The heart is a beating muscle that pumps blood to the body through the circulatory system. Each heartbeat is stimulated by electrical signals that travel through special nerve pathways in the heart muscle. These signals can be measured by an electrocardiogram, or EKG.

The heart's signals begin at a spot called the sino-atrial node, or SA node, which is located in the top right chamber, or atrium. The signal then branches out through both the right and left atria, causing them to contract and push blood into the lower chambers, or ventricles.

The electrical signal continues into the ventricles via the atrioventricular node, or AV node, and then into a nerve pathway called the bundle of His. The bundle of His is located in the tissue that separates the ventricles. The signal passes down the bundle and into the left and right bundle branches, located within the ventricles. This causes the ventricles to contract and pump blood to the lungs and body, creating a heartbeat.

As the heart's natural pacemaker, the conduction system keeps the heart beating at a normal rate of 60 to 100 beats per minute. If the pacemaker is disrupted, the heart may beat at an abnormal rate, impacting the circulation of blood throughout the body