A pacemaker is a device that helps regulate the heartbeat of people who have certain medical conditions. Some synonyms for pacemaker include heart implant, cardiac device, heart regulator and heart rhythm device. Other terms used to refer to this medical device are artificial pacemaker, implantable cardioverter-defibrillator (ICD), and biventricular pacemaker. These devices are generally placed under the skin in the upper chest and connected to the heart with wires. Pacemakers are designed to detect when the heart rate is too slow or irregular and then send low-energy electrical signals to the heart to help restore normal rhythm. They are an essential tool for managing several heart conditions.