Fig. 3. Clarence Dennis with the first heart-lung machine at the University of Minnesota.

called, was a bright (he completed his master's and doctoral degrees during this time also) and impulsive maverick, always pushing to the next level of care for his clinical patients, for whom he had great empathy. Lillehei and his team launched many surgical innovations during this period, primarily because of their hands-on research experiences in the experimental dog laboratories.

Interestingly, prior to 1950, the heart was considered the core of human emotion, with a role in human feelings toward others and even the soul itself. It was not until the medical profession began to view the heart more physiologically, as a pump or machine within the body, that researchers and clinicians began to develop new ways to repair and replace worn-out parts of the heart; innovations in the field of cardiac surgery then flourished (Table 2).

Such innovation became prominent at the University of Minnesota. Soon thereafter, Dr. Clarence Dennis designed the first heart-lung machine for total cardiopulmonary bypass, which was subsequently tested successfully on dogs (Fig. 3). However, when Dennis and his team used the heart-lung machine in the clinical area for the first time on April 5, 1951, the patient died because of complications. A second patient also died during surgery from massive air embolism. Not long after, Dr. Dennis moved his machine and most of his team to New York City (1).

Table 2

University of Minnesota Milestones

1887 New standards requiring medical students to pass exams and gain medical examining board approval (led by Medical

School Dean Perry Millard) 1911 Minnesota became the first state to mandate hospital internships for medical students 1930s Discovery of link between cholesterol and heart disease (Ancel Keys)

1950 First adaptation of the mass spectrograph (Alfred Nier)

1951 First attempt to use a heart-lung machine (Clarence Dennis)

1952 First successful open heart surgery using hypothermia (F. John Lewis)

1953 First jejunoileal bypass (Richard L.Varco)

1954 First open heart procedure using cross-circulation (C. Walton Lillehei)

1954 First surgical correction of tetralogy of Fallot (C. Walton Lillehei)

1955 First successful use of the bubble oxygenator (Richard DeWall)

1958 First use of a small, portable, battery-powered pacemaker (Earl Bakken) 1963 First human partial ileal bypass (Henry Buckwald)

1966 First clinical pancreas transplant (William D. Kelly and Richard C. Lillehei)

1966-1968 First prosthetic heart valves (Lillehei-Nakib toroidal disk, 1966; Lillehei-Kaster pivoting disk, 1967; Kalke-Lillehei rigid bileaflet prosthesis, 1968)

1967 Bretylium, a drug developed by Marvin Bacaner, saved the life of Dwight Eisenhower

1967 World's first heart transplant (Dr. Christiaan Barnard, trained by C. Walton Lillehei)

1968 First successful bone marrow transplant (Robert A. Good)

1969 Invention of implantable drug pump (Henry Buckwald, Richard Varco, Frank Dorman, Perry L. Blackshear, Perry J. Blackshear)

1976 Medical Device Amendment to FDA Cosmetic Act

1977 First implant of St. Jude mechanical heart valve at University Hospital

1988 HDI/Pulse Wave® profiler founded (Hypertension Diagnostics Inc. [St. Paul, MN], Jay Cohn, Stanley Finkelstein).

1993 Angel Wings transcatheter closure device invented (Gladwin Das)

1994 First successful simultaneous pancreas-kidney transplant using a living donor (David Sutherland)

1995 Amplatzer Occlusion Devices founded (AGA Medical Corp., Kurt Amplatz) 1997 First kidney-bowel transplant (Rainer Gruessner)

1999 CardioPump Device evaluated (Keith Lurie et al.)

2000 By 2000, University alumni have founded 1500 technology companies in Minnesota, contributing at least $30 billion to the state's economy

2000 By 2000, University's medical school has produced more family doctors than any other institution in the United States

The next major University of Minnesota (worldwide) milestone in cardiac surgery was the first open heart surgery using hypothermia on September 2, 1952, by Dr. F. John Lewis (Fig. 4). This procedure, suggested by Dr. W.G. Bigelow of Toronto, lowered the body temperature of patients 12-15┬░ to reduce their blood flow, thereby reducing the body's need for oxygen. Brain cells would die after 3-4 min at normal temperature without oxygen, but hypothermia allowed Dr. Lewis and his university research team (Drs. Mansur Taufic, C. Walton Lillehei, and Richard Varco) to successfully complete a 5.5-min repair of the atrial septum on a 5-year-old patient. This was recognized as a landmark in the history of cardiac surgery; until this time, no surgeon had succeeded in opening the heart to perform intracardiac repair under direct vision. Hypothermia with inflow stasis proved to be excellent for some of the simpler surgical repairs, but it was inadequate for more extensive cardiac procedures. "The basic problem was the lack of any means to rewarm a cold, nonbeating heart" (2).

The next milestone, although not accomplished at the University of Minnesota, occurred on May 6, 1953, when Dr. J. Gibbon closed an atrial septal defect using a pump oxygenator for an intracardiac operation. Although this first success with the pump oxygenator was well received, it aroused surprisingly

Fig. 4. In this 1952 photo, Richard L. Varco (left) and F. John Lewis stand behind the hypothermia machine that they used during the world's first successful open heart surgery.
Fig. 5. Diagram of cross-circulation.

little excitement or enthusiasm among cardiologists and cardiac surgeons at that time, likely because other centers had launched their own experiments with bubble oxygenators. Interestingly, Gibbon was never able to repeat his one clinical success; he ultimately became discouraged and did not use the pump oxygenator again.

There was a common scenario, namely, good results with acceptable survival in the experimental animals but nearly universal failure when the same apparatus and techniques were applied to human beings. Thus, many of the most experienced investigators concluded with seemingly impeccable logic that the problems were not with the perfusion techniques or the heart lung machines. Rather, they came to believe that the "sick human heart" ravaged by failure, could not possibly be expected to tolerate the magnitude of the operation required and then recover with good output, as occurred when the same machines and techniques were applied to healthy dogs. Thus, discouragement and pessimism about the future of open heart surgery was widespread. (2)

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