Cutting into a beating heart to heal it almost seems like a contradiction in terms. But for 1950s cardiac surgeons, open-heart surgery became the obvious next step in their battle against heart disease. In order to do this they would have to find a way not only to continue blood flow throughout the body but also to ensure that blood was oxygenated (mixed with oxygen). Pioneering surgeons tried out several methods for open-heart surgery.

The medical equipment and techniques used in a state-of-the-art operating room in 1954 would seem very out of date today. Nurses used two fingers on the inside of the patient's wrist and a wall clock with a large second hand to monitor pulse, glass thermometers to take temperatures, and blood pressure cuffs and stethoscopes to check blood pressure. Electrocardiogram machines to record heart rate and rhythm were available but seldom used. Other operating...