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Introduction: Ventricular arrhythmia is commonly provoked by acute cardiac ischemia through sympathetic exaggeration and is often resistant to anti-arrhythmic therapies. Thoracic epidural anesthesia has been reported to terminate fatal ventricular arrhythmia; however, its underlying mechanism is unknown. Methods: Rats were randomly divided into four groups: sham, sham plus bupivacaine, ischemia/reperfusion (IR), and IR plus bupivacaine groups. Bupivacaine (1 mg/mL, 0.05 mL/100 g body weight) was injected intrathecally into the L5–L6 intervertebral space prior to establishing a myocardial IR rat model. Thereafter, cardiac arrhythmia, cardiac function, myocardial injury, and electrical activities of the heart and spinal cord were evaluated. Results: Intrathecal bupivacaine inhibited spinal neural activity, improved heart rate variability, reduced ventricular arrhythmia score, and ameliorated cardiac dysfunction in IR rats. Furthermore, intrathecal bupivacaine attenuated cardiac injury and myocardial apoptosis and regulated cardiomyocyte autophagy and connexin-43 distribution during myocardial IR. Conclusion: Our results indicate that intrathecal bupivacaine blunts spinal neural activity to prevent cardiac arrhythmia and dysfunction induced by IR and that this anti-arrhythmic activity may be associated with regulation of autonomic balance, myocardial apoptosis and autophagy, and cardiac gap junction function. [ABSTRACT FROM AUTHOR]

Atrial fibrillation (AF) is a rarely reported arrhythmia in otherwise healthy newborn foals, with a single case of cardioversion using procainamide administration described in the literature. Two neonatal Thoroughbred colts were presented to an equine hospital because of an irregularly irregular tachyarrhythmia and poor latching when trying to nurse. History, physical examination, and initial diagnostic testing including ECG and echocardiography confirmed AF without structural heart disease. The 1st foal converted into normal sinus rhythm after treatment with IV metoprolol and quinidine. The 2nd foal converted to normal sinus rhythm after a single IV dose of metoprolol, intended for rate control. Demeanor and nursing behavior improved markedly after conversion. The 2 foals had normal heart rates and sinus rhythm that persisted for 6 weeks until euthanasia in the 1st foal and for 2 years in the 2nd foal. Rate control and cardioversion should be considered as a treatment for persistent lone AF in neonatal foals. [ABSTRACT FROM AUTHOR]

Background: A relatively common complication of COVID -19 infection is arrhythmia. There is limited information about myocardial deformation and heart rate variability (HRV) in symptomatic post COVID patients presented by ventricular arrhythmia. Aim of the study: Our goal was to assess 2D-ventricular strain and heart rate variability indices (evaluated by ambulatory ECG monitoring) in post-COVID-19 patients suffering from ventricular arrhythmia. Methods: The current observational case–control study performed on 60 patients one month after they had recovered from the COVID-19 infection. Thirty healthy volunteers served as the control group. Each participant had a full medical history review, blood tests, a 12-lead surface electrocardiogram (ECG), 24-h ambulatory ECG monitoring, and an echo-Doppler examination to evaluate the left ventricular (LV) dimensions, tissue Doppler velocities, and 2D-speckle tracking echocardiography (2D-STE) for both the LV and right ventricular (RV) strain. Results: Symptomatic post-COVID patients with monomorphic premature ventricular contractions (PVCs) showed a substantial impairment of LV/RV systolic and diastolic functions, LV/RV myocardial performance (MPI) with reduced indices of HRV. Patients with higher versus lower ventricular burden had poorer functional status, higher levels of inflammatory biomarkers and reduced parameters of HRV (New York Heart Association (NYHA) class: 2.1 ± 0.9 vs. 1.5 ± 0.6, p < 0.001, C-reactive protein (CRP): 13.3 ± 4.1 vs. 8.3 ± 5.9 mg/L, p < 0.0001, low frequency/high frequency (LF/HF): 3.6 ± 2.4 vs. 2.2 ± 1.2, p < 0.002, the root mean square of the difference between successive normal intervals (rMSSD): 21.8 ± 4.7 vs. 29.3 ± 14.9 ms, p < 0.039 and the standard deviation of the RR interval (SDNN): 69.8 ± 19.1 vs.108.8 ± 37.4 ms, p < 0.0001). The ventricular burden positively correlated with neutrophil/lymphocyte ratio (NLR) (r = 0.33, p < 0.001), CRP (r = 0.60, p < 0.0001), while it negatively correlated with LV-global longitudinal strain (GLS) (r = -0.38, p < 0.0001), and RV-GLS (r = -0.37, p < 0.0001). Conclusions: Patients with post-COVID symptoms presented by ventricular arrhythmia had poor functional status. Patients with post-COVID symptoms and ventricular arrhythmia had subclinical myocardial damage, evidenced by speckle tracking echocardiography while having apparently preserved LV systolic function. The burden of ventricular arrhythmia in post-COVID patients significantly correlated with increased inflammatory biomarkers and reduced biventricular strain. [ABSTRACT FROM AUTHOR]

According to the World Health Organization (WHO), cardiovascular illnesses, including arrhythmia, are the primary cause of mortality globally, responsible for over 31% of all fatalities each year. To reduce mortality, early and precise diagnosis is essential. Although the analysis of electrocardiograms (ECGs) is the primary means of detecting arrhythmias, it depends significantly on the expertise and subjectivity of the health professional reading and interpreting the ECG, and errors may occur in detection. Artificial intelligence provides tools, techniques, and models that can support health professionals in detecting arrhythmias. However, these tools are based only on ECG data, of which the process of obtaining is an invasive, high-cost method requiring specialized equipment and personnel. Smartwatches feature sensors that can record real-time signals indicating the heart's behavior, such as ECG signals and heart rate. Using this approach, we propose a machine learning- and deep learning-based approach for detecting arrhythmias using heart rate data obtained with smartwatches. Heart rate data were collected from 252 patients with and without arrhythmias who attended a clinic in Arequipa, Peru. Heart rates were also collected from 25 patients who wore smartwatches. Ten machine learning algorithms were implemented to generate the most effective arrhythmia recognition model, with the decision tree algorithm being the most suitable. The results were analyzed using accuracy, sensitivity, and specificity metrics. Using Holter data yielded values of 93.2%, 91.89%, and 94.59%, respectively. Using smartwatch data yielded values of 70.83%, 91.67%, and 50%, respectively. These results indicate that our model can effectively recognize arrhythmias from heart rate data. The high sensitivity score suggests that our model adequately recognizes true positives; that is, patients with arrhythmia. Likewise, its specificity suggests an adequate recognition of false positives. [ABSTRACT FROM AUTHOR]

This article discusses three cases of post-surgical spontaneous paroxysmal hypothermia (SPH), a condition characterized by recurrent episodes of hypothermia and mental confusion related to a hypothalamic lesion. The cases involve patients who underwent surgery for various hypothalamus disorders and experienced episodes of hypothermia, bradycardia, and other symptoms. The article highlights the importance of prompt diagnosis and appropriate interventions for effective treatment of SPH. It also suggests that changes in sympatho-vagal balance may play a role in the cardiac consequences of SPH. [Extracted from the article]

Although the treadmill and cycle ergometer are commonly used for exercise stress electrocardiography (ECG) testing, they are often difficult to perform with children. We herein evaluated the utility and safety of the 2-minute jump test (2MJT) as a simple, alternative exercise test. One hundred patients, including 60 male patients, with an average age at study commencement of 10.7±3.5 years (mean±standard deviation) and with no exercise restriction who underwent a cardiac check-up between November 2020 and March 2022 at the study center were included. After recording their resting ECG, they jumped for 2 minutes during ECG recording, and the change in heart rate (HR), ECG findings, and occurrence of adverse events were investigated. As a result, patients jumped 185±60 times in two minutes, and their HR increased from 76±13 beats/min at rest to 172±18 beats/min at peak during the test. Ninety (90%) patients attained the ideal target HR of > 150 beats/minute. During the recovery period after loading, five patients had abnormal ECG findings (ventricular extrasystoles, second-degree atrioventricular block, and atrial extrasystoles in two, two, and one patient, respectively) but completely resolved spontaneously within three minutes. Our findings suggested that the 2MJT is a useful and safe exercise test capable of inducing sufficient increase in HR in a short time in children. [ABSTRACT FROM AUTHOR]

