Nine months of Elliott Livingstone's two-year-old life have been spent on a Berlin Heart, a machine that compensates for a life-threatening weakness in his left ventricle.
Just a baby when it was installed, he now moves about Great Ormond Street Hospital pushing a toy trolley while the device pumps blood around his tiny body.
"He deals with so much and just gets on with things," said mother Candace, 32.
"For him, nine months of his two-year-old life have been on this machine and in this hospital.
"So really now this is all he knows, this is what life is for him."
Elliott's progress while he waits for a heart transplant is being followed by the Evening Standard's Give to GOSH Christmas appeal.
The campaign aims to raise money for the hospital in a range of key funding areas.
Cash to will support the creation of a new specialist unit helping children with heart failure to stay well while they wait for a heart transplant.
For Elliott, the wait is made easier to understand by the naming of his Berlin Heart after Thomas the Tank Engine.
"He knows that that's Tommy and he knows that Tommy helps him to feel better," said Candace.
"And he also knows that he's waiting for a new heart and that one day Tommy will be finished once he gets that chance of a new heart."
