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Heart rate variability (HRV) is an early marker of risk for various health conditions, and its analysis serves as a valuable tool for assessing older adults. This study aimed to describe the reference values of HRV parameters in older adults through a systematic review of the literature. The review included searches in MEDLINE (via PubMed®), EMBASE, Latin American and Caribbean Health Literature, Scopus, and Web of Science (WOS). Studies presenting reference values for at least one HRV linear analysis measure in older adults were considered eligible. Out of 1618 studies identified, only 11 met the inclusion criteria. Sample sizes of older adults ranged from 21 to 6250 subjects. The HRV measures assessed (mean RR intervals, SDNN, RMSSD, PNN50, LF, HF, and LF/HF ratio) varied significantly between studies, with no standardized methods for HRV analysis. We concluded that reference values for HRV measures in older adults vary widely between studies. The scientific literature on HRV reference values in older adults is still limited, and future studies should standardize assessment methods for HRV measures in this population. [ABSTRACT FROM AUTHOR]

Background: Current guidelines recommend maintaining a resting heart rate below 100–110 beats per minute (bpm) for patients with atrial fibrillation (AF). However, there is a lack of research on various treatment approaches for patients with both atrial fibrillation and coronary heart disease (AF&CHD). We have discussed the primary therapeutic options for controlling resting heart rate in patients with AF&CHD. Methods: We conducted a post hoc analysis of the AFFIRM (Atrial Fibrillation Follow-up Investigation of Rhythm Management) trial. Our study included 3986(98.2%) participants with AF, of which 1522 had AF&CHD. The primary outcome was all-cause mortality. We utilized the chi-squared test to identify significant differences in categorical variables. Multivariate Cox regression analysis was performed to compare the risk of death by standard deviation of heart rate visit to visit variability quartile. Results: Compared to the AF group, a higher proportion of patients in the AF&CHD group had histories of smoking, hypertension, diabetes, heart failure, cardiomyopathy, valvular heart disease, peripheral vascular disease, bradycardia, hepatic or renal disease, pulmonary disease, and stroke (all P < 0.001). Additionally, patients with AF&CHD were more likely to undergo coronary artery bypass grafting (CABG) and pacemaker surgeries than those with AF alone. After adjusting for multiple clinical variables, patients with AF&CHD had a significantly higher risk of all-cause mortality compared to the AF group (RR = 1.79, 95% CI: 1.49–2.60; P < 0.01). Nonlinear multivariate curve-fitting analysis identified an optimal resting heart rate of 70 bpm for patients with AF&CHD (P < 0.001). Subgroup analysis revealed that patients with a resting heart rate below 70 bpm had lower all-cause mortality than those with a resting heart rate above 70 bpm (P < 0.001). Conclusions: For resting heart rates below 70 bpm, our results suggest an inverse causal relationship between genetically determined resting heart rate and all-cause mortality in patients with AF&CHD. Clinical trial number: Not applicable. [ABSTRACT FROM AUTHOR]

Purpose: Excessive tachycardia in resuscitated septic shock patients can impair hemodynamics and worsen patient outcome. We investigated whether heart rate (HR) control can be achieved without increased vasopressor requirements using the titratable highly selective, ultra-short-acting β1-blocker landiolol. Methods: This randomized, open-label, controlled trial was conducted at 20 sites in 7 European countries from 2018 to 2022 and investigated the efficacy and safety of landiolol in adult patients with septic shock and persistent tachycardia. Patients were randomly assigned to receive either landiolol along with standard treatment (n = 99) or standard treatment alone (n = 101). The combined primary endpoint was HR response (i.e., HR within the range of 80−94 beats per minute) and its maintenance without increasing vasopressor requirements during the first 24 h after treatment start. Key secondary endpoints were 28-day mortality and adverse events. Results: Out of 196 included septic shock patients, 98 received standard treatment combined with landiolol and 98 standard treatment alone. A significantly larger proportion of patients met the combined primary endpoint in the landiolol group than in the control group (39.8% [39/98] vs. 23.5% [23/98]), with a between-group difference of 16.5% (95% confidence interval [CI]: 3.4–28.8%; p = 0.013). There were no statistically significant differences between study groups in tested secondary outcomes and adverse events. Conclusion: The ultra-short-acting beta-blocker landiolol was effective in reducing and maintaining HR without increasing vasopressor requirements after 24 h in patients with septic shock and persistent tachycardia. There were no differences in adverse events and clinical outcomes such as 28-day mortality vs. standard of care. The results of this study, in the context of previous trials, do not support a treatment strategy of stringent HR reduction (< 95 bpm) in an unselected septic shock population with persistent tachycardia. Further investigations are needed to identify septic shock patient phenotypes that benefit clinically from HR control. [ABSTRACT FROM AUTHOR]

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Abstract Background Current guidelines recommend maintaining a resting heart rate below 100–110 beats per minute (bpm) for patients with atrial fibrillation (AF). However, there is a lack of research on various treatment approaches for patients with both atrial fibrillation and coronary heart disease (AF&CHD). We have discussed the primary therapeutic options for controlling resting heart rate in patients with AF&CHD. Methods We conducted a post hoc analysis of the AFFIRM (Atrial Fibrillation Follow-up Investigation of Rhythm Management) trial. Our study included 3986(98.2%) participants with AF, of which 1522 had AF&CHD. The primary outcome was all-cause mortality. We utilized the chi-squared test to identify significant differences in categorical variables. Multivariate Cox regression analysis was performed to compare the risk of death by standard deviation of heart rate visit to visit variability quartile. Results Compared to the AF group, a higher proportion of patients in the AF&CHD group had histories of smoking, hypertension, diabetes, heart failure, cardiomyopathy, valvular heart disease, peripheral vascular disease, bradycardia, hepatic or renal disease, pulmonary disease, and stroke (all P

Objectives: To screen hospitalized older adults for sarcopenia and ascertain whether correlations exist between heart rate variability (HRV), peripheral muscle strength, functional ability, independence, and nutritional aspects in this population. Methods: Observational study of hospitalized adults aged > 60 years who were clinically stable and able to complete the study assessments. HRV, functionality, peripheral muscle strength, independence, level of physical activity, nutritional aspects, and risk of death were assessed. The Shapiro-Wilk, Kruskal-Wallis, and Mann-Whitney tests and Spearman correlations were used for statistical analysis; significance was accepted at p < 0.05. Results: The sample comprised 40 older adults, of whom only nine (22.50%) did not meet criteria for sarcopenia. HRV in participants with sarcopenia correlated positively with level of physical activity (rs 0.92, p = 0.001) and nutritional condition (rs 0.79, p = 0.001), and negatively with mortality (rs -0.59, p = 0.04) (rs 0.79, p = 0.001). In older adults without sarcopenia, HRV correlated positively with independence (rs 0.83, p = 0.001) and muscle strength (rs 0.67, p = 0.04). Conclusion: Most hospitalized older adults meet criteria for sarcopenia. In this population, better autonomic control of the heart is associated with greater independence, muscle strength, physical activity level, and better nutritional status, while worse HRV is associated with a higher risk of mortality.

