The Collaborative International Dictionary of English v.0.48:

cardiography \car`di*og"ra*phy\, n.
   1. Description of the heart.
      [Webster 1913 Suppl.]

   2. (Physiol.) Examination of heart activity using a
      cardiograph.
      [Webster 1913 Suppl.]

WordNet (r) 3.0 (2006):

cardiography
    n 1: diagnostic procedure consisting of recording the activity
         of the heart electronically with a cardiograph (and
         producing a cardiogram) [syn: cardiography,
         electrocardiography]