Dr. Greenfield was an honors graduate of Baylor College of Medicine in 1958 and completed his surgical training at the Johns Hopkins Hospital. He recently retired as Chairman of the Department of Surgery and Surgeon-in-Chief of University of Michigan Hospitals, and is serving currently as Chair Emeritus. Dr. Greenfield is board-certified in General, Vascular and Cardiothoracic Surgery and has been listed in the Best Doctors in America since 1992. Dr. Greenfield is the inventor of the Greenfield vena caval filter for protection against blood clots and holds the Frederick A. Coller Distinguished Chair in Surgery. He is the author of over 300 articles, 100 chapters, and two major textbooks. His interests include vascular surgery, venous disease, and surgery for thoracic outlet syndrome.