Heart Rate Interval Research Articles

Comparison of 6-lead smartphone ECG and 12-lead ECG in athletes and a genetic heart disease population

ABSTRACT Background Smartphone electrocardiograms (iECGs) are an innovative method of capturing transient arrhythmias which are occasionally experienced by athletes. This study aimed to assess the accuracy of a 6-lead iECG compared with 12-lead ECG in athletes and those with known genetic heart disease (positive controls). Research design and methods Each participant had a resting 12-lead ECG (supine) and a 30 second 6-lead iECG (seated) taken within 2 hours. Manual measurements of heart rate, QTc and PR intervals, and QRS duration were completed using digital calipers. Bland-Altman analysis was used to assess the quantitative agreement of measurements. Results The 6-lead readings for heart rate were faster than the 12-lead in athletes (n = 233) and positive controls (n = 49). All other measurements were shorter in the 6-lead. QTc mean difference was smaller in the positive controls (4.7 ± 26.0 ms) than in athletes (12.5 ± 25.0 ms). The largest difference was in PR intervals, both in athletes (12.8 ± 17.7 ms) and positive controls (7.6 ± 18.9 ms). QRS duration had the smallest mean difference (0.6 ± 9.0 ms in athletes, 1.0 ± 12.7 ms in positive controls). Conclusions The 6-lead readings had reasonable agreement with the 12-lead ECG. A 6-lead iECG is a reasonable option to opportunistically capture arrhythmias that may occur infrequently, but should not replace a 12-lead if available.

A156: The Effects of School-Based Concurrent Training on Body Composition and Cardiorespiratory Fitness in Obese Children

Objective: High-intensity interval training (HIIT) is a highly effective form of exercise for the obese population. Concurrent training (CT) is also an effective intervention. Simultaneous training is often in the form of strength combined with aerobic training. Considering the high efficiency of HIIT, this study considered combining HIIT with aerobic training and HIIT with resistance training respectively to form two simultaneous training programs to observe its effects on body composition and cardiorespiratory fitness in children with obesity. Methods: Thirty children with obesity [age: (10.1 ± 0.7) years, BMI: (55.0 ± 6.1) kg/m2] were recruited from a primary school and randomly assigned into two concurrent training groups (CT1, CT2) and a control group (CG). CT1 group performed sprint interval training [3 sets × 10 bouts of 15 seconds sprint at 90% maximal heart rate (HRmax) interval by 15 seconds’ rest, 3 minutes rest between each set], followed by 10 minutes of aerobic ladder climbing [10 bouts of 12 ladders at 60~70% HRmax with 15 seconds’ rest, 3 minutes rest between each set]. The CT2 group performed the same sprint interval training as CT1, followed by 10 minutes of core-strength training (plank 60 s × 1, supine leg raise 10 times × 2, bicycle crunches 10 s × 2, seated scissor kicks 20 s × 1, sit-ups 20 times × 1, with 15 s rest and 1-minute rest between sets). Body composition and cardiorespiratory fitness were measured pre- and post-intervention and analyzed using ANOVA tests and t-tests with SPSS 25.0. Results: The paired sample t-test found that body weight, BMI, body fat percentage, body fat, and visceral adipose tissue area were significantly improved (t-values: 5.014, 7.271, 6.736, 2.883, 6.217, P < 0.05). The 20 m-SRT and VO2max increased (t-values: -10.301, -15.95, P < 0.05). Among them, the indices in the CT2 group showed significant changes (t-values: 6.265, 7.901, 5.821, 10.256, -3.097, P < 0.05). The 20 m-SRT and VO2max increased (t-values: -8.583, -11.375, P < 0.05). ANOVA analysis of changes in CT1 and CT2 pre- and post-intervention found that body weight, BMI, visceral fat, 20 m-SRT, and VO2max improvements in the CT1 group were significantly better than those in the CT2 group (F-values: 6.468, 7.652, 48.384, 7.821, 20.101, and 27.655; all P < 0.05). Conclusion: The CT training of HIIT combined with ladder training can achieve a more efficient weight loss effect and improve cardiorespiratory fitness. HIIT combined with aerobic exercise can be an efficient exercise prescription for children with obesity.

Electrocardiographic Changes in Second and Third Trimester in Bangladesh: A Comparative Study

