Mechanisms of the Spatial Distribution of QT Intervals on the Epicardial and Body Surfaces

Punske, Bonnie B.; Lux, Robert L.; MacLeod, Robert S.; Fuller, Matthew; Ershler, Philip R.; Dustman, Theodore J.; Vyhmeister, Yonild; Taccardi, Bruno

doi:10.1111/j.1540-8167.1999.tb00225.x

Cited by 30 publications

(16 citation statements)

References 39 publications

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“…9 -14 A variety of studies have yielded conflicting results regarding the sensitivity of body surface dispersion measures to changes in the dispersion of myocardial repolarization. 2,4,6 The conclusions from these reports were based on in vitro or nonconcurrent recordings of body surface and epicardial activity, and just 2 of these studies 2,12 incorporated dense arrays of body surface signals (which were simulated in the latter 12 ). Using arrays of simultaneously sampled torso and epicardial electrograms in vivo, we have confirmed that changes in myocardial ARI dispersion caused by regional ventricular ischemia may not be readily identifiable by use of temporal indices derived from the 12-lead ECG.…”

Section: Discussionmentioning

confidence: 99%

“…Noninvasive body surface electrical recordings have been used to define indices thought to reflect abnormal electrophysiological substrate. 1,2 However, the reliability of body surface measures (for example, recovery time dispersion, QT dispersion, and QRST integral mapping) to accurately detect myocardial substrate is viewed as being useful, [3][4][5][6] marginal, 2,7,8 or having no predictive power. 9 -11 Indeed, recent work has shown that indices derived from simulated body surface signals were inadequate in reflecting the underlying measured epicardial activationrecovery intervals (ARIs).…”

mentioning

confidence: 99%

“…9 -11 Indeed, recent work has shown that indices derived from simulated body surface signals were inadequate in reflecting the underlying measured epicardial activationrecovery intervals (ARIs). 12 This has further called into question the clinical usefulness of body surface measures to detect dispersion of depolarization and repolarization, 13,14 although it should be noted that of the above-mentioned studies, just of four [1][2][3]12 incorporated dense-array body surface mapping, whereas the other reports were based solely on the standard 12-lead ECG.…”

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confidence: 99%

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Imaging Electrocardiographic Dispersion of Depolarization and Repolarization During Ischemia

2003

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Background-Myocardial ischemia creates abnormal electrophysiological substrates that result in life-threatening ventricular arrhythmias. Identifying patients at risk of such abnormalities by use of body surface electrical measures is controversial. We investigated the sensitivity of torso measures, recorded simultaneously with epicardial electrograms, to changes in dispersion of depolarization and repolarization during localized ventricular ischemia. Methods and Results-Ventricular epicardial electrograms were recorded from 5 anesthetized pigs with a 127-electrode sock. A controllable suture snare was used to ligate the left anterior descending coronary artery (LAD). The chest was reclosed, and a vest with 256 ECG electrodes was fitted to the torso. Simultaneous arrays of epicardial electrograms and torso ECGs were recorded during LAD occlusion and reperfusion. Activation-recovery intervals (ARIs), QT u and RT u dispersion (where u indicates upstroke), and QRST integrals were calculated, and these data were fitted to anatomically customized computational models of the swine ventricular epicardium and torso. LAD occlusion caused the epicardial ARI dispersion to steadily increase, whereas the location of shortest ARI shifted from the posterobasal ventricular tissue (control) to the anteroapical myocardium, distal to the suture snare. These changes were associated with a steady increase in the torso RT u dispersion as the shortest RT u interval moved from the right shoulder (control) to the sternum. QT u and RT u dispersion determined from the 12-lead ECG did not consistently reflect the myocardial changes. Conclusions-Although changes in myocardial repolarization dispersion resulting from localized ischemia are not reliably reflected in temporal indices derived from the 12-lead ECG, they can be readily identified with high-resolution torso ECG mapping.

