24-h Recordings Research Articles

The Sleep–Waking Cycle and Experimental Models of Mutations in the Panx1 Gene

Objectives. To confirm the authors’ previous suggestion that mutations in the Panx1 gene (pannexin-1) may play an important role in the development of impairments to the sleep-waking cycle. Materials and methods. Studies were carried out using mice with knockout of the Panx1 gene. Experiments used continuous 24-h EEG recording of the EEG and motor activity. Results and conclusions. A statistically significant increase in the proportion of waking was found, due to a decrease in the slow-wave sleep phase (as compared with controls), particularly marked in the dark period of the day, along with an increase in motor activity. The results were compared with data obtained during investigation of a recently published case of a patient with a homozygous mutation in this gene. The possible physiological role of pannexin-1 protein in health and pathology is discussed.

Atrial premature depolarisations five days post electrical cardioversion are related to atrial fibrillation recurrence risk in horses.

The number of atrial premature depolarisations (APDs) is a known risk factor for atrial fibrillation (AF) recurrence in humans. To evaluate if the number of APDs over a 24-h period 5days post cardioversion predicts AF recurrence within 1year in horses, taking the multifactorial nature of AF into account. Retrospective case series. Eighty horses met these inclusion criteria: first AF episode, no AF recurrence within 5days post cardioversion, cardioversion by transvenous electrical cardioversion (TVEC), 24-h ECG recording and echocardiographic examination 5days post cardioversion, no antiarrhythmic treatment during the ECG recording and follow-up of minimum 1year. To compare the APD burden between the recurrence and non-recurrence group a Mann-Whitney U test was used. A multivariable survival model was built to identify additional risk factors for AF recurrence. The patient population mainly consisted of Warmbloods (93%). Twenty-six horses (33%) experienced AF recurrence within 1year. The number of APDs (median [range]) was significantly higher (P=0.01) in the recurrence group (15 [1-152]) compared with the non-recurrence group (7 [0-304]). In the multivariable survival model, APDs≥25/24h (hazard ratio [HR] 2.9, 95% confidence interval [CI] 1.2-6.8, P=0.02), mitral regurgitation (HR 8.6, 95% CI 2.6-28.9, P<0.001), left atrial active fractional area change ≤9.6% (HR 2.6, 95% CI 1.0-6.5, P=0.04) and lower body weight (HR 0.99, 95% CI 0.98-0.99, P=0.001) were significantly associated with AF recurrence. This study did not evaluate early AF recurrence within 5days. The results cannot necessarily be extrapolated to other treatment methods, as only horses converted by TVEC were included. The APD burden 5days post cardioversion could be a useful predictive value for AF recurrence within 1year in horses. However, other factors such as mitral regurgitation and atrial contractile function must also be taken into account.

Low deceleration capacity is associated with higher stroke risk in patients with paroxysmal atrial fibrillation.

Background:Deceleration capacity (DC) is a non-invasive marker for cardiac autonomic dysfunction; however, few studies have shown that the influence factors of cardiac autonomic dysfunction and the correlations between DC and stroke risk in paroxysmal atrial fibrillation (AF). We aimed to explore the influencing factors of abnormal DC and the relationships between DC and stroke risk in patients with paroxysmal AF.Methods:The study included hospitalized paroxysmal AF patients with DC measurements derived from 24-h Holter electrocardiography recordings taken between August 2015 and June 2016. Multivariable regression analysis was performed to evaluate the associations between correlated variables and abnormal DC values. The relationship between DC and ischemic stroke risk scores in patients with paroxysmal AF was analyzed.Results:We studied 259 hospitalized patients with paroxysmal AF (143 [55.2%] male, mean age 66.4 ± 12.0 years); 38 patients of them showed abnormal DC values. In the univariate analysis, age, hypertension, heart failure, and previous stroke/transient ischemic attack (TIA) were significantly associated with abnormal DC values. Among these factors, a history of previous stroke/TIA (odds ratio = 2.861, 95% confidence interval: 1.356–6.039) were independently associated with abnormal DC values in patients with paroxysmal AF. The abnormal DC group showed a higher stroke risk with the score of congestive heart failure, hypertension, age >75 years, diabetes mellitus, previous stroke and TIA (CHADS2) (2.25 ± 1.48 vs. 1.40 ± 1.34, t = −4.907, P = 0.001) and CHA2DS2-vascular disease, age 65–74 years and female category (VASc) (3.76 ± 1.95 vs. 2.71 ± 1.87, t = −4.847, P = 0.001) scores. Correlation analysis showed that DC was negatively correlated with CHADS2 scores (r = −0.290, P < 0.001) and CHA2DS2-VASc scores (r = −0.263, P < 0.001).Conclusions:Lower DC is closely associated with previous stroke/TIA, and is also correlated negatively with higher stroke risk scores in patients with paroxysmal AF. It could be a potential indicator of stroke risk in paroxysmal AF patients.

