The doctors at Rome's Bambino Gesu hospital said the operation was carried out last month and made public this week. The baby, whose identity has not been disclosed, was kept alive for 13 days before the transplant and is now doing well.
The tiny titanium pump weighs only 11 grams and can handle a blood flow of 1.5 liters a minute. An artificial heart for adults weighs 900 grams.
"This is a milestone," surgeon Antonio Amodeo told Reuters television, adding that while the device was now used as bridge leading to a transplant, in the future it could be permanent.