Minimum HR Research Articles

Analysis of heart rate variability during emergency flight simulator missions in fighter pilots

IntroductionManaging emergency situations in different simulated flight segments can entail a workload that could affect the performance of military pilots. The aim was to analyse the modifications in neurovegetative balance...

P134: Immediate stress responses to music during psychomotor stimulation in 2 study cases with dementia.

Background:The use of music in older people with advanced dementia is possible because perception, sensitivity, emotion, and memory of music may remain intact after other types of memory disappear. Previous literature is controversial about stress biomarkers response to music introduction in therapy routines for people with severe cognitive impairment and neural-behavioural disorders. Particularly, for these patients, it is possible that they feel lower pleasure levels with music-based therapies.Objective:To characterize the immediate physiological effects of listening to music during psychomotor stimulation in an old participant with combined dementia and depression disorder and in a participant with a dementia diagnosis.Methods:Two study cases with dementia diagnosis participated in this study (P1: 84yrs; male Parkinson; FAB=9; P2: 85 yrs; female; Alzheimer; FAB=11; depression diagnosis) and were submitted to psychomotor stimulation (2 sessions). The first 20 min. of each session was dedicated to psychomotor stimulation without music (A), followed by 20 minutes with music (B). Heart rate was monitored (H10 Polar sensor) in a continuous mode. Cortisol levels were collected at the beginning of the session (T0) and then repeated at periods A and B (μg/dL). The range between minimum and maximum HR values (beats per minute- bpm) and mean values for cortisol levels were considered for the stress response analysis.Results:Salivary cortisol levels were higher at T0 for P1 (0.393 vs 0.203). During period A, the P1 slightly decreased their values (↓0,076) and P2 had no changes. After introducing music, both P1 and P2 increased cortisol levels (↑0,085; 0,162↑). For both P1 and P2, a wide range of HR was detected during period B (P1: 13 vs 23 bpm) vs (P2: 15 vs 41 bpm).Conclusion:Immediate responses to the music inclusion in a psychomotor intervention caused an augmented stress response in elderly participants with dementia, especially in P2. In specific, the depression diagnosis in this participant may be associated with a low capacity to handle emotions during new experiences, causing a higher stress response.

Early heart rate fluctuation and outcomes in critically ill patients with sepsis: A retrospective cohort study of the MIMIC-IV database

BackgroundHeart rate (HR) abnormalities are common in critically ill patients, but the significance of HR fluctuation in sepsis remains unclear. We aimed to assess the association of HR fluctuation with intensive care unit (ICU) mortality, hospital mortality, and 28-day mortality in patients with sepsis and identify the cutoff value of HR fluctuation associated with the lowest risk of death. MethodsWe conducted a retrospective cohort study using the medical information mart for the intensive care IV database. HR fluctuation, defined as the difference between maximum and minimum HR within the first 24 h of ICU admission, was analyzed for its association with outcomes using restricted cubic spline and multivariable Cox regression models. ResultsAmong 24,419 eligible patients with sepsis, HR fluctuation showed a J-shaped association with ICU mortality, hospital mortality, and 28-day mortality. The high HR fluctuation group (≥ 35 bpm) had a significantly increased risk of ICU mortality ([hazard ratio, 95% confidence interval] 1.12,1.02–1.22, P = 0.013), hospital mortality (1.10,1.02–1.19, P = 0.013), and 28-day mortality (1.11,1.03–1.20, P = 0.007) compared to the control group (HR fluctuation 25–34 bpm). The low HR fluctuation group (< 25 bpm) showed no significant difference in the risk of mortality compared to the control group. ConclusionsOur large-sample study suggests that early high HR fluctuation is indicative of poor prognosis in critically ill patients with sepsis. Early HR fluctuation may serve as a readily available “high-risk alert system” influencing therapeutic decision-making.

Analysis of Antibiotic Exposure and Development of Acute Graft-vs-Host Disease Following Allogeneic Hematopoietic Cell Transplantation

Certain antibiotic exposures have been associated with increased rates of acute graft-vs-host disease (aGVHD) after allogeneic hematopoietic cell transplantation (allo-HCT). Since antibiotic exposure can both affect and be affected by infections, analyzing time-dependent exposure in the presence of multiple potential confounders, including prior antibiotic exposures, poses specific analytical challenges, necessitating both a large sample size and unique approaches. To identify antibiotics and antibiotic exposure timeframes associated with subsequent aGVHD. This cohort study assessed allo-HCT at a single center from 2010 to 2021. Participants included all patients aged at least 18 years who underwent their first T-replete allo-HCT, with at least 6 months of follow-up. Data were analyzed from August 1 to December 15, 2022. Antibiotics between 7 days before and 30 days after transplant. The primary outcome was grade II to IV aGVHD. The secondary outcome was grade III to IV aGVHD. Data were analyzed using 3 orthogonal methods: conventional Cox proportional hazard regression, marginal structural models, and machine learning. A total of 2023 patients (median [range] age, 55 [18-78] years; 1153 [57%] male) were eligible. Weeks 1 and 2 after HCT were the highest-risk intervals, with multiple antibiotic exposures associated with higher rates of subsequent aGVHD. In particular, exposure to carbapenems during weeks 1 and 2 after allo-HCT was consistently associated with increased risk of aGVHD (minimum hazard ratio [HR] among models, 2.75; 95% CI, 1.77-4.28), as was week 1 after allo-HCT exposure to combinations of penicillins with a β-lactamase inhibitor (minimum HR among models, 6.55; 95% CI, 2.35-18.20). In this cohort study of allo-HCT recipients, antibiotic choices and schedules in the early course of transplantation were associated with aGVHD rates. These findings should be considered in antibiotic stewardship programs.

