This paper discusses the effectiveness of symbolic dynamics as a nonlinear approach to analyzing heart rate and blood pressure variability for improved characterization of different cardiovascular regulations and dysregulations.

Heart rate variability (HRV) and blood pressure variability (BPV) reflect the complex interactions of the many different control loops of the cardiovascular system. The detailed description and classification of dynamic changes using time and frequency measures is therefore often insufficient. This paper introduces new methods of non-linear dynamics, especially from symbolic dynamics, to distinguish between different states of autonomic interactions. It demonstrates that parameters obtained from symbolic dynamics are useful for risk stratification after myocardial infarction, for characterization of different cardiovascular diseases, and for phenotyping in genetic studies.