Perfusionists are trained to operate heart-lung machines during open-heart surgery. In addition, perfusionists often operate ancillary devices such as the cell saver machine intra-aortic balloon pump. A perfusionist is a highly specialized healthcare professional who operates the heart-lung machine during cardiac surgery and other procedures that require cardiopulmonary bypass. They play a critical role in supporting the physiological and circulatory functions of patients undergoing open-heart surgery or other procedures that involve temporary cessation of the heart's pumping action.