Williams–Beuren syndrome (WBS) is a rare genetic condition caused by a chromosomal microdeletion at 7q11.23. It is a multisystem disorder characterized by distinct facies, intellectual disability, and supravalvar aortic stenosis (SVAS). Those with WBS are at increased risk of sudden death, but mechanisms underlying this remain poorly understood. We recently demonstrated autonomic abnormalities in those with WBS that are associated with increased susceptibility to arrhythmia and sudden cardiac death (SCD). A recently introduced method for heart rate variability (HRV) analysis called "heart rate fragmentation" (HRF) correlates with adverse cardiovascular events (CVEs) and death in studies where heart rate variability (HRV) failed to identify high-risk subjects. Some argue that HRF quantifies nonautonomic cardiovascular modulators. We, therefore, sought to apply HRF analysis to a WBS cohort to determine 1) if those with WBS show differences in HRF compared with healthy controls and 2) if HRF helps characterize HRV abnormalities in those with WBS. Similar to studies of those with coronary artery disease (CAD) and atherosclerosis, we found significantly higher HRF (4 out of 7 metrics) in those with WBS compared with healthy controls. Multivariable analyses showed a weak-to-moderate association between HRF and HRV, suggesting that HRF may reflect HRV characteristics not fully captured by traditional HRV metrics (autonomic markers). We also introduce a new metric inspired by HRF methodology, significant acute rate drop (SARD), which may detect vagal activity more directly. HRF and SARD may improve on traditional HRV measures to identify those at greatest risk for SCD both in those with WBS and in other populations. NEW & NOTEWORTHY: This work is the first to apply heart rate fragmentation analyses to individuals with Williams syndrome and posits that the heart rate fragmentation parameter W3 may enable detection and investigation of phenomena underlying the proarrhythmic short-long-short RR interval sequences paradigm known to precede ventricular fibrillation and ventricular tachycardia. It also forwards a novel method for quantifying sinus arrhythmia and sinus pauses that likely correlate with parasympathetic activity. [ABSTRACT FROM AUTHOR]

Introduction Methods Results Conclusion Early‐onset atrial fibrillation (AF) has already been observed in approximately 2% of patients with genetically proven long QT syndrome (LQTS). This frequency is higher than population‐based estimates of early‐onset AF. However, the concomitant expression of AF in LQTS is likely underestimated. The purpose of this study was to examine the clinical presentation, genetic background, and outcomes of a cohort of patients with LQTS and early‐onset AF referred to a single tertiary center.Twenty‐seven patients diagnosed with congenital LQTS were included in the study based on the documentation of early‐onset (age ≤50 years) clinical or subclinical AF episodes in all available medical records, including standard electrocardiograms, wearable monitor or cardiac implantable electronic devices.Seventeen patients experienced clinical AF during the follow‐up period. Subclinical AF was detected in 10 patients through insertable or wearable cardiac monitors. In our series, the mean heart rate during AF episodes was found to be relatively low despite the patients' young age and the low or minimal effective doses of beta‐blockers used for QTc interval control. All patients exhibiting LQTS and early‐onset AF were genotype positive, carrying mutations in the KCNQ1 (66%), KCNH2, KCNE1, and SCN5A genes. Notably, most of these patients carried the same p.(R231C) mutation in the KCNQ1 gene (59%) and were from the same families, suggesting concurrent expression of familial AF and LQTS.LQTS patients are prone to developing clinical and subclinical AF, even at a younger age. The occurrence of early‐onset AF in the LQTS population could be more frequent than previously assumed. AF should be considered as a potential dysrhythmia related to LQTS. Our study emphasizes the importance of carefully researching clinical and/or subclinical episodes of AF through strict heart rhythm monitoring in the LQTS population. [ABSTRACT FROM AUTHOR]

Introduction: Ventricular unloading during prolonged bed rest, mechanical circulatory support or microgravity has repeatedly been linked to potentially life-threatening arrhythmias. It is unresolved, whether this arrhythmic phenotype is caused by the reduction in cardiac workload or rather by underlying diseases or external stimuli. We hypothesized that the reduction in cardiac workload alone is sufficient to impair ventricular repolarization and to induce arrhythmias in hearts. Methods: Rat hearts were unloaded using the heterotopic heart transplantation. The ECG of unloaded and of control hearts were telemetrically recorded over 56 days resulting in >5 × 106 cardiac cycles in each heart. Long-term electrical remodeling was analyzed using a novel semi-automatic arrhythmia detection algorithm. Results: 56 days of unloading reduced left ventricular weight by approximately 50%. While unloading did not affect average HRs, it markedly prolonged the QT interval by approximately 66% and induced a median tenfold increase in the incidence of ventricular arrhythmias in comparison to control hearts. Conclusion: The current study provides direct evidence that the previously reported hypertrophic phenotype of repolarization during cardiac unloading translates into an impaired ventricular repolarization and ventricular arrhythmias in vivo. This supports the concept that the reduction in cardiac workload is a causal driver of the development of arrhythmias during ventricular unloading. [ABSTRACT FROM AUTHOR]

AbstractThe classification of inter-patient ECG data for arrhythmia detection using electrocardiogram (ECG) signals presents a significant challenge. Despite the recent surge in deep learning approaches, there remains a noticeable gap in the performance of inter-patient ECG classification. In this study, we introduce an innovative approach for ECG classification in arrhythmia detection by employing a 1D convolutional neural network (CNN) to leverage both morphological and temporal characteristics of cardiac cycles. Through the utilization of 1D-CNN layers, we automatically capture the morphological attributes of ECG data, allowing us to represent the shape of the ECG waveform around the R peaks. Additionally, we incorporate four RR interval features to provide temporal context, and we explore the potential application of entropy rate as a feature extraction technique for ECG signal classification. Consequently, the classification layers benefit from the combination of both temporal and learned features, leading to the achievement of the final arrhythmia classification. We validate our approach using the MIT-BIH arrhythmia dataset, employing both intra-patient and inter-patient paradigms for model training and testing. The model’s generalization ability is assessed by evaluating it on the INCART dataset. The model attains average accuracy rates of 99.13% and 99.17% for 2-fold and 5-fold cross-validation, respectively, in intra-patient classification with five classes. In inter-patient classification with three and five classes, the model achieves average accuracies of 98.73% and 97.91%, respectively. For the INCART dataset, the model achieves an average accuracy of 98.20% for three classes. The experimental outcomes demonstrate the superiority of the proposed model compared to state-of-the-art models in recognizing arrhythmias. Thus, the proposed model exhibits enhanced generalization and the potential to serve as an effective solution for recognizing arrhythmias in real-world datasets characterized by class imbalances in practical applications. [ABSTRACT FROM AUTHOR]

Background: The relationship between obstructive sleep apnea (OSA) and the occurrence of arrhythmias and heart rate variability (HRV) in hypertensive patients is not elucidated. Our study investigates the association between OSA, arrhythmias, and HRV in hypertensive patients. Methods: We conducted a cross-sectional analysis involving hypertensive patients divided based on their apnea-hypopnea index (AHI) into two groups: the AHI ≤ 15 and the AHI > 15. All participants underwent polysomnography (PSG), 24-hour dynamic electrocardiography (DCG), cardiac Doppler ultrasound, and other relevant evaluations. Results: The AHI > 15 group showed a significantly higher prevalence of frequent atrial premature beats and atrial tachycardia (P = 0.030 and P = 0.035, respectively) than the AHI ≤ 15 group. Time-domain analysis indicated that the standard deviation of normal-to-normal R-R intervals (SDNN) and the standard deviation of every 5-minute normal-to-normal R-R intervals (SDANN) were significantly higher in the AHI > 15 group (P = 0.020 and P = 0.033, respectively). Frequency domain analysis revealed that the low-frequency (LF), high-frequency (HF) components, and the LF/HF ratio were also significantly elevated in the AHI > 15 group (P < 0.001, P = 0.031, and P = 0.028, respectively). Furthermore, left atrial diameter (LAD) was significantly larger in the AHI > 15 group (P < 0.001). Both univariate and multivariable linear regression analyses confirmed a significant association between PSG-derived independent variables and the dependent HRV parameters SDNN, LF, and LF/HF ratio (F = 8.929, P < 0.001; F = 14.832, P < 0.001; F = 5.917, P = 0.016, respectively). Conclusions: Hypertensive patients with AHI > 15 are at an increased risk for atrial arrhythmias and left atrial dilation, with HRV significantly correlating with OSA severity. [ABSTRACT FROM AUTHOR]