PO-02-183 ATRIO-VENTRICULAR DISSOCIATION IN PREMATURE VENTRICULAR CONTRACTION WITH DIFFERENT COUPLING INTERVALS

The pathophysiology of Premature ventricular contraction (PVC) induced cardiomyopathy (PVC-CM) remains unclear. AV dissociation (AVD) during PVCs is known as atrial contraction at the time of the PVC. AVD has been implicated as a potential trigger and predictor of PVC-CM, especially early AVD since it results in an increase in LA pressure due to mitral valve closure. The goal of this study was to assess AVD during short- and long-coupled PVCs, and its correlation with the development of PVC-CM. Thirty-one canines underwent implantation of 1) a modified pacemaker to reproduce RV apical PVCs and 2) a telemetry device with a bipole implanted in the LA appendage and RV to record local electrograms and assess AVD during PVCs. Animals were randomized to short-coupled (200ms, n=14), long-coupled (330ms, n=8) bigeminal PVCs, or no PVCs (sham, n=11). AVD was categorized as absent (no P wave during QT interval), early (P wave present between QRS and the peak of the T wave of PVC), or late AVD (P wave between peak and end of T wave of PVC). AVD for four 1-minute segments (6 AM, 12 PM, 6 PM, and 12 AM) for 24 hours and LV ejection fraction were assessed after weeks 1, 4, and 12 of bigeminal PVCs. Ponemah software was used for HR analysis to calculate the minimum, maximum, and average HR and PVC burden. Overall AVD was similar between short- and long-coupled PVCs throughout the 12 weeks (Panel A). Short-coupled PVCs had 35% and 21% of early and late AVD, respectively and no AVD in 44%. Long-coupled PVCs had 50% and 13% of early and late AVD, respectively, without AVD in 37% (Panel B). The early AVD was significantly higher in long-coupled PVCs compared to short-coupled PVCs (50% vs. 35%, Two-Way ANOVA P<0.001), while late AVD was higher in short-coupled PVCs compared to long-coupled PVCs (22% vs. 13%, Two-Way ANOVA, p=0.018) (Panel A &C). Neither short nor long-coupled PVCs showed a significant correlation between AVD and reduction in LVEF at 12 weeks (r=0.09, r=0.06 with p=0.5, p=0.8, respectively). The short- and long-coupled PVCs had increased HR relative to the sham groups (121 vs. 105 vs. 83, Two-Way ANOVA p<0.001). Moreover, HR was significantly higher in short-coupled PVCs than in Long-coupled PVCs (121 vs. 105, Two-Way ANOVA p< 0.001). Early AVD is more pronounced in long-coupled PVCs. AVD does not predict the development of PVC-CM regardless of PVC coupling interval, suggesting that AVD does not play a role in the pathophysiology of PVC-CM.

PE-454609-2 MARFAN SYNDROME AND VENTRICULAR ARRHYTHMIAS IN PEDIATRICS: MITRAL ANNULAR DISJUNCTION, MITRAL VALVE PROLAPSE OR BOTH – WHICH IS THE REAL CULPRIT?

