Effect of Heart Rate on Ventricular Repolarization in Healthy Individuals Applying Vectorcardiographic T Vector and T Vector Loop Analysis

Vahedi, Farzad; Haney, Michael; Jensen, Steen M.; Näslund, Ulf; Bergfeldt, Lennart

doi:10.1111/j.1542-474x.2011.00444.x

Cited by 19 publications

(26 citation statements)

References 29 publications

(46 reference statements)

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“…The phenotypic expression of the mutations on the surface electrocardiogram (ECG) has been widely reported using multiple quantitative approaches: T wave morphology 19,20,21 , T wave lability 22,23,24 , and QT adaptation to heart rate changes. 25 These methods were primarily designed to improve the diagnosis of LQTS, and to elucidate arrhythmogenic mechanisms leading to the frequent life-threatening cardiac events in the LQTS patients.…”

Section: Iv-discussionmentioning

confidence: 99%

Measure of the QT–RR Dynamic Coupling in Patients with the Long QT Syndrome

Halámek¹,

Couderc²,

Jurák³

et al. 2012

Noninvasive Electrocardiol

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Background The patients with the long QT syndrome type-1 (LQT-1) have an impaired adaptation of the QT interval to heart rate changes. Yet, the description of the dynamic QT/RR coupling in genotyped LQT-1 has never been thoroughly investigated. Method We propose a method to model the dynamic QT/RR coupling by defining a transfer function characterizing the relationship between a QT interval and its previous RR intervals measured from ambulatory Holter recordings. Three parameters are used to characterize the QT/RR coupling: a fast gain (GainF), a slow gain (GainL), and a time constant (τ). We investigated the values of these parameters across genders, and in genotyped LQT-1 patients with normal QTc interval duration (QTc<470 ms). Results The QT/RR dynamic profiles are significantly different between LQT-1 patients (97) and controls (154): LQT-1 have longer QTc interval (453±35 vs. 384±26 ms, p<0.0001), and an increased dependency of the QT interval to previous RR changes revealed by a larger GainL (0.22±0.06 vs. 0.18±0.07, p<0.0001) and GainF (0.05±0.02 vs. 0.03±0.01, p<0.0001). Importantly, LQT-1 patients have a faster QT dynamic response to previous RR changes described by τ: 122±44 vs. 172±92 beats (p<0.0001). This faster QT dynamic response of the QT-RR dynamic coupling remained in LQT-1 patients with QTc in a normal range (<430 ms). Conclusions The measurement of QT/RR dynamic coupling could be used in patients suspected to carry a concealed form of the LQT-1 syndrome, or to provide insights into the types of arrhythmogenic triggers a patient may be prone to.

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Section: Iv-discussionmentioning

confidence: 99%

Measure of the QT–RR Dynamic Coupling in Patients with the Long QT Syndrome

Halámek¹,

Couderc²,

Jurák³

et al. 2012

Noninvasive Electrocardiol

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“…Thus, TCRT is influenced by HR. Vahedi et al [88] also found that some computed VCG parameters (QRS area , T area , and T amplitude ) were also influenced by HR, where a decrease in heterogeneity of ventricular activity was observed due to increased HR.…”

Section: Heart Rate Dependencymentioning

confidence: 92%

“…The relationship between HR and VCG-based parameters has been investigated by a few studies [50,76,88]. Some of the studies demonstrated that the VCG parameters are dependent on the HR.…”

Section: Heart Rate Dependencymentioning

confidence: 99%

“…Spatial QRS-T angle Healthy school-age children Male (n = 348) Female (n = 298) Significantly higher spatial QRS-T angle was found in boys compared to girls (p = 0.031), which shows that the direction of depolarization and repolarization for boys appears to be close to each other. [88] 1. Azimuth and elevation Patients with structurally normal hearts (n = 19) Significantly increased elevation and azimuthal orientation was observed with increased HR, which indicates that the T-wave vector appears to move slightly upward and forward.…”

Section: Beat-to-beat Vcg-based Parametersmentioning

confidence: 99%

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A review of beat-to-beat vectorcardiographic (VCG) parameters for analyzing repolarization variability in ECG signals

Hasan¹,

Abbott²

2016

Biomedical Engineering / Biomedizinische Technik

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Elevated ventricular repolarization lability is believed to be linked to the risk of ventricular tachycardia/ventricular fibrillation. However, ventricular repolarization is a complex electrical phenomenon, and abnormalities in ventricular repolarization are not completely understood. To evaluate repolarization lability, vectorcardiography (VCG) is an alternative approach where the electrocardiographic (ECG) signal can be considered as possessing both magnitude and direction. Recent research has shown that VCG is advantageous over ECG signal analysis for identification of repolarization abnormality. One of the key reasons is that the VCG approach does not rely on exact identification of the T-wave offset, which improves the reproducibility of the VCG technique. However, beat-to-beat variability in VCG is an emerging area for the investigation of repolarization abnormality though not yet fully realized. Therefore, the purpose of this review is to explore the techniques, findings, and efficacy of beat-to-beat VCG parameters for analyzing repolarization lability, which may have potential utility for further study.

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“…Abnormalities in T vector magnitude and orientation were found to be markers of altered ventricular repolarization in post-MI patients [11][12][13]. The present study aims to identify patients after MI using T vector and loop characteristics, especially those without diagnostic conventional ECG findings.…”

Section: Introductionmentioning

confidence: 96%

T Vector and Loop Characteristics Improve Detection of Myocardial Injury After Infarction

et al. 2015

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Electrocardiography (ECG) is widely used to detect myocardial injury. ECG recordings after subendocardial, non-ST-elevation myocardial infarction (MI) may lack striking infarct patterns. A vectorcardiogram (VCG) of the T wave is a three-dimensional characterization of the ventricular repolarization and identifies abnormalities at an advanced level of analysis, which would normally be done manually from conventional ECG. Several parameters describing T vector loop morphology and T vector spatial orientation are examined with regard to their suitability for late MI detection. The discriminatory performance of VCG analysis is compared to that of conventional ECG analysis in identifying post-MI patients. T vector and T loop parameters as well as infarct indicators of the ECG recordings were calculated for 114 subjects: 59 patients (42 males; mean age: 54 years) 15 days after MI (11.9 ± 6.9 d) and 55 healthy controls (27 males; mean age: 49 years). ECG infarct indicators correctly identified 75.2 % of patients, while T vector and loop parameters correctly identified 83.2 % of patients. Discrimination analysis revealed a sensitivity of 66.7 % and a specificity of 77.4 % for conventional ECG, and a sensitivity of 71.7 % and a specificity of 88.7 % for the VCG parameters. T vector and loop characteristics were superior to conventional ECG in separating patients from controls. T vector ECG can improve the detection of myocardial injury and is applicable to the analysis of cardiac repolarization.

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Effect of Heart Rate on Ventricular Repolarization in Healthy Individuals Applying Vectorcardiographic T Vector and T Vector Loop Analysis

Cited by 19 publications

References 29 publications

Measure of the QT–RR Dynamic Coupling in Patients with the Long QT Syndrome

Measure of the QT–RR Dynamic Coupling in Patients with the Long QT Syndrome

A review of beat-to-beat vectorcardiographic (VCG) parameters for analyzing repolarization variability in ECG signals

T Vector and Loop Characteristics Improve Detection of Myocardial Injury After Infarction

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