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Because when fed to an on-line computer the ECG information carries a good deal of noise, of prime importance is devising a method for representation and filtration of the useful asignal. It is shown that in order to separate the ueful signal with a protracted direct ECG input from the patient to a computer the use of the proposed modified method of coherent accumulation is advisable. This modification envisages a step-wise solution of the following problems: current diagnosis of arrhythmic contractions exclusion of arrhythmic contractions from the accumulation procedure, automatic search of the normal duration of the RR intervals, equalization of the RRh intervals duration, statistical averaging of the obtained quantum values. The devised modification of the coherent accumulation method, while considerably increasing the noise-immunity of the algorhythm, enables it to effect a direct long-term automatic analysis of the ECG at intensive care units. The identification and measurement of the ECG waves and intervals are done through and automatic selection of the curve elements search zones, finding local maxima and also of the commencement and end of waves by using the method of the "moving window" with an adaptive evaluation of the first signal derivative intensity.
The clinical effect of the beta-adrenergic blocking drug acebutolol hydrochloride (SECTRAL) was studied in 18 patients with angina pectoris. Ambulatory 24-h ECG monitoring proved to be a useful method for assessing the efficacy of this drug in individual patients in their own daily stresses and environment. Patients were studied in the control state, after two weeks' treatment with placebo, and after two weeks' constant oral dose of the drug. It was found that acebutolol produced a significant decrease in ischemic ST segment depression in patients in whom good beta-blockade was achieved. The drug was less effective in patients in whom the heart rate response to exercise was not suppressed and in those with critical coronary artery obstructions.
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BACKGROUND: Left bundle branch area pacing (LBBAP) may restore a more physiological pattern of ventricular activation in patients with conduction delay; however, QRS narrowing alone may incompletely characterize electrical resynchronization. Ultra-high-frequency ECG (UHF-ECG) provides quantitative markers of ventricular activation timing and dyssynchrony. OBJECTIVE: To quantify paired OFF-to-ON changes in conventional ECG and UHF-ECG metrics during LBBAP in patients with baseline wide QRS and to assess the relationship between paced R-wave peak time (RWPT) and residual UHF-ECG dyssynchrony. METHODS: In this prospective single-center paired study, 21 patients with bradycardia and baseline wide QRS underwent standard ECG and UHF-ECG assessment during intrinsic rhythm (pacing OFF) and during LBBAP (pacing ON). Endpoints included QRS duration, signed VED16, absolute VED16 (|VED16|), mean ventricular delay (meanVD), and a clinically interpretable distance-to-normal metric defined as dist = max(|VED16|-20, 0). Paired changes were summarized as medians with bootstrap 95% confidence intervals and tested using the Wilcoxon signed-rank test. Associations between paced RWPT and residual dyssynchrony during pacing were evaluated using Pearson and Spearman correlation coefficients. RESULTS: LBBAP significantly narrowed QRS duration from 136.8 [130.2-153.6] ms during intrinsic rhythm to 116.0 [107.8-125.6] ms during pacing (median Δ -21.0 ms; 95% CI -33.9 to -18.6; p < 0.001). Signed VED16 did not change significantly (median Δ 0.4 ms; p = 1.000), consistent with the mixed conduction-phenotype composition of the cohort. In contrast, severity-oriented UHF-ECG endpoints improved: |VED16| decreased numerically (median Δ -5.2 ms; p = 0.070), whereas dist decreased significantly (median Δ -0.7 ms; 95% CI -14.4 to 0.0; p = 0.015). The proportion of patients within the normal dyssynchrony band (|VED16| ≤ 20 ms) increased from 7/21 (33.3%) to 12/21 (57.1%). Median paced RWPT was 66.6 [58.6-74.6] ms, and shorter RWPT correlated with lower residual |VED16| during pacing (Pearson r = -0.45, p = 0.038). CONCLUSIONS: In patients with baseline wide QRS, LBBAP produces marked QRS narrowing, whereas UHF-ECG provides complementary quantification of residual electrical dyssynchrony. Severity-oriented UHF-ECG endpoints, particularly a distance-to-normal metric, may offer an interpretable mechanistic framework beyond conventional ECG alone. Shorter paced RWPT was associated with lower residual dyssynchrony during pacing, supporting physiological coherence between procedural and high-resolution electrocardiographic markers.
