scholarly journals Electrostriction Effects During Defibrillation

2007 ◽  
Vol 6 (2) ◽  
Author(s):  
Michelle Fritz ◽  
Phil Prior ◽  
Bradley Roth
Keyword(s):  
Electric Field ◽  
Cardiac Tissue ◽  
Imaging Techniques ◽  
Stress And Strain ◽  
Mechanical Forces ◽  
Physical Origin ◽  
Anisotropic Cylinder ◽  
Simple Geometry ◽  
Complicated Manner ◽  
A Charge

Background—The electric field applied to the heart during defibrillation causes mechanical forces (electrostriction), and as a result the heart deforms. This paper analyses the physical origin of the deformation, and how significant it is. Methods—We represent the heart as an anisotropic cylinder. This simple geometry allows us to obtain analytical solutions for the potential, current density, charge, stress, and strain. Results—Charge induced on the heart surface in the presence of the electric field results in forces that deform the heart. In addition, the anisotropy of cardiac tissue creates a charge density throughout the tissue volume, leading to body forces. These two forces cause the tissue to deform in a complicated manner, with the anisotropy suppressing radial displacements in favor of tangential ones. Quantitatively, the deformation of the tissue is small, although it may be significant when using some imaging techniques that require the measurement of small displacements. Conclusions—The anisotropy of cardiac tissue produces qualitatively new mechanical behavior during a strong, defibrillation-strength electric shock.

scholarly journals Innovative Biotechnology for Generation of Cardiac Tissue

2021 ◽  
Vol 11 (12) ◽  
pp. 5603
Author(s):  
Greta Ionela Barbulescu ◽  
Florina Maria Bojin ◽  
Valentin Laurentiu Ordodi ◽  
Iacob Daniel Goje ◽  
Taddeus Paul Buica ◽  
...  
Keyword(s):  
Stem Cells ◽  
Electric Field ◽  
Cardiac Tissue ◽  
Sodium Dodecyl ◽  
Human Mesenchymal Stem Cells ◽  
Coronary Perfusion ◽  
Decellularized Extracellular Matrix ◽  
Life Saving ◽  
Cellular Debris ◽  
End Stage

Heart transplantation remains the only curative treatment for end-stage heart failure. This life-saving option continues to be limited by the low number of organ donors, graft rejection and adverse effects of immunosuppressants. Engineering bioartificial hearts from acellular native-derived scaffolds and stem cells has gained attention because of its potential to overcome these limitations. In this study, rat hearts (n = 20) were decellularized by means of coronary perfusion with 1% sodium dodecyl sulfate (SDS) in a modified Langendorff device. The electrical field behavior of the SDS molecule was studied and it was assumed that when applying an alternating current, the exposure time of the tissue to the detergent might decrease. To repopulate the decellularized extracellular matrix (ECM), human mesenchymal stem cells (hMSCs) were used, induced to differentiate into cardiomyocytes (CMs) with 5-azacytidine (5-aza). The results showed no cellular debris and an intact ECM following decellularization. Decellularization in the presence of an electric field proved to be faster, decreasing the potential risk of ECM damage due to the detergent. After cell seeding and culturing of eight scaffolds with hMSCs, the recellularization process was analyzed using optic microscopy (OM), which showed cells suggestive for CMs. This study presents a novel and efficient decellularization protocol using an electric field and suggests that hMSCs can be useful in the generation of a bioartificial heart.

The vibration of electrified water drops

1971 ◽  
Vol 322 (1551) ◽  
pp. 523-534 ◽  
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Axial Ratio ◽  
Uniform Electric Field ◽  
Interferometric Technique ◽  
Photographic Analysis ◽  
Wide Range ◽  
Water Drops ◽  
Strength And Deformation ◽  
A Charge

