Search Results (45)

Exercise stress testing remains one of the most widely used and cost-effective diagnostic tools in clinical cardiology. Beyond the traditional evaluation of induced ischemia, it provides valuable information on functional capacity, blood pressure response and arrhythmic behavior during exercise. In particular, the test plays a crucial role in assessing and interpreting exercise-induced arrhythmias, including tachyarrhythmias, such as premature ventricular beats (PVBs) and bradyarrhythmias, as well as corroborating the suspicion of some ion channel diseases. The usefulness of exercise testing is also highlighted in patients with devices, where it can help evaluate their function and exercise adaptation, as well as in specific conduction disorders, such as Wolff–Parkinson–White syndrome. This practical guide summarizes the key aspects of performing and interpreting the exercise stress test, focusing on hemodynamic and arrhythmic findings and their clinical implications, and includes several illustrative clinical cases. Full article

Accurate detection of premature atrial contractions (PACs) and premature ventricular contractions (PVCs) in single-lead electrocardiograms (ECGs) is crucial for early identification of patients at risk for atrial fibrillation, cardiomyopathy, and other adverse outcomes. In this work, we present a fully convolutional one-dimensional U-Net that reframes beat classification as a segmentation task and directly detects normal beats, PACs, and PVCs from raw ECG signals. The architecture employs a ConvNeXt V2 encoder with simple decoder blocks and does not rely on explicit R-peak detection, handcrafted features, or fixed-length input windows. The model is trained on the Icentia11k database and an in-house single-lead ECG dataset that emphasizes challenging, noisy recordings, and is validated on the CPSC2020 database. Generalization is assessed across several benchmark and clinical datasets, including MIT-BIH Arrhythmia (ADB), MIT 11, AHA, NST, SVDB, CST STRIPS, and CPSC2020. The proposed method achieves near-perfect QRS detection (sensitivity and precision up to 0.999) and competitive PVC performance, with sensitivity ranging from 0.820 (AHA) to 0.986 (MIT 11) and precision up to 0.993 (MIT 11). PAC detection is more variable, with sensitivities between 0.539 and 0.797 and precisions between 0.751 and 0.910, yet the resulting F1-score of 0.72 on SVDB exceeds that of previously published approaches. Model interpretability is addressed using Layer-wise Gradient-weighted Class Activation Mapping (LayerGradCAM), which confirms physiologically plausible attention to QRS complexes for PVCs and to P-waves for PACs. Overall, the proposed framework provides a robust, interpretable, and hardware-efficient solution for joint PAC and PVC detection in noisy, single-lead ECG recordings, suitable for integration into Holter and wearable monitoring systems. Full article

Background/Objectives: Non-dilated left ventricular cardiomyopathy (NDLVC) is a recently defined clinical entity associated with increased risk of ventricular arrhythmias (VA) and sudden cardiac death (SCD), despite preserved LV geometry. The role and temporal variability of noninvasive electrocardiographic (ECG) risk markers in this population remain insufficiently characterized. To assess the temporal variability of ECG-derived risk markers in patients with NDLVC and explore their association with major adverse cardiac events, including heart failure (HF) and VA hospitalization. Methods: We prospectively studied 55 patients with NDLVC who underwent cardiac magnetic resonance imaging and serial 24 h Holter monitoring, signal-averaged ECG, and standard 12-lead ECG over a one-year period. Patients were followed up for 39.5 ± 8.6 months. Nine ECG-based risk markers were analyzed, including premature ventricular contraction (PVC) burden, non-sustained ventricular tachycardia (NSVT) occurrence, its maximum rate and maximum beats, mean QTc interval, standard deviation of NN intervals (SDNN), deceleration capacity (DC), heart rate turbulence onset and slope (TO/TS), T-wave alternans (TWA), and late potentials. Clinical outcomes were HF and VA hospitalization. Logistic regression was used to evaluate associations between changes in ECG parameters and outcomes. Results: A change (from positive to negative and vice versa) in at least one ECG parameter was detected in 67.3% of patients, with the highest variability observed in TWA (34.5%), NSVT (23.6%), and PVC burden (23.6%). Despite this variability, only SDNN was significantly associated with increased risk of VA hospitalization during follow-up (OR = 0.98, 95% CI: 0.97–0.99, p = 0.006). No ECG changes were associated with HF hospitalization. Conclusions: Patients with NDLVC exhibit substantial temporal variability in noninvasive ECG risk markers. While most changes do not correlate with clinical events, an inverse association was found between SDNN and VA risk. These findings support the ongoing evaluation and the necessity to identify more effective risk stratification markers in this subgroup of patients. Full article

