The pacemaker was invented by Wilson Greatbatch, an American engineer and inventor. Greatbatch accidentally discovered the implantable pacemaker in 1958 while working on a heart rhythm recording device. His invention used a transistor oscillator circuit that produced electrical pulses to stimulate the heart. With the help of surgeon Dr. William Chardack, they successfully implanted the first pacemaker in an animal, leading to the development of implantable cardiac pacemakers that have since saved countless lives. Greatbatch's invention was foundational to modern pacemaker technology and is widely recognized as the key breakthrough in cardiac pacing.

Earlier concepts and experimental devices for heart pacing were developed by others such as John Hopps and Albert Hyman, but Wilson Greatbatch created the first practical implantable pacemaker.