Introduction: The accuracy of surface ECG algorithms for predicting the origin of outflow tract ventricular arrhythmias (OT‐VAs) might be questioned. Intracardiac electrograms recorded at anatomic landmarks could provide new predictive insights. We aim to evaluate the efficacy of a novel criterion utilizing the activation pattern of the coronary sinus (CS) in localizing OT‐VAs, including VAs originating from the right ventricular outflow tract (RVOT), endocardial left ventricular outflow tract (Endo‐LVOT), and epicardial left ventricular outflow tract (Epi‐LVOT). Methods: We measured the ventricular activation time of the mitral annulus (MA) from the onset of the earliest QRS complex of VAs to the initial deflection over the isoelectric line at local signals, namely the QRS‐MA interval. The activation at 3 and 12 o'clock of the MA was recorded as the QRS‐MA3 and QRS‐MA12 intervals, respectively. Their predictive values were compared to previous ECG algorithms. Results: A total of 68 patients with OT‐VAs were enrolled (51 for development and 17 for validation). From early to late, the ventricular activation sequences at MA12 were as follows: Epi‐LVOT, Endo‐LVOT, and RVOT. In LBBB morphology OT‐VAs, the QRS‐MA12 interval was significantly earlier for LVOT origins than RVOT origins. In the combined cohort of development and validation cohort, a cut‐off value of ≤10 ms predicted the LVOT origin with a sensitivity of 100% and specificity of 78%. The QRS‐MA12 interval ≤ −24 ms additionally predicted epicardial LVOT sites of origin. Conclusions: The QRS‐MA interval could accurately differentiate the OT‐VAs localization. [ABSTRACT FROM AUTHOR]

The article presents a case study of a 69-year-old female who underwent an electrophysiological study due to recurrent supraventricular tachycardia (SVT). It highlighted the occurrence of a wide complex tachycardia (WCT) and explored the mechanism behind its transformation following a premature ventricular complex (PVC). Treatment discussed involved radiofrequency ablation targeting the base of the triangle of Koch, which successfully eliminated SVT inducibility and potentially the NFV pathway.

Objectives: Living conditions play a major role in health and well-being, particularly for the cardiovascular and pulmonary systems. Depleted housing contributes to impairment and development of disease, but how it impacts body resiliency during exposure to environmental stressors is unknown. This study examined the effect of depleted (DH) versus enriched housing (EH) on cardiopulmonary function and subsequent responses to wildfire smoke. Materials and Methods: Two cohorts of healthy female mice, one of them surgically implanted with radiotelemeters for the measurement of electrocardiogram, body temperature (Tco) and activity, were housed in either DH or EH for 7 weeks. Telemetered mice were exposed for 1 h to filtered air (FA) and then flaming eucalyptus wildfire smoke (WS) while untelemetered mice, which were used for ventilatory assessment and tissue collection, were exposed to either FA or WS. Animals were continuously monitored for 5–7 days after exposure. Results: EH prevented a decrease in Tco after radiotelemetry surgery. EH mice also had significantly higher activity levels and lower heart rate during and after FA and WS. Moreover, EH caused a decreased number of cardiac arrhythmias during WS. WS caused ventilatory depression in DH mice but not EH mice. Housing enrichment also upregulated the expression of cardioprotective genes in the heart. Conclusions: The results of this study indicate that housing conditions impact overall health and cardiopulmonary function. More importantly, depleted housing appears to worsen the response to air pollution. Thus, non-chemical factors should be considered when assessing the susceptibility of populations, especially when it comes to extreme environmental events. [ABSTRACT FROM AUTHOR]

Background: Rate control (RC; meanHRHolter ≤ 125 bpm) increases survival in dogs with atrial fibrillation (AF). The mechanisms remain unclear. Hypothesis/Objectives: Investigate echocardiographic and biomarker differences between RC and non‐RC (NRC) dogs. Determine if changes post‐anti‐arrhythmic drugs (AAD) predict successful RC in subsequent Holter monitoring. Evaluate if early vs late RC affects survival. Animals: Fifty‐two dogs with AF. Methods: Holter‐derived mean heart rate, echocardiographic and biomarker variables from dogs receiving AAD were analyzed prospectively at each re‐evaluation and grouped into RC or NRC. The primary endpoint was successful RC. Between group comparisons of absolute values, magnitude of change from admission to re‐evaluations and end of study were performed using Mann‐Whitney tests or unpaired t‐tests. Logistic regression explored variables associated with inability to achieve RC at subsequent visits. Kaplan‐Meier survival analysis was used to compare survival time of early vs late RC. Results: At visit 2, 11/52 dogs were RC; at visit 3, 14/52 were RC; and at visit 4, 4/52 were RC. At the end of study, 25/52 remained NRC. At visit 2, both groups had increased cardiac dimensions, but NRC dogs had larger dimensions; biomarkers did not differ. At the end of study, RC showed decreased cardiac dimensions and end‐terminal pro‐brain natriuretic peptide (NT‐proBNP) compared with NRC. No variables were useful at predicting RC success in subsequent visits. Survival analysis found no differences between early vs late RC. Conclusions and Clinical Importance: The RC dogs had decreased cardiac dimensions and NT‐proBNP, suggesting HR‐mediated reverse‐remodeling might benefit survival, even with delayed RC achievement. Pursuit of RC is crucial despite initial failures. [ABSTRACT FROM AUTHOR]

Rhythmic feeding behavior is critical for regulating phase and amplitude in the ≈24-h variation of heart rate (RR intervals), ventricular repolarization (QT intervals), and core body temperature in mice. We hypothesized changes in cardiac electrophysiology associated with feeding behavior were secondary to changes in core body temperature. Telemetry was used to record electrocardiograms and core body temperature in mice during ad libitum-fed conditions and after inverting normal feeding behavior by restricting food access to the light cycle. Light cycle-restricted feeding modified the phase and amplitude of 24-h rhythms in RR and QT intervals, and core body temperature to realign with the new feeding time. Changes in core body temperature alone could not account for changes in phase and amplitude in the ≈24-h variation of the RR intervals. Heart rate variability analysis and inhibiting β-adrenergic and muscarinic receptors suggested that changes in the phase and amplitude of 24-h rhythms in RR intervals were secondary to changes in autonomic signaling. In contrast, changes in QT intervals closely mirrored changes in core body temperature. Studies at thermoneutrality confirmed that the daily variation in QT interval, but not RR interval, primarily reflected daily changes in core body temperature (even in ad libitum-fed conditions). Correcting the QT interval for differences in core body temperature helped unmask QT interval prolongation after starting light cycle-restricted feeding and in a mouse model of long QT syndrome. We conclude feeding behavior alters autonomic signaling and core body temperature to regulate phase and amplitude in RR and QT intervals, respectively. NEW & NOTEWORTHY: We used time-restricted feeding and thermoneutrality to demonstrate that different mechanisms regulate the 24-h rhythms in heart rate and ventricular repolarization. The daily rhythm in heart rate reflects changes in autonomic input, whereas daily rhythms in ventricular repolarization reflect changes in core body temperature. This novel finding has major implications for understanding 24-h rhythms in mouse cardiac electrophysiology, arrhythmia susceptibility in transgenic mouse models, and interpretability of cardiac electrophysiological data acquired in thermoneutrality. [ABSTRACT FROM AUTHOR]

This article discusses the use of machine learning to detect and predict atrial fibrillation (AF) using QT dynamicity. The study found that QT dynamicity can accurately predict the onset of AF episodes, providing valuable information for short-term prediction. The researchers used gradient-boosted decision trees as the machine learning technique and evaluated its performance using a database of Holter recordings. The article also references three other studies related to AF, which provide additional insights into the understanding and management of the condition. [Extracted from the article]