Pressure has been used as the principal parameter in calculations of the fundamental vibrational frequencies of spherical drops of radius R , density ρ, and surface tension T carrying a charge Q or uncharged spheroidal drops of axial ratio a / b situated in a uniform electric field of strength E . Freely vibrating charged drops have a frequency f = f 0 ( 1 - Q 2 /16π R 3 T ) ½ , as shown previously by Rayleigh (1882) using energy considerations; f 0 is the vibrational frequency of non-electrified drops (Rayleigh 1879). The fundamental frequency of an uncharged drop in an electric field will decrease with increasing field strength and deformation a / b and will equal zero when E ( R )/ T ) ½ = 1.625 and a / b = 1.86; these critical values correspond to the disintegration conditions derived by Taylor (1964). An interferometric technique involving a laser confirmed the accuracy of the calculations concerned with charged drops. The vibration of water drops of radius around 2 mm was studied over a wide range of temperatures as they fell through electric fields either by suspending them in a vertical wind tunnel or allowing them to fall between a pair of vertical electrodes. Photographic analysis of the vibrations revealed good agreement between theory and experiment over the entire range of conditions studied even though the larger drops were not accurately spheroidal and the amplitude of the vibrations was large.

scholarly journals Non-invasive Cardiac Radiation for Ablation of Ventricular Tachycardia: a New Therapeutic Paradigm in Electrophysiology

2018 ◽  
Vol 7 (1) ◽  
pp. 8 ◽  
Author(s):  
Eun-Jeong Kim ◽  
Giovanni Davogustto ◽  
William G Stevenson ◽  
Roy M John ◽  
◽  
...  
Keyword(s):  
Ventricular Tachycardia ◽  
Cardiac Tissue ◽  
Imaging Techniques ◽  
Case Series ◽  
Structural Heart Disease ◽  
Multicenter Studies ◽  
Invasive Approach ◽  
Non Invasive ◽  
Surface Ecg ◽  
Early Case

Non-invasive ablation of cardiac tissue to control ventricular tachycardia (VT) is a novel therapeutic consideration in the management of ventricular arrhythmias associated with structural heart disease. The technique involves the use of stereotactic radiotherapy delivered to VT substrates. Although invasive mapping can be used to identify the target, the use of non-invasive ECG and imaging techniques combined with multi-electrode body-surface ECG recordings offers the potential of a completely non-invasive approach. Early case series have demonstrated a consistent decrease in VT burden and sufficient early safety to allow more detailed multicenter studies. Such studies are currently in progress to further evaluate this promising technology.

Electric Field of a Charge Moving in a Medium

1963 ◽  
Vol 31 (8) ◽  
pp. 601-605 ◽  
Author(s):  
G. M. Volkoff
Keyword(s):  
Electric Field ◽  
A Charge

scholarly journals Radio emission from polar caps in pulsars

1996 ◽  
Vol 160 ◽  
pp. 181-182
Author(s):  
Jan Kuijpers ◽  
Martin Volwerk
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Resonance Condition ◽  
Linear Acceleration ◽  
Stellar Atmospheres ◽  
Double Layers ◽  
Radio Pulsars ◽  
Polar Caps ◽  
Particle Speed ◽  
A Charge

Radiation from a charge accelerated along its path or Linear Acceleration Emission (LAE) involves a number of subtleties (Pauli 1921; Ginzburg 1970, 1989). Potential interest of the mechanism for astrophysics has been pointed out by Wagoner (1969). Melrose (1978) and Rowe (1995) have studied amplified LAE from time-varying electric fields for radio pulsars. In contrast with the latter work our calculations are for static electric field structures or double layers (DLs) as are thought to occur in magnetospheres of neutron stars. In ordinary stellar atmospheres a LAE maser can operate in non-relativistic DLs (Kuijpers 1990) at a frequencyω≈kDLυ≈ 2π/ttr, and a wave vectorwithkDL= 2π/L(Lis the DL length,υis the particle speed, andttris the transit time of the DL by the particle). The emission process can be considered as scattering of the electrostatic electric field on fast electrons into electromagnetic radiation satisfying the resonance condition:, when the frequency of the radiated mode in the frame of the emitting electron equals the Doppler shifted frequency of the electric field of the DL (DL wave frequencyωDL≈ 0). For relativistic DLs, as are applicable to pulsar magnetospheres, the emission is expected to be beamed under an angleθ≈γ−1and the frequency of emission boosted (ω≈kDLυ(1 −υcosθ/c)−1≈γ2kDLυ).

