Guidewires used during percutaneous coronary interventions have elevated conductance, and, when in place, are electrically isolated from the body fluids by the guiding catheter. In this paper, we present an overview of two simple techniques exploiting these unique conditions to record local electrical activity in the myocardium and to pace the heart. Both actions can be accomplished with standard catheterization laboratory equipment. The operator may obtain useful, real-time information on distal ischemia and/or vitality and react quickly when an emergency pacing is required. The technical details of these techniques are elucidated and their usefulness as clinical and research tools is discussed, with an emphasis on possible future applications.