24.54±10.56 n.u. Which was significantly (p<0.001) lower in GERD patients as compared to that of apparently healthy subjects. Which indicate decreased parasympathetic activity in GERDpatients.Conclusion: Parasympathetic hypofunction and sympathetic over activity were found in GERDpatients.

Вплив об’ємного пневмопресингу низької інтенсивності в осіб з різним типом регуляції автономної нервової системи на центральну гемодинаміку

The purpose of our study was to determine changes in central hemodynamics under the condition of exposure to low-intensity IPC on the lower limbs in individuals with different types of regulation of the autonomic nervous system. The group of 62 participants in age of 18-22 years were investigated. Testing session that included pressure of 40 mmHg and 20-minute period of temporary occlusion of the lower extremities was performed by intermittent pneumatic compression with Recovery Pump PRX device (“Mego Aftek AC Ltd”, Israel). Before, during the exposure and recovery period of the procedure arterial blood pressure was recorded with Korotkov’s auscultative method by mercury tonometer (“Dr.Frei”A-10, Switzerland). For monitoring hemodynamic changes impedance cardiography (ICG) method was applied (“ХАІ-medica”, Kharkiv, Ukraine), by 15 sec. Based on the spectrum power values in the range of 0.15-0.4 (HFnorm), which was calculated according to the formula HFnorm = HF/(HF+LF)∙100%, 3 groups of volunteers were determined by method of sigma deviations. The 1st group included 29 people with a predominance of the sympathetic link of regulation of the autonomic nervous system, HF norm at rest is less than 40 nu. The 2nd - 19 people with a normotonic type of regulation, HFnorm from 40 to 60 nu. The 3rd - 14 people with a predominance of the parasympathetic link, HF norms higher than 60 nu. It has been established that in persons of the 1st group blood pressure maintenance is a result of complex neurohumoral interactions, in the 3rd group - due to vascular components. The decrease in the heart rate and cardiac index in the 1st and 2nd groups is caused by a decrease in venous return to the heart, and in the 3rd group - by contractile function of the heart. The proven impact of non-invasive IPC on peripheral blood circulation improving supports the concept of orthostatic tolerance. Future long-term studies are needed to evaluate the further long-term efficacy of IPC, safety and tolerability of this approach in clinical practice.

COMPREHENSIVE ASSESSMENT OF PSYCHOPHYSIOLOGICAL FACTORS IN THE PROFESSIONAL ADAPTATION OF CADET-GRADUATES TO MILITARY SERVICE

The article provides a comprehensive assessment of the psychophysiological factors affecting the professional adaptation of cadets. It emphasizes that professional development entails the formation of professional orientation, competence, socially significant and professionally important qualities, their integration, readiness for continuous professional growth, and the search for optimal methods to perform activities of high quality and creativity in accordance with individual psychological characteristics. Various approaches to specialist development have been examined by researchers and practitioners, including professional self-determination, stages of specialization, development of professionally important qualities, motivation in work activities, and the fundamentals of labor activity. The main theories that unify these approaches are the theory of types of professional life (structural concepts), motivational theories, and theories of individuality. The study highlights that the adaptation process is influenced by personal factors such as stress resistance, personality type, and emotional perception. The research utilized data obtained through a rhythmograph system, which monitors ECG signals and heart rate variability in the first standard lead, allowing for statistical time and spectral analysis of heart rate. In the initial stage, the assessment of nonverbal and general intelligence development levels was analyzed using the "Color Progressive Matrices" test by J. C. Raven. In the subsequent stage, the correlation between intelligence level and LF norm, HF norm, and LnLF/HF under load was determined. Finally, the adaptability level of the respondents to modern functioning conditions was assessed using the multi-level personality questionnaire "Adaptability" by A. Maklakov and S. Chermianin. The obtained data indicate an inverse proportional relationship between these indicators: "high stress - low adaptability" and vice versa. The article also highlights the significance of nervous-psychic tension, in addition to stress, as an unfavorable factor affecting performance. It lists the main causes contributing to the development of nervous-psychic tension. Furthermore, the works of M. Agadzhanyan, V. Kaznacheev, and S. Kaznacheev identify three qualitatively different types of adaptive human response: "sprinter," "stayer," and "intermediate" types (based on the criterion of time to perform submaximal work). To enhance adaptive abilities, the article proposes the utilization of the bioactivation optimization technique, which effectively enhances a person's psychophysiological functions and meets the requirements for psychophysiological support in military professional activities.

