As the story goes, it was Halloween, October 31, 1957. An explosion occurred at the Northern State Power company’s “Black Dog” transformer. A fire blazed, and the power that Black Dog was maintaining was shunted to connected transformers throughout the metro area. The transformers overloaded and shut down.  An extensive power outage loomed over the city of Minneapolis and outlying region.

At the University of Minnesota, several young patients recovering from open-heart surgery in their rooms at the Variety Club Heart Hospital were in grave danger.  These patients suffered from a post-operative condition known as heart block.  Surgeons had repaired holes within their hearts, but the sutures they used unintentionally disrupted the stimulus that causes the heart to beat regularly. A machine powered by the electrical current from a wall outlet paced the patients’ hearts at a normal rhythm to sustain their circulation. According to many published reports, one of these children died as a result of the blackout.

The very next day, the patients’ doctor, C. Walton Lillehei, the famed University surgeon who pioneered new methods for open-heart surgery at the University Hospitals in 1954, stopped Earl Bakken in a hallway at the hospital. Bakken, an electrical engineer who frequently repaired equipment in the operating rooms, was also the founder of a medical equipment company known as Medtronic. Lillehei asked Bakken to construct a battery-operated pacemaker in order to protect patients with heart block in the case of a power failure.

After tinkering for “about a month” in his garage in North East Minneapolis, Bakken presented a wearable battery-powered transistorized pacemaker to Lillehei in December.  When a few trials on dogs in the laboratory offered satisfactory results, Lillehei connected the prototype pacemaker to a heart block patient and saved the patient’s life. Today, after several decades and billions of dollars later, Medtronic, Inc. is known as the leading medical device manufacturer in the world.

This is how the story has been told, more or less, in many published accounts for nearly half a century. Recent archival processing activity in University Archives has revealed that this narrative of the Halloween blackout of 1957, and subsequent events and inventions, has a few tricks to it…

The story from primary sources at U Archives

The University Archives is the repository of the C. Walton Lillehei papers, a collection of materials that document Lillehei’s entire professional career as a cardiac surgeon. The Open Heart Project, a six-month effort to identify and make materials in this unprocessed collection accessible to the public for research, has uncovered primary sources that question the often repeated narrative of the invention of the battery-powered pacemaker.

On January 30, 1957, Lillehei and his team became the first surgeons to successfully implant an electrode on the muscle tissue of the heart for the treatment of complete heart block. The myocardial electrode was attached by wire to a Grass Physiological Stimulator – an apparatus that provided a low voltage charge that safely stimulated the weakened heart. The stimulator, or pacemaker, derived power from the hospital’s electrical system, and was placed on a wheeled cart so it could be moved around with the patient. Being “plugged in,” so to speak, became quite cumbersome, as extension cords had to be run throughout the hospital hallways in order to move paced patients from the operating rooms to recovery.

On September 16, 1957, a full month and a half before the Halloween blackout, Lillehei wrote to Owen H. Wangensteen, chief of the Department of Surgery, regarding grant funding to support cardiac research, specifically, a project to develop a pacing apparatus:

“… work on this project is being carried out at a feverish pace by Doctors George Stirling, Vincent Gott, and an electrical engineer, Mr. Robert Bruss.  For example, one development is a new feather weight transistorized pacemaker which weighs only a few ounces and which is activated by a dry cell battery.  The patient can wear this taped or strapped to the skin and together with the wire into his heart gives him complete protection…”

In considering the date and content of the letter to Wangensteen it suggests that he began pursuing the development of a battery-operated pacemaker for heart block patients in the summer of 1957, several months prior to the often cited blackout on October 31, 1957.

Newspaper reports from October 31 and November 1, 1957 confirm that there was a wide-spread blackout on Halloween that year. At about 9:00 a.m., in the height of the morning rush hour, the explosion occurred at Black Dog. Power was restored on the University campus by 11:30 a.m., nearly two and a half hours later.  As confirmed by University Hospital Director Ray Amberg, who was quoted in an article in the Minnesota Daily, the hospitals had auxiliary power systems, and although the outage “caused much inconvenience, of course… we were ready to handle any emergency.” Despite reports of inconveniences, such as downtown office workers unable to use elevators, there were no injuries.  One report even noted that, “Because of the relatively brief period of the power curtailment… there appeared to be no damage to refrigerated meats and foods.”

So what of the detail of the reported death of a patient with heart block?  The official state death certificates recorded by the Minnesota Department of Health that are stored on microfilm in the Minnesota Historical Society library provide a possible answer. There was a death at University Hospitals on October 31, 1957, but the patient was 25 years old, the death was not contributed to heart block or complication resulting from a repair of a hole in the heart, and Lillehei was not the patient’s doctor.  The next certificate found where the death was attributed to cardiac failure after the repair of a congenital heart defect was on November 9, following an operation performed on November 8, more than a week after Halloween.

A power outage on Halloween and the fatality of a child can certainly set the scene for a dramatic narrative. While the blackout may have demonstrated the urgency for which a battery-operated transistorized pacemaker was needed, the primary sources uncovered in Lillehei’s collection reveal that the circumstances of the outage did not incite the idea for the invention of the device.  Regardless of the sequence of events in how the battery-powered pacemaker came to be, there is no mistaking that the device has saved millions of lives worldwide, and is one of the top inventions of the 20^th century.

There is one final trick to this story – this one played on the collection processor.  Lillehei’s correspondence is arranged alphabetically.  There is a folder titled “Medtronic” that is dated 1960-1967.  The folder is filled with orders for pacemakers, correspondence between Lillehei and Bakken on suggested modifications to newer models, etc.  One wonders, where is the correspondence from 1957– when Bakken’s transistorized prototype originated–that could help clarify parts of this story?  A note on the front cover of the Medtronic folder states, “For earlier, see Bakken – Pacemaker.”  The boxes of “B” and “P” correspondence have already been processed, and no folder with such title was found.

With several boxes left to process, it is possible the “Bakken – Pacemaker” folder will surface with hope that the contents within will shed new light on the events following the Halloween blackout of 1957 and the exchanges between Lillehei and Bakken in the development of the Medtronic battery-operated transistorized pacemaker.

Wouldn’t that be a treat?

Note: Rebecca Toov isProject Manager, Open Heart Project, University of Minnesota Archives.