Abstract Background Patients with neurological disorders including stroke use rehabilitation to improve cognitive abilities, to regain motor function and to reduce the risk of further complications. Robotics-assisted tilt table technology has been developed to provide early mobilisation and to automate therapy involving the lower limbs. The aim of this study was to evaluate the feasibility of employing a feedback control system for heart rate (HR) during robotics-assisted tilt table exercise in patients after a stroke. Methods This feasibility study was designed as a case series with 12 patients ( $$n = 12$$ n = 12 ) with no restriction on the time post-stroke or on the degree of post-stroke impairment severity. A robotics-assisted tilt table was augmented with force sensors, a work rate estimation algorithm, and a biofeedback screen that facilitated volitional control of a target work rate. Dynamic models of HR response to changes in target work rate were estimated in system identification tests; nominal models were used to calculate the parameters of feedback controllers designed to give a specified closed-loop bandwidth; and the accuracy of HR control was assessed quantitatively in feedback control tests. Results Feedback control tests were successfully conducted in all 12 patients. Dynamic models of heart rate response to imposed work rate were estimated with a mean root-mean-square (RMS) model error of 2.16 beats per minute (bpm), while highly accurate feedback control of heart rate was achieved with a mean RMS tracking error (RMSE) of 2.00 bpm. Control accuracy, i.e. RMSE, was found to be strongly correlated with the magnitude of heart rate variability (HRV): patients with a low magnitude of HRV had low RMSE, i.e. more accurate HR control performance, and vice versa. Conclusions Feedback control of heart rate during robotics-assisted tilt table exercise was found to be feasible. Future work should investigate robustness aspects of the feedback control system. Modifications to the exercise modality, or alternative modalities, should be explored that allow higher levels of work rate and heart rate intensity to be achieved.

Background: Patients with neurological disorders including stroke use rehabilitation to improve cognitive abilities, to regain motor function and to reduce the risk of further complications. Robotics-assisted tilt table technology has been developed to provide early mobilisation and to automate therapy involving the lower limbs. The aim of this study was to evaluate the feasibility of employing a feedback control system for heart rate (HR) during robotics-assisted tilt table exercise in patients after a stroke. Methods: This feasibility study was designed as a case series with 12 patients ( n = 12 ) with no restriction on the time post-stroke or on the degree of post-stroke impairment severity. A robotics-assisted tilt table was augmented with force sensors, a work rate estimation algorithm, and a biofeedback screen that facilitated volitional control of a target work rate. Dynamic models of HR response to changes in target work rate were estimated in system identification tests; nominal models were used to calculate the parameters of feedback controllers designed to give a specified closed-loop bandwidth; and the accuracy of HR control was assessed quantitatively in feedback control tests. Results: Feedback control tests were successfully conducted in all 12 patients. Dynamic models of heart rate response to imposed work rate were estimated with a mean root-mean-square (RMS) model error of 2.16 beats per minute (bpm), while highly accurate feedback control of heart rate was achieved with a mean RMS tracking error (RMSE) of 2.00 bpm. Control accuracy, i.e. RMSE, was found to be strongly correlated with the magnitude of heart rate variability (HRV): patients with a low magnitude of HRV had low RMSE, i.e. more accurate HR control performance, and vice versa. Conclusions: Feedback control of heart rate during robotics-assisted tilt table exercise was found to be feasible. Future work should investigate robustness aspects of the feedback control system. Modifications to the exercise modality, or alternative modalities, should be explored that allow higher levels of work rate and heart rate intensity to be achieved. [ABSTRACT FROM AUTHOR]

Objective To analyze the management effect of home remote blood pressure and heart rate monitoring in patients with left heart failure combined with hypertension outside the hospital. Methods A total of 420 patients diagnosed with left heart failure combined with hypertension in the Department of Cardiovascular Medicine, Yuebei People′s Hospital from July 2020 to June 2021 were prospectively selected, and divided into the remote monitoring group (112 cases) and the routine follow-up group (278 cases) according to whether the patients agreed to home remote blood pressure/heart rate monitoring after discharge. The remote monitoring group would measure blood pressure and heart rate in the morning and evening every day and upload the data to the medical terminal, and the medical team would guide the patient′s lifestyle, medication and further treatment in time according to the measurement results. In the routine follow-up group, blood pressure and heart rate were measured and registered by themselves, and regular outpatient follow-up was performed. Control values of blood pressure, the incidence rate and time interval of unplanned readmissions, all-cause death and cardiovascular disease death were recorded in two groups at 1,3,6,12 months after discharge. Results The systolic blood pressure at 1,3,6,12 months after discharge, and heart rate at 6,12 months after discharge in the remote monitoring group were significantly lower than those in the conventional follow-up group, the number of unplanned readmissions was significantly lower than that in the conventional follow-up group, and the readmission time interval was significantly longer than that in the conventional follow-up group, with statistical significance (P＜0. 05）. There were no significant differences in all-cause mortality and cardiovascular disease mortality between two groups (P＞0. 05）. Conclusion Home remote blood pressure/heart rate monitoring is beneficial to the stable control of blood pressure and heart rate of patients with heart failure complicated with hypertension after discharge, delay the time interval of readmitted patients, and reduce the readmitted rate of patients. [ABSTRACT FROM AUTHOR]

Introduction: A self-paced (SP) heart rate (HR) control system proposed in a previous study was found to be feasible for healthy participants. The aims of this work were to investigate whether the SP HR control system is feasible to achieve accurate HR control in a participant with gait impairments, and to assess its interaction with an existing motor-driven body weight support (BWS) system. Methods: One participant with cerebral palsy was recruited in this case study. Three preliminary tests were completed to determine the appropriate mean value and amplitude of the target heart rate curve, and to identify a customised heart rate response model. Two series of formal self-paced heart rate control tests were then conducted to investigate the influence of different heart rate compensators and the presence of the BWS system. Results: The customised heart rate controller achieved improved accuracy in heart rate control and reduced oscillation in the treadmill target speed: the rootmean- square heart rate tracking error (RMSE) was 2.38 beats per minute (bpm) vs. 3.91 bpm (customised controller vs. nominal controller), and the average power of changes in the treadmill target speed was 0.4 X 10-4m²/s2 vs. 8.4 x 10-4m²/s². The BWS system resulted in improved HR tracking accuracy: RMSE on heart rate tracking was 3.02 bpm vs. 3.50 bpm (with BWS vs. without BWS). The BWS system had no influence on the automatic position control accuracy: RMSE on distance tracking was 0.0159m vs. 0.0164 m. Conclusion: After customising the heart rate compensator, the self-paced heart rate control system is feasible to achieve accurate heart rate control in an individual with gait impairments, and it can correctly interact with the BWS system. [ABSTRACT FROM AUTHOR]

Heart rate variability (HRV) analysis provides an assessment of cardiac vagal tone and consequently global cardiac health as well as systemic condition. In systemic diseases such as cancer and during treatments that affect the whole body, like chemotherapy, the vagus nerve activity is low and deregulated. Some studies focus on using HRV to predict mortality in oncology. However, in cancer patients, systemic alterations substantially increase artifacts during HRV measurement, especially atrial ectopic beats. Moreover, HRV may be altered by various factors (duration and time of measurement, breathing, drugs, and other confounding factors) that alter each metric in different ways. The Standard Deviation of all Normal to Normal intervals (SDNN) is the most commonly used metric to evaluate HRV in oncology, but it does not appear to be specific to the cardiac vagal tone. Thus, cardiac vagal activity diagnosis and vital prognosis of cancer patients can be biased. Our review presents the main HRV metrics that can be currently used in oncology studies and their links with vagus nerve and cancer. We present the influence of external factors and the required duration and time of measurement. Considering all these parameters, this review proposes seven key points for an assessment of HRV and cardiac vagal tone in patients with cancer.

