Electrocardiographic (ECG) analysis becomes challenging in the presence of concurrent ventricular preexcitation (WPW) and right bundle branch block (RBBB) due to their mutually interfering ECG manifestations. Interpolate...Electrocardiographic (ECG) analysis becomes challenging in the presence of concurrent ventricular preexcitation (WPW) and right bundle branch block (RBBB) due to their mutually interfering ECG manifestations. Interpolated ventricular premature contractions (IPVCs) can transiently alter the conduction velocity and refractory period of the WPW accessory pathway and the His-Purkinje system, thereby leading to intermittent manifestation of WPW or RBBB. In Case 1 and Case 2, IPVCs converted sinus beats from the WPW + RBBB pattern to the pure RBBB pattern; in Case 3, sinus beats after IPVCs changed from the pure WPW pattern to the WPW + RBBB pattern. Full utilization of such valuable dynamically emerging information, together with a thorough and systematic examination of the ECG including the dissection of the initial, middle, and terminal electrical forces of the QRS complex, is crucial for an accurate diagnosis.
BACKGROUND: Left bundle branch area pacing (LBBAP) is increasingly used to achieve physiologic ventricular activation. However, electrical "success" may differ by baseline substrate: resynchronization in left bundle bran...BACKGROUND: Left bundle branch area pacing (LBBAP) is increasingly used to achieve physiologic ventricular activation. However, electrical "success" may differ by baseline substrate: resynchronization in left bundle branch block (LBBB) versus preservation of synchrony in intrinsically narrow QRS. Ultra-high-frequency ECG (UHF-ECG) provides quantitative indices of ventricular activation timing and dispersion beyond QRS duration. METHODS: We report a contrastive two-case series undergoing dual-chamber pacing with an LBBAP lead. Pre- and post-implant UHF-ECG was analyzed using ventricular depolarization maps and dyssynchrony indices, including ventricular electrical delay (VED) and mean ventricular dispersion (MeanVD). Conventional ECG timing metrics were assessed in parallel (QRS duration when available, R-wave peak time [RWPT], and inter-peak intervals). Global RWPT was calculated as the sum of RWPT in lead I and lateral precordial lead (V5/6 or V6, depending on availability). RESULTS: In Case 1 (baseline complete LBBB), LBBAP resulted in a resynchronization phenotype with QRS duration reduction from 201.6 ms to 137.6 ms, VED16 improvement from +48 ms to -5 ms, and MeanVD16 reduction from 85 ms to 66 ms. RWPT(V5/6) was 90.0 ms and RWPT(I) 96.8 ms, yielding a global RWPT of 186.8 ms. In Case 2 (baseline narrow QRS), UHF-ECG demonstrated preservation of synchrony with stable VED18 (-3 ms pre- and post-implant) and low MeanVD18 (25 ms to 24 ms), alongside RWPT(V6) 87.6 ms and RWPT(I) 56.0 ms (global RWPT 143.6 ms). CONCLUSIONS: UHF-ECG provided reproducible, quantitative descriptions in both cases and was demonstrative of two clinically relevant response patterns after LBBAP (resynchronization in baseline LBBB and preservation of low dyssynchrony in baseline narrow QRS). These findings are descriptive and warrant confirmation in larger cohorts.
We report a 52-year-old man with coronary artery disease, reduced left ventricular ejection fraction, and a cardiac resynchronization therapy-defibrillator (CRT-D), admitted to the emergency department for palpitations....We report a 52-year-old man with coronary artery disease, reduced left ventricular ejection fraction, and a cardiac resynchronization therapy-defibrillator (CRT-D), admitted to the emergency department for palpitations. Surface ECG showed a wide-complex tachycardia with a 2:1 ventricular-to-atrial (V:A) relationship. Device interrogation revealed episodes detected in the ventricular tachycardia monitor zone, according to the atrioventricular discrimination algorithms. Detailed analysis of surface ECG and device intracardiac electrograms was performed, followed by an electrophysiological study and catheter ablation of the responsible circuit of the tachycardia. This case illustrates the diagnostic complexity and differential diagnosis of tachycardias presenting with a 2:1 V:A relationship and highlights the importance of integrating surface ECG, device tracings, and electrophysiological findings to correctly identify the underlying mechanism, to avoid misclassification by device algorithms, and to treat the arrhythmia effectively.
