Search Results (659)

Background: Adaptive deep brain stimulation (aDBS) for Parkinson’s disease (PD) relies on accurate detection of beta oscillatory activity. However, electrocardiographic (ECG) artifacts frequently contaminate local field potentials (LFPs), compromising control algorithms. While offline cleaning methods exist, their feasibility for real-time operation within the strict timing constraints of current sensing-enabled devices remains unknown. Methods: We evaluated four ECG removal algorithms, template subtraction (TS), singular value decomposition (SVD), extended SVD (eSVD), and the Perceive toolbox (PR), on simulated datasets (contaminated at −30 to +20 dB) and clinical recordings from 20 PD patients. Algorithms were assessed for artifact removal quality (beta power preservation, signal-to-noise ratio) and real-time feasibility (99th percentile processing latency—P₉₉ < 50 ms). Results: Only TS and standard SVD met the real-time feasibility threshold, with TS achieving superior timing consistency (P₉₉ ≈ 10 ms). eSVD and PR proved incompatible with closed-loop requirements (P₉₉ > 90 ms). While eSVD yielded the highest artifact suppression at extreme contamination, it suffered from poor signal preservation at moderate levels. TS demonstrated the best balance, maintaining beta power accuracy within ±12% across clinically relevant contamination levels. Conclusions: TS is the recommended method for real-time aDBS applications, offering a safety-critical balance of computational efficiency and biomarker fidelity. Full article

Background: Kounis syndrome is an allergic acute coronary syndrome precipitated by coronary vasospasm, plaque destabilization, stent thrombosis, or bypass occlusion. Cardiac surgery represents a uniquely high-risk setting due to cardiopulmonary bypass–associated inflammation and exposure to multiple pharmaceutical agents. Importantly, Kounis syndrome remains underrecognized in this context, as classical signs of anaphylaxis may be masked under general anesthesia and cardiopulmonary bypass, while ischemic manifestations may be misattributed to other perioperative conditions. Methods: A narrative review of PubMed-indexed literature was conducted to synthesize current evidence on the pathophysiology, perioperative triggers, clinical presentation, diagnostic strategies, and management of Kounis syndrome in cardiac surgery, with emphasis on intraoperative recognition and surgical decision-making. Published cases were retrieved involving perioperative cardiac surgery patients with a definite diagnosis of Kounis syndrome. Additionally, cases presenting with severe perioperative anaphylaxis and life-threatening cardiovascular involvement (grade III with cardiovascular collapse and grade IV with cardiac arrest) were included as possible Kounis syndrome, reflecting real-world diagnostic uncertainty in the intraoperative setting. Results: The literature review identified five cases of definite Kounis syndrome and ten cases of possible Kounis syndrome, including three cases with cardiovascular collapse and seven cases with cardiac arrest. Recurrent episodes were reported in several patients, particularly due to re-exposure to the triggering agent. In the context of cardiac surgery, Kounis syndrome is most frequently triggered by chlorhexidine, protamine, antibiotic prophylaxis, and anesthetic agents. The clinical presentation is often subtle during cardiopulmonary bypass. Vasoplegia, pulmonary hypertension, ventricular dysfunction, new regional wall-motion abnormalities, and hyperdynamic ventricles on transesophageal echocardiography commonly precede overt electrocardiographic changes. Diagnosis is primarily clinical and relies on intraoperative ultrasound, hemodynamic monitoring, serum tryptase, serum troponin, and, when indicated, coronary angiography. A dual-pathway approach addressing both anaphylaxis and myocardial ischemia is essential; however, one component may predominate, particularly in perioperative patients with limited clinical information, potentially leading to misdiagnosis. A multidisciplinary approach is therefore required for rapid diagnosis and individualized management. In refractory cases, cardiopulmonary bypass or ventricular assist devices may provide lifesaving support. Conclusions: Kounis syndrome remains underrecognized in cardiac surgery but carries significant morbidity. Increased clinical awareness, multidisciplinary collaboration, structured diagnostic approaches, and preventive strategies are essential to improve outcomes and reduce the risk of recurrence during future procedures. Full article

