用低通滤波方法终止心脏组织中的螺旋波和时空混沌

通过让心肌细胞钠离子通道的触发门变量延迟打开, 使介质具有激发延迟能力, 介质延迟激发时间随控制电压和刺激频率增加而增加, 当控制电压超过一个阈值时, 延迟激发介质具有低通滤波作用:低频波可以连续通过, 而高频波不能连续通过. 本文用Luo-Rudy相I模型研究了介质延迟激发对螺旋波和时空混沌的影响, 数值模拟结果表明: 当控制电压超过阈值时, 介质的延迟激发可有效消除螺旋波和时空混沌; 从小逐渐增大控制电压, 在钙最大电导率较小情况下, 延迟激发会导致介质激发性降低, 使螺旋波漫游幅度增大, 直至传导障碍导致螺旋波消失; 当钙最大电导率较大时, 延迟激发会导致螺旋波失稳变弱, 这样当控制电压增加到一定值时, 时空混沌可以演化成漫游螺旋波, 当控制参数被适当选取时, 观察到漫游幅度大的螺旋波漫游出系统边界消失现象, 继续增大控制电压将导致时空混沌直接消失.

Terminating the spiral wave and spatiotemporal chaos in cardiac tissue using the low-pass filtering scheme

To cause the sodium ion activation gate of cardiomyocyte delay to open, the ability of excitation delay should be given to the medium. The time of excitation delay of the medium increases as the control voltage and frequency of stimulation increase. When the control voltage exceeds a threshold value, the medium with excitation delay has the property of low-pass filtering: low-frequency waves can continuously pass through the medium, whereas the high-frequency wave does not pass consecutively. In this paper, the effect of excitation delay of the medium on spiral waves and spatiotemporal chaos is investigated by using Luo-Rudy phase I model. Numerical simulation results show that when the control voltage exceeds the threshold value, the excitation delay of the medium can effectively eliminate the spiral wave and spatiotemporal chaos. When the control voltage gradually increases from a small value, at a small maximal conductance of calcium channel, the excitation delay could reduce the excitability of the medium, making the amplitude of the spiral wave meander increase until conduction failure results in the disappearance of the spiral wave. Under a large maximal conductance of calcium channel, the excitation delay can reduce the unstability of the spiral wave so that spatiotemporal chaos evolve into meandering spiral waves when the control voltage is large enough. The phenomenon that the spiral wave with a large meandering motion of its tip moves out of the system is observed when the control voltage is properly chosen. Further increase of the control voltage leads to the disappearance of spatiotemporal chaos.