Heart rate variability in the fetus: a comparison of measures

Characterisation of cardiac autonomic function in multiple sclerosis based on spontaneous changes of heart rate and blood pressure

Studies have assessed changesin autonomic variables in terms of heart rate variability (HRV) during meditation, but their results have been conflicting. Recently, Telles and colleagues’ excellent study 1 compared changes in HRV measures during the first four meditative states—cancalata (random thinking), ekagrata (nonmeditative focusing), dharana (meditative focusing), and dhyana (effortless meditation)— described in traditional yoga texts. Their results revealed that the discrepancy in changes in HRV measures might be due to the different stages. At the end of the Discussion section, the authors mention the ultimate state in yoga, samadhi, which manifests with breath suspension. They did not explore this advancedmeditativestateintheirstudy.Therefore,wewould like to share our results about changes in HRV measures during breath suspension. We collected and compared HRV measures in time and frequency domains, along with heart rate and blood pressure, during random thinking, breath meditation, and the advanced meditative stage with breath suspension in 10 meditative sessions conducted by an experienced meditator. The results (Table 1) show that none of HRV measures of time and frequency domains differed significantly during meditation. In contrast, heart rate and systolic blood pressure reliably decreased as meditation advanced. Because the meditation technique used in this study is close to meditative focusing, the results are concordant with the dharana state described in Telles and colleagues’ study. By using a device to monitor the chest circumstance of the meditator, the current study confirmed that the timing of breath suspension coincided with the subjective experience of breath suspension, complete quiescence, and absence of self-boundary. HRV measures, on the other hand, did not concord with the subjective experience of pure quiescence. Because other authors have argued that HRV is not an index of autonomic control of the circulation, 2 whether HRV can be an ideal index of sympathetic or parasympathetic activities remains questionable. According to the current results, the variations of HRV measures, manifested as the ratio of standard deviation to mean, are much greater than those of heart rate and blood pressure. This has also been shown in previous studies. 1,3,4 According to this view, HRV measures cannot be accurate indexes. The current results suggest that heart rate itself is a better HRV measure for meditation and agree with findings from Mukherjee et al. 5 These authors examined the sensitivity to mental effort and reliability of various HRV measures. Their