Background: Unstable angina has become an exceedingly rare diagnosis in the era of high-sensitivity cardiac troponin (hs-cTn). Objectives: We sought to identify the incidence of unstable angina and characterize patients with low hs-cTn in emergency departments (EDs). Methods: A prespecified secondary analysis of the Rapid Acute Coronary Syndrome Exclusion using high-sensitivity cardiac Troponin I (RACE-IT) trial was conducted. RACE-IT was a stepped-wedge randomized trial comparing two rule-out protocols (0/1- and 0/3 h) for myocardial infarction (MI) in nine EDs from July 2020 to April 2021. All patients had hs-cTnI (Beckman Coulter) concentrations below or equal to the 99th percentile upper reference limit of 18 ng/L. The primary outcome was unstable angina, based on the ISCHEMIA trial definition, which required electrocardiographic changes or findings at coronary angiography (angiographic evidence of plaque rupture or thrombus). Results: Of the 32,608 patients in the trial, 60 patients (0.2%) met the definition of unstable angina, of whom 46 (77%) had obstructive disease at coronary angiography and 17 (28%) had an ischemic electrocardiogram. Coronary revascularization was performed in 45 (75%) patients and seven (12%) had left main or 3-vessel coronary artery disease. There were seven (12%) patients with non-obstructive coronary artery disease, and seven (12%) who had angiographically unremarkable coronary arteries. Patients with unstable angina were older (p = 0.015), more likely to be male (p = 0.005), with a higher prevalence of hypertension (p < 0.001), known coronary artery disease (p < 0.001), peripheral vascular disease (p = 0.035), and a higher serum creatinine (p = 0.018). At 30 days, two patients had a type 1 MI and there were no deaths. Conclusions: Unstable angina was diagnosed in 1 in 500 patients with a low hs-cTnI value at presentation to the ED and these patients had an excellent prognosis at 30 days. These patients tend not to have high-risk anatomy and one in four had non-obstructive coronary artery disease or angiographically unremarkable coronary arteries. Full article

Introduction: Palpitations are one of the most common cardiovascular complaints, affecting approximately 6% to 11% of the general population. Since palpitations often occur sporadically and resolve before medical evaluation, diagnosing the underlying rhythm disturbance requires documentation via an electrocardiogram (ECG) recorded during the symptomatic episode. The standard tool for this purpose has long been the 24-h Holter monitor, which has significant limitations, with diagnostic yields as low as 10% to 15%. Objective: This study aims to evaluate the feasibility and diagnostic yield of single-lead ECG recordings from smartwatches in patients presenting with palpitations. Methods: From 1 May 2023 to 1 May 2025, we conducted a prospective, real-world cohort study among consecutive adults referred to the University Hospital of Ferrara-based arrhythmia outpatient clinics for evaluation of palpitations. Eligibility required patients to be ≥21 years of age, report palpitations for which ambulatory documentation was clinically indicated, and already own a compatible smartwatch capable of single-lead ECG. Participants were trained to record a 30-s single-lead ECG at the onset of symptoms. Tracings were transmitted securely and independently reviewed by two blinded electrophysiologists. Results: Fifty-nine patients were enrolled (mean age 52 years, 64% male). Thirty-one patients (52%) transmitted at least one smartwatch-derived electrocardiographic tracing. Seventy-seven smartwatch tracings were received. Of these, 73 (95%) were interpretable; 57 (78%) showed an arrhythmia, whereas 16 (22%) demonstrated normal sinus rhythm. Four recordings (5%) were non-interpretable. From the 57 arrhythmic tracings, 44 distinct arrhythmic diagnoses were identified. Paroxysmal atrial fibrillation (AF) accounted for 16 episodes. Other diagnosed arrhythmias included atrial flutter (n = 6), paroxysmal supraventricular tachycardia (PSVT) (n = 4), premature atrial complexes (PAC) (n = 6), premature ventricular complexes (PVC) (n = 9), inappropriate sinus tachycardia (n = 12), and second-degree atrioventricular (AV) block type I (n = 4). Conclusions: Smartwatch-based ECG monitoring in symptomatic patients is feasible and provides a high diagnostic yield for a broad spectrum of arrhythmias. Unlike large-scale population screening approaches, which generate vast datasets with limited clinical benefit, a symptom-driven strategy applied to carefully selected, educated, and motivated patients proves both clinically valuable and organizationally sustainable. Indeed, the mean number of tracings transmitted per patient was low (1.3), confirming the clinical and operational sustainability of this patient-triggered, real-world approach. Full article

