Study of Electric and Mechanic Properties of the Implanted Artificial Cardiac Tissue Using a Whole Heart Model (original) (raw)

Computer simulations of successful defibrillation in decoupled and non-uniform cardiac tissue

Europace, 2005

Aim The aim of the present study is to investigate the origin and effect of virtual electrode polarization in uniform, decoupled and non-uniform cardiac tissue during field stimulation. Methods A discrete bidomain model with active membrane behaviour was used to simulate normal cardiac tissue as well as cardiac tissue that is decoupled due to fibrosis and gap junction remodelling. Various uniform and non-uniform electric fields were applied to the external domain of uniform, decoupled and non-uniform resting cardiac tissue as well as cardiac tissue in which spiral waves were induced. Results Field stimulation applied on non-uniform tissue results in more virtual electrodes compared with uniform tissue. The spiral waves were terminated in decoupled tissue, but not in uniform, homogeneous tissue. By gradually increasing local differences in intracellular conductivities, the amount and spread of virtual electrodes increased and the spiral waves were terminated. Conclusion Fast depolari...

The Electrical Activity of Cardiac Tissue via Finite Element Method

For the treatment of certain cardiac disorders sometimes electrical currents are used as therapy, as it happens when fibrillation. This phe-nomenon manifest itself with chaotic and accelerated heart rhythm, pre-venting the pumping of blood to the rest the organism. In considering this type of heart disease, introduce mathematical models to analyze the dynamics and behavior of these discharges, in particular, bidomain model is one of the most studied in order to understand the electrical process in cardiac tissue as a phenomenon that can be mathematically modeled .

Electrical Propagation in Distributed Cardiac Tissue

Theory of Heart: Biomechanics, Biophysics, and Nonlinear Dynamics of Cardiac Function, ed. by L. Glass, P. Hunter, and A. McCulloch, 1991

Basic properties concerning electrical propagation in cardiac tissue are discussed. Electrical properties in passive and excitable tissue are described in the one-dimensional case. Realistic mathematical models in higher dimensions will have to take into account discreteness caused by finite conductance of cell couplings, anisotropy of cardiac muscle, and the finite resistance of the extracellular conductance.

An electromechanical model for cardiac tissue constructs

The presented work computationally investigates cardiac tissue constructs, so-called engineered heart tissues, that consist of a collagen-based extracellular matrix and human-induced pluripotent stem-cell derived cardiomyocytes. A finite element model is built in order to support the interpretation of experimental results and to predict for instance the effect of drug application to the tissue. The electro-mechanically coupled model proves to be useful by means of elucidating macroscopic experimental results at the microscopic level.

Control of cardiac alternans in an electromechanical model of cardiac tissue

Computers in Biology and Medicine, 2015

Electrical alternations in cardiac action potential duration have been shown to be a precursor to arrhythmias and sudden cardiac death. Through the mechanism of excitation-contraction coupling, the presence of electrical alternans induces alternations in the heart muscle contractile activity. Also, contraction of cardiac tissue affects the process of cardiac electric wave propagation through the mechanism of the so-called mechanoelectrical feedback. Electrical excitation and contraction of cardiac tissue can be linked by an electromechanical model such as the Nash-Panfilov model. In this work, we explore the feasibility of suppressing cardiac alternans in the Nash-Panfilov model which is employed for small and large deformations. Several electrical pacing and mechanical perturbation feedback strategies are considered to demonstrate successful suppression of alternans on a one-dimensional cable. This is the first attempt to combine electrophysiologically relevant cardiac models of electrical wave propagation and contractility of cardiac tissue in a synergistic effort to suppress cardiac alternans. Numerical examples are provided to illustrate the feasibility and the effects of the proposed algorithms to suppress cardiac alternans.

