Increase In Heart Rate Research Articles

Increased sound levels in the cardiac ICU are associated with an increase in heart rate, blood pressure, and sedation.

Several organizations including the Environmental Protection Agency, World Health Organization and American Academy of Pediatrics recommend that hospital sound levels not exceed 45 decibels. Yet, several studies across multiple age groups have observed higher than recommended levels in the intensive care setting. Elevated sound levels in hospitals have been associated with disturbances in sleep, patient discomfort, delayed recovery, and delirium. We measured sound levels in a pediatric cardiac intensive care unit and collected vital signs data, sedation dosing and delirium scores. During a 5-week study period, sound levels for 68 patients in 22 private and 4 semi-private rooms were monitored. Sound levels were consistently above stated recommendations with an average daytime level of 50.6 decibels (maximum, 76.9 decibels) and an average nighttime level of 49.5 decibels (maximum, 69.6 decibels). An increase in average and maximum sound levels increased the probability of sedation administration the following hour (p-value < 0.001 and 0.01, respectively) and was predictive of an increase in heart rate and blood pressure (p-value < 0.001). Sound levels in the CICU were consistently higher than recommended. An increase in heart rate, blood pressure and sedation utilization may suggest a stress response to persistent and sudden loud sounds. Given known negative impacts of excessive noise on stress, sleep, and brain development, as well as the similar adverse effects from the related use of sedative medications, reducing excessive and sudden noise may provide an opportunity to improve short- and long-term hemodynamic and neurodevelopmental outcomes in the pediatric cardiac intensive care unit.

Acute GLP-1 Agonism Induces Arrhythmogenic Electrical Activity in Aged Mice Heart Through Impaired Cellular Na+ and Ca2+ Handlings: TheRole of CK2 Hyperphosphorylation.

Glucagon-like peptide-1 receptor agonists (GLP-1RAs) are known for their benefits in conditions like cardiovascular diseases in type 2 diabetes and obesity. They also show promise for aging-related conditions with minimal side effects. However, their impact on cardiovascular risk is still debated. Notably, some long-acting GLP-1RAs cause a sustained increase in heart rate on the first day of use without a clear mechanism. To understand their short-term effects, we examined acute GLP-1R agonism on the electrical activity of elderly hearts. In this study, we utilized in vivo electrocardiography, in vitro cellular electrophysiology experiments, and biochemical measurements on heart preparations from 6-month-old (Adult) and 24-month-old (aged) BALB/c mice. A single liraglutide injection (0.3 mg/kg) induced repetitive, self-sustained arrhythmogenic electrocardiograms in aged mice (24 months old) but had no effect on adults (6 months old) within the first 10 minutes. Acute application of liraglutide to isolated ventricular cardiomyocytes from aged mice significantly prolonged the late phase of action potential repolarization (APR90). This was due to suppressed K+ currents and increased persistent Na+currents (Late-INa), primarily through delayed recovery from inactivation of Na+ currents. Additionally, liraglutide increased Ca2+ spark frequency and wave formation by enhancing Ca2+ release from the sarcoplasmic reticulum, affecting both Na+ and Ca2+ regulation in aging cells. Liraglutide also induced casein kinase 2 (CK2) hyperphosphorylation in aged cardiomyocytes, which a CK2 inhibitor could reverse, normalizing APR90 by reducing Late-INa and enhancing K+ currents. These findings reveal that acute GLP-1R agonism can disrupt electrical signaling and induce arrhythmia in aged mice through CK2 hyperphosphorylation, providing new insights into the cardiovascular effects of GLP-1RAs in the elderly.

Safety of Vericiguat in Patients with Coronary Artery Disease: A Systematic Review and Meta-analysis.

This study aimed to investigate the safety of vericiguat in patients with coronary artery disease. We conducted a comprehensive literature review of the PubMed, ClinicalTrials.gov, and Cochrane Library databases up to 27 March 2024. We included studies that compared vericiguat with placebo in patients with coronary artery disease. Clinical data were extracted, and adverse events were analyzed using Review Manager software (version 5.4) after conducting a quality assessment of the enrolled studies. Three randomized controlled trials involving 151 patients were included in this meta-analysis. Compared with the placebo group, vericiguat treatment resulted in a decrease in systolic blood pressure by 1.4-10 mmHg and diastolic blood pressure by 0.4-6 mmHg, along with an increase in heart rate by 1.8-7 bpm, all of which are clinically insignificant. Vericiguat treatment demonstrated no significant serious adverse events [odds ratio (OR) = 1.97; 95% confidence interval (CI) = 0.39-9.91; P = 0.41]. However, a significant difference in adverse events between the two groups was noted (OR = 4.04; 95% CI = 2.17-7.52; P < 0.001). This meta-analysis suggests that vericiguat is a safe drug for use in patients with coronary artery disease; however, further clinical trials are needed to validate these findings. The study protocol has been prospectively registered in PROSPERO (CRD42024528105).