Relationship Between Anxiety and Heart Rate Variability in Elderly Insomnia Patients

Objective: This study investigated the association between anxiety symptoms in elderly insomnia patients and heart rate variability (HRV) parameters. Methods: In total, 46 elderly patients (67.91±5.61 years old, 11 males, 35 females) were enrolled. The Pittsburgh Sleep Quality Index, Beck Anxiety Inventory, Albany Panic and Phobia Questionnaire (APPQ), Penn State Worry Questionnaire, and Liebowitz Social Anxiety Scale were used to measure sleep quality and anxiety. Resting-state HRV was also obtained. The associations between anxiety measures and HRV were analyzed. Results: Female sex was related to higher normalized high-frequency (HF norm) power (β=0.32, p=0.04). The APPQ score was negatively correlated with the HF norm (β=-0.59, p<0.01). Age was negatively correlated with low-frequency power/high-frequency power (LF/HF) ratio (β=-0.33, p=0.04). Female sex was correlated to lower LF/HF ratio (β=-0.36, p=0.02). The APPQ score was positively correlated with LF/HF ratio (β=0.68, p<0.01). Conclusion: Panic symptoms in elderly insomnia patients were negatively correlated with parasympathetic nervous system activity.

Repeated Exposure to Mild Intermittent Hypoxia Mitigates the Severity of OSA, Reduces Blood Pressure and Improves Microvascular Function and Walking Endurance in Adults with OSA for 4 ‐ 8 Weeks Post Therapy

ObjectiveWe previously reported that repeated exposure to mild intermittent hypoxia (MIH) improves autonomic function and lowers blood pressure (BP) in adults with hypertension and obstructive sleep apnea (OSA). We also showed that the reduction in BP was concurrent with an improvement in upper airway (UA) collapsibility that might lead to a reduction in the severity of OSA. However, whether mitigation of OSA severity occurs and whether decreases in BP and UA collapsibility are sustained for long periods of time is unknown. Moreover, whether improved microvascular (MV) function is coupled to reductions in BP following MIH is unknown in OSA. Improved MV function could lead to increased oxygen availability to skeletal muscles and improved exercise endurance. Thus, we investigated if MIH promotes long‐term positive effects on UA collapsibility, BP, MV function and walking endurance in adults with hypertension and OSA.MethodsTwo males (age: 46 ± 7 yrs; BMI: 32.5 ± 2.3 kg/m2; systolic BP: 158 ± 6 mmHg) with OSA [apnea hypopnea index (AHI): 55.7 ± 2.8 events/hr] were exposed to twelve 2‐min hypoxic episodes (PETO2 ≍ 50 mmHg) separated by 2‐min normoxic intervals with sustained PETCO2 maintained 2 mmHg above baseline for 15 days and were treated with in‐home continuous positive airway pressure on nightly basis throughout the study. The active critical closing pressure (Acrit), AHI, 24‐hr BP, BP variability, post‐occlusion reactive hyperemia (PORH), and fatigability (i.e. 10‐min walk test) were measured before and 1 day, 4 weeks and 8 weeks after exposure to MIH. Based on the small sample size, Cohen’s D effect sizes are reported. Data are expressed as Δ from baseline ± SE.ResultsSystolic BP was reduced 1 day after (17.2 ± 2.1 mmHg, d = 2.4), and 4 (12.8 ± 1.2 mmHg, d = 1.7) and 8 wks. (4.1 ± 0.7 mmHg, d = 0.5) after MIH. Likewise, improvements in autonomic function were evident at the three time points after MIH (HF norm: 23 ± 19, 8 ± 7 and 11 ± 5 n.u. LF norm: ‐26 ± 14, ‐10 ± 3 and ‐13 ± 3 n.u., d > 0.8 for all measures). Acrit decreased (‐2 ± 0 cmH2O) following MIH and the magnitude of this response was sustained for 4 and 8 wks. after MIH (d = 0.7 for all measures). Similarly, the AHI decreased at the three time points (‐10 ± 1.5 events/hr, d = 3.1, ‐20 ± 3 events/hr, d = 7.2, ‐24 ± 0.9 events/hr, d = 5.2) after MIH. In addition, the PORH response increased immediately after the MIH protocol (12.6 ± 2.2%, d = 5.9) and remained elevated at 4 wks. post MIH (3 ± 0.7%, d = 3.6) before returning to baseline values 8 wks. after MIH. The 10‐min walking distance increased (217 ± 48 m, d = 3.9) and fatigability reduced (‐17 ± 3.4% reduction in d = 4.9) 1 day following the MIH protocol. These modifications were sustained for 4 wks. (+151 ± 9 m, ‐11 ± 0.3% respectively, both d > 0.8) and 8 wks. (+86 ± 38 m, ‐6 ± 2% respectively, both d > 0.8) after MIH.ConclusionOur preliminary results suggest that exposure to MIH improves UA collapsibility and reduces the severity of OSA. Likewise, BP is reduced, and MV function is improved leading to increased walking endurance in adults with OSA. These modifications may be sustained for up to 8 weeks.

