Interval Duration Research Articles

Hysteresis and bistability in synaptic transmission modeled as a chain of biochemical reactions with a positive feedback

In this paper, we employ computational analysis to investigate the long-term potentiation (LTP) and memory formation in synapses between neurons. We use a mathematical model describing the synaptic transmission as a signal transduction pathway with a positive feedback loop formed by diffusion of nitric oxide (NO) to the presynaptic site. We found that the model of synaptic transmission exhibits a hysteresis-like behavior, where the strength of synaptic transmission depends not just on instantaneous interstimulus intervals, but also on the history of activity. The switching between resting and memory states can be induced by physiologically relevant and moderate (less than 50%) changes in the duration of interstimulus intervals.

Analysis of the clinical characteristics and risk factors associated with contralateral hip fracture after initial hip fracture in elderly patients: a retrospective cohort study

Fractures of the contralateral hip may easily occur in elderly patients after an initial hip fracture. The aim of this study was to investigate the clinical characteristics and major predisposing risk factors of contralateral hip fracture after initial hip fracture in the elderly, to provide a clinical basis for preventing contralateral hip fracture. The data of 1586 patients who had sustained first or second hip fractures and had been surgically treated in our department were retrospectively analyzed. Potential predictive factors for contralateral hip fracture and descriptive statistics associated with surgery (such as blood loss, operation time, and length of hospital stay) were recorded. Of these patients, 133 (8.4%) suffered contralateral hip fracture. The rates of contralateral fracture after femoral neck and intertrochanteric fracture were 5.4% and 10.7% respectively (P < 0.01). Fifty-four cases of contralateral hip fracture occurred within one year, an incidence of 40.6%, while 95 cases (71.4%) and 105 cases (78.9%) occurred within two and three years, respectively, with a interval duration of 21.6 months. The risk factors for contralateral hip fracture were found to be age, type of first fracture, bone mineral density, the Singh index, and concomitant internal medical diseases, which were found to be significantly associated with an increased risk of contralateral hip fracture in multivariate logistic regression analysis (P < 0.05). In conclusion, the presence of concomitant internal diseases, type of first fracture, bone mineral density, the Singh index, and age were found to be significant predictors of the risk of contralateral hip fracture in elderly patients after a first hip fracture.

A training goal-oriented categorization model of high-intensity interval training.

There are various categorization models of high-intensity interval training (HIIT) in the literature that need to be more consistent in definition, terminology, and concept completeness. In this review, we present a training goal-oriented categorization model of HIIT, aiming to find the best possible consensus among the various defined types of HIIT. This categorization concludes with six different types of HIIT derived from the literature, based on the interaction of interval duration, interval intensity and interval:recovery ratio. We discuss the science behind the defined types of HIIT and shed light on the possible effects of the various types of HIIT on aerobic, anaerobic, and neuromuscular systems and possible transfer effects into competition performance. We highlight various research gaps, discrepancies in findings and not yet proved know-how based on a lack of randomized controlled training studies, especially in well-trained to elite athlete cohorts. Our HIIT "toolbox" approach is designed to guide goal-oriented training. It is intended to lay the groundwork for future systematic reviews and serves as foundation for meta-analyses.

Мікроциркуляція та варіабельність серцевого ритму при хронічній ішемічній хворобі серця і COVID-19

