Heart Rate Variability Research Articles

Cardiac health in breast cancer (CHiB): protocol for a single-centre, randomised controlled trial.

The incidence of breast cancer has increased from 900 000 to 2.3 million new annual cases over the last 25 years. The 5-year survival rate has markedly risen to over 90% worldwide due to significant therapeutic advancements. Longer survival in patients with breast cancer means more patients may experience long-term effects of their treatments, including cancer therapy-related cardiac dysfunction (CTRCD). To date, there is no established primary prevention to minimise CTRCD. The Cardiac Health in Breast Cancer study is a two-arm, single-centre, randomised controlled trial investigating the impact of an exercise programme on cardiac changes in patients with breast cancer undergoing cardiotoxic cancer therapy. 48 females with breast cancer will be randomised to either a 12-month intervention group (IG) or a control group (CG). The IG will receive a combination of supervised high-intensity interval training (HIIT) and high-intensity resistance training (HIRT) for 6 months, while the CG will follow WHO guidelines for physical activity independently. All participants will undergo transthoracic echocardiography, cardiac magnetic resonance (CMR) imaging and cardiopulmonary exercise testing at baseline, after 6 months and after 12 months. The primary endpoint is the occurrence of symptomatic or asymptomatic CTRCD at the time points of examination, detected by cardiac imaging, which may be mitigated by structured physical exercise. Secondary endpoints include assessments of cardiac inflammation as detected by CMR, mitochondrial dysfunction, health-related quality of life, the occurrence of fatigue, depression and anxiety, as well as exercise capacity, average heart rate, heart rate variability and daily physical activity.

Ferric carboxymaltose reduces the burden of arrhythmic events in heart failure with reduced ejection fraction: the role of the non-invasive arrhythmic biomarkers

BackgroundTreating iron deficiency (ID) with ferric carboxymaltose (FCM) in patients with heart failure with reduced ejection fraction (HFrEF) enhances morbidity, quality of life (QoL), and exercise capacity. MethodsThis single center, prospective follow-up study aims to assess FCM's impact on arrhythmic events and non-invasive markers in HFrEF patients with cardiac implantable electronic devices (CIEDs) and ID. Symptomatic HFrEF patients with ID and CIEDs scheduled for IV FCM were followed for 12-months. Arrhythmic activity was evaluated from CIEDs and non-invasive markers from Holter recordings pre- and post-FCM. Ventricular tachycardia/ventricular fibrillation (VT/VF) episodes, non-sustained VT (nsVT), late potentials (LPs), Microvolt T-wave alternans (MTWA), heart rate variability, turbulence (HRT) QTc, and premature ventricular contractions (PVCs, number and Lown and Wolf classification) were assessed. Left ventricular EF (LVEF), global longitudinal strain (LV GLS), QoL (KCCQ, EQ-5D-5L), six-minute walking distance (6MWD), peak oxygen consumption, and N-terminal prohormone of brain natriuretic peptide (NT-proBNP) levels were also recorded. ResultsNinety-six patients in optimal medical treatment participated (median age 71.9 [12.3] years, 83% male). Post-FCM treatment, VT/VF (P=0.043) and nsVT (P<0.001) frequency decreased significantly. The Lown and Wolf classification improved (P=0.002) and predicted VT/VF episodes better than other markers (AUC 0.737, P=.001). MTWA, LPs and HRT improved statistically significantly post-FCM. Hospitalization rates and NT-proBNP levels decreased, while LVEF, LV GLS, 6MWD, QoL and peak VO2 improved statistically significantly (P<0.001). ConclusionsOur study provides real-world evidence that IV FCM led to statistically significant reduction in ventricular arrhythmic episodes, as well as an improvement in non-invasive arrhythmic markers.

