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Heart rate and ventricular repolarization variabilities interactions modification by microgravity simulation during head-down bed rest test

Abstract:

Features extracted from heart rate variability (HRV) have allowed to classify several cardiac disorders. In this work, the linear relationship between HRV and ventricular repolarization variability is studied as a possible feature for stratifying risk of cardiac arrhythmias under weightlessness conditions. Three VR beat-to-beat indexes extracted from ECG signals as QT, QTp (QRS onset to T wave peak) and Tpe (peak to end of T wave) were measured. ARARX modeling was used to estimate the VR variability fraction driven by HRV. Head down bed rest as microgravity Earth-based test increased the linear dependency of VR variability driven by HRV. Furthermore, in a pairwise comparison between PRE and POST conditions showed significant differences (p-values < 0.05) for Tpe variability contents. These results evidence a reduced recovery capacity for the Tpe re-polarization variability to restore its linear dependency values to HR in the first moments at the end of BR. © 2013 IEEE.