Vitamin A is an essential micronutrient involved in growth, immune regulation, and central nervous system function; however, excessive intake may disrupt systemic homeostasis. This study investigated the electrophysiological effects of experimental hypervitaminosis A on hippocampal activity and cardiac function in male Wistar rats. Animals received a supraphysiological dose of vitamin A (50,000 IU/kg, intraperitoneally) once daily for 3, 7, or 14 days. Serum calcium levels were quantified, and electrophysiological recordings were obtained from the CA1 hippocampal region (EEG) and through electrocardiography (ECG). Vitamin A administration produced a time-dependent increase in total hippocampal spectral power. Power elevations were observed across multiple frequency bands, particularly theta (4-8 Hz), α (8-12 Hz), β (12-28 Hz), and γ (28-40 Hz) oscillations after 7 and 14 days of exposure. Serum calcium levels showed modest increases but remained within physiological reference ranges. Cardiac assessment revealed increased heart rate accompanied by reductions in R-R and QT intervals while maintaining sinus rhythm and preserved ECG morphology. These findings demonstrate that short-term exposure to supraphysiological vitamin A levels alters hippocampal oscillatory dynamics and modulates cardiac electrophysiological parameters in rats. Although the functional and mechanistic implications require further investigation, the results indicate that excessive vitamin A intake can influence neurocardiac electrophysiological homeostasis even in the absence of overt hypercalcemia.

Background and Objectives: The interaction between the brain and heart has become more interesting in the last 20 years. The most common cardiac complications after stroke are myocardial infarction, heart failure, arrhythmias, electrocardiographic disturbances, repolarization disorders, and sudden cardiac death. The prolonged Tpeak-Tend interval is an indicator of the electrical heterogeneity of the myocardium (abnormal repolarization) that causes malignant arrhythmias. We aimed to investigate whether the Tpeak-Tend interval, which reflects the heterogeneity of repolarization, is prolonged in stroke and its relationship with short-term mortality. Materials and Methods: Individuals over the age of 18 who presented with hemorrhagic or ischemic stroke were included in the study. Demographic characteristics, laboratory and imaging findings of the patients were recorded. ECGs were obtained at the time of admission to the hospital and 24 h later. Patients were followed for in-hospital mortality. Results: 89 (82.4%) of the patients had ischemic stroke, 19 (17.6%) had hemorrhagic stroke. It was determined that Tp-eV2 and Tp-eV5 at hospital admission were significantly longer than the 24th hour values. A total of 92.01 (16.3) ms at Tp-eV2 admission, 84.1 (16.3) ms after 24 h (p = 0.003), 91.9 (7.3) msTp-eV5 at admission, and 81.6 (17.8) ms (p = 0.000) after 24 h. In multivariate logistic regression analysis of in-hospital mortality, Tp-eV2 (HR: 0.96 (95% CI 0.93-0.99) p = 0.008) was determined as an independent predictor among cardiovascular parameters. Conclusions: Tp-e intervals were prolonged in both leads V2 and V5 in patients with stroke. Prolongation of lead V2 in the Tp-e interval is an independent indicator of short-term mortality among cardiovascular parameters.

Electrocardiography (ECG) plays a vital role in the diagnosis of cardiovascular diseases by analyzing the electrical activity of the heart. ECG semantic segmentation is a subfield focused on sample-wise delineation of ECG waveforms by assigning a physiological label to each time sample, enabling explicit estimation of clinically meaningful onset and offset boundaries. Recent advancements in deep learning have significantly improved ECG classification accuracy; however, the same has not yet been observed in automatic ECG segmentation. Existing models often lack explainability and adaptability to patient-specific variations, thereby reducing their generalizability. This study proposes a personalized deep neural network approach for enhanced ECG processing. This method incorporates convolutional neural networks (CNNs) and bidirectional long short-term memory (BiLSTM) networks, incorporating an attention mechanism to refine segmentation accuracy. A novel loss function is introduced to ensure smoother temporal transitions and better classification accuracy. The model was evaluated using the QT Database, demonstrating substantial improvements in P-wave and QRS delineation and in T-wave offset localization segmentation when fine-tuned for individual patients when fine-tuned and evaluated on held-out data from the same patient, demonstrating the benefit of intra-patient adaptation. Our results indicate that personalization improves delineation accuracy for challenging waveforms (notably P and T waves), supporting the potential of deep learning to better capture patient-specific morphology and providing a stronger basis for waveform-level, clinically interpretable ECG analysis.

