ATP plays a central role in the two leading causes of cardiac morbidity and mortality in the western world: ischemia and heart failure. We are in our infancy applying what is known about biology and chemistry of ATP toward developing effective therapies for these diseases. In this volume, the current understanding of the chemistry and biology of ATP specifically in the cardiomyocyte is presented. New insights into ATP have been gleaned using biophysical techniques allowing dynamic measurement of chemical events in the intact beating heart and using new animal models in which cardiac proteins are either over expressed, deleted or harbor specific mutations. This book provides a summary of the basic understanding and includes illustrations of why ATP and the Heart is important to both the clinician and scientist.