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Electrocardiographic Imaging of Repolarization Abnormalities.

ABSTRACT: Background Dispersion and gradients in repolarization have been associated with life-threatening arrhythmias, but are difficult to quantify precisely from surface electrocardiography. The objective of this study was to evaluate electrocardiographic imaging (ECGI) to noninvasively detect repolarization-based abnormalities. Methods and Results Ex vivo data were obtained from Langendorff-perfused pig hearts (n=8) and a human donor heart. Unipolar electrograms were recorded simultaneously during sinus rhythm from an epicardial sock and the torso-shaped tank within which the heart was suspended. Regional repolarization heterogeneities were introduced through perfusion of dofetilide and pinacidil into separate perfusion beds. In vivo data included torso and epicardial potentials recorded simultaneously in anesthetized, closed-chest pigs (n=5), during sinus rhythm, and ventricular pacing. For both data sets, ECGI accurately reconstructed T-wave electrogram morphologies when compared with those recorded by the sock (ex vivo: correlation coefficient, 0.85 [0.52-0.96], in vivo: correlation coefficient, 0.86 [0.52-0.96]) and repolarization time maps (ex-vivo: correlation coefficient, 0.73 [0.63-0.83], in vivo: correlation coefficient, 0.76 [0.67-0.82]). ECGI-reconstructed repolarization time distributions were strongly correlated to those measured by the sock (both data sets, R² ≥0.92). Although the position of the gradient was slightly shifted by 8.3 (0-13.9) mm, the mean, max, and SD between ECGI and recorded gradient values were highly correlated (R²=0.87, 0.75, and 0.86 respectively). There was no significant difference in ECGI accuracy between ex vivo and in vivo data. Conclusions ECGI reliably and accurately maps potentially critical repolarization abnormalities. This noninvasive approach allows imaging and quantifying individual parameters of abnormal repolarization-based substrates in patients with arrhythmogenesis, to improve diagnosis and risk stratification.

SUBMITTER: Bear LR

PROVIDER: S-EPMC8200734 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:Background Early repolarization pattern (ERP) is considered a common training-related and benign ECG finding in young adult athletes. Few data exist on ERP in the pediatric athletes population. Therefore, we aimed to evaluate the ERP prevalence, characteristics, and prognosis in pediatric athletes aged ≤16 years. Methods and Results Eight-hundred eighty-six consecutive pediatric athletes engaged in 17 different sports (mean age, 11.7±2.5 years; 7-16 years) were enrolled and prospectively evaluated with medical history, physical examination, resting and exercise ECGs, and transthoracic echocardiography during their preparticipation screening. Known cardiovascular diseases associated with sudden cardiac death was considered exclusion criteria. Athletes were followed up yearly for 4 years. The prevalence of ERP was 117 (13.2%), equally distributed in both sexes (P=0.072), irrespectively of body mass index and classification of sports. The most common ERP localizations were inferolateral and inferior leads (53.8% and 27.3%, respectively). Notching J-point morphology was the most prevalent (70%), and rapidly ascending ST elevation (96%) was the most common ST-segment morphology. Athletes with ERP were older (P<0.001) had lower rest and recovery heart rates (P<0.001), increased precordial and limb R-wave voltages (P<0.001), increased R/S Sokolow index (P<0.001), and longer PR interval (P=0.006) in comparison with the athletes without ERP. Neither major cardiovascular nor arrhythmic events, nor sudden cardiac death were recorded over a median follow-up of 4.2 years. One hundred seventeen (80.3%) athletes with ERP exhibited a persistent ERP. ERP localization and J-point morphology changed during follow-up in 11 (11.7%) and 17 (18%) of athletes, respectively. Conclusions ERP is common in pediatric athletes. It was mostly located in the inferolateral leads and associated with concave ascending ST segment with other training-related ECG changes. The lack of either sudden cardiac death or cardiomyopathies linked to sudden cardiac death over follow-up suggests that in pediatric athletes, ERP may be considered a benign training-related ECG phenomenon with a potential dynamic pattern.

Project description:BACKGROUND:Sudden cardiac death is one of the primary causes of mortality in chronic hemodialysis (HD) patients. Prolonged QTc interval is associated with increased rate of sudden cardiac death. The aim of this article is to assess the abnormalities found in electrocardiograms (ECGs), and to explore factors that can influence the QTc interval. METHODS:A total of 141 conventional HD patients were enrolled in this study. ECG tests were conducted on each patient before a single dialysis session and 15 minutes before the end of dialysis session (at peak stress). Echocardiography tests were conducted before dialysis session began. Blood samples were drawn by phlebotomy immediately before and after the dialysis session. RESULTS:Before dialysis, 93.62% of the patients were in sinus rhythm, and approximately 65% of the patients showed a prolonged QTc interval (i.e., a QTc interval above 440 ms in males and above 460ms in females). A comparison of ECG parameters before dialysis and at peak stress showed increases in heart rate (77.45±11.92 vs. 80.38±14.65 bpm, p = 0.001) and QTc interval (460.05±24.53 ms vs. 470.93±24.92 ms, p<0.001). After dividing patients into two groups according to the QTc interval, lower pre-dialysis serum concentrations of potassium (K+), calcium (Ca2+), phosphorus, calcium* phosphorus (Ca*P), and higher concentrations of plasma brain natriuretic peptide (BNP) were found in the group with prolonged QTc intervals. Patients in this group also had a larger left atrial diameter (LAD) and a thicker interventricular septum, and they tended to be older than patients in the other group. Then patients were divided into two groups according to ?QTc (?QTc = QTc peak-stress- QTc pre-HD). When analyzing the patients whose QTc intervals were longer at peak stress than before HD, we found that they had higher concentrations of Ca2+ and P5+ and lower concentrations of K+, ferritin, UA, and BNP. They were also more likely to be female. In addition, more cardiac construction abnormalities were found in this group. In multiple regression analyses, serum Ca2+ concentration before HD and LAD were independent variables of QTc interval prolongation. UA, ferritin, and interventricular septum were independent variables of ?QTc. CONCLUSION:Prolonged QT interval is very common in HD patients and is associated with several risk factors. An appropriate concentration of dialysate electrolytes should be chosen depending on patients' clinical conditions.

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Electrocardiographic Imaging of Repolarization Abnormalities.

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