BACKGROUND: Accurate interpretation of high-risk acute coronary syndrome (ACS) electrocardiograms (ECGs) is essential for early diagnosis and timely reperfusion, yet substantial deficits persist across health care professions. Digital self-learning formats such as FOAMed (Free Open Access Medical Education) are widely used, but their effectiveness has rarely been evaluated for complex, high-risk ACS ECG patterns. Existing ECG education studies often focus on students or single professional groups and established ST-segment elevation myocardial infarction (STEMI) criteria, leaving newer guideline-recognized STEMI equivalents, selected emerging occlusion myocardial infarction (OMI)-related patterns, and interprofessional emergency care underrepresented. OBJECTIVE: This study aimed to compare the effectiveness of FOAMed podcast and videos versus traditional print-based materials for teaching high-risk ACS ECG patterns and related clinical decision-making in emergency providers. METHODS: We conducted a prospective, interprofessional, controlled mixed methods trial across 5 training sites in Germany. Paramedics, prehospital emergency physicians, and emergency department clinicians received either a FOAMed multimedia module or print-based materials through concealed allocation; deviations from the intended 1:1 ratio resulted from participant no-shows. The intervention consisted of a 30-minute supervised self-learning session. In total, 103 participants were allocated to FOAMed (n=45) or print-based materials (n=58). Two coprimary outcomes were assessed: ECG interpretation accuracy and text-based ACS clinical decision-making. Secondary outcomes included subjective confidence, learning experience, and exploratory qualitative free-text responses. Outcome assessment was automated and blinded; mixed ANOVA was the primary analysis. The study was not prospectively registered because it assessed educational outcomes in health care professionals rather than patient health outcomes. RESULTS: All 103 participants completed the study. Both groups improved, with greater gains in the FOAMed group: ECG interpretation increased from 55% to 65.5% and text-based ACS clinical decision-making from 45% to 68%, versus 57% to 60% and from 47% to 63%, respectively, in the print-based group. Effect sizes were η²=0.055 for ECG interpretation and η²=0.044 for clinical decision-making. Exploratory subgroup analyses provided no evidence of differential effects across age, gender, or professional background and were likely underpowered. Qualitative responses (46 and 37 entries) provided contextual insights into perceived clarity, engagement, and practical relevance supporting the quantitative findings. CONCLUSIONS: This study is innovative in directly comparing a curated FOAMed multimedia module with selected print-based materials in an interprofessional emergency care population. It differs from existing research by focusing on subtle, emerging ischemic patterns and evaluating realistic, time-limited self-learning formats. The findings provide evidence that curated FOAMed resources can produce greater short-term improvements in ECG interpretation and text-based ACS clinical decision-making than traditional print-based materials in this setting. Although implications for clinical performance remain hypothetical, concise, high-quality digital modules may represent a practical supplement to structured continuing education in emergency care.
BACKGROUND: We aimed to refine and validate a deep neural network model from the ECG to predict atrial fibrillation (AF) risk, using samples from diverse backgrounds: the Framingham Heart Study (FHS), UK Biobank, and Estudo Longitudinal da Saúde do Adulto (ELSA-Brasil). We compared the model's performance to the clinical Cohorts for Heart and Aging Research in Genomic Epidemiology consortium (CHARGE-AF) risk score and evaluated the association with other cardiovascular outcomes. METHODS: The ECG-derived deep-learning prediction of AF (ECG-AF) model was refined using 60% of FHS samples free of AF. Its performance was then tested in the remaining FHS samples, UK Biobank, and ELSA-Brasil, with discrimination assessed by the area under the receiver operating characteristic curve. The association of ECG-AF with cardiovascular outcomes was assessed using Cox proportional hazards models. RESULTS: The study sample included 10 097 FHS participants (mean age 53±12 years; 54.9% women), 49 280 participants from the UK Biobank (mean age 64±8 years, 47.9% women), and 12 284 participants from ELSA-Brasil (mean age 53±8 years, 54.7% women). The ECG-AF model showed moderate discrimination for incident AF (area under the curve, 0.82 [95% CI, 0.80-0.84]) in the FHS, comparable to the CHARGE-AF score (area under the curve, 0.83 [95% CI, 0.81-0.85]), and incremental when combined (area under the curve, 0.85 [95% CI, 0.83-0.87]). In UK Biobank and ELSA-Brasil, combining ECG-AF and CHARGE also improved prediction. Higher ECG-AF scores were associated with increased risks of heart failure, myocardial infarction, stroke, and all-cause mortality in all 3 cohorts. CONCLUSIONS: In multinational cohort studies, the single-input ECG-AF deep neural network model demonstrated good performance in predicting AF and other cardiovascular outcomes, comparable to a multivariable clinical risk score, with improved performance when combined.
