Artificial cardiac pacemakers, first developed in the 1950s, produce a regular electrical signal to stimulate the heart. They are used to help patients when the heart's natural rhythm is affected. This is the first British pacemaker which could be completely implanted in the chest cavity. It contains electronic pacing circuitry and mercury-zinc batteries, with fine electrodes carrying the electrical signal to the heart. Nearly 1 million people worldwide now have an implanted pacemaker.

Inv. 1981-1518