Effects of Near Infrared Radiation in Ambient Lighting on Cognitive Performance, Emotion, and Heart Rate Variability

Although sunlight contains approximately equal amounts of near-infrared radiation (NIR) and visible light, NIR is absent from most present-day electric lighting systems and is filtered by energy-efficient windows. However, NIR is biologically active and is commonly applied in targeted photobiomodulation treatments for a range of cognitive, emotional, and physical conditions. Given the removal of NIR from indoor illumination, it is critical to understand how ambient NIR may influence psychological and physical health, and whether reduced exposure to NIR in indoor environments could be cause for concern. In a preregistered within-subjects double-blind experiment, acute effects of NIR and far-red wavelengths in ambient illumination on cognition, emotional state and cardiovascular health were examined in a sample of 151 university students (117 females, 34 males). During a 2-hour laboratory session, participants were monitored at rest and while engaged in cognitively demanding tasks across two counterbalanced lighting conditions. Both included 3500 K white light generated by a light-emitting diode (LED) system, while one additionally included LEDs with peak wavelengths in the NIR (875 nm, 960 nm) and far-red (735 nm) spectrum. The addition of NIR and far-red to the ambient lighting showed beneficial effects on resting high-frequency heart rate variability (HF-HRV), HF-HRV responses to cognitive demand, and feelings of pleasure, but reduced performance on a visual search task. These findings reveal that the absence of NIR from architectural lighting influences humans at a psychological and physiological level, with implications for health and well-being that need to be balanced with energy-saving considerations.

How speech in acoustically different offices influences a working person? – Experiments in two countries

Working during task-irrelevant speech influences workers. Adequate room acoustic design can reduce the negative effects in open-plan offices, but harmonized target values do not exist. Our purpose was to examine the effects of room acoustic design levels on a working person during the exposure to task-irrelevant speech. The Finnish room acoustic regulation was chosen as a reference, as it is one of the strictest worldwide. Three room acoustic conditions were examined: regulation violated (Reg-) (Speech Transmission Index, STI=0.71), regulation fulfilled (Reg0) (STI=0.37), and regulation surpassed (Reg+) (STI=0.16). To examine the generalizability of the results, asimilar experiment was performed in two countries (two languages and laboratories): Finland and Germany (FinGer study, N=98). Experience was measured with questionnaires, performance with visual and auditory serial recall tasks, and physiological stress with heart rate variability. Results did not depend on the country, suggesting that our findings could be similar also in other countries. Speech annoyance and perceived concentration difficulty differed in each condition. With other experience measures, only Reg+ improved experience compared to the two other conditions. Visual serial recall performance was more accurate and faster in Reg+ than in Reg-. Accuracy was also improved in Reg0 compared to Reg-. The physiological stress levels did not depend on the condition. Our study shows that Reg0 was better than Reg- with respect to experience and performance but experience was further improved from Reg0 to Reg+. Therefore, it is beneficial to design room acoustics better than the Finnish regulation to maximize work performance and experience.

Effects of a synthetic analogue of the bovine appeasing pheromone on the overall welfare of dairy calves from birth through weaning

Environmental enrichment in the form of synthetic analogs of appeasing pheromones have shown promising results in improving the welfare of domestic animals including dogs, pigs, horses, and cattle. The main objective of this study was to determine if the use of the bovine appeasing pheromone (BAP) would improve the welfare of dairy calves; therefore, in this randomized controlled trial, 72 Holstein Friesian dairy calves were housed in individual hutches after birth and were randomly allocated to receive BAP or a placebo once every 2 weeks from birth through weaning. After weaning, calves were moved to group hutches according to treatment for 4 additional weeks. It was hypothesized that dairy calves treated with BAP would display fewer signs of stress compared with calves receiving the placebo during the weaning process. To operationalize stress, calves were fitted with triaxial accelerometers on the hind leg after birth, and activity levels were monitored throughout the experiment. Data on live weight gain (ADG) and cortisol levels in saliva and hair were also obtained. Calves were fitted with heart rate monitors every week for at least 24 h to assess heart rate variability (HRV). The use of BAP had a positive effect on ADG after weaning and during group housing and resulted in increased resting time after weaning. Moreover, BAP, was associated with a reduction in the activation of the neuroendocrine system evidenced by higher HRV parameters after weaning, including increased standard deviation of beat to beat of normal sinus beats (SDNN) and root mean squares of successive differences (RMSSD). These results suggest a potential welfare benefit of the use of BAP during the artificial rearing of dairy calves.

