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In order to evaluate the effects of electromagnetic fields (EMF) of ultra high voltage (UHV) transmission lines exposure on important life organs and tissues of BALB/c mice, an exposed environment was constructed in laboratory. Fifty male adult BALB/c mice were divided into two groups. One group has been done by daily exposures of 24 hours, and the other sham-exposed group served as the control. After...
Slow conduction through the Purkinje-ventricular junction (PVJ) is thought to result in conduction block and ultimately re-entry under certain pathological conditions. The relationships between tissue structure, conduction velocity and the safety of conduction at such junctions however, are unknown. We developed an electrophysiologically detailed 3D model of the PVJ and varied the Purkinje fibre thickness...
Mechanical contraction alternans of the heart is associated with fatal cardiac death. It is manifested by T-wave alternans in the ECG, and is thought to be possibly related to intracellular Ca2+ transient alternans released from the sarcoplasmic reticulum (SR). However, it is unclear yet how beat-to-beat alternans of intracellular Ca2+ transient is produced. In this study investigated the mechanism(s)...
We postulated that atrial fibrillation (AF) induced electrical remodelling in electrically heterogeneous human atria facilitates chronic AF. A modern biophysically detailed mathematical model of human atrial action potential was modified to incorporate electrophysiological properties of different cell types present within the atria. The heterogeneous cell models were then further modified to incorporate...
Purkinje fiber (PF) cells exhibit action potential (AP) morphology and duration markedly different to those of ventricle myocytes. In order to study heterogeneity at the Purkinje-ventricular junction (PVJ), we construct a new AP model for the canine PF cell based on detailed experimental data of ion channel characteristics obtained by voltage clamp techniques. Single-cell PF model is incorporated...
The idea of this research is to determine how long in advance can we predict the onset of paroxysmal atrial fibrillation (PAF) from the HRV data. Having established such methods with great confidence it is possible to avert the PAF onset using pacing techniques, thus reliving patient pains.
Idiopathic short QT (SQT) syndrome is a recently identified, genetically heterogeneous condition characterized by abbreviated QT intervals and an increased susceptibility to arrhythmia and sudden death. In this computer simulation study, we identify the mechanisms by which cellular electrophysiological changes in the SQT syndrome associated with V307L KvLQT1 (KCNQ1) gene mutation (the gene coding...
Remarkable differences in action potential properties between the Purkinje fibre and ventricular cells may lead to abnormalities in excitation conduction through the Purkinje-ventricular junction (PVJ) and arrhythmogenic behaviour. We develop a family of electrophysiologically detailed computer models for rabbit epicardial, midmyocardial and endocardial ventricular myocytes, as well as the rabbit...
We computationally evaluated the functional roles of atrial fibrillation induced electrical remodelling (AFER) on human atrial electrical excitations at cellular, tissue and whole organ levels. Our results show that AFER produced a dramatic reduction in action potential duration, slowing down of intra-atrial conduction, decrease in tissuepsilas temporal vulnerability, but remarkable increase in tissuepsilas...
In both human and animal mammals, the pacemaker of the heart, the sinoatrial node (SA node), deteriorates with age. The main features of the aged SA nodes are a slow pacemaking rate and possible SA node-atrium conduction exit block or arrest of SA node pacemaking (i.e., termination of the SA node pacemaker activity). The mechanisms underlying the age-related dysfunction of the heart are unclear. In...
We have developed a three-dimensional computational wedge model of canine cardiac ventricular wall electro-physiology that incorporates biophysically detailed, spatially heterogeneous excitation, and high-resolution geometry and fibre orientation. Isolated cell model electrophysiological characteristics reproduce the experimentally observed characteristics under control conditions, and under conditions...
Down-regulation of Kir2.1 channel reduces the inward-rectifier potassium current (iK1), and transforms excitable ventricular myocytes to pacemaker cells. This provides a possible bio-technique to induce a biological pacemaker, as an alternative to an implantable electronic pacemaker. However there are two fundamental issues: (i) the stability of the pacemaker activity; (ii) the critical size of the...
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