Mitral Annular Disjunction (MAD) and Mitral Valve Prolapse (MVP) have been associated with sudden death and ventricular arrhythmias (VA) in adults with connective tissue disease (CTD). While rare, there has been a case report of sudden cardiac death due to VA in a pediatric Marfan patient. However, risk factors have not been well described in this population. Our aim is to assess the association of MAD and MVP with VA in pediatric patients with Marfan syndrome. A retrospective single center cohort study was conducted and included all patients (≤ 21yrs) with clinical (based on Ghent’s criteria) and/or genetic diagnosis of Marfan syndrome. Clinical data including ambulatory cardiac monitoring and echocardiograms were reviewed prior to any mitral valve intervention, if applicable. 32 patients (38% female) with Marfan syndrome (66% with fibrillin 1 mutation) were included. The mean age was 13.5 ± 4.5 yrs. The results revealed MAD in 8 pts (25%), isolated MVP in 5 pts (16%) and bileaflet MVP in 14 pts (44%). Anterior MVP was seen in 16 pts (50%) and posterior MVP in 17 pts (53%). The mean MAD distance was 6.7 ± 2.3 mm. There was normal LV systolic function in 31 pts (97%). The median duration of cardiac monitoring was 58 hrs (IQR: 33-191). 26 pts (81%) had isolated ventricular ectopy (VE), 27 pts (84%) had complex VE (defined as couplets, triplets or NSVT), 4 pts (12.5%) had NSVT and none had sustained VT. The median VE per hour was 0.2 (IQR: 0-1). There was no R on T seen but short coupled VE (<350ms) was seen in 46% of isolated, 46% of couplets and 67% of triplets. Monomorphic ectopy was seen in 28% of isolated and 100% of couplets, triplets and NSVT. There were 5 total episodes of NSVT (Figure 1) with a mean HR of 159 ± 29 bpm, an absolute minimum HR of 94 bpm and maximum HR of 222 bpm. MAD was not associated with the presence of, or complexity in, ventricular arrhythmias. Anterior MVP was only associated with complexity in VE (p= 0.043), but posterior MVP and bileaflet MVP were not. MAD was associated with MVP (anterior, posterior and bileaflet; p= 0.026). There was a high incidence of complex VE and NSVT in this cohort of pediatric Marfan patients despite low overall ectopy burden. Anterior MVP but not MAD was associated with complexity in VE. However, MAD was associated with MVP. Larger studies are needed to better characterize MAD, including distance and circumferential extent, and MVP and their association with VA in pediatric patients with CTD.

Identification of Bradycardia Following Remdesivir Administration Through the US Food and Drug Administration American College of Medical Toxicology COVID-19 Toxic Pharmacovigilance Project

The rapid spread and mortality associated with COVID-19 emphasized a need for surveillance system development to identify adverse events (AEs) to emerging therapeutics. Bradycardia is a remdesivir infusion-associated AE listed in the US Food and Drug Administration-approved prescribing information. To evaluate the magnitude and duration of bradycardic events following remdesivir administration. A multicenter cohort study of patients with recorded heart rate less than 60 beats per minute within 24 hours after administration of a remdesivir dose was conducted between November 23, 2020, and October 31, 2021. Participants included patients hospitalized with COVID-19 at 15 medical centers across the US. Patients excluded had AEs unrelated to bradycardia, AEs in addition to bradycardia, or first onset of bradycardia after 5 remdesivir doses. Remdesivir administration. Linear mixed-effect models for the minimum HR before starting remdesivir and within 24 hours of each dose included doses as fixed effects. Baseline covariates were age (≥65 years vs <65 years), sex (male vs female), cardiovascular disease history (yes vs no), and concomitant use of bradycardia-associated medications. The interactions between variables and doses were considered fixed-effects covariates to adjust models. A total of 188 patients were included in the primary analysis and 181 in the secondary analysis. The cohort included 108 men (57.4%); 75 individuals (39.9%) were non-Hispanic White and mean (SD) age was 61.3 (15.4) years. Minimum HR after doses 1 to 5 was lower than before remdesivir. Mean minimum HR was lowest after dose 4, decreasing by -15.2 beats per minute (95% CI, -17.4 to -13.1; P < .001) compared with before remdesivir administration. Mean (SD) minimum HR was 55.6 (10.2) beats per minute across all 5 doses. Of 181 patients included in time-to-event analysis, 91 had their first episode of bradycardia within 23.4 hours (95% CI, 20.1-31.5 hours) and 91 had their lowest HR within 60.7 hours (95% CI, 54.0-68.3 hours). Median time to first bradycardia after starting remdesivir was shorter for patients aged 65 years or older vs those younger than 65 years (18.7 hours; 95% CI, 16.8-23.7 hours vs 31.5 hours; 95% CI, 22.7-39.3 hours; P = .04). Median time to lowest HR was shorter for men vs women (54.2 hours; 95% CI, 47.3-62.0 hours vs 71.0 hours; 95% CI, 59.5-79.6 hours; P = .02). In this cohort study, bradycardia occurred during remdesivir infusion and persisted. Given the widespread use of remdesivir, practitioners should be aware of this safety signal.

Sex differences in estimates of cardiac autonomic function using heart rate variability: effects of dietary capsaicin.

