Cardiopulmonary perfusion refers to situations in which the function of the heart and lungs is taken over by an arti‹cial device: in popular parlance, this is referred to as the heart-lung machine. The basic idea is to immobilize the heart so that it can be operated upon; this means that the blood has to be diverted away from both the right and left sides of the heart and, since the lungs rely on being perfused by blood in order for gas exchange to take place, this function has to be done externally. This type of operation, pioneered in the early 1960s, is termed open heart surgery, which involves opening up the chest and pleural cavity. When the pleural cavity is opened, the lungs de£ate and hence could not contribute to oxygenation even if circulation through them was maintained. More modern techniques try to use minimally invasive or “keyhole” surgery to reduce trauma. However, this is only effective in certain situations, and the open operations, particularly for heart and combined heart and lung transplants, continue to be the operation of choice.