The advantages of pacing the heart electrically were well known as far back as the early 1900s. Early pacemakers were large, bulky external devices that used vacuum tubes, relied on external ac power, and were frequently too traumatic for young patients. It wasn't until shortly after Medtronic was founded that significant progress began.

Earl Bakken and his brother-in-law Palmer Hermundslie formed Medtronic in April 1949 as a medical equipment service company. Later, it manufactured some of the equipment. Both men conceived the idea of the cardiac pacemaker while Bakken was working part time at Northwestern Hospital in Minneapolis, Minn. There, Bakken had become acquainted with pioneer open-heart surgeon Dr. C. Walton Lillehei of the University of Minnesota, where Bakken was also studying electrical engineering during the 1950s.

Lillehei was looking for a better pacemaking system. One day when Bakken was visiting the hospital, a storm knocked out power, and a patient hooked up to an external pacemaker died. Bakken was asked if he could build a better and more reliable pacemaker. He had read an article in Popular Electronics on how to build a metronome out of newly available devices known as transistors. He proceeded to build such a circuit in a box the size of a paperback book. This external pacemaker with a 9-V output was tried at the hospital on patients, and the results were successful. This was the genesis of Medtronic's external pacemaker.

Elsewhere, others like Siemens in Europe were working on an implantable pacemaker with rechargeable batteries. But these efforts did not bear fruit, since the battery lifetime was only a few hours.

It wasn't until late 1959, when Dr. William Chardack and Dr. Andrew Gage at the Veterans Administration Hospital in Buffalo, N.Y., working with electrical engineer William Greatbatch, came up with a viable implantable pacemaker using primary cells as a power source. It was known as the Chardack-Greatbatch implantable pacemaker. The National Society of Professional Engineers (NSPE) recognized Greatbach's work, the implantable pacemaker (patent number 3,057,356), in 1983 as "one of two major engineering contributions to society during the past 50 years." Greatbatch, through his company Greatbatch Enterprises, licensed his patent to Medtronic in 1961. The company now produces most of the world's lithium batteries used in many current pacemakers and defibrillators.