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Cell tensegrity model has been widely accepted as a qualitative and recently quantitative method to describe the cellular mechanics. It is based on the fact the cell body is an inhomogeneous cytoskeleton based structure bounded by a soft membrane. Cell establishes force balance under certain structural arrangement through its focal adhesions and intercellular adhesions, under which the prestress is...
In this work we present a new electromechanical cardiac myocyte model tailored to reproduce the electrical and force generating activities of human ventricular myocytes. The model was created by coupling two existing models: the ten Tusscher electrophysiology model and the Rice myofilament mechanics model. The parameters of the new model were adjusted in order to replicate the available experimental...
Here we describe new computational models of cardiac electromechanics starting from the cellular scale and building to the tissue, organ and system scales. We summarize application to human genetic diseases (LQT1 and LQT3) and to modeling of congestive heart failure.
In this simulation study, we hypothesize that transmural heterogeneity in ion channel properties serves to homogenize cardiac workload. Mechanics and electrophysiology were modeled both on cellular and tissue level. Endo-, midmyo- and epicardial cells differed in ion channel properties only. A preload-afterload experiment was simulated to analyze cardiac pump function during normal conduction from...
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)...
In this paper, we present a simulation study of transmural cellular electromechanical properties in heart failure based on a integrated and refined heart cell model of Luo-Rudy II model and modified Hunter-McCullochter Keurs mechanical model. The results show that prolonged action potential duration (APD) and APD rate-adaptation are more obviously transmurally heterogeneous in heart failure than those...
The mechanisms by which spontaneous electrical activity originates in the ischemic heart and leads to arrhythmia remain unknown, however mechanical stretch of the diseased region has been hypothesized to play a role. The goal of this study is to investigate the conditions that favor the initiation of stretch-induced premature beats in the ischemic heart. We employ a mathematical model of the ischemic...
Atheromatous plaque rupture is the cause of the majority of strokes and heart attacks in the developed world. The role of calcium deposits and their contribution to plaque vulnerability are controversial. Some studies have suggested that calcified plaque tends to be more stable whereas others have suggested the opposite. This study uses a finite element model to evaluate the effect of calcium deposits...
Effects of heart failure on the mechanical function of the heart are difficult to assess experimentally, yet they pose a serious physiological challenge. By integrating modified cellular action potential model based on experimental data of heart failure with modified Hunter-McCulloch-ter Keurs (HMT) mechanical heart cell model, an electromechanical cardiac cell model was constructed and used to study...
Sarcomeres are modeled by parallel and series arrangements of thick (myosin) and thin (actin) filaments whose masses are considered. Contractile force is generated by viscoelastic crossbridge bonds which link the filaments. If bond formation is not perfectly synchronous throughout the sarcomere, small movements of thick with respect to thin filaments result. Such movements lead to bond detachment...
Fatigue of striated muscle after intense exercise of moderate duration can be separated into two distinct types, distinguishable on the basis of their recovery rates. High-frequency fatigue (HF), a decrease in force produced by high-frequency stimulation of a muscle, recovers over the course of minutes to tens of minutes. Low-frequency fatigue (LF), a decrease in twitch tension or force elicited by...
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