Study on the nonfatigue and fatigue states of orchard workers based on electrocardiogram signal analysis

In recent years, fatigue has become an important issue in modern life that cannot be ignored, especially in some special occupations. Agricultural workers are high-risk occupations that, under fatigue conditions over a long period, will cause health problems. In China, since very few studies have focused on the fatigue state of agricultural workers, we were interested in using electrocardiogram (ECG) signals to analyze the fatigue state of agricultural workers. Healthy agricultural workers were randomly recruited from hilly orchards in South China. Through the field experiment, 130 groups of 5-min interval ECG signals were collected, and we analyzed the ECG signal by HRV. The time domain (meanHR, meanRR, SDNN, RMSSD, SDSD, PNN20, PNN50 and CV), frequency domain (VLF percent, LF percent, HF percent, LF norm, HF norm and LF/HF) and nonlinear parameters (SD1, SD2, SD1/SD2 and sample entropy) were calculated and Spearman correlation coefficient analysis and Mann–Whitney U tests were performed on each parameter for further analysis. For all subjects, nine parameters were slightly correlated in nonfatigue and fatigue state. Six parameters were significantly increased and ten HRV parameters were significantly decreased compared the nonfatigue state. As for males, fifteen parameters were significantly different, and for females, eighteen parameters were significantly different. In addition, the probability density functions of SDNN, SDSD, VLF%, HFnorm and LF/HF were significantly different in nonfatigue and fatigue state for different genders, and the nonlinear parameters become more discrete compared the nonfatigue state. Finally, we obtained the most suitable parameters, which reflect the fatigue characteristics of orchard workers under different genders. The results have instructional significance for identifying fatigue in orchard workers and provide a convincing and valid reference for clinical diagnosis.

Relationship Between Heart Rate Variability and Pulse Rate Variability Measures in Patients After Coronary Artery Bypass Graft Surgery.

Background: Heart rate variability (HRV) and pulse rate variability (PRV) measures are two kinds of physiological indices that can be used to evaluate the autonomic nervous function of healthy subjects and patients with various kinds of illness.Purpose: In this study, we compared the agreement and linear relationship between electrocardiographic signals (ECG)-derived HRV and photoplethysmographic signals (PPG)-derived right hand PRV (R-PRV) and left hand PRV (L-PRV) measures in 14 patients over 1 year after coronary artery bypass graft (CABG) surgery.Method: The ECG and PPG signals of the patient were recorded simultaneously for 10 min in a supine position. The last 512 stationary RR intervals (RRI) and peak-to peak intervals (PPI) of pulse wave were derived for data analysis. Bland-Altman plot was used to assess the agreement among HRV and both hand PRV measures, while linear regression analysis was used to examine the relationship among corresponding measures of HRV, R-PRV, and L-PRV.Result: The results revealed significant differences in total power (TP), very low-frequency power (VLF), low-frequency power (LF), high-frequency power (HF), and normalized VLF (VLFnorm) among HRV, R-PRV, and L-PRV. Bland-Altman plot analysis showed good agreements in almost all measures between R-PRV and L-PRV, except insufficient agreement was found in LF/HF. Insufficient agreements were found in root mean square successive difference (RMSSD), normalized HF (HFnorm), and LF/HF indices between HRV and L-PRV, and in VLFnorm, HFnorm, and LF/HF indices between HRV and R-PRV. Linear regression analysis showed that the HRV, R-PRV, and L-PRV measures were all highly correlated with one another (r = 0.94 ~ 1; p < 0.001).Conclusion: Though PRV measures of either hand are not surrogates of HRV measures, they might still be used to evaluate the autonomic nervous functions of CABG patients due to the moderate to good agreements in most time-domain and frequency-domain HRV measures and the strong and positive correlations among HRV and both hands PRV measures in CABG patients.

