Spatial Distribution of QT Intervals: An Alternative Approach to QT Dispersion

Leeuwen, P. van; Hailer, Birgit; Wehr, M

doi:10.1111/j.1540-8159.1996.tb03248.x

Cited by 38 publications

(20 citation statements)

References 13 publications

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“…The evaluation of spatial QT dispersion on MCG, reflecting regional heterogeneity of repolarization, may improve the identification of CAD patients. 18, 38 In this study, we demonstrated not only that the patients with significant CAD had significantly higher prevalence of early occurrence of +T-wave propagation and increased heterogeneity (QTc dispersion and SI-QTc), but also that the repolarization heterogeneity index has superior diagnostic accuracy to T-wave propagation mapping in the patients with suspected CAD (0.79 vs. 0.65; P=0.036).…”

Section: Resultsmentioning

confidence: 72%

Usefulness of Magnetocardiography to Detect Coronary Artery Disease and Cardiac Allograft Vasculopathy

Lee

Liu

et al. 2013

Circ J

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Background: Electrophysiological information as well as anatomic information are important for the detection of coronary artery lesions. The aim of this study was to assess the efficacy of resting magnetocardiography (MCG) in stable coronary artery disease (CAD) and cardiac allograft vasculopathy (CAV). Methods and Results:MCG and coronary angiography were performed within 1 month in 75 patients with suspected CAD and in 26 subjects after orthotopic heart transplantation (OHT). Plaque volumes were additionally measured on intravascular ultrasound in OHT recipients. The spatially distributed QTc interval maps were constructed with 64-channel MCG. A T-wave propagation map and QTc heterogeneity index including QTc dispersion and smoothness index of QTc (SI-QTc) were derived for ischemia detection and localization. CAD patients had higher QTc dispersion and SI-QTc. Receiver operating characteristic curve analysis identified SI-QTc ≥9 ms, QTc dispersion ≥79 ms as the optimal cut-off for detecting CAD (diagnostic accuracy, 0.7953, 0.7819), better than T-wave propagation (0.6594, P<0.05). There was no significant difference of QTc dispersion between CAD and OHT subjects. In OHT recipients, QTc dispersion positively correlated with plaque volume, and SI-QTc progressively increased after transplantation. Using T-wave propagation mapping, regionally increased dispersion could be demonstrated in CAD patients, but increased dispersion was noted in fewer OHT recipients. Conclusions:MCG is clinically feasible as a non-invasive tool for diagnosis of CAD, and could be used as a surrogate marker of CAV. (Circ J 2013; 77: 1783 -1790

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Section: Resultsmentioning

confidence: 72%

Usefulness of Magnetocardiography to Detect Coronary Artery Disease and Cardiac Allograft Vasculopathy

Lee

Liu

et al. 2013

Circ J

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“…ANG II-induced electrical remodeling is part of the pathophysiological process in hypertensive heart disease and accounts for an increased arrhythmia burden in these patients. Several clinical CMFM studies suggested that multichannel CMFM systems can detect an increased risk in life-threatening arrhythmias (18,19,34). We believe the perspectives of the CMFM technique lie in determining nonhomogeneous aspects of depolarization and repolarization before the conventional ECG can detect these changes.…”

Section: Discussionmentioning

confidence: 99%

Angiotensin II-induced sudden arrhythmic death and electrical remodeling

Fischer

Dechend²,

Gapelyuk³

et al. 2007

American Journal of Physiology-Heart and Circulatory Physiology

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Rats harboring the human renin and angiotensinogen genes (dTGR) feature angiotensin (ANG) II/ hypertension-induced cardiac damage and die suddenly between wk 7 and 8. We observed by electrocardiogram (ECG) telemetry that ventricular tachycardia (VT) is a common terminal event in these animals. Our aim was to investigate electrical remodeling. We used ECG telemetry, noninvasive cardiac magnetic field mapping (CMFM) at wk 5 and 7, and performed in vivo programmed electrical stimulation at wk 7. We also investigated whether or not losartan (Los; 30 mg ⅐ kg Ϫ1 ⅐ day Ϫ1 ) would prevent electrical remodeling. Cardiac hypertrophy and systolic blood pressure progressively increased in dTGR compared with Sprague-Dawley (SD) controls. Already by wk 5, untreated dTGR showed increased perivascular and interstitial fibrosis, connective tissue growth factor expression, and monocyte infiltration compared with SD rats, differences that progressed through time. Left-ventricular mRNA expression of potassium channel subunit Kv4.3 and gap-junction protein connexin 43 were significantly reduced in dTGR compared with Los-treated dTGR and SD. CMFM showed that depolarization and repolarization were prolonged and inhomogeneous. Los ameliorated all disturbances. VT could be induced in 88% of dTGR but only in 33% of Los-treated dTGR and could not be induced in SD. Untreated dTGR show electrical remodeling and probably die from VT. Los treatment reduces myocardial remodeling and predisposition to arrhythmias. ANG II target organ damage induces VT. magnetocardiography; noninvasive mapping; double-transgenic rat model; in vivo electrophysiological study ELECTRICAL REMODELING INVOLVES acquired changes in cardiac structure or function that promote the occurrence of atrial or ventricular cardiac arrhythmias (22). On the molecular level, electrical remodeling involves changes in function and expression of membrane ion channels, gap-junction proteins, Ca 2ϩ -cycling proteins, and extracellular matrix composition. All these factors predispose to arrhythmogenic mechanisms such as early and delayed afterdepolarizations and reentry (13). The multifactorial origin of electrical remodeling has been extensively studied in cardiac ischemia and heart failure. However, electrical remodeling in hypertension is less well defined. Patients with hypertension-induced left-ventricular hypertrophy are at increased risk for arrhythmias, which contribute to a twofold increase in cardiovascular mortality (7). Monitoring electrical remodeling is challenging. The standard 12-lead electrocardiogram (ECG), ECG-based body surface potential mapping, and signal-averaged ECG are correlated with an increased risk to develop malignant arrhythmias. However, the positive predictive accuracy is unacceptably low or not sufficiently tested in randomized trials (14).Multichannel cardiac magnetic field mapping (CMFM) reflects the magnetic fields generated by the myocardial electrical currents occurring during the cardiac cycle. CMFM signals have several advantages: 1) they are littl...