Prediction of mortality benefit based on periodic repolarisation dynamics in patients undergoing prophylactic implantation of a defibrillator: a prospective, controlled, multicentre cohort study

A small proportion of patients undergoing primary prophylactic implantation of implantable cardioverter defibrillators (ICDs) experiences malignant arrhythmias. We postulated that periodic repolarisation dynamics, a novel marker of sympathetic-activity-associated repolarisation instability, could be used to identify electrically vulnerable patients who would benefit from prophylactic implantation of ICDs by way of a reduction in mortality. We did a prespecified substudy of EUropean Comparative Effectiveness Research to Assess the Use of Primary ProphylacTic Implantable Cardioverter Defibrillators (EU-CERT-ICD), a prospective, investigator-initiated, non-randomised, controlled cohort study done at 44 centres in 15 EU countries. Patients aged 18 years or older with ischaemic or non-ischaemic cardiomyopathy and reduced left ventricular ejection fraction (≤35%) were eligible for inclusion if they met guideline-based criteria for primary prophylactic implantation of ICDs. Periodic repolarisation dynamics from 24-h Holter recordings were assessed blindly in patients the day before ICD implantation or on the day of study enrolment in patients who were conservatively managed. The primary endpoint was all-cause mortality. Propensity scoring and multivariable models were used to assess the interaction between periodic repolarisation dynamics and the treatment effect of ICDs on mortality. Between May 12, 2014, and Sept 7, 2018, 1371 patients were enrolled in our study. 968 of these patients underwent ICD implantation, and 403 were treated conservatively. During follow-up (median 2·7 years [IQR 2·0-3·3] in the ICD group and 1·2 years [0·8-2·7] in the control group), 138 (14%) patients died in the ICD group and 64 (16%) patients died in the control group. We noted a 43% reduction in mortality in the ICD group compared with the control group (adjusted hazard ratio [HR] 0·57 [95% CI 0·41-0·79]; p=0·0008). Periodic repolarisation dynamics significantly predicted the treatment effect of ICDs on mortality (adjusted p=0·0307). The mortality benefits associated with ICD implantation were greater in patients with periodic repolarisation dynamics of 7·5 deg or higher (n=199; adjusted HR 0·25 [95% CI 0·13-0·47] for the ICD group vs the control group; p<0·0001) than in those with periodic repolarisation dynamics less than 7·5 deg (n=1166; adjusted HR 0·69 [95% CI 0·47-1·00]; p=0·0492; pinteraction=0·0056). The number needed to treat was 18·3 (95% CI 10·6-4895·3) in patients with periodic repolarisation dynamics less than 7·5 deg and 3·1 (2·6-4·8) in those with periodic repolarisation dynamics of 7·5 deg or higher. Periodic repolarisation dynamics predict mortality reductions associated with prophylactic implantation of ICDs in contemporarily treated patients with ischaemic or non-ischaemic cardiomyopathy. Periodic repolarisation dynamics could help to guide treatment decisions about prophylactic ICD implantation. The European Community's 7th Framework Programme.

Abstract 046: Chronic Nicotine Inhalation Promotes the Development of Hypertension

