Total Activation Time Research Articles

A case study: High resolution optical mapping of a 19 year old male victim of sudden cardiac death during a marathon

Fifty thousand athletes suffer sudden cardiac death every year due to ventricular fibrillation (VF). Most sudden cardiac deaths of young patients have unexplained origin due to the absence of structural or electrical disease. Purkinje network is essential for a normal heart function, however, its role during electrical pathologies remains unclear. A case study to investigate the electrophysiological properties and the Purkinje network role in a 19 years old male after suffering a fatal sudden cardiac arrest during a marathon event. A coronary-perfused left ventricular preparation was imaged using high resolution optical mapping of epicardial and endocardial surfaces using a voltage-sensitive dye, Di-4-ANEPPS. Activation time, repolarization time and action potential duration were assessed during paced activity through the His bundle and endocardial and epicardial surfaces. Conduction system activation origins were identified as distant endocardial origins during His bundle pacing. Short-coupled S1S2S3S4 pacing was used to determine effective refractory period (ERP). Pacing protocols were repeated in the presence of isoprenaline (ISO) at 100 nM, 500 nM and 1 μM to mimic stress conditions. No changes in total activation time are observed during myocardial pacing cycle lengths of 667ms in control (63ms) and under ISO (up to 64ms). In contrary, His-ventricle delay during conduction system pacing was shorted from 61ms in control to 42ms, 44ms and 16ms under 100 nM, 500 nM and 1 μM of ISO respectively. Under His pacing, local APD gradients are observed near Purkinje-muscle junctions under ISO (from 3ms/mm and 3 ms/mm to 40ms/mm and 41ms/mm). ERP under His pacing was 55ms shorter than endocardial pacing. 82% of the ectopy origins observed have less than 4 mm distance from the PMJs. Repeated focal activations were observed during VF and 76% of them had less than 4 mm distance from PMJs. No structural abnormalities were identified under 9.4 T MRI. Conduction system electrical abnormalities play a role in arrhythmogenicity and maintenance of VF in this patient during sudden cardiac death.

Sinus rhythm endocardial mapping for channels identification in ischemic ventricular tachycardia using a modified electrophysiological triad

Abstract Funding Acknowledgements Type of funding sources: None. Background In a previous study it was demonstrated that an electrophysiological triad was able to identify critical isthmus in atrial flutter (AFL) patients. This triad is based in the Carto® electroanatomical mapping (EAM) version 7, which displays a histogram of the local activation times (LAT) of the tachycardia cycle length (TCL), in addition to the activation and voltage maps. Purpose This study aimed to prospectively assess the ability of a modified electrophysiological triad to identify and localize the ventricular tachycardia’s (VT) channels and entrance zones during sinus rhythm mapping. Methods Prospective analysis of a unicentric registry of individuals who underwent ischemic VT ablation with Carto® EAM, all in sinus rhythm. All patients with non-ischemic etiology, lack of high-density EAM or lack of mapping in any of the left ventricle walls or structures were excluded. Areas of late potentials and possible channels of re-entry were compared to a modified electrophysiological triad constituted by: areas of low-voltage (<0.5mV), a site of deep histogram valley (LAT-Valley) with less than 20% density points relative to the highest density zone and a prolonged LAT-Valley duration that included 10% or more of the total activation time mapped. We also assessed the relationship between the pre-valley bar (the LAT histogram bar immediately before the prolonged LAT-Valley) and the channel entrances. Results A total of 14 patients (14 men, median age 70 IQR 64-78 years) were included. All patients presented with ischemic VT and 86% had a previous inferior myocardial infarction. The median number of collected points were 1733 (IQR 1363─2729). All sinus rhythm maps presented with at least 1 LAT-Valley in the analysed histograms. All arrhythmias were effectively treated after undergoing radiofrequency in the LAT-Valley location, either by blocking the channel entrances or scar homogenization ablation strategy. Also, the pre-valley bar in the histogram marked all the channel entrances in the scar borders. No patient had relapse after a clinical follow up of over 6 months. Conclusion In a prospective analysis, a modified electrophysiological triad was able to identify the scar channels in sinus rhythm in all patients. The pre-valley bar in the histogram disclosed the channel entrances. Further studies are needed to assess the usefulness of this algorithm to simplify catheter ablation and improve clinical outcomes.

