Model-based control of cardiac alternans on a ring

This paper describes a systematic approach to sup-pressing cardiac alternans in Purkinje fibers using lo-calized current injections. We investigate the control-lability and observability of the periodically paced No-ble model for different locations of the recording and control electrodes. In particular, we show that the loss of controllability causes the failure of the control ap-proach introduced by Echebarria and Karma [Chaos 12, 923 (2002)] for longer fiber lengths. Furthermore, we explain how the optimal locations for the record-ing and control electrodes and the timing of the feed-back current can be selected, accounting for both linear and nonlinear effects, effectively doubling the length of fibers that can be controlled. Key words Cardiac dynamics, alternans, feedback contro