Altered Heart Rate Variability Research Articles

Autonomic dysregulation in long-term patients suffering from Post-COVID-19 Syndrome assessed by heart rate variability

Post-COVID-19 Syndrome (PCS) is a condition with multiple symptoms partly related to dysregulation of the autonomic nerve system. Assessment of heart rate variability (HRV) using 24 h Holter-ECG may serve as a surrogate to characterize cardiac autonomic activity. A prospective study including 103 PCS patients (time after infection = 252 days, age = 49.0 ± 11.3 years, 45.7% women) was performed and patients underwent detailed clinical screening, cardiopulmonary exercise testing, and 24 h Holter monitoring. Data of PCS patients was compared to 103 CAD patients and a healthy control group (n = 90). After correction for age and sex, frequency-related variables differed in PCS patients compared to controls including LF/HFpower, LF/HFnu, and LF/HF ratio (24 h; p ≤ 0.001). By contrast, these variables were largely comparable between PCS and CAD patients, while sympathetic activation was highest in PCS patients during the 24 h period. Overall, PCS patients showed disturbed diurnal adjustment of HRV, with impaired parasympathetic activity at night. Patients hospitalized during acute infection showed an even more pronounced overactivation of sympathetic activity compared to patients who underwent ambulant care. Our data demonstrate persistent HRV alterations in PCS patients with long-term symptom duration, suggesting a sustained impairment of sympathovagal balance. Moreover, sympathetic overstimulation and diminished parasympathetic response in long-term PCS patients are comparable to findings in CAD patients. Whether HRV variables have a prognostic value in PCS and/or might serve as biomarkers indicating a successful interventional approach warrants further longitudinal studies.

Altered Heart Rate Variability During Rest in Schizophrenia: A State Marker.

Autonomic nervous system (ANS) imbalance has been reported in a number of psychiatric disorders such as depression, schizophrenia, panic disorder, etc. Autonomic dysfunction in schizophrenia has been associated with the symptoms and manifestation of psychosis. Heart rate variability (HRV) as a tool has been widely used to assess ANS activity and the effect of disease on the sympathovagal balance. Therefore, in the present study, HRV derived from electrocardiogram (ECG) lead II at rest was investigated in order to understand the changes in frequency domain measures in patients with schizophrenia and their first-degree relatives compared to healthy controls. Twenty-five patients with schizophrenia, 24 first-degree relatives of patients, and 24 healthy controls (Diagnostic and Statistical Manual of Mental Disorders (DSM)-5; 18-45 years) were included in the study. HRV of the subjects was measured after five minutes of rest. ECG lead II was recorded for five minutes and HRV was analysed in the frequency domain: low frequency (LF), high frequency (HF), total power, and LF/HF ratio. HRV parameters and heart rate were statistically analysed for group comparisons using general linear model multivariate analysis. Patients had significantly higher minimum heart rate and lower HF (normalized units (nu)) compared to their first-degree relatives. A trend was observed in HF (nu) with the lowest in patients followed by healthy controls and first-degree relatives and LF/HF ratio was the highest in patients followed by healthy controls and first-degree relatives, although not statistically significant. No significant difference was found between first-degree relatives and healthy controls. The alteration of HRV in schizophrenia could be attributed to reduction in vagal tone and sympathetic dominance, which in turn could serve as state markers of schizophrenia.

Assessment of heart rate variability (HRV) in SN rotenone-induced lesion Parkinson's disease rat model