This study evaluated the reproductive performance and clinical safety of a novel recombinant eCG (r-eCG) in ewes. Two weeks prior to study onset (Day 0: intravaginal progesterone device insertion), 45 ewes were randomly assigned to negative control (NC; no eCG; n = 10), positive control (PC; 400IU commercial non-recombinant eCG; n = 20), or treatment group (T; 400IU r-eCG; n = 15). Ewes were inseminated with fresh-diluted semen (200 × 106 sperm). Ultrasonography assessed follicle count/diameter (days 11, 13), ovulation (day 13), corpus luteum (CL) number/characteristics (day 20), and pregnancy (day 44). Serum progesterone was measured on day 20; Group T underwent clinical/hematological evaluations (days 0, 20, and 44). Estrus signs were more frequent (P < 0.01) in T (100%) than NC (50%), while PC (85%) did not differ. Ovulation rates were similar between T (93%) and PC (95%), but higher than NC (50%; P < 0.05). On day 13, largest follicle diameter did not differ (P > 0.05) among groups; however, fewer follicles > 2 mm occurred in PC than NC and T (P < 0.05). CL number was higher in T than PC (2.0 ± 0.3 vs. 1.0 ± 0.0, P < 0.01), while NC did not differ (1.0 ± 0.25). Conversely, pregnancy rate was higher (P < 0.05) in PC (70%) than T (28.6%) and NC (20%). Among ovulated ewes, progesterone concentration and progesterone/CL ratio did not differ among groups (P = 0.92 and P = 0.08, respectively). No relevant r-eCG-related clinical or hematological alterations occurred. In conclusion, 400IU r-eCG effectively induces estrus and ovulation without adverse effects; however, the discrepancy between ovulatory response and pregnancy rate underscores the need for further study refinement to improve fertility.
BACKGROUND: The electrocardiogram (ECG) is widely used to infer infarct location and extent in anterior myocardial infarction (MI), based on either anatomical lead proximity or vectorial orientation of ST-segment deviation. However, the validity of these approaches against direct imaging of myocardial injury remains uncertain. METHODS: In this prospective study, 105 patients with anterior MI underwent cardiac magnetic resonance (CMR) imaging 3-7 days after presentation. Admission ECGs were analyzed using (1) conventional ECG localization categories, and (2) simplified frontal and horizontal ST-axis orientation. CMR-defined injury distribution was assessed using late gadolinium enhancement and myocardial edema imaging. RESULTS: Conventional ECG localization categories demonstrated no significant association with CMR-defined infarct distribution (P = 0.24), with poor agreement (κ = 0.122) and substantial overlap across categories. Simplified ST-axis orientation showed modest and inconsistent associations with infarct location and did not meaningfully explain infarct size. In contrast, global ST-segment burden was associated with CMR-defined infarct size (ΣSTE: standardized β = 0.307, P = 0.002; lead count: standardized β = 0.267, P = 0.007). CONCLUSIONS: In this selected cohort of reperfused LAD-related anterior STEMI patients undergoing early CMR, conventional ECG localization categories and simplified ST-axis orientation showed poor or inconsistent correspondence with CMR-defined infarct distribution, whereas global ST-segment burden showed a modest association with infarct size. These findings suggest that, in this cohort, the ECG may be better suited to reflect the extent of myocardial injury rather than its precise anatomical location.
In order to confirm or refute the previously held view that electrocardiographic (ECG) abnormalities are frequent in diabetic ketoacidosis, we have undertaken continuous ECG monitoring for 24 h, with subsequent computer analysis, in 14 diabetic patients admitted with severe ketoacidosis. There was a steady fall in heart rate during the 24-h except in 3 severely dehydrated patients. Depression of the ST-segment was minimal and ST-segment height correlated significantly with heart rate, whereas no consistent relationship was found between T-wave amplitude and either heart rate or plasma potassium. Two patients developed short periods of supraventricular ectopic beats. Although ECG monitoring has been claimed to be a useful aid in the management of diabetic ketoacidosis, this study clearly demonstrates that significant ECG changes are rare and ECG monitoring thereafter adds little to careful clinical observation and regular biochemical assessment.
