Control of ventricular fibrillation using the spatio-temporal chaos control method of spiral breakup on excitable media

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To construct a whole heart organism, models of single (muscle) cells are examined. Electrical properties of single cells are analyzed in detail using the Hodgkin-Huxley equations which is the most physiologically faithful model. It is shown that single cells easily produce chaotic firings when big differences between the time constants of ionic channels of a cell membrane exist. Based on this results, we have proposed the Coupled-Map-Lattice model of excitable media in which a single cell is denoted by a simple chaos neuron model (mapping). The detailed analysis of this excitable media reveals that our simple model is a very good model which extracts essential features of the excitable media to produce various complicated phenomena such as spatio-temporal chaos of spiral breakups.In constructing a model of large system such as a whole heart, the simulation tools which can easily change the inherent property and the number of elements of the large connected network and the connection topology of the network are necessary. We have proposed such tools in which single elements are expressed by single computer programs and the connection between the elements are realized by the communication protocols (UDP) on computer networks.Essential characteristics of spiral waves on excitable media which does not depend on the specific method of the model construction are revealed by the detailed analysis of the models. Finally we have proposed a control method of the annihilation of spiral waves which applies a weak local signal rather than a strong global signal.