Parkinson’s disease (PD) is a progressive neurodegenerative disorder caused by loss of dopaminergic neurons in the substantia nigra (SN). While PD is clinically characterized by motor deficits, non-motor symptoms such as autonomic dysfunction that can lead to deficits in cardiovascular function are common in early PD. Autonomic dysfunction is an imbalance in sympathetic (SNS) and parasympathetic (PNS; vagal) tone, which directly impacts cardiovascular function and responsiveness, leading to alterations in heart rate variability (HRV). HRV is the fluctuation in time intervals between consecutive heartbeats, and reduced HRV has been linked to increased risk for cardiovascular morbidity and mortality in both cardiac and non-cardiac disorders, including those associated with PD. To gain further insight into the influence of PD on autonomic balance, we investigated measures of HRV quantified from a 20-min segment of basal ECG activity recorded in a rat model of PD generated by unilateral injection of the pesticide rotenone (ROT; n=8) into the SN; SN injection of vehicle (VEH) in a separate group of rats (n=7) served as a control. At 2-weeks after SN injection, ECG activity was recorded in urethane-anesthetized adult female Sprague-Dawley rats using needle electrodes inserted into each forepaw, RR interval data were obtained from the ECG records, and HRV was quantified using time-domain analysis to obtain SDRR and RMSSD, frequency-domain analysis to obtain spectral power in the low (LF) and high (HF) frequency bands and the LF/HF ratio, and non-linear Poincaré plot analysis to obtain SD1, SD2, and the SD1/SD2 ratio, with all data presented as mean±SE. Evaluation of mixed SNS/PNS tone measures showed that SDRR (2.89±1.09 vs 2.60±0.98 ms), relative LF power (49.9±18.9 vs 44.8±16.9% (nu)), and SD2 (4.25±1.60 vs 3.38±1.27 ms) were similar in ROT- and VEH-injected rats while evaluation of PNS tone measures showed that RMSSD (3.59±1.36 ms vs 2.00±0.75 ms) and SD1 (2.55±0.96 vs 1.42±0.53 ms) were slightly but not significantly higher in ROT-injected rats albeit relative HF power (50.1±18.9 vs 55.2±20.9% (nu)) was similar in both groups. Evaluation of sympatho-vagal balance measures showed that LF/HF ratio (1.05±0.40 vs 1.52±0.58) and SD1/SD2 ratio (0.56±0.21 vs 0.46±0.17) were similar in ROT- and VEH-injected rats albeit both measures appeared to favor slightly enhanced PNS tone in ROT-injected rats. Qualitative evaluation of Poincaré plot histogram data revealed that ROT-injected rats exhibited multiple modal clusters of beat-to-beat RR interval behaviors, suggesting that alterations in HRV are likely present. While our preliminary data show some slight alterations in HRV in ROT-injected rats, additional data are needed to improve statistical power of our comparisons as well as to better capture changes in sympatho-vagal balance and identify underlying mechanisms responsible for autonomic dysfunction in PD. Thomas Hartman Center for Parkinson's Disease Research at Stony Brook University This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Serotonin (5-HT)-1A receptor activation alters heart rate variability (HRV) in SN 6-OHDA-induced rat model of Parkinson's Disease

Parkinson’s disease (PD) is a multifaceted progressive neurodegenerative disease that includes a broad range of motor and non-motor symptoms (NMS). Autonomic nervous system (ANS) dysfunction is associated with a number of common NMS in PD that exert a profound impact on quality of life and increase the risk of mortality. ANS dysfunction, which likely precedes the onset of motor symptoms, includes changes in heart rate variability (HRV) that reflect pathological adjustments in the balance between sympathetic (SNS) and parasympathetic (PNS; vagal) influences on heart rate control. While the primary neuropathology of PD is related to the loss of dopamine neurons in the nigrostriatal pathway, serotonergic (5-HT) dysfunction also appears to play a role in the development of some motor and NMS and complications in PD. 5-HT is also known to play a critical role in cardiovascular (cardiac) regulation; thus, autonomic dysfunction in PD may be further complicated by 5-HT dysfunction. To begin to address this possibility, we investigated HRV quantified from 5-min segments of continuously recorded ECG activity before and after acute systemic administration of the 5-HT1A receptor agonist 8-OH-DPAT (DPAT) in urethane-anesthetized adult female rats at 2-weeks after unilateral injection of the neurotoxin 6-OHDA (n=11) or vehicle (VEH; n=7) directly into the substantia nigra (SN). HRV measures evaluated included standard deviation (SD) of R-R intervals (SDRR) and root mean square of successive differences in R-R (RMSSD) as time-domain measures; absolute (abs) and normalized (nu) low-frequency (LF: 0.2-0.75 Hz) and high-frequency (HF: 0.75-3.0 Hz) spectral power and the LF/HF ratio as frequency domain measures; and Poincaré plot SD perpendicular to (SD1) and along (SD2) the line of identity and the SD1/SD2 ratio as non-linear measures. For these analyses, SDRR, LF, and SD2 were considered indices of mixed cardiac SNS and PNS activity; RMSSD, HF, and SD1 were considered indices of PNS activity; and LF/HF and SD1/SD2 were considered indices of sympatho-vagal balance. Before DPAT (compared to VEH-injected rats), 6-OHDA-injected rats exhibited slightly but not significantly higher HR and lower SDRR, RMSSD, abs and nu LF power, abs HF power, LF/HF ratio, SD1, and SD2, but the R-R interval, nu HF power, and SD1/SD2 ratio were similar between the groups. Following DPAT administration, both 6-OHDA- and VEH-injected rats exhibited significantly reduced HR by ~15% and increased R-R intervals by 20%. In 6-OHDA-injected rats, DPAT also increased SDRR, RMSSD, abs HF power, SD1, and the SD1/SD2 ratio but significantly reduced nu HF power; similar trends were noted in VEH-injected rats. These data demonstrate that while most HRV measures are minimally altered under baseline conditions, 5-HT1A receptor activation can significantly alter autonomic balance and HRV metrics (especially measures associated with PNS activity) in the SN 6-OHDA-induced lesion rat model of PD. NIH NS101737; Thomas Hartman Center for Parkinson's Disease Research at Stony Brook University This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Heart rate variability modification as a predictive factor of sudden unexpected death in epilepsy: How far are we? A systematic review and meta-analysis.