Contactless analysis of heart rate variability during cold pressor test using radar interferometry and bidirectional LSTM networks

Contactless measurement of heart rate variability (HRV), which reflects changes of the autonomic nervous system (ANS) and provides crucial information on the health status of a person, would provide great benefits for both patients and doctors during prevention and aftercare. However, gold standard devices to record the HRV, such as the electrocardiograph, have the common disadvantage that they need permanent skin contact with the patient. Being connected to a monitoring device by cable reduces the mobility, comfort, and compliance by patients. Here, we present a contactless approach using a 24 GHz Six-Port-based radar system and an LSTM network for radar heart sound segmentation. The best scores are obtained using a two-layer bidirectional LSTM architecture. To verify the performance of the proposed system not only in a static measurement scenario but also during a dynamic change of HRV parameters, a stimulation of the ANS through a cold pressor test is integrated in the study design. A total of 638 minutes of data is gathered from 25 test subjects and is analysed extensively. High F-scores of over 95% are achieved for heartbeat detection. HRV indices such as HF norm are extracted with relative errors around 5%. Our proposed approach is capable to perform contactless and convenient HRV monitoring and is therefore suitable for long-term recordings in clinical environments and home-care scenarios.

Effect of Left and Right Nostril Breathing on Heart Rate Variability among Healthy Adult Males: A Cross-sectional Study

The effects of various breathing manoeuvres on autonomic functions, especially those of alternate nostrilbreathing and single nostril breathing have been well documented.1,2,3,4 However, most of the studies haveinvestigated these effects after practiced breathing manoeuvres,5,6,7 and few have looked into the immediateeffects of such types of breathing. The purpose of this study was to determine the immediate effects of asingle session of single nostril breathing, first right nostril and then left nostril, on the various time andfrequency domain parameters of heart rate variability (HRV) and to compare these effects with that of HRVduring normal breathing.Sixty male volunteers (age range, 20 to 40 years) were assessed. Electrocardiography was conducted, usingstandard procedure, under controlled laboratory conditions, for three five-minute periods: during breathingnormally through both nostrils, during the last five minutes of a twenty-minute session of breathing throughthe right nostril only and similarly while breathing through the left nostril only. The R-R intervals obtainedwere analyzed for HRV parameters and further analyzed using different statistical method.When compared to right nostril breathing, a statistically significant increase in mean R-R intervals was notedwith left nostril breathing (p = 0.009). Sympathetic activation with right nostril breathing was also evident,although statistically not found to be significant. A statistically significant higher SDNN with left nostrilbreathing as compared to both nostril breathing (p = 0.004) was also observed. Similarly, NN50 and pNN50were found to be significantly higher with left nostril breathing as compared to both nostril breathing (p =0.003 &amp; 0.007, respectively). However, RMSSD, LF power, HF power, LF norm, HF norm and LF/HF ratiowere not found to be statistically different for the three breathing manoeuvres.Thus our study showed an overall parasympathetic predominance, with an increase in total power of HRVwith left nostril breathing, but the minute variations of HRV were not found to be significantly differentamong the three breathing manoeuvres.

Acupuncture for Histamine-Induced Itch: Association With Increased Parasympathetic Tone and Connectivity of Putamen-Midcingulate Cortex.

