The structure of heart rate asymmetry: deceleration and acceleration runs.

A family of new heart rate asymmetry measures is introduced, namely deceleration and acceleration runs, as well as entropic measures summarizing their distribution. We introduce the theoretical run distribution for shuffled data and use it as a reference for interpreting the results. The measures defined in the paper are applied to actual 24 h Holter ECG recordings from 87 healthy people, and it is demonstrated that the patterns of accelerations are different from those of decelerations. Acceleration runs are longer and more numerous: all runs of accelerations, with the exception of lengths 3 and 4, are more numerous than those of decelerations. These findings are reflected in the difference between the entropic measures for acceleration and deceleration runs: for 74 subjects the acceleration-related entropic parameter is greater than that of decelerations (p < 0.001). For shuffled data there is no difference in the above parameters, and there are more short runs and fewer long runs than in physiological data. The influence of the measuring equipment resolution is also discussed.