BACKGROUND: Atrial septal defects (ASD) are often asymptomatic during childhood, resulting in a delayed diagnosis. Electrocardiography (ECG) screening is known to have a limited ability to detect ASD, relying mainly on Q...BACKGROUND: Atrial septal defects (ASD) are often asymptomatic during childhood, resulting in a delayed diagnosis. Electrocardiography (ECG) screening is known to have a limited ability to detect ASD, relying mainly on QRS abnormalities, such as incomplete right bundle branch block (IRBBB). In contrast, P waves have been underused because they are small, often on a trended baseline, and thus difficult to quantify accurately. This observational study examined the utility of baseline-corrected P-wave amplitude in the identification of ASD. METHODS: We analyzed digital ECG data from 45 secundum ASD patients 4-9 years old and 94 matched controls without structural heart defects. Using a semi-automated algorithm, we precisely measured the P-wave amplitude following rigorous baseline correction. We conducted a receiver operating characteristic (ROC) curve analysis to differentiate ASD patients from controls. RESULTS: The overall performance of the P-wave amplitude in lead V3 was high, with an area under the ROC curve (AUROC) of 0.883. When the analysis was limited to patients with defect sizes of ≥5 mm, the V3 amplitude had an excellent AUROC (0.954) with 83.3% sensitivity and 95.7% specificity, outperforming conventional ECG findings, including IRBBB. This significance was supported by a good correlation between the V3 amplitude and the right atrial size quantified by echocardiography. CONCLUSIONS: The present study demonstrates the potential utility of accurately measured P-wave amplitude for the detection of hemodynamically significant pediatric ASD. Further investigations, including external validation in diverse clinical settings and the development of a fully automated analytic algorithm, are required before clinical implementation.
BACKGROUND: Cardiac amyloidosis (CA) is an infiltrative cardiomyopathy that can lead to various arrhythmias. Electrocardiogram (ECG) abnormalities have been reported in CA, though there is limited data on the prognostic...BACKGROUND: Cardiac amyloidosis (CA) is an infiltrative cardiomyopathy that can lead to various arrhythmias. Electrocardiogram (ECG) abnormalities have been reported in CA, though there is limited data on the prognostic significance of these findings. METHODS: Between 1/1997 and 12/2019, we identified high arrhythmic-risk patients with CA who had clinically been treated with an implantable cardioverter defibrillator (ICD) to prevent sudden cardiac death from our multi-center practice. We studied baseline characteristics, comorbidities, echocardiograms, and ECG parameters. Regression models were used to evaluate the association of ECG characteristics with mortality or ICD shock while adjusting for baseline confounders. RESULTS: We identified 44 patients with CA who had ICD implantation for prevention of sudden cardiac death. Baseline characteristics included 9 (20.5%) females, 19 (43.0%) with AL CA, and 4 (9.1%) who were non-white. The mean age was 65 ± 11 years in those with AL CA and 71 ± 10 years in those with transthyretin CA. Indications for ICD implantation include syncope in 3 (7.0%) patients, ventricular arrhythmias in 16 (37.2%) patients, and both syncope and ventricular arrhythmias in 2 (4.7%) patients. Overall, ICD implantation was performed for primary prevention in 26 (59.1%) patients and for secondary prevention in 18 (40.9%) patients. Low voltage QRS was noted in 8 (42.1%) of AL CA cohort (p = 0.07) and 6 (25%) of ATTR CA cohort had LBBB (p = 0.08). Bradycardia was more prevalent in ATTR CA than in AL CA. In unadjusted analysis, only age and reduced ejection fraction were associated with death or ICD shock. There were no ECG parameters associated with death or ICD shock. CONCLUSIONS: In a high arrhythmic risk cohort of CA patients with ICDs, no specific ECG parameter was associated with increased all-cause mortality or ICD shock.
A 74-year-old female patient presented with atrial premature beat (APB) bigeminy. Sinus beats were conducted via the fast pathway (FP), while APBs were conducted via the slow pathway (SP). Two types of QRS complexes with...A 74-year-old female patient presented with atrial premature beat (APB) bigeminy. Sinus beats were conducted via the fast pathway (FP), while APBs were conducted via the slow pathway (SP). Two types of QRS complexes with different natures appeared alternately, yet the RR intervals remained regular, mimicking accelerated junctional rhythm complicated with interfering atrioventricular dissociation. This article explores the pathogenesis of this rare electrocardiographic phenomenon.
