Karl William Edmark, MD, was a cardiovascular surgeon and lifelong inventor who was committed to improving outcomes for patients undergoing cardiac surgery. His best-known contribution was to defibrillation science. In the early to mid 1950s, defibrillators used alternating current (AC), which was unreliable and used a high-voltage wave form. Edmark developed a defibrillator that utilized direct current (DC), which provided lower-energy shocks with less trauma to patients and was more reliable and effective in terminating ventricular fibrillation. Edmark's invention, known as the Edmark Pulse Defibrillator, was first used to save the life of a 12-year-old girl in Seattle in 1961.

Edmark founded Physio-Control in 1955. He later hired W. Hunter Simpson to direct the company's growth, while he continued to develop products to benefit patients with cardiac conditions. Edmark's company went on to revolutionize emergency medical care by introducing the first portable defibrillator/monitor that enabled paramedics to provide defibrillation in the field, before transporting the patient to the hospital. This improvement was an important factor in the advent of Seattle's Medic One, a pioneering emergency medical service founded in 1970.