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Ramirez E.,Technological Institute of Cuautla | Saiz J.,Polytechnic University of Valencia | Romero L.,Polytechnic University of Valencia | Ferrero J.M.,Polytechnic University of Valencia | Trenor B.,Polytechnic University of Valencia

Aims: This computational modelling work illustrates the influence of hyperkalaemia and electrical uncoupling induced by defined ischaemia on action potential (AP) propagation and the incidence of reentry at the Purkinje-ventricle interface in mammalian hearts. Methods and results: Unidimensional and bidimensional models of the Purkinje-ventricle subsystem, including ischaemic conditions (defined as phase 1B) in the ventricle and an ischaemic border zone, were developed by altering several important electrophysiological parameters of the Luo-Rudy AP model of the ventricular myocyte. Purkinje electrical activity was modelled using the equations of DiFrancesco and Noble. Our study suggests that an extracellular potassium concentration [K+]o >14 mM and a slight decrease in intercellular coupling induced by ischaemia in ventricle can cause conduction block from Purkinje to ventricle. Under these conditions, propagation from ventricle to Purkinje is possible. Thus, unidirectional block (UDB) and reentry can result. When conditions of UDB are met, retrograde propagation with a long delay (320 ms) may re-excite Purkinje cells, and give rise to a reentrant pathway. This induced reentry may be the origin of arrhythmias observed in phase 1B ischaemia. Conclusion: In a defined setting of ischaemia (phase 1B), a small amount of uncoupling between ventricular cells, as well as between Purkinje and ventricular tissue, may induce UDBs and reentry. Hyperkalaemia is also confirmed to be an important factor in the genesis of reentrant rhythms, since it regulates the range of coupling in which UDBs may be induced. © The Author 2014. Source

Gonzalez-Gaxiola O.,Metropolitan Autonomous University | Bulnes F.,Technological Institute of Cuautla
Advanced Studies in Theoretical Physics

In this work is introduced the harmonic oscillator process that in probability is known as Ornstein-Uhlenbeck process or velocities process of Ornstein-Uhlenbeck and is established that the mathematical expectation of certain functionals of this process coincides with the expected value of certain observables in the fundamental state or basis state to the oscillator and with it is found a relation between the spaces of classical and quantum probability. Furthermore is established a certain algebra of operators that gives rise to the dynamics of quantum harmonic oscillator and to consider certain class of perturbations of the Hamiltonian corresponding to their harmonic oscillator is obtained a version of the Feynman-Kac formula with a dilatation generated by the unitary group of translations for a co-cycle. Finally are given some generalizations of the Feynman-Kac formula. © 2013 O. González-Gaxiola and Francisco Bulnes. Source

Ramirez E.,Technological Institute of Cuautla | Ramirez E.,Polytechnic University of Valencia | Saiz J.,Polytechnic University of Valencia | Trenor B.,Polytechnic University of Valencia
Computing in Cardiology

Arrhythmias induced by phase 1B of ischemia are poorly understood. A bidimensional computer model has been developed to study the interaction between a bundle of Purkinje fibers and a layer of ventricular ischemic tissue. The present work has focussed on the role of the increase of extracellular potassium concentration and changes in the cellular coupling provoked by 1B ischemia in ventricular tissue connected to Purkinje fibers. To simulate 1B ischemic conditions, we altered several electro-physiological parameters of the Luo-Rudy action potential model(Lrd00). Our study suggests that a greater extracellular potassium concentration than 14.2 mmol/L and the moderate increase of cellular uncoupling induced by ischemia in a ventricular zone could cause conduction block in Purkinje to ventricle and conduction in ventricle to Purkinje, thus generating unidirectional block and reentry. © 2012 CCAL. Source

Polanco-Martagon S.,CENIDET | Reyes-Salgado G.,CENIDET | Reyes-Salgado G.,Technological Institute of Cuautla | Flores-Becerra G.,Puebla Institute of Technology | And 4 more authors.
Journal of Applied Research and Technology

A fuzzy sets intersection procedure to select the optimum sizes of analog circuits composed of metal-oxidesemiconductor field-effect-transistors (MOSFETs), is presented. The cases of study are voltage followers (VFs) and a current-feedback operational amplifier (CFOA), where the width (W) and length (L) of the MOSFETs are selected from the space of feasible solutions computed by swarm or evolutionary algorithms. The evaluation of three objectives, namely: gain, bandwidth and power consumption; is performed using HSPICETM with standard integrated circuit (IC) technology of 0.35μm for the VFs and 180nm for the CFOA. Therefore, the intersection procedure among three fuzzy sets representing "gain close to unity", "high bandwidth" and "minimum power consumption", is presented. The main advantage relies on its usefulness to select feasible W/L sizes automatically but by considering deviation percentages from the desired target specifications. Basically, assigning a threshold to each fuzzy set does it. As a result, the proposed approach selects the best feasible sizes solutions to guarantee and to enhance the performances of the ICs in analog signal processing applications. Source

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