The Lemelson Center for the Study of Invention & Innovation
Lemelson Center for the Study of Invention and Innovation, Smithsonian Beanie Illustration
Centerpieces   Places of Invention
An exhibition under development

Places of Invention tells the stories of historic and modern communities where people, resources, and spaces have come together to spark inventiveness.

Invention hot spot:
The rise of "Medical Alley" in Minnesota in the 1950s–1970s

Map of Medical Alley region, Minnesota

Minnesota’s Twin Cities region. Courtesy of Wikimedia Commons.

Earl Bakken, 2007

Earl Bakken, inventor of the first wearable, battery-powered, transistorized pacemaker in 1957. Photo by Bobak Ha'Eri and Paul Schmokel, 7 September 2007, courtesy of Wikimedia Commons.

Patent for pivoting disc heart valve invented by Robert Kaster

Pivoting disc heart valve, U.S. Patent, 3,476,143 (1969), invented by Robert Kaster and developed by Lillehei. Courtesy U.S. Patent and Trademark Office.

Patent for the Richard A. De Wall and Clarence Walton Lillehei oxygenator

U.S. Patent 2,854,002 (1958) for the Richard A. DeWall and Clarence Walton Lillehei "oxygenator.". This invention helped to oxygenate a patient’s blood during cardiac surgery. Courtesy U.S. Patent and Trademark Office.

With hundreds of healthcare organizations and medical device companies in the Twin Cities region, Minnesota is home to a medical-technology hot spot with a long history of experimentation, problem-solving, and influential leadership. The 1950s and '60s in particular saw a flurry of radical innovation that established Minnesota's medical-device industry as a world leader.

Many place and personality factors fomented the Minneapolis hot spot: pioneering, skilled medical professionals; research, mentorship, and experimentation in response to patient needs; a spirit of risk-taking undeterred by setbacks; university and clinical settings for testing and implementing new devices and procedures; support for academic-industrial technology transfer; local suppliers of medical-device materials and parts; engineers to staff medical-device companies; and visionary investors, among others.

As an invention hot spot within a hot spot, the University of Minnesota (UMN) played a critical role in supporting innovative research and experimentation, especially in the prolific 1950s and '60s, when research began playing a more prominent role in American hospitals and medical programs that it had before World War II. From 1930 to 1967, UMN's Department of Surgery was chaired by Dr. Owen Wangensteen, a revered inventor and mentor who famously nurtured research-based experimentation and creative thinking among the doctors at UMN. Under Wangensteen's leadership, Minnesota's surgical program became an Edisonian "invention factory."

One of those UMN doctors, and a dedicated educator, C. Walton Lillehei, worked with a long line of surgical residents and engineers to revolutionize life-changing medical procedures and devices. Lillehei and his colleagues showed the world that open-heart surgery was possible and relatively safe-in an era before widespread intensive care units and respirators, when electronic devices were just entering laboratories and operating rooms. In 1952, Lillehei and a team of three other surgeons, performed the first successful, open-heart surgery using hypothermia to slow the heartbeat, reducing the five-year-old patient's need for oxygen during a procedure to repair a hole in her heart.

Lillehei tested a variety of solutions to the problem of blood oxygenation during open-heart surgery. In 1954, with Wangensteen's support, Lillehei performed the first, and highly risky, open-heart operation using cross-circulation, a technique that enabled more sophisticated repairs to the heart. The technique, intended especially for young children unable to handle hypothermia treatment, involved stopping the patient's heart during surgery and linking the patient's circulation system to that of a donor, such as a parent. Lillehei went on to experiment with the bubble oxygenator, predecessor to a heart-lung machine. Lillehei and Richard De Wall, then a recent UMN Medical School graduate, developed, tested, and refined a simple, cheap, efficient, sterilizable blood oxygenator. The Minnesota-based company, Mayon Plastics, founded by UMN chemical-engineering graduate Ray Johnson, remains a thriving medical supplier thanks to its meeting the demand for De Wall-Lillehei blood oxygenator materials in the 1950s.