Sudden unexpected death in epilepsy (SUDEP) is a sudden, unexpected death in people with epilepsy, with or without evidence of an epileptic seizure. The pathophysiological mechanism underlying SUDEP appears to be partly associated with an autonomic nervous system (ANS) dysfunction. Heart rate variability (HRV) analysis is a reliable, non-invasive method for detecting fluctuations in the ANS. In this systematic review we analyzed the data available in the literature on changes in HRV parameters in patients with SUDEP. We carried out a systematic search of the literature to identify the quantitative variations of HRV in epileptic patients with SUDEP. The following databases were used: Pubmed, Google Scholar, EMBASE, and CrossRef. A pooled analysis was carried out, and the results obtained were compared using mean difference (MD). The review was registered on the PROSPERO platform (CRD42021291586). Seven articles were included, with a total of 72 SUDEP cases associated with altered HRV parameters. Generally, a reduction of SDNN (standard deviation of the RR intervals) and RMSSD (root mean square differences of successive RR intervals) was reported in most SUDEP patients. According to MD, the SUDEP patients showed no differences in time and frequency domain parameters compared to controls. However, a trend toward increased low frequency and high frequency ratio (LF/HF) was observed in the SUDEP patients. HRV analysis is a valuable method for assessing cardiovascular risk and cardioautonomic impairment. Although a possible association between HRV variation and SUDEP has been reported, further studies are needed to assess the potential role of HRV modifications as a SUDEP biomarker.

Effect of acupuncture on heart rate variability in individuals with multiple sclerosis: a protocol for a double-blinded randomized controlled trial

Backgroung: the growing of patients with multiple sclerosis seeking acupuncture treatment is based on clinical reports of improvements in symptoms. Considering that autonomic impairment, including cardiovascular autonomic dysfunction, is not uncommon in patients with MS, neuromodulation with acupuncture could be an interesting tool to change heart rate variability in this population. Objective: to evaluate heart rate variability in patients with multiple sclerosis, during the application of acupuncture, in order to analyze the behavior of the autonomic nervous system before, during and after therapy and changes in condition after a longitudinal intervention. Methods: a double-blinded randomized sham-controlled crossover trial with a 1:1 allocation ratio will be conducted, with 40 individuals without a previous illness, who will constitute the control group, and 40 individuals with Multiple Sclerosis, who will constitute the experimental group, paired by age and sex. All participants will undertake active or sham acupuncture sessions. Discussion: according to the studies found, cardiovascular autonomic dysfunction is expected, with alterations in heart rate variability. Although neuromodulation with acupuncture can control pain and inflammation, there are still difficulties in affirming whether the balance between the sympathetic and parasympathetic systems can be changed by acupuncture. Trial registration: We registered this trial on ClinicalTrials.gov, ID: NCT05523466

Medetomidine/midazolam/fentanyl narcosis alters cardiac autonomic tone leading to conduction disorders and arrhythmias in mice