C1 THE ROLE OF ATRIAL ELECTRO–MECHANICAL COUPLING AS PREDICTOR OF CATHETER ABLATION EFFICIENCY

Abstract Background Atrial fibrillation (AF) results in electrical and structural remodeling of the atria, and the extent of remodeling has already been found to be associated with higher AF recurrence rate after catheter ablation (CA). Recently, a novel echocardiographic parameter derived from tissue Doppler imaging (TDI), called PA–TDI, has been introduced to assess the total atrial activation time, as a non–invasive surrogate of fibrosis and atrial cardiomyopathy. The aim of the study was to investigate the role of PA–TDI interval as predictor of AF ablation efficacy. Methods Consecutive patients with persistent or paroxysmal symptomatic AF referred to our Center to perform radiofrequency ablation or cryoablation procedures were prospectively enrolled. In these patients, a complete transthoracic echocardiographic examination was performed before and after the ablation procedure, including assessment of the PA–TDI interval. Results From October 2018 to May 2020, 221 consecutive patients (mean age 61 ± 9 years, 74% male, mean BMI 26.5 ± 3.6, mean Ejection Fraction 61 ± 6%) symptomatic for AF, undergoing the procedure ablation (first procedure or re–do) were enrolled. Out of the blanking period, 25% of patients experienced recurrence of arrhythmia during follow–up (mean 16 months). Compared to patients who did not relapse, patients with AF recurrence have a generally longer post–procedural PA–TDI interval (139.6 ± 22.1 msec vs 153.9 ± 33 msec, respectively). In the multivariable analysis only post–procedure PA–TDI and re–do interventions were found to be independent predictors of AF recurrence. A PA–TDI cut–off> 144msec identifies patients at risk of post ablation AF recurrence with sensitivity 58.7% and specificity 73.5% (AUC 0.697). Conclusions The PA–TDI interval is an independent predictor of AF recurrence after catheter ablation. This echocardiographic parameter is easily obtainable, low–cost, reproducible, and accessible even in peripheral centers.

Assessment of Echocardiography-Derived Total Atrial Activation Time at Patients with Type 2 Diabetes Mellitus

Objectives: Atrial fibrillation (AF) is one of the main cardiovascular complications associated with type 2 diabetes mellitus (T2DM). Echocardiography-derived total atrial activation time (PA-TDI duration) which reflects electrical and structural changes to the atria, consistently and accurately predicts new-onset AF. In this study, we aimed to determine the value of PA-TDI duration in T2DM patients. Methods: A total of 40 consecutive patients with T2DM, mean age 51.5 ± 14.3 years, and 40 age and gender-matched healthy volunteers were evaluated. Conventional and tissue Doppler echocardiography were performed. Additionally, we determined the PA-TDI duration as the time interval from the onset of the P-wave in lead II of the ECG to the peak A’-wave on the tissue Doppler tracing. Results: Left atrial (LA) diameter and LA volume index were significantly higher in T2DM patients (3.36 ± 0.5 cm vs.3.10 ± 0.45cm, p=0.037; 30.8 ± 30ml/m2 vs. 29.0 ± 3.4ml/m2, p=0.03 respectively). Mitral A velocity was significantly higher in T2DM patients (69.72 ± 10.16 cm/s vs. 64.75 ± 10.64 cm/s, p=0.029). Doppler E/A ratio was lower in T2DM patients. Tissue Doppler E’/A’ ratio for left ventricular lateral annulus was significantly lower in the diabetic group (1.28±0.33 vs. 1.49±0.40, p=0.024) and E/E’ was significantly higher in the diabetic group (7.33±2.5 vs. 6.45±1.1, p=0.038). PA-TDI duration was significantly higher in the T2DM patients when compared with the controls (134.2±6.0ms vs. 124.3±9.4ms p<0.001). Conclusions: Our results showed that PA-TDI duration is significantly increased in patients with T2DM as compared with healthy volunteers. PA-TDI duration measurement, using transthoracic echocardiography can serve as an easy and non-invasive method of detecting patients with T2DM at risk of atrial fibrillation.