Long QT Syndrome (LQTS) is an inherited cardiac disorder characterized by dysfunctional cardiac ion channels, which result in prolonged QT intervals on electrocardiograms (ECGs). LQTS can lead to severe clinical manifestations, including syncope, ventricular arrhythmias, and sudden cardiac death. Effective genotype-specific management strategies are essential to mitigate the risk of life-threatening arrhythmias. This study aims to achieve automatic discrimination among the LQT1, LQT2, and LQT3 genotypes to enable targeted treatment and prevention strategies. Utilizing ECG data from the Telemetric and Holter ECG Warehouse's LQTS database, our methodology involves an automated extraction process of short ECG signals, geometric parameterization techniques, and classification using a two-stage cascade of binary support vector machine classifiers. The input features for the classifiers are derived from Lead I ECG signals sampled at 200 Hz, highlighting the potential application in developing single-lead ECG monitoring devices and applications, such as widely used smartwatches, for which short recording duration, low sampling frequency, and arm-to-arm lead measurements are fundamental prerequisites for practical use. The proposed classifier achieved 71% weighted accuracy on out-of-sample data (LQT1: 65% recall, 58% precision; LQT2: 79% recall, 82% precision; and LQT3: 71% recall, 77% precision). Our findings demonstrate the feasibility of noninvasive genotype differentiation for LQTS based on the morphological analysis of ECG signals, providing an advancement in the field of personalized cardiology and the development of portable diagnostic tools.

Background and Objectives: This study aimed to evaluate the pre- and post-treatment changes in ICEB and ICEBc score markers of cardiac electrical balance in patients presenting to the emergency department with hypertensive urgency and to investigate their relationship with short-term clinical outcomes. Materials and Methods: In this retrospective study, 50 patients who presented to a tertiary university hospital emergency department between 1 January 2021 and 31 December 2024 with a diagnosis of hypertensive urgency and had pre- and post-treatment 12-lead ECGs were analysed. ICEB (QT/QRS) and ICEBc (QTc/QRS) scores were calculated manually. Patients were categorized as discharged or hospitalized. Within-group and between-group comparisons of the scores were performed. Results: Of the patients, 66% were female, and the mean age was 60.4 ± 14.5 years. A statistically significant increase in ICEB scores was observed after treatment in discharged patients (p = 0.006), whereas ICEBc scores showed no significant change. In the hospitalized group, no significant difference was found in either ICEB or ICEBc scores. Additionally, between-group comparisons revealed no significant differences in ICEBc values. Conclusions: The ICEB score may serve as a dynamic marker reflecting the electrophysiological response to antihypertensive treatment. The observed increase in ICEB after treatment may indicate the restoration of electrical stability. In contrast, ICEBc appeared to have limited predictive value in this clinical context. Further prospective studies with larger populations are needed to determine the clinical utility of ICEB in the management of hypertensive crises.

Understanding the dynamic relationship between RR and QT intervals is crucial for interpreting electrocardiograms (ECGs) and managing cardiac conditions. Here we focus specifically on the short-range, beat-to-beat coupling between RR and QT intervals, which we investigate in long-term ECG recordings from 202 healthy subjects using time-lagged cross-correlation (TLCC) analysis. This approach allows us to quantify how QT intervals relate to both preceding and succeeding RR intervals across a range of short time lags. Data were preprocessed with the smoothness priors method to remove long-term trends while preserving relevant short-term dynamics. Understanding the dynamic relationship between RR and QT intervals is crucial for interpreting electrocardiograms (ECGs) and managing cardiac conditions. We investigated cross-correlation between RR and QT intervals in long-term ECG recordings from 202 healthy subjects using time-lagged cross-correlation analysis to explore how QT intervals correlate with both preceding and succeeding RR intervals across various time lags. Data was preprocessed with the smoothness priors method to remove long-term trends while preserving relevant short-term dynamics. Our results reveal that, as expected, the highest RR-QT cross-correlations occur when the intervals overlap the most. Notably, we also observed a strong cross-correlation between the present QT interval and the preceding RR interval, with the overall correlations skewed toward negative lags. This suggests that past RR intervals exert a stronger influence on current QT intervals. These findings align with previous research on RR-QT transfer entropy. We found no significant differences in RR-QT cross-correlations between sexes. However, aging was associated with significantly reduced cross-correlations across all lags. This effect is consistent with existing literature on age-related cardiac changes and provides further insight into the impact of aging on RR-QT coupling. Additionally, we observed a slight positive correlation between heart rate and cross-correlation at all lags, with cross-correlation decreasing as the lag increased. These findings enhance our understanding of the dynamic RR-QT relationship by characterizing its short-range structure in a model-free way. The empirical patterns offer a reference for normal RR-QT dynamics in healthy individuals and may support future development or validation of dynamical QT/RR models.

