Michael DeBakey was a US surgeon who pioneered surgical techniques for treatment of circulatory system disorders. In 1966 DeBakey implanted the first mechanical device into a human chest to assist the heart. He had already devised the roller pump (1932), a part of the machinery used in open-heart surgery, and developed a method of grafting frozen blood vessels to replace those that were diseased as a means of correcting aortic aneurysms; later (1956), he replaced the grafts with plastic tubing.