The Impact of Rural Hospital Closures on Emergency Medical Services Transport Times

Purpose: Previous studies have found disparities in emergency medical service (EMS) transports for rural residents including double the average response time and lower patient survival rates when compared with their urban counterparts. Since 2012, the rate of rural hospitals closures has risen alarmingly from previous years. Previous studies have linked the closure of rural hospitals to increased EMS transport and total activation time. However, data and methods used in previous studies have not included facility-level characteristics, which limits the ability to tease out the nuances of each closure. Thus, the purpose of this study is to examine the impact of rural hospital closures on EMS travel time, as well as the characteristics of the closed hospitals. Sample: Data sources for the study came from a state-level EMS database, the CMS Provider of Service files, and state-level hospital data reports. Methods: Geographic information system software was used to geocode hospital locations and generate service areas based on drive times. We identified rural hospitals that closed in Alabama between 2010-2018 and then identified the 911 call data from the state’s EMS database that occurred within close proximity of each of the hospitals of interest, resulting in a sample of 120,802 EMS calls. Findings: We identified five hospital closures within our time period. For one of the five closures, EMS transport time to the emergency department increased by thirteen minutes post-closure. In two of the five closures, transport time increased by five minutes or less. In two instances, however, transport time decreased. Conclusions: Our findings suggest that not all rural hospital closures result in increased EMS transport times as rural patients may have already been routinely transported to alternate hospitals. Additionally, specific characteristics of a hospital pre-closure may be related to changes in EMS travel times that occur post-closure. Keywords: Rural health, emergency medical services, access, hospital closure, travel distance DOI: https://doi.org/10.14574/ojrnhc.v22i1.690

Isotemporal Substitution of Sedentary Behavior by Different Physical Activity Intensities on Pain and Disability of Patients With Chronic Low Back Pain: A Cross-Sectional Study

ObjectiveTo investigate the association of isotemporal substitution modeling (ISM) of time spent in sedentary activities with physical activity in different intensities on pain and disability of patients with chronic low back pain (LBP). DesignObservational and cross-sectional study. Device-measured physical activity levels were assessed using an actigraph. Pain intensity was measured using the 11-point numeric rating scale, and disability was measured using the Roland Morris Disability Questionnaire. The ISM was used to estimate the theoretical substitution association of reallocating time from 1 exposure variable to an equal amount of time in another exposure variable while holding total activity time constant. SettingsOutpatient physical therapy clinic. ParticipantsThis study included data from 358 patients (N=358) with chronic LBP aged between 18 and 60 years. Main Outcome MeasuresPain and disability. ResultsOur results suggest that replacing 60 minutes of sedentary behavior with 60 minutes of vigorous activity in a week is significantly associated with a decrease in pain (β=−1.67; 95% confidence interval [CI], −3.18 to −0.15). Additionally, replacing 60 minutes of light physical activity (β=−1.67; 95% CI, −3.18 to −0.16) or moderate activity (β=−1.67; 95% CI, −3.21 to −0.13) with the same amount of time of vigorous activity per week may also favorable reductions in pain. For the analysis of disability, no significant associations (P>.05) for disability in any of the isotemporal models were found. ConclusionsOur results showed that replacing 60 minutes of sedentary behavior with equal amounts of vigorous activity per week was associated with reductions in pain intensity. Similarly, replacing a light or moderate activities with vigorous activity was also associated with reductions in pain intensity. Finally, no significant associations were observed between time spent in sedentary activities with physical activity in different intensities for disability.

Medico-Social Approach to the Development of a Methodology for Assessing the “Quality of Life” after Cataract Phacoemulsification. Part 1

Purpose. Scientific substantiation of methodological approaches to the development of a “quality of life” (QoL) questionnaire after cataract phacoemulsification (PEC) in patients with visually stressful work (VLT), based on a “medico-social” health model.Methods. The study was carried out on the basis of methodological standards for the development of new tools for assessing symptoms in clinical medicine developed by specialists from the International Center for the Study of Quality of Life (St. Petersburg). This article presents the first stage of development aimed at the formation of a preliminary version of the questionnaire. The initial volume of questions (complaints) of the patient was carried out in the following areas: individual interviews (according to the standard developed methodology) with 50 patients with ZNT; analysis of proven methods for studying QOL in cataracts (“NEI-VFQ”, “Cataract Symptom Scale”, “Catquest-9SF”, etc.); analysis of proven methods for studying QoL in keratorefractive surgery and asthenopic conditions in patients with RNT; analysis of the classification structure of the International Classification of Functioning (ICF) from the standpoint of the development of characteristic “domains”.Results. The data obtained indicate that a total of 35 patient complaints were identified (7 — “visual”; 6 — “professional”; 16 — “functional”; 4 — “household”; 4 — “medical and psychological”). The fundamental difference between the development of the methodology for assessing the patient’s QoL after performing PE is the use of a “social model” of health, which confirms the leading (46 % of all complaints) place for “functional” manifestations of the patient’s subjective status, based on specific “domains” of the ICF. Along with this, the practical application of the basic provisions of the ICF involves scaling the severity of the patient’s complaints in the context of the ratio of the duration of the complaint to the total active time of the patient with a gradation: “Mild problems” (5–24 %); “Moderate problems” (25–49 %); “Severe problems” (50–95 %); “Absolute problems” (96–100 %).Conclusion. The results of the first stage of the development of the patient’s QoL questionnaire after the FEC testify to the compliance with clinical standards in terms of content validity, since the questions, scales and general content reflect the significance for the patient and important parameters from a clinical and functional point of view. A distinctive feature and scientific novelty of the questionnaire is the use of a “social model” of health based on the development of “domains” of the international classification of functioning, as well as optimization of the procedure for scaling patient responses.