This document summarizes a research letter that explores the effects of a drug called MK-2075 on heart rate and blood pressure in monkeys and humans. The study found that the drug caused a decrease in heart rate variability and baroreceptor sensitivity in monkeys, indicating an impact on sympathetic and parasympathetic tone. In human participants, the drug led to syncope in some cases. The study suggests that the drug may have negative effects on cardiovascular autonomic regulation, but more research is needed to fully understand its potential risks and benefits. [Extracted from the article]

A systematic review was undertaken to investigate the involvement of hydration in heart rate (HR), HR variability (HRV) and diastolic (DBP) and systolic (SBP) blood pressure in response to exercise. Data synthesis: The EMBASE, MEDLINE, Cochrane Library, CINAHL, LILACS and Web of Science databases were searched. In total, 977 studies were recognized, but only 36 were included after final screening (33 studies in meta-analysis). This study includes randomized controlled trials (RCTs) and non-RCTs with subjects > 18 years old. The hydration group consumed water or isotonic drinks, while the control group did not ingest liquids. For the hydration protocol (before, during and after exercise), the HR values during the exercise were lower compared to the controls (−6.20 bpm, 95%CI: −8.69; −3.71). In the subgroup analysis, "water ingested before and during exercise" showed lower increases in HR during exercise (−6.20, 95%CI: 11.70 to −0.71), as did "water was ingested only during exercise" (−6.12, 95%CI: −9.35 to −2.89). Water intake during exercise only revealed a trend of avoiding greater increases in HR during exercise (−4,60, 95%CI: −9.41 to 0.22), although these values were not significantly different (p = 0.06) from those of the control. "Isotonic intake during exercise" showed lower HRs than the control (−7.23 bpm, 95% CI: −11.68 to −2.79). The HRV values following the exercise were higher in the hydration protocol (SMD = 0.48, 95%CI: 0.30 to 0.67). The values of the SBP were higher than those of the controls (2.25 mmHg, 95%CI: 0.08 to 4.42). Conclusions: Hydration-attenuated exercise-induced increases in HR during exercise, improved autonomic recovery via the acceleration of cardiac vagal modulation in response to exercise and caused a modest increase in SBP values, but did not exert effects on DBP following exercise. [ABSTRACT FROM AUTHOR]

Objective: The current study examined variations in cardioautonomic lability during the Royal Canadian Mounted Police (RCMP) Cadet Training Program (CTP) between cadets starting their training who did or did not screen positive for one or more mental health disorders (i.e., posttraumatic stress disorder [PTSD], major depressive disorder [MDD], social anxiety disorder [SAD], generalized anxiety disorder [GAD], panic disorder [PD], alcohol use disorder [AUD]). Methods: Electrocardiogram (ECG) signals integrated into Hexoskin garments were used to record ECG and heart rate Over the 26-week CTP. There were 31 heart rate variability (HRV) parameters calculated using Kubios Premium HRV analysis software. Mann--Whitney U-tests were used to perform groupwise comparisons of participant raw values and HRV during the CTP. Results: A total of 157 cadets (79% male) were screened for any mental disorder using self-report surveys and then grouped by positive and negative screening. Analyses indicated a statistically significant (p < 0.05) decrease in low frequency (LF): High Frequency (HF) variability during CTP, but only for cadets who endorsed clinically significant anxiety symptoms on the GAD-7 at the start of their training. There were no other statistically significant groupwise differences. Conclusion: The results indicate the participants have excellent cardiac health overall and suggest potentially important differences between groups, such that cadets who endorsed clinically significant anxiety symptoms on the GAD-7 showed less variability in the LF:HF ratio over the course of the CTP. The relatively lower variability suggests decreased parasympathetic tone in those without clinically significant anxiety symptoms. The results also have important implications for future investigations of cardioautonomic dysfunction and chronic hypothalamic pituitary adrenal (HPA) axis deviations in policing populations with anxiety disorders; specifically, cardioautonomic inflexibility related to cardiovascular morbidity and mortality. In any case, the current results provide an important baseline for future cardiac research with cadets and serving officers. [ABSTRACT FROM AUTHOR]

Individuals diagnosed with systemic arterial hypertension (SAH) are considered risk groups for COVID-19 severity. This study assessed differences in cardiac autonomic function (CAF) and functional capacity (FC) in SAH individuals without COVID-19 infection compared to SAH individuals post-COVID-19. Participants comprised 40 SAH individuals aged 31 to 80 years old, grouped as SAH with COVID-19 (G1; n = 21) and SAH without COVID-19 (G2; n = 19). CAF was assessed via heart rate variability (HRV), measuring R–R intervals during a 10-min supine period. Four HRV indices were analyzed through symbolic analysis: 0V%, 1V%, 2LV%, and 2UV%. FC assessment was performed by a 6-min walk test (6MWT). G1 and G2 showed no significant differences in terms of age, anthropometric parameters, clinical presentation, and medication use. G2 exhibited superior 6MWT performance, covering more distance (522 ± 78 vs. 465 ± 59 m, p < 0.05). Specifically, G2 demonstrated a moderate positive correlation between 6MWT and the 2LV% index (r = 0.58; p < 0.05). Shorter walking distances were observed during 6MWT in SAH individuals post-COVID-19. However, the study did not find impaired cardiac autonomic function in SAH individuals post-COVID-19 compared to those without. This suggests that while COVID-19 impacted FC, CAF remained relatively stable in this population. [ABSTRACT FROM AUTHOR]

Atrial fibrillation is the most common arrhythmia, in emergency rooms and around the globe. Its frequency is constantly increasing and the likelihood of a physician encountering it at any time is high. Usual treatment approaches are “conservative”, traditionally including heart rate control, anticoagulation and hospitalization. The main goal with this approach is stroke prevention. As time goes by, atrial remodeling takes place and the chance to restore sinus rhythm decreases. A longer time in atrial fibrillation leads to more structural heart disease. Thus, adequate management in the emergency room for an initial or complicated episode reduces the risk of inadequate therapies and healthcare costs. This review will focus on atrial fibrillation in the emergency room according to current evidence. [ABSTRACT FROM AUTHOR]

Abstract Aims Sinus tachycardia potentially leads to a deterioration of cardiac function in critically ill infants. The ultrashort‐acting beta‐blocker landiolol hydrochloride is a new pharmacological option for a selective heart rate (HR) control in patients with sinus tachycardia and heart failure. Methods and results This study was a monocentric retrospective medical chart review study at the University Children's Hospital Bonn (Germany) from 01 January 2018 until 30 June 2020. This study included a cohort of 62 term and preterm infants with a diagnosis of ventricular dysfunction and/or pulmonary hypertension (PH), in combination with preexisting tachycardia and treatment with landiolol hydrochloride. Infants were allocated to subgroups according to weeks of gestational age (GA): born at 35 weeks of GA (Group B). Tachycardia was defined depending on GA (170 b.p.m.; ≥ 35 weeks of GA: >150 b.p.m.). The primary endpoint was defined as percentage of patients achieving HR normalization during the first 24 h of landiolol treatment. Twenty‐nine infants were allocated to Group A and 33 infants to Group B. The overall median GA of the infants was 35.3 (23.3/41.3), with 53% female infants. The primary endpoint was achieved in 57 patients (91.9%). The median time to reach target HR was 1.8 (0.3–24) h. The median starting dose of landiolol was 8.8 (3.9–25.3) μk/kg/min, with a median dosing during the first 24 h of landiolol treatment of 9.9 (2.8–35.4) μk/kg/min. The median landiolol dose while achieving the target HR was 10 (2.4–44.4) μk/kg/min. The right ventricular dysfunction improved significantly in both groups 24 h after onset of landiolol infusion (P = 0.001 in Group A and P = 0.045 in Group B). The left ventricular and biventricular dysfunction improved significantly 24 h after onset of landiolol infusion in infants of Group B (P = 0.004 and P = 0.006, respectively). The severity of PH improved significantly after 24 h in infants of Group A (P

ObjectiveThe current study examined variations in cardioautonomic lability during the Royal Canadian Mounted Police (RCMP) Cadet Training Program (CTP) between cadets starting their training who did or did not screen positive for one or more mental health disorders (i.e., posttraumatic stress disorder [PTSD], major depressive disorder [MDD], social anxiety disorder [SAD], generalized anxiety disorder [GAD], panic disorder [PD], alcohol use disorder [AUD]).MethodsElectrocardiogram (ECG) signals integrated into Hexoskin garments were used to record ECG and heart rate Over the 26-week CTP. There were 31 heart rate variability (HRV) parameters calculated using Kubios Premium HRV analysis software. Mann–Whitney U-tests were used to perform groupwise comparisons of participant raw values and HRV during the CTP.ResultsA total of 157 cadets (79% male) were screened for any mental disorder using self-report surveys and then grouped by positive and negative screening. Analyses indicated a statistically significant (p