While smoking is a proven risk factor for stroke and heart attacks, whether it contributes to the development of hypertension is still unclear. Nicotine inhalation is thought to activate the sympathetic nervous system and could contribute to the development of dysautonomia and blood pressure (BP) dysregulation. The purpose of this study was to investigate a possible relationship between chronic nicotine inhalation and the development of hypertension. C57BL/6 mice (male, 8-12 weeks of age) were exposed to air or nicotine vapor (daily, 12 h on/off) for 8 weeks. BP was recorded weekly for 24 h (telemetry). Nicotine exposure was assessed by weekly measurement of serum cotinine levels, which showed an average of 599.0 ±54.3 ng/ml in nicotine-exposed mice. Nicotine exposure induced a time-dependent increase in systolic BP. Notably, 24-h BP recordings showed that by the end of the 7 th week, systolic BP of nicotine-exposed mice was more often in the hypertensive zone (as defined by the area under the curve [AUC] above the 130 mmHg threshold within a 24-h recording) compared to their air-exposed counterparts (AUC: 555 ±299 vs. 112 ±30, P=0.012 , n=12). This hypertensive response was validated in angiotensin-II (Ang-II)-infused mice (450 ng/kg/min, s.c., AUC: 1358 ±939 vs. 112 ±30, P&lt;0.001 , n=5). At the end of nicotine exposure, urinary norepinephrine (NE) showed significant increase in both nicotine (108.9 ±9.8 vs. 79.53 ±5.7 ng/1ng creatinine, P=0.018 , n=9) and Ang-II groups (114.0 ±14 vs. 79.53 ±5.7 ng/1ng creatinine, P=0.016 , n=9), suggesting increased sympathetic activity in those mice. In addition, mice with global deletion of angiotensin converting enzyme type 2 (ACE2) showed a dramatic elevation in urinary NE level after nicotine exposure (157.8 ±8.5 vs. 79.53 ±5.7 ng/1ng creatinine, P&lt;0.001 , n=9). These data suggest that ACE2 might be protective against nicotine inhalation-mediated rise in sympathetic activity. In summary, chronic nicotine inhalation promotes the development of hypertension, and this could be mediated through the elevated activity of sympathetic nervous system. Experiments are ongoing to confirm sympatho-excitation and a possible involvement of the renin-angiotensin system in chronic nicotine inhalation-induced hypertension.

Atrial ectopy after pulmonary vein isolation and left heart reverse remodeling in patients with atrial fibrillation.

Maintenance of sinus rhythm after pulmonary vein isolation (PVI) for atrial fibrillation (AF) is associated with left atrial (LA) and ventricular (LV) reverse remodeling, although the degree varies among individuals. We hypothesized that frequent premature atrial complex (PAC) after PVI may attenuate the left heart reverse remodeling benefited from maintenance of sinus rhythm. We included 82 AF patients who underwent first-time PVI and 24-h Holter recordings at 6 months after PVI. All patients had no AF recurrence before this time. The number of PAC was categorized into tertiles:<90, 90-488 and>488 PACs/day. All patients underwent two-dimensional echocardiography and serum plasma B-type natriuretic peptide (BNP) measurement before and 6 months after PVI. LA reverse remodeling was defined as ≥15% decrease in LA volume index. There was no significant difference in the baseline characteristics among the PAC tertiles except for sex. Six months after PVI, LA volume index, LV mass index, and serum BNP levels were significantly decreased in lower and middle PAC tertiles (all P<.05), whereas no significant changes were observed in upper PAC tertile. Frequency of LA reverse remodeling was significantly lower in upper tertile of PAC compared with middle and lower tertiles (22.2%, 57.1%, and 59.3%, P<.001). Baseline LA volume index, changes in LV mass index, and the frequency of PAC were independently associated with LA reverse remodeling (all P<.05). Frequent PAC after PVI was associated with less left heart reverse remodeling in AF patients even without AF recurrence.

REPRODUCIBILITY OF BLOOD PRESSURE VALUES AND DIPPING ON 24-H AMBULATORY BLOOD PRESSURE MEASUREMENT IN A CHINESE POPULATION

Objective: The degree of reproducibility of ambulatory blood pressure measurements (ABPM) differ among studies. Reproducibility of absolute BP values and dipping status on ABPM was yet studied in Chinese population. This study aimed to investigate the reproducibility of ABPM in our Chinese population Design and method: Sixty-eight participants with diagnosed essential hypertension were recruited from a primary care teaching clinic from Aug 2017 to Jan 2018 in Hong Kong. All participants underwent 48-hour ABPM by a validated ABPM machine (ApenABP; Meditech, Hungary). The ABPM was conducted on usual working days. BP was measured every 30 minutes and sleep period was detected by a validated wrist actigraph machine (GT9X-BT; Pensacola, USA). Data obtained from the first 24-hour was compared to data obtained from the second 24-hour. Data was compared by paired t-test for continuous data and by McNemar's test for categorical data (e.g. dipping status). The degree of agreement was assessed by a Bland and Altman plots and Pearson's correlation. Results: When compared by t-test, mean BP value (awake, asleep and overall) did not significantly differ between the first and second 24-h. The correlation of BP values (overall mean BP, awake BP and asleep BP) from the 1st 24-h and 2nd 24-h showed excellent correlation ranged from 0.72 to 0.95 (p-value <0.001). The width of 95% limit of agreement for SBP in the BA-plot ranged from −8.6 to 8.6 mmHg, −10.2 to 10.2 mmHg, and from −14.7to 14.3 mmHg for overall average SBP, awake SBP and sleep SBP, respectively. When analyzed as a group by McNemar's test, the proportion of participants with non-dipping were not significantly different between first and second 24-h (p = 0.831). However, when defined by SBP, 42% of dippers on the 1st 24-h recording became non-dippers on the 2nd 24-h; while 27% of non-dippers on the 1st 24-h recording became dippers on the 2nd 24-h. Conclusions: Different statistical tests yielded very different conclusions to reproducibility of ABPM. Clinicians and researchers should be aware of the degree of agreement of ABPM.

