This text book was written to be an introduction to interpretation of electrocardiography, not as a complicated text book. The purpose of this book is to present the often complicated explanation of electrocardiography in a simple and easy to read manner. Nurses, medical students and paramedics will find this book very beneficial. Each rhythm is explained in a simple manner which is accompanied by diagrams and rhythm strips to help simplify the concepts. There are very few books that approach this subject in a simplified way which allows the reader to gain a rapid understanding of the subject. It is certain that this publication will satisfy the need for such a book. This third edition has addressed in more depth the recent changes associated with acute coronary syndrome. The last chapter now includes information on how training affects the heart, the changes that are often associated with the athlete's heart. The reader is encouraged to take an active role in the learning process. Having access to rhythm strips and 12 lead electrocardiographs will help the reader develop the skills more quickly. Keeping a journal of interesting rhythm strips will assist with developing these essential interpretation skills. Exercises have been included at the end of each chapter in this new edition, which encourages the reader to test themselves. The main concept expressed in this book is to encourage the reader to develop 'P wave consciousness' - being always on the lookout to find the presence of a P wave. If the P wave is absent then the reader is encouraged to find the reason for its absence.