Arrhythmias are critical contributors to cardiovascular morbidity and mortality. Therapies are mainly symptomatic and often insufficient, emphasizing the need for basic research to unveil the mechanisms underlying arrhythmias and to enable better and ideally causal therapies. In translational approaches, mice are commonly used to study arrhythmia mechanisms in vivo. Experimental electrophysiology studies in mice are performed under anesthesia with medetomidine/midazolam/fentanyl (MMF) and isoflurane/fentanyl (IF) as commonly used regimens. Despite evidence of adverse effects of individual components on cardiac function, few data are available regarding the specific effects of these regimens on cardiac electrophysiology in mice. Here we present a study investigating the effects of MMF and IF narcosis on cardiac electrophysiology in vivo in C57BL/6N wild-type mice. Telemetry transmitters were implanted in a group of mice, which served as controls for baseline parameters without narcosis. In two other groups of mice, electrocardiogram and invasive electrophysiology studies were performed under narcosis (with either MMF or IF). Basic electrocardiogram parameters, heart rate variability parameters, sinus node and atrioventricular node function, and susceptibility to arrhythmias were assessed. Experimental data suggest a remarkable influence of MMF on cardiac electrophysiology compared with IF and awake animals. While IF only moderately reduced heart rate, MMF led to significant bradycardia, spontaneous arrhythmias, heart rate variability alterations as well as sinus and AV node dysfunction, and increased inducibility of ventricular arrhythmias. On the basis of these observed effects, we suggest avoiding MMF in mice, specifically when studying cardiac electrophysiology, but also whenever a regular heartbeat is required for reliable results, such as in heart failure or imaging research.

Effect of Lower Limb Venous Dilation on the Autonomic Cardiac Response among Healthy Young Men

Venous occlusion of the lower limbs, which simulates edema, can alter heart rate variability (HRV) by increasing feedback information from group III/IV sensory fibers. Our aim was to quantify this effect among healthy young men. The study group included 13 men (mean age, 20.4 years). Venous occlusion of the lower limbs was induced using a pressure cuff around both thighs. The effect of occlusion on autonomic cardiac response was quantified under occlusion pressures of 20, 60, and 100 mmHg. Compression was applied for 5 min. HRV was evaluated from changes in the low-frequency (LF) and high-frequency (HF) power of the electrocardiogram and the resulting LF/HF balance. Near-infrared spectroscopy of the leg was used to quantify the effects of occlusion on deoxyhemoglobin, measured as the area under the curve (HHb-AUC). The occlusion pressure of 100 mmHg induced a significant increase in the LF/HF ratio, compared to the baseline (p < 0.05). HHb-AUC was highest for the 100 mmHg occlusion pressure compared with the 20 and 60 mmHg pressures (p < 0.01). These findings indicate that venous dilation may elicit a shift towards sympathetic dominance in the autonomic balance.

Alterations in heart rate variability and pro-inflammatory cytokine TNF-alpha in individuals with panic disorder

Based on the autonomic flexibility–neurovisceral integration model, panic disorder (PD) has been associated with a generalized proinflammatory state and lower cardiac vagal tone. The heart rate variability (HRV) provides an index of cardiac autonomic function and reflects the parasympathetic innervation to the heart regulated by the vagus nerve. The aim of this study was to explore the heart rate variability, pro-inflammatory cytokines and their associations in individuals with PD. Short-term HRV with time and frequency domain indices as well as pro-inflammatory cytokines Interleukin-6 (IL-6) and Tumor Necrosis Factor alpha (TNF-alpha) were assessed in seventy individuals with PD (mean age: 35.64 ± 14.21 years) and thirty-three healthy controls (mean age: 38.33 ± 14.14 years). Individuals with PD showed significantly lower HRV in the time and frequency domain parameters during a short-term resting condition. A lower TNF-alpha concentration could be observed in individuals with PD in comparison to healthy controls, but no differences in IL-6. Furthermore, the HRV parameter absolute power in the low-frequency band 0.04–0.15 Hz (LF) predicted TNF-alpha concentrations. In conclusion, a lower cardiac vagal tone, decreased adaptive autonomic nervous system (ANS), and higher pro-inflammatory cytokine state could be observed in individuals with PD compared to healthy controls.

Use of Swedish smokeless tobacco during pregnancy: A systematic review of pregnancy and early life health risk.