Background: During pregnancy, there are notable changes in cardiovascular function to meet the increasing needs of the developing baby. The objective of this study was to compare ECG in pregnant women during their second and third trimesters with a control group of non-pregnant women in Bangladesh. This study aims to offer valuable insights into the cardiovascular changes that happen during pregnancy. This study's findings are important for maternal health research and clinical practice in Bangladesh and beyond. Objective: The purpose of this study is to analyze and compare the ECG variations in women during the second and third trimesters of pregnancy. Methods: The study took place in the gynecology Department at CMH Saidpur, Bangladesh. This study was conducted from March 2023 to August 2023. During this period, 75 pregnant patients in their 2nd trimester and 75 patients in their 3rd trimester were chosen as cases from antenatal outdoor, while 75 non-pregnant women of the same age were selected as the control group. We use the purposive sampling method. Results: During pregnancy, there were notable changes in BMI, heart rate, and PR interval. BMI decreased in the second trimester and increased in the third trimester.22.67% were nulliparous and 77.33% were multiparous in 2nd trimester. In the third trimester, 26.67% were nulliparous and 73.33% multiparous. So, no significant difference in parity. Heart rate increased in both trimesters, while the PR interval shortened in both trimesters. No significant changes were observed in the durations of the QRS complex or QT interval. In our study, the QTc interval displayed a significant rise. ST depression, which may suggest decreased blood flow, was exclusively seen in pregnant women, particularly in the third trimester. Conclusion: We found no significant changes in age, but BMI, heart rate, and PR interval were significantly different from the control group throughout pregnancy. No significant QRS complex or QT interval duration changes were identified. The QTc interval rose. ST depression, more prominent in the third trimester, only affected pregnant women. As shown by ST depression, pregnancy may change cardiac function, electrical activity, and ischemia.

Predicting atrial fibrillation from ECG characteristics

Abstract Background/Introduction Atrial fibrillation (AF) is the most common cardiac arrythmia, and demographic shifts in age continues to increase the prevalence of atrial fibrillation on a global scale. With manifestations of short and intermittent duration, identifying and diagnosing AF often proves to be a challenge. As a consequence, patients who develop AF are at risk of experiencing stroke and other cardiac diseases such as heart failure (HF) before appropriate treatment is initialized. Despite the potential benefits of early AF detection, risk profiling based on electrocardiographic (ECG) findings is currently lacking. Several smaller studies have identified ECG characteristics associated with increased risk of AF, but these characteristics have not been individually evaluated in large-scale nationwide cohorts, and no evidence exists on the additive effect of these ECG characteristics. Purpose We aimed to evaluate the risk of new-onset AF, HF, and stroke according to five ECG characteristics previously linked to AF, in order to identify potential predictors of AF. Methods We used national registers and the Danish Nationwide ECG Cohort to include patients with ECG measurements taken between 2010 and 2022. Patients were grouped according to how many of the following ECG characteristics were present in their baseline ECG: Elevated heart rate (>80), prolonged PR-interval (≥196 ms for women and ≥204 ms for men), biphasic P-waves (positive and negative amplitude within same p-wave), abnormal P terminal force (≥ 6000 mV×ms), and prolonged P-wave duration(≥120 ms). Patients were followed for 2 years to evaluate the risk of atrial fibrillation, heart failure (HF), and stroke, according to baseline ECG characteristics. Results We included 1,505,474 patients of whom 594,702 had exactly one ECG characteristic, 197,367 had two characteristics, 44,983 had three characteristics, 6,390 had four characteristics, and 451 had all five characteristics on their baseline ECG. The risk of developing AF or HF increased with the number of ECG characteristics present on the baseline ECG. Patients with two ECG characteristics had a 2-fold increased risk of AF or HF compared to patients with no ECG characteristics (HR: 2.11 95%CI: 2.05-2.16). Patients with two or more ECG characteristics present on their baseline ECG exceeded a 5% 2-year absolute risk of developing either AF or HF. Among patients with only one ECG characteristic on their baseline ECG, elevated heart rate and prolonged PR interval were the factors most associated with an increased risk of AF compared to patients with none of the ECG characteristics on their baseline ECG. Conclusions The absolute and relative risk of atrial fibrillation, heart failure, and stroke increased with the number of ECG characteristics present on the baseline ECG. We suggest that the ECG characteristics evaluated in this study could be used in screening scenarios for atrial fibrillation to identify high risk patients.Absolute and relative 2-year risksRisk acc. to specific ECG characteristic

The importance of heart rate on left ventricular global longitudinal strain in echocardiography: novel insights facilitated by automated deep learning methods