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“…In humans, multichannel MCG systems provide simultaneous multipoint cardiac mapping, with spatial and temporal resolution adequate to reveal electrophysiological markers for risk of life-threatening arrhythmias (43,44,74). In experimental animal studies, only a few of the 12 ECG leads are usually recorded (9,18,24,47), although high-quality multichannel BSPM in rats has been reported (3,8,49,66,67).…”

Section: Discussionmentioning

confidence: 99%

“…Multichannel MCG mapping measures the magnetic fields (MF) generated by cardiac activation currents, with minimal distortion due to the shape and conductivity of the lungs and torso (20, 28). The advantages of contactless MCG mapping are as follows: 1) the ability to study conscious animals without movement artifacts (65), 2) the potential to provide diagnostic information not revealed by ECG (1,29,36,37,41,43,44,51,54,62,64,69,71,74,75), 3) the fixed-sensors geometry (42), which minimizes errors in localization of intracardiac sources (30) and three-dimensional electroanatomic imaging of arrhythmogenic phenomena (77), and 4) the localization of VR heterogeneities associated with areas of myocardial injury (50).A major problem with MCG mapping of small hearts might be an unfavorable signal-to-noise ratio (S/N), because the cardiac sources are very weak. For this reason, most experimental MCG studies of small animal hearts have been performed in magnetically shielded rooms (4,22,23,65,72).…”

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confidence: 99%

Contactless magnetocardiographic mapping in anesthetized Wistar rats: evidence of age-related changes of cardiac electrical activity

Brisinda¹,

Caristo²,

Fenici³

2006

American Journal of Physiology-Heart and Circulatory Physiology

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Brisinda, Donatella, Maria Emiliana Caristo, and Riccardo Fenici. Contactless magnetocardiographic mapping in anesthetized Wistar rats: evidence of age-related changes of cardiac electrical activity. Am J Physiol Heart Circ Physiol 291: H368 -H378, 2006. First published December 22, 2005 doi:10.1152/ajpheart.01048.2005 is the recording of the magnetic field (MF) generated by cardiac electrophysiological activity. Because it is a contactless method, MCG is ideal for noninvasive cardiac mapping of small experimental animals. The aim of this study was to assess age-related changes of cardiac intervals and ventricular repolarization (VR) maps in intact rats by means of MCG mapping. Twenty-four adult Wistar rats (12 male and 12 female) were studied, under anesthesia, with the same unshielded 36-channel MCG instrumentation used for clinical recordings. Two sets of measurements were obtained from each animal: 1) at 5 mo of age (297.5 Ϯ 21 g body wt) and 2) at 14 mo of age (516.8 Ϯ 180 g body wt). RR and PR intervals, QRS segment, and QTpeak, QTend, JTpeak, JTend, and Tpeak-end were measured from MCG waveforms. MCG imaging was automatically obtained as MF maps and as inverse localization of cardiac sources with equivalent current dipole and effective magnetic dipole models. After 300 s of continuous recording were averaged, the signal-to-noise ratio was adequate for study of atrial and ventricular MF maps and for three-dimensional localization of the underlying cardiac sources. Clear-cut age-related differences in VR duration were demonstrated by significantly longer QT end, JTend, and Tpeak-end in older Wistar rats. Reproducible multisite noninvasive cardiac mapping of anesthetized rats is simpler with MCG methodology than with ECG recording. In addition, MCG mapping provides new information based on quantitative analysis of MF and equivalent sources. In this study, statistically significant age-dependent variations in VR intervals were found. magnetocardiography; cardiac mapping; ventricular repolarization; aging; sex ACCORDING TO RECENT GUIDELINES (7,21,26,27,35,39,48,60,63,65), several ECG indexes, such as QT duration and its dispersion, are used to identify risk of sudden death and assess potential cardiotoxicity of new drugs. The latter requires a large number of animal studies in the preclinical phase of new drug development. For noninvasive assessment of ventricular repolarization (VR) in small experimental animals, the most frequently used method is the 12-lead ECG (24). Extensive body surface potential mapping (BSPM), although more sensitive than the standard ECG for evaluation of repolarization inhomogeneity (2,19,38,57,70), is difficult in small animals, and its use is limited (8, 49).Magnetocardiography (MCG), an easier method for simplification of noninvasive cardiac electrophysiological mapping, can be an appealing alternative to BSPM. Multichannel MCG mapping measures the magnetic fields (MF) generated by cardiac activation currents, with minimal distortion due to the shape and conductivity of the lungs...

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Spatial Distribution of QT Intervals: An Alternative Approach to QT Dispersion

Cited by 38 publications

References 13 publications

Usefulness of Magnetocardiography to Detect Coronary Artery Disease and Cardiac Allograft Vasculopathy

Usefulness of Magnetocardiography to Detect Coronary Artery Disease and Cardiac Allograft Vasculopathy

Angiotensin II-induced sudden arrhythmic death and electrical remodeling

Contactless magnetocardiographic mapping in anesthetized Wistar rats: evidence of age-related changes of cardiac electrical activity

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