[Functional state of the cardiovascular system of cosmonauts at rest in long-term space flight]

Analyzed were data of investigation of a group of cosmonauts who participated in long-term Mir missions (125 to 438 days). The scope of investigations made in resting cosmonauts (279 before and 234 in flight) allowed classification of the cardiovascular system functioning in three types depending on the cardiac index. Correlation between circulation type and genetic factors, age and conditions of investigations (at rest or prior to a functional test) has been established. In flight, most often the cosmonauts pointed to intensification of the chronotropic function of the heart, increase in minute volume, rises in the end-systolic blood pressure (BPes) and systolic pressure in the pulmonary artery, hyperkinetic circulation, particularly before functional testing. However, values of the parameters under study did not leave the borderlines of the physiological and, as a rule, age norms. An in-depth analysis revealed three types of reaction to microgravity. Increase in minute volume due to the stroke volume and heart rate was concurrent with the BPes rise. Diminution of the volumes of hemocirculation and development of eukinetic circulation were not found to significantly alter BPes. There were several cosmonauts who did not display any proved shifts in the parameters.