COVID-19 is associated with a wide range of negative effects on the cardiovascular system. The aim of our study was to investigate the impact of COVID-19 on the interdependence of changes in the microcirculation system and heart rate variability in patients with chronic coronary artery disease (CAD). An ECG study was performed in 12-lead leads, as well as 24-hour Holter ECG monitoring and laser Doppler flowmetry (LDF). Patients were divided into 3 groups. Group 1 included patients with coronary artery disease (n = 32), group 2 - with coronary artery disease in combination with COVID-19 (n = 35), and group 3 - with COVID-19 (n = 35). The control group consisted of 30 conditionally healthy individuals. All subjects were determined: microcirculation index, capillary blood flow reserve of the occlusion test, as well as nitroglycerin test and wavelet transform indicators (the relationship between the frequency and amplitude of microcirculatory oscillations, which are divided into endothelial, neurogenic, myogenic, respiratory and cardiac mechanisms of microcirculation regulation). The deterioration of endothelial function, as measured by the maximum amplitude of endothelial flux motions, should be noted, and a decrease in the endotheliumdependent and endothelium-independent components of microcirculation regulation. The capillary blood flow reserve of the occlusion test in patients with CAD in combination with COVID-19 was lower than in patients with CAD (group 1) and COVID-19 (group 3). In patients of the study groups, the total heart rate variability decreased, parasympathetic activity was weakened, and the QT interval duration and its variability increased compared with controls. These changes were most pronounced in patients with coronary artery disease in combination with COVID-19 in terms of the standard deviation of all intervals, the parasympathetic component of regulation, and both characteristics of the QT interval. Thus, patients with chronic CAD and concomitant COVID-19, along with endothelial dysfunction and worsening venous outflow, showed signs of autonomic dysregulation and increased QT interval duration and variability. Additional consideration of the characteristics of the microcirculatory bed, heart rate variability and QT interval is advisable in the examination system of such patients.

Effects of Short-Rest Interval Time on Resisted Sprint Performance and Sprint Mechanical Variables in Elite Youth Soccer Players

This study explored the impact of short rest intervals on resisted sprint training in elite youth soccer players, specifically targeting enhanced initial-phase explosive acceleration without altering sprint mechanics. Fifteen U19 soccer players participated in a randomized crossover design trial, executing two sprint conditions: RST2M (6 sprints of 20 m resisted sprints with 2 min rest intervals) and RST40S (6 sprints of 20 m resisted sprints with 40 s rest intervals), both under a load equivalent to 30% of sprint velocity decrement using a resistance device. To gauge neuromuscular fatigue, countermovement jumps were performed before and after each session, and the fatigue index along with sprint decrement percentage were calculated. Interestingly, the results indicated no significant differences in sprint performance or mechanical variables between RST2M and RST40S, suggesting that the duration of rest intervals did not affect the outcomes. Horizontal resistance appeared to mitigate compensatory patterns typically induced by fatigue in short rest periods, maintaining effective joint movement and hip extensor recruitment necessary for producing horizontal ground forces. These findings propose a novel training strategy that could simultaneously enhance sprint mechanics during initial accelerations and repeated sprint abilities for elite youth soccer players—a methodology not previously employed

Enhancing sp3 formation in DLC on low thermal conductivity substrate: Interval deposition minimizing ion energy sensitivity

Depositing sp3-rich diamond-like carbon (DLC) on low thermal conductivity substrates is difficult due to the high sensitivity of sp3 formation to ion energy. This sensitivity is attributed to the heating effect of ion bombardment during plasma-enhanced chemical vapor deposition (PECVD) processing. This study introduced an interval deposition method aimed at minimizing the ion energy sensitivity, thereby achieving sp3-rich DLC deposition and broadening the process window. The variation in sp3 content of deposited DLC showed that the interval deposition can enhance sp3 formation, which is particularly significant when the single deposition duration is ≤1 s and the ratio of interval duration to deposition duration is ≥3. Deposition experiments with varying bias voltages confirmed that the ion energy sensitivity of sp3 formation in DLC can be effectively reduced by the proposed method. The analysis of transient film temperature during the deposition process revealed that this method took effect by limiting the temperature elevation of the film. Performance comparison showed that the adhesion of films to the substrate was improved by 138 % using the interval deposition method, compared to the traditional continuous deposition. This user-friendly and high-tolerance deposition method can significantly advance the application fields of DLC coatings.