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S‐Limonene (s‐Lim) is a monocyclic monoterpene found in a variety of plants and has been shown to present antioxidant and cardioprotective activity in experimental models of myocardial infarction. The aim of this study was to evaluate the potential mechanism by which s‐Lim exerts its antiarrhythmic effect, focusing on the blockade of β‐adrenoceptor (β‐AR) and its effects on various in vivo and in vitro parameters, including electrocardiogram (ECG) measurements, left ventricular developed pressure (LVDP), the β‐adrenergic pathway, sarcomeric shortening and L‐type calcium current (ICa,L). In isolated hearts, 10 μM of s‐Lim did not alter the ECG profile or LVPD. s‐Lim increased the heart rate corrected QT interval (QTc) (10.8%) at 50 μM and reduced heart rate at the concentrations of 30 (12.4%) and 50 μM (16.6%). s‐Lim (10 μM) also inhibited the adrenergic response evoked by isoproterenol (ISO) (1 μM) reducing the increased of heart rate, LVDP and ECG changes. In ventricular cardiomyocyte, s‐Lim antagonized the effect of dobutamine by preventing the increase of sarcomeric shortening, demonstrating a similar effect to atenolol (blocker β1‐AR). In vivo, s‐Lim antagonized the effect of ISO (agonists β1‐AR), presenting a similar effect to propranolol (a non‐selective blocker β‐AR). In ventricular cardiomyocyte, s‐Lim did not alter the voltage dependence for ICa,L activation or the ICa,L density. In addition, s‐Lim did not affect changes in the ECG effect mediated by 5 μM forskolin (an activator of adenylate cyclase). In an in vivo caffeine/ISO‐induced arrhythmia model, s‐Lim (1 mg/kg) presented antiarrhythmic action verified by a reduced arrhythmia score, heart rate, and occurrence of ventricular premature beats and inappropriate sinus tachycardia. These findings indicate that the antiarrhythmic activity of s‐Lim is related to blockade of β‐AR in the heart. [ABSTRACT FROM AUTHOR]

Introduction Methods and Results Conclusion Pacemaker‐mediated tachycardia is a known arrhythmia in patients with dual chamber pacemakers and defibrillators and intact ventriculoatrial (VA) conduction. We report a case of pacemaker‐mediated reentrant arrhythmia (PMRA) in a patient with an atrioventricular (AV) synchronous leadless pacemaker.A 91‐year‐old female presented with 2:1 AV conduction and received an AV synchronous leadless pacemaker. She had atrial mechanical sense‐ventricular paced beats between heart rates of 80–100 bpm more than 80% of the time. She was found to have a new cardiomyopathy and was referred for placement of biventricular pacemaker. At the time of device implantation, her electrocardiogram showed ventricular pacing with a short RP interval and superiorly directed P waves. Changes in the ventricular pacing rate resulted in changes in the atrial rate. Following device placement, her heart rate decreased to the lower rate limit of her pacemaker. The atrial mechanical sense impulse most likely was generated by a retrograde conducted P wave resulting in near incessant PMRA.PMRA may occur in patients who receive an AV synchronous leadless pacemaker with intact VA conduction and sinoatrial node dysfunction. Due to the lower rates of PMRA, this arrhythmia may be underrecognized. Interventions for and implications of PMRA need further investigation. [ABSTRACT FROM AUTHOR]

Deep-space missions require preventative care methods based on predictive models for identifying in-space pathologies. Deploying such models requires flexible edge computing, which Open Neural Network Exchange (ONNX) formats enable by optimizing inference directly on wearable edge devices. This work demonstrates an innovative approach to point-of-care machine learning model pipelines by combining this capacity with an advanced self-optimizing training scheme to classify periods of Normal Sinus Rhythm (NSR), Atrial Fibrillation (AFIB), and Atrial Flutter (AFL). 742 h of electrocardiogram (ECG) recordings were pre-processed into 30-second normalized samples where variable mode decomposition purged muscle artifacts and instrumentation noise. Seventeen heart rate variability and morphological ECG features were extracted by convoluting peak detection with Gaussian distributions and delineating QRS complexes using discrete wavelet transforms. The decision tree classifier's features, parameters, and hyperparameters were self-optimized through stratified triple nested cross-validation ranked on F1-scoring against cardiologist labeling. The selected model achieved a macro F1-score of 0.899 with 0.993 for NSR, 0.938 for AFIB, and 0.767 for AFL. The most important features included median P-wave amplitudes, PRR20, and mean heart rates. The ONNX-translated pipeline took 9.2 s/sample. This combination of our self-optimizing scheme and deployment use case of ONNX demonstrated overall accurate operational tachycardia detection. [ABSTRACT FROM AUTHOR]

Arrhythmias frequently accompany heart failure and left ventricular dysfunction. Tachycardias, atrial fibrillation, and premature ventricular contractions can induce a reversible form of dilated cardiomyopathy (CM) known as arrhythmia-induced CM (AiCM). The intriguing question is why certain individuals are more susceptible to AiCM, despite similar arrhythmia burdens. The primary challenge is determining the extent of arrhythmias' contribution to left ventricular systolic dysfunction. AiCM should be considered in patients with a mean heart rate of >100 beats/min, atrial fibrillation, or a PVC burden of >10%. Confirmation of AiCM occurs when CM reverses upon eliminating the responsible arrhythmia. Therapy choice depends on the specific arrhythmia, patient comorbidities, and preferences. After left ventricular function is restored, ongoing follow-up is essential if an abnormal myocardial substrate persists. Accurate diagnosis and treatment of AiCM have the potential to enhance patients' quality of life, improve clinical outcomes, and reduce hospital admissions and overall health care costs. [Display omitted] • Tachycardia, AF, and PVCs can result in cardiomyopathy or AiCM. • Ambulatory ECG monitoring and CMR are key to establishing the diagnosis of AiCM. • Appropriate treatment of AiCM can reverse ventricular systolic dysfunction and potentially decrease morbidity and mortality. • A better understanding of the pathophysiological mechanisms and predictors of AiCM is needed to develop preventive strategies. [ABSTRACT FROM AUTHOR]

Background: Landiolol, a highly cardioselective agent with a short half-life (2.4–4 min), is commonly used as a perfusor or bolus application to treat tachycardic arrhythmia. Some small studies suggest that prior oral β-blocker use results in a less effective response to intravenous β-blockers. Methods: This study investigated whether prior chronic oral β-blocker (Lβ) or no prior chronic oral β-blocker (L–) intake influences the response to intravenous push-dose Landiolol in intensive care patients with acute tachycardic arrhythmia. Results: The effects in 30 patients (67 [55–72] years) were analyzed, 10 (33.3%) with and 20 (66.7%) without prior oral β-blocker therapy. Arrhythmias were diagnosed as tachycardic atrial fibrillation in 14 patients and regular, non-fluid-dependent, supraventricular tachycardia in 16 cases. Successful heart rate control (Lβ 4 vs. L– 7, p = 1.00) and rhythm control (Lβ 3 vs. L– 6, p = 1.00) did not significantly differ between the two groups. Both groups showed a significant decrease in heart rate when comparing before and after the bolus administration, without significant differences between the two groups (Lβ −26/min vs. L– −33/min, p = 0.528). Oral β-blocker therapy also did not influence the change in mean arterial blood pressure after Landiolol bolus administration (Lβ −5 mmHg vs. L– −4 mmHg, p = 0.761). Conclusions: A prior chronic intake of β-blockers neither affected the effectiveness of push-dose Landiolol in heart rate or rhythm control nor impacted the difference in heart rate or mean arterial blood pressure before and after the Landiolol boli. [ABSTRACT FROM AUTHOR]

Salmonid fish include some of the most valued cultured fish species worldwide. Unlike most other fish, the hearts of salmonids, including Atlantic salmon and rainbow trout, have a well-developed coronary circulation. Consequently, their hearts' reliance on oxygenation through coronary arteries leaves them prone to coronary lesions, believed to precipitate myocardial ischemia. Here, we mimicked such coronary lesions by subjecting groups of juvenile rainbow trout to coronary ligation, assessing histomorphological myocardial changes associated with ischemia and scarring in the context of cardiac arrhythmias using electrocardiography (ECG). Notable ECG changes resembling myocardial ischemia-like ECG in humans, such as atrioventricular blocks and abnormal ventricular depolarization (prolonged and fragmented QRS complex), as well as repolarization (long QT interval) patterns, were observed during the acute phase of myocardial ischemia. A remarkable 100% survival rate was observed among juvenile trout subjected to coronary ligation after 24 wk. Recovery from coronary ligation occurred through adaptive ventricular remodeling, coupled with a fast cardiac revascularization response. These findings carry significant implications for understanding the mechanisms governing cardiac health in salmonid fish, a family particularly susceptible to cardiac diseases. Furthermore, our results provide valuable insights into comparative studies on the evolution, pathophysiology, and ontogeny of vertebrate cardiac repair and restoration. NEW & NOTEWORTHY Juvenile rainbow trout exhibit a remarkable capacity to recover from cardiac injury caused by myocardial ischemia. Recovery from cardiac damage occurs through adaptive ventricular remodeling, coupled with a rapid cardiac revascularization response. These findings carry significant implications for understanding the mechanisms governing cardiac health within salmonid fishes, which are particularly susceptible to cardiac diseases. [ABSTRACT FROM AUTHOR]

