In 1958, C. Walton Lillehei and Dr. Richard A. DeWall at the University of Minnesota Heart Hospital co-invent a heart-lung machine, called a helix reservoir bubble oxygenator, which bubbled oxygen through the blood during an operation making open-heart surgery possible.

Used during heart surgery, the inexpensive and simple arrangement of cylinders and tubing re-routs the patient’s blood mixing it with oxygen. At Minnesota, the DeWall oxygenator has completely replaced the cross-circulation method which involved connecting the blood stream of the patient to a human donor whose heart and lungs functioned for both during surgery.