The part of the cardiac conduction system known as the “pacemaker of the heart” is the Sinoatrial Node (SA Node). The SA node is a small, specialized group of cells located in the upper part of the right atrium, near the entrance of the superior vena cava. It generates electrical impulses spontaneously and at a regular interval, typically around 60 to 100 times per minute in a healthy adult at rest.

The SA node is often referred to as the natural pacemaker of the heart because it initiates the electrical signals that set the rhythm for the entire heart. These electrical impulses spread rapidly through the atria, causing them to contract and push blood into the ventricles. The SA node’s ability to generate electrical activity is due to its unique properties, including automaticity and a higher intrinsic rate of depolarization compared to other cardiac cells.

Although the SA node is the primary pacemaker of the heart, other parts of the cardiac conduction system, such as the atrioventricular node (AV node) and the Purkinje fibers, can also generate electrical impulses under certain circumstances. However, the SA node maintains its role as the dominant pacemaker due to its intrinsic automaticity and its rapid initiation of electrical signals that orchestrate the coordinated contractions of the heart’s chambers.