Introduction: With conventional heart rate (HR) control systems, the exercising person is bound to walk or run at a pace determined by the feedback. This may be challenging for people with impairments that make it difficult for them to achieve a smooth, continuous pace. The aim of this work was to assess the technical feasibility of a novel self-paced heart rate control strategy and to compare its accuracy with conventional heart rate control. Methods: We propose a self-paced heart rate control system that embeds an automatic positioning controller within the heart rate control loop. The treadmill speed command is decoupled from the heart rate compensator, whereas speed is determined by the exerciser's own volition: target speed is displayed visually to the person and, when they try to follow this target, the position controller sets the treadmill speed while keeping the person at a safe reference position on the track. A further novel contribution of this work is a new input-sensitivity-shaping, frequency-domain design strategy for feedback control of position. Results: Experimental evaluation with four participants showed that self-paced heart rate control is technically feasible: all participants were able to accurately follow the target running speed calculated by the HR compensator and presented to them visually; for all four participants, self-paced HR tracking accuracy was not substantially different from conventional HR control performance; on average, the self-paced heart rate controller gave slightly better performance than conventional HR control, with RMS tracking error of 2.98 beats per minute (bpm) vs 3.11 bpm and higher average control signal power. Conclusion: The proposed self-paced heart rate control strategy with embedded automatic position control is deemed feasible. This approach may be helpful for people with gait impairments or other limitations that make it difficult for them to follow an imposed treadmill speed. [ABSTRACT FROM AUTHOR]

Aims: Sinus tachycardia potentially leads to a deterioration of cardiac function in critically ill infants. The ultrashort‐acting beta‐blocker landiolol hydrochloride is a new pharmacological option for a selective heart rate (HR) control in patients with sinus tachycardia and heart failure. Methods and results: This study was a monocentric retrospective medical chart review study at the University Children's Hospital Bonn (Germany) from 01 January 2018 until 30 June 2020. This study included a cohort of 62 term and preterm infants with a diagnosis of ventricular dysfunction and/or pulmonary hypertension (PH), in combination with preexisting tachycardia and treatment with landiolol hydrochloride. Infants were allocated to subgroups according to weeks of gestational age (GA): born at <35 weeks of GA (Group A) and born at >35 weeks of GA (Group B). Tachycardia was defined depending on GA (<35 weeks of GA: >170 b.p.m.; ≥ 35 weeks of GA: >150 b.p.m.). The primary endpoint was defined as percentage of patients achieving HR normalization during the first 24 h of landiolol treatment. Twenty‐nine infants were allocated to Group A and 33 infants to Group B. The overall median GA of the infants was 35.3 (23.3/41.3), with 53% female infants. The primary endpoint was achieved in 57 patients (91.9%). The median time to reach target HR was 1.8 (0.3–24) h. The median starting dose of landiolol was 8.8 (3.9–25.3) μk/kg/min, with a median dosing during the first 24 h of landiolol treatment of 9.9 (2.8–35.4) μk/kg/min. The median landiolol dose while achieving the target HR was 10 (2.4–44.4) μk/kg/min. The right ventricular dysfunction improved significantly in both groups 24 h after onset of landiolol infusion (P = 0.001 in Group A and P = 0.045 in Group B). The left ventricular and biventricular dysfunction improved significantly 24 h after onset of landiolol infusion in infants of Group B (P = 0.004 and P = 0.006, respectively). The severity of PH improved significantly after 24 h in infants of Group A (P < 0.001). During landiolol treatment, no severe drug‐related adverse event was noted. Conclusions: The use of landiolol hydrochloride for HR control of non‐arrhythmic tachycardia in critically ill infants is well tolerated. Reduction of HR can be guided quickly and landiolol treatment is associated with an improvement of ventricular dysfunction and PH. [ABSTRACT FROM AUTHOR]

The objective of this work is to design an Integral Sliding Mode Controller based on barrier function (ISMCbf) for a human Heart Rate (HR) during a treadmill exercise. ISMCbf commands the speed of the treadmill such that the individual HR follows a time-varying profile. This profile is pre specified as part of rehabilitation exercises for patients with cardiovascular diseases. ISMCbf is chosen due to its well-known robustness properties as well as to its simple design procedure as compared to classic SMC and ISMC. It does not require the upper bounds of the uncertainties and perturbations in its design. Moreover, it does not have discontinuous function, hence it is a chattering-free controller. ISMCbf designed in this work for the first time for this system and its performance is compared to Quasi SMC (QSMC) and Super Twisting SMC (STSMC) from previous studies. The simulated exercises were conducted on a nonlinear model describing HR response to the walking speed of a treadmill. For ISMCbf, the model parameters and their upper bound of uncertainties are considered unknown. During two different exercise scenarios, the three controllers guided HR to follow the time-varying reference profile. However, ISMCbf showed higher quantitative performance by recording less Integral Squared Error (ISE) and Integral Time Absolute Error (ITAE) indices as compared to the other controllers. [ABSTRACT FROM AUTHOR]

Background: Bus driving is a mentally demanding activity that requires prolonged attention to ensure safety. The aim of the study was to assess mental fatigue caused by driving a public bus and to find a profile of workers at higher risk. Methods: We evaluated changes of critical flicker fusion (CFF) (index of central arousal) and heart rate variability (HRV) (index of autonomic balance) in a 6-hour driving shift on a real route, in 31 professional bus drivers, and we tested the influence of personal factors such as sleep quality, BMI, and age. Paired t-test was used to test differences of CFF and HRV between both initial and final phase of driving, while multiple linear regression tested the influence of personal variables on the indexes of mental fatigue. Results: Results showed that CFF significantly decreased after 6 hours of bus driving (41.91 Hz, sd 3.31 vs. 41.15 Hz, sd 3.15; p = 0.041), and heart rate significantly decreased in the final phase of driving, with respect to the initial phase (85 vs. 78 bpm, p = 0.027). Increasing age (beta = -0.729, p = 0.022), risk of obstructive sleep apnea syndrome (beta = -0.530, p = 0.04), and diurnal sleepiness (beta = -0.406, p = 0.017) showed a significant effect on influencing mental fatigue. Conclusion: Elderly drivers at higher risk of sleep disorders are more prone to mental fatigue, when exposed to driving activity. Monitoring indexes of central arousal and autonomic balance, coupled with the use of structured questionnaires can represent a useful strategy to detect profile of workers at higher risk of mental fatigue in such duty.

[Display omitted] • DTW and k-means clustering reveal fitness levels via heart rate dynamics in real-time. • Four distinct exercise response patterns identified for personalized fitness assessment. • Higher baseline fitness shows distinct heart rate dynamics in trained participants. The appropriate measurement of cardiovascular 'Performance Enhancement' is critical for improving physical fitness and overall health. Traditional methods, effective as they are, often rely on complex, cumbersome equipment, limiting their practical use for real-time, dynamic exercise evaluation. Thus, understanding the intricate relationship between physiological responses and exercise 'Performance Enhancement' using wearable technology is essential for tailoring effective fitness regimes. This study involved 52 participants, utilizing Garmin Vivosmart 5 wearables to analyze heart rate time series during the YMCA Three-Minute Step Test, assessing fitness levels and characterizing personalized heartbeat dynamics. The study employed Dynamic Time Warping (DTW) for clustering these time series into high and low VO 2 max groups. Additionally, heart rate dynamics were examined using K-means clustering to identify distinct patterns during exercise—namely 'Efficient Adaptation', 'Balance Under Pressure', 'Active Strain', and 'Efficiency Improvement' clusters. This analysis demonstrated that non-trained individuals showed higher 'Active Strain' and 'Efficiency Improvement' dynamics and lower 'Efficient Adaptation' dynamics, indicating the exercise's varied effectiveness based on training level. This method provides a novel approach for identifying individual fitness levels and the efficacy of specific exercises, enabling personalized physical activity planning. [ABSTRACT FROM AUTHOR]

