Physiology of the normal and failing heart

Abstract

The muscularized pump that is the adult human heart distributes more than 1900 gallons of blood daily to every organ in the body. The coordinated activity of its chambers, vessels, and valves enables immediate response to constant physiological demands and maintenance of homeostasis. This chapter outlines the physiological response of the normal adult human heart and highlights the adaptations of the failing heart in an attempt to preserve cardiac output. It reviews the anatomy of the heart in detail, including the components of blood supply; innervation and the impact of decreased cardiac output in heart failure patients; the role of cardiomyocytes, endothelial cells, smooth muscle, fibroblasts, and extracellular matrix; the role and importance of myoglobin in oxygen transport and generation of ATP; the physiology behind and regulation of contraction and relaxation; and other key factors. Knowing the structure and functioning of both a healthy and a failing human heart is fundamental to understanding how an injury or infarct impacts the heart's operation and how to best develop a treatment plan. When treating patients with heart failure, this knowledge enables prompt implementation of conventional and emerging therapies that promote reverse remodeling.