Complementing binary symbolic indices of heart period dynamics by acceleration and deceleration runs

Relevant properties of heart period dynamics can be analyzed by methods derived from symbolic dynamics. However, a lot of information is lost especially if the RR tachogram is transformed to a binary representation. Here, we aim to complement measures of binary symbolic dynamics by properties closely related to the binary representation, i.e. runs of accelerations and decelerations of heart period as basic characteristics underlying heart rate variability. This approach is applied to 1079 RR tachograms from healthy subjects covering the entire adulthood (age range: 18 to 84 years). Each parameter was analyzed per age decade. The average RR interval increased at old age compared to the youngest age group (median RR interval 839 ms vs. 970 ms). SDNN was constant up to 39 years and declined for older subjects (56 ms vs. 36 ms). Binary symbolic indices were derived from acceleration and deceleration of heart period. P1V, i.e. binary patterns of length 3 with one variation, decreased for elderly (>70 years, 53,4%) compared to young ages (<29 years, 66,3%). At the same time P2V, i.e. binary patterns with two variations, increased (14,7% vs. 22,7%). The cumulative accelerations and decelerations were largest for youngest subjects and decreased subsequently and was low in the age group 40 to 49 years (accelerations: -73 ms vs. -37 ms, decelerations. 64 ms vs. 34 ms). The analysis of runs of accelerations and decelerations provides information complementing results from binary symbolic dynamics.