In 1956, Cleveland Clinic performed a groundbreaking operation that established stopped-heart surgery as a regular practice. A team led by Donald Effler, MD, and Laurence Groves, MD, connected the patient — a 17-month-old boy with a ventricular septal defect — to a heart-lung machine designed by Willem Kolff, MD, PhD. Once the machine was pumping blood and oxygen, a dose of potassium citrate temporarily paralyzed the heart. “With a dry, quiet, clearly visible field in which to work, we believe that a new era of heart surgery has opened,” Dr. Effler said. According to news accounts, the patient was “up and about” soon afterward.