1 Anu Muraja‐Murro, 1 Ari Pääkkönen, 2 Leena Jutila, 2 Reetta Kälviäinen, 3 Arto Immonen, 1 Sara Määttä, and 1 Esa Mervaala ( 1 Clinical Neurophysiology, Kuopio University Hospital, University of Kuopio, Kuopio, Finland ; 2 Neurology, Kuopio University Hospital, University of Kuopio, Kuopio, Finland ; and 3 Neurosurgery, Kuopio University Hospital, University of Kuopio, Kuopio, Finland ) Rationale: Mismatch‐negativity (MMN) is an auditory event‐related potential (ERP) produced by a deviant stimuli that occurs infrequenty among standard stimuli. MMN is thought to reflect the activation of an automatic change‐detector system that compares new auditory input with a short‐term memory trace generated by the previous auditory stimuli. MMN in human has been demonstrated from several cortical sites, but not to our knowledge from hippocampus or amygdala. This is surprising, given that these limbic structures are so essential for learning and memory functions. We could obtain MMN from these temporomesial structures using intracranial electrodes in adult patients undergoing presurgical evaluation for epilepsy surgery. Methods: 4 adults with intractable temporal lobe seizures (age 32–48 years) had each 2–4 stereotactically implanted 6‐contact depth‐electrodes at amygdalo‐hippocampal complex. The electrodes were implanted via lateral approach and their exact anatomical localizations were confirmed by MRI and CT in situ. After the post hoc anatomical localization of the depth‐electrodes, the presence of MMN could be studied from 6 hippocampi and 5 amygdalas (i.e., the electrode tips were exactly within amygdalo‐hippocampal complex). The most mesial depth‐electrode contacts were chosen for the MMN analysis with the MMN latency range of 120–250 ms, as well as with the P300 range of 250–500 ms. We analyzed possible statistically significant differences between the ERPs to deviant and standard tones. Results: A definite MMN within 120–250 ms latency range could be recorded from 4/6 hippocampi and 3/5 amygdalas. MMN was also detected within 250–500 ms latency range in 3/6 hippocampi and 2/5 amygdalas, respectively. In only one patient the hippocampal MMN resembled typical scalp‐recorded MMN. In all, the MMN decreased from the deepest contacts towards the cortex, suggesting a local maximum of MMN at the amygdalo‐hippocampal complex. Conclusions: Our data implicates that a local and early (120–500 ms post‐stimuli) automatic electrophysiological change‐detector system exists within the amygdalo‐hippocampal complex. This data is the first to demonstrate that also these temporomesial structures are activated and involved in mismatch detection, and is in line with recent sensory mismatch fMRI studies. Other sensory stimuli might also produce MMN in the same structures, possibly thus revealing a common function for hippocampus and amygdala in early sensory stimulus detection. 1 Tobias Loddenkemper, 2 Gabriel Moeddel, 1 Elia M. Pestana, 1 Deepak K. Lachhwani, 1 Ajay Gupta, 1 Prakash Kotagal, and 1 Elaine Wyllie ( 1 Department of Epilepsy and Sleep Disorder, The Cleveland Clinic Foundation, Cleveland, OH ; and 2 Department of Neurology, Universitaetsklinikum Muenster, Muenster, Westfalen, Germany ) Rationale: The intracarotid amobarbital test (IAT) is part of the presurgical workup of patients scheduled for epilepsy surgery to determine language and memory lateralization. Most information on results and complications are derived from adults. Little is known about children undergoing IAT. Difficulties arise from anxiety, need for barbiturate dosage adjustment, and impaired baseline memory in children with mental retardation [4]. The goal of this study was 1) to describe language lateralization in children with epilepsy and 2) to outline complications during IAT. Methods: 126 consecutive pediatric IAT performed at the Cleveland Clinic Foundation during a seven year period were reviewed. Results: 44 patients were age 5–12 years, 82 were age 13–18. 102 were right‐handed. Amobarbital (n = 96, average dose: 100 +‐ 25 mg) or Methohexital (n = 30, average dose 5 +‐ 1 mg) was injected into the left (n = 18), right (n = 13), or both (n = 95) ICA. Language was localized in 95 patients (75.4%): 75 [78.9%] were left, 6 [6.3%] were right, 14 [14.7%] bilateral language dominant. Neurological complications included prolonged lethargy impairing language and memory evaluation in 4 patients. Four children had a seizure after injection. Additionally, valid data could not be obtained due to fear or agitation in three children age 5–9 years. No lasting neurological deficits were seen. General complications included shortness of breath after contrast injection in one boy. One girl presented with fever of 38.5 C the night after the procedure complaining of groin pain. No other major complications were seen. Conclusions: This is one of the largest pediatric IAT series studied so far. The data on language lateralization agree with those previously reported [1, 2, 3]. The IAT in children is an invasive test with a potential for complications, as in adults, occuring in 10 out of 126 patients [7.9%]. Our series highlights the need for refinement and further development of novel methods to establish language lateralization in children during the evaluation for epilepsy surgery. REFERENCES 1. Loring D et al : . Neuropsychologia 28/8 ( 1990 ): 831 – 938 . 2. Mateer CA , Dodrill CB : . Hum Neurobiol 2 ( 1983 ): 135 – 142 3. Strauss E , Wada J : . Cortex 19 ( 1983 ): 165 – 177 ). 4. Szabo CA , Wyllie E : . Epilepsy Res 15 () ( 1993 ): 239 – 246 1 Eija Ronkainen, 1 Juha T. Korpelainen, 2 Heikki V. Huikuri, 1 Vilho V. Myllylä, and 1 Jouko I.T. Isojärvi ( 1 Department of Neurology, University of Oulu, Oulu, Finland ; and 2 Department of Internal Medicine, Division of Cardiology, University of Oulu, Oulu, Finland ) Rationale: To prospectively evaluate changes in interictal heart rate (HR) variability in patients with temporal lobe epilepsy (TLE) after 4 years follow‐up. Methods: A 24‐hour ECG recording was obtained at baseline and four years after first record