With the development and application of the Internet of Things, cloud computing, Artificial Intelligence, big data, and other information technologies, sports fitness has ushered in new development opportunities. Intelligent sports detection has emerged as the times require. This paper takes intelligent physical fitness as the research object, explores the application of digital and intelligent image processing in physical fitness, and provides a theoretical reference for popularizing and implementing intelligent physical fitness in life. Firstly, the treadmill is an example to study the current situation of fitness equipment, especially the intelligent digital treadmill, and the future development trend of fitness equipment. Secondly, the upper and lower computer control scheme is proposed. The upper computer control scheme is selected, and the industrial computer is analyzed. The motion model of the main control motor and the calculation model of the heart rate control scheme and calorie consumption are established. Finally, the software and algorithm design of the control system are summarized, and necessary debugging, experiment, and analysis are carried out. The results show that: (1) the treadmill industrial control system can correctly receive the data sent by the Automatic Voltage Regulator (AVR) and express it in the form of images, which completely matches the asynchronous communication data format. (2) The ultrasonic distance detection experiment proves that the distance precision between the operating platform and the human body is extremely high, and its digital intelligent treadmill can meet human perception and corresponding control requirements well. (3) The heart rate pulse of the human body can be collected based on digital technology. The waveform displayed in the image is relatively stable and complete.

Current data shows that the autonomic and vascular systems can influence each other. However, only a few studies have addressed this association in the general population. We aimed to investigate whether heart rate variability (HRV) was associated with coronary artery calcium (CAC) in a cross-sectional analysis of the Brazilian Longitudinal Study of Adult Health (ELSA-Brasil). We examined baseline data from 3138 participants (aged 35 to 74 years) without previous cardiovascular disease who underwent CAC score assessment and had validated HRV recordings. Prevalent CAC was defined as a CAC score>0, and HRV analyses were performed over 5-min segments. We detected CAC score>0 in 765 (24.4%) participants. Subgroup analyses in older participants (≥49 years) adjusted for sociodemographic and clinical variables revealed that CAC score>0 was associated with lower values of standard deviation of NN intervals (SDNN) (odds ratio [OR]=1.32; 95%CI: 1.05,1.65), root mean square of successive differences between adjacent NN intervals (RMSSD) (OR=1.28; 95%CI: 1.02,1.61), and low frequency (LF) (OR=1.53, 95%CI: 1.21,1.92). Interaction analysis between HRV indices and sex in age-stratified groups revealed significant effect modification: women showed increased OR for prevalent CAC in the younger group, while for men, the associations were in the older group. In conclusion, participants aged ≥49 years with low SDNN, RMSSD, and LF values were more likely to present prevalent CAC, suggesting a complex interaction between these markers in the pathogenesis of atherosclerosis. Furthermore, our results suggested that the relationship between CAC and HRV might be sex- and age-related.

Beetroot juice (BJ) has been used as a sport supplement, improving performance in resistance training (RT). However, its effect on the modulation of the autonomic nervous system has not yet been widely studied. Therefore, the objective of this randomized double-blind crossover study was to assess the effect of acute BJ supplementation compared to placebo in blood pressure (BP), heart rate (HR), heart rate variability (HRV) and internal load during RT measure as Root Mean Square of the Successive Differences between adjacent RR intervals Slope (RMSSD and RMSSD-Slope, respectively). Eleven men performed an incremental RT test (three sets at 60%, 70% and 80% of their repetition maximum) composed by back squat and bench press with. HR, HRV and RMSSD-Slope were measured during and post exercise. As the main results, RMSSD during exercise decrease in the BJ group compared to placebo (p = 0.023; ES = 0.999), there were no differences in RMSSD post-exercise, and there were differences in RMSSD-Slope between groups in favor of the BJ group (p = 0.025; ES = 1.104) with a lower internal load. In conclusion, BJ supplementation seems to be a valuable tool for the reduction in the internal load of exercise during RT measured as RMSSD-Slope while enhancing performance. [ABSTRACT FROM AUTHOR]

Background: Multiple organ dysfunction syndrome (MODS) is one of the main causes of death in intensive care units. There is evidence that microcirculation in sepsis and coronary shock is regulated separately from hemodynamics. This study investigates the relationship between heart rate (HR), cardiac output (CO) and microcirculation in patients with MODS., Methods: This is a partial analysis of the "MODIFY study" (Reducing Elevated Heart Rate in Patients With Multiple Organ Dysfunction Syndrome [MODS] by Ivabradine). During the period 05/2010-09/2011, the microcirculation of 46 patients with septic and coronary MODS was measured using the sidestream dark field technique on the day of inclusion and 96 h later. Patients were randomized into a control and ivabradine treatment group., Results: Overall, there is a relevant improvement in microcirculation over time small perfused vessels, SPV [%] on day 0, d0:56.5 ± 34.2/d4:73.2 ± 22.1 (p = 0.03); perfused vessel density, PVDsmall [1/mm 2 ] d0:7.5 ± 5.0/d4:9.8 ± 3.4 (p = 0.04); proportion of perfused vessels, PPVsmall [%] d0:51.6 ± 31.6/d4:66.7 ± 21.8 (p = 0.04); microcirculatory flow index, MFI d0:1.7 ± 1.0/d4:2.2 ± 0.7 (p = 0.05). Administration of ivabradine shows no effect. In patients with coronary MODS, there is a relevant correlation between microcirculatory parameters and cardiac output (SPV [%]: r = 0.98, p = 0.004). Patients with coronary MODS show better microcirculation values at high heart rates (> 100 bpm), while patients with septic MODS show an opposite relationship., Conclusion: The results indicate that in critically ill patients, depending on the genesis of the MODS, there are different relationships between HF or CO values, on the one hand, and the parameters of the microcirculation, on the other., (© 2023. The Author(s), under exclusive licence to Springer Medizin Verlag GmbH, ein Teil von Springer Nature.)

Guideline-directed medical therapy (GDMT) is crucial in reducing mortality in patients with heart failure with heart rate lowering by a beta blocker (BB) being an important therapeutic concept. We aimed to assess the usefulness of a wearable cardioverter/defibrillator (WCD) to provide detailed information about heart rate for managing patients with reduced left ventricular ejection fraction (LVEF) and symptoms of heart failure and to correlate mortality with the mean heart rate. A total of 4509 consecutive patients (mean age: 59 + 13 years, 88% male) were analyzed retrospectively. All patients had reduced LVEF and were prescribed a WCD for protection from sudden cardiac death (SCD) during GDMT uptitration awaiting LVEF recovery. The device continuously measured nighttime and daytime HR at the beginning and end of WCD use. Patients who died during wear time had significantly higher HRs compared with survivors: daytime beginning of use (BOU), 80 ± 15 bpm vs. 76 ± 13, p < 0.01; nighttime BOU, 76 ± 14 vs. 69 ± 13, p < 0.0001; daytime end of use (EOU), 84 ± 20 vs. 73 ± 13, p < 0.0001; nighttime EOU, 80 ± 20 vs. 65 ± 12, p < 0.0001). In conclusion, HR monitoring with a WCD yields important prognostic information and may assist in optimal usage of BB in patients with low LVEF. [ABSTRACT FROM AUTHOR]

Although neural modulation of heart rate is well established among chordate animals, the Pacific hagfish (Eptatretus stoutii) lacks any cardiac innervation, yet it can increase its heart rate from the steady, depressed heart rate seen in prolonged anoxia to almost double its normal normoxic heart rate, an almost fourfold overall change during the 1-h recovery from anoxia. The present study sought mechanistic explanations for these regulatory changes in heart rate. We provide evidence for a bicarbonate-activated, soluble adenylyl cyclase (sAC)-dependent mechanism to control heart rate, a mechanism never previously implicated in chordate cardiac control.