Impact of electronic cigarette vaping on the cardiovascular function in young and old rats

BackgroundWhile the acute exposure to electronic cigarette (E-cig) vapor has been associated with an increase in blood pressure, the chronic effect of E-cig vapor on blood pressure compared to standard cigarette smoke has not been extensively studied. We determined the effect of E-cig exposure on blood pressure and other measures of cardiac function in both young and old rats.MethodsYoung Sprague Dawley rats (6 weeks old, both sexes) were randomly exposed to air (n = 34), E-cig with nicotine (E-cig Nic+; n = 30), E-cig without nicotine (E-cig Nic-; n = 28) or standard cigarette smoke (n = 27). Old Fischer 344 rats (25 months old, both sexes) were randomized into 2 groups: (1) 26 rats in the purified air (negative control) group and (2) 17 rats in the electronic cigarette vapor plus nicotine group (E-cig Nic+). After 12 weeks of exposure, hemodynamics were determined by Millar catheter, echocardiography, and thermodilution catheter, a few days after their last exposure.ResultsIn young rats, cigarette smoke was associated with higher systolic, diastolic and mean blood pressures and peak LV systolic pressure, compared to air or E-cig Nic + or E-cig Nic- groups. Neither fractional shortening nor cardiac output differed among the groups. Absolute value for dp/dt min, a measure of diastolic LV function, was lowest in the E-cig Nic- group. Tau, a measure of LV relaxation was worse in this group as well. In old rats, E-cig vaping did not change heart rate, blood pressure, and cardiac function. However, E-cig Nic + exposure was associated with a greater heart weight/BW and LV weight/BW compared to air exposure in old rats.ConclusionsChronic exposure to E-cig vaping did not cause an increase in blood pressure or heart rate, nor did it change cardiac function compared to air in young rats after 12 weeks of exposure, while standard cigarette smoking was associated with an increase in blood pressure. E-cig vaping was associated with a greater heart weight/BW and LV weight/BW compared to air exposure in old rats, suggested that older animals might be more vulnerable to E-cig stimulus than younger ones.

Cardiovascular Function and Autonomic Regulation in Urethane Anesthetized and Conscious Mice.

Urethane is widely used for its ability to induce prolonged anesthesia. Variability in previously reported cardiovascular parameters in murine models makes it challenging to definitively evaluate the cardiovascular effects of urethane anesthesia. We aimed to address these challenges, thereby advancing our understanding of urethane's effects on cardiovascular function in mice. In this study, we investigated how urethane anesthesia, with and without supplemental oxygen, impacts heart rate, arterial oxygen saturation (SpO2), blood pressure, and heart rate variability in mice. First, we conducted a literature review and found that data in mice was both limited and lacking in reproduction. Next, we conducted a series of physiological measurements to address gaps in the literature and subjected C57BL/6J mice to three conditions: 1) conscious, 2) urethane-anesthetized, and 3) urethane-anesthetized with supplemental oxygen. Blood pressure, heart rate, SpO2, and heart rate variability (via time, frequency, and M-curve analyses) were assessed. We observed an increase in heart rate with urethane anesthesia (p=0.012) compared to the conscious state. Urethane caused a decrease in heart rate variability which was independent of oxygen supplementation. Urethane anesthesia significantly reduced arterial blood pressure (p<0.001) with oxygen-supplemented mice remained hypotensive. Urethane decreased SpO2 (p=0.001), which was restored by oxygen supplementation (p<0.001). We did not observe sex effects of urethane anesthesia on blood pressure, heart rate, heart rate variability, or SpO2. Taken together, these results underscore the importance of a cautious approach when using urethane in mice, as urethane significantly impacts arterial blood pressure, heart rate, oxygen saturation, and heart rate variability.