Measurement of heart rate variability can reveal autonomic nervous system function. Changes in heart rate variability can be associated with disease severity, risk of complications, and prognosis. We aimed to investigate the prognostic value of heart rate variability measurements in patients with moderate-to-severe traumatic brain injury after decompression surgery. We conducted a prospective study of 80 patients with traumatic brain injury after decompression surgery using a noninvasive electrocardiography device for data collection. Assessment of heart rate variability parameters included the time and frequency domains. The correlations between heart rate variability parameters and one-year mortality and functional outcomes were analyzed. Time domain measures of heart rate variability, using the standard deviation of the RR intervals and the square root of the mean squared differences of successive RR intervals, were statistically significantly lower in the group of patients with unfavorable outcomes and those that died. In frequency domain analysis, very low-frequency and total power were significantly higher in patients with favorable functional outcomes. High-frequency, low-frequency, and total power were statistically significantly higher in patients who survived for more than one year. Multivariate analysis using a model combining age and the Glasgow Coma Scale score with variables derived from heart rate variability substantially improved the prognostic value for predicting long-term outcome. These findings reinforced the concept that traumatic brain injury impacts the brain-heart axis and cardiac autonomic modulation even after decompression surgery, and variables derived from heart rate variability may be useful predictors of outcome.

In heart rate variability (HRV) measurement, a Holter monitor is typically used to observe ECG data. However, since this device lacks mobility, any alternative wearable devices with a similar capability of recording cardiac data are preferred. On the other hand, the application provided alongside wearable devices are mostly installed in smartphone environments, which cause significant concern in user's privacy. It is better to develop our application to calculate sensitive data. This study proposed an application that utilizes a commercialized wearable wireless device to collect electrocardiography data and performs an HRV measurement using time domain, frequency domain, and nonlinear domain. Furthermore, it also examines RR interval and ECG data produced by Polar H10. This study is done by prototyping and experimenting involving participants in a laboratory environment. As a result, the proposed application successfully extracts several pieces of information based on HRV measurement. Using T-test shows data RR interval data and ECG data produced by Polar H10 are equal. Thus, RR interval data is suggested for HRV measurement instead of ECG data from the device. Because in ECG data produced by Polar H10 consist of noise especially in early recording. The benefit of using this application is the ability to conducting real-time and continuous measurement cardiac data based on HVR methods.

Heart rate variability (HRV) has been used to investigate the autonomic modulation of heart rate. Diminished HRV has been observed in diabetic autonomic neuropathy, a condition associated with increased mortality. Uraemia is associated with impaired autonomic function, but reports on the effects of uraemia on HRV are scarce. HRV and its circadian variation were studied in 12 diabetic and 11 non-diabetic renal transplantation and in 12 control patients. HRV in time and frequency domains was determined from 24-hour ECG recordings. In the diabetic group, all time domain and frequency domain measures of HRV were markedly reduced (P < 0.05), when compared with the control group, and the circadian variation of HRV was absent. The mean (SD) amplitudes (ms) in the frequency bands were: high frequency: 3 (1), 6 (3) and 15 (3); low frequency: 9 (7), 16 (10) and 25 (8); very low frequency: 14 (8), 23 (12) and 30 (11) in the diabetic and non-diabetic uraemic and in the control patients, respectively. In non-diabetic uraemic patients, a tendency to reduced HRV was observed, but no statistical differences in HRV measures were found when compared with the control group. The severe impairment of HRV in patients with end-stage diabetic nephropathy is probably due to autonomic neuropathy and partly also to the co-existing heart diseases. It may be a contributing risk factor for ventricular arrhythmias and sudden death in these patients. Uraemia alone causes similar but less severe changes in HRV.

