This study represents the first systematic evaluation of dysrhythmias
before, during, and after spaceflight including extravehicular activit
y (EVA). The data, based on 7 Shuttle crew members. revealed a nonsign
ificant decrease in ventricular and supraventricular ectopy during EVA
, suggesting that the incidence of dysrhythmias is no greater during E
VA than with any other phase of a mission or preflight.