The causal relationship between sarcopenia-related traits and ECG indices - A mendelian randomization study

BackgroundSarcopenia is a common geriatric condition closely associated with cardiovascular diseases and other health issues. This study aims to investigate the causal relationship between sarcopenia-related traits and electrocardiogram(ECG) indices. MethodsWe conducted a comprehensive analysis utilizing summary data from genome-wide association studies (GWAS) associated with sarcopenia-related traits, including hand grip strength, lean body mass, and walking pace. ECG indices included PR interval, PP interval, ST duration, QRS duration and T wave duration. The primary analytical method employed was the inverse variance-weighted method (IVW). ResultsAccording to our study findings, we identified a significant association between sarcopenia-related traits and ECG indices. Specifically, we observed a positive correlation between increased muscle mass and certain ECG indices. For instance, increased limb muscle mass (including left arm, right arm, left leg, and right leg) was associated with prolonged PR interval and QRS duration. This suggests that enhancing muscle mass may impact the timing of cardiac electrical activity. Additionally, increased whole-body fat-free mass showed similar associations with cardiac electrical activity. ConclusionSarcopenia-related traits have a unidirectional causal relationship with ECG indices, indicating that sarcopenia affects cardiac electrical activity.

Multiplexing intensity and frequency sensations for artificial touch by modulating temporal features of electrical pulse trains.

In neural prostheses, intensity modulation of a single channel (i.e., through a single stimulating electrode) has been achieved by increasing the magnitude or width of each stimulation pulse, which risks eliciting pain or paraesthesia; and by changing the stimulation rate, which leads to concurrent changes in perceived frequency. In this study, we sought to render a perception of tactile intensity and frequency independently, by means of temporal pulse train patterns of fixed magnitude, delivered non-invasively. Our psychophysical study exploits a previously discovered frequency coding mechanism, where the perceived frequency of stimulus pulses grouped into periodic bursts depends on the duration of the inter-burst interval, rather than the mean pulse rate or periodicity. When electrical stimulus pulses were organised into bursts, perceived intensity was influenced by the number of pulses within a burst, while perceived frequency was determined by the time between the end of one burst envelope and the start of the next. The perceived amplitude was modulated by 1.6× while perceived frequency was varied independently by 2× within the tested range (20-40 Hz). Thus, the sensation of intensity might be controlled independently from frequency through a single stimulation channel without having to vary the injected electrical current. This can form the basis for improving strategies in delivering more complex and natural sensations for prosthetic hand users.

Chuvas intensas no estado do Acre, Amazônia ocidental

ABSTRACT Preventing the occurrence of extreme hydrological events exceeds the current abilities of humanity. However, using adequate tools to estimate the probability associated with different values of hydrological variables, such as heavy rainfall, can help mitigate social and environmental damage. This study aimed to verify the hypothesis that the records of maximum rainfall, at different intervals of duration, in the three main rainfall stations in the state of Acre fit the log-normal distribution of two parameters (LN2) and, therefore, to evaluate the events of heavy rainfalls, based on the association between the duration of the rain and the return period. The equations conformed to the classic model of the LN2 model using the method of maximum likelihood once the baseline assumption of stationarity was met using the Mann-Kendall test. Adherence to the model was verified using the Anderson-Darling test. The adjusted distributions allowed for estimating the rainfall intensity at different durations and return periods for the cities of Cruzeiro do Sul, Tarauacá, and Rio Branco and are relevant elements for planning actions aimed at strengthening the components of water safety in the state of Acre.

Phosphorylation of cardiac sodium channel at Ser571 anticipates manifestations of the aging myopathy.

Diastolic dysfunction and delayed ventricular repolarization are typically observed in the elderly, but whether these defects are intimately associated with the progressive manifestation of the aging myopathy remains to be determined. In this regard, aging in experimental animals is coupled with increased late Na+ current (INa,L) in cardiomyocytes, raising the possibility that INa,L conditions the modality of electrical recovery and myocardial relaxation of the aged heart. For this purpose, aging male and female wild-type (WT) C57Bl/6 mice were studied together with genetically engineered mice with phosphomimetic (gain of function, GoF) or ablated (loss of function, LoF) mutations of the sodium channel Nav1.5 at Ser571 associated with, respectively, increased and stabilized INa,L. At ∼18 mo of age, WT mice developed prolonged duration of the QT interval of the electrocardiogram and impaired diastolic left ventricular (LV) filling, defects that were reversed by INa,L inhibition. Prolonged repolarization and impaired LV filling occurred prematurely in adult (∼5 mo) GoF mutant mice, whereas these alterations were largely attenuated in aging LoF mutant animals. Ca2+ transient decay and kinetics of myocyte shortening/relengthening were delayed in aged (∼24 mo) WT myocytes, with respect to adult cells. In contrast, delayed Ca2+ transients and contractile dynamics occurred at adult stage in GoF myocytes and further deteriorated in old age. Conversely, myocyte mechanics were minimally affected in aging LoF cells. Collectively, these results document that Nav1.5 phosphorylation at Ser571 and the late Na+ current modulate the modality of myocyte relaxation, constituting the mechanism linking delayed ventricular repolarization and diastolic dysfunction.NEW & NOTEWORTHY We have investigated the impact of the late Na current (INa,L) on cardiac and myocyte function with aging by using genetically engineered animals with enhanced or stabilized INa,L, due to phosphomimetic or phosphoablated mutations of Nav1.5. Our findings support the notion that phosphorylation of Nav1.5 at Ser571 prolongs myocardial repolarization and impairs diastolic function, contributing to the manifestations of the aging myopathy.

