Introduction

The primary function of the heart is to pump blood through the circulatory system in order to deliver oxygen and nutrients to the body, and, conversely, provide a means for removal of metabolic waste. This simplified description of myocardial function is underpinned by a complex relationship between the myocardium and the vasculature. In the setting of cardiac surgery, surgeons are faced with patients who present with deranged cardiac physiology at the outset, and in the course of correcting the presenting pathology, surgeons induce temporary derangements to myocardial function as well. In order to safely care for and manage these critically ill patients, a fundamental understanding of cardiovascular physiology is essential. Herein we will review the basic functional unit of the heart—the cardiomyocyte—detailing the subcellular components that allow for electrical signaling and uniform contraction to allow the heart to serve its function.