Heart rate variability (HRV) estimates the autonomic nervous system (ANS) influence on the heart and appears sex-specific. Sensory afferents exhibit sex-specificity; although, it is unknown if Capsaicin, an agonist for transient receptor potential vanilloid channel-1 (TRPV1), alters cardiac ANS activity in a sex-dependent manner, which could be important given the predictive nature of HRV on risk of developing hypertension. Thus, we explored if there was sex-specificity in the effect of capsaicin on estimated cardiac ANS activity. HRV was measured in 38 young males (M: n = 25) and females (F: n = 13), in a blinded-crossover design, after acute ingestion of placebo or capsaicin. Resting HR, RR-interval, root-mean-square of successive differences (RMSSD), natural log-transformed RMSSD (LnRMSSD), standard deviation of n-n intervals (SDNN), number of pairs of successive n-n intervals differing by > 50ms (NN50), and percent NN50 (PNN50) were obtained using standard techniques. Significant sex differences were observed in mean HR (M: 59 ± 9.3 vs. F: 65 ± 12 beats/min, p = 0.036, η2 = 0.098), minimum HR (M: 47 ± 8.3 vs. F: 56 ± 12 beats/min, p = 0.014, η2 = 0.124), and NN50 (M: 177 ± 143 vs. F: 29 ± 17, p < 0.001, η2 = 0.249). There was a significant interaction of sex*treatment (p = 0.02, η2 = 0.027) for RMSSD, where males increased (78 ± 55 vs. 91 ± 64ms), and females decreased (105 ± 83 vs. 76 ± 43ms), placebo vs. capsaicin. This controlled study recapitulates sex differences in HR and HRV, but revealed a sexual dimorphism in the parasympathetic response to capsaicin, perhaps due to differing TRPV1-afferent sensitivity, highlighting a potential mechanism for differential regulation of hemodynamics, and CVD risk, and should beconsidered in future studies.

Medical nutrition therapy and clinical outcomes in critically ill adults: a European multinational, prospective observational cohort study (EuroPN)

BackgroundMedical nutrition therapy may be associated with clinical outcomes in critically ill patients with prolonged intensive care unit (ICU) stay. We wanted to assess nutrition practices in European intensive care units (ICU) and their importance for clinical outcomes.MethodsProspective multinational cohort study in patients staying in ICU ≥ 5 days with outcome recorded until day 90. Macronutrient intake from enteral and parenteral nutrition and non-nutritional sources during the first 15 days after ICU admission was compared with targets recommended by ESPEN guidelines. We modeled associations between three categories of daily calorie and protein intake (low: < 10 kcal/kg, < 0.8 g/kg; moderate: 10–20 kcal/kg, 0.8–1.2 g/kg, high: > 20 kcal/kg; > 1.2 g/kg) and the time-varying hazard rates of 90-day mortality or successful weaning from invasive mechanical ventilation (IMV).ResultsA total of 1172 patients with median [Q1;Q3] APACHE II score of 18.5 [13.0;26.0] were included, and 24% died within 90 days. Median length of ICU stay was 10.0 [7.0;16.0] days, and 74% of patients could be weaned from invasive mechanical ventilation. Patients reached on average 83% [59;107] and 65% [41;91] of ESPEN calorie and protein recommended targets, respectively. Whereas specific reasons for ICU admission (especially respiratory diseases requiring IMV) were associated with higher intakes (estimate 2.43 [95% CI: 1.60;3.25] for calorie intake, 0.14 [0.09;0.20] for protein intake), a lack of nutrition on the preceding day was associated with lower calorie and protein intakes (− 2.74 [− 3.28; − 2.21] and − 0.12 [− 0.15; − 0.09], respectively). Compared to a lower intake, a daily moderate intake was associated with higher probability of successful weaning (for calories: maximum HR 4.59 [95% CI: 1.5;14.09] on day 12; for protein: maximum HR 2.60 [1.09;6.23] on day 12), and with a lower hazard of death (for calories only: minimum HR 0.15, [0.05;0.39] on day 19). There was no evidence that a high calorie or protein intake was associated with further outcome improvements.ConclusionsCalorie intake was mainly provided according to the targets recommended by the active ESPEN guideline, but protein intake was lower. In patients staying in ICU ≥ 5 days, early moderate daily calorie and protein intakes were associated with improved clinical outcomes.Trial registrationNCT04143503, registered on October 25, 2019.Graphical abstract

Sex Differences in Estimates of Cardiac Autonomic Function Using Time Domain based Method of Heart Rate Variability: Effects of Oral Capsaicin

