Sparse Representation for Cardiac Electrical Activity Imaging in Magnetocardiography

2021 ◽  
Vol 11 (7) ◽  
pp. 2025-2032
Author(s):  
Lu Bing ◽  
Wei Wang
Keyword(s):  
Magnetic Field ◽  
Electrical Activity ◽  
Current Source ◽  
Optimization Methods ◽  
Sparse Constraint ◽  
Non Invasive ◽  
Cardiac Electrical Activity ◽  
Underdetermined System ◽  
Spatial Changes ◽  
Temporal And Spatial

Signal sparsity has been widely discussed in communication system, cloud computing, multimedia processing and computational biology. Reconstructing the sparsely distributed current sources of the heart by means of non-invasive magnetocardiography (MCG) measurement and various optimization methods provides a new way to solve the inverse problem of the cardiac magnetic field. The problem of sparse source location of MCG is in the time series of MCG measurement caused by active sparse current source, can the spatiotemporal source be reconstructed accurately and effectively? For the above problem, the scientific contributions of the paper include: (1) A modified focal underdetermined system solver algorithm is proposed for a sparse solution, by combing with dynamic regularization factor and smoothed sparse constraint; (2) Lead field matrix is reduced by prior information of cardiac magnetic field map to reduce under-determination; (3) Spatiotemporal sources are reconstructed for non-invasive cardiac electrical activity imaging. The results of real MCG data demonstrate the effectiveness of this method for cardiac electrical activity imaging. The temporal and spatial changes of the current sources are similar to the depolarization and repolarization process of the ventricle.

scholarly journals Current source reconstructing and magnetic imaging of cardiac electrical activity during P-wave

2019 ◽  
Vol 68 (13) ◽  
pp. 138701
Author(s):  
Da-Fang Zhou ◽  
Shi-Qin Jiang ◽  
Chen Zhao ◽  
van Leeuwen Peter
Keyword(s):  
Electrical Activity ◽  
Current Source ◽  
P Wave ◽  
Magnetic Imaging ◽  
Cardiac Electrical Activity

Expression of oncofetal fibronectin in porcine conceptuses and uterus throughout gestation

1996 ◽  
Vol 8 (8) ◽  
pp. 1207 ◽  
Author(s):  
W Tuo ◽  
FW Bazer
Keyword(s):  
Monoclonal Antibody ◽  
Animal Model ◽  
Epithelial Cells ◽  
Mammalian Species ◽  
Normal Pregnancy ◽  
Non Invasive ◽  
Spatial Changes ◽  
Porcine Conceptus ◽  
Oncofetal Fibronectin ◽  
Temporal And Spatial

Oncofetal fibronectin is reportedly expressed specifically by trophoblast tissue and some tumours and speculated to mediate placental attachment. In the present study, a monoclonal antibody (FDC-6) to human oncofetal fibronectin was used to characterize temporal and spatial changes in the expression of oncofetal fibronectin at the fetal-maternal interface of pigs. Conceptus and uterine tissues were collected from gilts throughout normal pregnancy and processed for immunohistochemical characterization. Results indicated that oncofetal fibronectin was constitutively expressed by both porcine conceptus and uterus throughout gestation. The most abundant staining for oncofetal fibronectin was found in the allantochorion and detectable levels of oncofetal fibronectin were also detected in luminal and glandular epithelial cells in the uterus. During the second-half of pregnancy, oncofetal fibronectin was also detected in fibroblast-like cells in the uterine stroma, but not in the stroma of the allantochorion. Owing to the non-invasive nature of the porcine placenta, the abundant expression of oncofetal fibronectin by the trophoblast and uterus may influence attachment between chorion and endometrium during pregnancy. Since attachment is the first step in implantation and placentation in all mammalian species, the pig may represent an excellent animal model to study interactions between trophoblast and endometrium mediated by oncofetal fibronectin.

scholarly journals Simulations of magnetocardiographic signals using realistic geometry models of the heart and torso