Assessment of electrophysiological mechanisms of ventricular ectopia in arrhythmogenic right ventricular dysplasia

Relevance of the problem. Arrhythmogenic right ventricular dysplasia (ARVD) is one of the significant causes of sudden cardiac death (SCD) among young people. ARVD is characterized by premature ventricular ectopic contractions (PVCs) from the right ventricular outflow tract (RVOT), which may occur before morphological changes appear and, in these cases, it is necessary to assess the risk of developing SCD based on an analysis of the electrophysiological mechanism of the development of PVCs. Purpose of the study. To evaluate the electrophysiological mechanisms of PVCs in patients with ARVD according to stress tests. Material and methods. We examined 13 patients with confirmed ARVD on MRI, including 9 men and 4 women, aged from 26 to 63 years (42.9±11.0). All patients underwent the following studies: standard electrocardiography (ECG), 24-hour ECG monitoring, echocardiography, cardiac MRI, treadmill stress test. During the stress test, at each load level, ventricular ectopy was analyzed (morphology, number of ventricular ectopic complexes), and the dependence of corrected QTc on heart rate was assessed. Results. According to the data obtained, the patients were divided into two groups depending on the response of PVCs to physical activity. The first group – patients in whom the number of PVCs increased during physical activity – stress-induced ventricular ectopy – 10 people (77%). The second group – patients in whom the number of PVCs decreased, or they disappeared at the peak of the load – stress-inhibited ventricular ectopy – 3 people (23%). All patients had a normal reaction of the QT interval to physical activity – its shortening in response to an increase in heart rate. Conclusions. ARVD is characterized by ventricular ectopia from the right ventricle outflow tract or bifocal ectopia from the right ventricle outflow tract and the right ventricle apex. The electrophysiological mechanisms of ventricular ectopia in ARVD are different: the mechanism of trigger activity and increased automaticity.

Teacher stress in social interactions in the light of polyvagal theory. An ambulatory assessment approach to teachers’ heart rate and heart rate variability

BackgroundTeaching is a genuinely social and highly demanding task. Drawing on Porges’ phylogenetic polyvagal theory with three evolved systems and three associated behavioral responses (social engagement, mobilization, and immobilization), we investigated teachers’ heart rate and heart rate variability in social interactions using ambulatory assessments.MethodsWe continuously measured heart rate and heart rate variability of 42 apparently healthy teachers on a work and leisure day with ambulatory electrocardiogram. We videotaped four consecutive, same-day lectures of each teacher. We trained observers to code student aggression and frontal teaching behaviors in an event sampling procedure with the behavior observation system for analyzing aggressive behavior in school settings. Additionally, perceived teacher-student relationship, social support from other teachers / school management, occupational complaints, and vital exhaustion were assessed by teacher self-reports.ResultsTeachers showed an increased heart rate and a decreased heart rate variability on a workday compared to a leisure day, anticipatory stress before classes, as well as insufficient recovery during lunchtime. Observed student aggression and high proportion of frontal teaching were associated with lower heart rate variability, while better perceived teacher-student relationship was correlated with higher heart rate variability. Differently, teachers’ psychological strain and heart rate variability were unrelated to each other.ConclusionCorresponding to polyvagal theory, results suggest that successful social interactions are fundamental for teachers’ favorable cardiological reactions.

Development and Preliminary Testing of the Withdrawal Assessment Tool-Alpha 2 Agonist: An Assessment Instrument for Monitoring Iatrogenic Withdrawal Symptoms in Children Receiving an Alpha-2 Agonist