The cAMP/PKA signaling pathway conditions cardiac performance in experimental animals with metabolic syndrome

Metabolic syndrome (MetS) increases the risk of coronary artery disease, but effects of this condition on the working myocardium remain to be fully elucidated. In the present study we evaluated the consequences of diet-induced metabolic disorders on cardiac function and myocyte performance using female mice fed with Western diet. Animals maintained on regular chow were used as control (Ctrl). Mice on the Western diet (WesD) had increased body weight, impaired glucose metabolism, preserved diastolic and systolic function, but increased left ventricular (LV) mass, with respect to Ctrl animals. Moreover, WesD mice had reduced heart rate variability (HRV), indicative of altered cardiac sympathovagal balance. Myocytes from WesD mice had increased volume, enhanced cell mechanics, and faster kinetics of contraction and relaxation. Moreover, levels of cAMP and protein kinase A (PKA) activity were enhanced in WesD myocytes, and interventions aimed at stabilizing cAMP/PKA abrogated functional differences between Ctrl and WesD cells. Interestingly, in vivo β-adrenergic receptor (β-AR) blockade normalized the mechanical properties of WesD myocytes and revealed defective cardiac function in WesD mice, with respect to Ctrl. Collectively, these results indicate that metabolic disorders induced by Western diet enhance the cAMP/PKA signaling pathway, a possible adaptation required to maintain cardiac function.

Mobile Heart Rate Variability Biofeedback for Work-Related Stress in Employees and the Influence of Instruction Format (Digital or Live) on Training Outcome: A Non-Randomized Controlled Trial.

Work-related stress is a major health issue in most industrialized countries. Heart rate variability biofeedback (HRV-BfB) can promote resilience and stress coping capacity. Mobile HRV-BfB could contribute to stress prevention in the workplace. Little is known about whether the type of training, with digital or live instruction, has an impact on the training outcome. This study analyzes the psychophysiological effects of four-week workplace resilience training with mobile HRV-BfB and the influence of instruction format (digital or live) on training success. This was a prospective, three-arm, non-randomized controlled trial with parallel group design. 73 employees of a bearing and seal manufacturer (58.9% male, 86.3% full-time employment, 67.1% office workers) attended resilience training with HRV-BfB, live (n = 24) or digital (n = 19) format, or served as waitlist controls (n = 30). HRV-BfB training spanned four weeks. Participants applied resilience techniques to increase HRV using visual biofeedback. Data were collected at baseline (T0), post-intervention (T1), and another four weeks later (T2). Primary outcome measure was the Burnout scale of the Copenhagen Psychosocial Questionnaire (COPSOQ) at T1. Secondary outcome measures included further COPSOQ scales, self-reported sleep quality (Pittsburgh Sleep Quality Index, PSQI), and HRV parameters. Burnout parameters decreased significantly in HRV-BfB and waitlist. The decrease (T0-T1 and T0-T2) showed higher effect sizes in HRV-BfB (Cohen's d: 0.63; 0.69) than in waitlist (d: 0.27; 0.36). Sleep quality improved in HRV-BfB with small effect sizes (no change for waitlist). SDNN (standard deviation of beat-to-beat intervals) increased in HRV-BfB between T0 and T1 (d: 0.23;). In subgroup analysis, digital reached higher effect sizes for improvement in burnout (d: 0.87; 0.92) and sleep quality (d: 0.59; 0.64) than live learning (burnout: d: 0.43; 0.51; sleep quality: d: 0.28; 0.22). HRV-analysis revealed no differences between subgroups. Four-week mobile HRV-BfB resilience training reduced stress and burnout symptoms in employees. No significant differences were found between HRV-BfB digital or live. Hence, companies should choose the approach that fits their company profile or, if possible, offer both formats to accommodate the different needs of employees. However, findings were nonhomogeneous and should be verified by further studies.Trial Registration: ClinicalTrials.gov , NCT04897165, 05/18/2021, retrospectively registered.

Abnormal Autonomic Nervous Regulation in Patients with Globus Pharyngeus.

