A pacemaker is a small battery operated electronic device that helps set and regulate the rhythm of the heart to a more regular pattern.
Normal physiology of the heart
The heart has its own pacemaker called the sinoatrial node (SA node) which lies at the top of the organ. It generates a regular electrical impulse that travels across the heart muscles via nerves causing the muscles to contract and relax to form a heart beat. This pumping of the heart maintains blood circulation throughout the body.
Pathology and need for a pacemaker
When the inbuilt pacemaker of the heart does not function adequately by itself, the circulation of blood is severely compromised. Therefore, the artificial pacemaker is implanted to help the heart beat regularly.
The implanted pacemaker provides electric stimulation to different parts of the heart to makes it beat at a regular, controlled rate.
Procedure for placement of a pacemaker
The pacemaker is implanted underneath the chest skin just below the collar bone. It is then connected to the heart with tiny wires. The whole procedure takes around an hour to complete. Sometimes the pacemaker may be needed for a short time (such as after a heart attack) and in these cases, it may be attached to the clothes and not implanted under the skin.
The battery unit is a metal box weighing 20-50g and is attached to wires or leads that connect it to the heart. The battery lasts for 8 to 10 years. In the metal box, is a pulse generator and a computer circuit that converts the energy generated into electrical impulses that then travel via the wires to the heart.
Reviewed by Sally Robertson, BSc