On October 31, 1957 – Halloween! – a rolling blackout across parts of Minnesota and western Wisconsin left Minneapolis’ University of Minnesota Hospital without power for three hours. The hospital never anticipated such a dire emergency; two separate power plants provided electricity for the facility and it seemed unlikely that both sources could fail at the same time. One of the most tragic consequences of the hospital’s power loss was the death of a young post-heart surgery patient, whose life was being sustained by an externally-powered heart pacemaker.
When the blackout hit, all the children in the cardiac recovery unit – whose large, cart-borne pacemakers were plugged into wall sockets – were immediately at great risk. The children in the unit were temporarily dependent on pacemakers as part of University of Minnesota heart surgeon Dr. C. Walter Lillehei’s new life-saving efforts to surgically treat children affected by blue baby syndrome. While police officers parked their cruisers outside hospital windows, aiming their headlights inward to provide light, doctors scrambled to administer medication that would hopefully substitute for the inoperative pacemakers. Their efforts were successful for all but one of the fragile patients. The trauma of the baby’s death spurred Dr. Lillehei to consult with Earl Bakken, electrical engineer and founder of Medtronic, the then-fledgling medical device development company. Lillehei asked Bakken, who was still running Medtronic out of his garage, if he could design a portable pacemaker that ran on a battery. Bakken went to work.
His first design, based on a six volt automobile battery, produced more power than needed. Then, Bakken remembered a recent article in Popular Electronics about a new metronome circuit and had a brain flash – “a metronome has the same rates as heart rates,” he realized. The metronome circuit also had a size advantage – it could fit in a box about the size of a paperback book, and sit in bed beside the patient.
Bakken created a prototype and tested in on a dog in the hospital’s laboratory. It worked. Bakken headed back to the garage to make another unit for human patients. When he returned to the hospital the next day, his first unit was already in use in the surgery recovery room. “There was a child in there with this pacemaker connected to him . . . What a great feeling that is to see here’s something we made with our own hands keeping this child alive, ” he said. Concerned that the initial prototype wasn’t really ready for the critical job of supporting human life, he asked Dr. Lillehei why he hadn’t waited for Bakken’s more carefully constructed second unit. According to Bakken, Lillehei replied, “Well as long as this battery-operated pacemaker was available he wasn’t going to risk losing another child to a power failure.”
Bakken was modest about his new invention, claiming that the rapid advances in heart surgery in the 1950’s would inevitably have led to the portable pacemaker’s development. He acknowledged that the Halloween blackout had highlighted the urgency of creating such a device. Out of tragedy, and thanks to Dr. Lillehei and Earl Bakken, heart surgery patients young and old now stood a better chance of surviving to lead long, productive, and healthy lives.