Symptom-Free Intervals Following Laser Wedge Excision for Recurrent Idiopathic Subglottic Stenosis.

Analyze the duration of symptom-free intervals following laser wedge excision (LWE) for recurrent idiopathic subglottic stenosis (iSGS). Secondary aim includes evaluating the influence of patient-related or disease factors. Retrospective review. Tertiary center. Review of iSGS patients who underwent LWE between 2002 and 2021. LWE patients without prior airway surgery were labeled LWE primary (LWEP) and those with prior history of dilation were labeled LWE secondary (LWES). A conditional frailty repeated events model was used to analyze the median time to recurrence (MTR) for each nth recurrence. Secondary analysis included stratification by use of medical therapy and initial preoperative characteristics of scar (Myer-Cotton grade, distance between the glottis and superior-most aspect of scar, DGS; length of scar, DL). Two hundred and ten iSGS patients underwent LWE (131 LWEP, 79 LWES). The proportion of patients experiencing at least 1, 3, 6, and 12 recurrences, respectively, was 68.0% (n = 143), 40.7% (n = 85), 20.0% (n = 42), and 5.2% (n = 11). There was exponential time-shortening from the 1st to 12th recurrence (P < .0001). While MTR was 4.1 years after the first LWE, this fell to 2.8, 1.7, 1.0, and 0.7 years for the 2nd, 3rd, 6th, and 12th recurrences. Furthermore, LWEP patients experienced longer MTR than LWES counterparts within the first 6 recurrences (P < .01). There was no significant relationship between intersurgical interval and medication adherence, DL, DGS, or grade for recurrences beyond the first (P = .207, P = .20, P = .43, P = .16). Symptom-free intervals in iSGS shorten with each subsequent recurrence and LWE. The difference in MTR between LWEP and LWES groups was significant within the first 6 recurrences with LWEP having longer MTR.

Exploring the utility of process scores in elucidating the role of cognitive and affective factors that influence verbal fluency performance in Parkinson’s disease

Objectives Cognitive and affective factors have been implicated in verbal fluency (VF) performance in Parkinson’s disease (PD). This exploratory study aimed to investigate the relationships between cognitive and affective variables on traditional (“core”) and "process” (error and interval) scores of VF and elucidate unique information these scores may provide regarding mechanisms underlying VF. Methods Sixty-two PD patients without dementia completed clinical neuropsychological examinations consisting of attention, processing speed, language, executive functioning, visuospatial, memory, and mood measures. Hierarchical regression and negative binomial regression analyses were used to evaluate relationships between outcome and predictor variables. Results Generativity results revealed that processing speed and working memory explained up to 34% of the variance of total letter fluency responses (p = <.001) and processing speed explained 24% of the variance for total semantic fluency (p = .003). For category switching generativity, only age predicted 20% of the variance (p = .01). Two executive functioning measures were negatively associated with error production over the duration (b = −.055, p = .028; b = −.062, p = .004) and final 45-second interval (b = −.072, p = .003; b = −.044, p = .033) of the category switching task. In the initial 15-second task interval, a positive predictive relationship between error production and indifference apathy (b = .616, p = .044) was demonstrated. Conclusions Findings demonstrate the potential utility of "process” scores in detecting subtle cognitive impairment in Parkinson’s disease patients without dementia and tentatively evidence the role of indifference apathy in task initiation.

