Electrocardiography and electrophysiology are (or should be) friends.
D002118:Calcium / Q000502:physiology; D003201:Computers; D004562:Electrocardiography; D004594:Electrophysiology; D006321:Heart / Q000502:physiology; D006801:Humans; D009200:Myocardial Contraction
D002118:Calcium