Cardiac alternans reduction by chaotic attractors in T ± ϵ feedback control

To achieve control in dynamical systems, one usually avoids the generation of chaos. However, an effective control of an unstable dynamical system can also be practically achieved by deliberately inducing chaos in the system if the induced chaotic attractors are confined in a very small region in phase space. Using nonlinear dynamic analysis of the cardiac restitution model, we reveal that the mechanism of the recently proposed T ± ϵ control for cardiac alternans suppression is due to the confined chaotic attractors so generated. These results are confirmed experimentally by detailed phase-space portrait and transition dynamics measurements in whole heart experiments.