Globus pharyngeus could be described as a benign sensation of lump or foreign object in the throat. The etiology of the globus as a solitary syndrome is still unknown, but it is proposed that stress could have an important role in symptom emergence. To evaluate the autonomic nervous regulation in patients with globus compared to healthy controls in reaction to stress. Patients included in the study were diagnosed based on ROME IV criteria for Disorders of Gut Brain Interaction. Besides globus, the patients did not suffer any other substantial medical condition. As a control group, measurement of healthy volunteers was performed. Both groups underwent the same stress protocol assessment in the same laboratory settings. The protocol consist of two types of stressors: cold pressor test and mental arithmetic test to test different types of autonomic reactivity. Baroreflex sensitivity was significantly decreased in patients compared to controls in all phases of the protocol. Low-frequency band of systolic blood pressure variability was significantly increasedduring both stress phases in patients compared to controls. High-frequency band of heart rate variability was significantly decreased in patients compared to controls during the both of the stress phases. The results of this study shows discrete abnormalities in complex autonomic reflex control which are predominantly manifested in response to stressful stimuli indicating altered neurocardiac regulation as a reaction to stress associated with globus pharynegus. This fact could have an important role in the personalized management of globus patients such as biofeedback.

Duration of diabetes, glycemic control, and low heart rate variability: The atherosclerosis risk in communities (ARIC) study

Persons with long-standing, poorly controlled diabetes or recent hyperglycemia had the highest burden of cardiac autonomic neuropathy. Cardiac autonomic neuropathy contributed to elevated long-term incidence of cardiovascular disease and mortality even in persons with well-controlled diabetes.

HEART RATE VARIABILITY IN OFFSPRING OF NORMOTENSIVE AND HYPERTENSIVE PARENTS: A COMPARATIVE STUDY

Objective: This study aims to evaluate the differences in heart rate variability (HRV), a biomarker of autonomic nervous system, between offspring of normotensive and hypertensive parents to understand the genetic predisposition of autonomic dysfunction. Methods: This study was a cross-sectional observational study.Two groups of healthy adults, offspring of parents with hypertension (n = 50) and offspring of parents with normal blood pressure (n = 50). Short-term HRV was measured using 5-minute electrocardiogram (ECG). HRV indices such as time and frequency domainwere measured. Data were compared by using independent t-tests, with p &lt; 0.05 being considered as statistically significant. Results:The offspring of parents with hypertension showed significantly lower HRV, with SDNN (30.5 ± 8.2 ms) compared to offspring of parents with normal blood pressure (45.2 ± 7.1 ms, p &lt; 0.001). RMSSD also was significantly lower in offspring of hypertensive group. Low-frequency (LF) power was higher in offspring of parents with hypertension,while high-frequency (HF) power was significantly reduced in them compared to the normotensive group. The LF:HF ratio was higher in offspring of parents with hypertension (2.80 ± 0.85) compared to the normotensive group (1.40 ± 0.60, p &lt; 0.001), indicating sympathovagal imbalance. Conclusion: Offspring of parents with hypertension hadlower HRV, suggesting autonomic dysfunction even in the absence of clinical hypertension. These findings emphasize the potential role of genetic predisposition in the early onset of autonomic dysregulation Further studies are required to understand mechanisms contributing to these differences in HRV.

Variabilidad de la frecuencia cardiaca en caninos saludables, adultos, y residentes en hipoxia hipobárica (Bogotá, 2600 metros sobre el nivel del mar)

Heart rate variability (HRV) refers to beat-to-beat fluctuations in heart rate and represents the neurovegetative and endocrine influence on the heart. In the present study, HRV values were obtained in healthy adult canines of both sexes, residing in the city of Bogotá (2600 meters above sea level). Time-domain and frequency-domain HRV parameters were obtained using 60-minute Holter recordings. The distribution of the data was determined using the Shapiro-Wilk test. The dogs were distributed into two subgroups to study their behaviour in relation to sex and age. ANOVA and Kruskal Wallis tests were used to determine statistical differences. In general, the mean HRV values differ from those reported by other authors in studies at sea level and at lower altitudes. The differences in HRV in relation to sex were significant in the RMSSD and pNN50 parameters. There were no differences in the relationship between HRV and age.

Heart rate variability analysis for the prediction of pre-arousal during propofol-remifentanil general anaesthesia: A feasibility study.