Smokeless tobacco is a heterogeneous product group with diverse composition and prevalence globally. Tobacco use during pregnancy is concerning due to the risk of adverse pregnancy outcomes and effects on child health. Nicotine may mediate several of these effects. This systematic review measured health outcomes from Swedish smokeless tobacco (snus) use during pregnancy. Literature search was conducted by an information specialist in May 2022. We included human studies of snus use during pregnancy compared with no tobacco use, assessed risk of bias, conducted a meta-analysis and assessed confidence in effect-estimates using Gradingof Recommendations, Assessment, Development and Evaluations (GRADE). We included 18 cohort studies (42 to 1 006 398 participants). Snus use during pregnancy probably (moderate confidence in risk estimates) increase the risk of neonatal apnea, adjusted odds ratio 95% confidence interval [aOR (95% CI)] 1.96 (1.30 to 2.96). Snus use during pregnancy possibly (low confidence in risk estimates) increase the risk of stillbirths aOR 1.43 (1.02 to 1.99), extremely premature births aOR 1.69 (1.17 to 2.45), moderately premature birth aOR 1.26 (1.15 to 1.38), SGA aOR 1.26 (1.09 to 1.46), reduced birth weight mean difference of 72.47 g (110.58 g to 34.35 g reduction) and oral cleft malformations aOR 1.48 (1.00 to 2.21). It is uncertain (low confidence in risk estimates, CI crossing 1) whether snus use during pregnancy affects risk of preeclampsia aOR 1.11 (0.97 to 1.28), antenatal bleeding aOR 1.15 (0.92 to 1.44) and very premature birth aOR 1.26 (0.95 to 1.66). Risk of early neonatal mortality and altered heart rate variability is uncertain, very low confidence. Snus using mothers had increased prevalence of caesarean sections, low confidence. This systematic review reveals that use of smokeless tobacco (snus) during pregnancy may adversely impact the developing child.

Heart Rate Variability in Children with Moderate and Severe Traumatic Brain Injury: A Prospective Observational Study

AbstractThe aim of this study was to assess the feasibility of continuous monitoring of heart rate variability (HRV) in children with traumatic brain injury (TBI) hospitalized in a pediatric intensive care unit (PICU) and collect preliminary data on the association between HRV, neurological outcome, and complications. This is a prospective observational cohort study in a tertiary academic PICU. Children admitted to the PICU ≤24 hours after moderate or severe TBI were included in the study. Children suspected of being brain dead at PICU entry or with a pacemaker were excluded. Children underwent continuous monitoring of electrocardiographic (ECG) waveforms over 7 days post-TBI. HRV analysis was performed retrospectively, using a standardized, validated HRV analysis software (CIMVA). The occurrence of medical complications (“event”: intracranial hypertension, cerebral hypoperfusion, seizure, and cardiac arrest) was prospectively documented. Outcome of children 6 months post-TBI was assessed using the Glasgow Outcome Scale – Extended Pediatric (GOS-E Peds). Fifteen patients were included over a 20-month period. Thirteen patients had ECG recordings available and 4 had &gt;20% of missing ECG data. When ECG was available, HRV calculation was feasible (average 88%; range 70–97%). Significant decrease in overall HRV coefficient of variation and Poincaré SD2 (p &lt; 0.05) at 6 hours post–PICU admission was associated with an unfavorable outcome (defined as GOS-E Peds ≥ 3, or a deterioration of ≥2 points over baseline score). Several HRV metrics exhibited significant and nonsignificant variation in HRV during event. This study demonstrates that it is feasible to monitor HRV in the PICU provided ECG data are available; however, missing ECG data are not uncommon. These preliminary data suggest that altered HRV is associated with unfavorable neurological outcome and in-hospital medical complications. Larger prospective studies are needed to confirm these findings and to explore if HRV offers reliable and clinically useful prediction data that may help clinical decision making.

Screening of obstructive sleep apnea syndrome by the deep breathing technique.

Obstructive sleep apnea syndrome (OSAS) is associated with alterations in heart rate variability (HRV) in relation to chronic autonomic dysfunction. We tested the ability of the deep breathing technique-a simple way to evaluate HRV-to identify patients with OSAS. Consecutive patients referred for suspected OSAS (without obesity, diabetes, and heart diseases) were included. They underwent a measure of HRV at rest and of heart rate oscillations during expiration vs inspiration (DeltaHRDB) when breathing deeply at the resonant frequency of 6 cycles per minute (deep breathing technique) while sitting awake, followed by a nighttime polysomnography. We measured DeltaHRDB and performed temporal and spectral HRV analysis. Of 31 included participants (77% male), 14 had mild to moderate OSAS (apnea-hypopnea index median [IQR]: 18 [12]) and 17 had no OSAS. The conventional HRV analysis did not reveal any difference between the groups with vs without OSAS. However, the DeltaHRDB was lower in those with than without OSAS. Lower DeltaHRDB correlated with higher apnea-hypopnea index, arousal index, and desaturation degree. A DeltaHRDB below 11 beats per minute (bpm) predicted OSAS with a sensitivity of 100% and specificity of 86%. The deep breathing technique accurately identifies a reduction in cardiac changes in patients with mild to moderate OSAS. It could be used as a simple screening tool to select patients for polysomnography. Onanga M, Joanny S, Rivals I, etal. Screening of obstructive sleep apnea syndrome by the deep breathing technique. J Clin Sleep Med. 2023;19(2):293-302.

