Quantifying heart rate dynamics using different approaches of symbolic dynamics D. Cysarz, A. Porta, N. Montano, P.V. Leeuwen, J. Kurths and N. Wessel Eur. Phys. J. Special Topics, 222 2 (2013) 487-500 Published online: 25 June 2013 DOI: 10.1140/epjst/e2013-01854-7