A Multiscale Approach to Investigate the Biosemiotic Complexity of Two Acoustic Communities in Primary Forests with High Ecosystem Integrity Recorded with 3D Sound Technologies

The biosemiotic complexity of acoustic communities in the primary forests of Ulu Temburong (Brunei, Borneo) and Yasuni (Ecuador, Amazon) was investigated with continuous 24-h recordings, using the acoustic signature and multiscale approach of ecoacoustic events and their emergent fractal dimensions. The 3D recordings used for the analysis were collected in undisturbed primary equatorial forests under the scope of the project, Fragments of Extinction, which produces 3D sound portraits with the highest definition possible using current technologies – a perfect dataset on which to perform a multiscale qualitative analysis. The ecoacoustic events (EEs) detected by a combination of the Acoustic Complexity Indices, ACIft, ACIft evenness, and ACItf evenness, and its fractal dimension were developed according to a biosemiotics approach in which the ecofield theory states that EE functions like a species-specific carrier of meaning. EEs, extracted according to 10 levels of temporal resolution, from 1 to 360 s, confirm the hypothesis that these acoustic communities have an internal complexity that responds to a fractal structure (fractal dimension D of Ulu Temburong D = 1.33 versus Yasuni D = 1.31). Yasuni was richer in EEs, with a higher coefficient of variation of hourly fractal dimension (Yasuni: D = 6.16 versus Ulu Temburong: D = 2.66). This methodology opens up promising new perspectives in the acoustic assessment of habitat quality and monitoring landscape modification. It also confirms the great potential of the biosemiotics approach in converting acoustic frequencies into ecoacoustic events through encoding procedures that mimic potential species-specific interpretations of the sonic environment.

Information-Domain Analysis of Cardiovascular Complexity: Night and Day Modulations of Entropy and the Effects of Hypertension.

Multiscale entropy (MSE) provides information-domain measures of the systems’ complexity. The increasing interest in MSE of the cardiovascular system lies in the possibility of detecting interactions with other regulatory systems, as higher neural networks. However, most of the MSE studies considered the heart-rate (HR) series only and a limited number of scales: actually, an integrated approach investigating HR and blood-pressure (BP) entropies and cross-entropy over the range of scales of traditional spectral analyses is missing. Therefore, we aim to highlight influences of higher brain centers and of the autonomic control on multiscale entropy and cross-entropy of HR and BP over a broad range of scales, by comparing different behavioral states over 24 h and by evaluating the influence of hypertension, which reduces the autonomic control of BP. From 24-h BP recordings in eight normotensive and eight hypertensive participants, we selected subperiods during daytime activities and nighttime sleep. In each subperiod, we derived a series of 16,384 consecutive beats for systolic BP (SBP), diastolic BP (DBP), and pulse interval (PI). We applied a modified MSE method to obtain robust estimates up to time scales of 334 s, covering the traditional frequency bands of spectral analysis, for three embedding dimensions and compared groups (rank-sum test) and conditions (signed-rank test) at each scale. Results demonstrated night-and-day differences at scales associable with modulations in vagal activity, in respiratory mechanics, and in local vascular regulation, and reduced SBP-PI cross-entropy in hypertension, possibly representing a loss of complexity due to an impaired baroreflex sensitivity.