BACKGROUND: Takotsubo syndrome (TTS) is an acute reversible myocardial injury with typical electrocardiographic (ECG) features, which is often obscured by right ventricular pacing (RVP) and causes diagnostic challenges....BACKGROUND: Takotsubo syndrome (TTS) is an acute reversible myocardial injury with typical electrocardiographic (ECG) features, which is often obscured by right ventricular pacing (RVP) and causes diagnostic challenges. Accurate ECG interpretation in paced patients is critical to avoid mismanagement. OBJECTIVE: To systematically summarize the ECG features of TTS in patients with RVP and clarify how these features aid in differentiating TTS from acute coronary syndrome (ACS). METHODS: We conducted a PRISMA-compliant systematic review (PROSPERO: CRD420251145162) searching PubMed, Embase, and Web of Science (1990-July 2025). RESULTS: Of 53 screened studies, 15 cases (14 publications, 2006-2025) were included. Patients were 86.7% female (mean age 71 years). Key ECG findings: All evaluable cases lacked ST-segment depression or abnormal Q waves; 8 had ST-segment elevation (predominantly in precordial leads V2-V5), 10 had concordant T-wave inversion, 12 had corrected QT interval prolongation, 4 showed QRS amplitude attenuation (all post-pacemaker TTS [PP-TTS]), and 2 experienced ventricular tachycardia. Subgroup analysis revealed that T-wave inversion was more frequent in patients with a pacemaker history (pH-TTS, 100%) than in PP-TTS (44.4%), with statistical significance (P = 0.012). CONCLUSIONS: TTS with RVP exhibits distinct ECG features (e.g., concordant T-wave inversion, no ST-segment depression/abnormal Q waves) that distinguish it from ACS. Clinicians should use these features to diagnose TTS in paced patients, avoiding unnecessary invasive procedures.
INTRODUCTION: Handheld mobile ECG (mECG) devices offer potential for remote QTc surveillance in congenital long QT syndrome (cLQTS), but validation against standard 12‑lead ECGs is limited. METHODS AND RESULTS: We studie...INTRODUCTION: Handheld mobile ECG (mECG) devices offer potential for remote QTc surveillance in congenital long QT syndrome (cLQTS), but validation against standard 12‑lead ECGs is limited. METHODS AND RESULTS: We studied 102 cLQTS patients (median age 36), using consecutive 12‑lead ECGs and KardiaMobile 1 L and 6 L recordings. Agreement with 12‑lead ECGs was assessed using Lin's concordance correlation coefficient (CCC) and Bland-Altman analysis. Mean biases were < 10 ms, within the predefined threshold for excellent agreement. Reproducibility was high. CONCLUSION: These findings support the cautious integration of mECG-based QTc monitoring for high-risk cLQTS patients.
The presence of a large ostium secundum atrial septal defect (OS-ASD) results in right atrial and right ventricular volume overload followed by pulmonary hypertension. In this context, a Crochetage electrocardiographic p...The presence of a large ostium secundum atrial septal defect (OS-ASD) results in right atrial and right ventricular volume overload followed by pulmonary hypertension. In this context, a Crochetage electrocardiographic pattern can be observed in some cases, indicating a particular clinical and cardiological evolution. We present a case of an 8-year-old boy with OS-ASD and pulmonary hypertension, whose electro-vectorcardiogram reveal the typical characteristics first described in 1958.
BACKGROUND: Septic shock remains a leading cause of mortality in critically ill patients. Electrocardiography (ECG) is a rapid, non-invasive tool, and the T-wave to R-wave amplitude ratio (T/R ratio) has been proposed as...BACKGROUND: Septic shock remains a leading cause of mortality in critically ill patients. Electrocardiography (ECG) is a rapid, non-invasive tool, and the T-wave to R-wave amplitude ratio (T/R ratio) has been proposed as a marker of electrolyte disturbances and myocardial stress. Its prognostic value in septic shock, however, is unclear. OBJECTIVE: To evaluate the association between the admission T/R ratio and short-term mortality in patients with septic shock and to identify independent predictors of mortality. METHODS: We conducted a single-center, retrospective observational study of 319 adult patients diagnosed with septic shock who had a 12‑lead ECG on admission. T and R wave amplitudes were manually measured in leads II and V5, and the T/R ratio was calculated. Demographic, clinical, and laboratory data were collected. Multivariable logistic regression was used to identify independent predictors of in-hospital mortality. RESULTS: Among 319 patients, 214 (67.1%) experienced in-hospital mortality. The T/R ratio was not significantly associated with mortality in univariable or multivariable analyses. Independent predictors of mortality included advanced age (OR, 1.04; 95% CI, 1.01-1.07), elevated white blood cell count (OR, 1.06; 95% CI, 1.00-1.11), hypoalbuminemia (OR, 0.89; 95% CI, 0.84-0.94), hyperkalemia (OR, 1.53; 95% CI, 1.01-2.31), abnormal T wave axis (OR, 1.01; 95% CI, 1.00-1.01), and heart failure (OR, 3.92; 95% CI, 1.35-10.85). The regression model demonstrated good predictive performance (accuracy 75.9%, sensitivity 88.9%, specifically 44.3%, AUC 0.816). CONCLUSION: The T/R ratio on admission ECG does not reliably predict short-term mortality in patients with septic shock. Mortality is primarily driven by established clinical and laboratory predictors. ECG-derived indices may provide complementary information but should be interpreted alongside clinical scoring systems and biochemical markers to improve risk stratification and guide management in this high-risk population.
