Greek also had an alpha copulativum, a- or ha-, expressing union or likeness, which is the a- expressing "together" in acolyte, acoustic, Adelphi, etc. It is from PIE root *sem- (1) "one; as one, together with."
"periodic contraction of the heart and arteries," 1570s, from Greek systole "a drawing together, contraction," from syn- "together" (see syn-) + stem related to stellein "to bring together, draw in; to put, set, place," from PIE *stel-yo-, suffixed form of root *stel- "to put, stand, put in order," with derivatives referring to a standing object or place.
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Definitions of asystole from WordNet
absence of systole; failure of the ventricles of the heart to contract (usually caused by ventricular fibrillation) with consequent absence of the heart beat leading to oxygen lack and eventually to death;