Aims: 

Cardiovascular dysregulation and autonomic neuropathy are common complications of diabetes mellitus (DM). Modern sensitive methods, including heart rate variability (HRV) analysis, can detect autonomic nervous system dysregulation even in early phases of DM. Methods of nonlinear dynamics are increasingly applied to HRV analysis to improve the description and classification of cardiac dysregulation during different pathological conditions. In contrast to other nonlinear methods, investigation of symbolic patterns after coarse graining of the dynamics – symbolic dynamics analysis – can be applied also to relatively short (few hundreds of heart beats) recordings. The aim of this study was to ascertain which of the HRV symbolic dynamics measures are different in young patients with DM compared to control group.

Methods: 

We investigated patients with type 1 DM (17, 10 females, 7 males) aged 12.9-31.5 years (mean+/­SEM: 22.4+/-1.0 years) and 17 age and gender matched subjects. The length of R-R intervals was measured using telemetric system. Several parameters based on 4 symbols encoding were used for quantification of heart rate variability and complexity.

Results: 

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".

Conclusion: 

We conclude that parameters of symbolic dynamics could be used for quantification of information hidden in heart rate time series in patients with dysregulation.