Repetitive bout of controlled soccer heading does not alter heart rate variability metrics: A preliminary investigation.

There is elevated unease regarding how repetitive head impacts, such as those associated with soccer heading, contribute to alterations in brain function. This study examined the extent heart rate variability (HRV) and cardiac baroreceptor sensitivity (BRS) metrics are altered immediately following an acute bout of soccer heading. Seven male elite soccer players (24.1 ± 1.5 years) completed 40 successful soccer headers in 20-min. The headers were performed under controlled circumstances using a soccer ball launcher located 25 meters away and using an initial ball velocity of 77.5 ± 3.7 km/h (heading condition). An accelerometer (xPatch) on the right mastoid process quantified linear/rotational head accelerations. Participants also completed sham (body contact) and control (non-contact) sessions. A three-lead ECG and finger photoplethysmography characterized short-term spontaneous HRV/cardiac BRS, before and after each condition. The SCAT3 indexed symptom scores pre-post exposures to all three conditions. During the heading condition, cumulative linear and rotational accelerations experienced were 1,574 ± 97.9 g and 313,761 ± 23,966 rad/s2, respectively. Heart rate trended toward an increase from pre- to post-heading (p = 0.063), however HRV metrics in the time-domain (ps > 0.260) and frequency-domain (ps > 0.327) as well as cardiac BRS (ps > 0.144) were not significantly changed following all three conditions. Following the heading condition, SCAT3 symptom severity increased (p = 0.030) with a trend for symptom score augmentation (p = 0.078) compared to control and sham. Whereas, symptoms as measured by the SCAT3 were induced following an acute bout of controlled soccer heading, these preliminary findings indicate they were not accompanied by alterations to autonomic function. Ultimately, this demonstrates further research is needed to understand the physiological underpinnings of alterations in brain function occurring immediately after a bout of soccer heading and how these may, over time, contribute to long-term neurological impairments.

Effects of prolonged working hours on heart rate variability in internal medicine physicians

Prior studies have utilized heart rate variability (HRV) as the assessment tools for psychological and physiological stress during 24-h shift. However, data regarding effects of prolonged working hours > 24 h on HRV are limited. We aimed to compare between pre- and post-call HRV among physicians who worked 24 plus 8 h. The study included 60 physicians in the internal medicine training. All subjects underwent Holter ECG monitoring for HRV assessment. We compared between HRV of an 8-h regular workday (8am to 4 pm) before on-call duty (pre-call HRV) and an 8-h workday after 24-h on-call duty (post-call HRV). The mean age was 26 ± 2.5 years. Mean total sleep time during on-call duty was 238.9 ± 88.3 min. In overall population, the time-domain and frequency-domain HRV parameters were not different between pre- and post-call day. However, the physicians reported their sleep time in the 1st quartile (< 180 min) had significant increase in SDNN, pNN50, high frequency (HF), and decrease in low/high frequency ratio (LF/HF). In contrast, the physicians reported their sleep time in the 4th quartile (> 307.5 min) had significant decrease in pNN50, LF, HF, and increase in heart rate. Multiple linear regression revealed total sleep time as an independent factor associated with pre- and post-call HRV alterations. More sleep during on call (> 5 h) was associated with HRV pattern suggesting both increased sympathetic activity and reduced parasympathetic activity, while less sleep (< 3 h) during on call was associated with post-call parasympathetic rebound HRV pattern.