Temporal dynamics of short-term neural adaptation across human visual cortex.

Neural responses in visual cortex adapt to prolonged and repeated stimuli. While adaptation occurs across the visual cortex, it is unclear how adaptation patterns and computational mechanisms differ across the visual hierarchy. Here we characterize two signatures of short-term neural adaptation in time-varying intracranial electroencephalography (iEEG) data collected while participants viewed naturalistic image categories varying in duration and repetition interval. Ventral- and lateral-occipitotemporal cortex exhibit slower and prolonged adaptation to single stimuli and slower recovery from adaptation to repeated stimuli compared to V1-V3. For category-selective electrodes, recovery from adaptation is slower for preferred than non-preferred stimuli. To model neural adaptation we augment our delayed divisive normalization (DN) model by scaling the input strength as a function of stimulus category, enabling the model to accurately predict neural responses across multiple image categories. The model fits suggest that differences in adaptation patterns arise from slower normalization dynamics in higher visual areas interacting with differences in input strength resulting from category selectivity. Our results reveal systematic differences in temporal adaptation of neural population responses between lower and higher visual brain areas and show that a single computational model of history-dependent normalization dynamics, fit with area-specific parameters, accounts for these differences.

Histologic and Quality Assessment of Genotype-Tissue Expression (GTEx) Research Samples: A Large Postmortem Tissue Collection.

The National Institutes of Health Genotype-Tissue Expression (GTEx) project was developed to elucidate how genetic variation influences gene expression in multiple normal tissues procured from postmortem donors. To provide critical insight into a biospecimen's suitability for subsequent analysis, each biospecimen underwent quality assessment measures that included evaluation for underlying disease and potential effects introduced by preanalytic factors. Electronic images of each tissue collected from nearly 1000 postmortem donors were evaluated by board-certified pathologists for the extent of autolysis, tissue purity, and the type and abundance of any extraneous tissue. Tissue-specific differences in the severity of autolysis and RNA integrity were evaluated, as were potential relationships between these markers and the duration of postmortem interval and rapidity of death. Tissue-specific challenges in the procurement and preservation of the nearly 30 000 tissue specimens collected during the GTEx project are summarized. Differences in the degree of autolysis and RNA integrity number were observed among the 40 tissue types evaluated, and tissue-specific susceptibilities to the duration of postmortem interval and rapidity of death were observed. Ninety-five percent of tissues were of sufficient quality to support RNA sequencing analysis. Biospecimens, annotated whole slide images, de-identified clinical data, and genomic data generated for GTEx represent a high-quality and comprehensive resource for the scientific community that has contributed to its use in approximately 1695 articles. Biospecimens and data collected under the GTEx project are available via the GTEx portal and authorized access to the Database of Genotypes and Phenotypes; procedures and whole slide images are available from the National Cancer Institute.