Background: Ivabradine is approved for heart rate reduction in patients with stable symptomatic heart failure (HF). The United States Food and Drug Administration and Taiwan Central Health Insurance Agency approved the use of ivabradine for patients with chronic stable HF with sinus rhythm, but it has not yet been approved for patients with acute decompensated HF or with atrial fibrillation (AF)., Objectives: To investigate whether short-term ivabradine use is feasible in critically ill patients with AF and rapid ventricular response (RVR)., Methods: This study retrospectively analyzed 23 patients admitted to an intensive care unit with acute HF and AF-RVR who received ivabradine. All patients initially received a slow IV of amiodarone. Other medications for HF were prescribed according to current HF guidelines. The time taken for ivabradine to reduce HR to 80 beats per minute, referred to as "Time to 80," was measured in each patient., Results: Overall, 69.6 % (16/23) of the patients had New York Heart Association functional class IV HF. In addition, 60.9% (14/23) of the patients required endotracheal intubation and ventilatory support, with more than half receiving vasopressor treatment to manage hypotension. Five patients died during the study period. The surviving patients had a significantly shorter "Time to 80" compared to those who did not survive (p = 0.037)., Conclusions: Adding ivabradine to standard treatment might be feasible for critically ill patients with AF and tachycardia. The finding that surviving patients had a shorter "Time to 80" duration than those who did not survive may have clinical implications. However, further investigations are needed to assess its clinical utility., Competing Interests: The authors declare that they have no conflicts of interest.

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Abstract Background It is essential to accomplish the appropriate emergency care particularly in patients undergoing stressful dento-oral surgical procedures. Atrial flutter may be induced by sympathetic hypertonia due to excessive mental and physical stress. There is no report regarding dental care in patients with atrial flutter. Herein, we describe a rare case of the antiarrhythmic management in an outpatient who presented with an electrocardiographic finding of paroxysmal atrial flutter before the initiation of the dento-oral surgical procedure. Case presentation A 60-year-old male patient was scheduled for a dental extraction. He had a history of angina pectoris, diabetes mellitus, and paroxysmal atrial fibrillation with medication. The preoperative electrocardiogram (ECG) revealed left ventricular hypertrophy and ST-T segment abnormality. Immediately before the dental extraction, II-lead ECG revealed atrial flutter; however, he complained of few subjective symptoms, such as precordial discomfort or palpitation. Observing the vital signs, ECG findings, and the general condition of the patient, low dose diltiazem was immediately administered by continuous infusion in order to control the heart rate and prevent atrial flutter-induced supraventricular tachyarrhythmia. Special attention was paid to prevent any critical cardiovascular condition under a preparation of intravenous disopyramide and verapamil and a defibrillator. The intravenous administration of diltiazem progressively restored the sinus rhythm after converting atrial flutter into atrial fibrillation, resulting in the prevention of tachycardia, and then was found to be appropriate as a prophylactic therapy of tachyarrhythmia. Conclusions The present case suggests that it is possible to successfully manage some of such patients using our method during dento-oral surgery which is likely to be associated with mental and physical stress. Therefore, it is essential to accomplish an initial emergency care in parallel to the differential diagnosis of unforeseen serious medical conditions or paroxysmal arrhythmia such as atrial flutter.

Abstract Background The optimal level of heart rate (HR) control in patients with atrial fibrillation (AF) is unknown. To assess the effect of rate control on cardiopulmonary exercise capacity and quality of life (QoL) in permanent AF. Methods One hundred forty-three patients with permanent AF were enrolled in this study. All patients received rate control medications and were followed up for 1 year. After 1-year therapy, the exercise capacity and QoL were evaluated by cardiopulmonary exercise testing (CPET) and 36-item Short-Form Health Survey, respectively. Data were compared by dividing the patients according to the following criteria: (1) whether the resting HR was ≤80 or > 80 bpm; (2) whether the exercise HR during moderate exercises on CPET was ≤110 or > 110 bpm; and (3) whether the resting HR was ≤80 bpm and exercise HR was ≤110 bpm. Results No significant differences in peak oxygen uptake, peak metabolic equivalent, and anaerobic threshold were found between the strict control and lenient control groups. Both physical component summary (PCS) and mental component summary (MCS) were significantly higher for the strict rate control group than for the lenient control group. The single-factor correlation analysis revealed a negative correlation between resting HR and both PCS and MCS. The multivariable linear regression analysis indicated that both exercise HR and duration of AF linearly correlated with PCS and MCS. Conclusions Therefore, in patients with permanent AF, exercise capacity may not be affected by the stringency of rate control, and strict rate control may be associated with better QoL.

It has been shown that water intake (WI) improves postexercise parasympathetic recovery after moderate-intensity exercise session. However, the potential cardiovascular benefit promoted by WI has not been investigated after high-intensity exercise. Purpose: To assess the effects of WI on post high-intensity parasympathetic recovery. Methods: Twelve recreationally active young men participated in the study (22 ± 1.4 years, 24.1 ± 1.6 kg.m–2). The experimental protocol consisted of two visits to the laboratory. Each visit consisted in the completion of a 30-min high-intensity [~80% of maximal heart rate (HR)] cycle ergometer aerobic session performing randomly the WI or control (CON, no water consumption) intervention at the end of the exercise. HR and RR intervals (RRi) were continuously recorded by a heart rate monitor before, during and after the exercise. Differences in HR recovery [e.g., absolute heart rate decrement after 1 min of recovery (HRR60s) and time-constant of the first order exponential fitting curve of the HRR (HRRτ)] and in postexercise vagal-related heart rate variability (HRV) indexes (rMSSD30s, rMSSD, pNN50, SD1 and HF) were calculated and compared for WI and CON. Results: A similar HR recovery and an increased postexercise HRV [SD1 = 9.4 ± 5.9 vs. 6.0 ± 3.9 millisecond, HF(ln) = 3.6 ± 1.4 vs. 2.4 ± 1.3 millisecond2, for WI and CON, respectively; p < .05] was observed in WI compared with CON. Conclusion: The results suggest that WI accelerates the postexercise parasympathetic reactivation after high-intensity exercise. Such outcome reveals an important cardioprotective effect of WI. [ABSTRACT FROM AUTHOR]

Background: Despite known clinical benefits, guideline-recommended heart rate (HR) control is not achieved for a significant proportion of patients with HF with reduced ejection fraction. The wearable cardioverter-defibrillator (WCD) provides continuous HR monitoring and alerts that could aid medication titration., Objective: This study sought to evaluate sex differences in achieving guideline-recommended HR control during a period of WCD use., Methods: Data from patients fitted with a WCD from 2015 to 2018 were obtained from the manufacturer's database (ZOLL). The proportion of patients with adequate nighttime resting HR control at the beginning of use (BOU) and at the end of use (EOU) were compared by sex. Adequate HR control was defined as having a nighttime median HR <70 beats/min., Results: A total of 21,440 women and a comparative sample of 17,328 men (median 90 [IQR 59-116] days of WCD wear) were included in the final dataset. Among patients who did not receive a shock, over half had insufficient HR control at BOU (59% of women, 53% of men). Although the proportion of patients with resting HR ≥70 beats/min improved by EOU, 43% of women and 36% of men did not achieve guideline-recommended HR control., Conclusion: A significant proportion of women and men did not achieve adequate HR control during a period of medical therapy optimization. Compared with men, a greater proportion of women receiving WCD shocks had insufficiently controlled HR in the week preceding ventricular tachyarrhythmia/ventricular fibrillation and 43% of nonshocked women, compared with 36% of men, did not reach adequate HR control during the study period. The WCD can be utilized as a remote monitoring tool to record HR and inform adequate uptitration of beta-blockers, with particular focus on reducing the treatment gap in women., (© 2024 Heart Rhythm Society. Published by Elsevier Inc.)