Objectives: To develop and conduct preliminary testing of the Withdrawal Assessment Tool-Alpha 2 Agonist (WAT-A2A) to monitor dexmedetomidine and clonidine withdrawal symptoms in acutely ill children. Design: Three-phase instrument development study. Phase 1: retrospective chart review of symptoms exhibited by children with documented dexmedetomidine withdrawal; phase 2: WAT-A2A instrument construction based on phase 1 data; and phase 3: prospective testing of the WAT-A2A in children weaning from alpha 2 agonists (A2As). Setting: Academic free-standing children’s hospital. Patients: Acutely ill children weaning from at least 5 days of dexmedetomidine. Excluded were children concurrently weaning other sedatives. Interventions: None. Measurements and Main Results: Phase 1: In 83 of 303 children weaning from at least 5 days of dexmedetomidine who had clinician documentation and were managed for A2A withdrawal, 88% (n = 72) exhibited at least a 20% increase in heart rate (HR), 83% (n = 69) exhibited agitation or change in usual state behavior, 46% (n = 38) exhibited at least a 20% increase in diastolic blood pressure (DBP), and when documented, 56% (27/48) exhibited tremors during their A2A withdrawal episode. Phase 2: The WAT-A2A was constructed, based on phase 1 data, and includes four items: HR, state behavior, DBP, and tremors. Phase 3: The WAT-A2A was tested and performed well in 82 children weaning from A2A. The total WAT-A2A score correlated with clinician subjective assessment of A2A withdrawal (Spearman correlation = 0.5; p &lt; 0.001). Inter-rater agreement, comparing paired ratings of prospectively collected WAT-A2A data, indicated moderate inter-rater reliability. Conclusions: Acutely ill children receiving sedation with an A2A for more than 5 days may develop physiologic dependence, requiring gradual dosing reductions. While further psychometric testing is advised, the WAT-A2A provides an objective instrument to help clinicians quantify dexmedetomidine withdrawal symptoms in acutely ill children may facilitate A2A weaning and limit unnecessary variation in practice.

Comparison of 2 Methods for Measuring Chronotropic Response to Exercise: Heart Rate–Work Rate Slope Versus Percent Change in Heart Rate–Work Rate Slope—A Cross-Sectional Study

Purpose: Chronotropic response to exercise (CRE) is an indicator of cardiovascular health and is evaluated using different methodologies. The purpose of this cross-sectional investigation was to compare 2 methods for measuring CRE: heart rate (HR)–work rate slope versus percent change in HR–work rate slope. Methods: Thirty-three participants met the inclusion criteria. Participants completed a two-stage graded exercise protocol. Heart rate and work rate data were recorded at rest (0 watts), the final minute of stage 1, and the final minute of stage 2. Heart rate–work rate slope was defined as the slope of HR increase relative to work rate increase. Percent change in HR–work rate slope was calculated as the percent change in HR–work rate slope between stage 1 and stage 2. Results: Spearman correlation coefficient indicated a significant, but relatively low, correlation between the 2 measurements (rs = 0.388, P = .01). The 95% limits of agreement (z-scores) between the 2 measurements were −2.29 to 2.29, suggesting considerable disagreement. Conclusions: The findings of this study indicated that HR–work rate slope and percent change in HR–work rate slope were not comparable. The low correlation and lack of agreement between the 2 methods could be explained by the possible measurement of different constructs (cardiorespiratory fitness vs coronary artery disease risk). Because of considerable disagreement, clinicians should not make decisions related to patient care using the 2 methodologies interchangeably. The findings of this investigation support the perspective that a standardized procedure for measuring CRE is warranted.

Effectiveness of Endorphin Massage and Positive Affirmations in Reducing Anxiety Levels Among Pre-Sectio Caesarea Patients

Introduction: Facing a Caesarean section (C-section), patients often imagine the surgical process and various discomforts, leading to anxiety. Anxiety can result in both physical and psychological changes, such as an increased heart rate, elevated blood pressure, rapid breathing, fatigue, and an increase in fetal heart rate. Endorphin massage and positive affirmations offer benefits such as comfort and pain relief. This sense of relaxation and comfort is expected to reduce the anxiety experienced by patients before delivery. Objective: This study aimed to evaluate the effectiveness of endorphin massage and positive affirmations in reducing anxiety levels among pre-C-section patients. Method: This experimental study employed a pre-experimental design with a one-group pretest-posttest approach. The respondents included 30 pre-C-section patients at Sayang Hospital, Cianjur, selected through a total sampling technique. The research instrument used was the Hamilton Anxiety Rating Scale (HARS) questionnaire, which assessed the patients' anxiety levels before and after the intervention. Result: The study results, analyzed using the Paired Samples T-Test, showed a p-value of 0.000, which is &lt;0.05. Conclusion: The findings indicate a significant reduction in anxiety levels among pre-C-section patients before and after receiving endorphin massage and positive affirmation interventions.

Surgeon experience affects perioperative pain in cats undergoing elective ovariohysterectomy: a randomized clinical trial.