In 1957, another Lillehei resident improved De Wall's design, inventing a bubble oxygenator that proved key the widespread practice of open-heart surgery. Throughout the 1960s, in collaboration with a series of surgical residents and engineers, Lillehei pioneered several prosthetic heart valves: the Lillehei-Nakib toroidal disc in 1966, the Lillehei-Kaster pivoting disc in 1967, and the Kalke-Lillehei rigid bileaflet prosthesis in 1968.

With their charismatic, determined leadership and support for self-guided as well as collaborative research, Wangensteen and Lillehei helped fuel Minnesota's medical hot spot, but they (and UMN) were not alone in their influence. To put their innovative ideas into practice, medical professionals relied on commercial visionaries, including Manuel Villafana, who resurrected the Kalke-Lillehei heart valve after it failed to find a commercial manufacturer in the late 1960s. In the 1970s, Villafana formed St. Jude Medical Inc. and worked with Lillehei and others to improve, patent, and commercialize heart valves. Whereas Minnesota's world-famous surgical program essentially drove and marketed its own radical innovations in the late 1950s and '60s, medical device manufacturers and start-ups became significant drivers of technological innovation in the 1970s.

Minnesota's medical innovators also relied on chemical, mechanical, and electrical engineers like Earl Bakken, who trained in transistor technology at the UMN Institute of Technology. In 1949, Bakken and his brother-in-law Palmer Hermundslie started a modest business repairing electronic hospital equipment in a Minneapolis garage. Bakken and Dr. Lillehei met serendipitously at the University of Minnesota Hospital. They teamed up to improve the large, unreliable pacemakers then in use, and over four weeks in 1957, Bakken developed the first external, wearable, battery-powered pacemaker. It was used in the hospital on a patient the day after Bakken delivered it. Bakken's business, Medtronic, went on to become a multi-billion-dollar company with dozens of spin-offs started by former Medtronic employees. Medtronic's expansion benefitted from Lillehei's referrals, in addition to Bakken's own vision, problem-solving skills, and "high-tech, high-touch" approach of cutting-edge engineering combined with a concern for human wellness.

The Bakken-Lillehei story, and the University of Minnesota Hospital's culture of innovation in the 1950s and '60s, exemplify the collaboration, risk-taking, and academic-industrial technology transfer at the roots of Minnesota's medical hot spot.

-- Amanda Murray


Sources: Lorna Benson, “Pioneering Heart Patient Returns to the U of M to Say Thanks,” Minnesota Public Radio News (August 31, 2007), accessed February 1, 2011.

Earl Bakken, The Founder of Modern Medical Technology,”Twin Cities Business (July 1999), accessed October 13, 2010.

Rachel Hillman and Jennifer Ridgeway, “Medical Devices Manufacturing: Prescription for Success.”Minnesota Economic Trends Magazine (October 2008).

Kirk Jeffrey, Machines in Our Hearts: The Cardiac Pacemaker, the Implantable Defibrillator, and American Health Care (Baltimore: The Johns Hopkins University Press, 2001).

Minnesota Historical Society Oral History Collection, “Pioneers of the Medical Device Industry in Minnesota, 1995-2001.” Minnesota Historical Society.

Michael P. Moore, “The Genesis of Minnesota’s Medical Alley,”University of Minnesota Medical Bulletin (Winter 1992), accessed October 25, 2010.

David Rhees and Kirk Jeffrey, "Earl Bakken´s Little White Box: The Complex Meanings of the First Transistorized Pacing and Pacemaker,” in Exposing Electronics, edited by Bernard Finn (London: Harwood, 2000).

Elisabeth Roman, “Manuel A. Villafana: From Life at the Bottom to a Remarkable Career in Cardiovascular Medicine,”Puerto Rico Herald (July 7, 2005), accessed October 25, 2010.

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