scholarly journals Nematic topological defects positionally controlled by geometry and external fields

2018 ◽  
Vol 9 ◽  
pp. 109-118 ◽  
Author(s):  
Pavlo Kurioz ◽  
Marko Kralj ◽  
Bryce S Murray ◽  
Charles Rosenblatt ◽  
Samo Kralj
Keyword(s):  
Electric Field ◽  
Topological Charge ◽  
Order Parameter ◽  
Topological Defects ◽  
Two Dimensional ◽  
External Fields ◽  
Nematic Ordering ◽  
Spatial Positioning ◽  
A Charge ◽  
The Impact

Using a Landau–de Gennes approach, we study the impact of confinement topology, geometry and external fields on the spatial positioning of nematic topological defects (TDs). In quasi two-dimensional systems we demonstrate that a confinement-enforced total topological charge of m > 1/2 decays into elementary TDs bearing a charge of m = 1/2. These assemble close to the bounding substrate to enable essentially bulk-like uniform nematic ordering in the central part of a system. This effect is reminiscent of the Faraday cavity phenomenon in electrostatics. We observe that in certain confinement geometries, varying the correlation length size of the order parameter could trigger a global rotation of an assembly of TDs. Finally, we show that an external electric field could be used to drag the boojum fingertip towards the interior of the confinement cell. Assemblies of TDs could be exploited as traps for appropriate nanoparticles, opening several opportunities for the development of functional nanodevices.

scholarly journals Mechanostimulation Protocols for Cardiac Tissue Engineering

2013 ◽  
Vol 2013 ◽  
pp. 1-10 ◽  
Author(s):  
Marco Govoni ◽  
Claudio Muscari ◽  
Carlo Guarnieri ◽  
Emanuele Giordano
Keyword(s):  
Gene Expression ◽  
Tissue Engineering ◽  
Regenerative Medicine ◽  
Heart Transplantation ◽  
Biomedical Research ◽  
Cardiac Tissue ◽  
State Of The Art ◽  
Cardiac Tissue Engineering ◽  
Mechanical Forces ◽  
Alternative Strategies

Owing to the inability of self-replacement by a damaged myocardium, alternative strategies to heart transplantation have been explored within the last decades and cardiac tissue engineering/regenerative medicine is among the present challenges in biomedical research. Hopefully, several studies witness the constant extension of the toolbox available to engineer a fully functional, contractile, and robust cardiac tissue using different combinations of cells, template bioscaffolds, and biophysical stimuli obtained by the use of specific bioreactors. Mechanical forces influence the growth and shape of every tissue in our body generating changes in intracellular biochemistry and gene expression. That is why bioreactors play a central role in the task of regenerating a complex tissue such as the myocardium. In the last fifteen years a large number of dynamic culture devices have been developed and many results have been collected. The aim of this brief review is to resume in a single streamlined paper the state of the art in this field.

A Method to Calculate the Electric Field and Ion Current Density at Ground Level for HVDC Transmission Lines during Rain Weather

2013 ◽  
Vol 341-342 ◽  
pp. 1254-1260
Author(s):  
Zhao Zhi Long ◽  
Fei Lu
Keyword(s):  
Flow Field ◽  
Electric Field ◽  
Current Density ◽  
Transmission Lines ◽  
Ground Level ◽  
Ion Current ◽  
Hvdc Transmission ◽  
Hvdc Transmission Lines ◽  
A Charge ◽  
Ion Current Density

HVDC transmission lines can generate an effect on the environment nearby due to the electric field and the ion current density after the corona occurs, so the calculation of ionic flow field is significant to transmission lines design and electromagnetic analysis. However, there is no effective method to calculate the characteristic parameters of ionic flow field under rainy condition. Based on Deutschs assumption, a calculational method is proposed with considering the effects of raindrops on ionic flow field. In the method, the space-charge-free electric field distortion caused by raindrops is especially considered, and the charged raindrops are seen as a charge background of transmission lines. The field strengths and ion current densities calculated using this method are compared with the experimental results in the published literature, it shows that the method is effective and accurate enough under fair and rainy conditions.

Sign in / Sign up

Export Citation Format

Share Document