Heart rate variability (HRV) estimates autonomic nervous system (ANS) influence on the heart and is sex‐specific. Sensory afferents exhibit sex‐specificity; although, there is a paucity of data on the potential effects of Capsaicin, an agonist for transient receptor potential vanilloid channel‐1 (TRPV1), on cardiac ANS activity and if the effect is sex‐dependent. Given the predictive nature of HRV on risk of developing hypertension, understanding the sex differences in factors governing HRV is paramount.PURPOSETherefore, this study sought to determine the sex‐specificity in the effect of capsaicin on cardiac autonomic function estimated through HRV. It was hypothesized that females would have lower HRV than the age‐matched males and that capsaicin could attenuate these sex differences.METHODSHRV was measured in 38 young males (M: n=25) and females (F: n=13), in a blinded crossover design, after acute ingestion of placebo or capsaicin capsules. Resting measurements of HR, RR interval, root mean square of successive differences (RMSSD), natural log‐transformed RMSSD (LnRMSSD), standard deviation of n‐n intervals (SDNN), number of pairs of successive n‐n intervals that differ by more than 50 msec (NN50), and percent NN50 to total n‐n intervals (PNN50) were obtained using standard techniques.RESULTSUnder placebo, males had significantly lower minimum HR (M: 49±9.7 vs. F: 58±16 beats/min, p=0.038, d=‐0.738) and significantly higher NN50 (M: 141±118 vs. F: 33±23, p=0.003, d=‐0.129) than females. There was a main effect of sex on HR (M: 59±9.3 vs. F: 65±12 beats/min, p=0.036, η2=0.098), minimum HR (M: 47±8.3 vs. F: 56±12 beats/min, p=0.014, η2=0.124), and NN50 (M: 177±143 vs. F: 29±17, p&lt;0.001, η2=0.249). There was a significant interaction of sex and treatment (p=0.02, η2=0.027) for RMSSD, where males increased (Placebo: 78±55 vs. Capsaicin: 91±64 ms), and females decreased (Placebo: 105±83 vs. Capsaicin 76±43 ms).CONCLUSIONThis study recapitulates previously documented sex differences in HR and HRV. Acute ingestion of capsaicin increased RMSSD in men, but decreased RMSSD in women, suggesting a sexual dimorphism in parasympathetic response, perhaps due to differences in TRPV1‐sensitive afferents or sensitivity. The physiological ramifications of these findings, specifically in the regulation of blood pressure and ultimately cardiovascular disease risk remain to be explored, especially in the transition to menopause in women.

Vasovagal syncope as a specific side effect of rTMS: A frontal-vagal dose-finding study

Abstract In the treatment of depression using repetitive Transcranial Magnetic Stimulation (rTMS), the intensity of stimulation is established based on the motor threshold (MT). Neuro-Cardiac-Guided TMS (NCG-TMS) is a newly developed method to optimize and individualize target location and to determine the intensity of treatment. In this method, the frontal threshold is established by evaluating the effect of stimulation of the DLPFC on heart rate variability and may be a better proxy for frontal excitability thresholds. In our pilot study (n=10), aimed at further optimizing NCG-TMS, one of the subjects experienced a syncope during the stimulation. In this case 10Hz stimulation (ITI 11 sec) was applied to the left Beam-F3 site in increasing intensities. Intensity was started at a low intensity and was increased in 5% points of machine output in 7 consequent steps, where the 5th intensity corresponded to 100% of the MT. ECG was measured simultaneously using a Brainquiry PET EEG device and BioExplorer software. ECG data were analyzed offline using Kubios software. During the assessment the resting heart rate dropped from 80BPM to 60BPM and HRV increased. The first cardiac effects already appeared at a stimulation intensity of 45% machine output, which represented 75% of the individual MT. The subject experienced feelings of dizziness and lightheadedness during the stimulation. The HR-data of the subject’s Fitbit collected over the prior month demonstrated an average HR of 67.6 BPM and a minimum HR of 65 BPM. This suggests that the DLPFC-rTMS specifically induced a HR-deceleration below the subject’s minimum HR. Presumably, the syncope was caused by overstimulation relative to the frontal excitability threshold. This may suggest that vasovagal syncope is a specific side effect of applying rTMS over the DLPFC. To avoid unwanted side effects of over stimulation, future studies should focus on frontal thresholding when applying rTMS. Keywords: Frontal Thresholding, Syncope, NCG-TMS, rTMS

Recurrent Symptomatic Supraventricular Tachycardia In A Collegiate Volleyball Player

ACSM Case Report SubmissionCalan Sowa, MD HISTORY: A 21-year-old collegiate women’s volleyball player with a past medical history of supraventricular tachycardia (SVT) ablated in July of 2020 presented to the training room after developing shortness of breath and palpitations while participating in volleyball practice. Her symptoms arose spontaneously, and she experienced no chest pain or dizziness, endorsed no recent fevers or chills and had no recent sick contacts. She had no history of illicit substance use and had been otherwise feeling well. PHYSICAL EXAMINATION: Examination in the training room revealed regular tachycardia at a rate of approximately 200 beats per minute. Blood pressure was within normal limits. The patient exhibited no dyspnea and bilateral lungs were clear to auscultation. Neurologic exam was within normal limits. EKG was not available in the training room and therefore the patient was instructed to report to the Emergency Room for further evaluation. DIFFERENTIAL DIAGNOSIS: 1. Supraventricular tachycardia2. Ventricular tachycardia3. Viral myocarditis TESTS AND RESULTS: Troponin I: normalBasic Metabolic Panel: normalEKG: Normal sinus rhythm with HR 56 bpm48-Hour Holter Monitor: -Predominant rhythm: SVT with normal AV conduction-Average HR: 75 bpm, Minimum HR 44 bpm, Maximum HR 194 bpm-Ectopy: Occasional PACs without ventricular ectopy-Dysrhythmias: Supraventricular tachycardia (SVT); 399 beats at 215 bpm-Symptoms: Palpitations and shortness of breath reported once at which time the rhythm was sinus with a rate of 53 bpm FINAL WORKING DIAGNOSIS: Recurrent SVT TREATMENT AND OUTCOMES: 48-hour Holter monitoring confirmed an episode of recurrent SVT lasting for approximately twenty seconds that occurred during participation in volleyball practice. The patient was referred to cardiology and ultimately elected to follow up with her home cardiologist in Virginia. She is awaiting evaluation and resulting medical/procedural management and return-to-play instruction.