Background: The widespread use of cardiac magnetic resonance imaging (MRI) in clinical practice has enabled the identification of numerous patients with evident damage from previous myocarditis, whether known or unknown. For years, myocardial fibrosis has been a topic of interest due to its established correlation with arrhythmic events in various clinical settings, including ischemic heart disease, dilated cardiomyopathy, and hypertrophic cardiomyopathy. MIBG scintigraphy is a method widely used in patients who are candidates for defibrillator implantation or have experienced heart failure. This examination evaluates the sympathetic innervation of the myocardium. Objective: To assess the real arrhythmogenic risk of non-ischemic scars identified in symptomatic or asymptomatic patients through the use of MIBG. Methods: Patients were retrospectively selected based on the presence of non-ischemic myocardial fibrosis detected by cardiac MRI, consistent with a myocarditis outcome (even in the absence of a clear history of myocarditis). These patients underwent myocardial scintigraphy with MIBG using a tomographic technique. Results: A total of 50 patients (41 males, mean age 51 ± 16 years) who underwent MRI from 2019 to June 2024 were selected. The primary indication for MRI was ventricular ectopic extrasystoles detected on Holter ECG (n = 12, 54%), while five patients underwent MRI following a known acute infectious event (23%, including three cases of COVID-19 infection). All symptomatic patients presented with chest pain in the acute phase, accompanied by elevated hsTNI levels (mean value: 437 pg/mL). The MRI findings showed normal ventricular volumes (LV: 80 mL/m², RV: 81 mL/m²) and normal ejection fractions (56% and 53%, respectively). The mean native T1 mapping value was 1013 ms (normal range: 950–1050). T2 mapping values were altered in the 5 patients who underwent MRI during the acute phase (mean value: 57 ms), without segmentation. Additionally, three patients had non-tamponade pericardial effusion. All patients exhibited LGE (nine subepicardial, seven midwall, six patchy). All patients underwent myocardial scintigraphy with MIBG at least 6 months after the acute event, with only one case yielding a positive result. This patient, a 57-year-old male, had the most severe clinical presentation, including more than 65,000 premature ventricular beats (PVBs) and multiple episodes of paroxysmal supraventricular tachycardia (PSVT) recorded on Holter ECG. MRI findings showed severe left ventricular dysfunction, a slightly dilated LV, and midwall LGE at the septum, coinciding with hypokinetic areas. Conclusions: MIBG scintigraphy could be a useful tool in assessing arrhythmic risk in patients with previous myocarditis. It could help reduce the clinical burden of incidental findings of non-ischemic LGE, which does not appear to be independently associated with an increased risk profile. Full article

