External electronic pacemaker

Canadian electrical engineer John Hopps first developed the artificial pacemaker in 1950. Known as the "father of biomedical engineering in Canada," While doing research on hypothermia, Hopps discovered that if the heart stopped beating because of excessive cooling, it could be started again through artificial stimulation. The first artificial pacemaker was 30 cm long, used vacuum tubes to create pulses and depended on 60Hz of household current. The technology was not small enough to be put inside humans until 1957.