Chronic heart failure (CHF) is a condition affecting millions worldwide, characterized by the heart's reduced ability to pump blood efficiently. Conventional diagnostics, such as imaging and ECG assessments, can be time-...Chronic heart failure (CHF) is a condition affecting millions worldwide, characterized by the heart's reduced ability to pump blood efficiently. Conventional diagnostics, such as imaging and ECG assessments, can be time-consuming and expensive, often identifying CHF only after significant progression. Early detection is crucial for improving treatment options and reducing healthcare costs. Heart rate variability (HRV), which measures the variation in time intervals between heartbeats, is emerging as a non-invasive and cost-effective biomarker for CHF detection. HRV reflects the autonomic nervous system's regulatory functions, often impaired in CHF patients. This study aims to assess advanced HRV measures for earlier CHF detection. The research involved examining CHF patients (N = 934, Age 65 ± 12) compared to healthy controls (N = 274, Age 43 ± 17). Data was sourced from Physionet and the Telemetric and Holter ECG Warehouse, with RR interval (RRI) data extracted from 24-h Holter recordings. The study utilized dynamical detrended fluctuation analysis (DDFA), which considers changes in RRI correlations over time and scale, resulting in scaling exponent α(t,s). This was further aggregated into scale and heart rate (HR)-dependent forms, α(HR,s), classified using XGBoost ensemble method with 10-fold nested cross-validation. The classifier achieved 97% sensitivity and 90% specificity for distinguishing between CHF and control groups. Sensitivity and specificity remained consistent across subgroup analyses based on beta blocker medication and NYHA class. This method demonstrated high classification accuracy, suggesting potential utility for early CHF detection, independent of CHF severity.
Herein, we report a rare clinical case of competitive ventricular pacing caused by the accidental reactivation of a retained pacemaker two years after device replacement. Initially, two years following the implantation o...Herein, we report a rare clinical case of competitive ventricular pacing caused by the accidental reactivation of a retained pacemaker two years after device replacement. Initially, two years following the implantation of the new pacemaker, the device demonstrated typical dual-chamber pacing. However, recent follow-up electrocardiography revealed two distinct QRS morphologies. Holter monitoring, imaging studies, and a review of prior procedural records confirmed that this phenomenon was caused by the unexpected reactivation of the retained pacemaker, leading to competitive ventricular pacing. A detailed analysis of the underlying causes of inadvertent reactivation led to the implementation of targeted interventions, which successfully resolved the issue of competitive ventricular pacing induced by dual pacemakers.
A 40-year-old male presented with recurrent episodes of documented narrow complex tachycardia (NCT). Baseline electrocardiogram (ECG) did not reveal any manifest preexcitation. During an electrophysiological (EP) study,...A 40-year-old male presented with recurrent episodes of documented narrow complex tachycardia (NCT). Baseline electrocardiogram (ECG) did not reveal any manifest preexcitation. During an electrophysiological (EP) study, he was noted to have spontaneous induction of narrow complex tachycardia during catheter manipulation. The ECG tracings from the EP system showed a spontaneous transition to right bundle branch block in the ongoing tachycardia. What is the likely mechanism of the tachycardia? Clinical trial registration: Not applicable.
