Nonlinear dynamic mechanisms of the integer multiple rhythms generated by cardiac myocytes
心肌细胞团搏动整数倍节律的非线性动力学机制

Coupled models of cardiac myocytes were used to investigate the mechanisms of integer multiple rhythms discovered experimentally. Simulation in the deterministic model elucidated a rhythm transition process governed by a period adding bifurcation scenario. Simulation using the stochastic model further revealed that integer multiple rhythms occurred near each of the bifurcation points in the bifurcation scenario. The 0-1 integer multiple rhythm appeared near the Hopf bifurcation point, while the 1-2 integer multiple rhythm appeared near the period adding bifurcation point between two limit cycles. The analysis of the phase space trajectories clearly elucidated that the integer multiple rhythms were formed by a stochastic alternating of the system between two neighbouring orbits. Such theoretical analysis not only revealed the dynamic mechanism of the integer multiple rhythms, but also elucidated the relations of the integer multiple rhythms with other rhythm patterns within the context of a period adding bifurcation scenario. Our experimental and theoretical works created a new way for the study of the principles of the cardiac rhythm transitions.