This study aimed to compare the outcomes between surgeries performed by either experienced or inexperienced surgeons by assessing intraoperative nociception and perioperative analgesia. 16 healthy, client-owned female cats were randomly allocated into 2 groups of 8: one undergoing surgery by an experienced surgeon (GES group) and the other by inexperienced surgeons (GIS group). Both groups received IM premedication with acepromazine (0.05 mg/kg) and methadone (0.3 mg/kg). After 20 minutes, venipuncture and induction with propofol (dose-response, IV) were performed. Maintenance was achieved with inhaled isoflurane. Intraoperative vital parameters were monitored, and fentanyl (2.5 µg/kg, IV) was administered as rescue analgesia when needed. Postoperatively, pain was assessed with a visual analog scale and the multidimensional pain scale of the Universidade Estadual Paulista in Botucatu; morphine (0.2 mg/kg, IM) was used for rescue analgesia, as necessary. In the GIS group, significant increases in heart rate and systolic blood pressure were noted during surgery, especially during pedicle clamping. Respiratory rate and end-tidal isoflurane levels were higher in the GIS group at specific surgical stages. Survival analysis indicated that the GIS group had a greater need for fentanyl. Postoperative pain scores were generally low, but a higher proportion of GIS cats required rescue analgesia. Surgeon experience influences intraoperative parameters and fentanyl consumption. Inexperienced surgeons contribute to increased postoperative pain and poorer wound healing outcomes in cats undergoing elective ovariohysterectomy. Ovariohysterectomy is a common procedure in veterinary practice, and surgical expertise significantly impacts pain management and recovery. Yet, its effects have been underexplored, potentially compromising animal welfare.

Cadence-based energy expenditure in able-bodied male people comparing cadence-based energy expenditure and oxygen cost indices in able-bodied male people.

Walking is a fundamental aspect of daily life and exercise, with clinical benefits for cardiovascular health and muscle strength. However, accurately measuring energy efficiency during walking poses challenges due to equipment and spatial constraints. In this study, we proposed the cadence-based energy expenditure index (cEEI) and analyzed its correlation with the previously proposed index for measuring energy expenditure under various gait conditions. We enrolled 15 healthy participants and conducted an experimental protocol on a treadmill to measure the following energy expenditure-related indices: oxygen cost index (OCI), energy expenditure index (EEI), and cEEI. The participants underwent stages of walking at different speeds and inclinations that comply with the modified Bruce protocol, whereas their heart rate, oxygen uptake, and cadence were recorded. Participants showed significant increases in heart rate, oxygen uptake, and cadence with higher walking speeds and inclinations. Correlation analysis revealed strong associations between cEEI and OCI, especially during walking conditions. Bland-Altman plots and interclass correlation coefficient analysis demonstrated a favorable agreement between cEEI and OCI, outperforming EEI. In conclusion, this study proposes cEEI as a reliable metric for estimating energy expenditure during walking by proving a strong correlation and agreement with OCI across various gait conditions. This suggests the potential for cEEI to provide real-time, individualized feedback on energy expenditure during walking, facilitating more personalized exercise prescriptions.NEW & NOTEWORTHY We proposed cEEI as a reliable metric for estimating energy expenditure under various walking conditions. Its demonstrated accuracy and potential for real-time individualized feedback could revolutionize personalized exercise prescriptions for diverse sexes and age groups, as well as individuals with disabilities requiring real-time physical monitoring and home care.

Gestational hypoxia elicits long-term cardiovascular dysfunction in female guinea pigs

BackgroundGestational hypoxia (GH) has been implicated in the developmental programming of cardiovascular diseases (CVDs) in the offspring, with most studies focusing on males, conversely, the effects on female cardiovascular health remain understudied. We aimed to investigate the impact of GH on the cardiovascular system of female guinea pig offspring from the early postnatal period to adulthood. MethodsPregnant guinea pigs were subjected to normoxic or hypoxic conditions from gestational day 30 until delivery (∼70 days). Female offspring were monitored with biometric parameters and peripheral vascular function (ultrasound) from birth to one year old. In addition, we assessed cardiovascular structure, oxidative stress, inflammatory state (IHC, qPCR, and immunoblot assays), and thoracic aorta reactivity (wire-myography) at one year of age. Key findingsGH increased heart rate and peripheral pulsatility index. At one year old, GH-exposed females exhibited cardiac remodeling, characterized by increased left ventricular luminal area and coronary artery muscle occupation. Furthermore, GH increased aortic vascular wall, intima-media thickness and contractile capacity. This was accompanied by reduced endothelium-dependent vasodilation and enhanced oxidative stress. Additionally, GH increased collagen deposition and oxidative stress in the right ventricle, accompanied by reduced antioxidant enzymes expression and reduced inflammatory mediator levels. SignificanceGH exerts long-lasting effects on the cardiovascular health of female guinea pig offspring, contributing to cardiac remodeling, vascular dysfunction, oxidative stress, and inflammatory changes. These findings highlight the importance of GH as a risk factor for developing CVDs in female offspring and emphasize the need for sex-specific interventions to mitigate adverse long-term gestational effects.