BACKGROUND: Accurate ECG interpretation is an essential skill required for medical school graduation. Multiple choice question (MCQ) tests are widely used to assess student competence due to the feasibility of administra...BACKGROUND: Accurate ECG interpretation is an essential skill required for medical school graduation. Multiple choice question (MCQ) tests are widely used to assess student competence due to the feasibility of administration; however, many existing MCQs ECG tests lack strong validity evidence. Our study aimed to develop validity evidence for an MCQ based ECG assessment using Kane's validity framework. METHODS: We analyzed the internal structure of a 22-item MCQ test. A modified Hofstee and Angoff method were used to set the passing standard. We compared MCQ scores with results from open-ended ECG quizzes to examine the relationship to a more "real-world" assessment. Pearson correlation coefficient and linear regression assessed the strength of the association between the two assessments and Welch's t-test compared open-ended scores between high and low MCQ performers. FINDINGS: Eighteen of the 22 items met performance criteria. A passing score of 11/18 was set to reflect the desired failure rate of 0-10%. The Pearson correlation coefficient between MCQ and open-ended ECG scores was 0.414, indicating a moderate positive linear relationship. Linear regression showed an R of 0.19 between the two assessments. Students scoring in the lowest MCQ quartile had significantly lower open-ended scores (p < 0.001). CONCLUSION: These findings provide validity evidence for an MCQ assessment that identifies students below a minimum competency threshold. While the test effectively identifies struggling learners, it lacks the sensitivity to differentiate proficiency levels above that threshold. Future work should explore efficient methods for assessing and providing feedback on open-ended ECG interpretation.
This article reports a case of a 34-year-old male patient with ventricular pre-excitation (WPW). Under sinus rhythm, the patient presented with alternating fully manifest WPW complexes and normal cardiac beats. In additi...This article reports a case of a 34-year-old male patient with ventricular pre-excitation (WPW). Under sinus rhythm, the patient presented with alternating fully manifest WPW complexes and normal cardiac beats. In addition, premature beats unrelated to P waves were observed, with morphology consistent with the fully manifest WPW complexes. Such premature beats are highly susceptible to misdiagnosis as accelerated idioventricular rhythm or accelerated junctional rhythm with left bundle branch block (LBBB).
OBJECTIVE: Fever is a common cause of emergency department admission and may induce transient alterations in cardiac electrophysiology. P-wave dispersion (PWD), a noninvasive marker of atrial conduction heterogeneity, is...OBJECTIVE: Fever is a common cause of emergency department admission and may induce transient alterations in cardiac electrophysiology. P-wave dispersion (PWD), a noninvasive marker of atrial conduction heterogeneity, is associated with an increased risk of supraventricular arrhythmias, particularly atrial fibrillation. To evaluate the effect of acute fever on P-wave dispersion and related atrial conduction parameters in patients without known structural heart disease, using a within-subject comparison between febrile and afebrile states. MATERIALS AND METHODS: This single-center, prospective observational study was conducted in the emergency department of a tertiary care hospital between December 2024 and April 2025. Adult patients (≥18 years) with a body temperature > 37.9 °C were included. Twelve‑lead electrocardiograms were obtained during the febrile period at presentation and after defervescence. Maximum P-wave duration (Pmax), minimum P-wave duration (Pmin), and P-wave dispersion (PWD) were calculated. RESULTS: A total of 216 patients were enrolled. Median body temperature decreased from 38.3 (38-39) °C before treatment to 36.9 (36.6-37.1) °C after treatment (p < 0.001). During fever, Pmax, Pmin, and PWD values were significantly higher than those measured after defervescence (Pmax: 89 vs. 80 ms; Pmin: 40 vs. 40 ms; PWD: 48 vs. 40 ms; p < 0.001). A weak positive correlation was observed between changes in body temperature and Pmax (ρ = 0.135; p = 0.048), with no significant association for Pmin or PWD. CONCLUSION: Acute fever was associated with transient alterations in P-wave dispersion and atrial conduction parameters. These changes appeared to be reversible following fever resolution. The potential clinical and arrhythmic implications of these findings remain to be clarified and warrant further investigation.
We report a 69-year-old woman with persistent palpitation, a history of myocardial infarction. ECG showed irregular wide QRS tachycardia with positive precordial concordance and flutter waves, initially misdiagnosed as a...We report a 69-year-old woman with persistent palpitation, a history of myocardial infarction. ECG showed irregular wide QRS tachycardia with positive precordial concordance and flutter waves, initially misdiagnosed as atrial flutter with accessory pathway. Direct current cardioversion restored sinus rhythm but failed to terminate tachycardia, revealing ventricular tachycardia (VT). Amiodarone resolved VT. This case highlights the challenge of differentiating wide QRS tachycardias, emphasizing QRS morphology and atrioventricular (AV) relationship analysis for accurate diagnosis.