Biomarkers of inflammation and neoangiogenesis in premature rupture of membranes

BACKGROUND: Premature rupture of membranes complicates up to 2–10% of full-term pregnancies and up to 40% of all premature pregnancies. It is believed that the main cause of premature rupture of membranes is inflammation caused by both infectious agents and autoimmune processes. Numerous studies are aimed at searching for biomarkers that can predict inflammation in premature rupture of membranes. AIM: The aim of this study was to determine the levels of pro-inflammatory cytokines such as interleukin-6, -18 and procalcitonin, as well as interferon-α and soluble endoglin, in the blood serum of pregnant women with premature rupture of membranes and women in labor with timely discharge of amniotic fluid and evaluate the possibility of using these parameters to optimize obstetric tactics. MATERIALS AND METHODS: This study included 69 patients delivered at the Clinic of Obstetrics and Gynecology of the Academician I.P. Pavlov First Saint Petersburg State Medical University from January 2022 to March 2023. The main study group consisted of 53 pregnant women with premature rupture of membranes, the control group included 16 women with term labor and timely discharge of amniotic fluid, or amniotomy performed in the first stage of labor. The levels of interleukin-6, -18, interferon-α, procalcitonin and soluble endoglin in maternal peripheral blood were assessed using enzyme-linked immunosorbent assay. Pregnancies complicated by severe preeclampsia, placenta abruption and chronic maternal diseases in the acute stage were excluded from the study. RESULTS: At the time of rupture, the minimum gestational age was 33+0 weeks and the maximum age — 41+3 weeks. The median duration of the anhydrous interval was 31.8 hours. No significant differences in interleukin-6, -18, procalcitonin and soluble endoglin concentrations were revealed in the main and control groups, interferon-α level being higher in the comparison group. The median concentration of interferon-α in pregnant women with premature rupture of membranes was 1.64 pg/ml and in women with timely discharge of amniotic fluid — 4.61 pg/ml (p = 0.001). A weak direct correlation was revealed between soluble endoglin and interleukin-18 concentrations (R = 0.26; p = 0.03), as well as a moderate direct correlation between soluble endoglin and procalcitonin levels (R = 0.4; p 0.001). CONCLUSIONS: The study did not reveal differences in the concentrations of interleukin-6, -18, procalcitonin and soluble endoglin in the comparison groups. A decrease in interferon-α level in the blood in pregnant women increases the risk of developing premature rupture of membranes. The correlations between soluble endoglin and interleukin-18 or procalcitonin concentrations may indicate an association between different mechanisms of the pathogenesis of premature rupture of membranes. In this regard, an integrated approach and analysis of a combination of several cellular bioregulators are eligible to predict infectious complications in premature rupture of membranes.

Mobile ECG devices in pediatric cardiology: efficacy and accuracy of smart watch and hand-held device in healthy children

Abstract Background and Aim Pediatric arrhythmias require accurate electrocardiogram (ECG) assessment for diagnosis and management. Mobile ECG devices, such as smart watch based and hand-held devices, offer potential advantages in terms of portability and accessibility. This study aimed to compare the efficancy and diagnostic accuracy of ECG tracings obtained using a smart watch and a hand-held device with standard 12-lead ECG tracings in healthy children. Methods ECG data were acquired from healthy pediatric subjects (n=30) aged 4 to 18 years using the smart watch, hand-held device, and standard 12-lead ECG. Single leads were acquired sequentially. The time required for ECG acquisition was recorded for each device. Subsequently, ECG leads were analyzed for voltage, duration, and morphology of waves and intervals, as well as ST segments. Qualitative assessment of leads included morphology comparison of waves and complexes to standard 12-lead ECG and using a physician based quality rating scale. Assessment was performed by two blinded pediatric electrophysiologists. Results We found significant differences in the time required to acquire ECG tracings between the smart watch, standard 12-lead ECG, and hand-held device, with the smart watch being notably slower (median 15 min, 4 min, 1 min, respectively). ECG leads obtained with the smart watch and hand-held device demonstrated comparability to standard 12-lead ECG tracings in terms of quantitative key parameters, including voltage (mV) and duration (ms) of waves and intervals. Qualitative assessment revealed good correlation of the hand-held device with standard 12-lead ECG, while the smart watch performed less well. Conclusions This study suggests that mobile ECG devices offer a diagnostic accuracy comparable to that of standard 12-lead ECGs in healthy children. While the smart watch may be slower in ECG acquisition, acquisition of all 12 standard ECG leads is feasible in this population. The potential of both included mobile devices for pediatric usage in specific clinical scenarios, such as remote monitoring or emergencies, is promising.Graphical Abstract

Relationship between ECG parameters and electrophysiological study in post-TAVI de novo left bundle branch block