Housing tiestall dairy cows in deep-bedded pens during an 8-week dry period: Effects on lying time, lying postures, and rising and lying-down behaviors

Dairy cow lying behavior is useful in determining the cow's level of welfare, as well as in determining how her environment may affect her comfort and ease of movement. In tiestall systems, cows usually remain in a stall for the duration of their lactation. The dry period offers a unique opportunity to provide alternative housing to the cow with minimal effects on farm housing and management. Our objective was to determine whether housing tiestall cows in deep-bedded pens over an 8-wk dry period altered lying time, lying and rising ability, or lying postures. At dry-off, 20 cows, paired by parity and calving date, were randomly assigned to a deep-bedded loose pen (LP) or a tiestall (TS). Leg-mounted pedometers measured lying time. Rising and lying ability were measured using 6 events of rising and lying from 24-h video recordings taken once a week per cow. Sequenced images (1/min) from the 24-h recordings were used to document lying postures and locations for each cow. Data were analyzed for the early (first week of dry-off), mid, and late (week before calving) terms of the dry period. Lying time did not differ between LP and TS but was numerically higher for LP than TS cows (14.4 vs. 13.0 h/d, respectively). Contact with stall or pen confines when lying down was 5 times higher in TS than LP. The increased contact, coupled with a higher occurrence of hindquarter shifting in the late term, led to higher overall abnormal lying behaviors in TS. Contact with the stall upon rising increased in the late term for TS cows. Cows housed in loose pens also exhibited greater variation in hind-leg postures, keeping legs tucked 20% less often in favor of alternative postures. Stall hardware (e.g., tie rail, dividers) may have affected the ease of transition between lying and standing, leading to higher levels of contact with the stall. Loose-pen cows are able to assume more postures than TS cows when provided more space, possibly allowing them to orient themselves in ways that provide greater comfort. Lying surface in the deep-bedded loose pen may ease the cow's lying-down and rising movements and lead to the higher lying time found with LP cows. Overall, aspects of the stall largely contributed to differences in lying behaviors, warranting further study into whether freestall systems would yield similar outcomes. Improving our concept of ease of movement related to lying and quality of rest in dairy cows, through evaluating lying behaviors in different housing systems, allows for better recommendations on viable alternative housing options.

Ambulatory ECG predictors of atrial fibrillation are ineffective in severe sleep apnea

BackgroundObstructive sleep apnea (OSA) is strongly associated with atrial fibrillation (AF). Long-term ECG monitoring with implantable loop recorders facilitates the identification of undiagnosed AF in 20% of severe OSA cases. However, ambulatory ECG (AECG) monitoring is less resource intensive, and various parameters have been shown to predict AF. The aim of this study was to assess the efficacy of such AECG-based AF predictors in identifying patients with severe OSA most at risk. MethodsProspective observational study including patients with severe OSA and no history of AF. Patients had two 24-h AECG recordings, and if no AF was detected, implanted with a loop recorder (maximum 3 years). ResultsOf 25 patients implanted, AF ≥ 10 s was detected in 5 patients. None of the parameters from the AECG recordings were significantly different between patients who did and did not develop AF. ConclusionsAECG-based parameters were not effective for the prediction of AF in this severe OSA cohort.

Improvement in the quality of life of patients with persistent or long-standing persistent atrial fibrillation after hybrid ablation.

Hybrid ablation (i.e., a combination of a thoracoscopic surgical ablation followed by a catheter ablation) is a treatment option for patients with non-paroxysmal atrial fibrillation (AF). Despite its promising efficacy, it is a surgical procedure with a relatively high risk of complications that could affect the quality of life (QoL) of patients, even when sinus rhythm is restored. To describe changes in the QoL of patients with non-paroxysmal AF before and after a hybrid ablation. Patients after hybrid ablation for persistent or long-standing persistent AF were prospectively studied. Follow-up visits were scheduled at 1, 3, 6, 9, and 12months. The maintenance of SR was assessed using 1-week Holter recordings at 6 and 12months and 24-h Holter recordings at 3 and 9months, or via an implantable loop recorder. QoL was assessed using the Atrial Fibrillation Effect on Quality-of-life (AFEQT) and the EuroQoL-5Dimensions (EQ-5D) questionnaires before and 12months after ablation. Seventy-five patients (49 men, age 62.9 ± 8.45years, 48 (64%) with long-standing persistent AF) were enrolled. Fifty-two (69.3%, SR group) were AF-free during the 12-month follow-up, 16 (21.3%, PAROX group) had only paroxysms of AF after ablation, and 7 (9.3%, PERM group) were on rate control due to permanent AF reoccurrence. The AFEQT score increased significantly in the SR group from 59.9 ± 19.4 to 91.4 ± 10.8 (p < 0.001), and in the PAROX group from 58.8 ± 19.0 to 81.5 ± 14.1 (p = 0.002) but remained unchanged in the PERM group (44.6 ± 7.5 vs. 47.4 ± 5.5, p = 0.24). The EQ-5D score significantly decreased in the descriptive part (from 7.90 ± 2.61 to 6.64 ± 1.90, p = 0.0001) and increased on the visual analog scale (from 63.56 ± 19.11 to 79.30 ± 16.9, p < 0.0001) in the SR group. In the PAROX group, no significant change was present on either the descriptive part (p = 0.3) or in the visual analog scale (p = 0.48). Similarly, no significant changes were present on either the descriptive part (p = 0.93) or the visual analog scale (p = 0.4) in the PERM group. The QoL of patients with non-paroxysmal AF and patients with AF paroxysms, after successful hybrid ablation, improved significantly in patients with SR. No significant improvement was present in patients on rate control after an unsuccessful ablation.