Abstract Background Heart rate (HR) is assumed to influence echocardiographic measurements. Consequently, HR needs to be considered for accurate assessment of cardiac function. Despite left ventricular global longitudinal strain (LV GLS) being recognised as a valuable measure of cardiac function, its normal reference ranges remain confined to patients within a limited range of resting HR. So far, time-consuming manual analyses and high measurement variability have precluded comprehensive assessment of the interplay between HR and LV GLS. Using fully automated GLS measurements provided by novel deep learning (DL) methods, it is now possible to evaluate changes in LV GLS across a wide range of HR. Purpose To improve echocardiographic assessments across a wide range of HR intervals, we aimed to study the influence of controlled HR variations on LV GLS using programmable pacemakers and fully automated DL measurements. Methods Participants with sinus node dysfunction and implanted programmable pacemakers were enrolled. Echocardiographic acquisitions were obtained at baseline HR and during stepwise increments by 10 beats/min, targeting a range from 50 to 140 beats/min. Recordings of cine-loops including 10 cardiac cycles were obtained for the four-chamber, two-chamber, and apical long axis view. LV GLS was measured for all cycles using a fully automated DL method developed by our group, and presented as mean of the three standard apical views for all patients at each HR level. A linear mixed model was used for construction of an overall trendline based on the estimated fixed effects across all 50 patients, stating patient number as the random effect. The correlation between HR and LV GLS was evaluated by a likelihood ratio test. Results Fifty patients were included, 52% females, mean age 68 years (27 to 88 years). All patients had preserved atrioventricular conduction. Resting HR ranged from 50 to 87 beats/min (mean 64 beats/min). At baseline echocardiographic acquisition, most participants were within normal ranges for LV volumes, systolic and diastolic function. A total of about 13,000 cardiac cycles were automatically analysed by the DL method. The overall trend demonstrated a linear relation between increasing HR and decreasing absolute LV GLS (Figure 1). Across HR increments from 50 to 140 beats/min, there was a 32% (22%–42%) reduction in absolute LV GLS, declining from -17.1% to -11.7%. The strong correlation between changes in HR and LV GLS was further supported by a highly significant likelihood ratio test (p-value <0.001). Conclusions There was a reduction of absolute LV GLS with increasing HR. These findings emphasize the importance of integrating HR considerations into clinical echocardiography practice. Moreover, the results highlight that DL methods can unlock substantially richer insights from individual patient data, offering a new pathway towards more personalized and precise cardiac diagnostics.Figure 1

Comparison of Standard and Prone-Position Electrocardiograms in COVID-19 Patients With Pulmonary Complications: Correlations and Implications.

Previous research highlighted variability in electrocardiogram (ECG) readings across patient positions, particularly in the context of COVID-19 patients with pulmonary complications requiring prone positioning as part of the treatment. This study aimed to elucidate the effects of prone positioning on ECG parameters and explore its association with the severity of COVID-19. A prospective cohort study involved 60 patients diagnosed with COVID-19 and presenting pulmonary complications. ECGs were recorded in both supine and prone positions, and analyzed for various parameters including heart rate, QRS axis, and QTc interval. Clinical severity was assessed using APACHE II scores and SpO2/FiO2 ratios. Prone positioning led to an increase in heart rate (mean difference: 2.100, 95% CI: 0.471-3.729, p = 0.012), with minor shifts in the QRS axis. Heart rate and QRS axis demonstrated strong positive correlations between positions, with Pearson's correlation coefficients of 0.927 and 0.894, respectively. The study also found a significant association between prolonged QTc intervals in the prone position and elevated APACHE II scores, with a relative risk of 10.75 (95% CI: 1.82-63.64, p = 0.008). The prone positioning caused minor yet significant changes in heart rate and QRS axis. The correlation of prolonged QTc intervals in the prone position with higher APACHE II scores suggests the prognostic relevance of prone ECG in COVID-19 patients. However, further research is needed to fully understand the clinical implications and mechanisms of these findings.

Comparing the effects of three local anaesthetic agents on cardiac conduction system - A randomised study.

This study aimed to compare the effects of three local anaesthetic (LA) agents, namely bupivacaine, levobupivacaine, and ropivacaine, on the cardiac conduction system as assessed by corrected QT (QTc) and P wave dispersion (PWD) intervals in lower limb orthopaedic surgeries and to find the most suitable LA agent that can be used for a long duration. The study included 75 patients with American Society of Anesthesiologists physical status I and II of either gender in the age group of 18-65 years undergoing elective lower limb orthopaedic surgeries under epidural anaesthesia. These were allocated to groups B (bupivacaine), L (levobupivacaine), and R (ropivacaine). We observed blood pressure, heart rate, respiratory rate, PWD, and QTc intervals from baseline value through Holter monitoring, pain assessment by visual analogue scale, and demand and total volume of LA consumed by patient-controlled analgesia devices. The repeated measures of ANOVA were carried out to find the effect of time and time-to-group interaction among the groups across the periods. On intergroup comparison of QTc and PWD, no significant difference among groups was observed, but on intragroup analysis, a statistically significant increase in QTc and PWD from baseline was observed for each of groups B, L, and R at all time intervals. However, the mean increase in QTc and PWD recorded for Group B was higher than in groups L and R. Bupivacaine has the maximal tendency to prolong QTc and PWD. All three agents showed comparable haemodynamic effects and time to onset of sensory and motor blockade.

Is the development of arrhythmia predictable in rheumatoid arthritis?

