Cardiac repolarization analysis using the surface electrocardiogram

2008 ◽  
Vol 367 (1887) ◽  
pp. 213-233 ◽  
Author(s):  
Esther Pueyo ◽  
Juan Pablo Martínez ◽  
Pablo Laguna
Keyword(s):  
Qt Interval ◽  
Western World ◽  
Cardiac Repolarization ◽  
T Wave ◽  
Dispersion Of Repolarization ◽  
Pathological Conditions ◽  
T Wave Alternans ◽  
Electrocardiogram Ecg ◽  
Surface Electrocardiogram ◽  
Temporal Dispersion

Sudden cardiac death (SCD) is a challenging health problem in the western world. Analysis of cardiac repolarization from the electrocardiogram (ECG) provides valuable information for stratifying patients according to their risk of suffering from arrhythmic events that could end in SCD, as well as for assessing efficacy of antiarrhythmic therapies. In this paper, we start by exploring the cellular basis of ECG repolarization waveforms under both normal and pathological conditions. We then describe basic preprocessing steps that need to be accomplished on the ECG signal before extracting repolarization indices. A comprehensive review of techniques aimed to characterize spatial or temporal repolarization dispersion is provided, together with a summary of their usefulness for clinical risk stratification. Techniques that describe spatial dispersion of repolarization are based on either differences in repolarization duration or T-wave loop morphology. Techniques that evaluate temporal dispersion of repolarization include the analysis of QT interval adaptation to heart rate changes, QT interval and T-wave variability, and T-wave alternans.

A MODIFIED CORRELATION METHOD FOR T-WAVE ALTERNANS DETECTION

2013 ◽  
Vol 25 (03) ◽  
pp. 1350030
Author(s):  
Xiangkui Wan ◽  
Kanghui Yan ◽  
Minggui Li ◽  
Dingcheng Xiang
Keyword(s):  
Heart Diseases ◽  
Correlation Method ◽  
Absolute Difference ◽  
T Wave ◽  
Formidable Challenge ◽  
Maximum Absolute Difference ◽  
T Wave Alternans ◽  
Improved Performance ◽  
The Time Domain ◽  
Electrocardiogram Ecg

Identification of individuals who are at risk for sudden cardiac death (SCD) remains a formidable challenge. T-wave alternans (TWA) evaluation is emerging as an important tool for risk stratification in patients with heart diseases. Several methods have been developed in recent years to detect and quantify TWA. One such method is known as the correlation method (CM). This method performs well for different levels of TWA and phase shifts in the time domain, but it is sensitive to noise and requires higher quality of electrocardiogram (ECG) signal for test. In this paper, we propose a modified correlation method (MCM) to ensure a robust and accuracy detection of TWA. Compared with CM, MCM add a stage of T-wave curve fitting before media T-wave template, and the TWA magnitude is obtained by meaning the maximum absolute difference between even and odd T-wave. Our assessment study demonstrates the improved performance of the proposed algorithm.

A REAL-TIME QT INTERVAL DETECTION ALGORITHM

2008 ◽  
Vol 08 (02) ◽  
pp. 251-263 ◽  
Author(s):  
Z. E. HADJ SLIMANE ◽  
F. BEREKSI REGUIG
Keyword(s):  
Real Time ◽  
Qt Interval ◽  
Detection Algorithm ◽  
Qrs Detection ◽  
Signal To Noise ◽  
Ecg Signals ◽  
Wave Detection ◽  
T Wave ◽  
Electrocardiogram Ecg ◽  
Ventricular Depolarization

The QT interval is the electrocardiographic representation of the duration of ventricular depolarization and repolarization. In this paper, we have developed a new real-time QT interval detection algorithm for automatically locating the onset of QRS and the end of the T wave. The algorithm consists of several steps: signal-to-noise enhancement, QRS detection, QRS onset, and T-wave end definition. The detection algorithm is tested on electrocardiogram (ECG) signals from the universal MIT-BIH Arrhythmia Database. The resulting QRS detection algorithm has a sensitivity of 99.79% and a specificity of 99.72%. The QRS onset and T-wave detection algorithm is tested using several data records from the MIT/BIH Arrhythmia Database. The results obtained are shown to be highly satisfactory.

scholarly journals Electrophysiological Mechanisms Underlying T-Wave Alternans and Their Role in Arrhythmogenesis

2021 ◽  
Vol 12 ◽  
Author(s):  
Tingting You ◽  
Cunjin Luo ◽  
Kevin Zhang ◽  
Henggui Zhang
Keyword(s):  
Heart Rate ◽  
Tissue Level ◽  
Cellular Level ◽  
Simulation Studies ◽  
Future Perspectives ◽  
Non Invasive ◽  
T Wave ◽  
Dispersion Of Repolarization ◽  
St Segment ◽  
T Wave Alternans

T-wave alternans (TWA) reflects every-other-beat alterations in the morphology of the electrocardiogram ST segment or T wave in the setting of a constant heart rate, hence, in the absence of heart rate variability. It is believed to be associated with the dispersion of repolarization and has been used as a non-invasive marker for predicting the risk of malignant cardiac arrhythmias and sudden cardiac death as numerous studies have shown. This review aims to provide up-to-date review on both experimental and simulation studies in elucidating possible mechanisms underlying the genesis of TWA at the cellular level, as well as the genesis of spatially concordant/discordant alternans at the tissue level, and their transition to cardiac arrhythmia. Recent progress and future perspectives in antiarrhythmic therapies associated with TWA are also discussed.

