Article
A model of the ventricular cardiac action potential. Depolarization, repolarization, and their interaction.
Department of Biomedical Engineering, Case Western Reserve University, Cleveland, Ohio 44106.
Circulation Research (Impact Factor: 11.09). 07/1991; 68(6):150126. Source: PubMed

Conference Paper: Luo Rudy Phase I excitation modeling towards HDL coder implementation for realtime simulation
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ABSTRACT: This paper presents the simulation study of nonlinear dynamic of cardiac excitation based on Luo Rudy Phase I (LRI) model towards numerical solutions of ordinary differential equations (ODEs) responsible for cardiac excitation on field programmable gate arrays (FPGAs). As computational modeling needs vast of simulation time, a realtime hardware implementation using FPGA could be the solution as it provides high configurability and performance. For rapid prototyping, MATLAB Simulink that offers a link with the FPGA has been used. Through Simulink HDL Coder, a tool in the MATLAB software that capable to convert the MATLAB Simulink blocks into hardware description language (HDL) code and an FPGAintheloop (FIL) and cosimulation for verification, FPGA hardware implementation can be done. As a result, the LRI excitation model is successfully simulated by using the MATLAB Simulink and the VHDL code has been successfully generated by the HDL Coder after fixedpoint optimization is done. The FIL verification on actual FPGA board also has shown quantitatively comparable results to the MATLAB Simulink simulation. Therefore, the design flow has given a positive outlook in developing this FPGA standalone implementation.2014 5th International Conference on Intelligent and Advanced Systems (ICIAS); 06/2014  [Show abstract] [Hide abstract]
ABSTRACT: During haemodialysis (HD) sessions, patients undergo alterations in the extracellular environment, mostly concerning plasma electrolyte concentrations, pH, and volume, together with a modification of sympathovagal balance. All these changes affect cardiac electrophysiology, possibly leading to an increased arrhythmic risk. Computational modeling may help to investigate the impact of HDrelated changes on atrial electrophysiology. However, many different human atrial action potential (AP) models are currently available, all validated only with the standard electrolyte concentrations used in experiments. Therefore, they may respond in different ways to the same environmental changes. After an overview on how the computational approach has been used in the past to investigate the effect of HD therapy on cardiac electrophysiology, the aim of this work has been to assess the current state of the art in human atrial AP models, with respect to the HD context. All the published human atrial AP models have been considered and tested for electrolytes, volume changes, and different acetylcholine concentrations. Most of them proved to be reliable for single modifications, but all of them showed some drawbacks. Therefore, there is room for a new human atrial AP model, hopefully able to physiologically reproduce all the HDrelated effects. At the moment, work is still in progress in this specific field.Computational and Mathematical Methods in Medicine 12/2014; · 1.02 Impact Factor  [Show abstract] [Hide abstract]
ABSTRACT: Chaste is an opensource C++ library for computational biology that has welldeveloped cardiac electrophysiology tissue simulation support. In this paper, we introduce the features available for performing cardiac electrophysiology action potential simulations using a wide range of models from the Physiome repository. The mathematics of the models are described in CellML, with units for all quantities. The primary idea is that the model is defined in one place (the CellML file), and all model code is autogenerated at compile or run time; it never has to be manually edited. We use ontological annotation to identify model variables describing certain biological quantities (membrane voltage, capacitance, etc.) to allow us to import any relevant CellML models into the Chaste framework in consistent units and to interact with them via consistent interfaces. This approach provides a great deal of flexibility for analysing different models of the same system. Chaste provides a wide choice of numerical methods for solving the ordinary differential equations that describe the models. Fixedtimestep explicit and implicit solvers are provided, as discussed in previous work. Here we introduce the Rush–Larsen and Generalized Rush–Larsen integration techniques, made available via symbolic manipulation of the model equations, which are automatically rearranged into the forms required by these approaches. We have also integrated the CVODE solvers, a ‘gold standard’ for stiff systems, and we have developed support for symbolic computation of the Jacobian matrix, yielding further increases in the performance and accuracy of CVODE. We discuss some of the technical details of this work and compare the performance of the available numerical methods. Finally, we discuss how this is generalized in our functional curation framework, which uses a domainspecific language for defining complex experiments as a basis for comparison of model behavior.Frontiers in Physiology 01/2015; 5:511.
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