Magnetocardiographic and Electrocardiographic Mapping Studies

Stroink, G.; Lamothe, Marcel; Gardner, Martin J.

doi:10.1007/978-94-011-5674-5_10

Cited by 8 publications

(4 citation statements)

References 57 publications

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“…However, the ionic current in a single neuron is of the order of picoamperes and results in a magnetic field strength of the order of 10 Ϫ15 T (16). For comparison, the field strength from lung particles is Ϸ10 Ϫ9 T, from magnetocardiogram is Ϸ10 Ϫ10 T, from the brain 10 Ϫ12 T for spontaneous (␣ wave) activity, and 10 Ϫ13 T for evoked response (17,18). These magnetic field changes are far beyond MRI detection capabilities.…”

Section: Discussionmentioning

confidence: 98%

Current-Induced Magnetic Resonance Phase Imaging

Bodurka

Jeśmanowicz

Hyde

et al. 1999

Journal of Magnetic Resonance

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Section: Discussionmentioning

confidence: 98%

Current-Induced Magnetic Resonance Phase Imaging

Bodurka

Jeśmanowicz

Hyde

et al. 1999

Journal of Magnetic Resonance

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“…Since the early 1970s, MCG has been proposed as the magnetic alternative to ECG and BSPM for the noninvasive study of cardiac electrophysiology (1,20,28,51,62,69,75). 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).…”

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).…”

mentioning

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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“…Magnetic field mapping (MFM), a non-invasive method used to measure the magnetic field outside the thorax caused by electric currents in the body, and body surface potential mapping (BSPM), a method used to measure the electrical potential with the help of electrodes on the skin, are two promising techniques for electrophysiological imaging of heart activity (Weismüller et al 1993, Moshage et al 1996, Fenici and Melillo 1993, Oeff and Burghoff 1994, Stroink et al 1996, van Oosterom et al 1997, Mäkijärvi et al 1992, Rudy and Taccardi 1998, MacLeod et al 1995. For example, the assessment of myocardial viability in coronary artery disease or the understanding of arrhythmogenesis in malignant ventricular tachyarrythmias may profit from these non-invasive, electrophysiological imaging techniques.…”

Section: Introductionmentioning

confidence: 99%

Source localization in an inhomogeneous physical thorax phantom

et al. 1999

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The influence of lung inhomogeneities on focal source localizations in electrocardiography (ECG) and magnetocardiography (MCG) is investigated. A realistically shaped physical thorax phantom with cylindrical lung inhomogeneities is used for electric and magnetic measurements. The lungs are modelled with a special ionic exchange membrane which allows different conductivity compartments without influencing the free ionic current flow. The dipolar current sources are composed of platinum wire and located at different depths and directions between the lung inhomogeneities. We localized the current dipoles with different boundary element method (BEM) models, based on electrical data and simultaneous electrical and magnetic data. Our results indicate the possibility of superadditive information gain by combining electrical and magnetic data for source reconstructions. We found a significant influence of the inhomogeneities on both the calculated source location and the calculated source strength. Mislocalizations of up to 16 mm and wrong dipole strengths of up to 52% were obtained when the lung inhomogeneities were not taken into account for source localization. Dipoles parallel to the lungs showed a larger localization error in depth than dipoles perpendicular to the lungs. We conclude that the incorporation of lung inhomogeneities will improve source localization accuracy in ECG and MCG.

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Magnetocardiographic and Electrocardiographic Mapping Studies

Cited by 8 publications

References 57 publications

Current-Induced Magnetic Resonance Phase Imaging

Current-Induced Magnetic Resonance Phase Imaging

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

Source localization in an inhomogeneous physical thorax phantom

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