T‐Wave Morphology Parameters Based on Principal Component Analysis Reproducibility and Dependence on T−Offset Position

Extramiana, Fabrice; Haggui, Abdeddayem; Maison‐Blanche, Pierre; Dubois, Rémi; Takatsuki, Seiji; Beaufils, Philippe; Leenhardt, Antoine

doi:10.1111/j.1542-474x.2007.00185.x

Cited by 18 publications

(8 citation statements)

References 37 publications

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“…VCG loop morphology can be characterized by the direction and amplitude of the instantaneous initial spatial [3] and maximum “peak” and “mean” vectors of the loop [4]. The “roundness” or principal shape of the loop has been described as the ratio of VCG loop height and width [5], or as the ratio of the second and first principal components of the orthogonal eigenvectors [6]. It has been shown that normal hearts have QRS loops which stay primarily in a single “main,” or “preferential” plane [7; 8].…”

Section: Introductionmentioning

confidence: 99%

Quantitative Assessment of Vectorcardiographic Loop Morphology

Sedaghat

Ghafoori

Waks

et al. 2016

Journal of Electrocardiology

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Vectorcardiography (VCG), developed 100 years ago, characterizes clinically important electrophysiological properties of the heart. In this study, VCG QRS loop roundness, planarity, thickness, rotational angle, and dihedral angle were measured in 81 healthy control subjects (39.0±14.2y; 51.8% male; 94% white), and 8 patients with infarct-cardiomyopathy and sustained monomorphic ventricular tachycardia (VT) (68.0±7.8y, 37.5% male). The angle between two consecutive QRS vectors was defined as the rotational angle, while dihedral angle quantified planar alteration over the QRS loop. In VT subjects, planarity index decreased (0.63±0.22 vs. 0.88±0.10; P=0.014), and dihedral angle was significantly more variable (variance of dihedral angle, median (IQR): 897(575–1450) vs. 542(343–773); P=0.029; rMSSD: 47.7±12.7 vs. 35.1±13.1; P=0.027). Abnormal electrophysiological substrate in VT patients is characterized by the appearance of QRS loop folding, likely due to local conduction block. The presence of fragmented QRS complexes on the 12-lead ECG had low sensitivity (31%) for detecting QRS loop folding on the VCG.

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Section: Introductionmentioning

confidence: 99%

Quantitative Assessment of Vectorcardiographic Loop Morphology

Sedaghat

Ghafoori

Waks

et al. 2016

Journal of Electrocardiology

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“…20,21 Principal component analysis also was reported to be useful in prediction of cardiovascular mortality. 22 So far, ICA has not been applied for analysis of the repolarization process in LQTS.…”

Section: Discussionmentioning

confidence: 99%

“…As a multivariate analysis of inhomogeneity of ventricular repolarization, the principal component analysis has been applied for the assessment of T-wave morphology in LQTS by some investigators, 20,21 the results of which demonstrated its usefulness in distinguishing abnormal from normal repolarization processes such that a high second/first eigenvector ratio predicts increased inhomogeneous repolarization. 20,21 Principal component analysis also was reported to be useful in prediction of cardiovascular mortality.…”

Section: Discussionmentioning

confidence: 99%

Detection of Extra Components of T Wave by Independent Component Analysis in Congenital Long-QT Syndrome

Horigome

Ishikawa²,

Shiono³

et al. 2011

Circ: Arrhythmia and Electrophysiology

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Background-The main ECG criteria for the diagnosis of long-QT syndrome (LQTS) include abnormal T-wave morphology as well as prolonged QT interval. The T wave in LQTS probably includes additional components of the myocardial repolarization process, which are derived from aberrant ion currents. We investigated whether independent component analysis (ICA) can extract such abnormal repolarization components. Methods and Results-Digital ECG data were obtained as a time series from 10 channels using 20 surface electrodes in 22 patients with genetically confirmed LQTS type 1 (LQT1) and 30 normal subjects. In each case, T-wave area was analyzed by radical ICA after noise reduction by the wavelet thresholding method. Furthermore, inverse ICA was applied to determine the origin of each independent component (IC). Radical ICA revealed that a T-wave consisted of 4 basic ICs in all control subjects, whereas Ն5 (mostly 6) ICs were identified in all 22 patients with LQT1. The extra ICs, which were not evident in normal subjects, were assumed to contribute to the formation of abnormal T-wave morphology. The extra ICs were identified even in patients with normal QTc values and in those taking ␤-blockers. Inverse ICA indicated that the additional ICs originate predominantly from the late phase of the T wave of the left ventricle. Conclusions-Extra ICs appear during repolarization in all patients with LQT1 but not in normal subjects. ICA is a potentially useful multivariate statistical method to differentiate patients with LQT1 from normal subjects. (Circ Arrhythm Electrophysiol. 2011;4:456-464.)

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“…Spatial T-loop roundness was quantified via principal component analysis (PCA)[12]. For each T loop, the two most significant components accounted for the length and width of the loop, respectively.…”

Section: Methodsmentioning

confidence: 99%

Beat-to-beat determinants of the beat-to-beat temporal and spatial variability of repolarization

Feeny

Tereshchenko

2016

Journal of Electrocardiology

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Background The goal of this study was to compare the time series predictors of beat-to-beat variability in repolarization in healthy individuals. Methods Spatial QRS- and T-vector amplitudes, spatial QRS-T, RR’ and TT’ angles, RR’ and QT intervals, and QRS- and T-loop roundness were measured on 453 consecutive sinus beats in 168 healthy subjects (mean age 39.8±15.6 y; 50% men; 93% white). Panel time-series regression models were adjusted by age, sex, and race. Appropriate time series of ECG metrics served as predictors and outcomes. Results Increase in T-loop roundness index by 0.1 was associated with 1.1° (95%CI 0.9–2.2; P=0.048) increase in corresponding TT’ angle. One unit increase in a respiration index was associated with 4 ms (95%CI 0.6–7.0; P=0.021) increase in QT interval. Conclusions Spatial TT’ angle and beat-to-beat variability in T-loop roundness represent intrinsic measures of repolarization variability. QT interval variability characterizes the effect of respiration and heart rate variability.

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T‐Wave Morphology Parameters Based on Principal Component Analysis Reproducibility and Dependence on T−Offset Position

Cited by 18 publications

References 37 publications

Quantitative Assessment of Vectorcardiographic Loop Morphology

Quantitative Assessment of Vectorcardiographic Loop Morphology

Detection of Extra Components of T Wave by Independent Component Analysis in Congenital Long-QT Syndrome

Beat-to-beat determinants of the beat-to-beat temporal and spatial variability of repolarization

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