Objective.Chagas disease, a neglected tropical disease (NTD) with significant cardiovascular impact, remains underdiagnosed in resource-limited regions. Electrocardiogram (ECG) screening offers a low-cost tool for detecting cardiac involvement, yet algorithm development is challenged by label noise, data scarcity, and the latent nature of infection. This study proposes a robust ECG-based screening framework that explicitly addresses these constraints.Approach.We introduce aReliability-Aware Hierarchical Learningstrategy that calibrates supervision according to data provenance, prioritizing serology-confirmed labels over noisy self-reports. To mitigate data scarcity, we compare a specialized convolutional neural network (CNN) trained from scratch with a transfer learning approach based on a Spatio-Temporal ECG foundation Model (FM). Performance is evaluated across varying data scales, and the representation structure is analyzed to interpret model behavior.Main results.On the official hidden test set of the George B. Moody PhysioNet/Computing in Cardiology Challenge 2025, our approach achieved a Challenge Score of 0.163. We observe that while the specialized CNN performs competitively in data-rich regimes, the FM exhibits superior robustness in extreme low-resource settings. Furthermore, performance reaches a plateau imposed by underlying disease physiology. Bimodal score distributions suggest that models distinguish established cardiomyopathy from indeterminate infection, which remains electrophysiologically indistinguishable from healthy controls.Significance.These findings clarify both the potential and intrinsic limits of ECG-based AI screening for NTD-associated cardiac involvement. Reliability-aware supervision and data-efficient transfer learning provide a practical framework toward scalable and clinically meaningful ECG screening systems in resource-constrained environments.
Twentyfour male patients with sustained myocardial infarction (MI) were studied with 12-lead ECG and systolic time intervals (STI) 5 months after the acute episode. From the ECGs were calculated the summed voltages of the R wave (sigma R), the Q wave (sigma Q), and the ST segment deviation (sigma ST). These ischaemic ECG variables were correlated with the STI parameters of left ventricular function: LVETI, PEP and PEP/LVET. Statistically significant regression equations relating the ECG changes to the STI variables were found in anterior MI, for sigma ST in the entire series, but not in inferior MI. Thus a simple and rapid inspection of the resting 12-lead ECG gives an indirect but reliable quantitative estimate of left ventricular function in patients with a sustained myocardial infarction.
A comparison of electrocardiographic and anatomic data was made in 74 patients with acute myocardial infarction with the purpose of investigating QRS-complex changes in macrofocal myocardial infarction, and establishing the correlation between ECG data and the volume of the infarcted myocardium. It has been shown that subendocardial and transmural necrosis of the anterior wall of the left ventricle was in all cases reflected on ECG by QS, while transmural necrosis of the posterior wall was associated in 86% of the cases with the presence of QR, Qr or qR on ECG. Thus, the estimation of myocardial necrosis depth by ECG data is difficult. An increase in myocardial necrosis area is paralleled by an increase in Q wave duration, in Q/R ratio value, and by a decrease in R wave amplitude. There was no significant linear correlation between the volume of necrosis area and the amplitude of Q wave of the number of ECG leads in which signs of myocardial infarction were detected.
Within the scope of an epidemiologic study on risk factors and coronary heart diseases, 1726 mentally ill, aged 40-69, under permanent hospitalization were examined electrocardiographically. There were few pronounced indications of a relationship between pathological ECG findings and psychopharmaca. ECG changes were rarest among patients treated exclusively with non-tricyclic drugs, and most often among those patients who received tricyclics and non-tricyclics simultaneously. Statistically ascertained, however, was only the connection with lesser pathological changes in the rest and load ECG's (T-flattening). In this connection, these disturbances appeared more often among women. A reciprocal effect between sex and the influence of psychopharmaca appeared on the ECG. Contrary to males, females under treatment with tricyclica or with several psychopharmaca simultaneously showed more ECG changes than those treated without medication.
