A cardiac pacemaker sends electrical impulses to control the beating of the heart if its rhythm is too fast, slow or irregular. It is placed just near the collarbone in surgery. The first internal pacemaker was invented by Wilson Greatbatch in 1958. In fact, the invention was an accident. In 1956 Greatbatch was building an oscillator to record heart sounds, but he installed a resistor incorrectly. It pulsed at a steady pace that was similar to the sound that was made by a properly beating heart. Greatbatch realized that this piece of technology was the foundation for a device that could control the heart and make it stay in rhythm. Over the next two years, Greatbatch tweaked his invention with the help of Andrew Gage and William Chardack. He received a patent for it and the internal pacemaker was implanted into the first human in 1960. The issue of battery life was addressed when Wilson Greatbatch invented a corrosion-free lithium battery.