Log Low Frequency Research Articles

Uncovering sympathetic nervous system dysfunction in disorders of consciousness via heart rate variability during head-up tilt test.

Few standardized tools are available for evaluation of disorders of consciousness (DOC). The potential of heart rate variability (HRV) during head-up tilt (HUT) test was investigated as a complementary evaluation tool. Twenty-one DOC patients and 21 healthy participants were enrolled in this study comparing clinical characteristics and HRV time- and frequency-domain outcomes and temporal changes during HUT test. During the 1st-5th min of the HUT, DOC group showed a significant increase and decrease in log low frequency (LF) (p = 0.045) and log normalized high frequency (nHF) (p = 0.02), respectively, compared to the supine position and had lower log normalized LF (nLF) (p = 0.004) and log ratio of low-to-high frequency (LF/HF) (p = 0.001) compared to healthy controls. As the HUT continued from the 6th to the 20th min, DOC group exhibited a significant increase in log LF/HF (16th-20th min) (p < 0.05), along with a decrease in log nHF (6th-10th and 16th-20th min) (p < 0.05) and maintained lower log LF, log nLF, and log LF/HF than controls (p < 0.05). 1st-10th min after returning to the supine position, DOC group demonstrated a significant decrease in log nHF (p < 0.01) and increases in log LF/HF (p < 0.01) and had lower log LF (p < 0.01) and log nLF (p < 0.05) compared to controls. In contrast, the control group exhibited a significant decrease in log nHF (p < 0.05) and increase in log LF/HF (p < 0.05) throughout the entire HUT test. Notably, no significant differences were observed when comparing time-domain outcomes reflecting parasympathetic nervous system between the two groups. HRV during HUT test indicated a delayed and attenuated autonomic response, particularly in the sympathetic nervous system, in DOC patients compared with healthy individuals.

Heart Rate Variability in evaluation of autonomic dysfunction in idiopathic REM-sleep behaviour disorder.

Nearly 80% of people diagnosed with idiopathic REM sleep behaviour disorder (iRBD) via video-polysomnography (v-PSG) are expected to be in the prodromal stage of an alpha-synucleinopathy. Signs of autonomic dysfunction can appear earlier than motor or cognitive alpha-synucleinopathy symptoms. Heart Rate Variability (HRV) can potentially be an objective measurement of autonomic dysfunction, and furthermore can be obtained directly from v-PSG. The aim of this study was to evaluate dysautonomia in iRBD subjects using HRV obtained during different sleep stages and wakefulness from v-PSG. Subjects positively screened by an RBD screening questionnaire (RBD-SQ) underwent v-PSG to diagnose RBD. HRV obtained from v-PSG recordings was correlated to dysautonomia evaluated from a Non-Motor Symptoms Scale (NMSS) questionnaire. Optimal cut-off values of HRV parameters to predict dysautonomia were calculated using receiver operating characteristics (ROC) - area under the curve (AUC) analysis. The effect of confounder variables was predicted with binomial logistic regression and multiple regression analyses. Out of 72 positively screened subjects, 29 subjects were diagnosed as iRBD (mean age 66 ± 7.7 years) by v-PSG. Eighty-three per cent of the iRBD subjects in our cohort were at the time of diagnosis classified as having possible or probable prodromal Parkinson's Disease (pPD) compared to zero subjects being positively screened in the control group. The iRBD-positive subjects showed significant inverse correlations of NMSS score, particularly to log low-frequency (LF) component of HRV during wakefulness: r = -0.59 (p = 0.001). Based on ROC analysis and correlation between NMSS score, log LF during wakefulness (AUC 0.74, cut-off 4.69, sensitivity 91.7%, specificity 64.7%, p = 0.028) was considered as the most accurate predictor of dysautonomia in the iRBD group. Apnoea-hypopnoea index (AHI) negatively predicted dysautonomia in the iRBD group. None of the HRV components was able to predict the presence of iRBD in the full cohort. Age, gender, and PSG variables were significant confounders of HRV prediction. The presented study did not confirm the possibility of using HRV from v-PSG records of patients with iRBD to predict dysautonomia expressed by questionnaire methods. This is probably due to several confounding factors capable of influencing HRV in such a cohort.