We aimed to determine the relative contribution of hypercapnia and hypoxia to the bradycardic response to apneas. We hypothesized that apneas with hypercapnia would cause greater bradycardia than normoxia, similar to the response seen with hypoxia, and that apneas with hypercapnic hypoxia would induce greater bradycardia than hypoxia or hypercapnia alone. Twenty‐six healthy participants (12 females; 23 ± 2 years; BMI 24 ± 3 kg/m2) underwent three gas challenges: hypercapnia (+5 torr end tidal partial pressure of CO2 [PETCO2]), hypoxia (50 torr end tidal partial pressure of O2 [PETO2]), and hypercapnic hypoxia (combined hypercapnia and hypoxia), with each condition interspersed with normocapnic normoxia. Heart rate and rhythm, blood pressure, PETCO2, PETO2, and oxygen saturation were measured continuously. Hypercapnic hypoxic apneas induced larger bradycardia (−19 ± 16 bpm) than normocapnic normoxic apneas (−11 ± 15 bpm; p = 0.002), but had a comparable response to hypoxic (−19 ± 15 bpm; p = 0.999) and hypercapnic apneas (−14 ± 14 bpm; p = 0.059). Hypercapnic apneas were not different from normocapnic normoxic apneas (p = 0.134). After removal of the normocapnic normoxic heart rate response, the change in heart rate during hypercapnic hypoxia (−11 ± 16 bpm) was similar to the summed change during hypercapnia+hypoxia (−9 ± 10 bpm; p = 0.485). Only hypoxia contributed to this bradycardic response. Under apneic conditions, the cardiac response is driven by hypoxia. [ABSTRACT FROM AUTHOR]

Studies indicate cardiac arrhythmia is one of the leading causes of death in the world. The risk of a stroke may be reduced when an irregular and fast heart rate is diagnosed. Since it is non-invasive, electrocardiograms are often used to detect arrhythmias. Human data input may be error-prone and time-consuming because of these limitations. For early detection of heart rhythm problems, it is best to use deep learning models. In this paper, a hybrid bio-inspired algorithm has been proposed by combining whale optimization (WOA) with adaptive particle swarm optimization (APSO). The WOA is a recently developed meta-heuristic algorithm. APSO is used to increase convergence speed. When compared to conventional optimization methods, the two techniques work better together. MIT-BIH dataset has been utilized for training, testing and validating this model. The recall, accuracy, and specificity are used to measure efficiency of the proposed method. The efficiency of the proposed method is compared with state-of-art methods and produced 98.25 % of accuracy. [ABSTRACT FROM AUTHOR]

In contrast to obstructive sleep apnoea, the peak of sympathetic tone in central sleep apnoea occurs during the hyperventilation phase. To explore the temporal association of premature ventricular complex (PVC) burden in the context of the apnoea/hypopnoea-hyperpnoea cycle, the duration of apnoea/hypopnoea was defined as 100 %. We assessed the PVC burden throughout the apnoea/hypopnoea-hyperpnoea cycle during the periods of ±150 % in 50 % increments before and after the apnoea/hypopnoea phase. In this subanalysis of 54 SERVE-HF patients, PVC burden was 32 % higher in the late hyperventilation period (50–100 % after apnoea/hypopnoea) compared to the apnoea/hypopnoea phase. • After a respiratory event, there was an increase of 32 % in ventricular arrhythmia. • Significant increase of heart rate reflecting sympathetic nervous activation. • More pronounced effect in patients with a lower hypoxaemic burden. [ABSTRACT FROM AUTHOR]

Heart rate variability (HRV) indexes how efficiently we mobilize and utilize limited self-regulatory resources to maintain homeostasis. HRV plays a vital role in regulatory capacity, executive functions, health, and performance. We address common misconceptions regarding cardiovascular health, HRV measurement, and HRV biofeedback training. This review highlights the importance of context and individual differences in interpreting HRV. We debunk common misconceptions to improve HRV biofeedback training for health and performance. [ABSTRACT FROM AUTHOR]

Cardiovascular diseases (CVDs) are highly prevalent, sudden onset, and relatively fatal, posing a significant public health burden. Long-term dynamic electrocardiography, which can continuously record the long-term dynamic ECG activities of individuals in their daily lives, has high research value. However, ECG signals are weak and highly susceptible to external interference, which may lead to false alarms and misdiagnosis, affecting the diagnostic efficiency and the utilization rate of healthcare resources, so research on the quality of dynamic ECG signals is extremely necessary. Aimed at the above problems, this paper proposes a dynamic ECG signal quality assessment method based on CNN and LSTM that divides the signal into three quality categories: the signal of the Q1 category has a lower noise level, which can be used for reliable diagnosis of arrhythmia, etc.; the signal of the Q2 category has a higher noise level, but it still contains information that can be used for heart rate calculation, HRV analysis, etc.; and the signal of the Q3 category has a higher noise level that can interfere with the diagnosis of cardiovascular disease and should be discarded or labeled. In this paper, we use the widely recognized MIT-BIH database, based on which the model is applied to realistically collect exercise experimental data to assess the performance of the model in dealing with real-world situations. The model achieves an accuracy of 98.65% on the test set, a macro-averaged F1 score of 98.5%, and a high F1 score of 99.71% for the prediction of Q3 category signals, which shows that the model has good accuracy and generalization performance. [ABSTRACT FROM AUTHOR]

Cardiac arrhythmias cause depolarization waves to conduct unevenly on the myocardial surface, potentially delaying local components with respect to a previous beat when stimulated at faster frequencies. Despite the diagnostic value of localizing the distinct local electrocardiogram (EGM) components for identifying regions with decrement-evoked potentials (DEEPs), current software solutions do not perform automatic signal quantification. Electrophysiologists must manually measure distances on the EGM signals to assess the existence of DEEPs during pacing or extra-stimuli protocols. In this work, we present a deep learning (DL)-based algorithm to identify decrement in atrial components (measured in the coronary sinus) with respect to their ventricular counterparts from EGM signals, for disambiguating between accessory pathways (APs) and atrioventricular re-entrant tachycardias (AVRTs). Several U-Net and W-Net neural networks with different configurations were trained on a private dataset of signals from the coronary sinus (312 EGM recordings from 77 patients who underwent AP or AVRT ablation). A second, separate dataset was annotated for clinical validation, with clinical labels associated to EGM fragments in which decremental conduction was elucidated. To alleviate data scarcity, a synthetic data augmentation method was developed for generating EGM recordings. Moreover, two novel loss functions were developed to minimize false negatives and delineation errors. Finally, the addition of self-attention mechanisms and their effect on model performance was explored. The best performing model was a W-Net model with 6 levels, optimized solely with the Dice loss. The model obtained precisions of 91.28%, 77.78% and of 100.0%, and recalls of 94.86%, 95.25% and 100.0% for localizing local field, far field activations, and extrastimuli, respectively. The clinical validation model demonstrated good overall agreement with respect to the evaluation of decremental properties. When compared to the criteria of electrophysiologists, the automatic exclusion step reached a sensitivity of 87.06% and a specificity of 97.03%. Out of the nonexcluded signals, a sensitivity of 96.77% and a specificity of 95.24% was obtained for classifying them into decremental and non-decremental potentials. Current results show great promise while being, to the best of our knowledge, the first tool in the literature allowing the delineation of all local components present in an EGM recording. This is of capital importance at advancing processing for cardiac electrophysiological procedures and reducing intervention times, as many diagnosis procedures are performed by comparing segments or late potentials in subsequent cardiac cycles. [ABSTRACT FROM AUTHOR]