Cardiac arrhythmias six months following traumatic spinal cord injury

Objective To investigate the incidence of cardiac arrhythmias at six months following traumatic spinal cord injury (SCI) and to compare the prevalence of arrhythmias between participants with cervical and thoracic SCI. Design A prospective observational study using continuous twenty-four-hour Holter monitoring. Setting Inpatient rehabilitation unit of a university research hospital and patient home setting. Participants Fifty-five participants with acute traumatic SCI were prospectively included. For each participant, the SCI was characterized according to the International Standards for Neurological Classification of SCI by the neurological level and severity according to the American Spinal Injury Association Impairment Scale. Outcome measures Comparisons between demographic characteristics and arrhythmogenic occurrences as early as possible after SCI (4 ± 2 days) followed by 1, 2, 3, 4 weeks and 6 month time points of Holter monitoring. Results Bradycardia (heart rate [HR] <50 bpm) was present in 29% and 33% of the participants with cervical (C1–C8) and thoracic (T1–T12) SCI six months after SCI, respectively. The differences in episodes of bradycardia between the two groups were not significant (P < 0.54). The mean maximum HR increased significantly from 4 weeks to 6 months post-SCI (P < 0.001), however mean minimum and maximum HR were not significantly different between the groups at the six-month time point. There were no differences in many arrhythmias between recording periods or between groups at six months. Conclusions At the six-month timepoint following traumatic SCI, there were no significant differences in occurrences of arrhythmias between participants with cervical and thoracic SCI compared to the findings observed in the first month following SCI.

Clinical analysis of cardiac autonomic ganglion plexus ablation for bradyarrhythmia: Research protocol for an intervention study.

This study aimed to explore the safety and effectiveness of selective cardiac autonomic ganglion plexus (GP) ablation on patients with bradyarrhythmia. The heart is controlled by its own intrinsic and central autonomic nerves. Increased cardiac vagal tone leads to sinus node dysfunction and atrioventricular conduction disorders, resulting in bradyarrhythmia. Pacemaker implantation can relieve the symptoms of arrhythmia caused by bradycardia, but it is not easy for patients to accept a pacemaker implantation as a form of treatment. Therefore, more and more attention has been paid to cardiac vagus nerve ablation. In this study, 20 patients who met the inclusion criteria of GP ablation in the First Affiliated Hospital of Xinjiang Medical University from November 2019 to June 2020 were enrolled. Biochemical and other related examinations along with electrophysiological examinations were conducted before ablation, and then cardiac GP ablation was performed. The patients were followed up 3 times at 3, 6, and 12 months after the operation. The minimum HR and mean HR were significantly increased after treatment with cardiac autonomic GP ablation (p<0.01). Moreover, the SDNN (Standard deviation of Normal-to-Normal Intervals) and RMSSD (Root mean square successive differences between successive R-R intervals) was significantly decreased after treatment with cardiac autonomic ganglion plexus ablation for 6 months and 12 months (p<0.01). Cardiac GP ablation is relatively simple and easy to implement in units that have performed radiofrequency ablation for bradyarrhythmias. This procedure can be performed without any new equipment. Some patients with bradycardia may not have a permanent pacemaker implantation and may go in for additional treatment options.

Effect of Physiotherapy Treatment in the Autonomic Activation and Pain Perception in Male Patients with Non-Specific Subacute Low Back Pain.

Introduction: Physiotherapy treatment is a common intervention for low back pain (LBP) patients. These interventions have been related to physiological effects in the central nervous system. Thus, the aim of this study was to analyze the effect of physiotherapy treatment in patients with LBP in the autonomic nervous system activation and subjective pain perception of patients. Methods: A total of 30 male subjects diagnosed with non-specific subacute LBP received a 50 min session consisting of (a) a manual therapy based on joint mobilization and soft tissues techniques in the lumbo-pelvic area, (b) a stretching program, and (c) motor control exercises of the core muscles. The autonomic modification of participants was assessed prior to and after the physiotherapy treatment. Results: Heart rate variability (HRV) analysis reported a significant increase in average RR (p = 0.001), RMSSD (p = 0.008), LRMSSD (p = 0.001), SDNN (p = 0.005), and PNN50 (p = 0.024) after the session. Frequency-domain measures showed a significant increase in LF (p = 0.030) and HF (p = 0.014), and a decrease in LF/HF ratio (p = 0.046). A significant decrease was found in minimum HR values (p = 0.001) and average HR (p = 0.001). Moreover, maximal HR decreased its value from 116.7 ± 26.1 to 113.7 ± 40.8 after intervention. In addition, subjective pain perception (VAS scores) was significantly lower (p = 0.001) in the post-session assessment. Conclusions: Physiotherapy treatment produced an increase in parasympathetic nervous system activation and a decrease in subjective pain perception in non-specific subacute LBP patients.