Alterations in heart rate variability before and after percutaneous coronary intervention in patients with ischaemic heart disease

Objectives: Heart rate variability (HRV) is the beat-to-beat variation of heart rate and an important non-invasive tool to study the cardiac autonomic nervous system activity. Ischaemic heart disease (IHD) patients are often considered to have a state of sympathetic predominance. Elimination of myocardial ischaemia with percutaneous coronary intervention (PCI) could restore autonomic balance. Hence, this study aimed to evaluate HRV measures, after successful revascularisation among IHD patients. Materials and Methods: A total of 145 male IHD patients planned for coronary angiography were recruited. Fifteen minutes of electrocardiogram recording was done. Short-term HRV analyses of all the patients were acquired and time-domain indices (standard deviation of normal-to-normal intervals [SDNN], root-mean-squared differences of successive R-R intervals [rMSSD]) and frequency-domain indices (low-frequency [LF] power, high-frequency [HF] power and total power [TP]) were analysed. Before and after PCI, all measurements were made. Results: This study included 145 male IHD patients with the mean age of 54.57 ± 10.81 years. There was a significant decrease in SDNN, rMSSD, LF, HF and TP whereas increase in LF/HF ratio following revascularisation. These changes in measures of neurocardiac regulation correlated with risk factors and medication on regression analysis. Conclusion: Increase in LF/HF ratio with the decrease in SDNN, rMSSD, LF, HF and TP in patients with IHD who underwent coronary intervention infers changed cardiac autonomic balance with this surgical procedure. These measures could be potentially used as prognostic measures in the future studies.

Altered heart rate variability and pulse-wave velocity after spinal cord injury.

BACKGROUNDHeart rate variability (HRV) and pulse-wave velocity (PWV), indicators of cardiac function, are altered in patients with spinal cord injury (SCI), suggesting that autonomic cardiac function and arterial stiffness may underlie the high risk of cardiovascular complications in these patients. No study has simultaneously investigated HRV and PWV in the same patients.AIMTo evaluate cardiovascular complications in SCI patients by comparing HRV and PWV between patients with and without SCI.METHODSIn this cross-sectional pilot study, patients with (n = 60) and without SCI (n = 60) were recruited from December 7, 2019 to January 21, 2020. Each participant received a five-minute assessment of HRV and the cardiovascular system using the Medicore HRV Analyzer SA-3000P. Differences in HRV and PWV parameters between participants with and without SCI were statistically examined.RESULTSWe observed a significant difference between participants with and without SCI with respect to the standard deviation of all normal-to-normal intervals, square root of the mean sum of squared successive risk ratio interval differences, physical stress index, total power, very-low frequency, low frequency, high frequency, and arterial elasticity.CONCLUSIONPatients with SCI have weaker sympathetic and parasympathetic activity as well as lower arterial elasticity compared to those without, suggesting that SCI may increase cardiac function loading.

Alterations in Heart Rate Variability and Electroencephalogram during20‐MinuteExtremely Low Frequency Electric Field Treatment in Healthy Men during theEyes‐OpenCondition

AbstractOur previous study examined the neural effects of extremely low frequency electric field (ELF‐EF) using electroencephalogram (EEG) and heart rate variability (HRV) measurement and revealed that the theta power of EEG increases during 1‐min EF treatment (30 kV and 50 Hz). In the present study, the effects of a longer treatment duration were assessed. EF was applied between two electrodes, one above the head and the other under the feet, for 20 min to 10 healthy men sitting on a chair. Occipital EEG and HRV were measured in the eyes‐open condition. Power spectrum analysis showed that during the EF treatment, the power of alpha and theta rhythms as well as the low frequency component of HRV increased, and the heart rate decreased. These effects did not persist after the end of EF treatment. It is suggested that ELF‐EF treatment alters not only the brain activity but also the autonomic activity reflected in HRV. © 2022 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC.

Mild simulator sickness can alter heart rate variability, mental workload, and learning outcomes in a 360° virtual reality application for medical education: a post hoc analysis of a randomized controlled trial

