Heart Rate Variability Monitoring Research Articles

Nocturnal Heart Rate Variability in Women Discordant for Hormonal Contraceptive Use.

The aim of this study was to investigate within-cycle differences in nocturnal heart rate (HR) and heart rate variability (HRV) in naturally menstruating women (NM) and women using combined hormonal contraceptives (CU) or progestin-only hormonal contraceptives (PU). Physically active participants were recruited into three groups: NM ( n = 19), CU ( n = 11), and PU ( n = 12). Participants' HR and HRV (with Bodyguard 2 HRV monitor) and blood hormones were monitored during one menstrual cycle (MC) (NM group) or for 4 wk (CU and PU groups). Estradiol, progesterone, and luteinizing hormone were analyzed from fasting blood samples collected four times in the NM (M1 = bleeding, M2 = follicular phase, M3 = ovulation, and M4 = luteal phase) and PU groups (M1 = lowest E 2 , M2 = M1 + 7 d, M3 = M1 + 14 d, and M4 = M1 + 21 d) and twice in the CU group (active and inactive pill phases). After every blood sample, nightly HR and HRV were recorded and examined as an average from two nights. Hormonal concentrations differed ( P < 0.05) between MC phases in the NM and PU groups, but not ( P ≥ 0.116) between the active and the inactive phases in the CU group. In the NM and PU groups, some of the HRV values were higher, whereas in the NM group, HR was lower during M2 compared with M3 ( P < 0.049) and M4 ( P < 0.035). In the CU group, HRV values ( P = 0.014-0.038) were higher, and HR was lower ( P = 0.038) in the inactive phase compared with the first week of the active phase. The MC and the hormonal cycle phases influence autonomic nervous system balance, which is reflected in measurements of nocturnal HR and HRV. This should be considered when monitoring recovery in physically active individuals.

Impact of Cancer and 12 Weeks of Chemotherapy on the Balance of the Autonomic Nervous System in Cancer Patients

Cancer and its treatment itself (especially chemotherapy) is associated with number of negative effects on the human body. These include mainly cardiac toxicity, peripheral neuropathy, bone loss, depression, anxiety, nausea, pain, cognitive changes, fatigue, fitness reduction and more. Fatigue is one of the most common negative effects, often persists long after treatment and is described as insurmountable and is associated with lower parasympathetic activity. The autonomic nervous system (ANS) is the main homeostatic regulatory system of the body, it regulates involuntary physiological processes. We believe that this part of the peripheral nervous system can be negatively affected by cancer and chemotherapy, which can have a negative impact on all the processes that control this system. Most drugs used in oncology lead to chemotherapy-induced peripheral neuropathy and are expected to have an influence on the autonomic nervous system. Activity and balance of the autonomic nervous system depend on a range of dynamically changing and quantitatively different conditions such as age, stress, physical activity, sleep, illness, fatigue and more. Methods: To evaluate ANS activity, spectral analysis of heart rate variability (HRV) was assessed. During treatment, 19 oncological patients with prescribed adjuvant chemotherapy measured HRV 3 times a week using a chest strap with a HRV monitor mySASY and mySASY software. Parasympathetic activity (PA), sympathetic activity (S), total score (TS) and total power (TP) were selected as indicators of ANS activity. The patients were women aged 50.38 ± 10,29 with BMI 25,72 ± 4,16. The mean values for the first 14 days of treatment and then for 14 days after 12 weeks of treatment were compared. Data normality was verified by Kolmogorov-Smirnov test (K-S) and static significance was calculated by t-test. All statistical tests were performed at a significance level of 5%. Results: There was a significant decrease in values for three parameters. The PA decreased from 3,80 ± 1,56 to 3,14 ± 1,67 (p = .03), TP decreased from 3,65 ± 1,87 to 2,82 ± 2,08 (p = .04), TS decreased from 3,40 ± 1,67 to 2,67 ± 1,73 (p = .01). Sympathetic activity was somewhat but not significantly higher, increased from 6,74 ± 1,22 to 6,80 ± 1,44 (p = .83). Conclusion: During the 12 weeks of treatment with adjuvant chemotherapy, there was a significant reduction in parasympathetic activity, total score, and total power. A decrease in PA is usually associated with lower regenerative abilities of the organism, a decrease in TP is associated with a decrease in the activity of the entire ANS. TS evaluates the total power and balance of both ANS branches. The higher the values, the more the body is regenerated and ready for further stress and response to stress.