Accidental awareness during general anaesthesia is a major complication. Despite the routine use of continuous electroencephalographic monitoring, accidental awareness during general anaesthesia remains relatively frequent and constitutes a significant additional cost. The prediction of patients' arousal during general anaesthesia could help preventing accidental awareness and some researchers have suggested that heart rate variability (HRV) analysis contains valuable information about the patient arousal during general anaesthesia. We conducted pilot study to investigate HRV ability to detect patient arousal. RR series and the Bispectral IndexTM (BISTM) were recorded during general anaesthesia. The pre-arousal period T0 was defined as the time at which the BISTM exceeded 60 at the end of surgery. HRV parameters were computed over several time periods before and after T0 and classified as "BISTM<60" or "BISTM≥60". A multivariate logistic regression model and a classification and regression tree algorithm were used to evaluate the HRV variables' ability to detect "BISTM≥60". All the models gave high specificity but poor sensitivity. Excluding T0 from the classification increased the sensitivity for all the models and gave AUCROC>0.7. In conclusion, we found that HRV analysis provided encouraging results to predict arousal at the end of general anaesthesia.

Systematic review of cognitive impairment in drivers through mental workload using physiological measures of heart rate variability.

The intricate interplay between driver cognitive dysfunction, mental workload (MWL), and heart rate variability (HRV) provides a captivating avenue for investigation within the domain of transportation safety studies. This article provides a systematic review and examines cognitive hindrance stemming from mental workload and heart rate variability. It scrutinizes the mental workload experienced by drivers by leveraging data gleaned from prior studies that employed heart rate monitoring systems and eye tracking technology, thereby illuminating the correlation between cognitive impairment, mental workload, and physiological indicators such as heart rate and ocular movements. The investigation is grounded in the premise that the mental workload of drivers can be assessed through physiological cues, such as heart rate and eye movements. The study discovered that HRV and infrared (IR) measurements played a crucial role in evaluating fatigue and workload for skilled drivers. However, the study overlooked potential factors contributing to cognitive impairment in drivers and could benefit from incorporating alternative indicators of cognitive workload for deeper insights. Furthermore, investigated driving simulators demonstrated that an eco-safe driving Human-Machine Interface (HMI) significantly promoted safe driving behaviors without imposing excessive mental and visual workload on drivers. Recommendations were made for future studies to consider additional indicators of cognitive workload, such as subjective assessments or task performance metrics, for a more comprehensive understanding.

Dynamics of Respiratory Rate and Heart Rate Variability when Performing a Cognitive Task of Two Levels of Complexity

The study examined heart rate variability (HRV) and respiratory rate during a cognitive task (reading) at two difficulty levels. Time, frequency and nonlinear analysis of HRV was used. It has been shown that both some indicators of HRV (HR, SDNN, RMSSD, SD2, SD2/SD1) and respiratory rate change with increasing mental load, however, they do not separately demonstrate significant differences at all three stages of the study. Therefore, for the first time for cognitive studies, an integral indicator was used that links the parameters of the heart with respiration – the physiological cost of activity (PhysCost), which was previously used in work with athletes when they performed physical exercises to failure. Changes in the PhysCost showed that differences between a simple and a complex task are observed at all stages of the study. Thus, it has been established that the difference in the functional state of a person in the process of performing a continuous task of two levels of complexity is most reliably revealed when using an integrative indicator connecting the activity of the respiratory system and the circulatory system.

Cardiorespiratory and circadian clock markers in intensive care unit patients.

