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ABSTRACT: To realize precise simulation of the left ventricular motion, it is important to utilize an accurate myocardial tissue model which can reproduce various characteristics of myocardial tissue contraction. In this study, we show that the nonlinear characteristics of the passive myocardial tissue property is the essential nature of the nonlinear force-velocity relation and present a formulation for hyperelastic physiological tissue property. Experimental results of our myocardial tissue simulation with the hyperelastic material property proposed are in good agreement with the reported force-velocity relation of real tissue
Engineering in Medicine and Biology Society, 2006. EMBS '06. 28th Annual International Conference of the IEEE; 10/2006
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ABSTRACT: We evaluated the stress distribution in a geometrical shape model and a shape model obtained from human heart using two different fiber orientations. For both orientation models, the results showed large differences of the stress distributions between the mathematical shape model and the measurement based shape model. These results suggest that stress distribution is highly dependent on the model geometry and the usage of a measurement based shape model is important for the evaluation of the left ventricular (LV) wall stress distribution. This fact may have some influences on the reported homogeneity of stress distribution with anatomical fiber orientation model that uses mathematical shape model
Engineering in Medicine and Biology Society, 2006. EMBS '06. 28th Annual International Conference of the IEEE; 10/2006
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ABSTRACT: The efficiency of heart pump function greatly depends on synchronized contraction of myocardial muscle. In this work, contraction simulation of an excitable ventricular tissue cable was constructed to study the influence of excitation patterns on tissue contraction. The tissue cable is composed of elements which contract when excited by an external stimulus. In each calculation step, contraction force of each element is determined by a ventricular cell model. The mechanical deformation is then solved by finite element method and states of cells are updated accordingly. Several factors such as the starting position of the stimulation signal and the conduction velocity of gap-junctions affect contraction behavior. Simulation results show that the activation time, i.e. the time period the stimulation signal needs to spread over the tissue, is a dominant parameter for determining tissue contraction force. Contraction force of myocardial tissue increases monotonically with a decrease in activation time. This result suggests that minimization of activation time might be important for achieving effective tissue contraction
Engineering in Medicine and Biology Society, 2006. EMBS '06. 28th Annual International Conference of the IEEE; 10/2006
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ABSTRACT: The left ventricular mechanical model and the circulation model are important for the cardiovascular dynamics simulation that consider the characteristics of the ventricular cells and the structure of left ventricle (LV). Due to the fact that the cardiovascular dynamics is the result of nonlinear interactions between these two models, simultaneous consideration of both models using a strong coupling method is necessary for an accurate simulation. In this paper, we propose a simulation algorithm that is capable of calculating cardiovascular dynamics model by strong coupling of the left ventricular mechanical model and the circulation model
Engineering in Medicine and Biology Society, 2005. IEEE-EMBS 2005. 27th Annual International Conference of the; 02/2006
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ABSTRACT: Recent advances in constructing accurate cell models have enabled new research areas for establishing accurate tissue and organ models. One important target of such research is heart. However, although the accurate myocardial cell model is becoming available, many elements such as cell orientation, mechanical tissue properties are still not known. On the other hand, computer simulation is becoming important tool for biological research. In such research, biological model is constructed and evaluated with variety of parameters. However, for the organ models such as heart model, it becomes very complicated and difficult to generate and evaluate variety of heart models with different combinations of element models and their parameters. In this paper, we propose an interface which generates complex left ventricular simulation model. We can generate left ventricular simulation models with 3D shape model, cell orientation model, cell electrophysiological model, coronary artery model and tissue mechanical property and model. Obtained simulation results show the effectiveness of the system.
Engineering in Medicine and Biology Society, 2004. IEMBS '04. 26th Annual International Conference of the IEEE; 10/2004