Contactless Camera-Based Sleep Staging: The HealthBed Study.

Polysomnography (PSG) remains the gold standard for sleep monitoring but is obtrusive in nature. Advances in camera sensor technology and data analysis techniques enable contactless monitoring of heart rate variability (HRV). In turn, this may allow remote assessment of sleep stages, as different HRV metrics indirectly reflect the expression of sleep stages. We evaluated a camera-based remote photoplethysmography (PPG) setup to perform automated classification of sleep stages in near darkness. Based on the contactless measurement of pulse rate variability, we use a previously developed HRV-based algorithm for 3 and 4-class sleep stage classification. Performance was evaluated on data of 46 healthy participants obtained from simultaneous overnight recording of PSG and camera-based remote PPG. To validate the results and for benchmarking purposes, the same algorithm was used to classify sleep stages based on the corresponding ECG data. Compared to manually scored PSG, the remote PPG-based algorithm achieved moderate agreement on both 3 class (Wake-N1/N2/N3-REM) and 4 class (Wake-N1/N2-N3-REM) classification, with average κ of 0.58 and 0.49 and accuracy of 81% and 68%, respectively. This is in range with other performance metrics reported on sensing technologies for wearable sleep staging, showing the potential of video-based non-contact sleep staging.

Utilizing Unobtrusive Portable Electronic Devices for Real-Time Assessment of Indoor PM2.5 and tVOC Exposure and Its Correlation with Heart Rate Variability

Real-time monitoring of Heart Rate Variability (HRV) and Indoor Air Quality (IAQ) can help individuals and organizations identify potential causes of poor indoor air quality and implement corrective measures to improve the indoor environment as well as evaluating the effectiveness of interventions and measuring their impact on both HRV and overall health and well-being. Simultaneously measuring HRV and IAQ allows for the real-time observation of the correlation between the two. The proposed solution uses a non-intrusive system utilizing the wrist wearable MAXREFDES103# Health Sensor Band by Maxim Integrated® and the portable Atmotube PRO by ATMOTECH INC® for real-time monitoring of HRV and IAQ, respectively. The results of the deployment provide evidence that exposure to Particulate Matter (PM) and total Volatile Organic Compounds (tVOC), has a negative impact on HRV. The data indicates that for every increase of 10.37 μg/m3 in PM2.5 and 57.4ppb in tVOC, there was an average decrease of 5.3% in SDNN and 7.08% in RMSSD of HRV. The findings of this study have important implications for public health, as HRV is a useful indicator of cardiovascular health.

Compliance to training load and heart rate variability monitoring in young Swiss judokas

Introduction: Assessment of exercise training load (TL) can identify mechanisms of fatigue and injury. At present, techniques to monitor TL in young athletes are lacking. Objectives: To examine the adherence to two monitoring techniques to assess TL among young judokas. Methods: Over a 10 week study period, TL was assessed by completion of a daily training log and by weekly measurement of heart rate variability (HRV). The satisfaction to HRV method was assessed by survey at study completion. Results: Among national caliber judokas (n=10, age 16 ± 2 y, weight 63 ± 5 kg, height 169 ± 8 cm,), training logs were completed at a 98 ± 5% rate, while HRV measurement was successful 57% ± 37%. HRV was comparable to young and athletic population. Difficulties in performing HRV measurements were rated 3.3 ± 1.9 (1: not constraining to 10: extremely constraining). Conclusion: Excellent adhesion for training diary completion was only possible with regular demands from coaches for ratings. Judo seems to enhance cardiac autonomic control in young national level athletes. HRV monitoring compliance was suboptimal among young judokas and opportunities for future improvement are suggested by our data.