Efficacy of a 6-week VR exergame for older adults with essential hypertension: a randomized controlled pilot trial

This study aimed to examine the initial efficacy of a virtual reality (VR) exergame for blood pressure (BP), body composition, lung function, physical working capacity, and mobility in older hypertensive adults. Furthermore, the objective was to explore the exercise intensities that can be reached during the training. This study was designed as a randomized controlled pilot trial. The exergame group (EG) completed 6-week training using VR; the conventional training group (CTG) performed conventional group training over the same time period. The sample included thirty-five participants with essential hypertension randomized with a ratio of 2:1 to EG (n = 23) and CTG (n = 12). The training was performed twice a week and consisted of strength endurance and endurance training sessions in alteration, which lasted from 20 to 30 min. Within the groups, systolic and diastolic BP were significantly reduced only in the EG. There were no group differences with regard to BP. The heart rate (HR) results showed no significant differences within and between groups in the pre–post comparison. Overall, a significant increase in HR during exercise was observed in both groups. On average, only the EG was able to reach the target intensity of 40–60%. In addition, blood pressure was significantly lower 5 min after training in EG than in CTG. This pilot study showed that 6 weeks of training with VR can lead to reaching the target heart rate during exercise and indicate a greater reduction in BP after training in older adults with hypertension. This pilot study provides useful insights into the potential of VR exergaming and for future research.

Relationship Between Heart Rate and Perceived Stress in Intensive Care Unit Residents: Exploratory Analysis Using Fitbit Data.

Intensive care unit (ICU) residents are exposed to high stress levels due to the intense nature of their work, which can impact their mental health and job performance. Heart rate measured through wearable devices has the potential to provide insights into residents' self-reported stress and aid in developing targeted interventions. This exploratory study aims to analyze continuous heart rate data and self-reported stress levels and stressors in ICU residents to examine correlations between physiological responses, stress levels, and daily stressors reported. A secondary data analysis was conducted on heart rate measurements and stress assessments collected from 57 ICU residents over a 3-week period using Fitbit Charge 3 devices. These devices captured continuous physiological data alongside daily surveys that assessed stress levels and identified stressors. The study used Spearman rank correlation, point-biserial correlation analysis, 2-tailed paired t tests, and mixed-effect models to analyze the relationship between heart rate features and stress indicators. The findings reveal complex interactions between stress levels and heart rate patterns. The correlation analysis between stress levels and median heart rate values across different percentile ranges showed that lower percentile heart rates (bottom 5%, 10%, 25%, and 50%) had modest correlations with stress, whereas higher percentiles (top 50%, 25%, 10%, and 5%) did not correlate significantly (all P>.05). The 2-tailed paired t test indicated significant differences in stress levels reported in midday versus end-of-day surveys (P<.001), although these changes in stress levels were not consistently reflected in heart rate patterns. Additionally, we explored and found that stressors related to "other health" issues had the highest positive correlation with stress level changes from midday to end-of-day surveys. However, the weak effect of these stressors on peak heart rate suggests that their impact on physiological measures like heart rate is not yet clear. According to our mixed-effects model, stress levels significantly influenced heart rate variations when hierarchical data were taken into account (P=.03), meaning that as the stress level increased, there was a significant increase in mean heart rate. This study highlights the complexity of using heart rate as an indicator of stress, particularly in high-stress environments like the ICU. Our findings suggest that while heart rate is found to correlate with self-reported stress in the mixed-effect model, its impact is modest, and it should be combined with other physiological and psychological measures to obtain a more accurate and comprehensive assessment of residents' stress levels.

Can standing replace upright tilt table testing in the diagnosis of postural tachycardia syndrome (POTS) in the young?

