What is heart failure?

Abstract This chapter provides an overview of heart failure. The term ‘heart failure’ is usually used freely between clinicians to describe what is wrong with individual patients, yet despite the fact that heart failure is so very common, it is very difficult to define it satisfactorily. Some difficulties arise because of the effects of modern treatment: while it might be reasonable to define acute heart failure in terms of some haemodynamic variable, the situation becomes very different in chronic treated heart failure. Ultimately, heart failure is a clinical syndrome characterized by a constellation of symptoms and signs, and not a discrete diagnosis. The chapter then highlights the importance of natriuretic peptide testing in diagnosing heart failure. It also looks at how the clinical pattern of heart failure can be viewed as a consequence of mammalian evolution, and considers some older descriptions of heart failure. Finally, the chapter details the clinical course of heart failure and identifies three models—the haemodynamic model, neurohormonal model, and peripheral model—which are helpful in thinking about the pathophysiology of heart failure and in suggesting avenues for therapeutic development.