Doctors in Italy implanted an artificial heart into a 15-year-old boy on Saturday, the first time the procedure has been performed on a child, the hospital said.
Heart surgeons at Rome's Bambino Gesu Children's Hospital carried out the 10-hour breakthrough operation on Thursday, and the hospital said it was "cautious" over the boy's condition.
"A permanent artificial heart in the inside of the chest was implanted for the first time on an (adolescent) patient. So far this type of implant has only taken place on adults," said the hospital in a statement.
The artificial heart is four centimetres (1.6 inches) wide and weighs 400 grammes (14 ounces), and special measures were taken to reduce the risk of infection.
"The risk of infection represents the primary cause of failure of alternative solutions attempted to date worldwide," said the hospital.
The procedure "opened new therapeutic perspectives and hope for life for all patients with cardiac illnesses for whom a transplant is needed, especially for those like Thursday's patient who cannot receive a donated heart for clinical reasons," the statement said.