[Cardiac arrhythmias in exposure to +Gz loads after immersion]

The frequency and pattern of cardiac arrhythmias were studied during an exposure to acceleration +3 Gz for 5 min before and after 3- and 13-day dry immersion. Following immersion the frequency of extrasystolic arrhythmias increased four-fold and more severe arrhythmias--group and systemic extrasystoles--developed as compared with control exposures. The following factors--increased in the parasympathetic tone, disorders in the systemic and regional circulation and fluid-electrolyte balance--seemed to be mainly responsible for distrubed regulation of the cardiovasucular rhythm during a post-immersion exposure to acceleration.