This study aimed to determine whether there is a difference in the electrocardiography (ECG) measurements of healthy controls and rheumatoid arthritis (RA) patients and to predict whether they can be used to determine the risk of arrhythmia in patients. The prospective study included 50 cardiac asymptomatic RA patients (38 males, 12 females; mean age: 46.8±9.1 years; range, 18 to 60 years) who met the 2010 American College of Rheumatology/European Alliance of Associations for Rheumatology RA criteria and 50 healthy volunteers (34 males, 16 females; mean age: 43.4±10.4 years; range, 18 to 60 years) as a control group between June 1, 2022, and August 31, 2022. Disease activity of the patients was calculated with the Disase Activity Score (DAS28). Heart rate, minimum and maximum QT intervals, QT dispersion, minimum and maximum P waves, P wave dispersion (Pd), minimum and maximum Tp-e intervals, Tp-e dispersion, minimum and maximum corrected QT (QTc) intervals, QTc dispersion, and the Tp-e/QTc ratio in ECGs were calculated. The mean disease duration of the RA group was 9.09±5.74 years. The mean C-reactive protein level was 9.83±8.29, the mean erythrocyte sedimentation rate was 26.12±16.28 mm/h, and the mean DAS28 was 3.03±0.37. There was a statistically significant increase in the maximum P wave, Pd, maximum QT, QT dispersion, maximum QTc, QTc dispersion, maximum Tp-e, Tp-e dispersion, and Tp-e/QTc dispersion parameters in the RA group compared to the control group, while there was a significant decrease in the minimum P wave, minimum QT, and minimum QTc parameters. In our study, the Pd, QTc dispersion, Tp-e dispersion, and Tp-e/QTc dispersion values of our patients, which indicate the risk of atrial and ventricular arrhythmia, were found to be significantly higher. This finding suggests that our patients had an increased risk of cardiac morbidity and mortality. Arrhythmias are the likely source of the increase in sudden cardiac death in RA, and these new indicators measured on ECG can be used as standardized cardiovascular morbidity and mortality indicators in the future.

Characteristics of electrocardiogram in fulminant myocarditis

Objective: To investugate the unique electrocardiogram (ECG) characteristics of fulminant myocarditis (FM) patients and provide important clues for the diagnosis of FM. Methods: This was a retrospective study. Patients diagnosed with acute myocarditis at Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology from February 2017 to April 2022 were enrolled and divided into fulminant myocarditis group (FM) and non-fulminant myocarditis group (NFM) according to clinical diagnosis. A total of 246 healthy people who underwent physical examination in the Health examination Center of Tongji Hospital at the same period were selected as the control group. The clinical data and ECG characteristics of the above 3 groups were analyzed and compared. Logistic regression model was used to analyze the influence of ECG parameters on left ventricular ejection fraction in FM patients. Receiver operating curves were constructed to evaluate the predictive value of different ECG parameters for FM. Results: A total of 180 patients were included in this study (FM group: n=123; NFM group: n=57), with an age of (35.0±16.2) years and 106 males (58.89%). Compared with NFM group, ECG was significantly abnormal in FM group, with a higher incidence of sinus tachycardia, ventricular tachycardia or ventricular fibrillation, escape rhythm, right bundle branch block, third degree atrioventricular block, ST-segment elevation, low voltage, prolonged QTc interval, and widened QRS wave in the FM group (all P<0.05). The ECG parameters showed that the amplitude of the full lead QRS wave in FM group was lower than that in NFM group (P<0.01). The average heart rate and QTc interval of FM group were significantly higher than those of NFM and control groups (all P<0.05). Although ST-segment elevation had a higher incidence in the FM group, ECG parameters showed that except for leads Ⅲ and aVF, the ST segment levels in all leads in the FM group were lower than those in the control group (all P<0.05). There was a statistically significant difference in some ST segment changes between FM and NFM groups, while there was no statistical difference between the NFM and control groups. Multivariate regression analysis showed that widened QRS wave and increased heart rate were the influencing factors for left ventricular systolic dysfunction in FM patients (OR=16.914, 95%CI: 1.367-209.224, P=0.028; OR=1.026, 95%CI: 1.010-1.042, P=0.001). Receiver operating curve analysis showed that heart rate>86.90 beat/min, QTc>431.50 ms, and RV5+SV1<1.72 mV had certain predictive value for FM diagnosis. Conclusions: FM patients displayed marked and severe ECG abnormalities, and characteristic changes in ECG can provide important first clues for the diagnosis of FM.

Acute, dose-response effects of guayusa leaf extract on mood, cognitive and motor-cognitive performance, and blood pressure, heart rate, and ventricular repolarization.