Abstract Background The measurement of the HV interval in post-TAVI has a determining place in the most recent recommendations. However, its value, in addition to the post-TAVI ECG, remains debated. To describe the correlation in post-TAVI ECG and HV in case of de novo left bundle branch block and his correlation to PR interval prolongation. Methods Prospective, open-label study with 12 months follow-up. From June 2015 to November 2018, TAVR recipients were included at 10 centers in the French Multicenter LBBB-TAVR study. 183 TAVR recipients (64% self-expanding valve) had a new-onset LBBB after TAVR persisting for more than 24 hours. HV interval was assessed by intracardiac EPS and compared to ECG parameter on the day of EPS. Results 1631 ECGs were recovered and double-read. On the day of EPS the mean PR was 224±51 ms, the mean QRS duration was 148±18 ms. The PR increases after TAVI by a maximum of 60±43 ms to reach a mean maximum PR of 252±55 ms. It increases progressively in the post-procedure period from 25±37ms, until the 4th day (44±32ms, p&amp;lt;0.001). The mean HV interval delay was 62±14 ms, the AH was 140±63 ms. The HV interval was weakly correlated with the duration of the PR interval (0.19), the AH interval had a correlation of 0.72. In logistic regression, PR ≥ 240 ms and QRS ≥ 150 ms were independent predictor of HV prolongation (HR 7.6 [3.0 - 12.2], p=0.001 and 5.9 [1.6 - 10.3], p=0.007). The rate of conduction disturbance at 1 year in case of prolonged HV, QRS ≥ 150 ms and PR ≥ 240 ms was 57% vs. 27% if HV &amp;lt; 70 ms (p&amp;lt;0.001). Conclusions In post-TAVI de novo left bundle branch block, PR interval prolongation is a dynamic, transient process driven by an alteration of atrioventricular node. The HV interval prolongation is poorly correlated to post-TAVI PR prolongation and LBBB duration.Correlation between ECG and EP studyConduction disorders after TAVR

Association of leukocyte telomere length with cardiac conduction disease and sick sinus syndrome

Abstract Background Cardiac conduction disease (CCD) and sick sinus syndrome (SSS) may be related to a degenerative process. Leukocyte telomere length (LTL) is associated with the aging process and age-related degenerative diseases. We aimed to investigate the association between LTL and the risks of CCD/SS, and to explore whether LTL is related with cardiovascular imaging and electrocardiographic (ECG) changes. Methods This is a population-based cross-sectional study of UK Biobank participants without history of CCD/SSS recruited from 2006 to 2010. LTL was measured using a quantitative polymerase chain reaction method. Cardiovascular measurements were derived from cardiovascular magnetic resonance using machine learning. The median (IQR) duration of follow-up was 12.0 (11.3-12.7) years. The associations of LTL with imaging and ECG measurements and incident CCD/SSS were evaluated by multivariable regression models. Results Among the 412,452 white participants, 188,891 (45.8%) were male, with a mean age of 57.3 years. Longer LTL was independently associated with positive cardiac remodeling, including higher left ventricular mass, larger atrial volume, and increased atrial stroke volumes. However, no significant associations were observed with ECG findings including PR interval and P-wave duration. 11991 (2.6%) participants developed CCD and 984 (0.2%) developed SSS. Longer LTL was not associated with younger age. However, longer LTL was not associated with a lower risk of incident CCD (LTL fourth quartile vs. first quartile: hazard ratio, 0.98; 95% CI, 0.97-1.0; P = 0.057) or SSS (LTL fourth quartile vs. first quartile: hazard ratio, 0.98; 95% CI, 0.92-1.05; P = 0.554). Conclusions In this cross-sectional study, longer LTL was associated with a larger atrial size with better atrial function in middle age, but not with ECG changes. However, longer LTL was not associated with a lower risk of incident CCD and SSS.

High-resolution repolarization changes preceding short-coupled ectopy in idiopathic ventricular fibrillation, and effects of quinidine