Use of Learning Management System Data to Predict Student Success in a Pharmacy Capstone Course

Objective. Learning management system (LMS) data from online classes may provide opportunities to identify students at risk of failure. Previous LMS studies have not addressed the possibility of change in student engagement over time. The purpose of this study was to apply a novel statistical technique, group-based trajectory modeling (GBTM) to LMS data in an online course to identify predictors of successful course completion.Methods. Exploratory GBTM was used to assess the association of LMS activity (total activity time, dates of activity, and pages viewed) and attendance at virtual synchronous learning sessions with examination performance in a capstone disease-management course delivered in the final didactic quarter of a three-year Doctor of Pharmacy program. Groups were assigned based on trajectories of weekly page view counts using structural-equation modeling.Results. Group-based trajectory modeling identified three page view engagement groups (median total page views, n): group 1, high (1,818, n=24): group 2, moderate (1,029, n=74), and group 3, low (441 views, n=35). Group assignment alone was somewhat associated with final grade. Stratification based on consistent virtual synchronous learning session attendance improved predictive accuracy; for example, a top (A or A-) grade was earned by 49.0% and 24.0%, respectively, of group 2 students with and without consistent synchronous engagement.Conclusion. Application of GBTM to LMS data, including information about synchronous engagement, could provide data that allow educators to identify early warning signs that a student may fail a course and target interventions to those at-risk students. The technique should be further tested with alternative LMS data and obtained early in the didactic curriculum, before patterns of engagement are established.

Association Between Physical Activity and Risk of Disabling Dementia in Japan

The associations of daily total physical activity and total moderate to vigorous physical activity (MVPA) with dementia are still unclear. To investigate the association between daily total physical activity and subsequent risk of disabling dementia in large-scale, extended follow-up prospective study. This prospective cohort study used data from questionnaires collected between 2000 and 2003 from 8 areas from the Japan Public Health Center-based Prospective Disabling Dementia Study. Participants included adults aged 50 to 79 years in with available follow-up data on disabling dementia. Data analysis was performed from February 1, 2019, to July 31, 2021. Daily total physical activity, total MVPA, and leisure-time MVPA. The main outcome was incidence of disabling dementia during the dementia ascertainment period between 2006 and 2016, based on the national long-term care insurance system. Risks of dementia in association with daily total physical activity, total MVPA, and leisure time MVPA were calculated using multivariable adjusted hazard ratios (aHRs). Among 43 896 participants (mean [SD] age, 61.0 [7.5] years; 23 659 [53.9%] women), 5010 participants were newly diagnosed with disabling dementia during a mean (SD) of 9.5 (2.8) years in the dementia ascertainment period. In the highest daily total physical activity group, compared with the lowest activity group, risk of dementia was lower in men (aHR, 0.75 [95% CI, 0.66-0.85]; P for trend < .001) and women (aHR, 0.75 [95% CI, 0.67-0.84]; P for trend < .001). Similar inverse associations were observed in men and women for total MVPA (men: aHR, 0.74 [95% CI, 0.65-0.84]; P for trend < .001; women: aHR, 0.74 [95% CI, 0.66-0.83]; P for trend < .001) and leisure-time MVPA (men: aHR, 0.59 [95% CI, 0.53-0.67]; P for trend < .001; women: aHR, 0.70 [95% CI, 0.63-0.78]; P for trend < .001). However, these inverse associations disappeared when participants diagnosed with disabling dementia within 7 years of the starting point were excluded in men (aHR, 0.93 [95%CI, 0.77-1.12]) and within 8 years were excluded in women (aHR, 0.86 [95%CI, 0.71-1.04]). The association remained significant among men in the highest vs lowest group of leisure-time MVPA, after excluding participants diagnosed within the first 9 years (aHR, 0.72 [95% CI, 0.56-0.92]; P for trend = .004). This cohort study examined associations of daily total physical activity and total MVPA with risk of disabling dementia. The findings suggest that a high level of leisure-time MVPA was associated with decreased risk of disabling dementia in men.