Exercise Frequency Determines Heart Rate Variability Gains in Older People: A Meta-Analysis and Meta-Regression.

Previous studies have suggested that exercise training improves cardiac autonomic drive in young and middle-aged adults. In this study, we discuss the benefits for the elderly. We aimed to establish whether exercise still increases heart rate variability (HRV) beyond the age of 60years, and to identify which training factors influence HRV gains in this population. Interventional controlled and non-controlled studies were selected from the PubMed, Ovid, Cochrane and Google Scholar databases. Only interventional endurance training protocols involving healthy subjects aged 60years and over, and measuring at least one heart rate global or parasympathetic index, such as the standard deviation of the normal-to-normal intervals (SDNN), total frequency power (Ptot), root mean square of successive differences between adjacent NN intervals (RMSSD), or high frequency power (HF) before and after the training intervention, were included. HRV parameters were pooled separately from short-term and 24h recordings for analysis. Risks of bias were assessed using the Methodological Index for Non-Randomized Studies and the Cochrane risk of bias tool. A random-effects model was used to determine effect sizes (Hedges' g) for changes, and heterogeneity was assessed using Q and I statistics. Twelve studies, seven of which included a control group, including 218 and 111 subjects, respectively (mean age 69.0 ± 3.2 and 68.6 ± 2.5), were selected for meta-analysis. Including the 12 studies demonstrated homogeneous significant effect sizes for short-term (ST)-SDNN and 24h-SDNN, with effect sizes of 0.366 (95% CI 0.185-547) and 0.442 (95% CI 0.144-0.740), respectively. Controlled study analysis demonstrated homogeneous significant effect sizes for 24h-SDNN with g = 0.721 (95% CI 0.184-1.257), and 24h-Ptot with g = 0.731 (95% CI 0.195-1.267). Meta-regression analyses revealed positive relationships between ST-SDNN effect sizes and training frequency ([Formula: see text] = 0.000; [Formula: see text] = 0.000; p = 0.0462). This meta-analysis demonstrates a positive effect of endurance-type exercise on autonomic regulation in older adults. However, the selected studies expressed some risks of bias. We conclude that chronic endurance exercise leads to HRV improvements in a linear frequency-response relationship, encouraging the promotion of high-frequency training programmes in older adults.

Intermittent hypoxia in preterm infants: Measurement using the desaturation index.

The aims of this study were to: (i) Determine in preterm infants at neonatal discharge the prevalence of intermittent hypoxia (IH), as measured by the oxygen desaturation index (DSI) recorded by pulse oximetry and (ii) Determine the change in values for very preterm infants at 1-month post discharge. Preterm infants were recruited from the Wellington regional neonatal intensive care unit (NICU) and 24-h pulse oximetry recordings performed immediately before discharge. Infants born <32 weeks gestational age (GA) had repeat oximetry 1-month post discharge. Oxygenation measures included the 3% and 4% desaturation (DSI 3%, DSI 4%) indices. At discharge from the neonatal unit the median and interquartile range (IQR) for DSI 4% was 51 (31-74) events per hour with normal mean SpO2 (median of 97.9% [97.2-98.8 IQR]). Episodes of IH 1 month post discharge decreased with improvements of between 42% and 57% seen for the three DSI measures. Infants <32 weeks GA had higher median DSI 3 and 4% values at discharge but differences when compared with late preterm infants were not significant. Preterm infants have frequent episodes of IH as measured by the 3% and 4% DSI when deemed otherwise ready for discharge home. Further research in a larger cohort of very preterm infants and also in term infants is needed to determine the significance of this finding.

