Complexity analysis of heart rate control using symbolic dynamics in young diabetic patients

Abstract

Cardiovascular dysregulation and autonomic neuropathy are common complications of diabetes mellitus (DM). Although autonomic neuropathy is considered as one of the late complications of DM, there are some sensitive methods, that can detect autonomic nervous system dysregulation even in early phases of DM. There is ongoing effort to apply methods based on nonlinear dynamics to improve the description and classification of different cardiac states. The aim of this study was to find out which of the heart rate variability parameters of symbolic dynamics are different in young patients with DM compared to control group. Several parameters based on 4 symbols encoding were used for quantification of heart rate variability and complexity. Our results suggest slightly reduced complexity (expressed by marginally nonsignificantly reduced number of “forbidden words”) even in young diabetic patients pointing out to another aspect of heart rate dysregulation in this group. In addition we have found qualitative difference in distribution of symbolic words expressed by parameter “wpsum02”. Parameters of symbolic dynamics could be used (in combination with traditionally used linear HRV measures) for describe additional information in heart rate time series in patients with dysregulation.