On the Electrophysiology and Mapping of Intramural Arrhythmic Focus.

Conventional mapping of focal ventricular arrhythmias relies on unipolar electrogram characteristics and early local activation times. Deep intramural foci are common and associated with high recurrence rates following catheter-based radiofrequency ablation. We assessed the accuracy of unipolar morphological patterns and mapping surface indices to predict the site and depth of ventricular arrhythmogenic focal sources. An experimental beating-heart model used Langendorff-perfused, healthy swine hearts. A custom 56-pole electrode array catheter was positioned on the left ventricle. A plunge needle was placed perpendicular in the center of the grid to simulate arrhythmic foci at variable depths. Unipolar electrograms and local activation times were generated. Simulation models from 2 human hearts were also included with grids positioned simultaneously on the endocardium-epicardium from multiple left ventricular, septal, and outflow tract sites. A unipolar Q or QS complex lacks specificity for superficial arrhythmic foci, as this morphology pattern occupies a large surface area and is the predominant pattern as intramural depth increases without developing a R component. There is progressive displacement from the arrhythmic focus to the surface exit as intramural focus depth increases. A shorter total activation time over the overlying electrode array, larger surface area within initial 20 ms activation, and a dual surface breakout pattern all indicate a deep focus. Displacement from the focal intramural origin to the exit site on the mapping surface could lead to erroneous lesion delivery strategies. Traditional unipolar electrogram features lack specificity to predict the intramural arrhythmic source; however, novel endocardial-epicardial mapping surface indices can be used to determine the depth of arrhythmic foci.

The Effect of the Ultrasonic Irrigant Activation Protocol on the Removal of a Dual-species Biofilm from Artificial Lateral Canals

IntroductionLateral canals are particularly challenging to clean and disinfect. The aim of this study was to compare the removal efficacy of a dual-species biofilm from a lateral canal model by different ultrasonic irrigant activation protocols in vitro. MethodsArtificial root canal models with 270 simulated lateral canals were made of polydimethylsiloxane. A dual-species biofilm (Streptococcus oralis and Actinomyces naeslundi) was grown in vitro in the lateral canals using a constant depth film fermenter. Two percent NaOCl or demineralized water was delivered by a syringe and an open-ended needle for 30 seconds and subsequently activated by an ultrasonic file for a total activation time of 30, 60, or 90 seconds divided in 1 or 3 consecutive activation cycles. In the control groups, the irrigant was allowed to rest for 30, 60, or 90 seconds. The volume of the biofilm in the lateral canal was evaluated before and after the final irrigation protocol by optical coherence tomography. The results were analyzed by 3-way factorial analysis of variance (α = 0.05). ResultsIrrigation with NaOCl rather than demineralized water resulted in more effective biofilm removal from the lateral canal (P < .001). Three cycles of intermittent ultrasonic activation were significantly more effective than no activation (P = .029). The total irrigant contact time did not affect biofilm removal (P = .403). ConclusionsThe type of the irrigant and the ultrasonic activation protocol affected biofilm removal from artificial lateral canals. None of the compared protocols was able to eradicate the biofilm.

A US Time and Motion Pilot Study of Nebulized COPD Therapy in an Inpatient and a Long-Term Care Setting.

IntroductionThere is a lack of quantitative data on healthcare professionals’ (HCPs) time dedicated to nebulized chronic obstructive pulmonary disease (COPD) therapy in inpatient and long-term care (LTC) settings. Using time and motion methodology, we quantified HCP time and opportunity costs (time and materials) associated with nebulized COPD therapy in inpatient and LTC settings and estimated efficiencies of changing to once-daily therapy.MethodsA case report form was built to reflect local nebulization workflow. Primary outcomes were mean active HCP time per predefined task and mean total active HCP time associated with short-acting beta agonist (SABA) and SABA/short-acting muscarinic antagonist (SAMA) combination nebulization processes.ResultsTwenty observations occurred within each setting. Inpatient observations included three SABA and 17 SABA/SAMA (from 18 different patients), and LTC observations included five SABA and 15 SABA/SAMA (from eight different patients). Mean total process time was 16.12 min in the inpatient setting (95% CI 14.48–17.76) and 21.0 min in the LTC setting (95% CI 18.8–23.2), with the actual nebulization comprising over 50% of process time for both. In LTC, CIs suggest a difference by cognitive impairment status: mean 24.1 min (95% CI 21.3–26.9) if cognitively impaired versus 19.0 min (95% CI 16.1–21.8) if not. In the inpatient setting, the estimated process time/admission was 7.8 h; a once-daily nebulized drug would require only 2.3 h. In LTC, the estimated process time was 32.1 h/month; a once-daily nebulized drug would require only 13.7 h/month. Estimated nebulization cost was $243/admission for current versus $72 for once-daily dosing in inpatient, and $1177/month versus $504 in LTC.ConclusionsThe nebulization process for COPD patients in both inpatient and LTC settings consumes considerable HCP time. A switch from SABA or SABA/SAMA to a drug with a once-daily nebulization frequency could generate substantial time savings depending on the setting and site characteristics.

