chest lead /lēd/ , 1. an electrocardiographic conductor in which the exploring positive electrode is placed on the chest or precordium. The indifferent electrode is placed on the patient’s back for a chest back (CB) lead, on the front of the chest for a chest front (CF) lead, on the left arm for a chest left (CL) lead, and on the right arm for a chest right (CR) lead. 2. (Informal) the tracing produced by such a lead on an electrocardiograph.