Evaluation of Fatigue in Cancer Patients in An Area Affected by the Great East Japan Earthquake

Objective:The objective of this study is to evaluate fatigue in cancer outpatients receiving chemotherapy using an objective system and to clarify the type of nursing support needed after a disaster.Methods:Based on the diagnostic criteria for chronic fatigue syndrome, the degree of subjective fatigue, autonomic function, and amount of physical activity were measured in cancer outpatients undergoing chemotherapy from an area affected by the Great East Japan Earthquake.Results:The study participants were ten adults (8 men [80.0%] and 2 women [20.0%]). Significant differences were seen in subjective physical fatigue (P = 0.347), mental fatigue (P = 0.128), comprehensive fatigue (P = 0.621), and comprehensive evaluations (P = 0.293); however, no significant differences were seen in the results for changes over time for any survey item. The balance between sympathetic and parasympathetic nerve function changed statistically significant with time (log low frequency [LF] [P = 0.039] and log LF/high frequency [HF] [P = 0.021]). In all participants, autonomic nervous function was enhanced in the sympathetic nervous system, and the sympathetic nervous system was dominant. Significant differences were observed between the three measurements for mean diurnal activity (P = 0.027), total sleep time (P = 0.011), sleep efficiency (P = 0.019), awakening (P = 0.032), and naps (P = 0.037).Conclusions:In the event of a disaster, in addition to self-care support for side effects caused by anticancer drugs, patients' physical and mental conditions are assessed in terms of fatigue using objective indicators, and then, appropriate nursing support is provided. The nurse grasps objective facts behind the patient's subjective data and systematically recommends adjustments to the patient's daily life. In addition, by providing appropriate information to patients, patient education specific to each patient is provided.

Happiness at Your Fingertips: Assessing Mental Health with Smartphone Photoplethysmogram-Based Heart Rate Variability Analysis.

Background: Heart rate variability (HRV) provides essential mental health information for clinical diagnosis, telemedicine, preventive medicine, and public health; however, the lack of a convenient detection method limits its potential. Objective: This study aims to investigate the feasibility and credibility of smartphone photoplethysmogram (PPG)-based HRV analysis for mental well-being and health assessment. Methods: Data were collected from 93 students and university employees in Shenzhen, China. Forty-six percent were male, and the average age was 23.71 years (σ = 4.33). An app recorded a 4-min video of their fingertips and converted the frames into five HRV measures, including the root mean square of successive differences (rMSSD), standard deviation of the normal-to-normal (NN) intervals (SDNN), percentage of successive NN intervals differing by ≥50 ms (pNN50), log high-frequency (HF) HRV, and log low-frequency (LF) HRV. Results: The data verify the positive relationship between mental well-being and HRV measures. Participants with higher Satisfaction With Life Scale (SWLS) scores have a higher rMSSD (p = 0.047), SDNN (p = 0.009), log HF (p = 0.02), and log LF (p = 0.003). Participants who suffer from depression have lower log HF (p = 0.048) and log LF (p = 0.02). Participants in the high-anxiety group have lower pNN50 (p = 0.04) and log HF (p = 0.03). Conclusions: The results of this study validate the feasibility of using the smartphone PPG by demonstrating similar results to previous findings. Our data also support the theorized positive link between mental health and HRV.

Clinical utility of heart rate variability during Head-up tilt test in subjects with chronic posttraumatic stress disorder

Posttraumatic stress disorder (PTSD) is characterized by psychophysiological abnormalities, such as an altered baseline heart rate and hyperarousal, implying dysfunctional arousal regulation. Heart rate variabilities (HRVs) is known to reflect autonomic nervous system activity. We examined the changes of HRVs in PTSD patients with head-up tilt position to closely investigate disease-specific changes in autonomic function in PTSD patients. Sixty-seven patients with PTSD and 72 patients without PTSD were assessed using the PTSD Checklist for DSM-5 (PCL-5) and psychiatric interview. Heart rate data including standard deviation of the NN intervals, the square root of the mean squared differences of successive NN intervals, log low-frequency and log high-frequency were collected for 10 min before and after tilting. Considering interactions between groups and head-up tilting, the head-up tilting induced reduction of the high-frequency component of HRVs was significantly greater in the PTSD group [F (1, 272) = 4.718, p = 0.031]. The change of HRVs in PTSD patients suggested the presence of autonomic dysfunction in despite of the posture.

Nutraceutical Properties of Bangladeshi Rice Varieties

Objectives: Prevalence of subclinical vitamin B12 deficiency is high during early pregnancy especially among Indian women. Early pregnancy is also associated with modulations in autonomic nervous activity to adapt to haemodynamic changes. Current study aimed to compare the autonomic nervous activity through heart rate variability (HRV) indices during early pregnancy in women with low and high vitamin B12 status. Methods: Forty-two healthy pregnant Indian women in their early pregnancy (<14 weeks) were evaluated. Blood samples were analysed for plasma vitamin B12, haemogram and ECG. ECG was subjected to heart rate variability analysis. Subjects were divided into four groups based on quartile values of vitamin B12 levels. Results: There was a significant difference in Log LF (low frequency) HRV between the study groups (p=0.03). Log LF HRV was lower in lowest vitamin B12 group (Quartile 1 of Vitamin B12 levels 248.7 pmol/L) (p=0.05). There was a significant positive correlation between plasma vitamin B12 levels and Log LF (r=0.36, p=0.02). Conclusion: This study showed reduced sympathetic activity among subjects with low vitamin B12 status compared to subjects with high vitamin B12 status. Thus, emphasising the use of vitamin B12 levels during routine clinical evaluation and utility of simple measures like HRV as a screening tool during pregnancy along with postural blood pressure evaluation to rule out orthostatic intolerance. Further, longitudinal studies are required to evaluate vitamin B12 status and its long-term impact on autonomic nervous system during pregnancy.

