heart-lung machine

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun An apparatus through which blood is diverted in order to oxygenate it and pump it throughout the body, used especially during heart surgery to maintain circulation until normal heart and lung function are restored.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun a pump to maintain circulation during heart surgery; diverts blood from the heart and oxygenates it and then pumps it through the body