Previous studies have suggested that acupuncture is effective for ameliorating itch intensity. However, factors associated with the antipruritic effects of acupuncture have yet to be clarified. In a randomized, sham-controlled, crossover trial, we investigated the antipruritic effects of acupuncture against histamine-induced itch in healthy volunteers. Autonomic changes using heart rate variability (HRV) and brain connectivity using functional magnetic resonance imaging (fMRI) were also assessed to identify physiological factors associated with the acupuncture response. Acupuncture significantly reduced itch intensity and skin blood perfusion as assessed by laser Doppler perfusion imaging compared to sham control, indicating the antipruritic effects of acupuncture. In responder and non-responder analysis, the power of normalized high frequency (HF norm) was significantly higher, while the power of normalized low frequency (LF norm) and LF/HF ratio were significantly lower in responders compared to non-responders, suggesting the acupuncture response involved parasympathetic activation. In fMRI analysis, the putamen and the posterior part of the midcingulate cortex (pMCC) were positively connected to itch and negatively correlated with itch intensity in responders. These results suggest that parasympathetic activity and functional connectivity of the putamen and pMCC could be associated with antipruritic response to acupuncture.

ХВИЛЬОВА СТРУКТУРА ГЕМОДИНАМІЧНИХ ПОКАЗНИКІВ В ОСІБ ІЗ РІЗНИМ ВИХІДНИМ РІВНЕМ СЕРЦЕВОГО ВИКИДУ ТА КРОВОНАПОВНЕННЯ ОРГАНІВ ГРУДНОЇ КЛІТКИ

Introduction . Wave fe atures of the duration of cardiointervals (t-R-R) and s troke volume of blood are considered as a reflection of the dynamics of regulatory processes in the body. Significant differences in healthy young men in values of cardiac index and blood supply of the thoracic organs condition on the peculiarities of regulation of the cardiovascular system. Purpose . To find out the peculiarities of the wave structure of oscillations (t-R-R) and s troke volume of blood (SV) in individuals with different baseline cardiac output and blood supply. Methods . The resulting time series were analyzed by 5-min implementations of secuential SV and t-R-R in «Caspico» program . For the duration of the cardiointervals, three main spectral components were distinguished: HF (0.15-0.4 Hz), LF (0.04-0.15 Hz), VLF (0-0.04 Hz), and total spectrum power (TP), the power of high-frequency oscillations in normalized units (HFnorm). For SV, such indicators were HF sv , LF sv , VLF sv , TP sv and HF norm SV , respectively. Results . At rest, the highest t- R - R oscillation power in the LF and HF ranges was established in hypokinetics, the SV oscillation power in the 0.04-0.15 Hz frequency band was significantly higher in hyperkinetics compared to eukinetics, in HF norm SV - it was probably higher in hyperkinetics than hypokinetics. When functional tests were performed, the greatest differences between groups of individuals with different typology by cardiac output were observed at dosed physical activity: HFnorm in hypokinetics was authentically smaller than in the representatives of other groups, LF was larger than in eukinetics, and HF was lower than in hyperkinetics. The initial level of blood supply of the thorax also authentically influenced the peculiarities of oscillations of the hemodynamic indicators of healthy young men under different conditions. At rest in the supine position, individuals with low levels of blood supply of thoracic organs had authentically a higher power of high-frequency oscillations t-R-R than men with an average value of this index, and relatively larger intergroup differences were observed in the parameters of SV oscillations. According to the indicators of the wave structure of t-R-R and SV with active orthopedic testing and with mental load, the lowest activation of the sympathetic nervous system was observed in the group of men with low initial level of blood supply of the thoracic organs. . Originality . The peculiarities of the regulatory rhythms of hemodynamics are revealed in persons with different typology by the level of cardiac output and blood supply of the thoracic organs . Significant differences in the power of oscillations of cardio-interval duration and stroke volume are shown in persons of different types of hemodynamics at rest and at the dosed physical activities. Conclusions . At rest and mainly at physical activity , the features of hemodynamics oscillations have been found between persons with different initial levels of cardiac output, which are of compensatory nature for maintaining cardiac output for hypokinetics, and are caused by different levels of blood supply in the thoracic organs. The wave structure of the regulatory rhythms of hemodynamics and its changes at loads significantly depend on the initial level of blood supply of the thorax , which is shown by the relatively less tension of the mechanisms of regulation in persons of the extreme groups. Taking into account individual-typological characteristics of a person can increase the diagnostic value of methods of analysis and evaluation of the wave structure of hemodynamic parameters, as well as identify new directions in preventive medicine and health insurance.