Abstract 17250: Quantitative T Wave Morphology Analysis in Rett Syndrome Patients

Circulation ◽  
2020 ◽  
Vol 142 (Suppl_3) ◽  
Author(s):  
Michael Collins ◽  
Hoang Nguyen ◽  
Mark Johnson ◽  
Robin Ryther ◽  
Judith Weisenberg
Keyword(s):  
Sudden Death ◽  
Rett Syndrome ◽  
Principal Component ◽  
Cardiac Repolarization ◽  
T Wave ◽  
Morphology Analysis ◽  
Abnormal Morphology ◽  
Torsades Des Pointes ◽  
Wave Morphology ◽  
Electrocardiogram Ecg

Introduction: Rett syndrome (RTT) is a genetic neurologic disorder associated with a high incidence of sudden death. Abnormal cardiac repolarization is a potential risk factor for sudden death in this population. RTT patients may have prolonged corrected QT (QTc) on electrocardiogram (ECG) that is a sensitive marker of torsades des pointes. However, other repolarization markers such as T wave morphology, the time it takes the T wave to return to baseline from peak amplitude (Tpeak - Tend), and heart rate corrected JTpeak have not been studied. Hypothesis: Rett syndrome patients have abnormal cardiac repolarization. Methods: Retrospective T wave analysis was performed using QT Guard software. T wave morphology and heterogeneity parameters of RTT patients were compared to ECGs of age and sex matched healthy controls. A composite T wave morphology score was calculated from individual feature of flatness, notching, and asymmetry; a higher score means more abnormal morphology. Heterogeneity of repolarization was represented by the principal component analysis ratio 2 (PCA-2). Results: 57 Rett patients (260 ECG) and 121 controls (134 ECG) were studied. The RTT group had longer QTc (p = 0.001) along with more abnormal T-wave morphology scores and heterogeneity parameters when compared to controls (Tables 1, 2). RTT patients without long QTc also had more abnormal morphology scores than controls (p = 0.001). Conclusion: Cardiac repolarization is diffusely abnormal in RTT even in the absence of long QTc. T wave morphology analysis may be used to detect and monitor abnormal cardiac repolarization in RTT in clinical practice.

T-wave alternans and dispersion of the QT interval as risk stratification markers in patients susceptible to sustained ventricular arrhythmias

1998 ◽  
Vol 82 (9) ◽  
pp. 1127-1129 ◽  
Author(s):  
Antonis A Armoundas ◽  
Motohisa Osaka ◽  
Theofanie Mela ◽  
David S Rosenbaum ◽  
Jeremy N Ruskin ◽  
...  
Keyword(s):  
Risk Stratification ◽  
Qt Interval ◽  
Ventricular Arrhythmias ◽  
T Wave ◽  
T Wave Alternans

T wave alternans in an in vitro canine tissue model of Brugada syndrome

2006 ◽  
Vol 291 (1) ◽  
pp. H421-H428 ◽  
Author(s):  
Hiroshi Morita ◽  
Douglas P. Zipes ◽  
John Lopshire ◽  
Shiho T. Morita ◽  
Jiashin Wu
Keyword(s):  
Right Ventricular ◽  
Brugada Syndrome ◽  
Dynamic Instability ◽  
Drug Induced ◽  
T Wave ◽  
Dispersion Of Repolarization ◽  
T Wave Alternans ◽  
The Right ◽  
T Waves

Macroscopic T wave alternans (TWA) associated with increased occurrence of ventricular arrhythmias has been reported in patients with Brugada syndrome. However, the mechanisms in this syndrome are still unclear. We evaluated the hypothesis that TWA in Brugada syndrome was caused by the dynamic instability and heterogeneity of action potentials (APs) in the right ventricle. Using an optical mapping system, we mapped APs on the epicardium or transmural surfaces of 28 isolated and arterially perfused canine right ventricular preparations having drug-induced Brugada syndrome (in μmol/l: 2.5–15 pinacidil, 5.0 terfenadine, and 5.0–13 pilsicainide). Bradycardia at cycle length (CL) of 2,632 ± 496 ms ( n = 19) induced alternating deep and shallow T waves in the transmural electrocardiogram. Compared with the shallow T waves, deep T waves were associated with epicardial APs having longer durations and larger domes. Adjacent regions having APs with alternating domes, with constant domes, and without domes coexisted simultaneously in the epicardium and caused TWA. In contrast to the alternating epicardial APs, midmyocardial and endocardial APs did not change during TWA. Alternans could be terminated by rapid (CL: 529 ± 168 ms, n = 7) or very slow (CL: 3,000 ms, n = 7) pacing. The heterogeneic APs during TWA augmented the dispersion of repolarization both within the epicardium and from the epicardium to the endocardium and caused phase 2 reentry. In this drug-induced model of Brugada syndrome, heterogeneic AP contours and dynamic alternans in the dome of right ventricular epicardial, but not midmyocardial or endocardial, APs caused TWA and heightened arrhythmogenicity in part by increasing the dispersion of repolarization.

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