In the chronic stage of myocardial infarction, a significant number patients develop life-threatening ventricular tachycardias (VT) due to arrhythmogenic nature remodeled myocardium. Radiofrequency ablation (RFA) is common procedure isolate reentry pathways across infarct scar that are responsible for VT. Unfortunately, this strategy show relatively low success rates; up 50% experience recurrent VT after procedure. last decade, intensive research in field computational cardiac...

The role of the ATP-sensitive K + current (I K-ATP ) and its contribution to electrophysiological changes that occur during metabolic impairment in cardiac ventricular myocytes is still being discussed. aim this work was quantitatively study issue by using computer modeling. A model I formulated incorporated into Luo-Rudy ionic action potential. Action potentials under different degrees activation are simulated. Our results show normal concentrations, only ≈0.6% ATP channels, when open,...

Heart failure constitutes a major public health problem worldwide. The electrophysiological remodeling of failing hearts sets the stage for malignant arrhythmias, in which role late Na+ current (INaL) is relevant and currently under investigation. In this study we examined INaL phenotype ventricular myocytes, its proarrhythmic effects heart. A model cellular heart was proposed using modified version Grandi et al. human action potential that incorporates formulation INaL. sensitivity analysis...

Background Heart failure is a final common pathway or descriptor for various cardiac pathologies. It associated with sudden death, which frequently caused by ventricular arrhythmias. Electrophysiological remodeling, intercellular uncoupling, fibrosis and autonomic imbalance have been identified as major arrhythmogenic factors in heart etiology progression. Objective In this study we investigate silico the role of electrophysiological structural remodeling on modulation key elements...

Acute myocardial ischemia induces hyperkalemia (accumulation of extracellular potassium), a major perpetrator lethal reentrant ventricular arrhythmias. Despite considerable experimental efforts to explain this pathology in the last decades, intimate mechanisms behind remain partially unknown. In order investigate these mechanisms, we developed novel computational model acute which couples a) an electrophysiologically detailed human cardiomyocyte that incorporates modifications account for...

The goal of this modeling research is to provide mechanistic insight into the effect altered membrane kinetics associated with 5-12 min acute global ischemia on upper limit cardiac vulnerability (ULV) electric shocks. We simulate electrical activity in a finite-element bidomain model 4-mm-thick slice through canine ventricles that incorporates realistic geometry and fiber architecture. Global represented by changes dynamics due hyperkalemia, acidosis, hypoxia. Two stages are simulated...

Ischaemic heart disease is considered as the single most frequent cause of death, provoking more than 7 000 deaths every year worldwide. A high percentage patients experience sudden cardiac caused in cases by tachyarrhythmic mechanisms associated to myocardial ischaemia and infarction. These diseases are difficult study using solely experimental means due their complex dynamics unstable nature. In past decades, integrative computational simulation techniques have become a powerful tool...

Abnormal intracellular Ca2+ handling is the major contributor to depressed cardiac contractility observed in heart failure. The electrophysiological remodeling associated with this pathology alters both action potential and dynamics, leading a defective excitation-contraction coupling that ends mechanical dysfunction. importance of maintaining correct concentration requires better understanding its regulation by ionic mechanisms. To study electrical activity homeostasis failing myocytes,...

In this work, the authors use computer modeling to theoretically investigate mechanisms involved in figure-of-eight reentry during acute regional myocardial ischemia, a pattern of excitation which may lead ventricular fibrillation and sudden cardiac death. For purpose, modified version Luo–Rudy dynamic model for action potential ionic currents has been used, together with two-dimensional regionally ischemic ventricle. The virtual tissue comprises several realistically dimensioned located...

The contribution of the transient outward potassium current (I(to)) to ventricular repolarization is controversial as it depends on experimental conditions, region myocardium and species studied. aim present study was therefore characterize I(to) estimate its reserve in canine myocardium.Ion currents were recorded using conventional whole-cell voltage clamp action potential techniques isolated cells. Action potentials from preparations microelectrodes. studied 100 µM chromanol 293B presence...

Patients suffering from heart failure and left bundle branch block show electrical ventricular dyssynchrony causing an abnormal blood pumping. Cardiac resynchronization therapy (CRT) is recommended for these patients. with positive response normally present QRS shortening increased ventricle (LV) ejection fraction. However, around one third do not respond favorably. Therefore, optimal location of pacing leads, timing delays between leads and/or choosing related biomarkers crucial to achieve...

In this study, we have used computer simulations to study the mechanisms of extracellular K + accumulation during acute ischemia. A modified version Luo-Rudy phase II action potential model was simulate electrical behavior one ventricular myocyte 14 min simulated Our results show following: 1) only integrated effect activation ATP-dependent current, an ischemic Na inward and inhibition -K pump activity in absence coronary flow replicates biphasic time course concentration observed ischemia;...

The use of antiarrhythmic drugs is common to treat heart rhythm disorders. Computational modeling and simulation are promising tools that could be used investigate the effects specific on cardiac electrophysiology. In this paper, we study multiscale dofetilide, a drug blocks IKr, from cellular organ level paying special attention its effect structures, in particular specialized conduction system (CCS). We include model CCS patient-specific anatomical ventricular simulations with without CCS....

Computer modeling is used to study the effect of electrical coupling between a myocardial zone where early after-depolarizations (EADs) can develop and normal neighboring tissue. The effects such on EAD development likelihood propagation as an ectopic beat are studied. influence formation investigated by approximating two partially coupled zones modeled active elements junctional resistance R. For R values lower than 800 /spl Omega/ cm/sup 2/, action potentials transmitted element, for...

The powerline interference reduction in ECG records is a challenging problem which still open for research. signal, measured directly from the transmission line may have amplitude, phase and frequency variations. These reasons make classical filtering methods sub-optimal reduction. We propose tracking method based on Kalman uses an state space model noisy signal allows adequate discrimination between perturbation, even during non-stationarities. parameters of this algorithm are optimized via...

Dofetilide is a class-III drug that inhibits the rapid component of delayed potassium current ( I(Kr)). Experimental studies have shown different layers ventricular muscle present differences in action potential duration (APD) and responses to class III agents. It has been suggested it contributes APD heterogeneity ventricles. However, vivo suggest strong cellular coupling reduces dispersion intact heart. The aim this paper study effect dofetilide on potentials (APs) isolated cells strand...

Heart failure (HF) is characterized by altered Ca2+ cycling, resulting in cardiac contractile dysfunction. Failing myocytes undergo electrophysiological remodeling, which known to be the main cause of abnormal homeostasis. However, structural specifically proliferating fibroblasts coupled failing heart, could also contribute cycling impairment. The goal present study was systematically analyze mechanisms myocyte-fibroblast coupling affect dynamics normal conditions and HF. Simulations...