In veterinary medicine, hyperbaric oxygen chamber treatment (HBOT) is gaining popularity. Therefore, an increasing number of patients referred for this therapy are being recorded, mainly due to ischemic events, wound healing support, and a high risk of reperfusion damage. During the HBOT procedure, several changes occur in the body’s micro- and macroenvironments. This study involved 34 dogs of various ages and health statuses. The atmospheric conditions in the test hyperbaric chamber included a pressure of 1.5 atmosphere absolute (ATA) at 100% oxygenation. The individuals were divided into three groups: (1) individuals with degenerative mitral valve disease (DMVD), (2) individuals with diseases other than cardiac issues, and (3) healthy individuals who qualified for the HBOT procedure. The period of measurement using the Holter apparatus was divided into four stages: 30 min before the subject’s placement in the hyperbaric chamber; a 4-min compression period (setting chamber conditions); a 90 min HBOT period; and a 1 min decompression period of the hyperbaric chamber. During the HBOT, there was a statistically significant decrease in heart rate in groups 2 and 3 compared to group 1. The heart rate in group 1 remained unchanged through every period of the study. In addition, some of the dogs developed respiratory arrhythmia; in two dogs, premature ventricle beats occurred. The changes observed during the ventricular period indicate that the HBOT procedure causes a significant change in heart rate in dogs without cardiac diseases. Full article

A 67-year-old man started treatment due to frequent asymptomatic premature ventricular complexes (PVCs) accidentally being registered during a preventive examination by a specialist, because of which he was referred to cardiologist. During the initial 24-hour (h) ECG monitoring, 4.5% PVCs and one episode of asymptomatic non-sustained ventricular tachycardia (NSVT) with three PVCs in row, at a frequency of 150 beats per minute (bpm), were detected. After the introduction of beta blockers into therapy, a lower number of PVCs, without NSVT, were recorded in the control 24 h Holter ECG, while transthoracic echocardiography (TTE) showed normal left ventricular (LV) systolic function without cardiomyopathy. So, an exercise test was indicated, and it was interrupted in the third minute at 120 beats per minute (bpm) due to fatigue and pain in the hips, without malignant arrhythmias, angina or dyspneic complaints. During the rest period, a significant inferolateral depression of the ST junction was observed, which recovered in the ninth minute. Immediately after the ECG monitoring stopped, the patient lost consciousness; his pulse was not palpable, but breathing was audible, so cardiac massage was started. After he had regained consciousness, the ECG showed alternating sinus and junctional rhythm with the lowest frequency of 33 bpm, which was accompanied by marked hypotension (80/50 mmHg). The patient was immediately hospitalized; coronary angiography and repeated TTE were completely normal, while continuous ECG monitoring did not confirm malignant rhythm disorders or asystole. It was concluded that it was vasovagal syncope (VVS), most likely caused by the Bezold–Jarisch reflex (BJR). Full article

Background: Over the last five decades, a fair number of echocardiographic studies have evaluated the prevalence of mitral valve prolapse (MVP) in various cohorts of individuals, including heterogeneous study populations. The present systematic review has been primarily designed to summarize the main findings of these studies and to estimate the overall MVP prevalence in the general community. Methods: All echocardiographic studies assessing the MVP prevalence in various cohorts of individuals, selected from PubMed and EMBASE databases, were included. There was no limitation of time period. The risk of bias was assessed by using the National Institutes of Health (NIH) Quality Assessment Tool for Observational Cohort and Cross-Sectional Studies. Results: The full texts of 21 studies with 1354 MVP individuals out of 63,723 participants were analyzed. The overall pooled prevalence of MVP was 4.9% (range of 0.6–21%). When dividing the studies in two groups according to the echocardiographic criteria used for MVP diagnosis (less specific old criteria or more specific new criteria, respectively), the estimated pooled prevalence of MVP was 7.8% (range of 2–21%) for the older studies (performed between 1976 and 1998) and 2.2% (range of 0.6–4.2%) for the more recent ones (conducted between 1999 and 2021). Potential selection bias, hospital- or referral-based series, and the use of less specific echocardiographic criteria for MVP diagnosis have been indicated as the main reasons for the higher MVP prevalence detected by the older studies. MVP was commonly associated with a narrow antero-posterior thoracic diameter, isolated ventricular premature beats and nonspecific ST-T-wave abnormalities on a resting electrocardiogram, mild-to-moderate mitral regurgitation (MR), the reduced probability of obstructive coronary artery disease, and a low frequency of serious complications, such as severe MR, infective endocarditis, heart failure, stroke, and atrial fibrillation. Conclusions: MVP has a low prevalence in the general population, regardless of age, gender, and ethnicity, and is associated with a good outcome. Full article