Background: Per- and polyfluoroalkyl substances (PFAS) represent a large class of synthetic fluorinated compounds characterized by highly stable carbon–fluorine bonds that confer exceptional environmental persistence and bioaccumulative properties. Although regulatory measures have restricted the production of several PFAS, including perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS), their environmental persistence continues to maintain widespread human exposure, while newly introduced replacement compounds raise additional toxicological concerns. Notably, the recent evidence demonstrating PFAS-induced alterations in key cardiac ion channel activity and electrocardiographic parameters suggest potential electrophysiological mechanisms that may contribute to arrhythmogenesis and cardiac arrhythmias including the most frequent one, atrial fibrillation (AF). Methods: We conducted a narrative literature review of experimental, epidemiological, and mechanistic studies investigating and reporting the cardiovascular, electrophysiological, and potential arrhythmogenic effects of PFAS. Results: Available evidence indicates that PFAS exposure is associated with alterations in cardiac electrophysiology, including modulation of ion channel activity (notably sodium, calcium, and potassium channels), disruption of calcium handling, and changes in electrocardiographic parameters such as QT interval prolongation, which are key contributors to arrhythmogenesis and AF. Conclusions: This review highlights the need for improved understanding of PFAS-induced electrophysiological alterations, to clarify the role of PFAS in cardiac arrhythmias including AF. Full article

Background/Objectives: Portable and wearable ECG technologies are increasingly used in adult cardiac monitoring. However, evidence supporting their feasibility and diagnostic performance in pediatric populations remains limited. This systematic review evaluates the diagnostic accuracy, usability, artifact susceptibility, and user acceptance of mobile ECG technologies in pediatric cardiology. Methods: A systematic literature search was performed in the Embase, PubMed, Scopus, and Web of Science databases. The review was conducted in accordance with the PRISMA 2020 guidelines and was registered in the PROSPERO database. Results: A total of 30 publications were included in the final analysis. Portable ECG devices demonstrated good feasibility diagnostic utility in children. Handheld systems provided high-quality tracings with strong agreement with standard 12-lead ECGs and higher adherence, as well as user satisfaction compared with conventional event recorders. However, automated rhythm classification frequently misidentified pediatric arrhythmias. Smartwatch-based ECG recordings showed high diagnostic accuracy when manually interpreted, but automated algorithms were unreliable, particularly for tachyarrhythmias and conduction abnormalities. Alternative electrode placement strategies improved smartwatch performance, and patient acceptance was consistently high. ECG patch monitoring, particularly with extended-wear devices, achieved the highest diagnostic yield, detecting arrhythmias often missed by short-duration Holter monitoring while maintaining comparable signal quality. Conclusions: Mobile ECG technologies represent a promising adjunct for pediatric rhythm surveillance, offering diagnostic performance comparable to standard modalities when interpreted by clinicians and improved usability and patient acceptance. Persistent limitations include the poor reliability of adult-oriented automated algorithms and the underrepresentation of younger children and the predominantly off-label use of these devices in pediatric populations, underscoring the need for pediatric-specific algorithm development and age-adapted device design. Full article

Accurate feature selection is critical for machine learning in medical diagnosis, yet conventional methods often fail to capture complex non-linear relationships in biomedical data. This study introduces an advanced feature selection approach that integrates distance correlation with adaptive weighting to enhance cardiac arrhythmia detection. The proposed method ranks features based on distance correlation, applies an inverse penalty weighting scheme to suppress highly correlated features while emphasizing moderately correlated ones, and incorporates RBF kernel transformation followed by LASSO refinement. Fifteen feature selection techniques were evaluated on an electrocardiographic database of 279 morphological and physiological features using 4-fold cross-validation with a neural network classifier. The proposed method outperformed all alternatives, including the best conventional approach, by effectively capturing non-linear dependencies, mitigating multicollinearity and overfitting, and leveraging synergistic kernel-based interaction modeling with sparse selection. These results demonstrate that combining statistical dependence measures, adaptive regularization, and non-linear transformations provides a robust framework for feature selection in cardiac arrhythmia classification and broader medical informatics applications. Full article

Kv11.1 (hERG1) channels, encoded by KCNH2, mediate the rapid delayed rectifier potassium current (I_Kr) crucial for cardiac repolarization. Disruptions, via mutations or antiarrhythmic drugs like dofetilide cause severe arrhythmogenic disorders, including Long QT Syndrome Type 2 (LQT2), Brugada Syndrome (BrS), and Torsades de Pointes (TdP). While Kv11.1’s role in channelopathies and drug-induced arrhythmias is established, understanding its complex regulation and therapeutic targeting remains a challenge. This review synthesizes the structural, functional, and regulatory aspects of Kv11.1 channels and their clinical implications. Recent studies using iPSC-derived cardiomyocytes highlight regulation by PI3K/Akt, PKC, and PKA signaling via phosphorylation (Ser283, Ser890) and interactions with proteins like 14-3-3. Beyond electrophysiology, Kv11.1 influences pathological hypertrophy and non-cardiac functions including insulin secretion. Pharmacological efforts focus on activators to shorten action potential duration and suppress TdP, and blockers with overdose risks. Mutation heterogeneity, exemplified by trafficking impairment (G785D) in LQT2 and gain-of-function (R397C) in BrS, complicates precision therapy. Clinically, systematic risk stratification using electrocardiographic parameters and genotype-specific approaches enables personalized management. Beta-blockers remain first-line therapy for LQTS2, while rigorous avoidance of QT-prolonging medications and electrolyte monitoring form the cornerstones of preventive care. Advancing Kv11.1-targeted therapies with approaches like CRISPR-Cas9 and pharmacological chaperones (e.g., lumacaftor) holds promise for personalized treatments, ultimately reducing arrhythmic events and sudden cardiac death. Full article