Bejarano-Arosemena R, Pérez-David E, Lacalzada-Almeida J
… +15 more, García-Martín A, Bonet Basiero A, Sáenz-Molina M, Ruiz-Ortiz M, González-Mansilla A, Garrido Morro I, Tobar J, Díez-Villanueva P, Dalmau R, Esteban Sastre MJ, Alfonso F, Valbuena S, Bruña V, Bermejo J, Martínez-Sellés M
BACKGROUND: Advanced interatrial block (IAB) is found in about 10% of subjects ≥75 years and is associated with atrial fibrillation and stroke. It is unclear if IAB association with cardiovascular events is a casual or n...BACKGROUND: Advanced interatrial block (IAB) is found in about 10% of subjects ≥75 years and is associated with atrial fibrillation and stroke. It is unclear if IAB association with cardiovascular events is a casual or non-causal association. OBJECTIVES: To determine the association of advanced IAB with left atrial (LA) imaging parameters and cerebral microemboli. METHODS: Prospective multicenter study that included 190 subjects ≥75 years without significant structural heart disease, including 83 patients with advanced IAB and 107 controls with normal P-wave (matched by age and cardiovascular risk factors). Electrocardiogram and transthoracic echocardiography were performed in all subjects. Cardiac and brain magnetic resonance imaging (MRI) were done in a exploratory subgroup of 23 and 26 subjects, respectively. RESULTS: Mean age was 80.9 years old (81.5 in advanced IAB vs. 80.5 in controls, p = 0.14) and 48.9% were females. There were no significant differences between patients with advanced IAB and controls in LA imaging parameters: reservoir strain (22.5 vs. 22.8%, p = 0.88), conduit strain (-12.6 vs. -11.4%, p = 0.41), contraction strain (-13.1 vs. -14.1%, p = 0.59), maximal 3D volume index (29.2 vs. 30.8 ml/m, p = 0.48), ejection fraction (45.7 vs. 43.6%, p = 0.50), fibrosis burden assessed by Late Gadolinium Enhancement (7.4 vs. 8.8% of myocardium, p = 0.67). In a small brain MRI subgroup, patients with advanced IAB showed a numerically higher prevalence of silent brain lesions than controls; however, this difference was not statistically significant (p = 0.25). CONCLUSIONS: When compared to controls with normal P wave, matched by age and cardiovascular risk factors, advanced IAB is not associated with abnormal LA imaging parameters. Within the limitations of this underpowered study, advanced IAB may have a non-causal association with clinical events, although a causal relationship cannot be excluded.
BACKGROUND: The standard 12‑lead electrocardiogram (ECG) represents cardiac electrical activity through two-dimensional projections, requiring clinicians to mentally reconstruct the three-dimensional behavior of the card...BACKGROUND: The standard 12‑lead electrocardiogram (ECG) represents cardiac electrical activity through two-dimensional projections, requiring clinicians to mentally reconstruct the three-dimensional behavior of the cardiac vector. This process is highly dependent on experience and may limit interpretation accuracy. OBJECTIVE: To introduce and demonstrate a novel qualitative method for three-dimensional (3D) ECG visualization based on orthogonal leads, designed to enhance spatial and temporal interpretation of cardiac electrical activity. METHODS: Orthogonal X, Y, and Z leads from the Frank system were analyzed using a circular polar representation that enables simultaneous visualization of vector magnitude and direction over time. Representative recordings from normal subjects and patients with conduction disturbances, myocardial infarction, and pre-excitation were evaluated. RESULTS: The proposed 3D ECG representation provided intuitive visualization of cardiac electrical activity across frontal, transverse, and sagittal planes. The method enabled clear identification of wave onset and offset, spatial orientation of depolarization and repolarization vectors, and characteristic patterns associated with ischemia, bundle branch block, and accessory pathway conduction. These findings are presented as qualitative, demonstrative results supported by reproducible clinical examples. CONCLUSION: Three-dimensional ECG visualization using orthogonal leads offers a practical and informative complement to the standard ECG, facilitating improved qualitative interpretation and supporting future integration with automated and artificial intelligence-based analysis systems.