Electrocardiogram (ECG) abnormalities are the most common cardiac complications after acute ischemic stroke (AIS) and predict poor outcomes. The arterial baroreflex is an essential determinant of cardiovascular autonomic regulation, with receptors mainly residing in carotid sinuses and aortic arch. The atherosclerosis of these baroreceptor-resident arteries (BRA) is very common in AIS patients and might impair baroreflex function. However, the associations between the atherosclerosis of BRA and ECG abnormalities after AIS are still unknown. In total, 228 AIS patients within 7 days after onset without a pre-existing heart disease were prospectively recruited. With computed tomography angiography, atherosclerosis conditions in 10 segments of the carotid sinuses and aortic arch were scored and summed as the Total Atherosclerosis Burden of BRA (TAB-BRA), and asymptomatic coronary artery stenosis (ACAS) ≥50% was simultaneously assessed. We performed 12-lead ECG to dynamically detect abnormal repolarization, and 24 h Holter ECG to monitor arrhythmias and heart rate variability (HRV) parameters, which are reliable indicators to assess cardiac autonomic function. We found that TAB-BRA was positively associated with abnormal repolarization (OR 1.09; CI% 1.03–1.16; p = 0.003) and serious cardiac arrhythmias (OR 1.08; CI% 1.01–1.15; p = 0.021). In addition, TAB-BRA was an important predictor of abnormal repolarization, persisting over 3 days (OR 1.17; CI% 1.05–1.30; p = 0.003). However, ACAS ≥ 50% did not relate to these ECG abnormalities. TAB-BRA was negatively correlated with parasympathetic-related HRV parameters. Our results indicated that AIS patients with a high TAB-BRA are more likely to have ECG abnormalities and delayed normalization, which may relate to the decreased cardiac parasympathetic activity, but not the accompanied ACAS ≥ 50%. [ABSTRACT FROM AUTHOR]

Objective: We aimed to characterize several aspects of retinal vascular dynamics in a patient with arrythmia in order to elicit additional diagnostic information on microvascular dysfunction. Methods: A 68‐year‐old male patient with arrythmia and an age‐ and gender‐matched control subject underwent ocular examination including dynamic retinal vessel assessment with flicker light provocation. Retinal vessel diameters were measured continuously following a standard protocol (IMEDOS Systems, Jena, Germany). The data were evaluated using methods of signal analysis. Results: Retinal vessel response following flicker provocation as well as local structural and functional behavior of retinal vessels were comparable between both individuals. The arrhythmia case demonstrated irregular arterial and venous heart rate (HR) pulsation with an average frequency of 1 Hz. Moreover, the case showed a higher magnitude and larger periods of low‐frequency retinal vessel oscillations as well as lower periodicity of both HR pulsations and low‐frequency vasomotions. Conclusions: Besides numerical examination of irregular HR pulsations in case of arrhythmia, from the direct noninvasive assessment of retinal vessel dynamics one can derive more detailed information on microvascular function including the whole spectrum of retinal arterial and venous pulsations and vasomotions. This may have implications for health screening not limited to atrial fibrillation. [ABSTRACT FROM AUTHOR]

Bupropion is a popular antidepressant due to its favorable side effect profile and indications for smoking cessation and weight loss. Due to the possibility of delayed onset seizure and other adverse outcomes after bupropion overdose, patients are often observed for periods of 12-24 hours following suspected ingestion. Tachycardia is a clinical predictor that holds promise in differentiating cases at risk for seizures from low-risk cases that do not require prolonged observation. This study assessed whether heart rate within the first eight hours of presentation can identify cases that do not require extended observation. This is a retrospective cohort study of all supra-therapeutic bupropion cases from two hospital systems between 2010 and 2022. Data from 216 charts were included. Seizures, hypotension, and dysrhythmias occurred in 19 percent (n = 41), 1.4 percent (n = 3), 0.9 percent (n = 2) respectively. One patient died. Delayed adverse effects were rare (n = 4); they occurred from 14 hours to 28 hours post-ingestion. Maximum heart rate in eight hours was associated with a risk of adverse outcomes. (odds ratio, 1.07; 95 percent confidence interval: 1.05 to 1.09; P < 0.001). An eight hour maximum heart rate threshold of 104 beats/minute had a negative predictive value of 100 percent (95 percent confidence interval: 96.7 percent to 100 percent) for the occurrence of delayed adverse effects. All patients with delayed effects had tachycardia within five hours of emergency department arrival. Delayed adverse outcomes of seizures, hypotension, dysrhythmia, and death were uncommon in this cohort. Heart rate during the first eight hours of observation performs reliably as a screening test to identify patients at low risk for delayed adverse outcomes. This study is limited by its retrospective nature, the inability to ascertain time of ingestion for most cases and the lack of confirmatory laboratory testing. This study supports the use of an eight hour observation period when there are no other clinical signs of toxicity to warrant admission and if no co-ingestion or administration of substances that mask tachycardia are present. [ABSTRACT FROM AUTHOR]

The paper presents a system for analyzing cardiac activity with the possibility of continuous and remote monitoring. The created sensor mobile device monitors heart activity by means of the convenient and imperceptible registration of cardiac signals. At the same time, the behavior of the human body is also monitored through the accelerometer and gyroscope built into the device, thanks to which it is possible to signal in the event of loss of consciousness or fall (in patients with syncope). Conducting real-time cardio monitoring and the analysis of recordings using various mathematical methods (linear, non-linear, and graphical) enables the research, accurate diagnosis, timely assistance, and correct treatment of cardiovascular diseases. The paper examines the recordings of patients diagnosed with arrhythmia and syncope recorded by electrocardiography (ECG) sensors in real conditions. The obtained results are subjected to statistical analysis to determine the accuracy and significance of the obtained results. The studies show significant deviations in the patients with arrhythmia and syncope regarding the obtained values of the studied parameters of heart rate variability (HRV) from the accepted normal values (for example, the root mean square of successive differences between normal heartbeats (RMSSD) in healthy individuals is 24.02 ms, while, in patients with arrhythmia (6.09 ms) and syncope (5.21 ms), it is much lower). The obtained quantitative and graphic results identify some possible abnormalities and demonstrate disorders regarding the activity of the autonomic nervous system, which is directly related to the work of the heart. [ABSTRACT FROM AUTHOR]

Introduction Evidence is mounting that electronic cigarette (e-cig) use induces cardiac sympathetic dominance and electrical dysfunction conducive to arrhythmias and dependent upon nicotine. A variety of nicotine types and concentrations are available in e-cigs, but their relative cardiovascular effects remain unclear. Here we examine how different nicotine forms (racemic, free base, and salt) and concentrations influence e-cig-evoked cardiac dysfunction and arrhythmogenesis and provide a mechanism for nicotine-salt-induced autonomic imbalance. Methods ECG-telemetered C57BL/6J mice were exposed to filtered air (FA) or e-cig aerosols from propylene glycol and vegetable glycerin solvents either without nicotine (vehicle) or with increasing nicotine concentrations (1%, 2.5%, and 5%) for three 9-minute puff sessions per concentration. Spontaneous ventricular premature beat (VPB) incidence rates, heart rate, and heart rate variability (HRV) were compared between treatments. Subsequently, to test the role of β1-adrenergic activation in e-cig-induced cardiac effects, mice were pretreated with atenolol and exposed to either FA or 2.5% nicotine salt. Results During puffing and washout phases, ≥2.5% racemic nicotine reduced heart rate and increased HRV relative to FA and vehicle controls, indicating parasympathetic dominance. Relative to both controls, 5% nicotine salt elevated heart rate and decreased HRV during washout, suggesting sympathetic dominance, and also increased VPB frequency. Atenolol abolished e-cig-induced elevations in heart rate and declines in HRV during washout, indicating e-cig-evoked sympathetic dominance is mediated by β1-adrenergic stimulation. Conclusions Our findings suggest that inhalation of e-cig aerosols from nicotine-salt-containing e-liquids could increase the cardiovascular risks of vaping by inducing sympathetic dominance and cardiac arrhythmias. Implications Exposure to e-cig aerosols containing commercially relevant concentrations of nicotine salts may increase nicotine delivery and impair cardiac function by eliciting β1-adrenoceptor-mediated sympathoexcitation and provoking ventricular arrhythmias. If confirmed in humans, our work suggests that regulatory targeting of nicotine salts through minimum pH standards or limits on acid additives in e-liquids may mitigate the public health risks of vaping. [ABSTRACT FROM AUTHOR]