Objectives: Arterial hypertension (AH) is one of the major risk factors for cardiovascular diseases. An association between untreated AH and arrhythmia is observed. Cardiac magnetic resonance (CMR) assesses myocardial fibrosis by detecting foci of late gadolinium enhancement (LGE). Clinical significance of LGE at the right ventricular insertion point (RVIP) is not fully established. This study aimed to assess the relationship between the presence of LGE at the RVIP determined by CMR and the incidence of arrhythmia in a group suffering from arterial hypertension. Methods: The study group consisted of 81 patients with AH (37 men and 44 women, age: 56.7 ± 7.1 years). All subjects underwent CMR and 24 h Holter ECG monitoring. Two subgroups were distinguished in the study group based on the criterion of the presence of LGE at the RVIP in CMR. The RVIP+ subgroup consisted of patients with LGE at the RVIP, while the RVIP− group consisted of patients without LGE at the RVIP. Results: The RVIP+ subgroup was characterized by higher maximum and minimum heart rates in 24 h Holter ECG recordings compared to the RVIP− subgroup (p < 0.05). The RVIP+ subgroup had a statistically significantly higher number of single premature supraventricular beats, supraventricular tachycardias, and single premature ventricular beats than the RVIP− subgroup (p < 0.05). Regression analysis documented that a longer duration of AH (counted from diagnosis) as well as the occurrence of LGE at the RVIP (assessed by CMR) are independent risk factors for arrhythmia (p < 0.05). Conclusions: Due to the possibility of detecting LGE at the RVIP, CMR may be a useful diagnostic method in estimating the risk of arrhythmias in the group of patients with AH. Full article

Objectives: this study aims to evaluate the prevalence of various arrhythmias and other electrocardiographic patterns within the group of individuals with overweight and obesity. Methods: One hundred eighty-one adults (90 females and 91 males) were qualified for inclusion in the experimental group. All participants had a body mass index (BMI) exceeding 25 kg/m² (98 patients with obesity and 83 with overweight). The mean BMI in the obesity group was 33.6 kg/m², and all participants had class 1 obesity. The control group comprised 69 individuals (56 females and 13 males) with normal BMI. The basic measurements were performed, and the participants filled out questionnaires describing their health conditions and lifestyles. Each participant underwent an electrocardiographic (ECG) examination and a 24 h Holter ECG examination. Results: In patients with class 1 obesity compared to the control patients, the average numbers of premature ventricular beats (PVBs) and premature supraventricular beats (SPBs) were statistically significantly higher (p = 0.030 and p = 0.042). There was a positive correlation between body weight and PVB (p = 0.028) and between body weight and SPB (p = 0.028). Moreover, BMI and waist circumference were correlated with SPB (p = 0.043 and p = 0.031). In the backward stepwise multivariate regression model considering 24 h Holter ECG monitoring, concerning SPB as the dependent variable, it was observed that BMI (especially obesity class 1), type 2 diabetes, and thyroid disease exhibited the highest regression coefficients. Conclusions: obesity, even in class 1, might be a factor in a more frequent occurrence of abnormalities in electrocardiographic tests. Full article

The aim of this study was to observe electric cardiac activity in real working conditions, with the application of Holter and the electrocardiogram in search and rescue dogs. Thirty-one handlers of search and rescue dogs voluntarily participated in this study. Nine dogs were selected to wear the Holter, and twenty-three were submitted to electrocardiographic recordings (one dog, excluded by Holter examination, was then included in the ECG group). Our results showed few cardiac rhythm alterations, such as escape beats, premature ventricular beat, and depression and elevation of the ST segment, particularly during the working phase in the Holter group and during recovery time immediately after activity in the electrocardiographic group. Detected alterations in real working conditions may provide more information than routine checks, and Holter monitoring can be more functional. However, not all dogs tolerate wearing the Holter harness, and more time is thus needed to apply the equipment. In addition, the results are not immediate, and the absence of water is essential because it would damage the equipment. Full article

