Dipole moment of the hearts of various species

Nelson, Clifford V.; Hodgkin, Brian C.; Gastonguay, P. R.

doi:10.1007/bf02390975

Cited by 12 publications

(10 citation statements)

References 14 publications

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“…These results, as well as our preliminary findings with real fMCG measurements, can largely explain an apparent discrepancy between the vector peak-magnitude reported previously by fMCG studies using simplified models (Leeuwen et al 2004, Horigome et al 2001) and the values predicted by studies on vertebrate animals (Nelson et al 1975). …”

Section: Discussioncontrasting

confidence: 66%

The effect of volume conductor modeling on the estimation of cardiac vectors in fetal magnetocardiography

et al. 2012

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Previous studies based on fetal magnetocardiographic (fMCG) recordings used simplified volume conductor models to estimate the fetal cardiac vector as an unequivocal measure of the cardiac source strength. However, the effect of simplified volume conductor modeling on the accuracy of the fMCG inverse solution remains largely unknown. Aiming to determine the sensitivity of the source estimators to the details of the volume conductor model, we performed simulations using fetal-maternal anatomical information from ultrasound images obtained in 20 pregnant women in various stages of pregnancy. The magnetic field produced by a cardiac source model was computed using the boundary element method for a piecewise homogeneous volume conductor with three nested compartments (fetal body, amniotic fluid and maternal abdomen) of different electrical conductivities. For late gestation, we also considered the case of a fourth highly insulating layer of vernix caseosa covering the fetus. The errors introduced for simplified volume conductors were assessed by comparing the reconstruction results obtained with realistic versus spherically symmetric models. Our study demonstrates a significant effect of simplified volume conductor modeling, resulting mainly in an underestimation of the cardiac vector magnitude and low goodness-of-fit. These findings are confirmed by the analysis of real fMCG data recorded in mid-gestation.

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Section: Discussioncontrasting

confidence: 66%

The effect of volume conductor modeling on the estimation of cardiac vectors in fetal magnetocardiography

et al. 2012

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“…The value of the dipole moment was equal to 2.0•10 −5 Am. This was in agreement with the data available elsewhere [33], [38].…”

Section: B Numerical Simulationssupporting

confidence: 94%

“…This assumption was somehow supported by a low interpersonal variation of the equivalent dipole parameters (Table 1). The dipole parameters were determined experimentally from ECG measurements and supported by literature data, [33], [38]. The obtained dipole components were corrected using the method based on transfer impedance approach as proposed by Geselowitz [34].…”

Section: Discussionmentioning

confidence: 99%

QRS Morphology-Based EDR Signal—Factors Determining its Properties

Przystup

Poliński²,

Wtorek³

2022

IEEE Access

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Respiration-induced signals contain a clinically significant information. It could be obtained utilizing both direct and indirect methods. ECG-Derived Respiration (EDR) method is the latter one. However, in this case, two approaches could be distinguished. First one is based on determining changes in the morphology of QRS complexes while the second one is based on the Respiratory Sinus Arrhythmia (RSA) mechanism. The former approach is discussed in the paper. The basic properties of QRS morphology-based EDR signal were evaluated by means of simulations performed using a developed FEM model and appropriate experiments. In effect, basing on changes of the leads' voltages induced by a heart translation or rotation, or by both mechanisms undergoing simultaneously, the sensitivity-like surfaces and the synthetic EDR signals were obtained. A very good agreement of the experimental and simulation results was achieved. The QRS morphology-based signal's properties strongly depend on geometrical relation of the used lead to dominating direction of the heart translation, its rotation, and on personal relation between these two mechanisms. The conclusions presented should be taken into account especially when developing or using QRS morphology-based approach in respiratory monitoring systems.INDEX TERMS Electrocardiography (ECG), ECG-derived respiration (EDR), respiration monitoring.

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“…The relationship between the peak-VM values obtained from fMCG and the estimated fetal weight resembles the one predicted analytically by studies in vertebrate animals (Nelson et al 1975), which indicated a power growth model of the form y = 3.43 · x 0.826 . The exponent parameter of both models are in good agreement, yet the multiplicative constant (scaling factor) estimated in our study is higher ( i.e.…”

Section: Discussionsupporting

confidence: 70%

“…the commonly used linear regression model and a nonlinear power growth model. We tested the power model based on previous observations relating heart dipole moments to heart and body weight in animal studies (Nelson et al 1975). Outliers were automatically identified and excluded in the fitting process using the ROUT method available in the GraphPad Prism (Motulsky and Brown, 2006).…”

Section: Methodsmentioning

confidence: 99%

Cardiac vectors in the healthy human fetus: developmental changes assessed by magnetocardiography and realistic approximations of the volume conductor

et al. 2013

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This study sought to characterize the developmental changes of three measures used to describe the morphology of the fetal cardiac vector: QRS peak-amplitude, QRS duration and QRS time-amplitude integral. To achieve this objective, we rely on a recently developed methodology for fetal cardiac vector estimation, using multichannel fetal magnetocardiographic (fMCG) recordings and realistic approximations of the volume conductors obtained from free-hand ultrasound imaging. Fetal magnetocardiographic recordings and 3D ultrasound images were obtained from 23 healthy, uncomplicated pregnancies for a total of 77 recordings performed at gestational ages between 22 weeks and 37 weeks. We report the developmental changes of the cardiac vector parameters with respect to gestational age and estimated fetal weight, as well as their dependence on the estimated ventricular mass derived from cardiac dimensions measured with M-mode ultrasound. The normative values can be used along with the cardiac time intervals reported by previous fMCG studies to assist future clinical studies investigating conditions that affect fetal cardiac function.

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Dipole moment of the hearts of various species

Cited by 12 publications

References 14 publications

The effect of volume conductor modeling on the estimation of cardiac vectors in fetal magnetocardiography

The effect of volume conductor modeling on the estimation of cardiac vectors in fetal magnetocardiography

QRS Morphology-Based EDR Signal—Factors Determining its Properties

Cardiac vectors in the healthy human fetus: developmental changes assessed by magnetocardiography and realistic approximations of the volume conductor

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