There are two components to the complete interpretation of an electrocardiogram (ECG): analysis of the rhythm of the ECG waveforms which are the electrical manifestation of cardiac activity; and analysis of the shape (morphology) of the waveforms in order to diagnose many conditions not related to rhythm. Twelve Lead Electrocardiography: Interpretation and Theory deals solely with this second component, and is aimed at students who already have a familiarity with the analysis of heart rhythms. Twelve Lead Electrocardiography for ACLS Providers describes a set of discrete building blocks of easily understood electrophysiologic principals, and then allows the reader to deduce what the 12 lead electrocardiogram will look like under various circumstances. There is no memorizing patterns. Instead emphasis is on understanding and deduction. Retention is greatly enhanced, and more importantly, the reader becomes a more competent interpreter of 12 lead ECGs. The ultimate objective of the text is to enable both cardiologists and non-cardiologists to utilize the 12 lead ECG in daily clinical practice in a competent manner. Cardiology residents, students, emergency physicians and internists, as well as paramedics, physician assistants, and nurse practitioners who are called upon to make initial clinical judgements particularly regarding the evaluation of patients with chest pain will all benefit from the information contained within these pages.