The pacemaker is a small metal box weighing 20-50g, which is attached to one or more pacing leads (wires) that run to your heart. The pacemaker contains:
- a battery (which usually lasts 6 to 10 years),
- a pulse generator, and
- a tiny computer circuit that converts energy from the battery into electrical impulses, which flow down the wires and stimulate your heart to contract.
The rate at which these electrical impulses are sent out is called the discharge rate.
Setting the pace
Almost all modern pacemakers work on demand. This means that they can be programmed to adjust the discharge rate in response to your body's needs.
This means:
- if the pacemaker senses that your heart has missed a beat or is beating too slowly, it sends signals at a steady rate, and
- if it senses that your heart is beating normally by itself, it does not send out any signals.
Most pacemakers have a special sensor, which recognises body movement or breathing rate, enabling them to speed up the discharge rate when you are active. Doctors describe this as rate responsive.
Storing information
Most pacemakers can analyse and store information about your natural heart rhythms. When you have follow-up appointments at the pacemaker clinic, the technicians and doctors can retrieve this information and use it to check how well the pacemaker and your heart are working.