ХАРАКТЕРИСТИКА ФУНКЦИОНАЛЬНОГО СОСТОЯНИЯ СЕРДЕЧНО-СОСУДИСТОЙ СИСТЕМЫ У СПОРТСМЕНОВ С ПАТОЛОГИЕЙ СЛУХА, ПРОЖИВАЮЩИХ В УСЛОВИЯХ СЕВЕРНОГО РЕГИОНА

The study aims to assess the functionality of the cardiovascular system’s condition in athletes with hearing impairment who live in the North region. 22 higher qualification volleyball players (26.42 ± 6.75 y. o.) with hearing impairment who had lived in the North region for at least 10 years participated in the research. Based on 5-min RR intervals measured at rest, the authors examined the functionality of the cardiovascular system’s condition in athletes with hearing impairment. The statistical indicators of RR intervals and indicators of variation heart rate monitoring were evaluated. The study determined the indicators of variation heart rate monitoring and statistical indicators of heart rate variability in athletes with hearing impairment that were defined by increased parasympathetic regulatory effects combined with a moderate increase in ergotropic reactions of regulatory systems on heart rhythm modulation. Due to the centralization of heart rhythm management, intense physical activity causes a moderate tension of autonomic regulation mechanisms in some volleyball players with hearing impairment.

Neurogenic Supine Hypertension and Cardiovascular Autonomic Dysfunction in Patients with Parkinson's Disease.

Natural history and disease progression in patients with Idiopathic Parkinson's Disease (PD) is quite heterogeneous. Autonomic dysfunction occurs commonly among Idiopathic PD patients. Heart rate variability and ambulatory blood pressure monitoring are used to assess cardiac autonomic dysfunction. The prevalence and magnitude of supine hypertension in Indian PD patients has not been studied to date. The present study aimed to record cardiovascular autonomic functions and supine hypertension in PD patients and to correlate them with the age of onset, duration and severity of the disease, and non-motor symptom burden. The cross-sectional study involved 60 PD patients. Webster rating scale was used to determine the disease severity. Non-motor symptom burden was assessed using the Non-Motor Symptom Scale (NMSS). Ambulatory blood pressure monitoring and heart rate variability parameters determined cardiac autonomic function. Supine hypertension was defined as Systolic Blood Pressure (SBP) ≥150 mmHg and/or DBP ≥90 mmHg. Less than 10% decrease or even increase in blood pressure during the night were classified as non-dippers. Pearson coefficient was used appropriately to establish correlation. P ≤ 0.05 was considered significant. Age of onset was 61.2 ± 8.7 years and duration of disease was 1.7 ± 1.1 years. Mean Webster and non-motor symptom scores were 12.7 ± 4.4 and 15.5 ± 8.0, respectively. About 50 patients (83%) were non-dipper, while 32 (53%) had supine hypertension. Low Frequency oscillations (LF) (r = 0.28), High Frequency oscillations (HF) (r = 0.29), Standard Deviation NN intervals (SDNN) (0.26), and Root Mean Squared Successive Differences of NN intervals (RMSSD) (r = 0.28) correlated significantly with non-motor symptoms scale. LF (r = -0.39), HF (r = -0.43), SDNN (-0.40), RMSSD (r = -0.41), NN50 (r = -0.38), PNN50 (r = -0.42), mean SBP (r = 0.26), and mean DBP (r = 0.33) correlated significantly with disease duration. PNN50 (r = -0.255), mean SBP (r = -0.29), and mean DBP (r = -0.27) correlated significantly with age at onset. Awareness regarding neurogenic supine hypertension is needed as it occurs commonly among Indian PD patients. Heart rate variability (HRV) parameters and ambulatory blood pressure are of significant help in the detection of early cardiovascular autonomic dysfunction and correlate significantly with disease duration and non-motor symptom burden among PD patients.

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.

Prospective multicenter study of heart rate variability with ANI monitor as predictor of mortality in critically ill patients with COVID-19

The purpose of this study is to demonstrate that the most critically ill patients with COVID-19 have greater autonomic nervous system dysregulation and assessing the heart rate variability, allows us to predict severity and 30-day mortality. This was a multicentre, prospective, cohort study. Patients were divided into two groups depending on the 30-day mortality. The heart rate variability and more specifically the relative parasympathetic activity (ANIm), and the SDNN (Energy), were measured. To predict severity and mortality multivariate analyses of ANIm, Energy, SOFA score, and RASS scales were conducted. 112 patients were collected, the survival group (n = 55) and the deceased group (n = 57). The ANIm value was higher (p = 0.013) and the Energy was lower in the deceased group (p = 0.001); Higher Energy was correlated with higher survival days (p = 0.009), and a limit value of 0.31 s predicted mortalities with a sensitivity of 71.9% and a specificity of 74.5%. Autonomic nervous system and heart rate variability monitoring in critically ill patients with COVID-19 allows for predicting survival days and 30-day mortality through the Energy value. Those patients with greater severity and mortality showed higher sympathetic depletion with a predominance of relative parasympathetic activity.

