Italian doctors implanted an artificial heart that weighed only 11 grams, making it the smallest ever used. It kept the child alive long enough to receive a human heart:

"In March, the smallest artificial heart in the world was implanted at the Bambino Gesu Hospital in Rome," Antonio Amodeo, a senior hospital official, said in a statement.

"The device, a titanium pump weighing only 11 grams and that can endure a flow of up to 1.5 litres per minute, was used in an emergency case of a 16-month-old infant suffering from dilated myocardiopathy with a serious infection of the ventricular assistance device that had been implanted previously."

Link -via Gizmodo

Photo (unrelated) via Flickr user o5com