Biological synchronized rhythmicity is a critical physiological process. The lack of synchronized rhythms, mainly those showing a circadian basis, like sleep, the heart rate (HR) and arterial blood pressure (BP), often leads to several organic challenges, usually associated with adverse outcomes. The aim of the study was to investigate whether the intensive care unit (ICU) environment favors clock genes and cardiorespiratory changes. A total of 22 critically ill patients (16 males; 72.73%) with a mean age of 60.82 ±20.07 years and well-established cardiovascular conditions were selected from ICU. Blood samples were obtained, and total RNA was isolated and reverse-transcribed into complementary DNA (cDNA). A quantitative polymerase chain reaction (qPCR) was performed to assess the target gene expression levels. The urinary concentration levels of melatonin (MEL) were assessed. The heart rate, BP (systolic - SBP, diastolic - DBP and mean - MBP) and the oxygen saturation (SpO2) levels were assessed as continuous variables. The urinary MEL and Brain and muscle Arnt-like protein-1 (BMAL1) levels were shown to have a non-linear relationship with HR (coefficient (coef): 2.318, p = 0.032; coef: 2.722, p = 0.006, respectively) and SBP (coef: 1.000, p = 0.008; coef: 2.000, p = 0.037, respectively), with an explanatory power of up to 50.3% and 39.7% of the HR and SBP variability, respectively. Melatonin, but not BMAL1, was also shown to have a non-linear relationship with MBP (coef: 1.000, p = 0.007), with an explanatory power of up to 31.3% regarding the MBP variability. The HR and SBP oscillatory dynamics was shown to be related to changes in the genetic expression of BMAL1 and the urinary MEL concentrations. To a lower degree, MEL also impacted the variation of MBP. Our results suggest that not only are circadian functional matrices crucial for the dynamics of vital parameters in critically ill patients, but also that routinely assessed cardiovascular parameters like HR and BP may constitute important markers for the circadian timing system function. These parameters are easy to assess and have a relevant prognostic value regarding recovery outcomes, as well as the morbidity and mortality rates in ICU.

Relationship between autonomic and peripheral neuropathies and cardiovascular outcomes in diabetes

This review explores the complex relationship between diabetic neuropathy and cardiovascular disease (CVD). Neuropathy, a common complication of type 1 and type 2 diabetes, is divided into autonomic and peripheral types, each impacting cardiovascular health. Cardiovascular autonomic neuropathy, a form of autonomic neuropathy, is associated with various CVD complications, including arrhythmias, impaired nocturnal blood pressure regulation, and increased mortality. The prevalence of cardiovascular autonomic neuropathy varies depending on the type and duration of diabetes and is influenced by factors like glycemic control and metabolic stress. Peripheral polyneuropathy, which is often linked to diabetic foot disease, is also correlated with elevated CVD risk; research suggests shared pathophysiological mechanisms between peripheral neuropathy and cardiovascular conditions. Screening for neuropathies using tools like the Michigan Neuropathy Screening Instrument and heart rate variability analyses can facilitate early detection of CVD risk. Additionally, emerging technologies, like deep learning models, have demonstrated promise in detecting early cardiovascular patterns associated with autonomic neuropathy through electrocardiogram analysis. These findings underscore the value of integrating novel diagnostic approaches for early intervention. As CVD represents a leading cause of death among patients with diabetes, this article emphasizes the need for thorough assessment and proactive management of neuropathy to mitigate cardiovascular risk. The review recommends a multidisciplinary approach to diabetes care, including early screening, accurate risk stratification, and targeted therapeutic strategies to prevent or slow the progression of CVD in patients with autonomic and peripheral neuropathies. Further research is warranted to clarify the optimal intervention strategies for reducing CVD risk in these populations.

A Cross-Sectional Study on the Effect of Stress on Short-Term Heart Rate Variability and Muscle Strength Among Construction Site Workers

This cross-sectional study investigates the immediate impact of occupational stress on short-term heart rate variability (HRV) and muscle strength among 200 construction workers in Chennai. The Perceived Stress Scale (PSS) was employed to assess stress levels, while HRV was measured using a portable ECG device, focusing on time-domain (RMSSD) and frequency-domain (HF Power) parameters. Muscle strength was evaluated using a MicroFET 2 dynamometer. Pearson correlation and multivariate regression analyses were applied to determine the associations between stress, HRV, and muscle strength, adjusting for confounding factors such as age, body mass index (BMI), and work duration. Results revealed a significant negative correlation between perceived stress and both HRV indices (RMSSD: r=-0.45, p&lt;0.01; HF Power: r=-0.50, p&lt;0.01) as well as muscle strength (r=-0.40, p&lt;0.01). Higher stress levels were associated with reduced HRV and diminished muscle strength. Regression analyses confirmed that stress independently predicted lower HRV (RMSSD: ?=-0.35, p&lt;0.01; HF Power: ?=-0.42, p&lt;0.01) and decreased muscle strength (?=-0.32, p&lt;0.01). These findings suggest that elevated stress negatively impacts both cardiovascular and muscular functioning, potentially increasing the health risks among construction workers. The study highlights the importance of implementing stress management interventions to improve both the physical well-being and productivity of workers in the construction industry.