Dewetting temperatures of prefrozen and grafted layers in solid ultrathin films viewed as melt-memory effects

Undercooled phase exists behind glass phase with superheated medium-range order between Tg and Tn+ > Tm. The ordered volume fraction stays equal to the percolation threshold F ≅ 0.15 of broken bonds up to Tn+. The difference ΔTg between Tg(bulk) of films with thickness (h > h0) and Tg(h) of ultrathin films of thickness (h < h0) is a linear function of (h-ho). Dense layer with minimum thickness hr is grafted against substrate by isothermal annealing, rinsed to reduce film thickness below hr/F, and finally dewetted at Tg. Similar thickness prepared and annealed near Tm and heated above Tm contains residual crystallized layer dewetting at Tn+. The prefrozen layer reproduces the glassy grafted layer in a crystallized state up to Tn+. Melting heat and melting temperature Tm are linear functions of h for h < h0. Prefrozen layers are due to melt-memories leading to new scenarios of crystallization.

Efficacy of Rest Redistribution During Squats: Considerations for Strength and Sex.

Boffey, D, Clark, NW, and Fukuda, DH. Efficacy of rest redistribution during squats: Considerations for strength and sex. J Strength Cond Res 35(3): 586-595, 2021-This study examined the kinematic, perceptual, and heart rate responses to rest redistribution (RR) and traditional sets (TS) during the barbell back squat for men and women possessing a wide range of strength levels. Forty-five resistance-trained subjects (30 men and 15 women) performed 40 repetitions of the barbell squat with 65% 1RM load with TS (4 × 10 repetitions, 3-minute rest) or RR (10 × 4 repetitions, 1-minute rest), in a randomized order on days separated by ≥72 hours. The significance was set at p ≤ 0.05 for all statistical analyses. The mean velocity (MV) maintenance was significantly higher for RR compared with TS (87.70 ± 4.50% vs. 84.07 ± 4.48%, respectively; p < 0.01, d = 0.35). Rating of perceived exertion (active muscles) was significantly lower for RR compared with TS (5.38 ± 1.42 vs. 6.08 ± 1.43, respectively; p = 0.02, d = -0.35). Rating of perceived exertion (overall) was also significantly lower for RR compared with TS (5.60 ± 1.40 vs. 6.48 ± 1.49, respectively; p = 0.02, d = -0.37). The relative strength ratio (relative strength ratio; squat 1RM: body mass) was significantly correlated with the difference in MV maintenance between RR and TS (r = -0.34, p = 0.02). No sex-based differences (p > 0.05) were found for any dependent variables. Rest redistribution produced significantly higher mean HR (143.25 ± 21.11 vs. 135.05 ± 20.74, p < 0.01) and minimum HR (102.77 ± 19.58 vs. 95.97 ± 22.17, p < 0.01). Subjects were better able to maintain velocity with RR compared with TS, while experiencing less perceived effort. Rest redistribution can be recommended for both men and women, but very strong individuals may not improve their velocity maintenance with RR to the same extent as less strong individuals.

The Role of Heart Rate Variability and Fragmented QRS for Determination of Subclinical Cardiac Involvement in Beta-Thalassemia Major

Background: Iron accumulation leads to increased susceptibility to cardiovascular diseases in thalassemia major (TM) patients. Depressed heart rate variability (HRV) and development of arrhythmia are among the manifestations of subclinical cardiac involvement in TM cases. Determination of subclinical cardiac involvement is essential for preventive measures. Thus, we aimed to evaluate the best method for identification of subclinical cardiac dysfunction in TM cases. Materials and Methods: In this prospective study, 45 TM and 45 non-TM cases, who were referred for cardiac evaluation, were enrolled. Exclusion criteria included non-sinus rhythm and overt cardiac disease. TM cases underwent cardiac MRI, electrocardiography (ECG), and Holter monitoring. TM cases were divided into two groups of normal versus iron overload with a cardiac T2* of more or less than 20 ms, respectively. The non-TM cases underwent only ECG and Holter monitoring. Results: We observed no significant difference regarding HRV between normal versus iron overload TM and non-TM cases. Higher rates of premature atrial complex, low limb voltage, low atrial rhythm, as well as minimum and average HR with lower QRS duration and PR interval were detected in TM versus non-TM cases (p value <0.05). Conclusions: We observed a higher prevalence of low limb voltage and low atrial rhythm in TM cases versus non-TM cases. Indeed, the role of fragmented QRS (fQRS) for subclinical detection of cardiac disease in TM cases is still so controversial and needs more evaluation. Application of HRV and fQRS in this regard may need to be performed at the right time point after initiation of blood transfusion, but this needs to be determined.

