Assessment of ventricular repolarization instability in terms of T-wave alternans induced by head-down bed-rest immobilization

Objective : To assess the effects of different durations of simulated microgravity exposure on
ventricular repolarization (VR) in terms of T-wave alternans (TWA) as well as to test whether an
increase in VR heterogeneity could be detected once normal gravity was restored. Approach : A total
of 63 healthy volunteers were recruited in several head-down bed-rest (HDBR) experiments in the
context of the European Space Agency bed-rest strategy. TWA is evaluated during the night period
using ambulatory ECG recordings, before, during and after long- (60 d), mid- (21 d) and short- (5 d)
duration HDBR by the long-term averaging technique. Main results : 5 –21 d of exposure to simulated
microgravity by means of the HDBR model do not lead to a significant increase of cardiac electrical
instability in healthy myocardial substrates up to the point of eliciting TWA on the surface ECG.
However, TWA indices increased after long-term HDBR exposure, once normal gravity was re-es...

Source: Physiological Measurement - October 29, 2019 Category: Physiology Authors: Alba Mart ín-Yebra, Violeta Monasterio, Federica Landreani, Pablo Laguna, Juan Pablo Martínez and Enrico G Caiani Source Type: research