The "Blackwell"s Basics in Medicine" series deals with fluids and electrolyte balance, each title addressing one particular topic. The first focuses salt and water, with further titles on acid base and potassium. The series goes on to cover organ pathophysiology. Titles on renal and heart failure use the Socratic method. This title is on heart failure. The series follows a standard structure comprising brief questions (progressing from the simple to the more complex) followed by short answers. Case presentations teach the fundamentals of fluid and electrolyte balance, and illustrate various presented topics. The approach is based on pathophysiological knowledge applied to basic medical principles, enabling the reader to interpret clinical data based on sound pathophysiological concepts, and thus provide better patient care.