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. Full article

Background/Objectives: The Wolff–Parkinson–White (WPW) pattern is characterized by ventricular preexcitation due to an accessory atrioventricular pathway. Population-based data on the prevalence of asymptomatic WPW patterns in children are limited, and automated ECG interpretation may be misleading in the setting of preexcitation. Our aim was to determine the prevalence of the WPW pattern in a large cohort of asymptomatic Romanian school children and to describe electrocardiographic characteristics, ECG-based accessory pathway localization, and automated ECG interpretation errors. Methods: We performed a retrospective cross-sectional analysis of 12-lead ECGs obtained during a school-based screening program in Romania (May–December 2015). After exclusion of duplicates, technical errors, and participants outside the prespecified age range, 24,112 unique children aged 6–18 years were included. The WPW pattern was adjudicated by pediatric electrophysiologists. Prevalence was estimated using the Wilson score method. Sex differences were assessed using Fisher’s exact test. Results: The WPW pattern was identified in 18/24,112 children, yielding a prevalence of 0.075% (0.75 per 1000). The WPW pattern was more frequent in boys than girls (12/11,858 (0.10%) vs. 6/12,255 (0.048%), p = 0.18). Most cases demonstrated mild preexcitation, with only a minority showing marked QRS widening. ECG-based algorithms suggested a predominance of left-sided accessory pathways. Automated ECG interpretation frequently produced misleading diagnostic statements, including bundle branch block/intraventricular conduction delay (5/18; 27.8%) and pseudo-infarction/ischemia patterns (1/18; 5.6%), and did not explicitly identify WPW/preexcitation. Conclusions: In a large school-based screening cohort of asymptomatic Romanian children, WPW pattern prevalence was 0.074%, with a trend toward male predominance. Most cases exhibited mild preexcitation. Automated ECG interpretation commonly misclassified preexcitation-related ECG findings, highlighting the importance of expert ECG review in pediatric screening programs. Full article

Doxorubicin (DOX) is a widely used anthracycline, but its clinical use is limited by dose-dependent cardiotoxicity. This experimental study evaluated the cardioprotective potential of empagliflozin (EMPA) against DOX-induced cardiotoxicity. Thirty healthy adult rats were randomized into five groups (n = 6): control (group I), EMPA (group II), EMPA + DOX (group III), DOX (group IV), and EMPA-preconditioning + DOX (group V). EMPA was administered orally at 10 mg/kg/day, either concomitantly with DOX or as a 14-day preconditioning course. Cumulative DOX exposure reached 15 mg/kg to establish a reproducible cardiotoxicity model. Serial electrocardiograms (ECGs) were recorded, blood samples were collected, and hearts were harvested for detailed histopathological analysis. Compared with the control group, group IV demonstrated significant QT/QTc prolongation and repolarization abnormalities, marked troponin elevation, and characteristic histological lesions, including cardiomyocyte vacuolization, loss of striations, diffuse inflammation, myocyte atrophy, and increased fibrosis. In groups receiving EMPA with DOX exposure (groups III and V), ECG changes were attenuated, troponin elevation was lower, and structural myocardial damage was substantially reduced, with better preservation of cardiomyocyte architecture and less fibrosis. These results suggest that EMPA provides significant cardioprotection against DOX-induced cardiotoxicity in rats, supporting further investigation of SGLT2 inhibitors in cardio-oncology. Full article

Flexible electrode materials with tailored electrical and mechanical properties are essential for reliable electrocardiographic (ECG) sensing. In this work, p-toluenesulfonic-acid-doped polypyrrole (PPy–TSA) films were modified using polymeric and inorganic fillers, as well as their combinations (polyethylene glycol, graphene, carbon nanotubes, and zeolite), to tune their functional performance. The reference PPy–TSA film exhibits typical morphological and chemical characteristics of doped polypyrrole and serves as a reliable baseline for comparison. All composite films retain electrical conductivity within the range required for ECG applications while showing improved mechanical compliance (i.e., enhanced ability to conform to the skin and sustain deformation). Based on the optimized balance between electrical and mechanical properties, flexible ECG electrodes were fabricated using the TSA-doped PPy-based composite film. ECG recordings obtained with the several proposed electrodes show good agreement with those acquired using a commercial ECG electrode, demonstrating the potential of PPy-based composite films for flexible bioelectronic sensing applications. Full article