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Section: Discussionmentioning

confidence: 99%

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Imaging Electrocardiographic Dispersion of Depolarization and Repolarization During Ischemia

2003

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“…QT dispersion has been used to characterize myocardial repolarization, but recent studies showed that QT dispersion is unrelated, 28,29 so further study will be required to identify the clinical importance and electrophysiological role of QT dispersion.…”

Section: Discussionmentioning

confidence: 99%

Opening of KATP Channel Attenuates the Increase in QT Dispersion Produced by the First Balloon Inflation During Coronary Angioplasty.

Ashikaga

Nishizaki

Arita

et al. 2002

Circ J

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ethal ventricular arrhythmias, which occur more frequently at the first balloon inflation than with subsequent procedures, occur in 1.5-4.4% of patients undergoing percutaneous transluminal coronary angioplasty (PTCA). [1][2][3][4][5][6] Moreover, these arrhythmias develop more often with PTCA of the left anterior descending coronary artery (LAD). 6 Increased QT dispersion is an useful marker of lethal ventricular arrhythmias, 6 but the mechanism and prevention of the lethal ventricular arrhythmias complicating PTCA have not been elucidated.A previous study reported that repeated coronary occlusions during PTCA reduces the occurrence of ventricular arrhythmias, 7 and these phenomenon have been attributed to ischemic preconditioning through the opening of the KATP channel. Tomai et al demonstrated that ischemic preconditioning during PTCA was prevented by glibenclamide, a selective KATP channel blocker, 8 and Garrat et al demonstrated an increased mortality rate in diabetic patients given sulfonylurea during PTCA. 9 Cole et al demonstrated in guinea pigs that blockade of the KATP channel with glibenclamide worsened the electrical and mechanical

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“…8 -10 Furthermore, the QTd measure was shown to depend on variables not related to myocardial repolarization. 11 These factors have combined to call into question the clinical usefulness of QTd. 12,13 A major assumption of QTd and QRST integral maps is that body-surface potentials preserve the spatial distribution of epicardial potentials and associated cardiac electrical sources.…”

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confidence: 99%

Imaging Dispersion of Myocardial Repolarization, I

et al. 2001

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Background-Body-surface ECG measures (QT dispersion [QTd], QRST integrals) have been used as indices of myocardial repolarization abnormalities with the goal of identifying patients at risk of fatal arrhythmias. The clinical utility of these measures has been questioned. We investigate the complex relationship between epicardial and body-surface potentials in the context of regionally abnormal myocardial repolarization. Methods and Results-Epicardial potentials were recorded with a 224-electrode sock from an open-chest dog during control, regional epicardial warming, cooling, and adjacent warming and cooling to induce localized alterations in myocardial repolarization and regions of increased repolarization dispersion. Body-surface potentials were generated from these epicardial potentials in a human torso model. Epicardial estimates of repolarization (activation recovery intervals [ARIs] and QRST integrals) were evaluated for their ability to identify regions with increased repolarization dispersion. Body-surface QRST integrals and QTd in 12-lead ECG and 64-lead body-surface potential maps were evaluated for their ability to detect increased dispersion of myocardial repolarization. Epicardial ARI and QRST integral maps successfully located epicardial regions with increased dispersion of repolarization. The increased dispersion was not consistently reflected in the 12-lead or 64-lead ECG QTd or in the body-surface QRST integral maps. Conclusions-This study demonstrates the inadequacy of body-surface measures that are thought to reflect myocardial dispersion of repolarization. In contrast, measures based on epicardial electrograms (ARI or epicardial QRST integral maps) provide physiologically relevant information about myocardial repolarization and can locate regions of increased dispersion.

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Mechanisms of the Spatial Distribution of QT Intervals on the Epicardial and Body Surfaces

Cited by 30 publications

References 39 publications

Imaging Electrocardiographic Dispersion of Depolarization and Repolarization During Ischemia

Imaging Electrocardiographic Dispersion of Depolarization and Repolarization During Ischemia

Opening of KATP Channel Attenuates the Increase in QT Dispersion Produced by the First Balloon Inflation During Coronary Angioplasty.

Imaging Dispersion of Myocardial Repolarization, I

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