Arrhythmia essentials / Brian Olshansky, MD, Professor Emeritus of Medicine, University of Iowa Hospitals, Iowa City, Iowa, Cardiac Electrophysicist, Mercy Hospital North Iowa, Mason City, Iowa, Mina K. Chung, MD, Professor of Medicine, Cleveland Clinic, Lerner College of Medicine, Case Western Reserve University, Cardiac Electrophysiology and Pacing, Department of Cardiovascular Medicine, Heart and Vascular Institute, Department of Molecular Cardiology, Lerner Research Institute Cleveland Clinic, Cleveland, Ohio, Steven M. Pogwizd, MD, Featheringill Endowed Professor in Cardiac Arrhythmia Research, Professor of Medicine, Physiology and Biophysics, and Biomedical Engineering, Director, Cardiac Rythm Management Laboratory, University of Alabama at Birmingham, Brimingham, Alabama, Nora Goldschlager, MD, Professor of Clinical Medicine, University of California, San Francisco, Chief, Clinical Cardiology, Director, Coronoary Care Unit, ECG Laboratory and Pacemaker Clinic, San Francisco General Hospital, San Francisco, California.