Cardiac autonomic modulation in response to a glucose stimulus.

This paper focuses on the effect of a sudden increase of plasma glucose concentration in the cardiac autonomic modulation using time-domain and frequency-domain heart rate variability (HRV) measures. Plasma glucose and insulin levels, measured each 30 min during an oral glucose tolerance test, and [Formula: see text] (mean of the RR interval), SDNN (standard deviation of normal-to-normal heartbeats), rMSSD (root-mean-square of successive differences between normal heartbeats), TP (total spectral power), LF and HF (power of the low- and high-frequency bands), LF norm and HF norm (LF and HF in normalized units), and LF/HF ratio of the HRV signal, obtained from 5-min-long ECG recordings during each phase of the test, were analyzed for subjects with the metabolic syndrome, marathon runners, and a control group. Results show that, after the glucose load, subjects with the metabolic syndrome experienced an increased sympathetic and decreased parasympathetic tone, which suggests an imbalance in cardiac autonomic modulation as a consequence of hyperglycemia and hyperinsulinemia. The significance of this study lies in the use of the ECG to assess the effects of a sudden increase in plasma glucose concentration on the cardiac autonomic modulation in subjects with different cardiovascular and metabolic conditions. Graphical Abstract Time-domain and frequency-domain heart rate variability measures are altered in subjects with different cardiovascular and metabolic conditions during an oral glucose tolerance test.

Characteristics of heart rate variability in women with polycystic ovary syndrome: A retrospective cross-sectional study.

We aimed to compare the modulation of the autonomic nervous system (ANS) in women with polycystic ovary syndrome (PCOS) with that in healthy ovulatory women on the basis of heart rate variability (HRV), and to analyze the characteristics of the ANS in PCOS.In a retrospective chart review, HRV, body mass index, and physical examination data in women with PCOS and those with regular menstrual cycles were collected. Approval from the institutional review board (IRB) was obtained (IRB No. 2017-05-007-001) for this study. The mean outcomes were the values of HRV in the time [standard deviation of all normal R-R intervals (SDNN), the square root of the sum of the squares of the differences between the adjacent normal R-R intervals (rMSSD), and the mean heart rate turbulence (mean HRT)] and frequency [total power (TP), very-low-frequency power (VLF), low-frequency power (LF), normalized low-frequency power (LF norm), high-frequency power (HF), normalized high-frequency power (HF norm), and LF/HF ratio] domains. Differences between the 2 groups were analyzed by Mann-Whitney U test, using SPSS for Windows (version 22.0).There was no significant difference in the values of the time domain (SDNN, rMSSD, and mean HRT) between the groups. In the frequency domain, women with PCOS showed significantly higher LF (598.63 ± 94.38 vs 459.13 ± 163.64, P = .028), LF norm (48.64 ± 3.39 vs 36.49 ± 2.82, P = .009), and LF/HF ratio (1.49 ± 0.31 vs 0.73 ± 0.13, P = .009) than the control group. HF norm was significantly lower in the women with PCOS than in the controls (51.38 ± 3.39 vs 63.51 ± 2.82, P = .009). The TP, VLF, and HF showed no significant difference between the groups.The results of the present study indicated that PCOS is related to increased sympathetic modulation in HRV.

Changes in heart rate variability in first-episode drug-naïve adolescents with major depressive disorder: A 12-week prospective study

