This text is a comprehensive introductory level guide to invasive cardiac EP studies. Its focus is to enable the reader to understand and interpret the recording and stimulation techniques used during an EP study. The primary emphasis is on tachyarrhythmia diagnosis, but the book also includes bradycadias, the principles of catheter ablation and new mapping techniques. The main concepts are explained diagrammatically in 4 colour original diagrams with clinical multichannel intracardiac recordings used to illustrate the concepts discussed. The book provides sufficient practical information to enable the reader to plan an EP study and interpret the intracardiac recordings of most common tachycardias. The work gives a practical guide to cardiac electrophysiology, achieved by combining original electrophysiology tracings and line diagrams with a concise text.