We conducted a randomized, double-blind, placebo-controlled crossover trial in young adults to examine the dose-dependent (600 mg versus 1200 mg), acute effects of consumption of an Ilex guayusa tea extract (GLE) on mood, cognitive and motor-cognitive performance, as well as its acute cardiovascular effects. Twenty-five adults (mean ± SD, age = 28 ± 7 y; 9 M/16 F) completed familiarization and then three randomly ordered experimental visits where they consumed either 600 mg (GLE600) or 1200 mg (GLE1200) GLE or placebo (PLA). Following supplement consumption, participants completed a mood state survey, assessments of perceived jitteriness, energy, and focus, and neurocognitive and motor-cognitive testing. Blood pressure (BP), heart rate, and QT interval length were determined before and after supplementation. GLE600 significantly improved total mood disturbance (mean ± SE difference = -6.9 ± 2.6 au, p = 0.034), fatigue-inertia (-2.84 ± 0.89 au, p = 0.008), perceived energy (+13.00 ± 4.49 au; p = 0.02), motor speed (+4.52 ± 1.42 au, p = 0.008), and psychomotor speed (+7.20 ± 2.16 au, p = 0.005) relative to PLA. GLE1200 also improved psychomotor speed (+5.08 ± 2.16 ms, p = 0.045) and uniquely increased motor-cognitive performance as reflected by a decrease in reaction time (-0.106 ± 0.04 ms, p = 0.026) during a neurocognitive hop test. The effect of GLE on jitteriness was both dose- and sex-dependent. Jitteriness increased with increasing GLE dose in women only (p < 0.001). Both GLE600 and GLE1200 similarly increased systolic and diastolic BP by 4-5 mmHg (p ≤ 0.022). Neither GLE600 nor GLE1200 acutely influenced QTc length (p = 0.31). The goal of GLE supplementation should be considered when selecting a dosing strategy. Lower dosages of GLE (e.g. 600 mg) appear to optimize cognitive and mood-related outcomes while limiting side-effects such as jitteriness in women, and higher dosages may be necessary (e.g. 1200 mg) to promote improvements in motor-cognitive performance.

Generation of cardiomyocytes from stem cells cultured on nanofibrous scaffold: Experimental approach for attenuation of myocardial infarction

The current study was constructed to fabricate polyamide based nanofibrous scaffolds (NS) and to define the most promising one for the generation of cardiomyocytes from adipose tissue derived mesenchymal stem cells (ADMSCs). This purpose was extended to assess the potentiality of the generated cardiomyocytes in relieving myocardial infarction (MI) in rats. Production and characterization of NSs were carried out. ADMSCs were cultured on NS and induced to differentiate into cardiomyocytes by specific growth factors. Molecular analysis for myocyte-specific enhancer factor 2 C (MEF2C) and alpha sarcomeric actin (α-SCA) expression was done to confirm the differentiation of ADMSCs into cardiomyocytes for further transplantation into MI induced rats. Implantation of cells in MI afflicted rats boosted heart rate, ST height and PR interval and lessened P duration, RR, QTc and QRS intervals. Also, this type of medication minified serum lactate dehydrogenase (LDH) and creatine kinase-MB (CK-MB) enzymes activity as well as serum and cardiac troponin T (Tn-T) levels and upraised serum and cardiac α-SCA and cardiac connexin 43 (CX 43) levels. Microscopic feature of cardiac tissue sections of rats in the treated groups revealed great renovation in the cardiac microarchitecture. Conclusively, this attempt gains insight into a realistic strategy for recovery of MI through systemic employment of in vitro generated cardiomyocytes.

Consumer wearable devices for evaluation of heart rate control using digoxin versus beta-blockers: the RATE-AF randomized trial

Consumer-grade wearable technology has the potential to support clinical research and patient management. Here, we report results from the RATE-AF trial wearables study, which was designed to compare heart rate in older, multimorbid patients with permanent atrial fibrillation and heart failure who were randomized to treatment with either digoxin or beta-blockers. Heart rate (n = 143,379,796) and physical activity (n = 23,704,307) intervals were obtained from 53 participants (mean age 75.6 years (s.d. 8.4), 40% women) using a wrist-worn wearable linked to a smartphone for 20 weeks. Heart rates in participants treated with digoxin versus beta-blockers were not significantly different (regression coefficient 1.22 (95% confidence interval (CI) −2.82 to 5.27; P = 0.55); adjusted 0.66 (95% CI −3.45 to 4.77; P = 0.75)). No difference in heart rate was observed between the two groups of patients after accounting for physical activity (P = 0.74) or patients with high activity levels (≥30,000 steps per week; P = 0.97). Using a convolutional neural network designed to account for missing data, we found that wearable device data could predict New York Heart Association functional class 5 months after baseline assessment similarly to standard clinical measures of electrocardiographic heart rate and 6-minute walk test (F1 score 0.56 (95% CI 0.41 to 0.70) versus 0.55 (95% CI 0.41 to 0.68); P = 0.88 for comparison). The results of this study indicate that digoxin and beta-blockers have equivalent effects on heart rate in atrial fibrillation at rest and on exertion, and suggest that dynamic monitoring of individuals with arrhythmia using wearable technology could be an alternative to in-person assessment. ClinicalTrials.gov identifier: NCT02391337.