BackgroundMajor depressive disorder (MDD) is a common mental disorder, the onset of which frequently occurs during adolescence. While differences in heart rate variability (HRV) between depressed and healthy participants have previously been observed, results have been inconsistent. This study thus investigated the features of HRV in adolescents with MDD. MethodsWe recruited first-episode drug-naïve adolescents aged 13–18 years who had been diagnosed with MDD, and healthy age-matched controls. HRV was measured before and after a 12-week antidepressant treatment. We compared HRV measures between patient group and control group. We also tried to find correlation between HRV measures and depression rating scales. ResultsFifty-seven participants were included (patient group: n = 31; control group: n = 26). The patient group showed a lower normalized high frequency (HF norm), a higher normalized low frequency (LF norm), and a higher LF/HF ratio than did the control group. After treatment, LF was significantly decreased within the patient group compared to baseline. Hamilton Depression Rating Scales and Children's Depression Inventory scores were positively correlated with LF norm and LF/HF ratio, and negatively correlated with HF norm, when included all participants in analysis LimitationsSample size of this study was small to assess influences of confounding factors on HRV. And follow up period was relatively short to see impact of pharmacotherapy. ConclusionAn imbalance of the autonomic nervous system might be a meaningful feature of adolescent MDD, and HRV might represent a potential biological marker for pathophysiological changes in MDD.

Maternal Heart Rate Variability during the First Stage of Labor.

Labor necessitates continuous adjustments of cardiac autonomic reflexes by alternate activation of the sympathetic and parasympathetic nervous systems. The division of the autonomic nervous system (ANS) that predominates during the first stage of labor is unclear and needs to be further investigated. The study aimed to compare heart rate variability (HRV) in pregnant women in the third trimester with those during the first stage of labor. We conducted a case–control study at Saad Abul Ela Maternity Hospital, Khartoum, Sudan. Forty-five women with singleton, live neonates in the first stage of labor and 45 women in the third trimester (but not in labor) were enrolled as case and control groups, respectively. Data on the medical history, obstetrics history, and clinical examinations that were performed in all of the studied women were obtained using prearranged questionnaires. Cardiac autonomic modulation (CAM) of the heart was examined in both groups based on time and frequency domain HRV indices. There were no significant differences in age, parity, body mass index, and hemoglobin levels between the two groups. Pregnant women in labor had significantly higher LnSDNN, LnRMSSD, LnTP, LnVLF, LnLF, LnHF, LF Norm, and LnLF/HF ratio, but lower HF Norm compared with controls (P < 0.001). These findings remained unchanged when possible confounders were controlled for using regression analysis. Our findings suggest a significant increase in indictors of sympathetic CAM, namely LF Norm and LnLF/HF, during labor. Sympathetic hypertonia associated with labor is unlikely to increase the risk of cardiac events because sympathetic CAM simultaneously increases with global HRV. Increased HRV during labor may be explained by parasympathetic activation as indicated by higher LnHF and LnRMSSD at the time of delivery.

Comparison Study of Heart Rate Variability at Resting and Real-time Motional States

This study aims to discover the characteristics of heart rate variability of resting and real-time motional states in healthy population. The ECG data of 16 healthy young subjects during 5-minute resting and motion periods were recorded respectively. After that, the R wave was extracted through Hilbert transformation and the RR interval time series was computed. The calculations for HRV parameters in time and frequency domains, Poincaré scatter plots and the detrended fluctuation analysis were conducted. Our study finds that, the measures of real-time motion in time domain (Mean RR, SDNN and RMSSD), the measures in frequency domain (VLF, LF, HF, TP), and the measures of Poincaré scatter plots are significantly less than those of resting state (P <0.001). The measure of long-term fractal exponent (α2) in real-time motion state is significantly higher than resting state (P <0.05). Between the two states, there are no statistically significant differences in other parameters of frequency domain (LF norm, HF norm, LF/HF) and short-term fractal exponent (α1), P>0.05. This study suggests that, the results can provide new characteristic signatures and statistical evidence for sport medicine or rehabilitation medicine.