Doxorubicin (DOX), an effective anthracycline chemotherapeutic agent, induces cardiotoxicity through oxidative stress, mitochondrial dysfunction, and activation of apoptotic pathways. As millimeter-wave frequencies used in fifth-generation (5G) communication systems continue to expand, experimental data on potential biological interactions under clinically relevant conditions remain limited. This study investigated whether short-term 28-GHz electromagnetic radiation (EMR) modifies the cardiac response to DOX and evaluated the potential protective role of vitamin C. Thirty male Sprague-Dawley rats were assigned to five groups (n = 6): Sham, DOX, DOX + Vit C, DOX + 5G, and DOX + 5G + Vit C. DOX (15 mg/kg intraperitoneally, six injections) induced cardiotoxicity, while vitamin C (250 mg/kg orally) was administered daily for 14 days. EMR exposure consisted of three 10-min cycles per day at 28 GHz for 14 days. Cardiac injury was assessed using electrocardiography, serum cTnI, oxidative markers (MDA, GSH, SOD, CAT), apoptotic and inflammatory gene expression (BAX, CASP3, BCL-2, TNF-α), and design-based stereology. DOX induced significant functional, biochemical, molecular, and structural alterations. Co-exposure to 28-GHz EMR amplified reductions in CAT (p < 0.001), and enhanced pro-apoptotic BAX gene expression (p < 0.0001), accompanied by QT interval prolongation (p < 0.05). Vitamin C provided partial protection across these endpoints. Under the specific short-term pre-clinical conditions tested, these findings indicate that 28-GHz EMR can modulate the severity of DOX-induced cardiotoxicity, while vitamin C confers modest attenuation. Further long-term and clinical studies are needed to clarify mechanisms and refine translational relevance.

A short-QT interval is a potential electrocardiographic finding, while short-QT syndrome (SQTS) is a rare, inherited channelopathy characterized by pathological shortening of the action potential duration leading to an increased risk of life-threatening arrhythmias. In contrast to the long QT syndrome (LQTS), data on the prevalence, diagnosis, risk stratification, treatment and prognosis of short-QT syndrome are scarce. Understanding the true risk of adverse events in exercise population or sporting activities by the patient with short-QT on 12‑leads electrocardiogram is complex: here, we summarize current knowledge and raise questions regarding the challenging relationship between the difficult SQTS diagnosis and exercise practice.

Background/Objectives: High-altitude hypoxia may affect ECG readings, but it is unclear whether the "live-low-train-high" approach prevents these changes in winter sports athletes. Methods: This cross-sectional study assessed cardiovascular parameters in 102 winter-sport athletes (mean age 20 ± 4 y; 57% women), divided by training altitude into a high-altitude (HA) group (2500-3300 m, n = 70; skiers/snowboarders) and a low-altitude (LA) group (738 m, n = 32; ice hockey/figure skaters). Mid-season assessments included resting ECG, blood pressure, blood biochemistry, and three 24 h dietary recalls. Results: All ECG parameters were physiological, and no significant differences (p < 0.05) were observed in heart rate, PR interval, or QTc between groups. However, HA group exhibited higher systolic blood pressure and a short QT interval. Lactate was significantly higher in HA (p = 0.028). The HA diet contained more saturated fat (p < 0.001), cholesterol (p = 0.013), magnesium (p = 0.003) and potassium (p = 0.001), whereas LA athletes consumed more glucose (p = 0.024). In HA, total energy expenditure correlated positively (p ≥ 0.05) with QRS (ρ = 0.52) and QT (ρ = 0.56), while heart rate correlated inversely with vitamin D (ρ = -0.59). In LA, QTc showed strong inverse correlations with zinc (ρ = -0.62) and selenium (ρ = -0.85). Conclusions: This finding suggests that intermittent high-altitude training did not alter ECG patterns when nutrient intake was adequate. High lactate level and specific nutrient correlations point to a residual physiological load and a modulatory role of electrolytes, B-vitamins, and vitamin D on cardiac repolarisation.

The coexistence of atrial fibrillation (AF) and ventricular fibrillation (VF) in a structurally normal heart is a rare presentation. We describe a case of a previously healthy, 30-year-old man presenting with a family history of sudden cardiac death. The ECG during admission showed early repolarization pattern and he spontaneously developed AF, junctional rhythm and VF and dynamic QT shortening with prominent U waves during the arrhythmic storm. Genetic testing revealed novel heterozygous missense substitution p.Ile73Val in exon 2 of the CACNA1C gene.