http://www.cnn.com/2008/HEALTH/07/12....ap/index.html
At age 23, while still in medical school at Tulane University, DeBakey invented the roller pump, the significance of which was not realized for another 20 years, when it became an essential component of the heart-lung machine.[5] The pump provided a continuous flow of blood during operating procedures, this in turn made open-heart surgery possible.
With his mentor, Alton Ochsner, he postulated, in 1939, a strong link between smoking and carcinoma of the lung. DeBakey was one of the first to perform coronary artery bypass surgery, and in 1953 he performed the first successful carotid endarterectomy. A pioneer in the development of an artificial heart, DeBakey was the first to use a external heart pump successfully in a patient - a left ventricular bypass pump.
His patients ranged from penniless peasants from the Third World to such famous figures as the Duke of Windsor, the Shah of Iran, King Hussein of Jordan, Turkish President Turgut Ozal, Nicaraguan Leader Violetta Chamorro and Presidents Kennedy, Johnson and Nixon.