Vectorcardiography shows cardiac memory and repolarization heterogeneity after ablation of accessory pathways not apparent on ECG

Wecke, Liliane; Poçi, Dritan; Schwieler, Jonas; Johansson, Birgitta; Edvardsson, Nils; Lundahl, Gunilla; Bergfeldt, Lennart

doi:10.1016/j.ijcard.2011.10.106

Cited by 18 publications

(10 citation statements)

References 20 publications

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“…Our laboratory has previously demonstrated that vectorcardiographic (VCG) recordings based on the Frank (X, Y, Z) lead system provide QT measurements that have greater diagnostic precision in individuals affected with LQTS than manual and automatic measurement in the standard 12-lead ECG (6, 7). Furthermore, VCG has proven more sensitive to VR alterations than conventional ECG in human studies of cardiac memory development, whether induced by ventricular pacing or following Wolff-Parkinson-White ablation (31,32). VCG provides information about other aspects of VR in addition to its duration.…”

mentioning

confidence: 99%

Electrophysiological phenotype in the LQTS mutations Y111C and R518X in the KCNQ1 gene

Diamant

Vahedi

Winbo

et al. 2013

Journal of Applied Physiology

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Long QT syndrome is the prototypical disorder of ventricular repolarization (VR), and a genotype-phenotype relation is postulated. Furthermore, although increased VR heterogeneity (dispersion) may be important in the arrhythmogenicity in long QT syndrome, this hypothesis has not been evaluated in humans and cannot be tested by conventional electrocardiography. In contrast, vectorcardiography allows assessment of VR heterogeneity and is more sensitive to VR alterations than electrocardiography. Therefore, vectorcardiography was used to compare the electrophysiological phenotypes of two mutations in the LQT1 gene with different in vitro biophysical properties, and with LQT2 mutation carriers and healthy control subjects. We included 99 LQT1 gene mutation carriers (57 Y111C, 42 R518X) and 19 LQT2 gene mutation carriers. Potassium channel function is in vitro most severely impaired in Y111C. The control group consisted of 121 healthy subjects. QRS, QT, and T-peak to T-end (Tp-e) intervals, measures of the QRS vector and T vector and their relationship, and T-loop morphology parameters were compared at rest. Apart from a longer heart rate-corrected QT interval (QT heart rate corrected according to Bazett) in Y111C mutation carriers, there were no significant differences between the two LQT1 mutations. No signs of increased VR heterogeneity were observed among the LQT1 and LQT2 mutation carriers. QT heart rate corrected according to Bazett and Tp-e were longer, and the Tp-e-to-QT ratio greater in LQT2 than in LQT1 and the control group. In conclusion, there was a marked discrepancy between in vitro potassium channel function and in vivo electrophysiological properties in these two LQT1 mutations. Together with previous observations of the relatively low risk for clinical events in Y111C mutation carriers, our results indicate need for cautiousness in predicting in vivo electrophysiological properties and the propensity for clinical events based on in vitro assessment of ion channel function alone.

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confidence: 99%

Electrophysiological phenotype in the LQTS mutations Y111C and R518X in the KCNQ1 gene

Diamant

Vahedi

Winbo

et al. 2013

Journal of Applied Physiology

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“…VCG provides both 3D QRST-derived "conventional" ECG measures [e.g., the QRS, QT, and T-peak to T-end (Tp-e) intervals], and information on other global aspects of VR, as reflected by T vector and T-vector loop morphology parameters. VCG also outlines the 3D relationship between depolarization and repolarization forces (3,19,24,25,29,30,31) and has proven superior to ECG for detection of VR changes in the long QT syndrome and of cardiac memory, as induced by ventricular pacing or appearing after Wolff-Parkinson-White ablation (6,30,31).…”

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confidence: 99%

Vectorcardiography analysis of the repolarization response to pharmacologically induced autonomic nervous system modulation in healthy subjects

Vahedi

Odenstedt

Hartford

et al. 2012

Journal of Applied Physiology

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Autonomic nervous system activity is essential for regulation of ventricular repolarization (VR) and plays an important role in several arrhythmogenic conditions. This study in 31 healthy adult subjects (16 men, 15 women) evaluated the VR response to pharmacologically modulated autonomic nervous system activity applying vectorcardiography (VCG) analysis. During continuous VCG recording, 0.01-0.1 μg·kg(-1)·min(-1) isoprenaline (Iso) was infused at an increasing flow rate until three targeted heart rates (HR) were reached. After Iso washout, one intravenous bolus of 0.04 mg/kg atropine was given followed by an intravenous bolus of 0.2 mg/kg propranolol. A 5-min steady-state VCG recording was analyzed for each of the seven phases (including baseline 1 and 2). Furthermore, during the first 4 min following atropine, six periods of 10-s VCG were selected for subanalysis to evaluate the time course of change. The analysis included QRS, QT, and T-peak to T-end intervals, measures of the QRS and T vectors and their relation, as well as T-loop morphology parameters. By increasing HR, Iso infusion decreased HR dependent parameters reflecting total heterogeneity of VR (T area) and action potential morphology (ventricular gradient). In contrast, Iso prolonged QT HR corrected according to Bazett and increased the T-peak to T-end-to-QT ratio to levels observed in arrhythmogenic conditions. HR acceleration after atropine was accompanied by a transient paradoxical QT prolongation and delayed HR adaptation of T area and ventricular gradient. In addition to the expected HR adaptation, the VR response to β-adrenoceptor stimulation with Iso and to muscarinic receptor blockade with atropine thus included alterations previously observed in congenital and acquired long QT syndromes, demonstrating substantial overlap between physiological and pathophysiological electrophysiology.

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“…Azimuth of initial 30 ms QRS vector is the angle between the projected of initial 30 ms QRS vector on the horizontal plane (X-Z) and the left extremity of the X-axis, zero being the vector pointed to the left. Forward vector motions are defined as 0-180°, and backward vector motions as 0-180°, [10][11][12] see Figure 1B. (2) Terminal QRS vector: spatial orientation (elevation and azimuth) of terminal 20 ms QRS vector was observed. The measurement method of terminal 20 ms QRS vector was same as initial 30 ms QRS vector.…”

Section: Measured Valuementioning

confidence: 99%

Effects of Preexcitation Syndrome on Terminal QRS Vector Observed in Spatial Vector

Wang

Yang

Liu

et al. 2016

Noninvasive Electrocardiol

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(1) Both initial and terminal QRS vector are affected by the antegrade conduction of AP. The change of terminal QRS vector is related to the AP location and delta vector. (2) The effect of preexcitation syndrome on QRS terminal vector is shown as more intuitive and easy in spatial vector by comparison with electrocardiogram, which is helpful for the diagnosis of atypical preexcitation and localization of AP.

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Vectorcardiography shows cardiac memory and repolarization heterogeneity after ablation of accessory pathways not apparent on ECG

Cited by 18 publications

References 20 publications

Electrophysiological phenotype in the LQTS mutations Y111C and R518X in the KCNQ1 gene

Electrophysiological phenotype in the LQTS mutations Y111C and R518X in the KCNQ1 gene

Vectorcardiography analysis of the repolarization response to pharmacologically induced autonomic nervous system modulation in healthy subjects

Effects of Preexcitation Syndrome on Terminal QRS Vector Observed in Spatial Vector

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