BACKGROUND: Modern pacemakers incorporate arrhythmia-response algorithms, ventricular pacing minimization protocols, and safety mechanisms that generate ECG patterns indistinguishable from pathological AV block, sensing malfunction, or device-mediated tachycardia. Failure to recognize these algorithm-driven signatures leads to unnecessary interventions, misdiagnosis, and inappropriate device reprogramming. This manuscript is the second in a two-part series on pacemaker ECG interpretation. METHODS: We conducted a narrative review of peer-reviewed literature and device-specific documentation on algorithm-driven ECG behavior, synthesizing evidence across arrhythmia recognition, upper rate physiology, ventricular pacing minimization, mode switching, safety mechanisms, and hysteresis algorithms. RESULTS: Pacemaker-mediated tachycardia produces regular paced wide-complex tachycardia locked at the upper tracking rate, initiated by any event with retrograde VA conduction. Ventricular tachycardia is identified by QRS morphology diverging from the known paced pattern, absent pacing spikes, and AV dissociation. Upper rate Wenckebach behavior mimics Mobitz type I AV block; 2:1 upper rate response mimics second-degree AV block. Ventricular pacing minimization algorithms produce isolated nonconducted P waves and prolonged AV intervals that simulate pathological conduction disease. Mode switching causes abrupt rate drops misidentified as output failure. Ventricular safety pacing generates a conspicuously short, fixed AV interval. Three discrete pacing artifacts reflect AV-sequential cardiac resynchronization therapy (CRT), ventricular safety pacing in CRT, or His-bundle pacing with backup RV output. Rate and AV hysteresis produce pauses and wandering AV intervals mimicking oversensing or Wenckebach periodicity. CONCLUSIONS: Recognizing algorithm-driven ECG patterns requires knowledge of device timing intervals and refractory periods, which lets clinicians distinguish programmed behavior from true malfunction or cardiac arrhythmia.
To assess the prevalence of possible, latent coronary heart disease (CHD) among physically active men, 149 elite cross-country skiers in three age groups (26-33, 43-50 and 58-64 years) were invited for an examination which included clinical examination, Vitalogram, resting ECG, and a near maximal bicycle test. Of the invited men, 122 participated, i.e. 81.8%. The following findings were made: Normal clinical findings in all except 2, low resting heart rate, lung function parameters of about normal mean; voltage signs of left ventricular hypertrophy in resting ECG in 61/122, incomplete right bundle branch block in 14/122, codable Q waves (Minnesota Code, MC) in 5/87 from the highest age groups, ischaemic exercise ECG changes of MC 4.1 or 4.2 types in 11/87 vs. 1/35 in the two oldest vs. the youngest age group. Physical performance was very high in all age groups, but regular training did not seem to inhibit the normal age-dependent decline in physical performance. The resting and exercise ECG data in the two oldest age groups did not differ favourably from similar data obtained in sedentary men of the same age from approximately the same geophraphic area. Thus, it is possible that regular strenuous exercise and training may not protect against the development of CHD. The implications of such a view are briefly discussed.
Although many ECG criteria exist for diagnosis of left ventricular hypertrophy (LVH) in hypertensive man, little is known of which specific ECG changes accompany progression of LVH with duration of hypertension. The spontaneously hypertensive rat (SHR) provides the best animal model thus far developed for studying this process since these animals demonstrate a progressive increase in left ventricular/body weight ratio with age. Electrocardiograms were performed under light ether anesthesia in four age groups of SHR and two normotensive Wistar strains (NR and WKY). Analysis of variance for two factors (rat strain and age) revealed progressively increased QRS and P-wave duration and delay in intrinsicoid deflection in SHR (p less than 0.001). Bipeak P-wave notching was also noted in SHR similar to left atrial abnormality in hypertensive man. Thus, specific ECG indices can be identified in association with the known progressive increase in left ventricular mass in SHR and should provide a better means to understand evolving ECG changes in LVH.
Great ECG changes (Frank system) with age were found in normal men. ECG diagnostic criteria valid in Romania were studied by multivariate analyses in men aged 40--60 suffering from hypertension (Hyp) without cardiac congestive failure (CCF), out of which one group with left ventricular hypertrophy (LVH) and another one without it. Echocardiographic studies in normal and hypertensive men past forty, as well as studies in experimental Hyp with LVH and without CCF were carried out. Heart X-ray evaluation is not a functional one. Some non-invasive methods in men do not determine an accurate evaluation of LV performance. The increase of LV muscular mass alone cannot explain the ECG changes in LVH in Hyp without CCF. Two conditional adaptive mechanisms: the liberation of catecholamines from the myocardium storage, induced by the pressure overload stress, and the increase of intracellular Ca++ influx could contribute to the respective ECG changes.