Comparison of electrocardiogram and blood pressure recording methods in non-rodent toxicology studies: A retrospective analysis

Our study retrospectively examines 51 non-rodent general toxicology studies conducted over the past 8 years to ascertain the influence of recording methodologies on baseline cardiovascular (CV) parameters and statistical sensitivity. Specifically, our work aims to evaluate the frequency of cardiovascular parameter recording categorized by therapeutic modality and study type, to assess the variability in these parameters based on measurement techniques, and to determine the sample sizes needed for detecting relevant changes in heart rate (HR), blood pressure (BP), and QTc interval in non-human primate (NHP) studies.Results indicate that electrocardiogram (ECG) measurements in dogs and NHP were recorded in 63% of studies, combined with BP recording in 18% of studies, while BP was never recorded alone. Trend analysis reveals a decline in the utilisation of restraint-based methods for ECG measurements post-2017, to the benefit of telemetry-based recordings, particularly Jacketed External Telemetry (JET). There was a marked difference in baseline values, with restraint-based methods showing significantly higher HR and QTc values compared to JET, likely linked to animal stress.Further analysis suggests an unrealistic and unethical sample size requirement in NHP studies for detecting biologically meaningful CV parameter changes using restraint-based methods, while JET methods necessitate significantly smaller sample sizes.This retrospective study indicates a notable shift from snapshots short-duration, restraint-based methods towards telemetry approaches over the recent years, especially with an increased usage of implanted telemetry. The transition contributes to potential consensus within industry or regulatory frameworks for optimal practices in assessing ECG, HR, and BP in general toxicology studies.

Sex differences of 12 lead electrocardiographic findings of the rugby football league athlete

Cardiac electrical adaptations occur within athlete populations. Sex-related variations in the normal athlete electrocardiogram (ECG) have been observed, with males exhibiting increased QRS and PR intervals, while females have demonstrated increased QTc intervals in university-level athletes. Male athletes also maintain greater weekly training hours compared to female athletes, which is associated with increased ECG changes. The presence of these differences within Rugby Football League (RFL) athletes is unknown. This study aimed to investigate any sex-related variations in the 12-lead ECG in RFL athletes. Fifty nine RFL athletes (32 males [age = 25 ± 5 years] and 27 females [age = 24 ± 5 years]) were included in the study. One female was excluded with inferior T wave inversion and was referred for further investigation. The 12-lead ECG was collected as part of the athlete’s pre-season cardiac screening alongside completion of a health questionnaire, assessment of height and weight and brachial artery pressure. Continuous variables (i.e. heart rate, PR interval, QRS interval etc.), were analysed using an independent t-test or a Mann-Whitney U test as appropriate. For assessment of nominal data (i.e. incidence of early repolarisation and junctional rhythm etc.) a chi-squared test or Fishers exact test were used. A Spearman’s correlation coefficient was used to determine any association between training hours and ECG findings. Ethics approval was obtained from Liverpool John Moores University Ethics Committee. Height (183 ± 5 vs. 169 ± 5 cm, P &lt;0.001), weight (95 ± 11 vs. 77 ± 11 kg, P &lt;0.001) and weekly training hours (18 ± 5 vs. 12 ± 5 hrs, P = 0.001) were higher in male athletes. PR interval (156 ± 34 vs. 142 ± 19 ms, P = 0.002), QRS duration (98 ± 9 vs. 88 ± 7 ms, P &lt;0.001) and incidence of early repolarisation (47% vs. 11%, P = 0.004) were greater in males. Heart rate (57 ± 9 vs. 63 ± 11 bpm P = 0.016) and QTc interval (391 ± 20 vs. 414 ± 17 ms, P &lt;0.001) were greater in females. There was a significant negative correlation between weekly training hours and QTc interval (rs = −0.355, P = 0.009) only. In conclusion, there are significant sex-related ECG differences within RFL athletes that partially mirror previous research. These findings emphasise the importance of considering sex-related variations, during cardiac screening on RFL athletes and enhance our understanding of the normal RFL athlete ECG.

Handgrip strength test for the diagnosis of long QT syndrome

Long QT syndrome (LQTS) assessment is based on the QT/ÖRR equation (the so-called Bazett's formula) and calculating the corrected QT (QTc). However, this formula reliably estimates the QT interval in the heart rate range (HR) of 60-90 bpm, which makes it difficult to diagnose LQTS in patients with sinus bradycardia, typical of this disease.Aim. To improve the LQTS diagnosis in patients with sinus bradycardia using the handgrip strength test.Material and methods. A total of 188 patients aged 5-53 years (16 [13;17]) were examined: group I — 40 healthy children aged 9-17 years (14 [12;16]); group II — 98 athletes with sinus bradycardia &lt;60 bpm aged 16 [16;17] years; group III — 50 patients with LQTS aged 5-53 years (12 [10;16]). The handgrip strength test consisted of regular rhythmic compression of a hand expander with a resistance of 20 kg until the heart rate increased &gt;60 bpm. The patients had an electrocardiogram recorded twice before and after the handgrip test. Heart rate, QT and QTc intervals were analyzed.Results. In all groups, after using the expander, there was a significant increase in heart rate, QT interval shortening and QTc interval prolongation. QTc interval prolongation after the handgrip test &gt;460 ms was a highly sensitive marker of LQTS (Se 96%, Sp 60%).Conclusion. Proposed handgrip test for sinus bradycardia makes it possible to increase heart rate, which ensures a more correct use of the Bazett's formula for assessing the corrected QT interval (QTc). QTc interval prolongation over 460 ms after the handgrip test is a highly sensitive additional marker for identifying patients with LQTS.