Physiological Predictors of Operator Performance: The Role of Mental Effort and Its Link to Task Performance.

The present study investigated how pupil size and heart rate variability (HRV) can contribute to the prediction of operator performance. We illustrate how focusing on mental effort as the conceptual link between physiological measures and task performance can align relevant empirical findings across research domains. Physiological measures are often treated as indicators of operators' mental state. Thereby, they could enable a continuous and unobtrusive assessment of operators' current ability to perform the task. Fifty participants performed a process monitoring task consisting of ten 9-minute task blocks. Blocks alternated between low and high task demands, and the last two blocks introduced a task reward manipulation. We measured response times as primary performance indicator, pupil size and HRV as physiological measures, and mental fatigue, task engagement, and perceived effort as subjective ratings. Both increased pupil size and increased HRV significantly predicted better task performance. However, the underlying associations between physiological measures and performance were influenced by task demands and time on task. Pupil size, but not HRV, results were consistent with subjective ratings. The empirical findings suggest that, by capturing variance in operators' mental effort, physiological measures, specifically pupil size, can contribute to the prediction of task performance. Their predictive value is limited by confounding effects that alter the amount of effort required to achieve a given level of performance. The outlined conceptual approach and empirical results can guide study designs and performance prediction models that examine physiological measures as the basis for dynamic operator assistance.

A Review of Factors Affecting Radiation Dose and Image Quality in Coronary CTA Performed with Wide-Detector CT

Compared with traditional invasive coronary angiography (ICA), coronary CT angiography (CCTA) has the advantages of being rapid, economical, and minimally invasive. The wide-detector CT, with its superior temporal resolution and robust three-dimensional reconstruction technology, thus enables CCTA in patients with high heart rates and arrhythmias, leading to a high potential for clinical application. This paper systematically summarizes wide-detector CT hardware configurations of various vendors routinely used for CCTA examinations and reviews the effects of patient heart rate and heart rate variability, scanning modality, reconstruction algorithms, tube voltage, and scanning field of view on image quality and radiation dose. In addition, novel technologies in the field of CT applied to CCTA examinations are also presented. Since this examination has a diagnostic accuracy that is highly consistent with ICA, it can be further used as a routine examination tool for coronary artery disease in clinical practice.

Chronic rose oxide and exercise synergistically modulate cardiovascular and autonomic functions in hypertensive rats.

With the alarming rise in cases of arterial hypertension worldwide, there is an urgent need to develop combined therapies to mitigate this scenario. Rose oxide (RO), a monoterpene with anti-inflammatory and hypotensive properties, emerges as an alternative. The present study is the first to evaluate the effect of RO administered chronically and combined with physical exercise (swimming) since both have been reported to have beneficial impacts on hypertension. Male SHR and Wistar rats (aged 12weeks) received RO for 34 consecutive days (orally; 100mg/kg). The progression of systolic arterial pressure (SAP) was monitored through tail-cuff plethysmography. Twenty-four hours before the end of the treatment, the animals were anesthetized, and the femoral artery and vein were cannulated to record the pulsatile arterial pressure and to administer drugs, respectively. Hemodynamic and autonomic parameters and baroreflex sensitivity and intrinsic heart rate (IHR) were evaluated. Treatment with RO, administered alone or combined with exercise, reduced SAP and mean arterial pressure in SHR. The swimming protocol did not prevent increases in BP, but when combined with RO, it improved autonomic control, assessed through heart rate variability and parasympathetic tone. IHR was attenuated in SHR, and none of the treatments reversed this response. Therefore, combining RO with physical exercise may enhance their antihypertensive effects, improving autonomic function, reducing oxidative stress and inflammation, providing synergistic cardiovascular benefits, improving metabolic health, promoting a comprehensive lifestyle intervention, and potentially allowing for reduced medication dosages. This multifaceted approach could offer a more effective and sustainable strategy for managing hypertension.