The heart is a muscular, fist-sized pump with four chambers—two on the left and two on the right. The upper chambers (right and left atria) and lower chambers (right and left ventricles) work together with an electrical system to ensure the heart beats at an appropriate rate. An adult's heart beats 60 to 80 times per minute at rest. The heart's electrical system, starting with a group of cells in the upper part of the heart that acts like a computer (the sinoatrial node), spreads throughout the heart, controlling the heartbeat and causing the muscles to contract and pump blood to the body.

Aging, heart muscle damage from heart attacks, certain medications, and some genetic conditions can cause irregular heart rhythms. If there's a problem with the heart's electrical system (its “computer”), a pacemaker may be necessary. A pacemaker is, simply put, a small battery-powered device. It detects when the heart is beating irregularly or too slowly. It sends a signal to the heart, ensuring it beats at the correct rate. A pacemaker consists of two parts: a generator and leads. The generator contains the information needed to control the heartbeat. The leads are wires that connect the heart to the generator and carry electrical messages to the heart. Pacemaker types vary depending on the individual's condition. Single-chamber, dual-chamber, and biventricular pacemakers are implanted depending on the patient's needs.