Исследование соотношений между показателями ритмической активности сердца человека

The purpose of this article was to determine the correlations between the electrical and mechanical parameters of the rhythmic activity of the heart (HRA) in humans taking into account age and the effect of functional loads. Materials and methods. The research involved 146 people of both sexes aged between two hours after birth and 92 years, who were examined using functional tests that differed depending on the age of the subjects. Electrocardiogram (ECG) and heart rate (HR) parameters were recorded in the standard lead II using the Poly-Spectrum ECG system (Neurosoft, Ivanovo). Results. Correlations between HRA parameters can be traced from the first hours of post-embryogenesis throughout the rest of a person’s life. The data obtained indicate a dependence of HRA on the age and on the effect of functional tests, as well as confirm the proposition that there is an inverse relationship between HR dynamics and the dynamics of myocardial electrical parameters. ECG recordings at birth indicate that the correlations between ECG and HR are formed as early as in the prenatal period. Their correlations in people aged between 70 and 92 years indicate a strain associated with the wear and tear of the body’s functional systems. HR and ECG parameters are based on the electrical properties of the myocardium, which are significantly affected by the autonomic nervous system (ANS). A linear range of correlations between HR and ECG intervals was compiled. The maximum values of the duration of the PP interval and TP segment correspond to the minimum HR values. With an increase in HR from 40 to 80 beats/min, the duration of the TP segment decreases twoto three-fold. With HR reaching 120 ± 5 beats/min, the duration of the TP segment drops to zero. Since the increase in HR continues further in response to functional tests, it is obvious that at this stage the process is provided only by the neurohumoral components of the ANS. Due to the maximum variability of the duration of the TP segment, its most important role in the organization of HRA is emphasized.

Vectorcardiography signs of a failing Fontan: Heart rate, PR interval, RtQRSvm, QRSvm and SPQRS-T angle as noninvasive markers of late Fontan complications and mortality

BackgroundLimited data exists on interpreting vectorcardiography (VCG) parameters in the Fontan population. ObjectiveThe purpose of this study was to demonstrate the associations between ECG/VCG parameters and Fontan failure (FF). Methods/results107 patients with a Fontan operation after 1990 and without significant ventricular pacing were included. FF and Fontan survival (FS) groups were compared. The average follow-up after Fontan operation was 11.8 years ±7.1 years. 14 patients had FF (13.1%) which was defined as having protein-losing-enteropathy (1.9%), plastic bronchitis (2.8%), Fontan takedown (1.9%), heart transplant (5.6%), NYHA class III-IV (2.8%) or death (0.9%). A 12‑lead ECG at last follow up or prior to FF was assessed for heart rate, PR interval, QRS duration, Qtc and left/right sided precordial measures (P-wave, QRS and T-wave vector magnitudes, spatial P-R and QRS-T angles). Transthoracic echocardiogram evaluated atrioventricular valve regurgitation and ventricular dysfunction at FF or last follow up. A cox multivariate regression analysis adjusted for LV dominance, ventricular dysfunction, HR, PR, QTc, Pvm, QRSvm, SPQRST-angle, RtPvm, RtQRSvm and RtTvm. Ventricular dysfunction, increased heart rate and prolonged PR interval were significantly associated to FF at the multivariate analysis. ROC analysis and Kaplan-meier analysis revealed an increased total mortality associated with a heart rate > 93 bpm, PR interval > 155 mv, QRSvm >1.91 mV, RtQRSvm >1.8 mV and SPQRST angle >92.3 mV with p values <0.001 to 0.018. ConclusionWe demonstrate the importance of ECG/VCG monitoring in the Fontan population and suggest specific indicators of late complications and mortality.

Electrocardiographic proarrhythmic changes in pregnancy of women with CHD.

Pregnancy-related physiological adaptations result in increased heart rate as well as electrocardiographic changes such as a mean QTc prolongation of 27 ms. Pregnant women with CHD are at increased risk for cardiovascular complications. The aim of this study was to identify risk factors for abnormally prolonged QTc interval-a risk factor for ventricular arrhythmias-in pregnant women with CHD. Retrospective longitudinal single-centre study. Pre-pregnancy demographic and electrocardiographic risk factors for abnormal QTc duration during pregnancy of (a) > 460 ms and (b) >27 ms increase were analyzed. Eighty-three pregnancies in 63 women were included, of which three had documented arrhythmias. All five Modified World Health Organization Classification of Maternal Cardiovascular Risk (mWHO) classeswere represented, with 15 pregnancies (18.1%) in mWHO class I, 26 (31.3%) in mWHO II, 28 (33.7%) in mWHO II-III, 11 (13.3%) in mWHO III, and three pregnancies (3.6%) in mWHO class IV. Heart rate and QTc interval increased, while QRS duration and PR interval shortened during pregnancy. QTc duration of > 460 ms was associated with increased pre-pregnancy QTc interval, QRS duration, and weight, as well as body mass index. QTc increase of > 27 ms was associated with increased heart rate prior to pregnancy. No significant associations of electrocardiographic changes with mWHO class or CHD type were identified. Increased QTc in pregnant women with CHD was associated with being overweight or having higher heart rate, QRS, or QTc duration prior to pregnancy. These patients should be monitored closely for arrhythmias during pregnancy.

