Understanding normal cardiac anatomy and physiology is an important component of performing ACLS. The heart is a hollow muscle comprised of four chambers surrounded by thick walls of tissue (septum). The atria are the two upper chambers and the ventricles are the two lower chambers. The left and right halves of the heart work together to pump blood throughout the body. The right atrium (RA) and the right ventricle (RV) pump deoxygenated blood to the lungs where it becomes oxygenated. This oxygen-rich blood returns to the left atrium (LA) and then enters the left ventricle (LV). The LV is the main pump that delivers the newly oxygenated blood to the rest of the body.
Figure 8a
Blood leaves the heart through a large vessel known as the aorta. Valves between each pair of connected chambers prevent the backflow of blood. The two atria contract simultaneously, as do the ventricles, making the contractions of the heart go from top to bottom. Each beat begins in the RA. The LV is the largest and thickest-walled of the four chambers, as it is responsible for pumping the newly oxygenated blood to the rest of the body.