Quantitative Assessment of Microvolt T‐Wave Alternans in Patients with Congestive Heart Failure

Abstract-T-wave alternans (TWA) is a cardiac phenomenon that appears in the electrocardiogram (ECG) and is associated with the mechanisms leading to sudden cardiac death (SCD). In this study, we propose the use of a multilead TWA analysis scheme that combines the Laplacian likelihood ratio (LLR) method and periodic component analysis (pCA), an eigenvalue decomposition technique whose aim is to extract the most periodic sources of the signal. The proposed scheme is evaluated in different scenarios-from synthetic signals to stress test ECGs-and is compared to other reported schemes based on the LLR method. Results demonstrate that the pCA-based scheme provides a superior ability to detect TWA than previously reported schemes, and has the potential to improve the prognostic value of testing for TWA.

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“…8,9,15 Results in section ''Synthetic Signals'' indicate that the multi-pCA scheme improves the accuracy of the amplitude estimation (Fig. 4).…”

Section: Discussionmentioning

confidence: 94%

A Multilead Scheme Based on Periodic Component Analysis for T-Wave Alternans Analysis in the ECG

et al. 2010

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“…The presence or absence of this phenomenon (i.e., a detection problem) is often the only information considered and most studies consider just the presence of TWA, regardless of its magnitude, as a clinical index. However, the magnitude of the observed TWA (i.e., an estimation problem) may also be relevant, as it has been shown that increasing TWA magnitude is associated with higher susceptibility to SCD [93]. Patterns of variation in the TWA magnitude can be seen in three domains: the distribution of alternans within the ST-T segment, the time course of TWA and the distribution of TWA in the different recorded leads.…”

Section: Ecg Markers For Characterization Of Spatio-temporal Repolmentioning

confidence: 99%

Techniques for Ventricular Repolarization Instability Assessment From the ECG

2016

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Abstract-Instabilities in ventricular repolarization have been documented to be tightly linked to arrhythmia vulnerability. Translation of the information contained in the repolarization phase of the ECG into valuable clinical decision-making tools remains challenging. This work aims at providing an overview of the last advances in the proposal and quantification of ECG-derived indices that describe repolarization properties and whose alterations are related with threatening arrhythmogenic conditions. A review of the state-of-the-art is provided, spanning from the electrophysiological basis of ventricular repolarization to its characterization on the surface ECG through a set of temporal and spatial risk markers.Index Terms-Electrophysiological basis of the ECG, ECG waves, ECG intervals, repolarization instabilities, spatial and temporal ventricular repolarization dispersion, cardiac arrhythmias, biophysical modeling of the ECG, ECG signal processing, repolarization risk markers, T wave alternans, QT variability.

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“…A stretch-related contribution to TWA is plausible, since acute volume load alters ventricular repolarization and conduction and induces premature beats (4,24). A direct contribution of myocardial disease to TWA is also plausible, since CHF patients at low SCA risk are more likely to have normal TWA, although it is unclear whether they also have less volume overload (2,9). Volume load has a complex interaction with myocardial disease and may alter arrhythmic risk differentially, whether regional or global (19,24).…”

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confidence: 99%

“…T-wave alternans (TWA) is an increasingly used ECG predictor for SCA, yet it is also abnormal in patients with CHF who do not succumb to SCA (2,13). Moreover, TWA relates to the severity of structural disease (9) or CHF (22).…”

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confidence: 99%

Acute volume overload elevates T-wave alternans magnitude

Narayan

Drinan²,

Lackey³

et al. 2007

Journal of Applied Physiology

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.-The objective of this study was to determine whether acute volume loading elevates T-wave alternans (TWA) in dogs with structurally normal hearts. TWA predicts sudden cardiac arrest in patients with left ventricular dysfunction and congestive heart failure. However, volume load and ventricular stretch may themselves precipitate arrhythmias. It is unclear to what extent volume load causes TWA. In six male mongrel dogs [25.8 kg (SD 4.2)] under general anesthesia, we measured TWA during progressive atrial pacing to 160 beats/min. Pacing was performed at baseline, at the midpoint and peak of a saline infusion designed to induce acute CHF, and then during diuresis. Dog 1 was hypothermic throughout the protocol and excluded from analysis. For dogs 2-6, 102 ml/kg (SD 30) were infused over 315 min (SD 50), causing pulmonary capillary wedge pressure to rise from 9.6 (SD 3.5) to 21.2 mmHg (SD 1.6) (P Ͻ 0.01), and heart rate variability to fall (P Ͻ 0.01). TWA magnitude (Valt) rose in all dogs with volume load (P Ͻ 0.001). Compared with baseline, TWA at peak infusion had higher magnitude [Valt 3.4 (SD 1.95) vs. 0.5 V (SD 0.35); P ϭ 0.011] and occurred at lower heart rates [128 (SD 6) vs. 151 beats/min (SD 12); P ϭ 0.008]. Net volume load was linearly related to Valt (P Ͻ 0.01), with each 10 ml/kg net volume load increasing Valt by 0.23 V. Acute volume overload elevates TWA in normal canine hearts. Although dramatic, however, this effect may contribute clinically to abnormal TWA only in patients with marked volume overload. Future studies should examine the interaction of fluid overload, myocardial disease, and arrhythmia susceptibility.

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Quantitative Assessment of Microvolt T‐Wave Alternans in Patients with Congestive Heart Failure

Abstract: Patients with nonischemic cardiomyopathy and patients with tachyarrhythmic complications have more extensive MTWA possibly reflecting more extensive myocardial damage and a higher arrhythmia propensity.

Cited by 66 publications

References 17 publications

A Multilead Scheme Based on Periodic Component Analysis for T-Wave Alternans Analysis in the ECG

A Multilead Scheme Based on Periodic Component Analysis for T-Wave Alternans Analysis in the ECG

Techniques for Ventricular Repolarization Instability Assessment From the ECG

Acute volume overload elevates T-wave alternans magnitude

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