We compared standing and upright tilt in patients with postural tachycardia syndrome (POTS) and healthy volunteers to determine whether standing accurately tests for POTS in youngsters < 19years. POTS in adolescents is defined by orthostatic intolerance plus sustained excessive upright tachycardia, without hypotension during upright tilt. We examined whether active standing is a valid classifier for POTS in adolescents compared to tilt. Patients with POTS (N = 36, 12.2-18.8years) and healthy volunteers (N = 39, 13.1-18.9years) performed stand for a minimum of 5-min and were tilted to 70° for 10min. Receiver operating characteristics analyses (ROC) were performed at 5-min stand, and at 5 and 10min tilt for optimal threshold for heart rate (HR) increase (ΔHR), and test sensitivity and specificity. Most subjects were unable to stand for 10min. ΔHRs at 5min stand were higher in POTS (31 ± 3) compared with control (21 ± 2) and elevated at 5- or 10-min tilt in POTS (51 ± 3 and 51 ± 2) versus control (26 ± 2 and 25 ± 2) compared with standing. ΔHR in POTS and controls for 10min were not different from 5min. For 5min stand ROC threshold was 26beats per min (bpm), sensitivity of 70.6%, and specificity of 68.2% compared with 39bpm, 88.2%, and 95.1% for 5min tilt, and 40bpm, 94.1%, and 95.1% for 10-min tilt. A precision-recall graph confirmed the superior discriminating ability of 5min and 10min tilt compared to 5min stand. The stand test is relatively non-specific and imprecise compared to tilt and does not satisfactorily distinguish POTS from control in patients aged < 19years old.

Cardiorespiratory Responses to Flywheel-Based Inertial Training Squats With Varying Moments of Inertia.

Mitchinson, CJ, Best, S, Caruso, J, and Bollinger, LM. Cardiorespiratory responses to flywheel-based inertial training squats with varying moments of inertia. J Strength Cond Res XX(X): 000-000, 2024-Flywheel-based inertial training (FIT) has gained popularity as a means to enhance muscle hypertrophy. Other applications, such as aerobic exercise training, remain unexplored. The aim of this study was to determine the cardiorespiratory responses to acute FIT with varying moments of inertia (MOIs). Methods: Overall, 20 (10 M, 10 F) healthy, physically active subjects underwent maximal graded exercise testing and completed 3 bouts of FIT exercise (1 familiarization session and 2 identical data collection sessions). Subjects completed quarter squats (60° peak knee flexion) at a pace of 50 squats·minute-1 until volitional fatigue. Flywheel-based inertial training MOI was increased by 0.005 kg·m2 every 3 minutes until a final workload of 0.020 kg·m2. Heart rate and gas exchange data were collected continuously and averaged over the final 60 s of each stage. Data were analyzed by a linear mixed model. Results: During the final testing session, there was a main effect of MOI to increase heart rate (HR), V̇o2, and RER. Men displayed greater oxygen consumption, but asimilar %V̇o2peak compared with women. We noted a significant inertia × sex interaction where RER tended to be lesser in women at higher MOI. In the final stage of exercise (MOI: 0.020 kg·m2), HR and V̇o2 were approximately 75-80 and 55% of peak, respectively, and RER was approximately 0.95-1.00. Conclusions: FIT quarter squats elicit moderate HR and V̇o2 responses, but near-maximal RER suggests a novel metabolic training stimulus. This exercise may supersede thelactate threshold and may not be sustainable for prolonged times. The physiological and performance effects of training in this manner are unclear.

Effects of different postures on the hemodynamics and cardiovascular autonomic control responses to exercise in postural orthostatic tachycardia syndrome.

To assess the effects of two different body positions on the cardiovascular autonomic profile during a single bout of exercise in patients with postural orthostatic tachycardia syndrome (POTS). Thirteen patients with POTS and thirteen healthy controls (C) participated in the study. ECG, respiration, beat-by-beat arterial pressure and O2 consumption (VO2) were continuously recorded while on a cycle ergometer in supine and upright positions, before and during exercise (6min, 50 Watts). Spectral analysis of RR intervals and systolic arterial pressure (SAP) variability provided indexes of cardiac sympathovagal interaction (LF/HF ratio), cardiac vagal modulation (HFRR, high-frequency component of RR variability, ~ 0.25Hz), sympathetic vasomotor control (LFSAP, low-frequency component of SAP variability, 0.1Hz) and baroreflex sensitivity (BRS, αLF). While supine, patients with POTS showed lower HFRR and αLF, greater heart rate (HR), LF/HF and LFSAP, compared with C, suggesting cardiovascular sympathetic over-activity and reduced BRS. While sitting upright, POTS showed greater HR and reduced HFRR and αLF compared with C. During supine exercise, SAP, HR, LF/HF increased and HFRR and αLF decreased similarly in POTS and C. In POTS, upright sitting exercise was associated with slightly higher , a greater increase in HR whereas LFSAP was lower than in C. Upright exercise was associated with excessive enhancement of HR and a blunted increase of the sympathetic vasomotor control in POTS. Conversely, supine exercise-induced hemodynamic and autonomic changes similar in POTS and C, thus making supine exercise potentially more suitable for physical rehabilitation in POTS.

