Source : Webster's Revised Unabridged Dictionary (1913)

Cardiac \Car"di*ac\, a. [L. cardiacus, Gr. ?, fr. ? heart: cf.
   F. cardiaque.]
   1. (Anat.) Pertaining to, resembling, or hear the heart; as,
      the cardiac arteries; the cardiac, or left, end of the
      stomach.

   2. (Med.) Exciting action in the heart, through the medium of
      the stomach; cordial; stimulant.

   {Cardiac passion} (Med.) cardialgia; heartburn. [Archaic]

   {Cardiac wheel}. (Mach.) See {Heart wheel}.

Cardiac \Car"di*ac\ n. (Med.)
   A medicine which excites action in the stomach; a cardial.

Source : WordNet®

cardiac
     adj : of or relating to the heart; "cardiac arrest"