Computational and Mathematical Methods in Medicine
Volume 8 (2007), Issue 4, Pages 287-296
Original Article

Heart Rate Variability Complexity in the Aging Process

1Departamento de Química-Física, Faculdade de Química, Universidad de La Habana, Cuba
2Faculdade de Biología, Universidad de La Habana, Cuba
3Center of Cybernetic Apply to Medicine, Cuba
4Faculdade de Farmácia/IBMC, Universidade do Porto, Portugal
5Cátedra de Sistemas Complejos “H. Poincaré”, Universidad de La Habana, Cuba

Received 12 January 2007; Revised 10 February 2007; Accepted 25 October 2007

Copyright © 2007 Hindawi Publishing Corporation. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


In the present work, we propose a discrete model to the characterization of heart rate variability (HRV) complexity in the aging process of healthy subjects. We apply the Shannon entropy on the basis of an alternative way to probability calculation and to define a new index taking into consideration the transition probability that is related to the physiological complexity of the system. Our results suggest that in the aging process the capability response decreases according to the reduction of the physiological complexity. In the oldest group, an alternative mechanism emerges to compensate for this lack of capability; however, this effect does not increase the physiological complexity. Concomitantly, we provide some physiological explanation for our results.