Diabetes mellitus is projected to affect more than 1.3 billion people worldwide by 2050, with millions remaining undiagnosed or in a prediabetic state. Cardiovascular complications account for nearly half of diabetes-related deaths, highlighting the need for scalable tools capable of identifying metabolic dysregulation before irreversible cardiac damage develops. This review synthesizes current mechanistic, clinical, and computational evidence linking diabetes to cardiac electrophysiological remodeling and examines electrocardiography (ECG) as a non-invasive modality for early detection of dysglycaemia. Chronic hyperglycaemia, insulin resistance, oxidative stress, microvascular dysfunction, and cardiac autonomic neuropathy collectively contribute to measurable ECG alterations, including QT/QTc prolongation, increased QT dispersion, changes in Tp–e indices, and reduced heart rate variability. These changes often precede overt cardiovascular disease and correlate with glycaemic burden and diabetes duration. Recent advances in signal processing and artificial intelligence have expanded the diagnostic potential of ECG. Both classical machine learning approaches and large-scale deep learning models demonstrate that ECG contains latent signatures associated with incident type 2 diabetes and glycaemic status. Despite promising results, heterogeneity in study design, limited representation of prediabetes, and lack of standardized validation frameworks remain major barriers to clinical translation. Prospective, multi-ethnic studies are needed to establish ECG-based screening as a reliable component of early diabetes detection strategies. Full article

Background: Opioid dependence treated with buprenorphine/naloxone is associated with increased cardiovascular risk; however, data regarding aortic elasticity and cardiac electrophysiological balance during long-term maintenance therapy remain limited. This study investigated aortic stiffness and distensibility in individuals receiving buprenorphine/naloxone (Suboxone), and examined their associations with echocardiographic and electrocardiographic parameters, including the index of cardiac electrophysiological balance (iCEB and iCEBc). Methods: A retrospective cohort analysis was conducted, including 130 intravenous opioid users receiving Suboxone and 150 age- and sex-matched healthy controls. All participants underwent clinical evaluation, transthoracic echocardiography, resting 12-lead electrocardiography, and 24-h ambulatory blood pressure monitoring. Results: Compared to controls, opioid users demonstrated significantly higher aortic distensibility (median 0.019 vs. 0.015, p < 0.001) and lower aortic stiffness (median 52.31 vs. 64.66, p < 0.001). Patients receiving Suboxone for more than 18 months exhibited higher diastolic blood pressure (p = 0.044), mean arterial pressure (p = 0.046), and pulmonary artery pressure (p = 0.022). Aortic elasticity indices showed strong correlations with blood pressure and echocardiographic parameters. In the overall cohort, Suboxone use duration was not significantly correlated with aortic stiffness or distensibility parameters, while a weak negative correlation was observed with ferritin levels (r = −0.231, p = 0.008). In subgroup analysis of long-term users (>18 months), a moderate positive correlation was observed between therapy duration and iCEB values (r = 0.367, p = 0.001). Conclusions: Chronic buprenorphine/naloxone therapy appears to be associated with changes in aortic elasticity, blood pressure, and mild electrophysiological alterations. These results support the use of non-invasive vascular and electrocardiographic evaluations for cardiovascular risk monitoring and stratification among patients receiving opioid maintenance therapy. Full article

Background: Few studies have reported electrocardiogram data collected during the neonatal period. The aim of this study was to evaluate electrocardiographic parameters in healthy neonates during the first postnatal hour. Methods: Electrocardiogram samples taken during the first hour of life from newborns born at our hospital were analyzed in this prospective observational study. Demographic data and possible electrocardiogram changes were studied. The results were statistically analyzed. Results: A total of 260 patients were included during the study period. Among these, 50% were male (n = 130), the mean gestational age was 38.1 ± 1.4 weeks, and the mean birth weight was 3.2 ± 1.4 kg. In the electrocardiograms obtained, low atrial rhythm was detected in 0.3% of the patients (n = 1). Right axis deviation was observed in 1.5% of the patients (n = 4), and left axis deviation was observed in 1.2% of the patients (n = 3). An abnormal P-axis was found in one patient (0.3%), and an abnormal QRS-T angle was found in one patient (0.3%). No statistically significant differences were observed in the other parameters. Conclusion: Physiologic electrocardiographic findings can be observed during the first postnatal hour. Further studies are needed to clarify the interpretation of the electrocardiogram findings. Full article