A pacemaker is a small medical device that is implanted into the chest or abdomen in order to regulate abnormal heart rhythms. Its invention is credited to Dr. John Hopps, who in 1950 created the first pacemaker in collaboration with Dr. W.G. Bigelow and Dr. J.C. Calahan, at the Banting Institute in Toronto. Pacemakers can be either temporary or permanent, but in both cases they are made up of two key components.
Pulse Generator
The pulse generator is the hub of the pacemaker and consists of a sealed lithium battery and a small electronic circuit. The pulse generator is responsible for producing the electrical signals that cause the heart to beat. According to the Cincinnati Children's Heart Institute, the pulse generator is very small and weighs between 20 and 30 g. The lifespan of the pulse generator is finite and will likely need to replaced every four to 10 years. The patient's cardiologist will be able to determine when the pulse generator needs to be replaced well before the batteries run out.
Leads
The leads are insulated, flexible wires that carry the electrical signals from the pulse generator to the heart. A pacemaker may have one or two leads. A pacemaker with one lead is called a single-chamber pacemaker; a pacemaker with two leads in known as dual-chamber pacemaker. The lead in a single-chamber pacemaker is attached to either the atrium or the ventricle. The leads in a dual-chamber pacemaker are attached to the atrium and the ventricle. A physician will decide which type of pacemaker is needed, based on the nature of rhythm disruption in the patient.
Other Components
Pacemakers contain other components that allow the pulse generator to communicate with the leads, including the electrode and the fixation mechanism. The electrode is located at the tip of lead and is responsible for delivering electricity to the heart. It can also take information from the heart and deliver it back to the generator. The fixation mechanism allows the tip of the lead to be fixed to the heart chambers; it is usually made of a metal alloy.
