Control of bifurcations and chaos in heart rhythms

Cardiac arrhythmias have been closely linked to a variety of bifurcations and chaos. In this paper control of bifurcations and chaos for nonlinear models of cardiac electro-physiologic activity is investigated. Both the Andronov-Hopf bifurcation and period doubling bifurcation are treated. Washout filter aided feedback controllers are employed to control the location and stability of the bifurcations, and the amplitude of the bifurcated solutions. Important features of the dynamic control laws include equilibrium preservation even in the presence of model uncertainty, and automatic targeting of the orbits to be controlled. An independent experiment of suppressing cardiac alternans in a piece of dissected rabbit heart demonstrates the viability and utility of the proposed bifurcation control approach. Controlling nonlinear cardiac dynamics may have important clinical implications as arrhythmias in the heart such as fibrillation and ectopic foci are life threatening. The controller designs described here can lead to the development of future smart clinical pacemakers.