Using apple watch ECG data for heart rate variability monitoring and stress prediction: A pilot study.

Stress is an increasingly prevalent mental health condition that can have serious effects on human health. The development of stress prediction tools would greatly benefit public health by allowing policy initiatives and early stress-reducing interventions. The advent of mobile health technologies including smartphones and smartwatches has made it possible to collect objective, real-time, and continuous health data. We sought to pilot the collection of heart rate variability data from the Apple Watch electrocardiograph (ECG) sensor and apply machine learning techniques to develop a stress prediction tool. Random Forest (RF) and Support Vector Machines (SVM) were used to model stress based on ECG measurements and stress questionnaire data collected from 33 study participants. Data were stratified into socio-demographic classes to further explore our prediction model. Overall, the RF model performed slightly better than SVM, with results having an accuracy within the low end of state-of-the-art. Our models showed specificity in their capacity to assess "no stress" states but were less successful at capturing "stress" states. Overall, the results presented here suggest that, with further development and refinement, Apple Watch ECG sensor data could be used to develop a stress prediction tool. A wearable device capable of continuous, real-time stress monitoring would enable individuals to respond early to changes in their mental health. Furthermore, large-scale data collection from such devices would inform public health initiatives and policies.

Continuous heart rate variability monitoring of freely moving chicken through a wearable electrocardiography recording system

Identification and quantification of stress and stress inducing factors are important components of animal welfare assessment and essential parts of poultry management. Measurement of the autonomic nervous system's influence on cardiac function using heart rate and heart rate variability (HR/HRV) indices can provide a non-invasive assessment of the welfare status of an animal. This paper presents a preliminary study showing the feasibility of continuous long-term measurement of HR/HRV indices in freely moving chicken. We developed and evaluated an electrocardiography (ECG) based HR/HRV recording system that can be used as a poultry wearable backpack for research studies. The backpack system was first validated against a commercial ECG amplifier, and the corresponding estimations of HR values matched well with each other. Then, an in vivo proof-of-concept experiment was conducted on floor-reared chickens to collect ECG data for 2 weeks. The extracted HR/HRV values show strong alignment with circadian patterns and well-defined sleep cycles. Wearable devices, like the backpack ECG system used in this study, may be best suited for application in freely moving poultry to get an insight into circadian abnormalities and sleep quality for stress and welfare management.

Monitoring Heart Rate Variability Based on Self-powered ECG Sensor Tag

This paper proposes a batteryless sensing and computational device to collect and process electrocardiography (ECG) signals for monitoring heart rate variability (HRV). The proposed system comprises of a passive UHF radio frequency identification (RFID) tag, an extreme low power microcontroller, a low-power ECG circuit, and a radio frequency (RF) energy harvester. The microcontroller and ECG circuits consume less power of only ~30 µA and ~3 mA, respectively. Therefore, the proposed RF harvester operating at frequency band of 902 - 928 MHz can sufficiently collect available energy from the RFID reader to supply power to the system within a maximum distance of ~2 m. To extract R-peak of the ECG signal, a robust algorithm that consumes less time processing is also developed. The information of R-peaks is stored into an Electronic Product Code (EPC) Class 1st Generation 1st compliant ID of the tag and read by the reader. This reader is functioned to collected the R-peak data with sampling rate of 100ms; therefore, the user application can monitor fully range of HRV. The performance of the proposed system shows that this study can provide a good solution in paving the way to new classes of healthcare applications.

Validation of a new smart textiles biotechnology for heart rate variability monitoring in sheep.

