Time Irreversibility of Heart Rate Oscillations During Orthostasis
Introduction: Time irreversibility is a characteristic feature of non-equilibrium, complex systems involving cardiovascular control mediated by autonomic nervous system. Its analysis in heart rate variability (HRV) signal represents a new approach to assess cardiovascular regulatory mechanisms. The purpose of this paper was to assess the changes in various time irreversibility indices during the orthostatic test (a balance of autonomic nervous system shifted towards sympathetic predominance). In addition, we tested the behaviour of the selected irreversibility indices in relation to different lengths of analysed data and their mutual dependence.
Methods: We examined the irreversibility of HRV time series obtained from 28 healthy young subjects recorded during 20 minutes in the supine position followed by 15 minutes in the standing position. We used three different time irreversibility indices - Porta's, Guzik's and Costa's indices (P%, G% and A, respectively). The proposed irreversibility indices were derived from data segments containing 300, 600 and 1000 beat-to-beat intervals.
Results: Two of three time irreversibility indices (P% and A) were sensitive to the shift in sympathovagal balance during the orthostatic challenge even when calculated from the shortest data length. Indices were relatively insensitive to data length - there were no significant differences in relation to data length. Despite the difference in algorithms for the calculation of indices P% and A, these are closely mathematically related and do not provide mutually independent information.
Conclusion: We conclude that heart rate irreversibility indices are sensitive to the changes in autonomic tone after the orthostatic challenge even when derived from the 300 interbeat intervals. Porta's index seems to be more sensitive to autonomic nervous balance shift compared to Guzik's index. Costa's index is closely related to P% and do not provide any additional information compared to other indices.
Task Force of the European Society of Cardiology and the North American Society of Pacing and Electrophysiology. Heart rate variability. Standards of measurement, physiological interpretation, and clinical use. Circulation 1996;93:1043 - 65
Casali KR, Casali AG, Montano N, Irigoyen MC, Macagnan F, Guzetti S, Porta A. Multiple testing strategy for the detection of temporal irreversibility in stationary time series. Phys. Rev. E 2008; 77:066204-1-7
Javorka M, Turianikova Z, Tonhajzerova I, Javorka K, Baumert M. The effect of orthostasis on reccurence quantification analysis of heart rate and blood pressure dynamics. Physiol. Meas. 2009; 30: 29 - 41
Porta A, D'addio G, Bassani T, Maestri R, Pinna GD. Assessment of cardiovascular regulation through irreversibility analysis of heart period variability: a 24 hours Holter study in healthy and chronic heart failure populations. Phil. Trans. R. Soc. A 2009; 367:1359-1375
Porta A, Casali KR, Casali AG, Gnecchi-Ruscone T, Tobaldini E, Montano N, Lange S, Geue D, Cysarz D, Van Leeuwen P. Temporal assymetries of short-term heart period variability are linked to autonomic regulation. Am. J. Physiol. Regul. Integr. Comp. Physiol. 2008; 295: R550-R557
Hou F, Zhuang J, Bian C, Tong T, Chen Y, Yin J, Qiu X, Ning X. Analysis of heartbeat asymmetry based on multi-scale time irreversibility test. Physica A 2010; 389:754-760
Costa M, Goldberger AL, Peng CK. Broken assymetry of the human heartbeat: loss of time irreversibility in aging and disease. Phys Rev Lett 2005; 95: 198102-1 - 4
De La Cruz Torres B, Naranjo Orellana J. Multiscale time irreversibility of heartbeat at rest and during aerobic excercise. Cardiovasc. Eng. 2010; 10:1-4
Guzik P, Piskorski J, Krauze T, Wykretowicz A, Wysocki A. Heart rate asymmetry by Poincaré plots of RR intervals. Biomed Tech 2006; 51: 272 - 275
Costa MD, Peng CK, Goldberger AL. Multiscale analysis of heart rate dynamics: Entropy and time irreversibility measures. Cardiovasc. Eng., 2008, vol.8