Background: Altered heart rate variability (HRV) has been associated with a number of disorders affecting autonomic tone, including recent myocardial infarction, congestive heart failure, and diabetic neuropathy. Furthermore, obstructive sleep apnea (OSA) has been shown to be associated with characteristic disturbances in heart rhythm. In this study, using HRV frequency analysis, an attempt has been made to diagnose or possibly diagnose OSA. Materials and Methods: Using Somnologica version 3.3.1 software (Medcare-Embla), polysomnographic recordings were done. Electrocardiographic signals were digitalized with a sampling rate of 250 Hz. Using the HRV analysis report of this software, low-frequency (LF) and high- frequency (HF) information and LF to HF ratio (LF/HF) were obtained at 5-min intervals, then at cutting points 30, 35, 40, 45, and 50, which indicate the intensity of the apnea and hypopnea index (AHI), were analyzed with mean and standard deviation of HRV frequencies. Results: According to the results reported in this study, comparison of mild, moderate, and severe cases led to no significant differences, while frequency-domain analysis displayed significant LF/HF increase in more severe AHI cases. This can probably be applied in screening high-risk patients, reducing the application of PSG in high probable cases, and providing an estimate of prognosis of potentials patients for the physicians. Conclusions: In the study of frequency-domain analysis, LF/HF increases in more severe AHI cases. These can probably be applied in screening high-risk patients, reducing the application of PSG in high probable cases.

Aim: To analyze the influence of the hydrogen sulfide donor NaHS on the cardiac control in rats during of low doses of ionizing radiation and characterize the predictors of imbalance in autonomic nervous system activities. Methods: Adult male rats were treated once with NaHS 7,4 mg/kg, i.p. or vehicle (saline) without and with exposure total body radiation (TBR). Heart rate variability (HRV) was recorded in rats after 30 min with NaHS pre-treatment, 24 h of TBR exposure and NaHS and TBR combination. Results: HRV analysis revealed that low doses of radiation causes cardiac autonomic dysfunction. TBR rats had signs of activation sympathetic nervous system, while NaHS-treated rats had shown mobilization of all parts of regulatory systems with predominant activation of the parasympathetic nervous system (PSNS). Taking together, this results indicate, that NaHS involves in cardiac control and decreases sensitivity to low doses of radiation. Conclusions: The gaseous messenger H2S under conditions of radiation modulates of adaptive processes, acting as a regulator for imbalance of autonomic nervous system and may serve as a novel cardioprotective agent for ANS imbalance. Key words: Hydrogen sulfide (H2S), low doses radiation (LDR), autonomic nervous system (ANS), cardiovascular system, heart rate variability (HRV), hydrogen sulfide donor (NaHS).

Abstract Background Heart rate variability (HRV) arises from the complex interplay of sympathetic and parasympathetic autonomic regulation of heart rate. Ultra-low frequency (ULF) and very-low frequency (VLF) components of HRV play a crucial role in automatic HR controllers, but these frequency bands have hitherto largely been neglected in HRV studies. The aim of this work was to investigate changes in ULF and VLF heart rate variability with respect to exercise intensity and time during treadmill running. Methods RR intervals were determined by ECG in 21 healthy male participants at rest, and during moderate and vigorous-intensity treadmill running; each of these three tests had a duration of 45 min. Time dependence of HRV was investigated for moderate and vigorous running intensities by dividing the constant-speed stages into three consecutive windows of equal duration ($$\sim$$ ∼ 14 min), denoted $$w_1$$ w1 , $$w_2$$ w2 and $$w_3$$ w3 . ULF and VLF power were computed using Lomb-Scargle power spectral density estimates. Results For both the ULF and VLF frequency bands, mean power was significantly different between the resting, moderate and vigorous intensity levels (overall $$p < 0.001$$ p

Physical training is recommended for obese paediatric populations. We investigated the effects of recreational judo training (JT) upon body composition and distribution, cardiorespiratory fitness, and heart rate variability (HRV) in overweight or obese children. A controlled trial (RBR-9d94td) was conducted with 35 children (8–13 years) assigned into groups according to their body mass index (BMI): eutrophic (EU; n = 15; z-BMI ≤ +l and ≥ −2) and overweight or obese (OB; n = 20; z-BMI > +1 and ≤ +3). The 12-week JT included 60-min sessions performed 2 times/week at 65–75% maximal heart rate (HR). BMI, waist circumference, blood pressure, HRV, peak oxygen uptake (VO2peak), gas exchange threshold (GET), and body fractioning were assessed. Significant reductions in OB (P < 0.05) occurred for whole body and trunk fat (~3%), trunk/limb fat-ratio (~4%), resting HR (~3%), and sympathovagal balance (log LF:HF, ~85%). Increases (P < 0.05) occurred in lean mass (~8%), parasympathetic modulation (log HF, ~4%), VO2peak (~5-10%), and VO2 (~15%), speed (~10%) and slope (~13%) at GET. Markers of cardiorespiratory fitness (relative VO2, slope and speed at GET) in OB approached EU after JT. In conclusion, a relatively short JT intervention to improved body composition, autonomic modulation, and physical fitness in obese children. [ABSTRACT FROM AUTHOR]

Copyright of Revista Brasileira de Medicina do Esporte is the property of Redprint Editora Ltda. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Unilateral carotid body denervation has been proposed as treatment for sympathetic-related human diseases such as systolic heart failure, hypertension, obstructive sleep apnea, and cardiometabolic diseases. The long-term therapeutic effects of carotid body removal will be maintained if the remnant "buffer nerves," that is, the contralateral carotid nerve and the aortic nerves that innervate second-order neurons at the solitary tract nuclei (NTS), do not modify their contributions to the cardiovascular chemoreflexes. Here, we studied the cardiovascular chemoreflexes 1 mo after unilateral carotid body denervation either by excision of the petrosal ganglion (petrosal ganglionectomy, which eliminates central carotid afferents) or exeresis of a segment of one carotid nerve (carotid neurectomy, which preserves central afferents). Cardiovascular chemoreflexes were induced by intravenous (iv) injections of sodium cyanide in pentobarbitone-anesthetized adult cats. After 1 mo of unilateral petrosal ganglionectomy, without significant changes in basal arterial pressure, the contribution of the contralateral carotid nerve to the chemoreflex increases in arterial pressure was enhanced without changes in the contribution provided by the aortic nerves. By contrast, after 1 mo of unilateral carotid neurectomy, the contribution of remnant buffer nerves to cardiovascular chemoreflexes remained unmodified. These results indicate that a carotid nerve interruption involving denervation of second-order chemosensory neurons at the NTS will trigger cardiovascular chemoreflex plasticity on the contralateral carotid pathway. Then, unilateral carotid body denervation as therapeutic tool should consider the maintenance of the integrity of carotid central chemoafferents to prevent plasticity on remnant buffer nerves. NEW & NOTEWORTHY Unilateral carotid body denervation has been proposed as treatment for sympathetic hyperactivity-related human disorders. Its therapeutic effectiveness for maintaining a persistent decrease in the sympathetic outflow activity will depend on the absence of compensatory chemoreflex plasticity in the remnant carotid and aortic afferents. Here, we suggest that the integrity of central afferents after carotid body denervation is essential to prevent the emergence of plastic functional changes on the contralateral "intact" carotid nerve. [ABSTRACT FROM AUTHOR]

Arterial pressure (Pa) regulation is essential to adequately distribute nutrients to metabolizing tissues, remove wastes and avoid lesions associated with hypertension. In vertebrates, short-term Pa regulation is achieved through the baroreflex, which elicits inversely proportional changes in heart rate (f H) and vascular resistance to restore Pa. The cardiac limb of this reflex has been reported in all vertebrate groups studied to date: teleosts, amphibians, snakes, lizards, crocodiles, birds and mammals – which led to the suggestion that the baroreflex is an ancient trait present in all vertebrate species. However, it is not clear whether more basal groups of vertebrates, such as cyclostomes, elasmobranchs and chondrosteans, manifest baroreflex regulation of f H. Thus, the aim of this study was to determine whether the white sturgeon (Acipenser transmontanus ; Chondrostei: Acipenseridae) exhibits a cardiac baroreflex. To do so, we induced Pa perturbations through injections of phenylephrine, sodium nitroprusside (SNP) and saline solution (hypervolemia), and examined possible f H baroreflex responses. We also investigated whether f H responses triggered by fright and chemoreflex were present in this species, in order to confirm the potential of sturgeon to perform reflexive cardiac adjustments. The findings indicate that A. transmontanus exhibits reflex bradycardia in response to fright and chemoreceptor stimulation, illustrating its capacity for short-term cardiac regulation. However, this species does not display baroreflex control of f H across its physiological range. This dissociation suggests that while the nervous and cardiovascular systems of A. transmontanus are primed for rapid reflex responses, a cardiac baroreflex mechanism remains absent. [Display omitted] • The sturgeon is capable of fast cardiac chronotropic responses via myelinated vagus. • It shows fast reflex bradycardia to chemoreflex and fright. • No sign of cardiac baroreflex could be found by blood pressure manipulation. [ABSTRACT FROM AUTHOR]