Heart failure (HF) represents a significant global health challenge that is still responsible for increasing morbidity and mortality despite advancements in pharmacological treatments. This review investigates the effectiveness of non-pharmacological interventions in the management of HF, examining lifestyle measures, physical activity, and the role of some electrical therapies such as catheter ablation, cardiac resynchronization therapy (CRT), and cardiac contractility modulation (CCM). Structured exercise training is a cornerstone in this field, demonstrating terrific improvements in functional status, quality of life, and mortality risk reduction, particularly in patients with HF with reduced ejection fraction (HFrEF). Catheter ablation for atrial fibrillation, premature ventricular beats, and ventricular tachycardia aids in improving left ventricular function by reducing arrhythmic burden. CRT remains a key intervention for selected HF patients, helping achieve left ventricular reverse remodeling and improving symptoms. Additionally, the emerging therapy of CCM provides a novel opportunity for patients who do not meet CRT criteria or are non-responders. Integrating non-pharmacological interventions such as digital health alongside specific medications is key for optimizing outcomes in HF management. It is imperative to tailor approaches to individual patients in this diverse patient population to maximize benefits. Further research is warranted to improve treatment strategies and enhance patient outcomes in HF management. Full article

Cardiac dysfunction induced by premature ventricular complexes (PVCs) is relatively controversial and challenging to detect in the early stage. In this observational study, we retrospectively analyzed the cardiopulmonary exercise test (CPET) data of 94 patients with frequent premature ventricular beats (47 males, 49.83 ± 13.63 years) and 98 participants (55 males, 50.84 ± 9.41 years) whose age and gender were matched with the patient with PVCs. The baseline information and routine echocardiography detection were recorded on admission. PVCs were diagnosed by 24 h Holter monitoring, and cardiorespiratory capacity was assessed using peak oxygen uptake (V’O₂peak), anaerobic threshold (AT), and other CPET parameters with an individualized bicycle ramp protocol according to the predicted workload and exercise situation of each participant. There were no statistically significant differences in most baseline characteristics between the two groups. Indicators that reflect cardiopulmonary capacity, such as V’O₂peak, AT, and ΔO2 pulse/Δwork rate(ΔV’O₂/ΔWR), were all significantly lower in the PVC group (p = 0.031, 0.021, and 0.013, respectively) despite normal and nondiscriminatory left ventricular ejection fractions between the two groups. However, there was no statistically significant difference among subgroups based on the frequency of PVCs, which was <10,000 beats/24 h, 10,000–20,000 beats/24 h, and >20,000 beats/24 h. The cardiorespiratory capacity was lower in patients with frequent PVCs, indicating that CPET could detect early signs of impaired cardiac function induced by PVCs. Full article

With an aging population and increased chronic diseases, remote health monitoring has become critical to improving patient care and reducing healthcare costs. The Internet of Things (IoT) has recently drawn much interest as a potential remote health monitoring remedy. IoT-based systems can gather and analyze a wide range of physiological data, including blood oxygen levels, heart rates, body temperatures, and ECG signals, and then provide real-time feedback to medical professionals so they may take appropriate action. This paper proposes an IoT-based system for remote monitoring and early detection of health problems in home clinical settings. The system comprises three sensor types: MAX30100 for measuring blood oxygen level and heart rate; AD8232 ECG sensor module for ECG signal data; and MLX90614 non-contact infrared sensor for body temperature. The collected data is transmitted to a server using the MQTT protocol. A pre-trained deep learning model based on a convolutional neural network with an attention layer is used on the server to classify potential diseases. The system can detect five different categories of heartbeats: Normal Beat, Supraventricular premature beat, Premature ventricular contraction, Fusion of ventricular, and Unclassifiable beat from ECG sensor data and fever or non-fever from body temperature. Furthermore, the system provides a report on the patient’s heart rate and oxygen level, indicating whether they are within normal ranges or not. The system automatically connects the user to the nearest doctor for further diagnosis if any critical abnormalities are detected. Full article