BackgroundSex differences and causality of the association between heart rate variability (HRV) and atrial fibrillation (AF) in the general population remain unclear.Methods12,334 participants free of AF from the population-based Rotterdam Study were included. Measures of HRV including the standard deviation of normal RR intervals (SDNN), SDNN corrected for heart rate (SDNNc), RR interval differences (RMSSD), RMSSD corrected for heart rate (RMSSDc), and heart rate were assessed at baseline and follow-up examinations. Joint models, adjusted for cardiovascular risk factors, were used to determine the association between longitudinal measures of HRV with new-onset AF. Genetic variants for HRV were used as instrumental variables in a Mendelian randomization (MR) analysis using genome-wide association studies (GWAS) summary-level data.ResultsDuring a median follow-up of 9.4 years, 1302 incident AF cases occurred among 12,334 participants (mean age 64.8 years, 58.3% women). In joint models, higher SDNN (fully-adjusted hazard ratio (HR), 95% confidence interval (CI) 1.24, 1.04–1.47, p = 0.0213), and higher RMSSD (fully-adjusted HR, 95% CI 1.33, 1.13–1.54, p = 0.0010) were significantly associated with new-onset AF. Sex-stratified analyses showed that the associations were mostly prominent among women. In MR analyses, a genetically determined increase in SDNN (odds ratio (OR), 95% CI 1.60, 1.27–2.02, p = 8.36 × 10–05), and RMSSD (OR, 95% CI 1.56, 1.31–1.86, p = 6.32 × 10–07) were significantly associated with an increased odds of AF.ConclusionLongitudinal measures of uncorrected HRV were significantly associated with new-onset AF, especially among women. MR analyses supported the causal relationship between uncorrected measures of HRV with AF. Our findings indicate that measures to modulate HRV might prevent AF in the general population, in particular in women.Graphical abstractAF; atrial fibrillation, GWAS; genome-wide association study, IVW; inverse variance weighted, MR; Mendelian randomization, MR-PRESSO; MR-egger and mendelian randomization pleiotropy residual sum and outlier, RMSSD; root mean square of successive RR interval differences, RMSSDc; root mean square of successive RR interval differences corrected for heart rate, SDNN; standard deviation of normal to normal RR intervals, SDNNc; standard deviation of normal to normal RR intervals corrected for heart rate, WME; weighted median estimator.aRotterdam Study n=12,334bHRV GWAS n=53,174cAF GWAS n=1,030,836

To assess heart-rate variability (HRV) measures of interictal electrocardiography (ECG) for drug-resistant epilepsy and to relate the findings to the outcome of vagus nerve stimulation (VNS) treatment. Time-domain, frequency-domain, and nonlinear analyses were used to analyze preoperative HRV measures in 32 patients with drug-resistant epilepsy who had received VNS implants at the same hospital and 32 healthy age- and sex-matched control subjects. HRV measurements based on ambulatory 24h ECG recordings were analyzed to identify seizure reduction 1year after VNS treatment. Responders were defined as having at least 50% seizure reduction 1year after treatment. Patients with drug-resistant epilepsy had significantly lower time domain (SDNN, RMSSD, pNN50), frequency domain (VLF, LF, HF, TP), and nonlinear (SD1, SD2) HRV measurements than matched healthy controls. None of the analyzed HRV measures of the responders differed significantly from their controls, whereas those of the nonresponders had significantly lower RMSSD, pNN50, HF, and SD1 than the responders. The preoperative HRV indices demonstrate that nonresponders have more pronounced impairment of their cardiac autonomic function than the responders. Presurgical HRV measurements representing parasympathetic cardiac control or vagal tone were significantly associated with the responsiveness to VNS. Thus the measurements show promise for predicting the reduction of seizure frequency after VNS treatment.

Power spectral analysis of fetal heart rate variability has been proposed to provide a non-invasive estimate of autonomic balance. However, there are few systematic data before birth. We therefore examined developmental changes in the frequency power spectrum at very low (0-0.04 Hz), low (0.04-0.15 Hz) and high frequencies (0.15-0.4 Hz), as well as the ratio of low- to high-frequency power (LF/HF), in chronically catheterized, healthy fetal sheep at 0.6 (n = 8), 0.7 (n = 7) and 0.8 gestational age (ga; n = 11). In a second study, 0.8 ga fetuses received either atropine (4.8 mg bolus, then 4.8 mg h(-1) for 30 min, n = 6) or 6-hydroxydopamine (20 mg ml(-1) at 2.5 ml h(-1) for 3 h; n = 9). Data were analysed by sleep state, defined by low-voltage-high-frequency (LV) or high-voltage-low-frequency (HV) EEG. Total spectral power increased with gestational age (P < 0.05), while LF/HF decreased from 0.6 to 0.7 ga. At 0.8 ga, heart rate and LF/HF were significantly higher during HV than LV sleep (P < 0.05). Consistent with this, although total spectral power was not significantly greater during HV sleep, there was a significant interaction between sleep state and frequency band (P = 0.02). Both atropine (P = 0.05) and 6-hydroxydopamine (P < 0.05) were associated with an overall reduction in spectral power but no significant effect on the LF/HF ratio. This study does not support substantial, consistent differences between the frequencies of sympathetic and parasympathetic activity in late-gestation fetal sheep.