Changes in Anesthetic and Postoperative Sedation-Analgesia Practice Associated With Early Extubation Following Infant Cardiac Surgery: Experience From the Pediatric Heart Network Collaborative Learning Study.

The Pediatric Heart Network sponsored the multicenter Collaborative Learning Study that implemented a clinical practice guideline to facilitate early extubation in infants after repair of isolated coarctation of the aorta and tetralogy of Fallot. We sought to compare the anesthetic practice in the operating room and sedation-analgesia management in the ICU before and after the implementation of the guideline that resulted in early extubation. Secondary analysis of data from a multicenter study from January 2013 to April 2015. Predefined variables of anesthetic, sedative, and analgesia exposure were compared before and after guideline implementation. Propensity score weighted logistic regression analysis was used to determine the independent effect of intraoperative dexmedetomidine administration on early extubation. Five children's hospitals. A total of 240 study subjects who underwent repair of coarctation of the aorta or tetralogy of Fallot (119 preguideline implementation and 121 postguideline implementation). None. Clinical practice guideline implementation was accompanied by a decrease in the median total intraoperative dose of opioids (49.7 vs 24.0 µg/kg of fentanyl equivalents, p < 0.001) and benzodiazepines (1.0 vs 0.4 mg/kg of midazolam equivalents, p < 0.001), but no change in median volatile anesthetic agent exposure (1.3 vs 1.5 minimum alveolar concentration hr, p = 0.25). Intraoperative dexmedetomidine administration was associated with early extubation (odds ratio 2.5, 95% CI, 1.02-5.99, p = 0.04) when adjusted for other covariates. In the ICU, more patients received dexmedetomidine (43% vs 75%), but concomitant benzodiazepine exposure decreased in both the frequency (66% vs 57%, p < 0.001) and cumulative median dose (0.5 vs 0.3 mg/kg of ME, p = 0.003) postguideline implementation. The implementation of an early extubation clinical practice guideline resulted in a reduction in the dose of opioids and benzodiazepines without a change in volatile anesthetic agent used in the operating room. Intraoperative dexmedetomidine administration was independently associated with early extubation. The total benzodiazepine exposure decreased in the early postoperative period.

Adult clonidine overdose: prolonged bradycardia and central nervous system depression, but not severe toxicity

Context: There are limited reports of adult clonidine overdose. We aimed to describe the clinical effects and treatment of clonidine overdose in adults.Methods: This was a retrospective review of a prospective cohort of poisoned patients who took clonidine overdoses (>200 μg). Demographic information, clinical effects, treatment, complications (central nervous system and cardiovascular effects) and length of stay (LOS) were extracted from a clinical database or medical records.Results: From 133 admissions for clonidine poisoning (1988–2015), no medical record was available in 14 and 11 took staggered ingestions. Of 108 acute clonidine overdoses (median age 27 years; 14–65 years; 68 females), 40 were clonidine alone ingestions and 68 were clonidine with co-ingestants. Median dose taken was 2100 μg (interquartile range [IQR]: 400–15,000 μg). Median LOS was 21h (IQR: 14–35 h) and there were no deaths. Glasgow coma score [GCS] <15 occurred in 73/108 (68%), and more patients taking co-ingestants (8/68; 12%) had coma (GCS <9) compared to clonidine alone (2/40; 5%). Miosis occurred in 31/108 (29%) cases. Median minimum HR was 48 bpm (IQR: 40–57 bpm), similar between clonidine alone and co-ingestant overdoses. There was a significant association between dose and minimum HR for clonidine alone overdoses (p = 0.02). 82/108 (76%) had bradycardia, median onset 2.5 h post-ingestion (IQR: 1.7–5.5 h) and median duration 20 h (2.5–83 h), similar for clonidine alone and co-ingestant overdoses. There were no arrhythmias. Three patients ingesting 8000–12,000 μg developed early hypertension. Median minimum systolic BP was 96 mmHg (IQR: 90–105 mmHg) and hypotension occurred in 26/108 (24%). 12/108 patients were intubated, but only 2 were clonidine alone cases. Treatments included activated charcoal (24), atropine (8) and naloxone (23). The median total naloxone dose was 2 mg (IQR: 1.2–2.4 mg), but only one patient given naloxone was documented to respond with partial improvement in GCS.Discussion: Clonidine causes persistent but not life-threatening clinical effects. Most patients develop mild central nervous system depression and bradycardia. Naloxone was not associated with improved outcomes.