The U wave in the electrocardiogram: A solution for a 100-year-old riddle

Eck, Henk J. Ritsema van; Kors, Jan A.; Herpen, Gerard van

doi:10.1016/j.cardiores.2005.04.010

Cited by 40 publications

(29 citation statements)

References 24 publications

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“…This results in a significant change in the shape of the T-wave, as shown in Fig. 3, panel IV, as well as in previous studies (Yan et al, 1998b;Gima and Rudy, 2002;Idriss and Wolf, 2004;Ritsema van Eck et al, 2005). It should be noted however, that, while there is a large body of evidence supporting the existence of transmural heterogeneities in ionic currents and electrophysiological properties of ventricular tissue, some experimental studies have documented little or no transmural differences in APD in vivo (Anyukhovsky et al, 1996(Anyukhovsky et al, ,1999Taggart et al, 2001;Conrath et al;.…”

Section: Transmural Electrophysiological Heterogeneities In the Ventrsupporting

confidence: 76%

The role of transmural ventricular heterogeneities in cardiac vulnerability to electric shocks

Maharaj

Blake

Trayanova

et al. 2008

Progress in Biophysics and Molecular Biology

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Transmural electrophysiological heterogeneities have been shown to contribute to arrhythmia induction in the heart; however, their role in defibrillation failure has never been examined. The goal of this study is to investigate how transmural heterogeneities in ionic currents and gap-junctional coupling contribute to arrhythmia generation following defibrillation strength shocks. This study used a 3D anatomically realistic bidomain model of the rabbit ventricles. Transmural heterogeneity in ionic currents and reduced sub-epicardial intercellular coupling were incorporated based on experimental data. The ventricles were paced apically, and truncated-exponential monophasic shocks of varying strength and timing were applied via large external electrodes. Simulations demonstrate that inclusion of transmural heterogeneity in ionic currents results in an increase in vulnerability to shocks, reflected in the increased upper limit of vulnerability, ULV, and the enlarged vulnerable window, VW. These changes in vulnerability stem from increased post-shock dispersion in repolarisation as it increases the likelihood of establishment of re-entrant circuits. In contrast, reduced sub-epicardial coupling results in decrease in both ULV and VW. This decrease is caused by altered virtual electrode polarisation around the region of sub-epicardal uncoupling, and specifically, by the increase in (1) the amount of positively polarised myocardium at shock-end and (2) the spatial extent of post-shock wavefronts.

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Section: Transmural Electrophysiological Heterogeneities In the Ventrsupporting

confidence: 76%

The role of transmural ventricular heterogeneities in cardiac vulnerability to electric shocks

Maharaj

Blake

Trayanova

et al. 2008

Progress in Biophysics and Molecular Biology

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“…Although it has been suggested that the U wave may represent late repolarization activities of myocytes [6], [7], the present study indicates that substantial information on ischemic changes for our inverse method is included in the QRST or STT intervals. Comparison of the results for both intervals can be helpful in evaluating (qualifying) the stability and reliability of the solution.…”

Section: Discussion/conclusionmentioning

confidence: 72%

“…The U-wave is explained in [5] by the presence of after-potentials on the cardiac action potentials (caused by mechanical stress of cardiac cells during systolic phase) associated with ventricular wall motion. According to other studies [6], [7] T and U waves together represent the repolarization period. In such case, inclusion of the U wave into the evaluated interval would be desirable.…”

Section: Introductionmentioning

confidence: 95%

Identification of Ischemic Lesions Based on Difference Integral Maps, Comparison of Several ECG Intervals

Svehlikova¹,

Kania²,

Turzová³

et al. 2009

Measurement Science Review

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Ischemic changes in small areas of myocardium can be detected from difference integral maps computed from body surface potentials measured on the same subject in situations with and without manifestation of ischemia. The proposed method for their detection is the inverse solution with 2 dipoles. Surface potentials were recorded at rest and during stress on 10 patients and 3 healthy subjects. Difference integral maps were computed for 4 intervals of integration of electrocardiographic signal (QRST, QRSU, STT and STU) and their properties and applicability as input data for inverse identification of ischemic lesions were compared. The results showed that better (more reliable) inverse solutions can be obtained from difference integral maps computed either from QRST or from STT interval of integration. The average correlation between these maps was 97%. The use of the end of U wave instead of the end of T wave for interval of integration did not improve the results.

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“…Hexagonal (Hex) grid methods are of interest in many research studies: (Pickering,1986) on direct method, (Makarov, Mararov & Moskal'kov, 1993) giving a formula without proof, (Bystrytskyi & Mosklkov, 2001) on seven-point method on rectangular grid with explicit form of eigenpairs, (Zhou & Fulton, 2009) with periodic boundary condition (BC), (Heikes & Randall, 1995, part I,II) and (Heikes, Randall & Konor, 2013) on numerical modeling in spherical coordinates, (van Eck & Kors, 2005) on action potential in heart modeling via algebraic method without using diffusion in form of differential equation, (Nickovic,Gavrilov & Tosic, 2002) showing advantages of Hex grids over commonly used square grids for use in atmospheric and ocean models. In the article by (Lee,Tien,Luo and Luk,2014), Hex grid finite difference (FD) methods are derived in a finite volume (FV) approach involving standard Laplacian, and used in the simulation of electrical wave phenomena propagated in two-dimensional reversed-C type cardiac tissues, exhibiting both linear and spiral waves more efficiently than similar computation carried on rectangular FVs.…”

Section: Introductionmentioning

confidence: 99%

Symmetric Boundary Condition for Laplacian on Net of Regular Hexagons

Lee¹

2017

JMR

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Hexagonal grid methods are found useful in many research works, including numerical modeling in spherical coordinates, in atmospheric and ocean models, and simulation of electrical wave phenomena in cardiac tissues. Almost all of these used standard Laplacian and mostly on one configuration of regular hexagons. In this work, discrete symmetric boundary condition and energy product for anisotropic Laplacian are investigated firstly on general net of regular hexagons, and then generalized to its most extent in two-or three-dimensional cell-center finite difference applications up to the usage of symmetric stencil in central differences. For analysis of Laplacian related applications, this provides with an approach in addition to the M-matrix theory, series method, functional interpolations and Fourier vectors.

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The U wave in the electrocardiogram: A solution for a 100-year-old riddle

Abstract: T and U form a continuum. Together they are the resultant of one and the same process of repolarization of the ventricular myocardium. This has implications for the measurement of QT duration and for safety testing of drug-induced QT prolongation.

Cited by 40 publications

References 24 publications

The role of transmural ventricular heterogeneities in cardiac vulnerability to electric shocks

The role of transmural ventricular heterogeneities in cardiac vulnerability to electric shocks

Identification of Ischemic Lesions Based on Difference Integral Maps, Comparison of Several ECG Intervals

Symmetric Boundary Condition for Laplacian on Net of Regular Hexagons

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