Compensatory properties of heart rate asymmetry

Heart rate asymmetry (HRA) is a physiologic phenomenon that reflects a systematic and 1-directional difference between heart rate accelerations and decelerations. In terms of variance-based descriptors, HRA causes the contributions from heart rate decelerations to contribute more to short-term variability than accelerations, and for the long-term variability, the relation is reversed. The hypothesis tested in the present article is that this reversal is caused by a compensatory mechanism whose function is to keep the system in relative balance.

Thirty-minute electrocardiographic recordings from 420 young healthy volunteers were analyzed. The variance-based HRA descriptors were calculated. Cases with both short- and long-term HRAs were considered to show compensation. In the binomial test, we looked for statistically significant departures from independence in the distribution of cases possessing both types of asymmetry.

Short-term asymmetry was observed in 77.6% of subjects (P < .0001), and long-term asymmetry, in 69.3% (P < .0001); both types of HRA coexisted in 66.9% (P < .0001) of the whole group. This result is significantly different (P < .0001) from the independent case (53.78%).

The compensation effect between the short- and long-term asymmetries is present in supine resting electrocardiographic recordings in young healthy people.