Sedentary behaviour and physical activity are associated with biomarkers of endothelial dysfunction and low-grade inflammation\u2014relevance for (pre)diabetes: The Maastricht Study

Aims/hypothesisBiomarkers of endothelial dysfunction and low-grade inflammation are important in the pathogenesis of CVD and can potentially be modified by physical activity and sedentary behaviour. Effects of physical activity on biomarkers of endothelial dysfunction may be especially prominent in type 2 diabetes.MethodsIn the population-based Maastricht Study (n = 2363, 51.5% male, 28.3% type 2 diabetes, 15.1% prediabetes [defined as impaired glucose tolerance and impaired fasting glucose]), we determined biomarkers of endothelial dysfunction and low-grade inflammation, and combined z scores were calculated. Physical activity and sedentary behaviour were measured by activPAL. Linear regression analyses were used with adjustment for demographic, lifestyle and cardiovascular risk factors.ResultsThe association between total, light, moderate-to-vigorous and vigorous intensity physical activity and sedentary time on the one hand and biomarkers of endothelial dysfunction on the other were generally significant and were consistently stronger in prediabetes and type 2 diabetes as compared with normal glucose metabolism status (p for interaction <0.05). Associations between physical activity and sedentary behaviour on the one hand and low-grade inflammation on the other were also significant and were similar in individuals with and without (pre)diabetes (p for interaction >0.05).Conclusions/interpretationPhysical activity and sedentary behaviour are associated with biomarkers of endothelial dysfunction and low-grade inflammation. For biomarkers of endothelial dysfunction, associations between physical activity and sedentary behaviour were consistently stronger in (pre)diabetes than in normal glucose metabolism. Whether increasing physical activity or decreasing sedentary time can positively influence biomarkers of endothelial dysfunction in individuals with prediabetes and type 2 diabetes requires further study.Graphical abstract

Short-Term Adaptations in Skeletal Muscle Mitochondrial Oxidative Capacity and Metabolic Pathways to Breaking up Sedentary Behaviors in Overweight or Obese Adults.

Breaking up sedentary behavior with short-frequent bouts of physical activity (PA) differentially influences metabolic health compared with the performance of a single-continuous bout of PA matched for total active time. However, the underlying mechanisms are unknown. We compared skeletal muscle mitochondrial respiration (high-resolution respirometry) and molecular adaptations (RNA sequencing) following 4-day exposure to breaks vs. energy-matched single-continuous PA bout in inactive adults with overweight/obesity. Participants (9M/10F, 32.2 ± 6.4 years, 30.3 ± 3.0 kg/m2) completed three 4-day interventions of a randomized cross-over study: SED, sedentary control; MICRO, 5 min brisk walking each hour for 9 h; ONE: 45 min/d continuous brisk walking bout. Fasted muscle biopsies were collected on day 5. Mitochondrial coupling in the presence of lipid-associated substrates was higher after ONE (4.8 ± 2.5) compared to MICRO (3.1 ± 1.1, p = 0.02) and SED (2.3 ± 1.0, p = 0.001). Respiratory rates did not differ across groups with carbohydrate-associated substrates. In pathways associated with muscle contraction transcription signaling, ONE and MICRO similarly enhanced Oxidative Phosphorylation and Sirtuin Signaling expression (p < 0.0001, for both). However, ONE (p < 0.001, for all), but not MICRO, had greater pathway enrichment, including Ca++, mTOR, AMPK, and HIF1α signaling, than SED. Although breaking up sedentary behavior triggered skeletal muscle molecular adaptations favoring oxidative capacity, it did not improve mitochondrial function over the short term.