A Fast DFA Algorithm for Multifractal Multiscale Analysis of Physiological Time Series.

Detrended fluctuation analysis (DFA) is a popular tool in physiological and medical studies for estimating the self-similarity coefficient, α, of time series. Recent researches extended its use for evaluating multifractality (where α is a function of the multifractal parameter q) at different scales n. In this way, the multifractal-multiscale DFA provides a bidimensional surface α(q,n) to quantify the level of multifractality at each scale separately. We recently showed that scale resolution and estimation variability of α(q,n) can be improved at each scale n by splitting the series into maximally overlapped blocks. This, however, increases the computational load making DFA estimations unfeasible in most applications. Our aim is to provide a DFA algorithm sufficiently fast to evaluate the multifractal DFA with maximally overlapped blocks even on long time series, as usually recorded in physiological or clinical settings, therefore improving the quality of the α(q,n) estimate. For this aim, we revise the analytic formulas for multifractal DFA with first- and second-order detrending polynomials (i.e., DFA1 and DFA2) and propose a faster algorithm than the currently available codes. Applying it on synthesized fractal/multifractal series we demonstrate its numerical stability and a computational time about 1% that required by traditional codes. Analyzing long physiological signals (heart-rate tachograms from a 24-h Holter recording and electroencephalographic traces from a sleep study), we illustrate its capability to provide high-resolution α(q,n) surfaces that better describe the multifractal/multiscale properties of time series in physiology. The proposed fast algorithm might, therefore, make it easier deriving richer information on the complex dynamics of clinical signals, possibly improving risk stratification or the assessment of medical interventions and rehabilitation protocols.

Sudden Cardiac Death in Dialysis: Arrhythmic Mechanisms and the Value of Non-invasive Electrophysiology.

Sudden Cardiac Death (SCD) is the leading cause of cardiovascular death in dialysis patients. This review discusses potential underlying arrhythmic mechanisms of SCD in the dialysis population. It examines recent evidence from studies using implantable loop recorders and from electrophysiological studies in experimental animal models of chronic kidney disease. The review summarizes advances in the field of non-invasive electrophysiology for risk prediction in dialysis patients focusing on the predictive value of the QRS-T angle and of the assessments of autonomic imbalance by means of heart rate variability analysis. Future research directions in non-invasive electrophysiology are identified to advance the understanding of the arrhythmic mechanisms. A suggestion is made of incorporation of non-invasive electrophysiology procedures into clinical practice.Key Concepts:– Large prospective studies in dialysis patients with continuous ECG monitoring are required to clarify the underlying arrhythmic mechanisms of SCD in dialysis patients.– Obstructive sleep apnoea may be associated with brady-arrhythmias in dialysis patients. Studies are needed to elucidate the burden and impact of sleeping disorders on arrhythmic complications in dialysis patients.– The QRS-T angle has the potential to be used as a descriptor of uremic cardiomyopathy.– The QRS-T angle can be calculated from routine collected surface ECGs. Multicenter collaboration is required to establish best methodological approach and normal values.– Heart Rate Variability provides indirect assessment of cardiac modulation that may be relevant for cardiac risk prediction in dialysis patients. Short-term recordings with autonomic provocations are likely to overcome the limitations of out of hospital 24-h recordings and should be prospectively assessed.

Sound recordings of Apis cerana japonica colonies over 24 h reveal unique daily hissing patterns

The simultaneous wing movement by multiple worker bees in a colony produces a hissing sound, which is a novel acoustic and vibrational signal of the honey bees. Hissing of honey bees is thought to be a response to direct, threatening stimuli. However, we discovered Japanese honey bees (Apis cerana japonica) can hiss even without obvious disturbances in previous study. In this study, to understand the temporal characteristics of honey bee hissing, we conducted 24-h sound recordings over 7 months in 2015 and investigated when A. cerana japonica hissed every day. Additionally, we also investigated the relationship of hissing onset and offset times with sunrise and sunset times, and environmental factors. We found that honey bees hiss daily during daytime and most frequently at dawn, with hissing onset/offset occurring mostly within 30 min of sunrise/sunset time. Hissing onset and offset were significantly related to sunrise and sunset times, respectively, and also to solar radiation intensity. The findings reveal that A. cerana japonica hissing has unique temporal patterns, and also shed a new light on vibrational collective behavior in honey bees.