Trypanosoma cruzi infection causes inflammation and fibrosis, resulting in cardiac damage in dogs. The objectives of this study were to describe cardiac magnetic resonance imaging (CMR) in naturally infected dogs with chronic Chagas disease and the frequency of abnormalities for CMR and cardiac diagnostic tests. Ten asymptomatic, client-owned dogs seropositive for T. cruzi were prospectively enrolled in an observational study evaluating echocardiography, ECG (standard and ambulatory), cardiac troponin I (cTnI), and CMR. Standard ECG measurements (3/10) and cTnI concentration (1/10) outside the reference range were uncommon. Ambulatory ECG abnormalities were documented more frequently (6/10 dogs) than with standard ECG and included ventricular arrhythmias (4), supraventricular premature beats (3), second-degree atrioventricular block (2), and sinus arrest (1). Echocardiographic abnormalities were documented in 6/10 dogs including mildly increased left ventricular internal dimension in diastole (1) and decreased right ventricular (RV) systolic function based on reductions in tricuspid annular plane systolic excursion (3) and RV S’ (4). Abnormalities were detected with CMR in 7/10 dogs including delayed myocardial enhancement in 5 of which 2 also had increased extracellular volume, abnormal wall motion in 5, and loss of apical compact myocardium in 1. In conclusion, CMR abnormalities were common, and the results of this study suggest CMR can provide useful information in dogs with T. cruzi infection and may support naturally infected dogs for future clinical investigation as an animal model for Chagas disease. Full article

Wilson assumed that the ventricular gradient (VG) is independent of the ventricular activation order. This paradigm has often been refuted and was never convincingly corroborated. We sought to validate Wilson’s concept by intra-individual comparison of the VG of sinus beats and ectopic beats, thus assessing the effects of both altered ventricular conduction (caused by the ectopic focus) and restitution (caused by ectopic prematurity). We studied standard diagnostic ECGs of 118 patients with accidental extrasystoles: normally conducted supraventricular ectopic beats (SN, N = 6) and aberrantly conducted supraventricular ectopic beats (SA, N = 20) or ventricular ectopic beats (V, N = 92). In each patient, we computed the VG vectors of the predominant beat, $\overrightarrow{V{G}_p}$, of the ectopic beat, $\overrightarrow{V{G}_e}$, and of the VG difference vector, $\overrightarrow{\Delta V{G}_{ep}}$, and compared their sizes. $\left|\overrightarrow{V{G}_e}\right|$ of the SA and V ectopic beats were significantly larger than $\left|\overrightarrow{V{G}_p}\right|$ (53.7 ± 25.0 vs. 47.8 ± 24.6 mV∙ms, respectively; p < 0.001). $\left|\overrightarrow{\Delta V{G}_{ep}}\right|$ were three times larger than the difference of $\left|\overrightarrow{V{G}_e}\right|$ and $\left|\overrightarrow{V{G}_p}\right|$ (19.94 ± 9.76 vs. 5.94 mV∙ms, respectively), demonstrating differences in the $\overrightarrow{V{G}_p}$ and $\overrightarrow{V{G}_e}$ spatial directions. The amount of ectopic prematurity was not correlated with $\left|\overrightarrow{\Delta V{G}_{ep}}\right|$, although the larger VG difference vectors were observed for the more premature (<80%) extrasystoles. Electrical restitution properties and electrotonic interactions likely explain our findings. We conclude that the concept of a conduction-independent VG should be tested at equal heart rates and without including premature extrasystoles. Full article