The effect of motor imagery and action observation on autonomic functions in patients with chronic stroke

ABSTRACT Objectives This study aimed to investigate the effects of motor imagery (MI), action observation (AO), and action execution (AE) interventions on the autonomic nervous system (ANS) in individuals with chronic stroke. Methods This was a single-center, randomized, case-control study. Thirty-six patients were randomly assigned to MI (n = 10), AO (n = 15), and the AE group (n = 11). Heart rate (HR)-based measurements (HR, heart rate variability (HRV)) and blood pressure were evaluated before the practice of each group. In the MI group, participants were instructed to imagine themselves walking at their own comfortable pace for 5 minutes. Meanwhile, in the AO group, participants were shown a video of a person walking for 5 minutes. Finally, in the AE group, participants were instructed to actually walk for 5 minutes. Then, all measurements were taken again. Results A statistically significant difference was found in HR and mean RR interval within the AE group (p < 0.05). There was a statistically significant difference in the Root Mean Square of Successive Differences Between Normal Heartbeats (RMSSD) (ms) within the AO group (p < 0.05). There was a significant difference in HR and mean RR intervals (ms) between groups (p < 0.05). According to post-hoc analyses, HR was statistically significantly higher in the AE group compared to the other groups, and the mean RR interval was statistically significantly lower (p < 0.05). Conclusions In conclusion, in patients with chronic stroke, AE and AO may affect ANS by increasing sympathetic activation. It is recommended for future studies to evaluate whether patients actually engage in imagery during the MI task.

Circulating noradrenaline leads to release of neuropeptide Y from cardiac sympathetic nerve terminals via activation of β-adrenergic receptors.

Cardiac disease is marked by sympathoexcitation and elevated levels of noradrenaline (NA) and cotransmitter neuropeptide Y (NPY). Increased NPY levels are associated with a greater risk of ventricular arrhythmias and mortality. Nonetheless, the factors that cause NPY release remain poorly understood. We hypothesized that circulating catecholamines might lead to NPY release from myocardial sympathetic nerve terminals via a β-receptor-mediated mechanism that enhances sympathoexcitation. Ventricular interstitial NA and NPY levels were measured in six Yorkshire pigs after i.v. administration of NA (1mg) and before and after propranolol infusion (1mg/kg). Real-time interstitial NPY levels were measured using ventricular capacitive immunoprobes (CIs) affixed with NPY antibodies and quantified as the change in CI input current (INPY ) upon binding of NPY. Interstitial NA was measured with adjacent fast-scan cyclic voltammetry probes (INA ). A left ventricular pressure catheter and continuous ECGs were used for haemodynamic recordings, and an epicardial 56-electrode sock was used for measurements of activation recovery interval, a surrogate of action potential duration. Upon administration of NA, heart rate and left ventricular pressure increased, and activation recovery interval shortened. Notably, NA significantly increased interstitial myocardial NPY levels. After propranolol, changes in heart rate and activation recovery interval were largely mitigated. The INA increased to a similar extent post-propranolol vs. pre-propranolol, but changes in INPY were significantly reduced post-propranolol. Coronary sinus plasma analyses confirmed fast-scan cyclic voltammetry and CI findings. Hence, this study demonstrates that circulating NA induces NPY release from ventricular sympathetic nerve terminals, the mechanism for which is mediated via β-adrenergic receptors and can be blocked by the non-selective β-blocker, propranolol. KEY POINTS: Cardiovascular disease is characterized by sympathovagal imbalance, with increased plasma noradrenaline (NA) and neuropeptide Y (NPY) concentrations. Increased NPY levels are associated with increased ventricular arrhythmias and mortality in heart failure. Limited data are available on the specific factors that cause NPY release. In this study, fast-scan cyclic voltammetry and capacitive immunoprobes were used to allow for real-time in vivo measurements of interstitial myocardial neurotransmitters and neuropeptides, respectively. Using an in vivo porcine model with cardiac fast-scan cyclic voltammetry and capacitive immunoprobes, it was shown that systemic NA can increase ventricular interstitial NPY levels, suggesting that NA induces NPY release from postganglionic sympathetic nerves. The release of NPY was blocked by administration of the non-selective β-blocker propranolol, suggesting that release of NPY is dependent on activation of β-adrenergic receptors by NA.