The stochastic optimal control formulation for heart rate (HR) regulation during treadmill exercise is extended here to encompass low-pass characteristics in the compensator and in the input sensitivity function. The latter governs the response of the treadmill speed command to disturbances arising from physiological heart rate variability (HRV), and it must be shaped to give appropriate control loop behaviour. In a comparative test series involving 20 healthy male subjects, the low-pass compensator was found to give substantially and significantly lower mean intensity of changes in treadmill speed (1.0 vs. $ 12.2 \times 10^{-4} $ m2/s2, low-pass vs. non-low-pass compensators, $ p = 5.1 \times 10^{-8} $ ), but at the cost of a significant increase in mean root-mean-square tracking error (2.46 vs. 1.74 bpm, $ p = 6.5 \times 10^{-6} $ ). The experimental results demonstrated accurate and robust control of HR across the 20 subjects tested, despite a simple pre-existing nominal model having been used for controller design. The results also provide strong evidence that the magnitude of HRV decreases naturally over time. The principal design issue in this application is that of suppression of disturbances arising from HRV, but changes in treadmill speed must remain acceptable to the runner. The theoretical extension of the stochastic optimal control problem formulation derived here allows this to be addressed by appropriate shaping of the key sensitivity functions using two tuning parameters, thus facilitating the tradeoff between tracking accuracy and control signal intensity.

Heart rate variability (HRV) analysis provides an assessment of cardiac vagal tone and consequently global cardiac health as well as systemic condition. In systemic diseases such as cancer and during treatments that affect the whole body, like chemotherapy, the vagus nerve activity is low and deregulated. Some studies focus on using HRV to predict mortality in oncology. However, in cancer patients, systemic alterations substantially increase artifacts during HRV measurement, especially atrial ectopic beats. Moreover, HRV may be altered by various factors (duration and time of measurement, breathing, drugs, and other confounding factors) that alter each metric in different ways. The Standard Deviation of all Normal to Normal intervals (SDNN) is the most commonly used metric to evaluate HRV in oncology, but it does not appear to be specific to the cardiac vagal tone. Thus, cardiac vagal activity diagnosis and vital prognosis of cancer patients can be biased. Our review presents the main HRV metrics that can be currently used in oncology studies and their links with vagus nerve and cancer. We present the influence of external factors and the required duration and time of measurement. Considering all these parameters, this review proposes seven key points for an assessment of HRV and cardiac vagal tone in patients with cancer., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2024 Chinese National Cancer Center. Published by Elsevier B.V.)

The aim of the study was to develop and clinically test a hardware and software system capable of identifying the predictors of the hidden forms of atrial fibrillation (AF) using 12-lead ECG data in sinus rhythm., Materials and Methods: There was developed the hardware and software system "Intecard 8.1" to assess a set of markers for atrial electrical instability by 3-5-minute ECG recordings in sinus rhythm. The markers include P-wave amplitude in lead II <0.1 mV, P-wave duration >120 ms, advanced interatrial block, the area of the biphasic P-wave terminal part <-4 mV·ms, and MVP (morphology-voltage- P-wave duration) score >3 points.The clinical testing of "Intecard 8.1" system was carried out on 120 patients with ischemic heart disease or dilated cardiomyopathy. The patients' average age was 57.9±13.1 years., Results: P-wave detection is a challenging task due to a low signal amplitude, noise, high error probability in atrioventricular block or T-wave and P-wave superposition in case of marked tachycardia. To improve detection, a phase transformation method was used, according to which there was studied its phase component arctg[ x ( n ) /Rv ], where x ( n ) - ECG signal samples, Rv - a constant. We developed an identification algorithm implemented in "Intecard 8.1" software, its clinical trials being conducted.During the 12 [6; 22] month observation period, AF episodes were recorded in 22 from 120 patients (18.3%). The patients with AF episodes exhibited a significant decrease in P-wave amplitude (p=0.029), its duration increase (p<0.001), and a significantly high MVP score (p<0.01). The MVP score with a cut-off point >3 points is of the highest prognostic significance. The area under the ROC curve AUC was 0.988 with a 95% confidence interval: 0.975-0.999 (p<0.001). The prediction model of hidden AF paroxysms has sensitivity and specificity: 92 and 89%, respectively., Conclusion: The digital electrocardiographic complex "Intecard 8.1" when analyzing 3-5-minute ECG recordings with sinus rhythm enables to identify the patients with high risk or with hidden AF forms. The dynamic assessment of P-wave parameters offers an opportunity to personalize heart rhythm control in this patient cohort., Competing Interests: Conflict of interest. The authors declare no conflict of interest related to the present study.

Background: The optimal level of heart rate (HR) control in patients with atrial fibrillation (AF) is unknown. To assess the effect of rate control on cardiopulmonary exercise capacity and quality of life (QoL) in permanent AF.Methods: One hundred forty-three patients with permanent AF were enrolled in this study. All patients received rate control medications and were followed up for 1 year. After 1-year therapy, the exercise capacity and QoL were evaluated by cardiopulmonary exercise testing (CPET) and 36-item Short-Form Health Survey, respectively. Data were compared by dividing the patients according to the following criteria: (1) whether the resting HR was ≤80 or > 80 bpm; (2) whether the exercise HR during moderate exercises on CPET was ≤110 or > 110 bpm; and (3) whether the resting HR was ≤80 bpm and exercise HR was ≤110 bpm.Results: No significant differences in peak oxygen uptake, peak metabolic equivalent, and anaerobic threshold were found between the strict control and lenient control groups. Both physical component summary (PCS) and mental component summary (MCS) were significantly higher for the strict rate control group than for the lenient control group. The single-factor correlation analysis revealed a negative correlation between resting HR and both PCS and MCS. The multivariable linear regression analysis indicated that both exercise HR and duration of AF linearly correlated with PCS and MCS.Conclusions: Therefore, in patients with permanent AF, exercise capacity may not be affected by the stringency of rate control, and strict rate control may be associated with better QoL. [ABSTRACT FROM AUTHOR]

The objective was to assess the performance and robustness of a novel strategy for automatic control of heart rate (HR) during cycle ergometry. Control design used a linear plant model and direct shaping of the closed-loop input-sensitivity function to achieve an appropriate response to disturbances attributable to broad-spectrum heart rate variability (HRV). The controller was evaluated in 73 feedback control experiments involving 49 participants. Performance and stability robustness were analysed using a separately identified family of 73 plant models. The controller gave highly accurate and stable HR tracking performance with mean root-mean-square tracking error between 2.5 beats/min (bpm) and 3.1 bpm, and with low average control signal power. Although plant parameters varied over a very wide range, key closed-loop transfer functions remained invariant to plant uncertainty in important frequency bands, while infinite gain margins and large phase margins (> 62∘) were preserved across the whole plant model family. Highly accurate, stable and robust HR control can be achieved using LTI controllers of remarkably simple structure. The results highlight that HR control design must focus on disturbances caused by HRV. The input-sensitivity approach evaluated in this work provides a transparent method of addressing this challenge. Graphical Abstract Heart rate control using a cycle ergometer. [ABSTRACT FROM AUTHOR]