Obstructive sleep apnea (OSA) is associated with the progression of cardiovascular diseases, arrhythmias, and sudden cardiac death (SCD). However, the acute impacts of OSA and its consequences on heart function are not yet fully elucidated. We hypothesized that desaturation events acutely destabilize ventricular repolarization, and the presence of accompanying arousals magnifies this destabilization. Ventricular repolarization lability measures, comprising heart rate corrected QT (QTc), short-time-variability of QT (STVQT), and QT variability index (QTVI), were calculated before, during, and after 20,955 desaturations from lead II electrocardiography signals of 492 patients with suspected OSA (52% men). Variations in repolarization parameters were assessed during and after desaturations, both with and without accompanying arousals, and groupwise comparisons were performed based on desaturation duration and depth. Regression analyses were used to investigate the influence of confounding factors, comorbidities, and medications. The standard deviation (SD) of QT, mean QTc, SDQTc, and STVQT increased significantly (P < 0.01), whereas QTVI decreased (P < 0.01) during and after desaturations. The changes in SDQT, mean QTc, SDQTc, and QTVI were significantly amplified (P < 0.01) in the presence of accompanying arousals. Desaturation depth was an independent predictor of increased SDQTc (β = 0.405, P < 0.01), STVQT (β = 0.151, P < 0.01), and QTVI (β = 0.009, P < 0.01) during desaturation. Desaturations cause acute changes in ventricular repolarization, with deeper desaturations and accompanying arousals independently contributing to increased ventricular repolarization lability. This may partially explain the increased risk of arrhythmias and SCD in patients with OSA, especially when the OSA phenotype includes high hypoxic load and fragmented sleep. NEW & NOTEWORTHY Nocturnal desaturations are associated with increased ventricular repolarization lability. Deeper desaturations with accompanying arousals increase the magnitude of alterations, independent of confounding factors, comorbidities, and medications. Changes associated with desaturations can partially explain the increased risk of arrhythmias and sudden cardiac death in patients with OSA, especially in patients with high hypoxic load and fragmented sleep. This highlights the importance of detailed electrocardiogram analytics for patients with OSA. [ABSTRACT FROM AUTHOR]

Duchenne muscular dystrophy (DMD) patients exhibit a late left ventricular systolic dysfunction preceded by an occult phase, during which myocardial fibrosis progresses and some early functional impairments can be detected. These latter include electrocardiographic (ECG) and heart rate variability (HRV) abnormalities. This longitudinal study aimed at describing the sequence of ECG and HRV abnormalities, using Holter ECG in the GRMD (Golden retriever muscular dystrophy) dog model, known to develop a DMD-like disease, including cardiomyopathy. Most of the known ECG abnormalities described in DMD patients were also found in GRMD dogs, including increased heart rate, prolonged QT and shortened PR intervals, ventricular arrhythmias, and several of them could be detected months before the decrease of fractional shortening. The HRV was impaired like in DMD patients, one of the earliest evidenced abnormalities being a decrease in the very low frequency (VLF) component of the power spectrum. This decrease was correlated with the further reduction of fractional shortening. Such decreased VLF probably reflects impaired autonomic function and abnormal vasomotor tone. This study provides new insights into the knowledge of the GRMD dog model and DMD cardiomyopathy and emphasizes the interest to monitor the VLF power in DMD patients, still unexplored in this disease, whilst it is highly predictive of deleterious clinical events in many other pathological conditions. [ABSTRACT FROM AUTHOR]

Background: The need for mobile-based ambulatory heart rhythm monitoring arises from its potential to provide convenient and continuous tracking of heart rhythms, improving early detection and management of cardiac issues while accommodating patients' active lifestyles. The present study aims to compare and validate the 24 h ECG monitoring between the traditional Holter and Vigo Heart wearable patch. Method: One hundred and nineteen patients with a workup of pre-diagnosed arrhythmias or suspicious arrhythmic episodes were evaluated. Each participant wore both devices simultaneously, and the cardiac rhythm was monitored for 24 h. Selective ECG parameters were compared between the two devices and the cardiologist independently compared the diagnoses of each device. Results: The indication for ECG monitoring in the ent study was patients who were presented with suspicious arrhythmia-related symptoms (47.8%). The Vigo Heart ECG showed a negligible amount of mean noise percentage (1.94 ±6.68%) when compared with the traditional Holter 17.84±23.95% of the total recording time. For the maximum heart rate, there was significant correlation between the Holter monitoring and Vigo Heart patch (129.69 ± 22.5 vs. 113.31 ± 23.6 beats/min, p = 0.02). The results also showed significant correlation for the average heart rates (74.85 ± 10.8 vs. 76 ± 10.3 beats/min, p = 0.02) and minimum heart rates (47.94 ± 9.5 vs. 59.21 ± 8.9 beats/min, p = 0.02), for the Vigo Heart ECG and Holter monitoring, respectively. The cardiologist made coherent clinical diagnoses for all the 119 study participants using both the ECG monitoring devices. The findings also revealed comparable coherent detection of cardiac arrhythmias in both the ECG monitoring devices. Conclusion: The single-lead adhesive device presents itself as a viable and acceptable alternative for conducting ambulatory ECG monitoring in individuals with arrhythmia or suspicious symptoms of arrhythmias. [ABSTRACT FROM AUTHOR]

This document is a compilation of articles and reviews on various topics in cardiology. The articles cover subjects such as the prevalence of arrhythmia in adults after a specific operation, outcomes of patients after resuscitated cardiac arrest, and catheter ablation of ventricular arrhythmias. The reviews discuss topics like the pathogenesis and management of a specific syndrome, molecular mechanisms of arrhythmias, and structural heart alterations in that syndrome. The authors have declared their contributions and any conflicts of interest. The document provides valuable information for researchers and healthcare professionals interested in cardiology. [Extracted from the article]

Etripamil, a fast‐acting nondihydropyridine L‐type calcium channel blocker, is under investigation for potential self‐administration for the acute treatment of supraventricular tachyarrhythmias in a medically unsupervised setting. We report detailed pharmacokinetics and pharmacodynamics of intranasally administered etripamil in healthy adults from 2 Phase 1, randomized, double‐blind studies: Study MSP‐2017‐1096 (sequential dose‐escalation, crossover study design, n = 64) and NODE‐102 (single dose, 4‐way crossover study, n = 24). Validated bioanalytical assays determined plasma concentrations of etripamil and its inactive metabolite. Noncompartmental pharmacokinetic parameters were calculated. Pharmacodynamic parameters were determined for PR interval, blood pressure, and heart rate. Etripamil was rapidly absorbed intranasally, with time to maximal plasma concentration of 5‐8.5 minutes, corresponding to a rapid greater than 10% increase in mean maximum PR interval from baseline within 4‐7 minutes of doses of 60 mg or greater. Following peak plasma concentrations, systemic etripamil levels declined rapidly within the first 15 minutes following dosing and decreased more gradually thereafter. PR interval prolongation greater than 10% from baseline was generally sustained for about 45 minutes at doses of 60 mg or greater. The mean terminal half‐life ranged from about 1.5 hours with 60 mg to about 2.5‐3 hours for the 70‐ and 105‐mg doses. Etripamil was generally well tolerated without symptomatic hypotension. Adverse events were primarily mild to moderate and related to the administration site; no serious adverse events or episodes of atrioventricular block occurred. Intranasal etripamil administration, at doses of 60 mg or greater, produced rapidly occurring slowing of atrioventricular nodal conduction with a limited duration of effect without hemodynamic or electrocardiographic safety signals in healthy volunteers. [ABSTRACT FROM AUTHOR]

Landiolol is an ultra-short-acting, selective β1-adrenergic receptor blocker that was originally approved in Japan for the treatment of intraoperative tachyarrhythmias. It has gained attention for its use in the management of tachyarrhythmias and perioperative tachycardia, especially atrial fibrillation for both cardiac and non-cardiac surgeries. It can be the ideal agent for heart rate control due to its high β1-selectivity, potent negative chronotropic effect, a limited negative inotropic potential, and an ultrashort elimination half-life (around 4 min); moreover, it may have a potential therapeutic effects for sepsis and pediatric patients. Landiolol seems to be superior to other short-acting and selective beta-blockers such as esmolol. This review aims to provide a comprehensive overview of landiolol, a new ultra-short-acting β1 selective antagonist, including its pharmacology, clinical applications, efficacy, safety profile, and future directions in research and clinical data. [ABSTRACT FROM AUTHOR]