Robust Animal-Based Measures (ABMs) are fundamental in order to assess animal welfare, however in semi-extensive sheep farming systems is not easy to collect ABMs without inducing additional stress in the animals. Heart rate variability (HRV) is a non-invasive technique of assessing stress levels related to animal welfare. It is considered a sensitive indicator of the functional regulatory characteristics of the autonomic nervous system. Several studies investigated the use of HRV for welfare assessment in dairy cows while research on sheep is scarce. Moreover, assessing HRV in small ruminants at pasture is critical because of the lack of a solution adoptable for field conditions. This study aimed to evaluate if a smart textiles technology is comparable to a Standard base-apex electrocardiogram (ECG) for measuring HRV in small ruminants. Eight healthy Massese dairy sheep were recruited. Standard base-apex ECG and smart textiles technology (Smartex ECG) were simultaneously acquired for 5 min in the standing, unsedated, unclipped sheep. The ECG tracings were recorded when animals were standing quietly. The Bland-Altman test and the linear regression analysis were applied after parameter extraction in time, frequency, and non-linear methods to compare Smartex against standard base-apex ECG systems. The Bland-Altman test was applied to all HRV extracted parameters (Mean RR, pNN50, RMSSD, LF/HF, SampEn, SD1, SD2, stdRR) to evaluate the agreement between the two different instruments, and a linear regression analysis was performed to evaluate the relationship between the two methods. The smart textiles biotechnology was simple to wear and clean. It can be worn without using glue and without shaving the sheep's wool, limiting animal handling and stress. Bland Altman test reported a robust agreement between the two systems. In fact, the regression analysis of HRV parameters showed that half of the parameters recorded had an R2 coefficient >0.75. Results also showed a very small reproducibility coefficient that indicated that the two methods were really close to each other. Smartex textiles technology can be used for HRV evaluation in sheep species as a potential ABM for animal welfare assessment.

The Utilization of Heart Rate Variability for Autonomic Nervous System Assessment in Healthy Pregnant Women: Systematic Review

Background The autonomic nervous system (ANS) plays a central role in pregnancy-induced adaptations, and failure in the required adaptations is associated with adverse neonatal and maternal outcomes. Mapping maternal ANS function in healthy pregnancy may help to understand ANS function. Objective This study aimed to systematically review studies on the use of heart rate variability (HRV) monitoring to measure ANS function during pregnancy and determine whether specific HRV patterns representing normal ANS function have been identified during pregnancy. Methods The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guideline was used to guide the systematic review. The CINAHL, PubMed, SCOPUS, and Web of Science databases were searched to comprehensively identify articles without a time span limitation. Studies were included if they assessed HRV in healthy pregnant individuals at least once during pregnancy or labor, with or without a comparison group (eg, complicated pregnancy). Quality assessment of the included literature was performed using the National Heart, Lung, and Blood Institute (NHLBI) tool. A narrative synthesis approach was used for data extraction and analysis, as the articles were heterogenous in scope, approaches, methods, and variables assessed, which precluded traditional meta-analysis approaches being used. Results After full screening, 8 studies met the inclusion criteria. In 88% (7/8) of the studies, HRV was measured using electrocardiogram and operationalized in 3 different ways: linear frequency domain (FD), linear time domain (TD), and nonlinear methods. FD was measured in all (8/8), TD in 75% (6/8), and nonlinear methods in 25% (2/8) of the studies. The assessment duration varied from 5 minutes to 24 hours. TD indexes and most of the FD indexes decreased from the first to the third trimesters in the majority (5/7, 71%) of the studies. Of the FD indexes, low frequency (LF [nu]) and the LF/high frequency (HF) ratio showed an ascending trend from early to late pregnancy, indicating an increase in sympathetic activity toward the end of the pregnancy. Conclusions We identified 3 HRV operationalization methods along with potentially indicative HRV patterns. However, we found no justification for the selection of measurement tools, measurement time frames, and operationalization methods, which threaten the generalizability and reliability of pattern findings. More research is needed to determine the criteria and methods for determining HRV patterns corresponding to ANS functioning in healthy pregnant persons.

