Rarely, if ever, does a large specialty arise at a single institution to the extent that cardiac surgery did at the University of Minnesota. The specialty's history began long before the university's Division of Cardiovascular and Thoracic Surgery, or even the national Thoracic Surgery Boards were established. Up to 1950, the only operations done in this area were extra-cardiac procedures, such as ligation of patent ductus arteriosus, repair of coarctation of the aorta, or placement of systemic pulmonary artery (Blalock-Taussig) shunts. At the University of Minnesota, however, several surgeons not only dreamed about operating inside the heart, but set about making it a reality.
The obvious stumbling block to intra-cardiac repairs was the ability to support the patient while the heart and lungs were isolated from the circulation. Drs. Clarence Dennis and Richard Varco developed a cardiopulmonary support device; the first two patients placed on bypass were operated on in 1951. Unfortunately, from the combination of lack of accurate preoperative diagnosis and an easily avoidable technical failure on the part of the bypass machine technician (a surgery resident), neither patient survived, so such operations were put on hold.
The world's first successful open-heart procedure was carried out by Dr. F. John Lewis at the University of Minnesota in 1952. Using the technique of hypothermia and inflow occlusion, he did open repairs of secundum-type atrial septal defects without severe complications in about 20 patients from 1952 to 1953. Without an effective means of supporting the patients' circulation, however, only very simple defects could be repaired.
In Philadelphia, Dr. John Gibbon continued to work on a cardiopulmonary bypass system. In 1953 he was the first to successfully repair an atrial septal defect on support. Unfortunately, he was not able to repeat this feat, leaving mechanical cardiopulmonary bypass still unproved.The apparent difficulties in achieving reliable, safe cardiopulmonary bypass led a team of Minnesota surgeons (including Drs. C. Walton Lillehei, Richard L. Varco, Morley Cohen, and Herbert Warden) to use cross-circulation to provide support. With this technique, a blood-matched donor served as the heart-lung machine for the patient. Cross-circulation proved very effective and enabled a string of firsts in repair of lesions. The first closure of a ventricular septal defect, the first repair of an atrioventricular canal, and the first correction of tetralogy of Fallot were all accomplished in 1954. Although some of these patients died, the difficulties lay in the cardiac repair rather than in the means of support.
The cross-circulation operations proved that complex intra-cardiac repairs could be carried out. Efforts continued to develop a perfusion system. The first clinically reliable bubble oxygenator, developed by Drs. Richard DeWall and C. Walton Lillehei in 1955, provided the next breakthrough in cardiac surgery. Now the field was wide open, and many lesions could be repaired. Not only were a number of intra-cardiac lesions first corrected at the University of Minnesota, but the wherewithal was developed to accomplish this elsewhere.
Other major technological advances began at the University of Minnesota. An occasional consequence of open-heart repairs was, and is, the creation of temporary or permanent heart block. The first clinically usable pacemaker was designed by Earl Bakken while working with the cardiac surgeons at the University of Minnesota. The success of this original pacemaker led Bakken to found Medtronic, the number one pacing corporation in the world today. Subsequently, "Medical Alley" was formed as other companies have spun off locally as new technological advances were made.
Although heart transplantation did not begin at the University of Minnesota, the two pioneers received their cardiac surgery education here at our institution. Dr. Christiaan Barnard accomplished the world's first heart transplant in Capetown, South Africa, while Dr. Norman Shumway, from Stanford University, performed the first heart transplant in the United States and made it a clinically useful procedure.
When cardiac surgery became routine at countless hospitals, major breakthroughs were more difficult to come by. Nevertheless, more advances occurred at the University of Minnesota. Improvements in heart valves were made. The tilting disc valve prosthesis (Lillehei-Kaster) was developed here and proved to be a significant advance over the older poppet-style valves. The first bi-leaflet mechanical valve (St. Jude) was designed by a Minnesota engineer and first evaluated experimentally and clinically at the University of Minnesota.