Role of the right and left parts of the heart in mechanisms of body adaptation to the conditions of long term space flight according to longitudinal ballistocardiography

The paper reports the results of the Cardiovector space experiment, performed onboard the International Space Station (ISS) in 2014–2017 with the participation of 12 cosmonauts - members of the long term space flights. Each cosmonaut was examined in the following order: twice before launch; every month during the flight and twice after landing. The following physiological signals were registered: electrocardiogram, ballistocardiogram along three mutually transverse axes and three rotation axes, impedance cardiogram, seismocardiogram and pneumotachogram. The experimental protocol consisted of 5 min of rest, 3 min of fixed breathing with 5 and 10 s cycles, and tests with maximal inspiratory and expiratory breath-holds. The paper shows dynamics of BCG amplitude changes along the body longitudinal axis (Y). The investigation showed that microgravity forms a new hemodynamic pattern characterized by increased, compared to that on Earth, filling of the pulmonary circulation at rest, particularly during the first month during mission, and elevation of the left ventricle activity in this period. This fact, probably, points to a gradual unloading of the pulmonary circulation.