2012 ◽  
Vol 10 ◽  
pp. 85-91
Author(s):  
C. V. Motrescu ◽  
L. Klinkenbusch
Keyword(s):  
Magnetic Field ◽  
Electrical Activity ◽  
Diagnostic Technique ◽  
Reaction Diffusion ◽  
Ionic Currents ◽  
Diffusion Problem ◽  
Reaction Diffusion Equation ◽  
Volume Conduction ◽  
Cardiac Electrical Activity ◽  
Current Densities

Abstract. Although the first measurement of the cardiac magnetic field was reported almost half a century ago magnetocardiography (MCG) is not yet widely used as a clinical diagnostic technique. With the development of a new generation of magnetoelectric sensors it is believed that MCG will become widely accepted in the clinical diagnosis. Our goal is to build a computer-based tool for medical diagnosis and to use it for the clarification of open electro-physiological questions. Here we present results from modelling of the cardiac electrical activity and computation of the generated magnetic field. For the simulations we use MRT-based anatomical models of the human atria and ventricles where the shape of the action potential is determined by ionic currents passing through the cardiac cell membranes. The monodomain reaction-diffusion equation is chosen for the description of the heart's electrical activity. This equation is solved for the transmembrane voltage which is in turn used to calculate current densities at discrete time instants. In subsequent simulations these current densities represent primary sources of magnetostatic fields arising from a volume conduction problem. In these simulations the heart is placed in a realistic torso model where the lungs are also considered. Both, the volume conduction problem as well as the reaction-diffusion problem are modelled using Finite-Element techniques.

Fate of sperm membrane in fertilized ova

1993 ◽  
Vol 51 ◽  
pp. 40-41
Author(s):  
Frank J. Longo
Keyword(s):  
Electron Microscopy ◽  
Electrical Activity ◽  
Sea Urchins ◽  
Morphological Changes ◽  
Integrated System ◽  
Electrophysiological Recording ◽  
Experimental Conditions ◽  
The Status ◽  
Sperm Membrane ◽  
Temporal And Spatial

Measurement of the egg's electrical activity, the fertilization potential or the activation current (in voltage clamped eggs), provides a means of detecting the earliest perceivable response of the egg to the fertilizing sperm. By using the electrical physiological record as a “real time” indicator of the instant of electrical continuity between the gametes, eggs can be inseminated with sperm at lower, more physiological densities, thereby assuring that only one sperm interacts with the egg. Integrating techniques of intracellular electrophysiological recording, video-imaging, and electron microscopy, we are able to identify the fertilizing sperm precisely and correlate the status of gamete organelles with the first indication (fertilization potential/activation current) of the egg's response to the attached sperm. Hence, this integrated system provides improved temporal and spatial resolution of morphological changes at the site of gamete interaction, under a variety of experimental conditions. Using these integrated techniques, we have investigated when sperm-egg plasma membrane fusion occurs in sea urchins with respect to the onset of the egg's change in electrical activity.

The Role of Computer Modeling in Electrocardiography

1990 ◽  
Vol 29 (04) ◽  
pp. 282-288 ◽  
Author(s):  
A. van Oosterom
Keyword(s):  
Electrical Activity ◽  
Computer Modeling ◽  
Body Surface ◽  
Electrical Current ◽  
The Body ◽  
Volume Conductor ◽  
Current Generator ◽  
Cardiac Electrical Activity ◽  
Source Models

AbstractThis paper introduces some levels at which the computer has been incorporated in the research into the basis of electrocardiography. The emphasis lies on the modeling of the heart as an electrical current generator and of the properties of the body as a volume conductor, both playing a major role in the shaping of the electrocardiographic waveforms recorded at the body surface. It is claimed that the Forward-Problem of electrocardiography is no longer a problem. Several source models of cardiac electrical activity are considered, one of which can be directly interpreted in terms of the underlying electrophysiology (the depolarization sequence of the ventricles). The importance of using tailored rather than textbook geometry in inverse procedures is stressed.

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