If a baby needs a heart replacement where does it come from?

From another child: Unfortunately there is no synthetic heart. It comes from a child healthy and died of unexpected causes and healthy other wise - ie. Accidents and brain death . It is a sad situation and some parents will consent for the benefit of other family.

Another baby: Any transplant must approximate the size and physiology of the recipient. Infants cannot receive a heart too large & adults cannot receive a heart too small. When of if a donor heart becomes available it is often due to a sudden traumatic injury ( car crash, etc) where irreversible brain injury has occurred, just as with adults.