Nutraceutical Properties of Bangladeshi Rice Varieties

Objectives: Prevalence of subclinical vitamin B12 deficiency is high during early pregnancy especially among Indian women. Early pregnancy is also associated with modulations in autonomic nervous activity to adapt to haemodynamic changes. Current study aimed to compare the autonomic nervous activity through heart rate variability (HRV) indices during early pregnancy in women with low and high vitamin B12 status. Methods: Forty-two healthy pregnant Indian women in their early pregnancy (<14 weeks) were evaluated. Blood samples were analysed for plasma vitamin B12, haemogram and ECG. ECG was subjected to heart rate variability analysis. Subjects were divided into four groups based on quartile values of vitamin B12 levels. Results: There was a significant difference in Log LF (low frequency) HRV between the study groups (p=0.03). Log LF HRV was lower in lowest vitamin B12 group (Quartile 1 of Vitamin B12 levels 248.7 pmol/L) (p=0.05). There was a significant positive correlation between plasma vitamin B12 levels and Log LF (r=0.36, p=0.02). Conclusion: This study showed reduced sympathetic activity among subjects with low vitamin B12 status compared to subjects with high vitamin B12 status. Thus, emphasising the use of vitamin B12 levels during routine clinical evaluation and utility of simple measures like HRV as a screening tool during pregnancy along with postural blood pressure evaluation to rule out orthostatic intolerance. Further, longitudinal studies are required to evaluate vitamin B12 status and its long-term impact on autonomic nervous system during pregnancy.

Subclinical Vitamin B12 Deficiency and Heart Rate Variability Across Life Cycle.

The present study aimed to evaluate association between plasma vitamin B12 and heart rate variability in clusters of population of various ages across life cycle. 47 healthy children from an ongoing pregnancy and birth cohort, 32 young adults and 47 healthy elderly subjects were recruited following inclusion and exclusion criteria. All subjects underwent plasma vitamin B12, anthropometry and heart rate variability (HRV). The prevalence of vitamin B12 deficiency (&lt;148 pmol/l) across age groups were 51.1 % for children, 56.2 % for young adults and 61.7 % for the elderly group respectively. There was large variability in vitamin B12 status across the age groups. Frequency distribution of low frequency (LF) absolute units HRV in the elderly was skewed, whereas in children and young adult group there was wide distribution of LF HRV. Association between Log LF absolute units HRV and plasma vitamin B12 across groups were tested using curve fit models. In children a linear curve estimation best fitted and explained 9.3 % of the association (n=47, .=0.003, P=0.03, R2=0.09). There was no association between log LF absolute units HRV and plasma vitamin B12 in the young adult group. In the elderly group a power curve fit model best fitted and explained 8.9 % of the association. Inspection of the power curve fit model demonstrated a curvilinear pattern; there was a linear association in the elderly with vitamin B12 levels less than 200 pmol/l. However, elderly with vitamin B12 values &gt;200 pmol/l demonstrated saturation (plateauing) of log LF HRV. The study demonstrated varied pattern of responses between vitamin B12 status and LF power of HRV across age groups. Thus, it is important to consider these associations before planning supplementation of vitamin B12.

Gene Polymorphism of the Adenosine A2a Receptor in Patients with Vasovagal Syncope.

Adenosine may play a role in the pathogenesis of vasovagal syncope (VVS). The aim of the study was to evaluate the adenosine A(2A) receptor gene 1083 T > C polymorphism in patients with syncope and its possible association with results of head-up tilt test (HUT). Three hundred and forty-seven consecutive patients (mean age 47.3 ± 18.5 years, 132 men, 215 women) with one or more syncopal episodes underwent HUT as part of standardized diagnostic evaluation. HUT was positive in 207 patients (75 males, mean age 44.7 ± 18.6 years) and negative in 140 patients (58 males, mean age 48.17 ± 18.8 years). One thousand and eighty-three T > C single nucleotide polymorphism in the adenosine A(2A) receptor gene (rs5751876) was evaluated in 347 patients with syncope and in 85 subjects without history of syncope (54 men, mean age 41.7 ± 16.3). Adenosine A(2A) receptor 1083 T > C polymorphism was not associated with the positivity of HUT. Blood pressure and heart rate response to tilting was similar in all genotypes. Low frequency (LF) power was significantly lower in CC genotype compared to CT genotype in early phase of tilt (log LF 2.69 ± 0.61 vs 3.20 ± 0.60; P = 0.01) and at the time of syncope (log LF 2.60 ± 0.63 vs 2.77 ± 0.48; P = 0.04). Adenosine A(2A) receptor 1083 T > C polymorphism is not associated with the positivity of HUT and its proposed role in predisposition to VVS was not confirmed. CC genotype may be associated with lower sympathetic activity during HUT.