A Novel Wearable Device for Continuous Ambulatory ECG Recording: Proof of Concept and Assessment of Signal Quality

Diagnosis of arrhythmic disorders is challenging because of their short-lasting, intermittent character. Conventional technologies of noninvasive ambulatory rhythm monitoring are limited by modest sensitivity. We present a novel form of wearable electrocardiogram (ECG) sensors providing an alternative tool for long-term rhythm monitoring with the potential of increased sensitivity to detect intermittent or subclinical arrhythmia. The objective was to assess the signal quality and R-R coverage of a wearable ECG sensor system compared to a standard 3-lead Holter. In this phase-1 trial, healthy individuals underwent 24-h simultaneous rhythm monitoring using the OMsignal system together with a 3-lead Holter recording. The OMsignal system consists of a garment (bra or shirt) with integrated sensors recording a single-lead ECG and an acquisition module for data storage and processing. Head-to-head signal quality was assessed regarding adequate P-QRS-T distinction and was performed by three electrophysiologists blinded to the recording technology. The accuracy of signal coverage was assessed using Bland-Altman analysis. Fifteen individuals underwent simultaneous 24-h recording. Signal quality and accuracy of the OMgaments was equivalent to Holter-monitoring (84% vs. 93% electrophysiologists rating, p = 0.06). Signal coverage of R-R intervals showed a very close overlay between the OMsignal system and Holter signals, mean difference in heart rate of 2 ± 5 bpm. The noise level of OMgarments was comparable to Holter recording. OMgarments provide high signal quality for adequate rhythm analysis, representing a promising novel technology for long-term non-invasive ECG monitoring.

Ambient air pollution is associated with cardiac repolarization abnormalities in healthy adults

BackgroundAmbient air pollution has been associated with acute cardiovascular events; however, the underlying mechanisms remain incompletely understood. We aimed to examine the impacts of ambient air pollutants on cardiac ventricular repolarization in a highly polluted urban region. MethodsSeventy-three healthy non-smoking young adults (66% female, mean age of 23.3 ± 5.4 years) were followed with four repeated 24-h electrocardiogram recordings in 2014–2016 in Beijing, China. Continuous concentrations of ambient particulates in size fractions of 5–560 nm diameter, black carbon (BC), nitrogen dioxide (NO2), carbon monoxide (CO), sulfur dioxide (SO2), and ozone (O3) were measured at a fixed-location air pollution monitoring station. Generalized linear mixed models, with adjustment for individual risk factors, time-varying factors and meteorological parameters, were used to evaluate the effects of air pollution on 5-min segments of heart rate-corrected QT interval (QTc), an index of cardiac ventricular repolarization. ResultsDuring the study period, the mean levels of number concentrations of particulates in size range of 5–560 nm (PNC5–560) were 20,711 particles/cm3. Significant increases in QTc of 0.56% (95% CI: 0.27, 0.84) to 1.76% (95% CI: 0.73, 2.79) were associated with interquartile range increases in PNC50–560 at prior 1–5 moving average days. Significant increases in QTc were also associated with increases in exposures to traffic-related air pollutants (BC, NO2 and CO), a combustion pollutant SO2, and the secondary pollutant O3. The associations were stronger in participants who were male, overweight, with abdominal obesity, and with higher levels of high-sensitivity C-reactive protein. ConclusionsOur findings suggest that exposures to higher levels of ambient particulates in small size fractions and traffic pollutants were associated with cardiac repolarization abnormalities in healthy adults, and the cardio-metabolic risks may modify the adverse cardiac effects attributable to air pollution.

Диагностические возможности фрагментарного мониторирования электрокардиограммы у пациентов с сердечными аритмиями

The data about the use of external ECG event recorders are few and contradictory, which makes it relevant to the present study. We evaluated the clinical efficacy of fragmentary ECG monitoring in patients with palpitation and/or dizziness. The study involved 83 patients, mean age 46,5±13,6 years, with complaints of palpitation (group 1, n=65) and dizziness/syncope (group 2, n=18). All patients underwent 24-h holter monitoring and event recording. Comparative analysis showed that the diagnostic value of event recording was higher: 50,6% versus 24.1%. Therefore, the fragmentary ECG monitoring is an effective method to detect arrhythmic events and its diagnostic value 2 times higher than the traditional Holter monitoring.