The circulating blood brings oxygen and nutrients to all the organs and tissues of the body, including the heart itself. It also picks up waste products from the body's cells. These waste products are removed as they're filtered through the kidneys, liver and lungs. The heart also has an electrical system which includes a permanent pacemaker to regulate the heartbeat rate and specialized wiring to transmit the pacemaker beat to all parts of the heart. This pacemaker creates a miniature electrical impulse, on average 70 times a minute.
Some people have an auxiliary pacemaker located in the ventricle.
Occasionally, this pacemaker can fire too early or prematurely, causing a brief flutter sensation or irregular pulse. If both bundles go bad, impulses from the pacemaker never make it to the heart ventricles, causing a very slow heart rate of less than 40 beats per minute.