Abstract Background Idiopathic ventricular fibrillation (VF) is linked to early repolarization, increased repolarization heterogeneity, and (short-coupled) premature ventricular complexes (PVCs). Quinidine, an antiarrhythmic drug with class-IA and -III effects, reduces the occurrence of PVCs and VF, but its effects on repolarization have not yet been studied at the whole-heart level in idiopathic-VF patients. Purpose To study dynamic changes in repolarization preceding short-coupled PVCs using noninvasive electrocardiographic imaging (ECGI) in a patient with idiopathic VF, and the antiarrhythmic effects of quinidine. Methods ECGI was performed during sinus rhythm in a 61-year-old male with an ICD (secondary prevention; 2.5 mg nebivolol daily) two days after recurrent idiopathic VF (Fig. A). This was done 1) at baseline, 2 minutes before short-coupled ectopy ("baseline"); 2) at baseline, 10 seconds before the short-coupled PVC ("pre PVC"); and 3) at 2 hours after start of quinidine 200 mg ("on-quinidine"). The ECGI procedure consisted of a 224-electrode body surface potential map and a contrast-enhanced CT scan to obtain torso and heart geometries. After reconstruction of epicardial unipolar electrograms (UEGs), local activation and repolarization times (ATs and RTs) were derived from UEGs by assessing the steepest downslope of the QRS complex and steepest upslope of the T waves, respectively, of 10-second signal-averaged beats. AT and RT duration (first to last AT or RT) were assessed. Results At baseline, QRS duration and QT interval measured 107 ms and 343 ms, respectively, on the standard 12-lead ECG. ECGI-derived epicardial AT duration was 72 ms, and RT histogram span 92 ms. The coupling interval of the PVC that triggered VF in the ICD readout was 340 ms (Fig. A). During 44 minutes of ECGI, 157 short-coupled PVCs from the moderator-band region were recorded (Fig. B; no tachycardia or VF). Just prior to a PVC, epicardial early repolarization at the PVC origin decreased by 26 ms (star in Figs. C-E), and the RT histogram broadened to 109 ms (Fig. E). While on-quinidine, (25 minutes; QRS duration 107 ms, QT interval 419 ms), epicardial repolarization was prolonged (Fig. C/D), also at the site of abnormal impulse formation. Quinidine had increased the epicardial AT duration to 79 ms, and RT histogram span to 133 ms. PVCs were completely suppressed. The patient remained free of sustained arrhythmias while on-quinidine. Conclusion(s) In this case of short-coupled idiopathic VF, epicardial early repolarization shortened momentarily prior to abnormal impulse formation. We found dynamic substrate-trigger characteristics that likely facilitate reentrant excitation. Quinidine prolonged the duration of epicardial activation and repolarization, suppressing the ectopy and VF recurrence.

Additional factors associated with sudden cardiac death in HCM patients

Abstract Background Hypertrophic cardiomyopathy (HCM) is a primary myocardial disease characterized by an increase in the thickness of the left ventricular (LV) wall, which is not explained only by abnormal loading conditions. Sudden cardiac death (SCD) is the most devastating complication of HCM occurring in asymptomatic or younger patients without warning. Purpose To evaluate additional SCD risk factors in Ukrainian population of HCM patients. Materials and methods We retrospectively evaluated 350 consecutive HCM patients that were followed from 2006 to 2021 in our Cardiological Department. General clinical examination, standard 12-lead ECG, transthoracic echocardiography and 24 hours Holter ECG monitoring data were estimated. The 5-year SCD risk was calculated according to the HCM Risk-SCD score. The endpoint of the study was SCD and its surrogates, including adequate performance of the implantable cardioverter-defibrillator and successful resuscitation. Results Follow-up time was 5.0 (1.5-9.5) years. During this time, 16 patients (4.6%) reached the end point, which was 0.9%/year. According to the HCM Risk-SCD score, 5 (31.3%) of this group had a high risk of SCD (≥ 6%) and 3 (18.8%) had an intermediate risk (≥ 4% and &amp;lt; 6%). In multivariable Cox regression analysis adjusted for conventional SCD risk factors it was found that independent predictors of SCD were unexplained syncope (HR 3.81, 95% CI 1.11-13.12, p=0.034), systolic blood pressure (SBP) (HR 0.97 , 95% CI 0.94- 0.99, p=0.026), "infarct-like" ST elevation on ECG (HR 6.81, 95% CI 2.09-22.16, p=0.001) and PQ interval duration (HR 1.03, 95% CI 1.01-1.05, p=0.002), Harrell's C-index 0.84, 95% CI 0.73-0.95, p &amp;lt; 0.0001). Conclusions In our study HCM Risk-SCD score predicted SCD or surrogates only in 50% of cases. In order to improve the risk stratification some additional independent predictors of SCD can be proposed. ECG parameters ("infarct-like" ST elevation and PQ interval duration) and level of SBP were found to have SCD predictive value.