A finite Element Model for the Electrical Activity in Human Cardiac Tissues

Biosimulation models of the heart action potential have become a very useful tool. It provides better understanding for the complex biophysical phenomena related to electrical activity in the heart such as cardiac arrhythmias. At cellular level, the electrical activity of cardiac tissues may be simulated by solving a system of ordinary deferential equations (ODEs) describing the electrical behavior of the cell membrane. Because the biophysical processes underlying this phenomenon are non-linear and change very rapidly, the ODE system is a challenge to be solved numerically. Furthermore, the implementation of these models is a hard task for commercial finite element software. In this paper a finite element formulation, model and code generation of monodomain equation has been conducted. The developed code is coupled with the modified FitzHugh-Nagumo (FHN) cell electrophysiological model in order to have isotropic excitation propagation starting from cell level to complete heart level. MTALAB programming language was used to build the proposed standalone finite element code. A two dimensional specimen of heart tissues is simulated to show the behavior of the excitation propagation and the repolarization phase for isotropic electrical activity. Simulation results of the cardiac action potential have shown good agreements with the experimental measurements obtained from published literature.

Cardiac muscle tissue engineering: toward an in vitro model for electrophysiological studies

American Journal of Physiology-Heart and Circulatory Physiology, 1999

The objective of this study was to establish a three-dimensional (3-D) in vitro model system of cardiac muscle for electrophysiological studies. Primary neonatal rat ventricular cells containing lower or higher fractions of cardiac myocytes were cultured on polymeric scaffolds in bioreactors to form regular or enriched cardiac muscle constructs, respectively. After 1 wk, all constructs contained a peripheral tissue-like region (50–70 μm thick) in which differentiated cardiac myocytes were organized in multiple layers in a 3-D configuration. Indexes of cell size (protein/DNA) and metabolic activity (tetrazolium conversion/DNA) were similar for constructs and neonatal rat ventricles. Electrophysiological studies conducted using a linear array of extracellular electrodes showed that the peripheral region of constructs exhibited relatively homogeneous electrical properties and sustained macroscopically continuous impulse propagation on a centimeter-size scale. Electrophysiological prope...

Activation Propagation in Cardiac Ventricles Using the Model with the Conducting System

IFMBE Proceedings, 2018

The characteristics of the activation propagation in a geometrical model of cardiac ventricles formed by several ellipsoids, with or without a fast conducting endocardial layer representing the Purkinje fibers and with activation started in one or several endocardial locations were compared in this study. The activation propagation was simulated by two approaches. In the first one, temporal and spatial changes of the membrane potential were numerically modeled by a reaction-diffusion (RD) equation of the propagation with the transmembrane ionic current density defined by modified FitzHugh-Nagumo equations. The propagation was numerically solved in Comsol Multiphysics environment. In the second approach, the electrical excitation of the working ventricular myocardium was simulated by a cellular automaton (CA) model that was implemented in Matlab environment. Local activation times in both ventricles were computed by both approaches in ventricular models with and without the fast conducting layer representing Purkinje fibers (heterogeneous and homogeneous model). In both models, the activation was initiated either in a single starting position or gradually in nine starting positions imitating more physiological conditions. Despite some differences in the activation sequences, by both approaches acceptable activation times of the whole ventricles were obtained for the homogeneous model with nine starting points and for the model with conducting layer regardless of number of starting positions.

A synthetic strand of cardiac muscle: its passive electrical properties

The Journal of General Physiology, 1975

The passive electrical properties of synthetic strands of cardiac muscle, grown in tissue culture, were studied using two intracellular microelectrodes: one to inject a rectangular pulse of current and the other to record the resultant displacement of membrane potential at various distances from the current source. In all preparations, the potential displacement, instead of approaching a steady value as would be expected for a cell with constant electrical properties, increased slowly with time throughout the current step. In such circumstances, the specific electrical constants for the membrane and cytoplasm must not be obtained by applying the usual methods, which are based on the analytical solution of the partial differential equation describing a one-dimensional cell with constant electrical properties. A satisfactory fit of the potential waveforms was, however, obtained with numerical solutions of a modified form of this equation in which the membrane resistance increased line...