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Large-Scale Finite Element Analysis of the Beating Heart
Published in Theo C. Pilkington, Bruce Loftis, Joe F. Thompson, Savio L-Y. Woo, Thomas C. Palmer, Thomas F. Budinger, High-Performance Computing in Biomedical Research, 2020
Andrew McCulloch, Julius Guccione, Lewis Waldman, Jack Rogers
Cardiac cells are electrically excitable and tightly coupled to each other. With a sufficiently strong electrical stimulus, the myocyte, which normally supports a negative transmembrane potential gradient at rest, may be transiently depolarized. The time course of excitation and recovery during this cardiac “action potential” is governed by ionic currents which flow across the membrane through specialized voltage-dependent ion channels specific to various ionic species, especially sodium, potassium, and calcium. Following the rapid onset of the action potential, a subsequent stimulus will fail to elicit another response until the cell has recovered sufficiently; this interval is called the absolute refractory period. During the “relative refractory period,” subsequent action potentials can be evoked, but the threshold stimulus is raised.
Biomedical invasive pressure sensor coatings: calibration and waveform perspectives
Published in Journal of Medical Engineering & Technology, 2020
Q. Qananwah, W. Al-Zyoud, A. Al-Zaben
The pump operates rhythmically, and a controller that generates the required deriving pulse waveform, as shown in Figure 5 was used. This waveform is used to derive the pump via H-bridge, which in turn supplies it with sufficient current. The time duration of the pump operation () represents the systolic pressure and it is repeated every 1 s. is changed for each measurement, starting from 40 ms to 130 ms. The selection of the timing based on the ranges of the QRS complex and to simulate cardiac action potential duration in case of sinus or arrhythmic conditions. The above procedures were applied to construct a system that works in a rhythmic way as the heart suitable to be used in our analyses.
Spatiotemporal modeling and optimization for personalized cardiac simulation
Published in IISE Transactions on Healthcare Systems Engineering, 2021
Without loss of generality, we will investigate the calibration problem in the Aliev-Panfilov cardiac simulation model (Aliev & Panfilov, 1996), which is widely used to simulate the whole-heart excitation and propagation of cardiac electrodynamics: where u denotes the normalized transmembrane potential (i.e., ), v models the recovery behavior, and D is a conductivity tensor. Model parameters k, a, and define the shape of cardiac action potential (i.e., time course of the transmembrane potential u). Specifically, parameter k controls the magnitude of the transmembrane electric current, and a bigger k value introduces a larger electric current in the model; parameter a characterizes excitability (i.e., the ability to be activated by electric impulses) of the cardiac tissue, and the excitability will decrease if the value of a increases; parameter defines the coupling strength between u and v, where ξ0 impacts the refractoriness (i.e., the property of cardiac tissue not to respond on the electrical stimulus) of the simulated action potential, and μ1 and μ2 are used to tune the restitution curve, which impacts the duration of the action potential. We will denote the model parameter as (i.e., ) later in this paper.
Electrocardiogram signal generation using electrical model of cardiac cell: application in cardiac ischemia
Published in Journal of Medical Engineering & Technology, 2019
Alireza Fallahi, Hamidreza Ghanbari Khorram, Alireza Kokabi
Simulating ECG signals based on its generation origin can be useful for understanding the behaviour of the heart and diagnosing the heart diseases. Furthermore, testing the ECG recording device is one of the other applications of the ECG simulator. Hoshimiya et al. [10] proposed an electronic circuit oscillator model for the cardiac cells which models cardiac action potential. Later on, this model has been completed by Maeda et al. [11].