Acute Effects of Cannabis Inhalation on Arterial Stiffness, Vascular Endothelial Function, and Cardiac Function.

The cardiovascular impact of cannabis use is incompletely understood. Although evidence links chronic use to an increased risk of disease and adverse cardiovascular events, few studies have investigated the acute effects of cannabis inhalation on subclinical dysfunction. Furthermore, it remains unknown how method of inhalation and cannabinoid profile modify risk. While controlling for inhalation method and the effects of either Δ-9-tetrahydrocannabinol (THC) or cannabidiol (CBD), we examined the acute cardiovascular effects of cannabis use on arterial stiffness, vascular endothelial responsiveness, and cardiac function, as markers of cardiovascular impairment. Twenty-two young, healthy, cannabis users were assessed for arterial stiffness via pulse wave velocity, vascular endothelial function via brachial artery flow mediated dilation, and cardiac function via echocardiography, before and after (1) smoking THC-predominant cannabis (S-THC), (2) vaporizing THC-predominant THC (V-THC), and (3) vaporizing cannabidiol-predominant cannabis (V-CBD). S-THC and V-THC increased heart rate (S-THC: ∆17±15 bpm, V-THC: ∆16±16 bpm;both P<0.0001) and mean arterial pressure (S-THC: ∆7±6 mm Hg, V-THC: ∆5±5 mm Hg;both P<0.0001) whereas V-CBDdid not (∆1±4 bpm, ∆3±4 mm Hg;both P>0.05). After inhalation, pulse wave velocity increased (S-THC: ∆0.29±0.75 m/s, V-THC: ∆0.42±0.74 m/s, V-CBD: ∆0.10±0.44 m/s; P=0.002) and diastolic function was reduced ([early/late ratio] S-THC: ∆-0.2±0.53, V-THC: ∆-0.33±58, V-CBD: ∆0.01±66; P=0.03). Differences in heart rate were related to changes in pulse wave velocity (r2=0.2; P=0.0002) and diastolic function (r2=0.26; P<0.0001). Inhalation method did not alter these cannabinoid-dependent responses. THC predominant, but not cannabidiol predominant, cannabis elicits increases in heart rate and blood pressure irrespective of inhalation method, which may increase arterial stiffness and reduce diastolic function. These findings implicate THC as a relevant factor for cannabis-related subclinical cardiovascular dysfunction. URL: https://www.clinicaltrials.gov; Unique identifier: NCT04693884.

Astrocytic inhibition of lateral septal neurons promotes diverse stress responses

Inhibitory neuronal circuits within the lateral septum (LS) play a key role in regulating mood and stress responses. Even though glial cells can modulate these circuits, the impact of astrocytes on LS neural circuits and their functional interactions remains largely unexplored. Here, we demonstrate that astrocytes exhibit increased intracellular Ca²⁺ levels in response to aversive sensory and social stimuli in both male and female mice. This astrocytic Ca²⁺ elevation inhibits neighboring LS neurons by reducing excitatory synaptic transmissions through A1R-mediated signaling in both the dorsal (LSd) and intermediate LS (LSi) and enhancing inhibitory synaptic transmission via A2AR-mediated signaling in the LSi. At the same time, astrocytes reduce inhibitory tone on distant LS neurons. In the LSd, astrocytes promote social avoidance and anxiety, as well as increased heart rate in socially stressed male mice. In contrast, astrocytes in the LSi contribute to elevated heart rate and heightened blood corticosterone levels in unstressed male mice. These results suggest that the dynamic interactions between astrocytes and neurons within the LS modulate physiological and behavioral responses to stressful experiences.