Randomized controlled trial of heart rate variability biofeedback in cardiac autonomic and hostility among patients with coronary artery disease

Hostility is a psychosocial risk factor that may decrease heart rate variability (HRV) in coronary artery disease (CAD) through cardiac autonomic imbalance. Heart rate variability biofeedback (HRV-BF) increases HRV indices and baroreflex gain. This study examines the effectiveness of HRV-BF in restoring cardiac autonomic balance and decreasing hostility among patients with CAD. One hundred and fifty-four patients with CAD were assigned randomly to receive 6 weeks of HRV-BF, in addition to the standard medical care received by the wait-list control (WLC) group. A 5-min electrocardiogram, blood pressure, and hostility were assessed pre-intervention, post-intervention, and at 1-month follow-up. The standard deviation of normal-to-normal intervals (SDNN), low frequency (LF), and log LF at post-intervention was significantly higher than that at pre-intervention in the HRV-BF group. Baseline log LF was significantly higher post-intervention and at follow-up after HRV-BF training than at pre-intervention. The treatment curve of log LF pre-session increased significantly after session 2, which was maintained to post-intervention. Expressive hostility, suppressive hostility, and hostility total score at post-intervention and one-month follow-up after HRV-BF were significantly lower than at pre-intervention. This study showed increased HRV and decreased expressive and suppressive hostility behavior in patients with CAD following HRV-BF.

Heart Rate Regulation Processed Through Wavelet Analysis and Change Detection: Some Case Studies

Heart rate variability (HRV) is an indicator of the regulation of the heart, see Task Force (Circulation 93(5):1043-1065, 1996). This study compares the regulation of the heart in two cases of healthy subjects within real life situations: Marathon runners and shift workers. After an update on the state of the art on HRV processing, we specify our probabilistic model: We choose modeling heartbeat series by locally stationary Gaussian process (Dahlhaus in Ann Stat 25, 1997). HRV is then processed by the combination of two statistical methods: (1) Continuous wavelet transform for calculating the spectral density energy in the high frequency (HF) and low frequency (LF) bands and (2) Change point analysis to detect changes of heart regulation. Next, we plot the variations of the HF and LF energy in extreme conditions for both populations. This puts in light, that physical activities (rest, moderate sport, marathon race) can be ordered in a logical continuum. This allows to define a new index based on HF and LF energy that is log HF + log LF which appears relevant to measure HR regulation. The results obtained are pertinent but have to be completed by further studies.

Heart Rate Recovery after Exercise and Cardiac Autonomic Nervous Activity in Children

To investigate the difference in heart rate (HR) recovery after exercise between children and young adults, we administered a constant load of light exercise intensity and progressive treadmill exercise tests to nine children (aged 9 to 12 y, group A) and eight young adults (six male and two female, aged 17 to 21 y, group B) who had a history of Kawasaki disease without significant coronary arterial lesions. HR after both exercise protocols was analyzed. The low-frequency (LF) and high-frequency (HF) components of HR variability were measured, and LF/HF was calculated (log LF, log HF, log L/H). Arterial baroreflex sensitivity was assessed by the phenylephrine method. There were no differences between groups A and B in resting HR, peak HR, peak oxygen uptake, and decreases in systolic blood pressure during the recovery period. HR 1 and 2 min after peak exercise and 1 min after constant-load exercise was significantly lower in group A than in group B (p < 0.05), and the changes in HR from peak values after both exercise tests were also greater in group A than in group B (p < 0.05-0.01). Although no difference in arterial baroreflex sensitivity was observed, log HF was significantly higher in group A than in group B (p < 0.01), and log L/H was significantly lower in group A than in group B (p < 0.05). The value of log HF correlated inversely with the decrease in HR immediately after both exercise protocols (p < 0.05-0.01). Although log L/H correlated with the decrease in HR after peak exercise (p < 0.05-0.0005), the early decline in HR after constant-load exercise did not correlate with log L/H. Arterial baroreflex sensitivity did not correlate with the decrease in HR at any recovery time. These data suggest that the early phase of HR recovery after light to severe exercise is influenced by the cardiac parasympathetic nervous activity at rest and that the greater central cholinergic modulation of HR in children than in young adults may be responsible in part for children's faster HR recovery after exercise.