Validity and Acceptability of Wearable Devices for Monitoring Step-Count and Activity Minutes Among People With Multiple Sclerosis.

Multiple wearable devices that purport to measure physical activity are widely available to consumers. While they may support increases in physical activity among people with multiple sclerosis (MS) by providing feedback on their performance, there is little information about the validity and acceptability of these devices. Providing devices that are perceived as inaccurate and difficult to use may have negative consequences for people with MS, rather than supporting participation in physical activity. The aim of this study was, therefore, to assess the validity and acceptability of commercially available devices for monitoring step-count and activity time among people with MS. Nineteen ambulatory adults with MS [mean (SD) age 52.1 (11.9) years] participated in the study. Step-count was assessed using five commercially available devices (Fitbit Alta, Fitbit Zip, Garmin Vivofit 4, Yamax Digi Walker SW200, and Letscom monitor) and an activPAL3μ while completing nine everyday activities. Step-count was also manually counted. Time in light activity, moderate-to-vigorous activity, and total activity were measured during activities using an Actigraph GT3X accelerometer. Of the 19 participants who completed the validity study, fifteen of these people also wore the five commercially available devices for three consecutive days each, and participated in a semi-structured interview regarding their perception of the acceptability of the monitors. Mean percentage error for step-count ranged from 12.1% for the Yamax SW200 to −112.3% for the Letscom. Mean step-count as manually determined differed to mean step-count measured by the Fitbit Alta (p = 0.002), Garmin vivofit 4 (p < 0.001), Letscom (p < 0.001) and the research standard device, the activPAL3μ (p < 0.001). However, 95% limits of agreement were smallest for the activPAL3μ and largest for the Fitbit Alta. Median percentage error for activity minutes was 52.9% for the Letscom and 100% for the Garmin Vivofit 4 and Fitbit Alta compared to minutes in total activity. Three inductive themes were generated from participant accounts: Interaction with device; The way the device looks and feels; Functionality. In conclusion, commercially available devices demonstrated poor criterion validity when measuring step-count and activity time in people with MS. This negatively affected the acceptability of devices, with perceived inaccuracies causing distrust and frustration. Additional considerations when designing devices for people with MS include an appropriately sized and lit display and ease of attaching and charging devices.

Gender differences in active travel in major cities across the world

There is lack of literature on international comparison of gender differences in the use of active travel modes. We used population-representative travel surveys for 19 major cities across 13 countries and 6 continents, representing a mix of cites from low-and-middle income (n = 8) and high-income countries (n = 11). In all the cities, females are more likely than males to walk and, in most cities, more likely to use public transport. This relationship reverses in cycling, with females often less likely users than males. In high cycling cities, both genders are equally likely to cycle. Active travel to access public transport contributes 30–50% of total active travel time. The gender differences in active travel metrics are age dependent. Among children (< 16 years), these metrics are often equal for girls and boys, while gender disparity increases with age. On average, active travel enables one in every four people in the population to achieve at least 30 min of physical activity in a day, though there is large variation across the cities. In general, females are more likely to achieve this level than males. The results highlight the importance of a gendered approach towards active transport policies. Such an approach necessitates reducing road traffic danger and male violence, as well as overcoming social norms that restrict women from cycling.

Modificação do ambiente para a promoção da atividade física em adolescentes brasileiros: ensaio controlado randomizado em cluster

To assess the effect of modifications of the school environment on physical activity in Brazilian adolescent students. Seven public schools in Duque de Caxias (Brazil) were randomized into control and intervention groups. The intervention group underwent modifications in the school environment (painting of hopscotch and school courts) and the provision of sports equipment (balls, basketball table, soccer goalpost, volleyball nets, and others) to stimulate physical activity. Additionally, footsteps towards the court and materials were painted, and a superhero character called Super Active was introduced. Total physical activity was measured using a validated questionnaire for adolescents. Generalized linear models were used to evaluate the effect of the intervention, adjusted by sex. The sample consisted of 975 adolescents, with a mean age of 11.52 years (standard deviation - SD 1.43), and 56.7% were boys. After the one-month intervention, both groups' total physical activity time increased. The estimated changes from baseline were not different between the intervention and control groups (Δ=102.75 and Δ=99.76, respectively; p=0.52). The painting, supply of equipment and other strategies to encourage physical activity in the school environment did not promote a positive effect on improving physical activity among adolescents. Future research is necessary to evaluate the effect of the intervention in the long-term period, particularly in other population contexts in middle-income countries.