성조숙 증상을 보이는 여아들의 HRV의 특성 연구

ABSTRACT A Study of the Characteristics of the HRV of the Girl Showing a Precocious PubertySeung-Jeong Yang, Kyung-Mi Park, Seong-Hee ChoDept. of Oriental Gynecology, College of Oriental Medicine, Dong-Shin UniversityObjectives: The aim of the study was to investigate the characteristics of the autonomic innervation of the hea rt in Precocious Puberty (PP) G irls. Methods: We studied 87 girls visiting Dongshin University Suncheon Orie ntal Medicine hospital from first Januarty 2013 to 31th December 201 5. Among the 87 girls who were selected 14 people under the age of 8. The subje cts were categorized in two groups, 2 PP girls and 12 healthy controls. We studied t he difference of Heart rate variability (HRV) between two groups by Independent sample s T-test using SPSS for windows (version 22.0).Results: The Standard deviation of all normal R-R intervals (SDNN), The spuare root of the sum of the spuare of difference between adja cent normal R-R intervals (RMS-SD) of PP group was non-significantly lower than non-PP group.Total power (TP), Very low frequency power (VLF), High frequenc y power (HF), Low frequency power (LF) of PP group was non-significantly lower than non-PP group, LF/HF ratio of PP group was significantly higher than no n-PP group.Normalized high frequency power (HF norm) of PP group was non-s ignificantly lower than non-PP group. Normaliz ed low frequency power (LF nor m) of PP was non-signficantly higher than non-PP group.Conclusion: The results suggest that imbalance of sympathetic and parasymp athetic nervous system from girls of precocious puberty can be seen.Key Words: Precocious Puberty, Heart Rate Variability, Autonomic Nervous System

Digital Infrared Thermal Imaging에 따른 수족냉증 중증도와 Heart Rate Variability의 상관관계 연구

Objectives: Cold Hypersensitivity of Hands and Feet (CHHF) has been diagnosed objectively by Digital Infrared Thermal Imaging (DITI) and has been known to be associated with autonomic nervous system (ANS), which can be assessed by Heart Rate Variability (HRV). This study evaluated the correlation between severity of CHHF and HRV variables.Methods: We studied 155 non-menopausal women with CHHF who visited Kyung Hee University Hospital at Gangdong from 01 October 2013 to 30 April 2016. We measured DITI and HRV of each patient. We used DITI to calculate the severity of CHHF with thermal difference between upper arm (L4, 俠白穴) and palm (P8, 勞宮穴) of both hands and anterior thigh (ST32, 伏兎穴) and dorsum of foot (LI3, 太衝穴) of both feet. The correlation between severity of CHHF and HRV variables were analyzed.Results: In time domain analysis, there was significantly positive correlation between the severity of CHHF and both SDNN and RMSSD. In frequency domain analysis, there was significantly positive correlation between the severity of CHHF and TP, HF and HF Norm while there was significantly negative correlation between the severity of CHHF and LF Norm as well as between the severity of cold hypersensitivity of both hands and LF/HF ratio.Conclusions: The more severe CHHF is, the more increased the function of parasympathetic nerve system (PNS) and relatively decreased the function of sympathetic nerve system (SNS) is. Also, it has known that cold hypersensitivity could be caused by deficiency syndrome and qi deficiency has the same ANS tendency as CHHF. Therefore, in practical fields, this result can be helpful in planning treatment and deciding prognosis in respect of deficiency syndrome.

Exercise induced changes in autonomic nerve function in patients with irritable bowel syndrome by power spectral analysis

Background: Altered autonomic nerve function has been reported by various investigators in IBS and moderate to vigor­ous physical exercise causes autonomic nerve function improvement both in healthy and various clinical conditions. Objective: To observe the effect of brisk walking on the autonomic nerve function by analysis of heart rate in patients with Irritable bowel syndrome.Methods: This prospective interventional study was conducted in the Department of Physiology, Bangabandhu Sheikh Mujib Medical University (BSMMU) between January to December 2013. For this purpose 77 male patients aged 20-50 years with IBS were included in this study, they were enrolled from OPD, Gastroen­terology, BSMMU, Dhaka. For comparison, 28 apparently healthy male were also included as control. HRV measures were recorded once before exercise and also after 3 months of brisk walking. For assessing HRV, frequency domain measures such as total power, LF power, HF power, LF norm and HF norm were recorded by Polyrite D machine. ANOVA, Independent sample t-test and paired t-tests were performed for statistical analysis.Results: The pre-exercise values of HF power, HF norm and total power were significantly lower (p&lt;0.05) whereas values of LF power and LF norm were higher (p&lt;0.05) in all IBS patient compared to those of control. The post exercise data demonstrated signifi­cantly higher (p&lt;0.05) HF power, HF nu and total power in all IBS patients compared to their pre-exercise values.Conclu­sion: This study concluded that the frequency domain measures of HRV were decreased in IBS patients but all these parameters can be improved by regular moderate physical exercise.