Monitoring Heart Rate Variability and Its Association with High-Intensity Running, Psychometric Status, and Training Load in Elite Female Soccer Players during Match Weeks

In order to maximize adaptations to reach high performance, sports coaches must regularly monitor the healing process following competitions or important training sessions and maintain psychometric status. As a result, the objective of this study was to track heart rate variability (HRV) in elite Spanish female soccer players during match weeks and examine its connection to high-intensity running, psychometric status, and training load. Changes in the nocturnal HRV measured along the square root of differences between adjacent RR intervals of 4 h (rMSSD 4 h) during the first phase of slow wave sleep (rMSSD 5 min), resting heart rate (RHR 4 h and RHR 5 min) were recorded with Firstbeat Bodyguard 2 (Firstbeat Technologies, Jyvaskyla, Finland). Training and match loads were recorded with rating perceived exertion and high-intensity running data by using a global positioning system (GPS) device (SPI-Pro X, GPSports). Ultimately, the psychometric test was recorded by a 5-item questionnaire, and all data were analyzed across three weeks of a competitive season. The day of the match found the lowest HRV, while the day following the match found a substantial (p &lt; 0.01) rise in rMSSD 4 h and rMSSD 5 min. Similarly, these variables showed significant differences two days after the match. Similarly, these variables showed significant differences two days after the match. Furthermore, significant differences were found between the RHR 4 h and RHR 5 min (p &lt; 0.01) and rMSSD 4 h and rMSSD 5 min (p &lt; 0.05) and variables after two days with a higher training load. The results gathered from the psychometric tests, and the various HR markers showed significant associations. As a result, HRV, RHR, and psychometric assessments are probably sensitive to changes in load within a microcycle, providing a straightforward and non-invasive technique to assess changes in the recovery/fatigue status of top-level female soccer players.

Abstract 12326: Heart Rate Variability According to Ambulatory Glucose Profile in Patients With Diabetes Mellitus

Introduction: Autonomic neuropathy commonly arises as a long-term complication in diabetes mellitus (DM) and can be diagnosed from heart rate variability (HRV), calculated from electrocardiogram (ECG) recordings. Hypothesis: There is limited data about HRV using real-time ECG and ambulatory glucose monitor in patients with diabetes mellitus Methods: Total of 43 patients (66.3±7.5 years) with DM underwent continuous real-time ECG monitor (225.7±107.3 hours) for HRV and ambulatory glucose monitor using remote monitoring system. And we compared HRV according to ambulatory glucose profile . Results: During the monitor, we checked total 15090 times of ECG and ambulatory glucose level simultaneously of all patients. Both time and frequency domain HRV were lower when the patients had poor controlled glucose level (&gt;200mg/dL) as compared with normally controlled glucose levels (&lt;200mg/dL) in Table. In addition, Heart rate and respiration rate increased according to real-time glucose level (P&lt;0.001). Conclusions: Poor controlled glucose level was independently associated with lower HRV in patients with DM. This is further substantiated by independent continuous associations between real-time measures of hyperglycemia and lower HRV. These data strongly suggest that cardiac autonomic dysfunction can be caused by elevated blood sugar alone.

Effectiveness of smart wrist wearables for distinguishing physical and cognitive demands

Wrist-worn wearables, with sensors to measure physiological responses such as heart rate variability (HRV) and electrodermal activity (EDA), have been increasing and have the potential to be used for continuous monitoring. These devices have been used to detect responses in workers’ physical and cognitive demands; however, the accuracy of wrist wearables for distinguishing these demands is unknown, especially since many every day and work activities frequently require motion. The objective of this study was to evaluate the effectiveness of a wrist-worn wearable in measuring physiological changes during different demand conditions. Participants (n = 20 college students) completed a multi-factor laboratory study that considered task (cognitive/physical), difficulty (easy/hard), and motion (motion/no motion). N-back tasks and stationary bike tasks were used to represent cognitive and physical demands, respectively. Metrics of HRV and EDA were measured using reference-standard devices and a validated wrist-wearable. Significant differences between task, motion, and difficulty were observed from HRV measurements from the reference-standard and wrist-worn devices. Wrist wearables are sensitive to detecting workplace demands and may be used as an alternative to reference-standard sensors for continuous health and activity monitoring for worker health and wellness. Findings in this study can provide guidelines on task and conditions that affect the use and interpretation of wrist-worn devices for measuring cognitive and physical demands in healthcare systems. HIGHLIGHTS Applications for noninvasive, wrist-worn sensors can be used for continuous health and exercise monitoring HRV and EDA metrics obtained from wrist-worn device are sensitivity in detecting changes in task, difficulty, and motion HRV metric from wrist-worn device had agreement with reference-standard device Wrist-wearables has potential for ubiquitous health monitoring of individuals