Virtual reality (VR) applications could be beneficial for education, training, and treatment. However, VR may induce symptoms of simulator sickness (SS) such as difficulty focusing, difficulty concentrating, or dizziness that could impair autonomic nervous system function, affect mental workload, and worsen interventional outcomes. In the original randomized controlled trial, which explored the effectiveness of using a 360° VR video versus a two-dimensional VR video to learn history taking and physical examination skills, only the former group participants had SS. Therefore, 28 undergraduate medical students who participated in a 360° VR learning module were included in this post hoc study using a repeated measures design. Data of the Simulator Sickness Questionnaire (SSQ), heart rate variability (HRV) analysis, Task Load Index, and Mini-Clinical Evaluation Exercise were retrospectively reviewed and statistically analyzed. Ten (36%) participants had mild SS (total score > 0 and ≤ 20), and 18 (64%) had no SS symptom. Total SSQ score was positively related to the very low frequency (VLF) band power, physical demand subscale, and frustration subscale, and inversely related to physical examination score. Using multilevel modeling, the VLF power mediated the relationship between total SSQ score and physical examination score. Furthermore, frustration subscale moderated the mediating effects of the VLF power. Our results highlight the importance of documenting SS to evaluate a 360° VR training program. Furthermore, the combination of HRV analysis with mental workload measurement and outcome assessments provided the important clinical value in evaluating the effects of SS in VR applications in medical education.

Abstract P1097: Heart Rate Variability Analysis In Rodents Reveals Altered Cardiac Autonomic Regulation Following Myocardial Infarction

Heart rate variability (HRV) is an index of cardiovascular health and reflects the ability of the heart to modify beating rate in response to neurohumoral factors. Alterations of HRV have been reported in patients with myocardial infarction (MI), but whether experimental models of ischemic disease recapitulate features of HRV observed in human remains to be clarified. HRV was evaluated in female mice using electrocardiograms collected in the conscious, restrained state using a tunnel device. Naïve mice and animals after permanent coronary artery ligation (MI) were studied. HRV was assessed using time-domain, frequency-domain, and non-linear parameters. By echocardiography, all infarcted animals presented akinetic anterior LV free wall and, respect to naïve mice, a 1.8-fold increase in LV diameter and a 64% reduction in ejection fraction. At 3 to ~30 days after MI, RR interval duration was preserved with respect to non-infarcted mice, whereas standard deviation of RR interval duration (SDRR), was reduced by 61-70% at 3 days to ~30 days after MI. Standard deviation of instantaneous (SD1) and long-term (SD2) RR interval variability, indicative of parasympathetic and sympathetic influence, respectively, were derived from Poincaré plots of RR i and RR i+1 intervals. SD1 and SD2 were reduced after MI (64-73% and 61-70%, respectively). Moreover, by frequency-domain analysis, the contribution of high- (1.5-5 Hz), low- (0.15-1.5 Hz), and very low-frequency (0-0.15 Hz) components of RR interval oscillations were assessed. High-frequency components, which are under the influence of the sympathetic nervous system, were not affected after MI; low-frequency oscillations, attributed to baroreflex-mediated modulation of heart rate, were reduced at 3 and 7 days after MI, whereas very low-frequency components, attributed to the modulatory action of the renin-angiotensin system, thermoregulation, and, partly, parasympathetic activity, were reduced from 3-30 days after MI. Moreover, the ratio between low and high frequency components, indicative of sympathovagal balance, was reduced after MI. In conclusion, myocardial infarction in rodent results in altered heart rate variability, which appears to be secondary, in part, to altered autonomic regulation.

Simultaneous monitoring of activity and heart rate variability in depressed patients: A pilot study using a wearable monitor for 3 consecutive days.

Reduced activity and sleep-wake rhythm disturbances are essential features of depressive episodes. In addition, alterations in heart rate variability (HRV) have been implicated in depression. By using a wearable sensor that monitors 3-dimensional acceleration and HRV simultaneously, we examined the activity and HRV indices in depressive episode of mood disorders. Participants were 19 patients (13 major depressive disorder [MDD] and 6 bipolar depression; 11 females) and 18 controls (9 females) matched for age and ethnicity (all Japanese) who completed 3 consecutive days of all-day monitoring by a small and light device attached to the chest. Activity magnitude was significantly reduced while lying/resting time was increased in depressed patients, compared with controls. When males and females were examined separately, male, but not female, patients showed significant reduction in activity. HRV indices such as R-R interval and high-frequency power (a parameter for the parasympathetic system) were significantly decreased in patients than in controls. Significant differences in activity and HRV indices were seen only in males. Sympathetic load during sleep significantly correlated with damped rest-activity rhythm in depressed patients. The number of participants was small, and the majority of the participants were taking psychotropic medications. We obtained evidence for reduced activity, increased lying/resting time, and reduced HRV indices in male depressed patients. The simultaneous monitoring for activity and HRV suggested greater sympathetic load during sleep is associated with damped rest-activity rhythm (increased activity during sleep and decreased daytime activity), which might be a characteristic pathology of depression.