In this paper, a novel method is introduced to diagnose the cardiac arrhythmias. Automatic diagnosis of cardiac arrhythmias is crucial for successful treatment of heart diseases, and nowadays, machine learning is used to facilitate this purpose. For accurate classification of arrhythmias, it is vital to extract some appropriate features which distinguish different classes. In this research, a deep convolutional neural network is used to extract the features. Since the heart rates of various patients are very different, arrhythmias of a specific class will be placed in different locations of feature space. To reduce the intra-class variations, each patient's heart rate is mapped with a dedicated function to increase its similarity to the heart rate of a training patient. The proposed patient-specific mapping decreases the intra-class variation and significantly increases the classification accuracy of cardiac arrhythmias. The calculated accuracy is about 91.08%, which shows the better performance compared to other similar works. [ABSTRACT FROM AUTHOR]

Background: Individuals with serious mental illness have a markedly shorter life expectancy. A major contributor to premature death is cardiovascular disease (CVD). We investigated associations of (genetic liability for) depressive disorder, bipolar disorder and schizophrenia with a range of CVD traits and examined to what degree these were driven by important confounders. Methods: We included participants of the Dutch Lifelines cohort (N = 147 337) with information on self-reported lifetime diagnosis of depressive disorder, bipolar disorder, or schizophrenia and CVD traits. Employing linear mixed-effects models, we examined associations between mental illness diagnoses and CVD, correcting for psychotropic medication, demographic and lifestyle factors. In a subsample (N = 73 965), we repeated these analyses using polygenic scores (PGSs) for the three mental illnesses. Results: There was strong evidence that depressive disorder diagnosis is associated with increased arrhythmia and atherosclerosis risk and lower heart rate variability, even after confounder adjustment. Positive associations were also found for the depression PGSs with arrhythmia and atherosclerosis. Bipolar disorder was associated with a higher risk of nearly all CVD traits, though most diminished after adjustment. The bipolar disorder PGSs did not show any associations. While the schizophrenia PGSs was associated with increased arrhythmia risk and lower heart rate variability, schizophrenia diagnosis was not. All mental illness diagnoses were associated with lower blood pressure and a lower risk of hypertension. Conclusions: Our study shows widespread associations of (genetic liability to) mental illness (primarily depressive disorder) with CVD, even after confounder adjustment. Future research should focus on clarifying potential causal pathways between mental illness and CVD. [ABSTRACT FROM AUTHOR]

Recent experimental evidence suggests combined treatment with midazolam and allopregnanolone is more effective than midazolam alone in terminating seizures triggered by acute organophosphate (OP) intoxication. However, there are concerns that combined midazolam and allopregnanolone increases risk of adverse cardiovascular events. To address this, we used telemetry devices to record cardiovascular responses in adult male Sprague–Dawley rats acutely intoxicated with diisopropylfluorophosphate (DFP). Animals were administered DFP (4 mg/kg, sc), followed immediately by atropine (2 mg/kg, i.m.) and 2-PAM (25 mg/kg, i.m.). At 40 min post-exposure, a subset of animals received midazolam (0.65 mg/kg, im); at 50 min, these rats received a second dose of midazolam or allopregnanolone (12 mg/kg, im). DFP significantly increased blood pressure by ~ 80 mmHg and pulse pressure by ~ 34 mmHg that peaked within 12 min. DFP also increased core temperature by ~ 3.5 °C and heart rate by ~ 250 bpm that peaked at ~ 2 h. Heart rate variability (HRV), an index of autonomic function, was reduced by ~ 80%. All acute (within 15 min of exposure) and two-thirds of delayed (hours after exposure) mortalities were associated with non-ventricular cardiac events within 10 min of cardiovascular collapse, suggesting that non-ventricular events should be closely monitored in OP-poisoned patients. Compared to rats that survived DFP intoxication without treatment, midazolam significantly improved recovery of cardiovascular parameters and HRV, an effect enhanced by allopregnanolone. These data demonstrate that midazolam improved recovery of cardiovascular and autonomic function and that the combination of midazolam and allopregnanolone may be a better therapeutic strategy than midazolam alone. [ABSTRACT FROM AUTHOR]

Mitiperstat is a myeloperoxidase inhibitor in clinical development for treatment of patients with heart failure and preserved or mildly reduced ejection fraction, non‐alcoholic steatohepatits and chronic obstructive pulmonary disease. We aimed to assess the risk of QT‐interval prolongation with mitiperstat using concentration–QT (C‐QT) modeling. Healthy male volunteers were randomized to receive single oral doses of mitiperstat 5, 15, 45, 135, or 405 mg (n = 6 per dose) or matching placebo (n = 10) in a phase 1 study (NCT02712372). Time‐matched pharmacokinetic and digital electrocardiogram data were collected at the baseline (pre‐dose) and at 11 time‐points up to 48 h post‐dose. C‐QT analysis was prespecified as an exploratory objective. The prespecified linear mixed effects model used baseline‐adjusted QT interval corrected for the heart rate by Fridericia's formula (ΔQTcF) as a dependent variable and plasma mitiperstat concentration as an independent variable. Initial exploratory analyses indicated that all model assumptions were met (no effect on heart rate; appropriate use of QTcF; no hysteresis; linear concentration–response relationship). Model‐predicted mean baseline‐corrected and placebo‐adjusted ΔΔQTcF was +0.73 ms (90% confidence interval [CI]: −1.73, +3.19) at the highest anticipated clinical exposure (0.093 μmol/L) during treatment with mitiperstat 5 mg once daily. The upper 90% CI was below the established threshold of regulatory concern. The 16‐fold margin to the highest observed exposure was high enough to mean that a positive control was not needed. Mitiperstat is not associated with risk of QT‐interval prolongation at expected therapeutic concentrations. [ABSTRACT FROM AUTHOR]

One of the complications during an acute coronary syndrome event is the presence of arrhythmias. Among them, those of the supraventricular type, especially atrial fibrillation, carry a poor prognosis both in the short and long term, being the cause of situations such as cerebrovascular event, ventricular arrhythmias, and increased mortality. The arrhythmia tends to appear in a certain population group with particular risk factors during the index event in approximately 10% of cases. Appropriate treatment at the time of its onset, thanks to the use of drugs that modulate heart rate, rhythm, and anticoagulant management in the most vulnerable groups, will lead to a less bleak outcome for these patients. [ABSTRACT FROM AUTHOR]

Background: Early detection of atrial fibrillation (AF) is essential to prevent stroke and other cardiac and embolic complications. We compared the diagnostic properties for AF detection of the percentage of successive RR interval differences greater than or equal to 30 ms or 3.25% of the previous RR interval (pRR30 and pRR3.25%, respectively), and asymmetric entropy descriptors of RR intervals. Previously, both pRR30 and pRR3.25% outperformed many other heart rate variability (HRV) parameters in distinguishing AF from sinus rhythm (SR) in 60 s electrocardiograms (ECGs). Methods: The 60 s segments with RR intervals were extracted from the publicly available Physionet Long-Term Atrial Fibrillation Database (84 recording, 24 h Holter ECG). There were 31,753 60 s segments of AF and 32,073 60 s segments of SR. The diagnostic properties of all parameters were analysed with receiver operator curve analysis, a confusion matrix and logistic regression. The best model with pRR30, pRR3.25% and total entropic features (H) had the largest area under the curve (AUC)—0.98 compared to 0.959 for pRR30—and 0.972 for pRR3.25%. However, the differences in AUC between pRR30 and pRR3.25% alone and the combined model were negligible from a practical point of view. Moreover, combining pRR30 and pRR3.25% with H significantly increased the number of false-negative cases by more than threefold. Conclusions: Asymmetric entropy has some potential in differentiating AF from SR in the 60 s RR interval time series, but the addition of these parameters does not seem to make a relevant difference compared to pRR30 and especially pRR3.25%. [ABSTRACT FROM AUTHOR]