Objective:This study aims to evaluate the features of heart rate variability (HRV) and respiratory signals as indices for a driver"s drowsiness and waking status in order to develop the classification model for a driver"s drowsiness and waking status using those features. Background: Driver"s drowsiness is one of the major causal factors for traffic accidents. This study hypothesized that the application of combined bio-signals to monitor the alertness level of drivers would improve the effectiveness of the classification techniques of driver"s drowsiness. Method: The features of three heart rate variability (HRV) measurements including low frequency (LF), high frequency (HF), and LF/HF ratio and two respiratory measurements including peak and rate were acquired by the monotonous car driving simulation experiments using the photoplethysmogram (PPG) and respiration sensors. The experiments were repeated a total of 50 times on five healthy male participants in their 20s to 50s. The classification model was developed by selecting the optimal measurements, applying a binary logistic regression method and performing 3-fold cross validation. Results: The power of LF, HF, and LF/HF ratio, and the respiration peak of drowsiness status were reduced by 38%, 22%, 31%, and 7%, compared to those of waking status, while respiration rate was increased by 3%. The classification sensitivity of the model using both HRV and respiratory features (91.4%) was improved, compared to that of the model using only HRV feature (89.8%) and that using only respiratory feature (83.6%). Conclusion: This study suggests that the classification of driver"s drowsiness and waking status may be improved by utilizing a combination of HRV and respiratory features. Application: The results of this study can be applied to the development of driver"s drowsiness prevention systems.

RCT evidence on methods of induction of labour for women with a prior caesarean section is inadequate, and studies are underpowered to detect clinically relevant differences for many outcomes. Several studies reported few of our prespecified outcomes and reporting of infant outcomes was especially scarce. The GRADE level for quality of evidence was moderate to very low, due to imprecision and study design limitations.High-quality, adequately-powered RCTs would be the best approach to determine the optimal method for induction of labour in women with a prior caesarean birth. However, such trials are unlikely to be undertaken due to the very large numbers needed to investigate the risk of infrequent but serious adverse outcomes (e.g. uterine rupture). Observational studies (cohort studies), including different methods of cervical ripening, may be the best alternative. Studies could compare methods believed to provide effective induction of labour with low risk of serious harm, and report the outcomes listed in this review.

E3-1 Axonal growth and synaptogenesis

Non-invasive positive pressure ventilation (NIPPV) is known to enhance hypoventilation and is particularly adopted as a treatment for patients diagnosed with obesity hypoventilation syndrome (OHS). The augmented risk of cardiovascular morbidity is known as a side effect of OHS. In this paper, this inference is examined that hypoventilation and the increased risk of morbidity can be diagnosed via the assessment of changes in heart rate variability (HRV). More specifically, the study investigates the effect of NIPPV on both HRV and hypoventilation among OHS patients. The linear relationship between different HRV measures and ventilation parameters is also examined. The reported results are attained via an interventional clinical trial study. HRV measures are evaluated before and after treatment, in a group of patients which are newly diagnosed with OHS and receive bi-level positive airway pressure (BiPAP) treatment for three months. The results are compared and interpreted via statistical analysis. Throughout the study, the relationship between hypoventilation and HRV is confirmed, as well as the effect of BiPAP on some HRV measures in both time and frequency domains. Particularly significant connections are observed between hypoventilation and low-frequency components of HRV. The enhanced respiration due to the application of BiPAP can improve the performance of autonomous nervous and cardiovascular systems, in terms of HRV. Moreover, it is suggested to consider some HRV parameters to control the cardiovascular side-effects of OHS and confine the resulting mortality rate in long term.

