characterized by alternate contraction and dilatation, as the action of the heart
See systaltic in American Heritage Dictionary 4
sys·tal·tic
adjective
Alternately contracting and dilating, as the heart; pulsating.
Origin: Late Latin systalticus, from Greek sustaltikos, from sustellein, to contract : sun-, syn- + stellein, to send; see stel- in Indo-European roots.