A cardiac pacemaker is a small, battery-powered medical device implanted under the skin to regulate heartbeats by sending electrical signals to the heart, ensuring it maintains a normal, steady rhythm, especially when the heart beats too slowly (bradycardia) or irregularly, alleviating symptoms like fatigue, fainting, and shortness of breath. Composed of a pulse generator and wires (leads) connected to the heart, it monitors the heart's natural activity and intervenes with electrical pulses only when needed, preventing the heart from stopping and improving overall heart function.