Background and Objectives: Postoperative atrial fibrillation (AF) is a frequent complication after coronary artery bypass grafting (CABG), and is particularly associated with poor outcomes. Heart rate variability (HRV), a non-invasive marker of autonomic function, has been proposed as a tool to predict AF risk, but its utility in off-pump CABG remains unclear. This study aimed to evaluate the predictive value of preoperative HRV parameters, including nonlinear metrics, for postoperative AF in patients undergoing off-pump CABG. Materials and Methods: We prospectively enrolled 67 patients undergoing elective off-pump CABG. HRV was assessed using 15 min high-resolution ECGs. Linear and nonlinear HRV parameters were analyzed. Postoperative AF was monitored through continuous ECG (days 0–4), daily 12-lead ECGs (days 5–7), and a 24 h Holter ECG on day 7. Statistical comparisons between AF and non-AF groups were performed, and the predictive accuracy was evaluated using ROC analysis. Results: Postoperative AF occurred in 40.3% (n = 27) of patients. Standard HRV measures (total power, frequency components, LF/HF ratio) did not differ significantly between groups. However, preoperative DFA Alpha 1 was significantly lower in patients who developed AF (p = 0.010) and showed the highest predictive value (AUC = 0.725, specificity = 80%). Alpha 1 also remained significantly reduced postoperatively in the AF group. Other nonlinear parameters, such as low and average fractal dimension, were also lower postoperatively in the AF group. Conclusions: Traditional HRV parameters showed limited predictive value for postoperative AF following off-pump CABG. The nonlinear DFA Alpha 1 index demonstrated a moderate predictive performance and may serve as a useful marker of autonomic dysregulation. Incorporating nonlinear HRV measures into preoperative assessment may improve AF risk stratification.

Background: The hallmarks of fibromyalgia (FM), a chronic pain syndrome, include tiredness, cognitive impairment, and extensive musculoskeletal discomfort. An imbalance in the autonomic nerve system may play a major role in its pathogenesis, leading to changes in visceral and cardiovascular control, according to mounting evidence. Heart rate variability (HRV) is a sensitive, non-invasive measure of sympathovagal balance and autonomic regulation. Aims and Objectives: The purpose of this study was to compare HRV indices between FM patients and age- and sex-matched healthy controls in order to evaluate autonomic dysfunction in FM utilizing short-term HRV analysis. Materials and Methods: Thirty patients with FM diagnosed using the 2016 updated American College of Rheumatology’s criteria, and 30 healthy volunteers were included in this cross-sectional research. In accordance with Task Force standards, standardized 5-min rested electrocardiograms were obtained, and HRV characteristics were examined in the time domains and frequency domains. The data were analyzed using Statistical Package for the Social Sciences 26.0, with t-tests for between-group comparisons. P&lt;0.05 was considered statistically significant. Results: When compared to healthy controls, FM patients showed a significant decrease in HRV indicators. The RMSSD was 19.3±7.2 ms compared to 38.7 ± 10.1 ms (P&lt;0.001*), and the mean standard deviation of NN intervals (SDNN) was 22.6±8.1 ms rather than 41.2±9.4 ms (P&lt;0.001*). Frequency-domain measurements revealed a higher low-frequency/high-frequency (LF/HF) ratio (1.72±0.65 vs. 1.15±0.48, P=0.003*), indicating greater sympathetic dominance and decreased parasympathetic modulation, along with significantly lower LF power (315±120 ms2 vs. 520±160 ms2, P&lt;0.001*) and HF power (210±98 ms2 vs. 450±142 ms2, P&lt;0.001*). Conclusion: Significantly decreased HRV in both the temporal and frequency domains is a symptom of substantial autonomic dysfunction linked to FM. The concept of impaired central autonomic control in FM is supported by these data, which highlight a condition of sympathovagal imbalance. For determining the severity of an illness and tracking treatment plans meant to restore autonomic balance, HRV may be a helpful biomarker.