BUNDLE BRANCH BLOCKS SIMULATIONS IN VENTRICULAR MODEL WITH REALISTIC GEOMETRY AND CONDUCTION SYSTEM

The goal of the study was to design a model of cardiac ventricles with realistic geometry that enables simulation of the ventricular activation with normal conduction system functions, as well as with bundle branch blocks. In ventricles, electrical activation propagates from the His bundle to the left and right bundle branches and continues to the fascicles and branching fibers of the Purkinje system. The role of these parts of the conduction system is to lead the activation rapidly and synchronously to the left and right ventricle. The velocity of propagation in the conduction system is several times higher than in the surrounding ventricular myocardium. If the conduction system works normally, QRS duration representing the total activation time of the ventricles lies in the physiological range of about 80 to 120 ms but it is more than 120 ms in the case of bundle branch blocks. In our study, the realistic geometry of the ventricles was constructed on the base of a patient CT scan, defining epicardial and endocardial surfaces. The first part of the conduction system (fast-conducting bundle branches, fascicles in the left ventricle and initial parts of the Purkinje fibers) was modeled as polyline pathways isolated from the surrounding ventricular tissue. The remaining part of the Purkinje system was modeled as an endocardial layer with higher conduction velocity. The propagation of the electrical activation in the ventricular model was modeled using reaction-diffusion (RD) equations, except for the first part of the conduction system, where the activation times were evaluated algebraically with respect to predefined velocity of propagation and estimated distance between the His bundle and particular entry point to the layer with higher conduction velocity. Propagation of activation in cardiac ventricles was numerically solved in Comsol Multiphysics environment. Several configurations of the first part of the conduction system with different number of polyline pathways and entry points were proposed and tested to achieve realistic activation propagation. For the model with 9 starting points, realistic total activation time (TAT) of the whole ventricles of about 108 ms was obtained for the model with normal conduction system, and realistic TAT of 126 ms and 149 ms were obtained for the right and left bundle branch block (RBBB, LBBB), respectively. Very similar TAT was found also for the model with 7 starting points, but unrealistically long TAT was obtained in LBBB simulation for the model with only 5 starting points.

Intervening on exercise and daylong movement for weight loss maintenance in older adults: A randomized, clinical trial.

This study aimed to determine the impact of dietary weight loss (WL) plus aerobic exercise (EX) and a "move more, more often" approach to activity promotion (SitLess; SL) on WL and maintenance. Low-active older adults (age 65-86 years) with obesity were randomized to WL+EX, WL+SL, or WL+EX+SL. Participants received a social-cognitive group-mediated behavioral WL program for 6 months, followed by a 12-month maintenance period. EX participants received guided walking exercise with the goal of walking 150 min/wk. SL attempted to achieve a step goal by moving frequently during the day. The primary outcome was body weight at 18 months, with secondary outcomes including weight regain from 6 to 18 months and objectively assessed physical activity and sedentary behavior at each time point. All groups demonstrated significant WL over 6 months (p < 0.001), with no group differences. Groups that received SL improved total activity time (p ≤ 0.05), and those who received EX improved moderate-to-vigorous activity time (p = 0.003). Over the 12-month follow-up period, those who received WL+EX demonstrated greater weight regain (5.2 kg; 95% CI: 3.5-6.9) relative to WL+SL (2.4 kg; 95% CI: 0.8-4.0). Pairing dietary WL with a recommendation to accumulate physical activity contributed to similar WL and less weight regain compared with traditional aerobic exercise.

AF Inducibility Is Related to Conduction Abnormalities at Bachmann's Bundle.

We investigated whether patterns of activation at Bachmann’s bundle are related to AF inducibility. Epicardial mapping of Bachmann’s bundle during sinus rhythm was performed prior to cardiac surgery (192 electrodes, interelectrode distances: 2 mm). Compared to non-inducible patients (N = 20), patients with inducible AF (N = 34) had longer lines of conduction block (18(2–164) mm vs. 6(2–28) mm, p = 0.048), prolonged total activation time (55(28–143) ms vs. 46(24–73) ms, p = 0.012), multiple wavefronts entering Bachmann’s bundle more frequently (64% vs. 37%, p = 0.046) and more often areas of simultaneous activation (conduction velocity > 1.7 m/s, 45% vs. 16%, p = 0.038). These observations further support a relation between conduction abnormalities at Bachmann’s bundle and AF inducibility. The next step is to examine whether Bachmann’s bundle activation patterns can also be used to identify patients who will develop AF after cardiac surgery during both short- and long-term follow-up.