Risk stratification parameters as assessed by continuous long-term cardiac monitoring in pulmonary hypertension – heart rate variability, heart rate, and physical activity

Abstract Background Pulmonary hypertension (PH) is a progressive disease affecting both the pulmonary vasculature and the heart. In the current ESC/ERS guidelines nine variables are used in PH risk assessment, and have been proven to be independent predictors of survival in PH. The risk assessment parameters include clinical symptoms, exercise capacity and imaging. The present study is the first to assess continuous 24/7 heart rate variability (HRV), heart rate (HR) and physical activity monitoring in patients with PH. Purpose To identify risk stratification parameters by continuous cardiac monitoring in PH. Methods Patients diagnosed with PH were included in this prospective single-centre study. Patients had a Reveal LINQ insertable cardiac monitor implanted to continuously monitor heart rate variability (HRV), heart rate at day and night and physical activity. HRV was expressed as the mean HRV in sinus rhythm during each full day (SDANN method). Pearson and Spearman correlations between the loop recorder variables and ESC/ERS risk stratification variables were calculated and compared with the loop recorder data in 30-days intervals. Results A total of 41 patients were prospectively enrolled, 27 patients with pulmonary arterial hypertension (PAH) and 14 patients with chronic thromboembolic pulmonary hypertension (CTPEH). The patients were monitored continuously in a total of 82 patient-years, had a mean age of 58 years and were primarily in a stable disease phase with a mean WHO functional class (FC) of 2.2. HRV and physical activity divided by heart rate at daytime showed the highest correlations respectively with current risk parameters. In particular, high correlations were found between HRV and NT-proBNP (R=−0,69 p≤2.2e-16), WHO FC (R=−0,65 p=2.4e-5), RVEF (R=0,61 p=0,00012) and right atrial pressure (RAP) (R=−0.67 p=0.0023) (Figure 1). Conclusion This study demonstrates the potential of HRV, and physical activity divided by heart rate daytime as risk parameters in pulmonary hypertension. Progression of symptoms in PH are often delayed compared with pathophysiological changes, and continuous monitoring offers a potential to early recognition of disease progression and optimization of PAH therapy. Funding Acknowledgement Type of funding sources: Private company. Main funding source(s): The study was supported by the Heart Centre Research Council,Rigshospitalet and an investigator initiated study research grant fromJansson Pharmaceuticals.

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.

Contactless Monitoring of Heart Rate Variability During Respiratory Maneuvers

Heart rate variability (HRV) is a noninvasive marker for the cardiovascular system and the substantial influence of this system on the autonomous nervous system (ANS). Contact and remote photoplethysmography (PPG) proved to be a reliable means of pulse rate variability (PRV) measurement as in wearable devices or imaging PPG using video cameras with evolved technical specifications. However, PRV effectiveness remains unclear during controlled breathing rate. Specifically, respiratory rate, among other physiological factors, applies profound effects on ANS balance. In this study, we demonstrated that PRV can be a reliable marker, as HRV, during various controlled breathing rates. We evaluated the proposed PRV monitoring study against reference HRV obtained from an ECG measurement device. PRV was measured from video streams captured using a smartphone and a webcam for the upper abdominal section of healthy volunteers while in standing position and performing six different respiratory maneuvers. We evaluated frequency and nonlinear HRV indices. Agreement between all indices was tested for camera-based devices and ground truth for all performed tasks. The agreement presented a consistent mean close to 95% limit of agreement (LoA). Also, we employed spectral analysis and measured the spectral divergences, normalized root mean squared error (NRMSE), and correlation. Kullback-Leibler Divergence median and percentiles results indicate congruent spectrums, where the maximum median was 0.18. A significant spectral correlation with minimum value of 0.98, and relatively low spectrum NRMSE of 0.24 were observed. Moreover, the results led to HRV physiological related phenomena which agreed with physiologically interpretations found in the literature.