CHANGES IN PRACTICE have made knowledge of the cardiac conduction system and basic electrocardiogram (EKG) interpretation a necessity because perioperative nurses are required to manage an increasing number of patients undergoing i.v. conscious sedation who require EKG monitoring. RAPID EKG INTERPRETATION can reveal arrhythmias before a patient becomes symptomatic. An EKG can reveal underlying cardiac problems and uncover electrolyte imbalances that, if left untreated, could hinder positive patient outcomes. THE CONDUCTION AND CORONARY ARTERY SYSTEMS of the heart are described to enable identification of normal and abnormal EKG rhythms. Each arrhythmia is described, and potential causes and probable treatments are discussed.